GIÁO TRÌNH ANH VĂN CHUYÊN NGHÀNH CÔNG NGHỆ THỰC PHẨM

HoChiMinh University of Industry - Institute of Biotechnology & Food Technology

UNIT 1: WHAT IS FOOD SCIENCE?
Food Science and Technology is a convenient name used to describe the application of scientific
principles to create and maintain a wholesome food supply. Food Science has given us frozen foods,
canned foods, microwave meals, milk which does not need refrigeration, easily prepared traditional foods
and, above all, variety in our diets. The Food Scientist learns and applies a wide range of scientific
knowledge to maintain a high quality, abundant food supply. Food Science allows us to make the best use
of our resources in a sustainable manner and minimize waste.
To be a Food Scientist and help handle the world's food supply to maximum advantage, you need
some familiarity in a number of disciplines including the application of microbiology, chemistry, aspects
of biochemistry and some specialized statistics. The investigation of how biological materials behave in
harvesting, processing, distribution, storage and preparation is complex and full awareness of all
important aspects of the problem requires broad-based training.
With the special training in the applied science known as Food Science, a wide range of
employment opportunities exist for the trained professional. Examples include the Product Development
Specialist, Sensory Scientist, Quality Control and Quality Assurance Specialist, Technical Sales
Specialist, Research and Development Scientist, Marketing, Consumer Behavior and Management to
name a few. Food Science can lead to many exciting and productive careers.
A number of interesting and unique options in the Food Science and Technology program
include:
Food Processing
Product Development
Food Chemistry
Food Microbiology
Food Quality Management
Biochemistry
Marketing and Consumer Behavior
Human Resource Management and Industrial Relations
Asian Studies
Business Management

Why does there seem to be so much chemistry in Food Science? What if I haven't done well in this
subject before?
Food Science requires about the same amount of basic science as other science programs. The
difference is that in Food Science every student gets an exposure to a wide range of scientific disciplines
and has a chance to succeed in more areas. The chemistry you study in the program is not pure chemistry
but applied chemistry e.g. in studying the formation of alcohol during a wine fermentation or the flavor
components of coffee. Food Science classes then allow the student to apply those basic ideas learned in
general science classes.

QUESTIONS
1. What do you know about Food Science and Technology?
2. As a Food Scientist, what specialized subjects do you need apply?
3. After the training course in Food Science, what jobs can you get?
4. List some options in the Food Science and Technology program.
5. Is it right if chemistry that you study in the program is pure chemistry?
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UNIT 3: CARBOHYDRATES
Carbohydrates make up a group of chemical compounds found in plant and animal cells. They
have the empirical formula CnH2nOn, or (CH2O)n. An empirical formula tells the atomic composition of
the compound, but nothing about structure, size, or what chemical bonds are present. Since this formula is
essentially a combination of carbon and water, these materials are called ―hydrates of carbon‖, or
carbohydrates for short.
Carbohydrates are the primary products of plant photosynthesis. The simplified light-driven
reaction of photosynthesis results in the formation of a carbohydrate: nH2O+ nCO2 -(CH2O)n- + nO2.
This type of carbohydrate is found in the structures of plants and is used in the reverse reaction of

photosynthesis (respiration) or is consumed as fuel by plants and animals.
Carbohydrates are widely available and inexpensive, and are used as an energy source for our
bodies and for cell structures. Food carbohydrates include the simple carbohydrates (sugars) and complex
carbohydrates (starches and fiber). Before a big race, distance runners and cyclists eat foods containing
complex carbohydrates (pasta, pizza, rice and bread) to give them sustained energy.
Carbohydrates are divided into monosaccharides, disaccharides, and polysaccharides.
Monosaccharides
Monosaccharides are single-molecule sugars (the prefix ―mono‖ means one) that form the basic
units of carbohydrates. They usually consist of three to seven carbon atoms with attached hydroxyl (OH)
groups in specific stereochemical configurations. The carbons of carbohydrates are traditionally numbered
starting with the carbon of the carbonyl end of the chain (the carbonyl group is the carbon double-bonded
to oxygen).The number of carbons in the molecule generally categorizes monosaccharides. For example,
three-carbon carbohydrate molecules are called trioses, five-carbon molecules are called pentoses, and
six-carbon molecules are called hexoses.
One of the most important monosaccharides is glucose (dextrose). This molecule is the primary
source of chemical energy for living systems. Plants and animals alike use this molecule for energy to
carry out cellular processes. Mammals produce peptide hormones (insulin and glucagon) that regulate
blood glucose levels, and a disease of high blood glucose is called diabetes. Other hexoses include
fructose (found in fruit juices) and galactose.
Different structures are possible for the same monosaccharide. Although glucose and fructose are
identical in chemical composition (C6H12O6), they are very different in structure. Such materials are
called isomers. Isomers in general have very different physical properties based on their structure.
Disaccharides
Disaccharides are two monosaccharide sugar molecules that are chemically joined by a glycosidic
linkage (- O -) to form a ―double sugar‖ (the prefix ―di‖ means two). When two monosaccharide
molecules react to form a glycosidic bond (linkage), a water molecule is generated in the process through
a chemical reaction known as condensation. Therefore, condensation is a reaction where water is removed
and a polymer is formed. The most well known disaccharide found in nature is sucrose, which is also
called cane sugar, beet sugar, or table sugar. Sucrose is a disaccharide of glucose and fructose. Lactose or
milk sugar is a disaccharide of glucose and galactose and is found in milk. Maltose is a disaccharide

composed of two glucose units. Disaccharides can easily be hydrolyzed (the reverse of condensation) to
become monosaccharides, especially in the presence of enzymes (such as the digestive enzymes in our
intestines) or alkaline catalysts. Invert sugar is created from the hydrolysis of sucrose into glucose and
fructose. Bees use enzymes to create invert sugar to make honey. Taffy and other invert sugar type
candies are made from sucrose using heat and alkaline baking soda.
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Disaccharides are classified as oligosaccharides (the prefix ―oligo‖ means few or little). This
group includes carbohydrates with 2 to 20 saccharide units joined together. Carbohydrates containing
more than 20 units are classified as polysaccharides.
Polysaccharides
Polysaccharides (the prefix ―poly‖ means many) are formed when many single sugars are joined
together chemically. Carbohydrates were one of the original molecules that led to the discovery of what
we call polymers. Polysaccharides include starch, glycogen (storage starch in animals), cellulose (found in
the cell walls of plants), and DNA.
Starch is the predominant storage molecule in plants and provides the majority of the food calories
consumed by people worldwide. Most starch granules are composed of a mixture of two polymers: a
linear polysaccharide called amylose and a branched-chain polysaccharide called amylopectin.
Amylopectin chains branch approximately every 20-25 saccharide units. Amylopectin is the more
common form of starch found in plants. Animals store energy in the muscles and liver as glycogen. This
molecule is more highly branched than amylopectin. For longer-term storage, animals convert the food
calories from carbohydrates to fat. In the human and animals, fats are stored in specific parts of the body
called adipose tissue.
Cellulose is the main structural component of plant cell walls and is the most abundant
carbohydrate on earth. Cellulose serves as a source of dietary fiber since, as explained below, humans do
not have the intestinal enzymes necessary to digest it.

