112 • Impacts of Applied Genetics— Micro-Organisms, Piants, and Animals 
dustry, particularly for starch processing. En- 
zymes began to be used in quantity only 20 
years ago. In the early 1960’s, glucoamylase en- 
zyme treatment began to replace traditional 
acid treatment in processing starch; around 
1965, a stable protease (an enzyme) was in- 
troduced into detergent preparations to help 
break down certain stains; and in the 1970’s, 
glucose isomerase was used to convert glucose 
to fructose, practically creating the high-fruc- 
tose corn syrup industry. 
Genetic engineering and enzymes in 
the food processing industry 
Biotechnology applied to fermentation proc- 
esses will make available larger quantities of ex- 
isting enzymes as well as new ones. (See ch. 5.) 
The role of genetic engineering in opening com- 
mercial possibilities in the food processing in- 
dustry is illustrated by the enzyme, pullulanase. 
This enzyme degrades pullulan, a polysaccha- 
ride, to the maltose or high-maltose syrups that 
give jams and jellies improved color and bril- 
liance. They reduce off-color development pro- 
duced by heat in candies and prevent sandiness 
in ice cream by inhibiting sugar crystallization. 
Maltose has several unique and favorable char- 
acteristics. It is the least water-absorbent of the 
maltose sugars and, although it is not as sweet 
as glucose, it has a more acceptable taste. It is 
also fermentable, nonviscous, and easily solu- 
ble. It does not readily crystallize and gives de- 
sirable browning reactions. 
Pullulanase can also break down another car- 
bohydrate, amylopectin, to produce high amy- 
lose starches. These starches are used in indus- 
try as quick-setting, structurally stable gels, as 
binders for strong transparent films, and as 
coatings. Their acetate derivatives are added to 
textile finishes, sizing, adhesives, and binders. 
In food, amylose starches thicken and give tex- 
ture to gumdrop candies and sauces, reduce fat 
and grease in fried foods, and stabilize the pro- 
tein, nutrients, colors, and flavors in reconsti- 
tuted products like meat analogs. 
In view of the current shortages of petro- 
leum-derived plastics and the need for a biode- 
gradable replacement, amylose’s ability to form 
plastic-like wraps may prox ide its largest indus- 
trial market, although that market has not yet 
been dex eloped. 
If applications for the products made l)v 
pullulanase can be dex eloped, genetic engineei'- 
ing can he used to insert this enzyme into in- 
dustrially useful organisms and to increase its 
production. Howexer, the food processing in- 
dustry is permitted to use only enzymes that are 
obtained from sources approxed for food use. 
Since the chief source of pullulanase is a patho- 
genic bacterium, Klebsiella aerogenes, no signifi- 
cant efforts hax e been made to apply genetics to 
improve its production or (lualitv. Molecular 
genetics could ultimately transfer the pullula- 
nase trait from K. aerogenes to a micro-organism 
approved for food use, if a])prox ed micro-oi'ga- 
nisms that manufacture pullulanase cannot he 
found. 
Sweeteners, flavors, and fragrances 
Biotechnology has already had a markc'd im- 
pact on the sxveetener industry. I he ax ailabilitx 
of the enzymes glucose isonu'rase, inxcrta.se, 
and amylase has made the production of high- 
fructose corn sweetenei's (III'(’S) pi'ofitahle. Pro- 
duction of HFCS in the Unitcul Stat('s has in- 
creased from x'irtually nothing in 1970 to 10 
percent of the entire productit)n ol ('alori(' 
sxveeteners in 1980 (11 Ih p('r capita). TIk* price 
advantage of HFCS is expcctc'd to cause its con- 
tinued groxvth, particularly in the hcx('ragc in- 
dustry. In fact, the (^oca (’ola ( o. announced in 
1980 that fructose will .soon constitute as much 
as 50 percent of the sxvecteiK'i’ u.sc'd in its name 
brand bex erage. 
Biotechnology can b(? us(’d to product* other 
sxveeteners as well. While it is unlikt'lx that su- 
crose xvill ever be mad(? In micro-organisms (al- 
though impi’oxements in sugarcane and sugar 
beet yields may result fi'om agricultural genetic 
studies, see ch. 8 ), th(* microbial production ol 
loxv-caloric sxxeeteiKM's is a distinct possibility 
Three nexv ex|)erimental sxx (’cteners— as|)ai - 
tame, monellin, and thaumatin— arc candidates 
Aspartame is synthesized cln'micallx Irnm 
the amino acids, aspartic acid and phcnxiala- 
nine, which can thtMii.selx vs he madt* In Icnncn- 
