Chemistry Project

Study of Comparison on Soya

Milk (Soymilk) and Natural Milk

Submitted To:

Submitted BY:

Rohit

Kumar

Soy milk

Soy milk (also called soya milk, soymilk, soybean milk, or soy juice) and

sometimes referred to as soy drink/beverage is a beverage made from

soybeans. A stable emulsion of oil, water, and protein, it is produced by

soaking dry soybeans and grinding them with water. Soy milk contains

about the same proportion of protein as cow's milk: around 3.5%; also 2%

fat, 2.9% carbohydrate, and 0.5% ash. Soy milk can be made at home with

traditional kitchen tools or with a soy milk machine.

The coagulated protein from soy milk can be made into Tofu, just as dairy

milk can be made into cheese.

Nutrition and health information

Nutrients in 8 ounces (250ml) of plain soymilk:

Regular Soymilk Lite Soymilk (reduced fat)

Calories (gm) 140 100

Protein (gm) 10.0 4.0

Fat (gm) 4.0 2.0

Carbohydrate (gm) 14.0 16.0

Sodium (mg) 120.0 100.0

Iron (mg) 1.8 0.6

Riboflavin (mg) 0.1 11.0

Calcium (mg) 80.0 80.0

Preparation

Soy milk can be made from whole soybeans or full-fat soy flour. The dry

beans are soaked in water overnight or for a minimum of 3 hours or more

depending on the temperature of the water. The rehydrated beans then

undergo wet grinding with enough added water to give the desired solids

content to the final product. The ratio of water to beans on a weight basis

should be about 10:1. The resulting slurry or purée is brought to a boil in

order to improve its nutritional value by heat inactivating soybean trypsin

inhibitor, improve its flavor and to sterilize the product. Heating at or near

the boiling point is continued for a period of time, 15-20 minutes, followed

by the removal of an insoluble residue (soy pulp fiber or okara) by filtration.

There is a simple yet profound difference between traditional Chinese and

Japanese soy milk processing: the Chinese method boils the filtrate (soy

milk) after a cold filtration, while the Japanese method boils the slurry first,

followed by hot filtration of the slurry. The latter method results in a higher

yield of soy milk but requires the use of an anti-foaming agent or natural

defoamer during the boiling step. Bringing filtered soy milk to a boil avoids

the problem of foaming. It is generally opaque, white or off-white in color,

and approximately the same consistency as cow's milk.

For all raw soybean protein products, heat is necessary to destroy the activity

of the protease inhibitors naturally present in the soybean. The pancreas

naturally secretes proteases to digest a protein meal. Eating raw soybeans on

a regular basis causes the pancreas to hypersecrete, leading to benign tumors

of the pancreas.

When soybeans absorb water, the endogenous enzyme, Lipoxygenase

(LOX), EC 1.13.11.12 linoleate:oxidoreductase, catalyzes a reaction

between polyunsaturated fatty acids and oxygen {hydroperoxidation}. LOX

initiates the formation of free radicals, which can then attack other cell

components. Soybean seeds are the richest known sources of LOXs. It is

thought to be a defensive mechanism by the soybean against fungal

invasion.

In 1967, experiments at Cornell University and the New York State

Agricultural Experiment Station at Geneva, NY led to the discovery that

paint-like, off-flavors of traditional soy milk can be prevented from forming

by a rapid hydration grinding process of dehulled beans at temperatures

above 80 °C. The quick moist heat treatment inactivates the LOX enzyme

before it can have a significant negative effect on flavor. All modern bland

soy milks have been heat treated in this manner to destroy LOX.

Normal mature soybeans actually contain three LOX isozymes (SBL-1,

SBL-2, and SBL-3) important for undesirable flavor development. One or

more of these isozymes have recently (1998) been removed genetically from

soybeans yielding soy milk with less cooked beany aroma and flavor and

less astringency. An example of a triple LOX-free soybean is the American

soybean named "Laura".

The University of Illinois has developed a soy milk that makes use of the

entire soybean. What would normally constitute "insolubles" are ground so

small by homogenization as to be in permanent suspension.

Commercial products labeled "soy drink" are often derivatives of soy milk

containing more water or added ingredients.

Preparation of curd from soya bean milk

To 2400 kg of soy bean milk were added 71 kg of calcium hydroxide-sucrose complex

solution, 30 kg of 10% saline water and 30 kg of 5% sodium hexametaphosphate

solution. To the resulting mixture were further added 81 kg of 10% - aqueous solution of

citric acid and 170 kg of water for forcing the soy bean milk through the pipeline. The pH

value of the resulting mixture was adjusted to 7.1.

With use of the VTIS device manufactured by Alfalaval Inc., the resulting mixture was

subjected to a high temperature sterilizing treatment for 30 seconds at 140° C. by the

VTIS method, followed by cooling and further mixing with 36 kg of 10% - aqueous

solution of citric acid. The pH value of the resulting mixture was then adjusted to 5.75.

