1. A PROJECT REPORT ON-
Submitted to:
Mrs. MADHU KAGAT
(Subject teacher : Food
and nutrition, Bio
chemistry)
Submitted by:
HARSHITA
BHARGAVA
(B.sc. Home sci.
II yr)
2. Lipids are ester of Fatty acids
and Glycerol.
• They are also naturally occurrence product
/substance .
• They form a group of organic compound which
are widely distributed in living system.
• They are formed by carbon, hydrogen and
oxygen.
• They are also known as fats.
• Chemical name of fats is TRIGLYCERIDE
• Which have 1 part of glycerol and 3 part of
fatty acid.
CHEMICAL FORMULA
OF LIPIDS.
CH3 –CH2-CHn-COOH
5. The major sources come from soybean,
palm, rapeseed/canola, sunflower seed,
coconut and others.
Soybean Oil
The major fatty acids in soybean oil are linoleic (53
%), oleic (23 %), palmitic (11 %), linolenic (8 %) and
stearic (4 %) (Wang, 2002).
A healthy oil, low in saturated acids and rich in
polyunsaturated fatty acids (PUFA), especially
linoleic acid.
Soybean oil in its native but refined form or in some
partially hydrogenated form is widely used for food
purposes such as frying and salad oils, margarine
and shortening, and mayonnaise and salad
dressing.
6.
Palm Oil
The oil palm produces two different oils – palm
kernel oil and palm oil.
Malaysia and Indonesia are the major producing
and exporting countries of palm oil.
Palm oil is considered as a saturated fat in
comparison to the more highly unsaturated
vegetable oils.
The oil is rich in nutritionally important minor
components.
Because of its fatty acid composition and its minor
components which act as antioxidants, palm oil has
high oxidative stability.
Palm oil is used for a wide range of food purposes
including frying, in spreads and in shortenings.
Palm olein is a major frying oil, and palm stearin
finds increasing use as hard stock in fat blends
which are interesterified to produce spreads with no
hydrogenated oil and therefore containing little or no
trans acids.
7. Rapeseed/Canola Oil
Rapeseed and canola are terms describing the seed
and extracted oil from Brassica species including B.
napus (formerly B. campestris), B. rapa and
B.juncea.
The seed oil from these species was typically rich in
erucic acid (22:1), and the seed meal had an
undesirably high level of glucosinolates.
Typically it contains palmitic (4 %), stearic (2 %),
oleic (62 %), linoleic (22 %) and linolenic (10 %)
acids and has less saturated acids than any other
commodity oil.
With its low level of saturated acids, its high level of
oleic acid and the presence of linoleic and linolenic
acids at a favourable ratio (~ 2:1) rapeseed oil rates
highly in the classification of healthy oils.
The oil is used as a salad oil and salad dressing and
mayonnaise, in margarine and other spreads, as a
frying oil, and in many minor food applications.
8. Sunflower Seed Oil
Oil obtained from sunflower seeds (Helianthus
annuus)
Sunflower oil is available in three ranges of fatty acid
composition. The traditional and still major sunflower
oil is linoleic-rich, but two other forms have been
produced by conventional seed breeding; these are
a high oleic oil and a mid-oleic oil.
Crude sunflower oil contains phospholipids (0.7–0.9
%), tocopherols (630–700 ppm), sterols (~ 0.3 %)
and carotenoids (1.1–1.6 ppm).
The seeds are also a rich source of selenium
compared to most other seeds and nuts.
Sunflower seed oil contains some wax (esters of
longchain alcohols and long-chain acids) coming
from an outer protective seed coat, which makes the
oil appear cloudy.
The oil is to be used as a salad oil.
9. Lauric
oils (coconut, palmkernel)
Coconut oil and palmkernel oil are similar to one
another in their fatty acid composition.
Both have high levels of medium-chain saturated
acids, especially lauric acid (12:0), hence the term
lauric oils.
They have only low levels of unsaturated C18 acids
and low iodine values.