Starch and cellulose are both homopolymers (―homo‖ means same) of glucose. The glucose
molecules in the polymer are linked through glycosidic covalent bonds. There are two different
stereochemical configurations of glycosidic bonds—an alpha linkage and a beta linkage. The only
difference between the alpha and beta linkages is the orientation of the linked carbon atoms. Therefore,
glucose polymers can exist in two different structures, with either alpha or beta linkages between the
glucose residues. Starch contains alpha linkages and cellulose contains beta linkages. Because of this
difference, cornstarch has very different physical properties compared to those for cotton and wood.
Salivary amylase only recognizes and catalyzes the breakdown of alpha glycosidic bonds and not beta
bonds. This is why most mammals can digest starch but not cellulose (grasses, plant stems, and leaves).
Food Uses of Carbohydrates
Carbohydrates are widely used in the food industry because of their physical and chemical
properties. The sweet taste of sucrose, glucose, and fructose is used to improve the palatability of many
foods. Lactose is used in the manufacture of cheese food, is a milk solids replacer in the manufacture of
frozen desserts, and is used as a binder in the making of pills/tablets.
Another useful aspect of some carbohydrates is their chemical reducing capability. Sugars with a
free hemiacetal group can readily donate an electron to another molecule. Glucose, fructose, maltose, and
lactose are all reducing sugars. Sucrose or table sugar is not a reducing sugar because its component
monosaccharides are bonded to each other through their hemiacetal group. Reducing sugars react with the
amino acid lysine in a reaction called the Maillard reaction. This common browning reaction produced by
heating the food (baking, roasting, or frying) is necessary for the production of the aromas, colors, and
flavors in caramels, chocolate, coffee, and tea. This non-enzymatic browning reaction differs from the
enzymatic browning that occurs with fresh-cut fruit and vegetables, such as apples and potatoes.
Carbohydrates can protect frozen foods from undesirable textural and structural changes by retarding ice
crystal formation. Polysaccharides can bind water and are used to thicken liquids and to form gels in
sauces, gravies, soups, gelatin desserts, and candies like jelly beans and orange slices. They are also used
to stabilize dispersions, suspensions, and emulsions in foods like ice cream, infant formulas, dairy
desserts, creamy salad dressings, jellies and jams, and candy. Starches are used as binders, adhesives,
moisture retainers, texturizers, and thickeners in foods.
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QUESTIONS:
1. What are monosaccharides?
2. What is the most important monosaccharides? What is its role?
3. Explain the term isomers.
4. What are disaccharides? Give some examples of disaccharides.
5. How is invert sugar created?
6. What are polysaccharides? Give some examples of polysaccharides.
7. What are starch granules composed of?
8. Can human digest starch or cellulose? Why?
9. What are the important roles of carbohydrates in food processing?
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UNIT 4: PROTEINS
Proteins are the most complex and important group of molecules because they possess diverse
functionality to support life. Every cell that makes up plants and animals requires proteins for structure
and function. Enzymes, specialized proteins, catalyze chemical reactions that are necessary for
metabolism and cell reproduction. Our muscles are made from a variety of proteins, and these proteins
allow our muscles to contract, facilitating movement. Other types of proteins in our body are the peptide
hormones; insulin and glucagon are two common examples.
Proteins are complex polymers composed of amino acids. Amino acids contain carbon, hydrogen,
nitrogen, and sometimes sulfur and serve as the monomers for making peptides and proteins. Amino acids
have a basic structure that includes an amino group (NH2) and a carboxyl group (COOH) attached to a
carbon atom. This carbon atom also has a side chain (an ―R‖ group). This side chain can be as simple as
an -H or a -CH3, or even a benzene group.
There are twenty amino acids found in the body. Eight of these amino acids are essential for adults
and children, and nine are essential for infants. Essential means that we cannot synthesize them in

adequate quantities for growth and repair of our bodies, and therefore, must be included in the diet.
Amino acids are linked together by a peptide bond in which the carboxyl carbon of one amino acid
forms a covalent bond with the amino nitrogen of the other amino acid. Short chains of amino acids are
called peptides. Longer chains of amino acids are called polypeptides. Although the term polypeptides
should include proteins, chains with less than 100 amino acid residues are considered to be polypeptides,
while those with 100 or more amino acid residues are considered to be proteins.
Many of the major hormones in the body are peptides. These hormones can influence enzyme
action, metabolism, and physiology. Certain antibiotics and a few anti-tumor agents are also peptides. The
artificial sweetener aspartame is a dipeptide composed of aspartic acid and phenylalanine with a methyl
group attached at the carboxyl terminal group (L-aspartyl-L-phenylalanine methyl ester).
The sequence of amino acid residues in a polypeptide chain is critical for biological function. A
single structural change resulted in a dramatic alteration in physiological function. The ability of an
enzyme to catalyze a particular reaction depends on its specific shape. It’s a lot like a key and lock; if the
key is broken or in a different shape, it won’t open the lock. The receptor sites on cell surfaces must be in
a specific shape for polypeptide hormones to interact with the cell. With twenty different amino acids and
each polypeptide consisting of hundreds of amino acids, it is no wonder that proteins play such a variety
of roles in the human body.
Chemistry of Proteins
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The protein backbone is formed from the peptide bonds created from the amino and carboxyl
groups of each monomer that repeat the pattern -N-C-C- or C-C-N-. The number and sequence of amino
acids in a polypeptide chain is referred to as the primary structure of a protein. The free amino group and
carboxyl group on opposite ends of a polypeptide chain allow proteins to act as pH buffers (resist changes
in pH) inside the cell. The amino group (NH2) accepts a proton and becomes (NH3+ ), and the carboxyl
group (COOH) donates a proton and becomes dissociated (COO-).

