On food and cooking the science and lore of the kitchen ( PDFDrive ) 1147
Bạn đang xem bản rút gọn của tài liệu. Xem và tải ngay bản đầy đủ của tài liệu tại đây (122.7 KB, 2 trang )
above 140ºF/60ºC or below 40ºF/5ºC to
prevent the growth of bacteria that can
cause food poisoning. When cooling large
quantities of meat stock, the cook should
dividethestockintosmallportionssothat
their temperature will fall rapidly through
the potentially dangerous temperature
range.
Like well-browned meats themselves,
meat stocks and sauces whose flavor
comes from browned pan juices or from
long reduction carry small quantities of
chemicals called heterocyclic amines.
HCAs are known to damage DNA and
therefore may contribute to the
development of cancer (p. 124). We don’t
yetknowwhetherthelevelsfoundinmeats
and sauces pose a significant risk.
Vegetables in the cabbage family contain
chemicals that prevent HCAs from
damaging DNA, so it may be that other
foods in a well-balanced diet protect us
fromthetoxiceffectsofHCAs.
JellyConsistency
Thefirmnessorstrengthofagelatingel,and
thereforeitstoleranceofhandlingandits
textureinthemouth,dependsonseveral
factors:thegelatinmoleculesthemselves,the
presenceofotheringredients,andthewayin
whichthemixtureiscooled.
Gelatin Quality and Concentration The
most important influence on the texture of a
jelly is the concentration and quality of its
gelatin. Gelatin is a highly variable material.
Even manufactured gelatin (below) is only
60–70% intact, full-length gelatin molecules;
the remainder consists of smaller pieces that
are less efficient thickeners. The gelatin in a
stock is especially unpredictable, since meat
and bones vary in their collagen content, and
longcookingcausesprogressivebreakdownof