They are used extensively both as food and as
nonfood
oils and serve as the major source of C8
(caprylic or octanoic) acid and C10 (capric or
decanoic) acid.
10. There are two major sources of land animal derived
lipids used for human nutrition: the lipids in animal
body tissues, commonly referred to as animal fats or
meat fats, and the milk lipids.
The technical term ‘animal fats’ or ‘meat fats’
actually refers to fat obtained from adipose tissues
of land animals by a process called rendering.
Fat is typically deposited in the abdominal
cavity, particularly around the kidneys and
the stomach (internal fat), peripheral under
the skin (subcutaneous adipose tissue),
between muscles and between muscles and
bones (intermuscular fat) and within skeletal
muscles (intramuscular fat).
11. Classification of lipids according to nutritional value in foods:
Lipids
Simple
Compound
Types of classification:
Simple
Compound
Derived/Sterols
•Fats and oil
•Wax
•Sulpholipids
•Glycolipids
•phospholipis
•liprotein
Derived/Sterols
24. Physical
Properties of Oils & Fats
Thermal properties:
crystallization & melting
the formation of solid and liquid
the behavior of plastic fats that are mixtures of
solid and
liquid components
Mandatory, example:
salad oils do not contain lipids that will crystallize
during
storage in a refrigerator.
Most frying oils and oils used as food coatings (and
lubricants) should also be free of solid components
25. Physical
Properties of Oils & Fats
Spreads:
depends on having appropriate levels of solid fat at
refrigerator temperature, at ambient temperature
and
at mouth temperature.
The solid fat content at 4 °C should not exceed 30–
40
% (to be spreadable from the refrigerator); at 10 °C
it
should be 10–20 % (the fat will ‘stand up’ --- not
collapse to a puddle of oil).
26. Chemical
Properties of Oils & Fats
Food lipids are not usually considered to require
defined chemical properties, but without
oxidative stability of their lipid components foods
would quickly become rancid and have a short
shelf life.
For this reason they should be oxidatively stable.
This can be determined by the peroxide value of
fats/oils. This indicates the degree of oxidation
that has been taken place in a fat/ oil.
Saponification value indicates the average
molecular weight of fatty acid in a fat.
27. Chemical
Properties of Oils & Fats
Iodine value – express the degree of
unsaturation of the FAs in the fat (the amount of
iodine absorbed by a fat/100 g basis). The
higher iodine value indicates the greater the
degree of unsaturation.
Hydrolytic rancidity refers to the rancidity that
occurs under conditions of moisture, high
temperature, and natural lipolytic enzymes. The
acid value represents free fatty acids in fat that
were released during hydrolysis.
28. HYDROLYSIS
Hydrolysis is the process where in a covalent bond within a molecule
is broken down. A water molecule is used up in the process
(hydro=water ; lysis=cut/sever) Usually the process results in one
of the reaction products having a Hydrogen atom where the bond
used to be, and the other having a hydroxyl group (-OH, also
known as an alcohol)
In the case of lipids, the molecule itself consists of a glycerol
backbone bonded to three long chain fatty acids. Hydrolysis of the
lipid results in breaking the fatty acids off, leaving free fatty acids
and a glycerol molecule, and using up three water molecules.
This process can be catalyzed under acidic or basic conditions, and
is actually how soap is made. Reacting the free fatty acids with
some ionic salts actually gives you soap. The left over glycerol is
more commonly known as glycerin, which is itself found in a great
many products.
29. Types
Usually
hydrolysis is a chemical process in which a
molecule of water is added to a substance.
Sometimes this addition causes both substance and
water molecule to split into two parts. In such
reactions, one fragment of the target molecule (or
parent molecule) gains a hydrogen ion.
Esters and amides
Perhaps the oldest commercially practiced example
of ester hydrolysis is saponification (formation of
soap). It is the hydrolysis of a triglyceride (fat)
with an aqueous base such as sodium
hydroxide (NaOH). During the process, glycerolis
formed, and the fatty acids react with the
base, converting them to salts. These salts are
called soaps, commonly used in households
30.