As noted previously, each amino acid residue in the polymer may have a different side chain or
chemical group attached to it, such as hydroxyl (OH), amino (NH2), aromatic ring (conjugate rings such
as the phenol ring in phenylalanine), sulfhydryl (SH), carboxyl (COOH), or various alkyl (CHn). This
variety of side chain groups on the polymer backbone gives proteins remarkable chemical and physical
properties. For example, carboxylate groups can function as carboxylic acids (COO-), or amino groups
can behave as bases (NH3+). This allows protein polymers to be multifunctional molecules, with both
acidic and basic behavior at the same time! Additionally, the presence of hydroxyls, carboxylates,
sulfhydryls, and amino groups allows hydrogen bonding, and the alkyl groups provide hydrophobic
interactions, both within the protein polymer itself and between separate protein molecules.
In the case of macromolecules, such as proteins, the polymeric structure of the macromolecule
allows it to simultaneously carry many different charges (on different amino acid residues). However,
unlike the small single molecules, the amino acid residues are constrained by linear peptide linkages and
thus cannot move freely to randomly associate with other charged molecules. Assuming that charged
residues will seek to bond with the nearest convenient counter ion, it is most likely that oppositely
charged amino acid residues located at different points within a single protein chain will bond. These
structural differences result in the folding of proteins into a three-dimensional structure, which is, in part,
responsible for their functional properties as biocatalysts, structural materials, muscles, and chemical
receptors. Proteins can be shaped as long flat sheets or in globular spheres. This leads to the names
fibrous or globular for protein shapes. Most enzymes are globular proteins.
In standard acid base chemistry, we know that molecules carry electrostatic charges based on the
type of atoms that make up a molecule and the environment of the molecule. Given that opposite charges
attract, cationic and anionic atoms can combine to form covalent bonds, in which electrons are shared
between atomic orbitals, or form ionic bonds, in which only electrostatic attractions exist. In solution with
smaller molecules, such as HCl (an acid) or NaOH (a base), protein molecules can freely move around
and associate with each other on a more-or-less random basis.
Protein polymers extend the simple acid base charged chemical species concepts to explain how
biological systems have greater levels of complexity and can utilize simple, monomeric chemical
structures (like amino acids) to create exquisitely complex biological structures like antibodies, muscle,
and skin. Protein polymers have physical structure, even when dissolved in liquids. The charged and
hydrophobic residues within a protein tend to associate, causing the protein to fold up. When you unfold

the protein molecule (called denaturation), its charged residues can reassociate with other charged
molecules (precipitation or coagulation). Protein precipitation is widely used to recover recombinant
protein products, enzymes, or in the production of many common foods. Cheeses and soybean tofu are
examples of coagulated protein food products.
Food Uses of Proteins
Proteins also serve important roles in the processing of food products. They are used for their
thickening, gelling, emulsifying, and water-binding properties in meats (sausages), bakery products,
cheese, desserts, and salad dressings. Proteins are used for their cohesive and adhesive properties in
sausage making, pasta, and baked goods. Egg proteins are used for their foaming properties in desserts,
cakes, and whipped toppings. Milk, egg, and cereal proteins are used as fat and flavor binders in low-fat
bakery products. Proteins are used for texture and palatability in bakery products (breads, cakes, crackers,
and pizza crust) and sausages.
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Milk protein consists of 80% casein and 20% whey proteins. There are four major types of casein
molecules: alpha-s1, alpha-s2, beta, and kappa. Milk, in its natural state, is negatively charged. The
negative charge permits the dispersion of casein in the milk. When an acid is added to milk, the H+
concentration neutralizes the negatively charged casein micelles. When milk is acidified to pH 4.7, the
isoelectric point (the point at which all charges are neutral) of casein, an isoelectric precipitate known as
acid casein is formed. Cottage cheese and cream cheese manufacture involves an acid precipitation of
casein with lactic acid or lactic acid producing microorganisms. Acid casein is used in the chemical
industry and as a glazing additive in paper manufacturing.
Casein also can be coagulated with the enzyme rennin, which is found in rennet (an extract from
the stomach of calves). Rennin works best at body temperature (37°C). If the milk is too cold, the reaction
is very slow, and if the milk is too hot, the heat will denature the rennin, rendering it inactive. The
mechanism for the coagulation of the casein by the rennin is different from the acid precipitation of

casein. The rennin coagulum consists of casein, whey protein, fat, lactose, and the minerals of the milk,
and has a fluffier and spongier texture than the acid precipitate. Rennet is used in the manufacture of
cheese and cheese products, and rennet casein is used in the plastics industry. Casein is solubilized with
sodium hydroxide and calcium hydroxide to produce sodium caseinate and calcium caseinate,
respectively. Caseinates are added to food products to increase their protein content and are key
ingredients in non-dairy coffee creamers.
Approximately 90% of soybean proteins are classified as globulins, based on their solubility in
salts. More specifically, the proteins are conglycinin (a glycoprotein) and glycinin. Tofu is manufactured
by coagulating the proteins in soymilk with magnesium sulfate. As bonding occurs between the positively
charged magnesium ions and negatively charged anionic groups of the protein molecules, the proteins
coagulate.
QUESTIONS
1. What are proteins?
2. Why are proteins important group of molecules?
3. Describe a basic structure of amino acid.
4. What does essential amino acid mean?
5. How are amino acids linked together in protein molecule?
6. Distinguish the terms ―peptides‖ and ―polypeptides‖
7. What are the important roles of protein in the processing of food products?
8. What is rennin? For what reason we utilized rennin in cheese processing?
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UNIT 6: ENZYMES
Living systems contain large protein molecules called enzymes. Those large globular proteins
range in molecular weight from about 10,000 to several million. Each of the thousands of known enzymes
has a characteristic three- dimensional shape with a specific surface configuration as a result of its
primary, secondary, and tertiary structures. The unique configuration of each enzyme enables it to ―find‖
the correct substrate from among the large number of diverse molecules in the cell.
Although some enzymes consist entirely of proteins, most consist of both a protein portion called
an apoenzyme and a nonprotein component called a cofactor. Together, the apoenzyme and cofactor form

a holoenzyme, or whole enzyme. If the cofactor is removed, the apoenzyme will not function. The
cofactor can be a metal ion or a complex organic molecule called a coenzyme. Coenzymes may assist the
enzyme by accepting atoms removed from the substrate or by donating atoms required by the substrate.
Some coenzymes act as electron carries, removing electrons from the substrate and donating them to other
molecules in subsequent reactions. Many coenzymes are derived from vitamins.
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The name of enzymes usually end in –ase. All enzymes can be grouped into six classes, according
to the type of chemical reaction they catalyze. Enzymes within each of the major classes are named
according to the more specific types of reactions they assist. They are:
1. Oxidoreductase: oxidation-reduction in which oxygen and hydrogen are gained or lost.
2. Transferase: Transfer of functional groups, such as an amino group, acetyl group, or phosphate
group
3. Hydrolase: hydrolysis (addition of water)
4. Lyase: removal of groups of atoms without hydrolysis
5. Isomerase: Rearrangement of atoms within a molecule
6. Ligase: joining of two molecules (using energy usually derived from break down of ATP)
Mechanism of Enzymatic Action
Enzymes can speed up chemical reaction in several ways. Whatever the method, the result is that
the enzyme lowers the activation energy for the reaction without increasing the temperature or pressure
inside the cell. Although scientists do not completely understand how enzymes lower the activation
energy of chemical reaction, the general sequence of events in enzyme reaction is as follows:
1. The surface of the substrate contacts a specific region of the surface of the enzyme molecule,
called the active site.
2. A temporary intermediate compound forms, called an enzyme-substrate complex.
3. The substrate molecule is transformed by the rearrangement of existing atoms, the breakdown of

