Food Biochemistry and Food Processing (2 edition)

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)