31.
32. SAPONIFICATION
Saponification is a process that produces soap,
usually from fats and lye. In technical terms,
saponification involves base (usually caustic
soda NaOH) hydrolysis of triglycerides, which
are esters of fatty acids, to form the sodium salt of
a carboxylate . In addition to soap, such traditional
saponification processes produce glycerol.
"Saponifiable substances" are those that can be
converted into soap.
. Saponification is the alkaline hydrolysis of the fatty
acid esters.
33. .
In the industrial manufacture of soap, tallow (fat from animals such as cattle
and sheep) or vegetable fat is heated with sodium hydroxide. Once the
saponification reaction is complete, sodium chloride is added to precipitate the
soap. The water layer is drawn off the top of the mixture and the glycerol is
recovered using vacuum distillation
34.
One of the organic chemical reactions known to ancient man was the
preparation of soaps through a reaction called saponification. Natural
soaps are sodium or potassium salts of fatty acids, originally made by
boiling lard or other animal fat together with lye or potash (potassium
hydroxide). Hydrolysis of the fats and oils occurs, yielding glycerol and
crude soap.
Vegetable oils and animal fats are the main materials that are saponified.
These greasy materials, triesters called triglycerides, are mixtures derived
from diverse fatty acids. Triglycerides can be converted to soap in either a
one- or a two-step process. In the traditional one-step process, the
triglyceride is treated with a strong base (e.g., lye), which accelerates
cleavage of the ester bond and releases the fatty acid salt and glycerol.
This process is the main industrial method for producing glycerol. If
necessary, soaps may be precipitated by salting it
out with saturated sodium chloride.
The saponification value is the amount of base required to saponify a fat
sample. For soap making, the triglycerides are highly purified, but
saponification includes other base hydrolysis of unpurified triglycerides,
for example, the conversion of the fat of a corpse into adipocere , often
called "grave wax." This process is more common where the amount
of fatty tissue is high, the agents of decomposition are absent or only
minutely present. Cheese
35.
36. Fats
and oils are esters made from glycerol
propanetriol) and long chain fatty acids such as
stearic acid (
). Different acids
combined with glycerol produce different fats and
oils
Glycerol is an alkanol with 3 hydroxy groups and
the formula CH2OHCHOHCH2OH. Its systematic
name is 1,2,3-propanetriol.
During saponification glycerol present in fats and
oil act as acid which react with base and separetes
after the reaction as a bi-product.
39. Saponification Explained
In simple terms, saponification is the name for a chemical reaction between an
acid and a base to form a salt. While making soap using the cold process, mix an
oil or fat (which is acid) with Lye (which is base) to form soap (which is a salt).
The base must always be composed of one hydroxide ion. For the most part, people
use lye (one sodium ion and one hydroxide ion) as their base. Notice that the
sodium ion does not take part in the reaction at all. For this reason, other bases
like potassium hydroxide can be used as well because it too is made up of one
hydroxide ion. Potassium hydroxide is more prominently used for liquid soap
making.
There are many different types of acids that will react with base and saponify.Acid
could be olive oil, coconut oil or tallow among others. Each acid has a unique
combination of triglycerides (compounds made of three fatty acids, attached to a
single molecule of glycerol) which combines with the base (lye) differently. The
amount of base needed to react with the acid will vary depending on the chemical
makeup of the acid..
Combine , and stir the carefully measured acid and base together, they start to
react. The triglycerides within the acid release the single glycerol molecule (which
turns into skin nourishing glycerin) allowing the fatty acids to combine with the
hydroxide ions within the base, forming soap.
Two reactions occur. The first reaction is glycerol turning into beneficial glycerin,
and the second reaction is the acid and the base combining to form a salt which is
soap.
40. Unsaturated fatty acids may be converted to saturated fatty acids by the
relatively simple hydrogenation reaction. The addition of hydrogen to
an alkene (unsaturated) results in an alkane (saturated).