the substrate molecule, or combination with another substrate molecule.
4. The transformed substrate molecules – the products of the reaction – are released from the enzyme
molecule because they no longer fit in the active site of the enzyme.
5. The unchanged enzyme is now free to react with other substrate molecules.
Enzymes are extremely efficient. Under optimum conditions, they can catalyze reaction at rates
108 to 1010 times (up to 10 billion times) higher than those of comparable reactions without enzymes.
In living cells, enzymes serve as biological catalysts. As catalysts, enzymes are specific. Each acts
on a substrate (or substrates, when there are two or more reactants), and each catalyzes only one reaction.
For example, a specific enzyme may be able to hydrolyze a peptide bond only between two specific
amino acids. Other enzymes can hydrolyze starch but not cellulose; even though both starch and cellulose
are polysaccharides composed of glucose subunits, the orientation of the subunits in the two
polysaccharides differ. Enzymes have this specificity because the three dimensional shape of the active
site fits the substrate somewhat as a lock fits with its key. However, the active site and substrate are
flexible, and they change shape somewhat as they meet to fit together more tightly. The substrate is
usually much smaller than the enzyme, and relatively few of the enzyme’s amino acids make up the active
site.
A certain compound can be a substrate for a number of different enzymes that catalyze different
reactions, so the fate of a compound depends on the enzymes that acts upon it. Glucose 6-phosphate, a
molecule that is important in cell metabolism, can be acted upon by at least four different enzymes, and
each reaction will yield a different product.
Factors influence enzyme activity
Several factors influence the activity of enzyme. The more important are temperature, pH,
substrate concentration, and presence or absence of inhibitors.
The rate of most chemical reactions increases as the temperature increases. Molecules move more
slowly at lower temperatures than at higher temperatures and so may not have enough energy to cause a
chemical reaction. For enzymatic reactions, however, elevation beyond a certain temperature drastically
reduces the rate of reaction. This decrease is due to the enzyme’s denaturation, the loss of its
characteristic three-dimensional structure (tertiary configuration). Denaturation of a protein involves
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breakage of hydrogen bonds and other noncovalent bonds. As might be expected, denaturation of an
enzyme changes the arrangement of the amino acids in the active site, altering its shape and causing the
enzyme to lose its catalytic ability. In some cases, denaturation is partially or fully reversible. However, if
denaturation continues until the enzyme has lost its solubility and coagulates (as with cooked albumin) the
enzyme cannot regain its original properties. Enzymes can be denatured by concentrated acids, bases,
heavy-metal ions (such as lead, arsenic, or mercury), alcohol, and ultraviolet radiation.
Most enzymes have an optimum pH at with their activity is characteristically maximal. Above or
bellow this pH value, enzyme activity, and therefore the reaction rate, declines. When the H +
concentration (pH) in the medium is changed, many of the enzyme’s amino acids are effected and the
protein’s three-dimensional structure is altered. Extreme changes in pH can cause denaturation.
There is a maximum rate at which a certain amount of enzyme can catalyze a specific reaction.
Only when the concentration of substrate(s) is extremely high can this maximum rate be attained. Under
condition of high substrate concentration, the enzyme is said to be saturation; that is, its active site is
always occupied by substrate or product molecules. In this condition, a further increase in substrate
concentration will not effect the reaction rate because all active sites are already in use. If a substrate’s
concentration exceeds a cell’s saturation level for a particular enzyme, the rate of reaction can be
increased only if the cell produces additional enzyme molecules. However, under normal cellular
conditions, enzymes are not saturated with substrate(s). At any given time, many of the enzyme molecules
are inactive for lack of substrate; thus, the rate of reaction is likely to be influenced by the substrate
concentration.
Enzyme inhibitors are classified according to their mechanism of action as either competitive or
noncompetive inhibitors. Competitive inhibitors fill the active site of an enzyme and compete with the
normal substrate for the active site. A competitive inhibitor is able to do this because its shape and
chemical structure are similar to those of normal substrate. However, unlike the substrate, it does not
undergo any reaction to form products. Some competitive inhibitors bind irreversibly to amino acids in
the active site, preventing any further interactions with the substrate. Others bind reversibly, alternately

occupying and leaving the active site, these slow the enzyme’s interaction with the substrate. Reversible
competitive inhibition can be overcome by increasing the substrate concentration. As active site becomes
available, more substrate molecules than competitive inhibitor molecules are available to attach to the
active sites of enzymes. Noncompetitive inhibitors do not compete with the substrate for the enzyme’s
active site; instead, they interact with another part of the enzyme. In this process, called allosteric (―other
space‖) inhibition, the inhibitor binds to a site on the enzyme other than the substrate’s binding site. This
binding causes the active site to change its shape, making it nonfunctional. As a result, the enzyme’s
activity is reduced. This effect cab be reversible or irreversible, depending on whether or not the active
site can return to its original shape. In some cases, allosteric interaction can activate an enzyme rather
than inhibit it. Another type of noncompetitive inhibition can operate on enzymes that require metal ions
for their activity. Certain chemical can bind or tie up the metal ion activators and thus prevent an
enzymatic reaction. Cyanide can bind the iron in iron-containing enzymes, and fluoride can bind calcium
or magnesium. Substances such as cyanide and fluoride are sometimes called enzyme poisons because
they permanently inactivate enzymes.
QUESTIONS:
1. What do enzymes generally consist of?
2. What can the cofactor be?
3. How do coenzymes work?
4. What is the important role of enzyme?
5. Describe the general sequence of events in enzyme reaction.
6. Why enzymes have their own specificity?
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7. Can a certain compound be a substrate for a number of different enzymes that catalyze different
reactions?
8. What are the important factors that influence the activity of enzyme?

9. What does denaturation of a protein involve?
10. What does denaturation of an enzyme cause?
11. By what factors can arrangement enzymes be denatured?
12. When the enzyme is said to be saturation?
13. How are enzyme inhibitors classified?
14. Are substrate’s shape and chemical structure similar to those of competitive or noncompetive
inhibitors?
15. What do competitive inhibitors do?
16. What is the difference between competitive inhibitors and noncompetitive inhibitors?
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UNIT 8: STERILIZATION VERSUS PASTEURIZATION
Thermal processing covers the broad area of food preservation technology in which heat
treatments are used to inactivate microorganisms to accomplish either commercial sterilization or
pasteurization. Sterilization processes are used with canning to preserve the safety and wholesomeness of
ready-to-eat foods over long terms of extended storage at normal room temperature (nonrefrigerated)
without additives or preservatives, and pasteurization processes are used to extend the refrigerated storage
life of fresh foods. Although both processes make use of heat treatments for the purpose of inactivating
microorganisms, they differ widely with respect to the classification or type of microorganisms targeted,
and thus the range of temperatures that must be used and the type of equipment systems capable of
achieving such temperatures.
SECTION I:
PASTEURIZATION
Pasteurization is a relatively mild heat treatment given to foods with the purpose of destroying
selected vegetative microbial species (especially the pathogens) and inactivating the enzymes. Because
the process does not eliminate all the vegetative microbial population and almost none of the spore
formers, pasteurized foods must be contained and stored under conditions of refrigeration with chemical
additives or modified atmosphere packaging, which minimize microbial growth. Depending on the type of
product, the shelf life of pasteurized foods could range from several days (milk) to several months (fruit
juices). Because only mild heat treatment is involved, the sensory characteristics and nutritive value of the

