Food Chemistry

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Food Chemistry
Lipid
Present By: GM. Rabiul Islam
Assistant Professor
Department of Food Engineering and Tea Technology
Shahjalal University of Science and Technology, Sylhet
Lipid
• Lipids constitute a broad group of naturally
i l l hi hoccurring molecules which
include fats, waxes, sterols, fat‐
soluble vitamins (such as vitamins A, D, E and
K), monoglycerides, diglycerides, phospholipid
s, and others. The main biological functions of
lipids include energy storage, as structural
components of cell membranes, and as
important signaling molecule

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lipid
esters
Glycerol
Fatty acid

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Fatty acid
Linolic acid
Linolinic acid
Conjugated fatty acids and
Conjugated linoleic acids (CLA)
Conjugated fatty acids are polyunsaturated fatty acids in which at least one pair
of double bonds are separated by only one single bond, as in conjugated linoleicof double bonds are separated by only one single bond, as in conjugated linoleic
acid
C j t d li l i id (CLA) f il f t l t 28[1] i f li l iConjugated linoleic acids (CLA) are a family of at least 28[1] isomers of linoleic
acid found mainly in the meat and dairy products derived from ruminants. As the
name implies, the double bonds of CLAs are conjugated, with only one single bond
between them.

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Phospholipids
• Phospholipids are a class of lipids and are a
j t f ll ll bmajor component of all cell membranes as
they can form lipid bilayers.
Phospholipids (Amphipathic character)

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lipid
lipid
Distribution of fatty acid in animal and vegetable fat

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Modification of lipid
• Fractionation: The high melting ( stearine)
d th l lti ( l i ) f tiand the low melting ( oleic) fraction are
separated by fractionated crystllinzation
• Hydration: Saturation by H2 addition (catalysts
Ni)
• Interesterification: Interesterified fat is a typeInteresterification: Interesterified fat is a type
of oil where the fatty acids have been moved
from one triglyceride molecule to another
Physical characteristics of Fat
General character:
• Melting point or melting range
• Titer solidifying point after saponification
• Cloud pint: Temperature at which
crystallization starts

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Crystallization of fat
‐Nucleous formation
Crystall growth
Poly morphism of fat
The occurrence of several different crystal forms
f dfor a same compound.

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Double Chain Length Structures of Triglycerides
D
D
D
Alpha Beta-Prime Beta
(Vertical tuning fork) (Tilted tuning fork) (Stacked chair)
Characteristic of polymorphic form of
try glycerol

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Melting process of solid fat
SFC curve for determining solid fat

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Mesomorphi phases
Between liquid and solidBetween liquid and solid
Vender walls interaction