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The Effects Of Different Processing Techniques On The Organoleptic Quality Of Soy Milk
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At recent study
reports trypsin inhibitor activity commercial protein isolate but no
inhibitor was detected in canned frankfurters containing 1.5% isolate.
The heat treatment during canning inactivated the residual inhibitor.
Many
of the conclusion drawn from studies on kunity inhibitor must be viewed
with some reservations because of the heterogeneity of certain
commercial preparation even when crystallized five times. The
possibility that a protein impurities or a tightly bound non-protein
impurity is responsible for some of the biological properties of the
inhibitor has received slight consideration until recently.
Hemagglatinins
–Soybean contain at least four proteins capable of causing clumping of
red blood cells of rabbits and rates in invitrotests. These proteins are
designated haemagluttinins; these proteins are in many legumes.
Defected soy flour contains about 3% lemaglutinins. The major
hemagluttinin in soybeans has been insolated and characterized. It is a
glycoprotein containing 4.5% mannose and 1% glucesanine and has a
molecular weight of 110,00 and appear to contain two polypeptide chains.
The ability of hemaggluttinins to cause clumping of red blood cells in a
test tube serves as a useful assay procedure but there is no evidence
that agglutination of red cells occurs when hemagluttinins are ingested.
Hemagglutinins is readily inactivated by pepsin; thus it probably does
not service passage through the stomach. Furthermore, undigested
hemagglutinin would have to be absorbed from the intestine to come into
contact with red blood cells an occurrence which seems unliky because of
the high molecular weight of
the hemagglutinin.
Soybean
hemagglutinins are readily inactivated when maximum growth response is
obtain. Hemagglutininsthis ;present no known problems in foods of
preparation includes proper heating of the soy ingredient at some step
of processing.
Soybean saponings – saponins are complex glycosides of
triterpenoid alcohols and occur in soybeans to the extent of 0.5% and
because of their polarity, the saponins are insoluble in hexane and
remain in defatted meal; defatted meal contains 0.6^ saponins. Although
antinutritional properties have been ascribed to soybean saponins,
recent studies show t hem to be harmless when ingested by chicks rates
and nice aft 0.5 to 3% of the diet. At the highest level the saponins
content was about three fold higher than in a 50% soybean meal
supplemented diet. Neither saponings nor sapogenine were found in blood
of rates, mice or chicks kept in diet containing 20% soybean seed, thus
the saponins are not absorbed thy remain intact until they leave the
enzymes in the colon. The saponin inhibit various enzymes including
cholinesterase and chymotrypsin but inhibition is not specific.
Soyprotein and other dietary protein will also bind saponins.
Approximately 0.4% saponins were obtained from a laboratory preparation
of soy
protein isolate when isolates where ehated in dilate and
solutions crystalline bit apparently modified. Saponins were obtained.
The effect of interaction of the saponins with soy protein is still
unknown, the saponins are an extremely complex mixture and only limited
separations have been obtained to date.
Protein quality of soybean.
Until
the 1960’s information on the nutritive value of soybean protein was
largely limited to defatted flakes, meals and flours. Moreover most of
the studied were concerned with use of soybean means as an animals feed.
Since commercial introduction of concentrates and isolates in 1959 and
their increasing use in foods, these fractions have received
considerably more attention studies with human, however, are still
limited. The quality of soy protein depends on several factors:-
a) Amino acids composition
b) Presence of anti-nutritional factors
c) Digestibility
d) Overall composition of the diet
e)
Nutrient requirement of the species involves. Item a, b, and c are of
primary importance in considering the various soy protein forms as
protein sources.
In the preparation of isolates for example
fractionation occurs; this results in a change in amino acid composition
as well as in removal of the antinutritional factors occurring in the
whey, items of and e are of greater importance when a specific food is
being considered i.e. an infant food dietary item or a soack food
nutritional requirements for an infant differ greatly from the needs of
an adult who may be trying too loose weight.
1.6 AIMS AND OBJECTIVES OF THE PROJECT
The
processing of soybeans into soymilk is aimed at gaining consumer
acceptance of the legume by removal of the toxicants that contain and
also improving organoleptic qualities of soymilk with special
consideration to some adverse effect of these operation in soymilk
quality.
This project re views the effects of different methods used
in the processing of soybeans into soymilk on the quality of the milk
produced during processing and storage.
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