food are minimally affected. The severity of the heat treatment and the length of storage depend on the
nature of the product, pH conditions, the resistance of the target microorganism or enzyme, the sensitivity
of the product, and the method of heating.
Most pasteurization operations involving liquids (milk, milk products, beer, fruit juices, liquid
egg, etc) are carried out in continuous heat exchangers. The product temperature is quickly raised to the
pasteurization levels in the first heat exchanger, held for the required length of time in the holding tube,
and quickly cooled in a second heat exchanger. For viscous fluids, a swept surface heat exchanger is often
used to promote faster heat transfer and to prevent surface fouling problems. In-package pasteurization is
similar to conventional thermal processing of foods except that it is carried out at lower temperatures. The
thermal processing of high acid foods (natural or acidified) is also sometimes termed pasteurization to
indicate that relatively milder heat treatment is involved (generally carried out at boiling water
temperatures).
SECTION II:

STERILIZATION

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Sterilization implies the destruction of all viable microorganisms and is not the appropriate word
to be used for thermal processing of foods, because these foods are far from being sterile in the medical
sense of the word. The success of thermal processing does not lie in destroying all viable microorganisms
but in the fact that together with the nature of the food (pH), environment (vacuum), hermetic packaging,
and storage temperature, the given heat process prevents the growth of microorganisms of spoilage and
public health concern. In essence, it presents a thermal process in which foods are exposed to a highenough temperature for a sufficiently long time to render them commercially sterile. The process takes
into account the heat resistance of the spore formers in addition to their growth sensitivity to oxygen, pH,
and temperature. The presence of vacuum in cans prevents the growth of most aerobic microorganisms,

and if the storage temperature is kept below 250C, the heat-resistant thermopiles pose little or no problem.
From the public health perspective, the most important microorganism in low-acid (pH > 4.5) foods is
Clostridium botulinum, a heat-resistant, spore-forming, anaerobic pathogen that, if it survives processing,
can potentially grow and produce the deadly botulism toxin in foods. Because C. botulinum and most
spore formers do not grow at pH < 4.5 (acid and medium-acid foods), the thermal processing criterion for
these foods is the destruction of heat-resistant yeasts and molds, vegetative microorganisms, or enzymes.
Because spore formers generally have high heat resistance, the low-acid foods that support their growth
are processed at elevated temperatures (115-1250C), whereas acid foods need only to be brought to 80900C for adequate inactivation of enzymes or destruction of vegetative cells, yeasts, and molds.
QUESTIONS
1.
2.
3.
4.
5.

What is the difference between sterilization and pasteurization?
The main purpose of sterilization and pasteurization.
Are spore –former microorganisms destroyed in pasteurization?
Can pasteurized foods be preserved in normal storage condition?
Does the pasteurization process affect greatly the sensory characteristics and nutritive value of the
food?
6. Are enzymes inactivated in the pasteurization process?
7. Give example of food products which is treated by pasteurization
8. Describe the stages in the pasteurization process.
9. What is the equipment for holding the pasteurization temperature called?
10. What does the term ―pasteurization‖ mean for heat treatment of high acid foods?
11. Are all viable microorganisms destroyed by sterilization or pasteurization?
12. What microorganism is considered as the most important in terms of public health concern,
especially in low acid foods ? Why?
13. What are the ph values for low-acid and acid foods?

14. What target microorganisms are destroyed by heat processing for acid foods?
15. Why is temperature requirement of thermal processing for acid foods lower than for low acid
foods?
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UNIT 9: MAKING PEANUT BUTTER
The first step in making peanut butter is growing the peanuts, of course!
From the harvest the nuts go to shelling operations. These plants, located near the growing fields,
remove the shells, clean the nuts, and pack them into huge bags for shipment to the peanut butter plant.
Each bag holds more than 2,000 pounds of peanuts!
At the plant, the bags are unloaded into bucket conveyors that move the nuts from each processing
step to the next one. The first step is to insure that all impurities, such as stems and sticks from the peanut
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plants, are removed from the product stream. This is done by gravity separators, which sort out objects
that are heavier or lighter than peanuts.
The peanuts are now ready for roasting. This is done by a continuous roaster. The nuts are slowly
carried through the roaster on a belt while hot air is circulated. It is extremely important that the nuts be
roasted evenly and properly so that flavor and color are just right. The roaster operator adjusts the roast as
required by changing the air temperature, belt speed or peanut layer thickness on the belt.
The peanuts are cooled and conveyed to the blanching machines, which remove the skins. This
prevents the peanut butter from having dark specks from the skins.
The last step before the peanuts can be ground into peanut butter is the final inspection for quality.
The nuts are conveyed through an electronic color sorter which removes nuts that were under or over
roasted. The peanuts also pass a trained inspector who looks them over and picks out any that do not look
right.

The peanuts are now ready to be conveyed to the grinders. (If we are making 'chunky' peanut
butter, some of the nuts are diverted to a chopper, and are then added back to the peanut butter just before
filling the jars.) The grinders are like giant milkshake machines.
Although peanut butter consists of mostly peanuts (at least 90%), small amounts of other
ingredients are added while the nuts are being ground. In the case of 'old fashioned' peanut butter, we add
a little bit of salt for flavor and a special vegetable oil called a stabilizer. This keeps the peanut oil from
separating out to the top of the jar.
At this point the peanut butter is pumped through a metal detector to insure that no metal got into
it during the grinding. Then it is pumped into a deaerator, which removes trapped air. Finally, the peanut
butter, quite hot from all that grinding, passes through a heat exchanger to cool it down so it can be
packed into containers on the filling line.
The filling machine is carefully timed to put the correct amount of peanut butter in each jar. The
jar then is conveyed to the capping machine.
Capped jars are sent through an induction sealer, which seals the inner liner to the top of the jar.
Then, another machine applies the label to the jar.
The jars are now ready for packing into the shipping case. This is done by hand so that the packer
can inspect each jar's label and general appearance.
All that's left is to glue the cases closed and put the peanut butter in the warehouse, then wait a few
days before shipping it to the stores. This allows for 'microbiological tests to make sure no molds or
bacteria have found their way into the peanut butter. After the tests come back 'clean' we can release it for
our customers to enjoy.
QUESTIONS:
1. What are the major processing steps in producing peanut butter?
2. What are the reasons for roasting peanuts?
3. What is the important consideration one should be taken during roasting step?
4. Why do we often add vegetable oil to peanut butter?
5. Why the peanut butter is pumped through a metal detector after grinding?
6. Why do we have to keep peanut butter jars at warehouse a few days before shipping them to the
stores?
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UNIT 10: BREAD PREPARATION
Preparing bread involves many ingredients and advance preparation steps. Flour is received by
bulk rail or truck and stored in 100,000 pound bins. All other raw materials are received by truck. Two
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hours before production begins, a liquid sponge or broth is prepared and allowed to ferment to ensure that
the finished loaf will rise properly. The broth is a blend of flour, water, sugar, salt, yeast and yeast foods.
To combine the ingredients necessary for bread making, a scaler measures out the smaller
increments of the mix, some as little as one ounce. A dough mixer operated by a control panel takes the
ingredients from the scaler and adds the larger increments to the mix to create the proper dough
consistency.
This mixture can weigh anywhere from 400 to 2,000 pounds. The dough is then 'kicked' out of the
mixer into a trough and allowed to 'relax' and ferment. This is called floortime. Then it goes to a hopper
and is divided into loaf-sized pieces, then to the rounder for shaping.
Once again the dough is set aside in an overhead proofer to relax and continue fermenting for
approximately 10 minutes. The dough is then sent to the head rollers for flattening and removal of excess
air. This is a key step in bread making. Removing excess fermenting gas helps ensure good inner structure
and grain in the finished loaf.
The next stop is the moulder, where the bread is shaped for the final baking process. The moulder
is also helpful in removing air from the dough. Once molded, the bread is dropped into a large pan
divided into five separate loaf pans. These pans travel along a conveyor to another proof box. Here they
will stay for 55 minutes. The temperature in the proof box is monitored closely to maintain 90% humidity
level and 105º temperature level at all times.
Now the bread is sent to the ovens for baking. The oven temperatures and baking times will vary
as to size and density of the loaf. The loaves bake for 22 minutes at approximately 400º. The baked bread

