Food Biochemistry and Food Processing (2 edition)

(Steven Felgate) #1

BLBS102-c01 BLBS102-Simpson March 21, 2012 11:8 Trim: 276mm X 219mm Printer Name: Yet to Come


16 Part 1: Principles/Food Analysis

Table 1.11.Selected Commercial
Biotechnology-Derived Food Enzymes

Enzyme Application

Acetolactate decarboxylase
(EC 4.1.1.5)

Beer aging and diacetyl
reduction
α-Amylase (EC 3.2.1.1) High-fructose corn syrup
production
Amylo-1,6-glucosidase (EC
3.2.1.33)

High-fructose corn syrup
production
Chymosin (EC 3.4.23.4) Milk clotting in cheese
manufacturing
Lactase (EC 3.2.1.108) Lactose hydrolysis
Glucan-1,4-α-maltogenic
α-amylase (EC 3.2.1.133)

Anti-stalling in bread

Source: Roller and Goodenough 1999, Anonymous 2004, IUBMB-NC
website (www.iubmb.org).

with designations 4:0, 5:0 and 6:0, respectively, with the first
digit indicating the number of carbons and the second giving the
number of double bonds. For FAs containing double bonds, hex-
adecanoic acid (16:0) becomes hexadecenoic acid (16:1), 16:2 is
termed hexadecadienoic acid, indicating two double bonds, and
16:3 is hexadecatrienoic acid. Following this convention and in
order to indicate the position of the double bond, if 16:1 has its
double bond between C7 and C8, then 7-hexadecenoic acid is
used.
Currently, the term ‘omega’ is often used. In this case, the
methyl end of the FA is termed the omega carbon (ω); therefore,
9,12-octadecadienoic acid (18:2) becomes 18:2ω-6 since the
first double bond is six carbons from theωcarbon. Table 1.12
shows some common FAs, their lengths, and double bond char-
acteristics. When discussing FAs, the term double bond simply
indicates the lack of hydrogen across a hydrocarbon bond:

CH CH (double bond; unsaturated)
vs. CH2 CH2 (saturated)

Figure 1.5.The structures ofcis- andtrans-oleic acid.

Geometrically, double bonds can be eithercisortrans, with
the cis configuration being the naturally occurring form, bulky
and susceptible to oxidation. The trans configuration is more
linear, has properties similar to a saturated FA and is not found
in nature (see Figure 1.5).

Triglycerides and Phospholipids

In foods, most lipids exist as triglycerides (TGs), making up 98%
of food lipids. The name triglyceride refers to its biochemical
structure consisting of a glycerol having three FAs bound at its
hydroxyl groups. TGs are the primary energy storage form in
animals, seeds and certain fruits (e.g. avocado and olive). In
comparision to carbohydrates, TGs provide more than double
the energy, on a dry basis (9 kcal/g vs. 4 kcal/g). Food TGs also
provide mouthfeel and satiety as well as aid in the provision
and absorption of fat-soluble vitamins (i.e. A, D, E and K). In
terms of food structure, TGs play critical roles in the structures
of emulsified food products (oil and water mixtures) like ice
cream and chocolate. In ice cream, liquid fat globules partially

Table 1.12.Selected Common Fatty Acids

Fatty Acid Systematic Name

Number of
Carbons Abbreviation

Butyric Butanoic 4 4:0
Lauric Dodecanoic 12 12:0
Myristic Tetradecanoic 14 14:0
Palmitic Hexadecanoic 16 16:0
Stearic Octadecanoic 18 18:0
Oleic 9-octadecenoic 18 18:1 (n-9)
Linoleic 9,12-octadecadienoic 18 18:2 (n-6)
Linolenic 9,12,15-octadecatrienoic 18 18:3 (n-3)
Arachidonic 5,8,11,15-eicosatetraenoic 20 20:4 (n-6)
EPA 5,8,11,14,17-eicosapentaenoic 20 20:5 (n-3)
DHA 4,7,10,13,16,19-docosahexaenoic 22 22:6 (n-6)
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