Then, with use of the aseptic charging device manufactured by Tetra Pack Co., the

mixture was conventionally charged into a container under germ-free conditions as the

opening of the container was sealed. The product thus obtained was charged into a

heating and coagulating tank and coagulated by treatment at 85° C. for 40 minutes to give

the product soy bean curd.

The resulting curd formed a highly satisfactory gel with less water oozing and with a

mild creamy texture. The calcium contents in the product amounted to 100 mg % as

calcium so that the curd provided to be an excellent calcium-enriched foodstuff.

It is noted that the soy bean milk used in the present Example is composed of 12.0

percent of total solid contents, 5.8 percent of protein and 30 mg % as calcium, and the

solution of the calcium hydroxide-sucrose complex is a solution in 43.0 ky of water of

5.0 kg of calcium hydroxide and 23.3 kg of succrose.

Soya Curd

Soya Curd, (Soya yoghurt in British English) also referred to as is curd

prepared using soy milk, Curd bacteria, mainly Lactobacillus bulgaricus and

Streptococcus thermophilus and sometimes additional sweetener, like

fructose, glucose, or raw sugar . It is suitable for vegans, as the bacteria for

shop-bought Soya Curd are usually not grown on a dairy base.

Soya Curd can be prepared at home using the same method as dairy Curd .

One tablespoon of sugar per 1 liter of unsweetened soy milk may be added

to promote bacterial fermentation. Soy milk on its own lacks the lactose

(milk sugar) that is the basic food for the Curd bacteria.

Soya Curd may have a slight beany soy taste when made directly from

freshly prepared soymilk, but this is less pronounced in shop-bought Soya

Curd and in Soya Curd made from commercial soy milk.

Soya Curd contains less fat than Curd made with whole milk. This amounts

to about 2.7% (the same percentage as soy milk), versus 3.5% in dairy Curd.

However, dairy Curd can be made with 2%, 1%, or fat-free milk, and these

cases; it is lower in fat than Soya Curd.

Buffalo curd(Natural milk Curd)

A pot of water buffalo curd with coconut honey.

Buffalo curd (in Hindi - "Dahi") is a traditional and nutritious dairy product

prepared by buffalo milk and it is popular throughout the south Asian

countries such as India, Sri Lanka, Nepal, etc. Buffalo milk is traditionally

better than cow milk for curd due to its higher fat content making a thicker

curd. Mostly clay pots are used as packaging material for Buffalo curd.

Buffalo curds is obtained by curdling (coagulating) buffalo milk using

microbial activities. In this process lactose in buffalo milk is converted in to

lactic acid using several micro-organisms. Several micro-organism species

are involved in the fermentation such as Streptococcus lactis, Streptococcus

diacetylactis, Streptococcus cremoris, Lactobacillus bulgaricusand and

Streptococcus thermophillus.

Buffalo curd has a higher nutritional value of protein, fat, lactose, minerals

and vitamins. It should have 7.5% of milk fat, 8.5% of milk solids and 4.5%

of Milk acid (lactic acid). Quality of the curd is totally depend on the starter

culture. Fermentation also develops the characteristic flavor and colour of

the product.

Buffalo curd can be made in both traditional and industrial forms.

Traditionally buffalo milk is filtered and boiled, the scum is removed and it

is cooled to room temperature. A few spoonfuls of a previous batch of curd

are added and it is then mixed well and poured into clay pots. These are

sealed by wrapping a piece of paper over the pot and allowing it to stand for

12 hours.

EXPERIMENT

Preparation of soyabean milk and its comparison with

the natural milk with respect to curd formation, effect

of temperature and taste.

REQUIREMENTS

Beakers, pestle and mortar, measuring cylinder, glass

rod, tripod-stand, thermometer, muslin cloth, burner.

Soyabeans, buffalo milk, fresh curd and distilled

water.

PROCEDURE

1) Soak about 150g of Soya beans in sufficient amount of water so

that they are completely dipped in it.

2) Take out swollen Soyabeans and grind them to a very fine paste

3) Take out swollen Soyabeans and grind them to a very fine paste

and filter it through a muslin cloth. Clear white filtrate is

soyabean milk. Compare its taste with buffalo milk.

4) Take 50 ml of soyabean milk in three other beakers and heat the

beakers to 30°, 40°and 50°C respectively. Add ¼ spoonful curd

to each of these beakers. Leave the beakers undisturbed for 8

hours and curd is formed.

5) Similarly, take 50 ml of buffalo milk in three beakers and heat the

beakers to 30°, 40° and 50°C respectively. Add ¼ spoonful

curd to each of these beakers. Leave the beakers

undisturbed for 8 hours and curd is formed.

RESULT:

1. Natural milk is sweet in taste while soya bean milk is not.

2. The curd formation is take place at a faster rate with increase and both type of

milk.

3. In natural milk, fermantation take place faster at a higher temperature, leading to

formation of larger amount lactic Acid which imparts of sour taste.