is conveyed to a depanner. This is just what it sounds like; suction cups and vacuum pressure remove the
baked loaf from the pan. The pan is sent back to storage to be used again, and the loaf is sent to cool.
The bread cools for about an hour and is then sent to be sliced. Once sliced, the bread is wrapped
by an automatic bagging machine. Now that the loaf is in the bag, it is sent to be tied and fastened. The
finished product is conveyed to where it is sorted and stacked for store distribution. Total production time
for a loaf of bread is about three hours. The total lapsed time from the beginning of production to when
the bread is on the shelf in the store is 24 hours.
QUESTIONS:
1. What are the major processing steps in preparing bread?
2. Definition the term ―a liquid sponge‖ or ―broth‖ in bread preparation.
3. What does a broth consist of?
4. What is floortime in bread preparation?
5. What do baking temperatures and times depend on?
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UNIT 12: MILK PROCESSING
Milk fresh from the cow is virtually a sterile product. All post-milking handling must maintain the
milk's nutritional value and prevent deterioration caused by numerous physical and biological factors. In
addition, equipment on the farm must be maintained to government and industry standards. Most cows are
milked twice a day, although some farms milk three or four times per day. The milk is immediately
cooled from body temperature to below 40°F (5°C), then stored at the farm under refrigeration until
picked up by insulated tanker trucks at least every other day. The milk tanker driver records the amount of
milk and notes the temperature and the presence of any off-odors. If the milk is too warm or has an offodor, it will not be picked up, and the farmer will have to feed it to his animals or dump it. When the milk
is pumped into the tanker, a sample is collected for later lab analysis.
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When the milk arrives at the milk plant, it is checked to make sure it meets the standards for
temperature, total acidity, flavor, odor, tanker cleanliness, and the absence of antibiotics. The butterfat and
solids-not-fat content of this raw milk is also analyzed. The amounts of butterfat (BF) and solids-not-fat
(SNF) in the milk will vary according to time of year, breed of cow, and feed supply. Butterfat content,
solids-not-fat content, and volume are used to determine the amount of money paid the farmer.
Once the load passes these receiving tests, it is then pumped into large refrigerated storage silos
(nearly half-million pounds capacity) at the processing plant.
All raw milk must be processed within 72 hours of receipt at the plant. Milk is such a nutritious
food that numerous naturally occurring bacteria are always present. The milk is pasteurized, which is a
process of heating the raw milk to kill all "pathogenic" bacteria that may be present. A pathogen is a
bacteria that could, if allowed to grow and multiply, make humans sick. It should be noted that
pasteurization is not sterilization (sterilization eliminates all viable life forms, while pasteurization does
not). After pasteurization, some harmless bacteria may survive the heating process. It is these bacteria that
will cause milk to "go sour." Keeping milk refrigerated is the best way to slow the growth of these
bacteria. Some bacteria do not cause spoilage, but are actually added to milk or cream after pasteurization
to make "cultured" products such as cheese, cottage cheese, yogurt, buttermilk, acidophilus milk and sour
cream.
There are different ways to pasteurize milk. The "batch" method heats the milk to at least 145° and
holds it at that temperature for at least 30 minutes.
Since this method may cause a "cooked" flavor, it is not used by some milk plants for fluid milk
products.
High Temperature/Short Time (HTST) pasteurization heats the milk to at least 161° for at least 15
seconds. The milk is immediately cooled to below 40° and packaged into plastic jugs or plastic-coated
cartons. Most milk plants have at least one HTST processor. This piece of equipment is considered the
"heart" of the plant.
Butterfat content accounts for several different types of products. Whole milk, 2%, 1%, Nonfat,
and Half & Half are some examples. A machine called a separator separates the cream and skim portions
of the milk. A separator is really a large centrifuge that spins about 2,000 rotations per minute. The
different types of milk products are then "standardized" by blending the components (skim milk, raw
milk, cream) in the correct proportions to yield the desired end-products. Water is never added to lower

the butterfat content of fluid milk. Excess cream is used to make ice cream and butter.
Milk is homogenized to prevent the cream portion from rising to the top of the package. The
expression "cream rises to the top," is accurate because cream is lighter in weight than milk. The cream
portion of un-homogenized milk would form a cream layer at the top of the carton. A "homogenizer"
forces the milk under high pressure through a valve that breaks up the butterfat globules to such small
sizes they will not "coalesce" (stick together). Homogenization does not affect the nutrition or quality of
the product; it is done entirely for aesthetic purposes.
Vitamin quantities may be reduced by the heating process and removal of the butterfat. Therefore,
to replace the natural nutrition of nature's perfect food, liquid vitamins are added to fortify most fluid milk
products. Many states have milk standards that require the addition of milk solids. These solids represent
the natural mineral (i.e. calcium, iron), protein (casein), and sugar (lactose) portion of nonfat dry milk.
You will see this shown as an ingredient on those products needing fortification.
Quality Control personnel conduct numerous tests on the raw and pasteurized products to insure
optimum quality and nutrition. A sample is analyzed for the presence of microbiological organisms with a
standard plate count (SPC) and ropey milk test. The equipment used to analyze butterfat and solids-not-fat
is calibrated on a regular basis to insure a consistent, quality product that meets or exceeds government
requirements.
All milk products have a sell-by date printed on the package. This is the last day the item should
be offered for sale. However, most companies guaranty the quality and freshness of the product for at
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least 7 days past the date printed on the package. Samples of each product packaged each day are saved to
confirm that they maintain their freshness 7 days after the sell-by date.
Once the milk has been separated, standardized, homogenized and pasteurized, it is held below
40°F in insulated storage tanks, then packaged into gallon, half-gallon, quart, pint, and half-pint
containers. The packaging machines are maintained under strict sanitation specifications to prevent

