Food Biochemistry and Food Processing (2 edition)

BLBS102-c09 BLBS102-Simpson March 21, 2012 11:15 Trim: 276mm X 219mm Printer Name: Yet to Come

198 Part 2: Biotechnology and Enzymology

Table 9.2.(Continued)

Group(s) of Enzyme Used

Food Products in Transformations Nature of Transformation(s) Induced

Candies and

confectioneries

 Amylases and invertases

 Amylase, invertase and

protease mix


 Lipases

 To produce high-maltose and high-glucose syrups for the manu-

facture of hard candies, soft drinks, and caramels; and to increase

sweetness and aid soft cream candy manufacture; and for the recov-

ery of sugars from candy scraps


 To improve sweetness, texture, and stability of candied fruits

 To modify butterfat to increase buttery flavors and reduce sweetness

in candies and caramels

Animal feed and pet

care

 Cellulases and pectinases


 Alkaline proteases


 Carbohydrase, phytase,

and protease mix


 Proteases

 To facilitate silage production


 To decolorize whole blood from abattoirs for use as animal feed


 To increase metabolizable energy and protein utilization, reduce

viscosity, and liberate bound phosphorous


 To reduce pain and inflammation and increase wound healing

milk and dairy products for the benefit of individuals that

are lactose-intolerant. Catalase fromA. nigeris used to de-

compose residual H 2 O 2 (that is used in some countries as a

preservative for milk and whey; Burgess and Shaw 1983) into

H 2 O and O 2 that are nontoxic unlike H 2 O 2.

Meat and Fish Products

Meat Tenderization

Tenderness in meats relates to the ease of these products to

chomping or chewing. Meat tenderness arises from modifica-

tions in muscle proteins and entails breakdown of connective

tissue proteins by proteases. These hydrolytic enzymes may be

naturally present in the post-mortem animal (e.g., cathepsins)

or they may be added exogenously. In some meats, the action of

the endogenous enzymes may be inadequate to achieve tender-

ization within a time period that is useful. Exogenous enzymes

that are used for household or commercial purposes include

thermostable proteases from microbial and plant sources. Some

peculiar features of these proteases used as meat tenderizers

include their broader specificity and thermostability. Examples

are papain, ficin, and bromelain (all from plant sources). The

enzymes may be applied by sprinkling over the animal surface

or dipping chunks of the meat in a protease solution (mostly in

household practices). The disadvantage with these approaches

is that the enzymes get unevenly distributed in the meat and

results in unequal tenderness in different parts of the meat (e.g.,

the interior of the meat may invariably be tougher than the

outside). Commercial practices include spreading the enzyme

throughout the meat either by repeated pre-mortem injections

of the protease solutions into the animal prior to slaughter or via

post-mortem injections spread over several parts of the carcass.

Fish Processing

Enzymes are used in the fishing industry to achieve a variety of

results such as their use in de-skinning fish species that are nor-

mally difficult to de-skin by manual or mechanical operations

(e.g., squid, skate, and tuna). De-skinning is achieved using a

mixture of proteolytic and glycolytic enzymes (Haard and Simp-

son 1994, Gildberg et al. 2000, Shahidi and Janak Kamil 2001).

Heat-stable fungal and plant proteases are also used to accelerate

fish sauce fermentation (Raksakulthai and Haard 1992a,1992b,

Haard and Simpson 1994), and proteases are also used to en-

hance flavor development during the preparation of fermented

herring (Matjes; Simpson and Haard 1984) and to tenderize

squid meat (Raksakulthai and Haard 1992a,1992b).

Enzymes in Beverages

A number of enzymes are used in the manufacture of alcoholic

and nonalcoholic beverages. Enzymes such as heat-stable bac-

terial amylases, glucanases, and pullanases are used to liquefy

starches from cereals during mashing to increase fermentable

sugar levels in the wort; heat-stable bacterial phytases are used

to break down insoluble phytins into phytic acid, which is more

soluble and lowers the pH for improved microbial and enzymatic

activity in the fermentation medium; and various proteases are

used to digest large-molecular weight and water-insoluble pro-

teins (e.g., albumins and globulins) into smaller and soluble

peptides in order to curtail haze formation in the products.

The nonalcoholic beverages include juices derived from

various fruits (citrus, apples, apricots; and tropical fruits such

as avocadoes, bananas, mangoes, and papayas) and vegetables

(e.g., carrots), as well as tea, cocoa, and coffee. The enzymes

that are used to facilitate the processing of fruits and vegetables

into juices include a range of pectinases for peeling the

fruits, maceration, removal of pectins, viscosity reduction, and

clarification of the juice); amylases and AMGs are applied for

breaking down starches in high starch-containing fruits (e.g.,

unripe apples, bananas) to prevent post-product haze develop-

ment in the products; cellulases and hemicellulases are used for

digesting cellulose and fruit cell wall hemicellulosic materials

(i.e., polysaccharides made up of a number of different