4 Part I: Principles
universities in various countries now offer a gradu-
ate course in food biochemistry as an elective or
have food biochemistry as a specialized area of
expertise in their undergraduate and graduate pro-
grams. One of the reasons for not requiring such a
course at the undergraduate level may be that a bio-
chemistry course is often taken in the last two to
three semesters before graduation, and there is no
room for such a course in the last semesters. Also,
the complexity of this area is very challenging and
requires broader views of the students, such as those
at the graduate level. However, the importance of
food biochemistry is now recognized in the subdis-
cipline of food handling and processing, as many of
these problems are biochemistry related. A content-
specific journal, the Journal of Food Biochemistry,
has also been available since 1977 for scholars to
report their food biochemistry–related research
results, even though they can also report their find-
ings to other journals.
Understanding of food biochemistry followed by
developments in food biotechnology in the past
decades resulted in, besides better raw materials and
products, improved human nutrition and food safety,
and these developments are applied in the food
industry. For example, milk-intolerant consumers in
the past did not have the advantage of consuming
dairy products. Now they can, with the availability
of lactase (a biotechnological product) at the retail
level in some developed countries. Lactose-free milk
is also produced commercially in some developed
industrial countries. The socially annoying problem
of flatulence that results from consuming legumes
can be overcome by taking “Beano™” (alpha-galac-
tosidase preparation from food-grade Aspigillus
niger) with meals. Shark meat is made more palat-
able by bleeding the shark properly right after catch
to avoid the biochemical reaction of urease on urea,
both naturally present in the shark’s blood. Proper
control of enzymatic activities also resulted in better
products. Tomato juice production is improved by
proper control of its pectic enzymes. Better color in
potato chips is the result of control of the oxidative
enzymes and removal of substrates from the cut
potato slices. More tender beef is the result of prop-
er aging of carcasses and sometimes the addition of
protease(s) at the consumer level; although this
result had been observed in the past, the reasons
behind it were unknown. Ripening inhibition of
bananas during transport is achieved by removal of
the ripening hormone ethylene in the package to
minimize the activities of the ripening enzymes,
making bananas available worldwide all year round.
Proper icing or seawater chilling of tuna after catch
avoids/controls histamine production by inhibiting
the activities of bacterial histamine producers, thus
avoiding scombroid or histamine poisoning. These
are just a few of the examples that will be discussed
in more detail in this chapter and in the commodity
chapters in this book.
Problems due to biochemical causes are numer-
ous; some are simple, while others are fairly com-
plex. These can be reviewed either by commodity
group or by food component. This introductory
chapter takes the latter approach by grouping the
various food components and listing selected related
enzymes and their biochemical reactions (without
structural formulas) in tables and presenting brief
discussions. This will give the readers another way
of looking at food biochemistry, but as an introduc-
tion to the following material, effort is taken to avoid
redundancy with the chapters on commodities that
cover the related biochemical reactions in detail.
This chapter presents first selected biochemical
changes in the macrocomponents of foods (carbohy-
drates, proteins, and amino acids), then lipids, then
selected biochemical changes in flavors, plant pig-
ments, and other compounds important in food
handling and processing. Biotechnological develop-
ments as they relate to food handling and processing
are introduced only briefly, as new advances are
extensively reviewed in Chapter 3. As an example of
complexity in the food biochemistry area, a diagram
showing the relationship of similar biochemical re-
actions of selected food components (carbohy-
drates) in different commodities is presented. Ex-
amples of serial degradation of selected food
components are also illustrated with two other dia-
grams.
It should be noted that the main purpose of this
chapter is to present an overview of food biochem-
istry by covering some of the basic biochemical
activities related to various food components and
their relations with food handling and processing. A
second purpose is to get more students interested in
food biochemistry. Purposely, only essential refer-
ences are cited in the text, to make it easier to read;
more extensive listings of references are presented
at the ends of tables and figures. Readers should
refer to these references for details and also consult
the individual commodity chapters in this book (and
their references) for additional information.