bacteria from being introduced into the pasteurized product. All equipment that comes into contact with
product (raw or pasteurized) is washed daily. Sophisticated automatic Clean-in-Place (CIP) systems
guarantee consistent sanitation with a minimum of manual handling, reducing the risk of contamination.
Once packaged, the products are quickly conveyed to a cold storage warehouse. They are stored
there for a short time and shipped to the supermarket on refrigerated trailers. Once at the store, the milk is
immediately placed into a cold storage room or refrigerated display case.
QUESTIONS:
1. What are requirements for handling fresh milk?
2. Which parameters must be checked when receiving raw milk at factory?
3. Explain the difference between pasteurization and sterilization.
4. Explain the difference between the batch and the HTST method of pasteurization.
5. For what reason do we homogenize milk?
6. What is SPC abbreviated for?
7. What is CIP abbreviated for?
8. What is HTST abbreviated for?
9. What is BF abbreviated for?
10. What is SNF abbreviated for?
11. What is a sell-by date?

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UNIT 13: THE BISCUIT INDUSTRY
WHAT ARE BISCUITS?
Biscuits are small baked products made principally from flour, sugar and fat. They typically have
a moisture content of less than 4% and when packaged in moisture-proof containers have long shelf lives,
perhaps six months or more. The appeal to consumers is determined by the appearance and eating
qualities. For example, consumers do not like broken biscuits nor ones that have been over or under
baked.
Biscuits are made in many shapes and sizes and after baking they may be coated with chocolate,
sandwiched with a fat-based filling or have other pleasantly flavored additions.

HOW ARE BISCUITS MADE?
Biscuits are a traditional type of flour confectionery which were, and can still be, made and baked
in a domestic kitchen. Now they are made mostly in factories on large production plants. These plants are
large and complex and involve considerable mechanical sophistication. Forming, baking and packaging
are largely continuous operations but metering ingredients and dough mixing are typically done in
batches.
There is a high degree of mechanization in the biscuit industry but at present there are very few
completely automatic production plants. This means that there is a high degree of dependence on the
operators to start and control production plant. It is essential that operators are skilled in the tasks they
have to do and this involves responsibility for product quality. As part of their training they must know
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about the ingredients and their roles in making biscuits. They must be aware of the potential ingredient
quality variations and the significance of these.
There are basically two types of biscuit dough, hard and soft. The difference is determined by the
amount of water required to make dough which has satisfactory handling quality for making dough pieces
for baking.
Hard dough has high water and relatively low fat (and sugar) contents. The dough is tough and
extensible (it can be pulled out without immediately breaking), like tight bread dough. The biscuits are
either crackers or in a group known as semi-sweet or hard sweet.
Soft doughs contain much less water and relatively high levels of fat and sugar. The dough is
short, (breaks when it is pulled out) which means that it inhibits very low extensible character. It may be
soft that it is pourable. The biscuits are of the soft eating types which are often referred to as ―cookies‖.
There are a great number of biscuit types made from soft doughs and a wide variety of ingredients may be
used.
The machinery used to make biscuits is designed to suit the type of dough needed and to develop

the structure and shape of the individual biscuits.
Secondary processing, which is done after the biscuit has been baked, and packaging of biscuits
are specific to the product concerned. There is normally a limited range of biscuit types that can be made
by given set of plant machinery.
Many biscuit production plants bake at the rate of 1000-2000 kg per hour and higher rates are not
unusual. Given this and the sophistication of the production line it is most economical to make only one
biscuit type for a whole day or at least an eight hour shift.
QUESTIONS
1.
2.
3.
4.

Which ingredients are biscuits made from?
What moisture do biscuits typically have?
In terms of packaging, how is the shelf life of biscuits prolonged?
Due to a high degree of mechanization in the biscuit industry, how important is the role of the
operators?
5. What requirements do operators in biscuit production need to meet?
6. Describe the main differences between hard and soft dough.
7. What types of biscuit are referred to as ―cookies‖?
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UNIT 18: FOOD PRESERVATION
Food preservation is the process of treating and handling food in such a way as to stop or greatly
slow down spoilage to prevent foodborne illness while maintaining nutritional value, texture and flavor.
Preservation usually involves preventing the growth of bacteria, fungi and other micro-organisms,
as well as retarding the oxidation of fat which cause rancidity. It also includes processes to inhibit natural
aging and discolouration that can occur during food preparation such as the polyphenoloxidase reaction in
apples which causes browning when apples are cut. Some preservation methods require the food to be

sealed after treatment to prevent re-contamination with microbes; others, such as drying, allow food to be
stored without any special containment for long periods.
Preservation processes include:
 Heating to kill or denature organisms (e.g. boiling)
 Oxidation (e.g use of sulphur dioxide)
 Toxic inhibition (e.g. smoking, use of carbon dioxide, vinegar, alcohol etc)
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




Dehydration (drying)
Osmotic inhibition ( e.g use of syrups)
Low temperature inactivation (e.g. freezing)
Many combinations of these methods
One of the oldest methods of food preservation is by drying, which reduces water activity
sufficient to delay or prevent bacterial growth. Most types of meat can be dried and this is especially
valuable in the case of pig meat since this is difficult to keep without preservation. Many fruits can also be
dried and the process is often applied to apples, pears, bananas, mangoes, papaya, coconut etc. Drying is
also the normal means of preservation for cereal grains such as wheat, maize, oats, barley, rice.
Probably as old as drying, many Arctic communities would preserve food in holes or larders dug
into the ice. There is a tradition in Scandinavia of preserving fish and especially herrings in this way.
Freezing is also one of the most commonly used processes commercially and domestically for preserving
a very wide range of food stuffs including prepared food stuffs which would not have required freezing in
their unprepared state. For example, potato waffles are stored in the freezer, but potatoes themselves

