Biomedical Engineering Reference
In-Depth Information
salts. Examples of food sols include some liquid chocolates, instant drinks, some
frosting mixes, and pigmented foods.
Foaming and Defoaming Activity
Upgraded lecithins have been employed as effective foam control agents in whipped
toppings, ice creams, and many types of candies. They have also been used as
effective defoaming agents in foams caused by powdered proteins in water. This is
an excellent example of the system specificity of lecithin products.
50
Lecithin is used
in a large variety of food products such as margarine, confections, snack-food, soups,
baked goods, cheese products, processed meat, poultry and fish products, dairy and
dairy-type products, and dairy supplements. Commercial soybean lecithin products
have been used in many food applications which are not directly related to their
emulsification activities. Some of these include: (1) co-emulsification for monoglyc-
erides to interact with amylose, (2) deoiled soy lecithin, 95% powder, as co-dispers-
ant, (3) spray-dried combination of standard soy lecithin and milk solids (mainly
lactose) as a dispersant and wetting agent, (4) spray-dried combination of modified
partial glycerides and milk solids for flour treatment, assurance of uniformity and
high quality bread making properties with wheat flours, (5) in instant pudding mixes,
or whole-milk powders as an instantizing aid, (6) in infant formulas, to promote
remixing, (7) in egg replacers as a release agent, (8) in ice cream to increase
smoothness and prevent graininess, and (9) in meat products as a fat emulsifier.
O
THER
S
OURCES OF
L
ECITHINS
Cottonseed Lecithins
Only limited quantities of cottonseed lecithins are available.
48,56,57
Most of the phos-
pholipids are present in the non-oil materials (1 to 2%) separated from hydraulically
pressed oil by alkali or water washing. Different extraction methods normally used
in the oil crushing industry cause few differences in the percentage of phospholipids
or fatty acids in cottonseed oil. However, limited data are available in the literature
on the composition of all cottonseed phospholipids and all of the lecithin and
cephalin components have not been individually separated and quantified. The pub-
lished literature contains a diversity of standard research procedures for isolating
the total phospholipid portion of plant materials.
54-58
They include solvent extraction
of the lipids and application of various separation and purification steps for frac-
tionation and quantifying the individual phospholipids. Additionally, these proce-
dures include steps to concentrate the crude phospholipid extracts, to remove non-
phospholipid impurities, and selectively precipitate or extract the phospholipids.
These methods use solvent, solvent-solvent counter current fractionation, metal salt
complexing and precipitation, column chromatography, and fractional crystallization
procedures. Cottonseed lecithin contains phosphatidylcholine (23.2% of total phos-
phorus), phosphatidyl-ethanolamine (13.5%), phosphatidylinositiol (13.4%), phos-
phatidylserine (2.4%), and phosphatidic acid (8.8%). Since cottonseed oil and lec-
ithin contain only trace amounts of fatty acids with more than two double bonds
(linoleic acid), oxidative rancidity is less of a problem. Other sources of phospholipids
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