On food and cooking the science and lore of the kitchen ( PDFDrive ) 1151

desserts,and“shooters”fortifiedwithvodka
andotherspirits.Morerefinedpreparations,
oftennamedbytheFrenchgelée,take
advantageofthefactthatotheringredients
canbeaddedatthelastminutewhenthemix
isbarelywarmandabouttoset,sofreshand
delicateflavorscanbepreservedinthejelly:
suchthingsaschampagneorthe“water”from
aseededtomato.
Gelatin Production Most manufactured
gelatinintheUnitedStatesandEuropecomes
frompigskin,thoughsomeisalsomadefrom
cattle skins and from bones. Industrial
extractionisfarmoreefficientandgentleron
the gelatin chains than kitchen extractions.
Thepigskinsaresoakedindiluteacidfor18–
24hourstobreakthecollagen’scross-linking
bonds, and then are extracted in several
changes in water, beginning at just
130ºF/55ºC, and ending around 195ºF/90ºC.
The low-temperature extracts contain the


most intact gelatin molecules, produce the
strongest gels, and are the lightest in color;
higher temperatures damage more gelatin
chains and cause a yellow discoloration. The
extracts are then filtered, purified, their pH
adjusted to 5.5, evaporated, sterilized, and
driedintosheetsorgranulesthatare85–90%
gelatin, 8–15% water, 1–2% salts, and 1%

glucose. Gelatin quality is sometimes
indicated by a “Bloom” number (named for
Oscar Bloom, inventor of the measuring
device), with high numbers (250) indicating
highgellingpower.
Types of Gelatin Gelatin is sold in several
different forms. Granulated gelatin and sheet
gelatin are given an initial soaking in cold
water so that the solid gelatin network can
absorb moisture and dissolve readily when
warm liquid is added. If added to the warm
liquid directly, the outer layers of the solid
granules can become gluey and stick