require only a cool dark place to ensure many months' storage. Cold stores provide large volume, longterm storage for strategic food stocks held in case of national emergency in many countries.
Canning involves cooking fruits or vegetables, sealing them in sterile cans or jars, and boiling the
containers to kill or weaken any remaining bacteria. Various foods have varying degrees of natural
protection against spoilage and may require that the final step occur in a pressure cooker. High-acid fruits
like strawberries require no preservatives to can and only a short boiling cycle, whereas marginal fruits
such as tomatoes require longer boiling and addition of other acidic elements. Many vegetables require
pressure canning. Food preserved by canning or bottling is at immediate risk of spoilage once the can or
bottle has been opened. Lack of quality control in the canning process may allow ingress of water or
micro-organisms. Most such failures are rapidly detected as decomposition within the can causes gas
production and the can will swell or burst. However, there have been examples of poor manufacture and
poor hygiene allowing contamination of canned food by the obligate anaerobe, Clostridium botulinum
which produces an acute toxin within the food leading to severe illness or death. This organism produces
no gas or obvious taste and remains undetected by taste or smell.
Pickling is a method of preserving food by placing it or cooking it in a substance that inhibits or
kills bacteria and other micro-organisms. This material must also be fit for human consumption. Typical
pickling agents include brine (high in salt), vinegar, ethanol, and vegetable oil, especially olive oil but
also many other oils. Most pickling processes also involve heating or boiling so that the food being
preserved becomes saturated with the pickling agent. Frequently pickled items include vegetables such as
cabbage, peppers, and some animal products such as corned beef and eggs.
Vacuum-packing stores food in a vacuum environment, usually in an air-tight bag or bottle. The
vacuum environment strips bacteria of oxygen needed for survival, hence preventing the food from
spoiling. Vacuum-packing is commonly used for storing nuts.
Modified atmosphere is a way to preserve food operating on the atmosphere around it. Salad crops
which are notoriously difficult to preserve are now being packaged in sealed bags with an atmosphere
modified to reduce the oxygen concentration and increase the carbon dioxide concentration. There is
concern that although salad vegetables retain their appearance and texture in such conditions, this method
of preservation may not retain nutrients, especially vitamins. Grains may be preserved using carbon
dioxide. A block of dry ice is placed in the bottom and the can is filled with grain. The can is then
"burped" of excess gas. The carbon dioxide from the sublimation of the dry ice prevents insects, mold,
and oxidation from damaging the grain. Grain stored in this way can remain edible for five years.

Some foods, such as many traditional cheeses, will keep for a long time without use of any special
procedures. The preservation occurs because of the presence in very high numbers of beneficial bacteria
or fungi which use their own biological defences to prevent other organisms gaining a foot-hold.
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Sugar is used to preserve fruits, either in syrup with fruit such as apples, pears, peaches, apricots,
plums or in crystalized form where the preserved material is cooked in sugar to the point of crystalization
and the resultant product is then stored dry. This method is used for the skins of citrus fruit (candied peel),
angelica and ginger. The use of sugar is often combined with alcohol for preservation of luxury products
such as fruit in brandy or other spirits.
Food may be preserved by cooking in a material that solidifies to form a gel. Such materials
include gelatine, agar, maize flour and arrowroot flour. Some foods naturally form a protein gel when
cooked.
QUESTIONS:
1. What is food preservation?
2. What is foodborne illness?
3. What do preservation processes include?
4. How can drying method preserve foods?
5. What is the role of cold stores in food preservation?
6. What is pickling method?
7. How can grains be preserved by using modified atmosphere?
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UNIT 19: FOOD PACKAGING
Food packaging development started with humankind’s earliest beginnings. Early forms of
packaging ranged from gourds to sea shells to animal skin. Later came pottery, cloth and wooden

containers. These packages were created to facilitate transportation and trade.
Utilizing modern technology, today’s society has created an overwhelming number of new
packages containing a multitude of food products. A modern food package has many functions, its main
purpose being to physically protect the product during transport. The package also acts as a barrier against
potential spoilage agents, which vary with the food product. For example, milk is sensitive to light;
therefore, a package that provides a light barrier is necessary. The milk carton is ideal for that. Other
foods like potato chips are sensitive to air because the oxygen in the air causes rancidity, which is a
condition of spoiled oil characterized by objectionable odor and flavor. The bags containing potato chips
are made of materials with oxygen- barrier properties. Practically all foods should be protected from filth,
microorganisms, moisture and objectionable odors. We rely on the package to offer that protection.
Aside from protecting the food, the package serves as a vehicle through which the manufacturer
can communicate with the consumer. Nutritional information ingredients and often recipes are found on a
food label. The package is also utilized as a marketing tool designed to attract your attention at the store.
This makes printability an important property of a package.
The food industry utilizes four basic packaging materials: metal, plant matter (paper and wood),
glass and plastic. A number of basic packaging materials are often combined to give a suitable package.
The fruit drink box is an example where plastic, paper and metal are combined in a laminate to give an
ideal package. This concept can be easily seen in your peanut butter jar. The main package containing the
food (primary package) is made of glass (or plastic), the lid is made of metal lined with plastic, and the
label is made of paper.
Each basic packaging material has advantages and disadvantages. Metal is strong and a good
overall barrier, but heavy and prone to corrosion. Paper is economical and has good printing properties;
however, it is not strong and it absorbs water. Glass is transparent, which allows the consumer to see the
product, but breakable. Plastics are versatile but often expensive. Therefore, combining the basic
materials works well in most cases. So, for a product like milk, which is an essential food for children and
young adults and therefore cannot be very expensive, paper makes a good economical material. It also
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provides a good printing surface. However, since paper absorbs water, it will gain moisture from the milk,
get weaker and fail, thereby exposing the milk to spoilage factors. It may even break and waste the
product. When a thin layer of a plastic called polyethylene is utilized to line the inside of the milk carton,
it serves as a barrier to moisture and makes an economical, functional package.
After making a food product and placing it in the appropriate package, a number of these
individual packages must be placed in a large container to facilitate shipment. These larger containers are
called secondary packages. The paperboard box is a very common secondary package. Plastics also can
serve as secondary packages. The milk case in which a number of milk cartons are delivered to the
supermarket is a good example.
We cannot discuss food packaging without discussing the effects of packaging waste on the
environment. Clearly, recycling is a sound approach. However, the problem often lies in feasibility of
collection, separation and purification of the consumer’s disposed food packages. This mode of recycling
is called post-consumer recycling. While it offers a logistic challenge, recycling is gaining in popularity,
and the packaging industry is cooperating in that effort. Aluminum cans are the most recycled container at
this time. Plastic recycling is increasing, yet most plastic is recycled during manufacturing of the
containers; not as post-consumer recycling. For example, trimmings from plastic bottles are reground and
reprocessed into new ones.
The plastics industry is helping to facilitate consumer recycling by identifying the type of plastic
from which the container is made. A number from 1 to 7 is placed within the recycling logo on the
container’s bottom. For example, 1 refers to PET (Polyethylene Terephthalate), the plastic used for the
large 2 liter soft drink bottles. Plastics have the advantage of being light. This helps to conserve fuel
during transport and also reduces the amount of package waste.
There are many interesting packaging concepts being explored by the industry to keep up with the
changing life style of the consumer and new technologies. Many professionals are involved in designing
and manufacturing the modern package. Today's package is designed with the consumer's safety and
convenience in mind. Examples are microwaveable popcorn packages, squeezable ketchup bottles and the
tamper-proof milk bottle cap.
QUESTIONS

1. In term of packaging, what does barrier mean?
2. What does Primary Package mean?
3. What does Secondary Package mean?
4. What does Printability mean?
5. Explain about rancidity
6. What is PET abbreviated for?
7. What is PE abbreviated for?
8. What does laminated package mean?
9. What are the three basic packaging materials that make up the fruit drink box?
10. Which plastic is utilized to line the inside of the milk carton?
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