A simple hydrogenation reaction is:
41. Hydrogenation – to treat with hydrogen – is a chemical reaction between
molecular hydrogen (H2) and another compound or element, usually in the
presence of a catalyst. The process is commonly employed to reduce or
saturate organic compounds. Hydrogenation typically constitutes the addition
of pairs of hydrogen atoms to a molecule, generally an alkene. Catalysts are
required for the reaction to be usable; non-catalytic hydrogenation takes
place
only at very high temperatures. Hydrogenation
reduces double and triple bonds
in hydrocarbons.
Because of the importance of hydrogen, many related reactions have been
developed for its use. Most hydrogenations use gaseous hydrogen (H2), but
some involve the alternative sources of hydrogen, not H2: these processes
are
called transfer hydrogenations. The reverse reaction, removal of hydrogen
from a molecule, is called dehydrogenation. A reaction where bonds are
broken while hydrogen is added is called hydrogenolysis, a reaction that may
occur to carbon-carbon and carbon-heteroatom
(oxygen, nitrogen or halogen)
bonds. Hydrogenation differs from protonation or hydride addition: in
hydrogenation, the products have the same charge as the reactants.
Hydrogenation of unsaturated fats produces saturated fats. In the case
of partial hydrogenation, trans fats may be generated as well.
43. Halogenation is a chemical reaction that involves the reaction of a
compound, usually an organic compound, with a halogen.
Halogenated fatty acids which are one of the most interesting groups
among the naturally occurring halogen compounds are not well known
but several reviews on these compounds may be found. Halogenated
fatty acids are found in different groups of organisms from
microorganisms to the highest plants and animals.
As halogen, they contain one or several atoms of fluor, chlorine,
or bromine.
• Fluorinated fatty acids
• Chlorinated fatty acids
• Brominated fatty acids
45. IODINE NUMBER
The iodine value (or "iodine adsorption value" or "iodine
number" or "iodine index") in chemistry is the mass
of iodine in grams that is consumed by 100 grams of
a chemical substance. Iodine numbers are often used to
determine the amount of unsaturation in fatty acids.
Full Definition of IODINE NUMBER
: a measure of the unsaturation of a substance
(as an oil or fat) expressed as the number of
grams of iodine or equivalent halogen absorbed by
100 grams of the substance <the iodine
numbers of
linseed oil, olive oil, and coconut oil are
approximately 175–201, 77–91, and 8–9.5
respectively>
46.
47. What is rancidity?
Rancidity is the development of unpleasant smells
in fats and oils, which are often accompanied by
changes in their texture and appearance.
Two types of rancidity:
Hydrolytic rancidity
Oxidative rancidity (auto-oxidation)
48. Hydrolytic rancidity
Oxidative rancidity
(auto-oxidation)
Caused by the breaking down of a lipid Occurs due to the oxidation of fatty
into its component fatty acids and acid chains, typically by the addition of
glycerol.
oxygen across the C=C bond in
unsaturated fatty acids.
C-O-CO-R + H2O → C-O-H + HO-CO-R
Occurs more rapidly in the presence of The process proceeds by a free radical
enzymes such as lipase, and with heat mechanism catalysed by light in the
and moisture.
presence of enzymes or metal ion.
The water present in the food and the The complex free radical reactions will
high temperature will increase the rate produce a wide variety of products,
of hydrolysis to fatty acids.
many of which have unpleasant odours
or tastes.
The free fatty acids have an unpleasant In highly unsaturated lipids, such as fish
smell giving a rancid smell and taste to oils, oxidative rancidity can be a major
milk and butter that have been stored problem.
for too long. Longer chain acids are less
volatile, so the smell is less noticeable.
49. Packaging
- Opaque packaging and coloured glass bottles
will reduce light induced oxidative rancidity.
- Gas impermeable wrapping film will reduce
the exposure of the product to oxygen and water
vapour in the air.
- Free space in the container should be kept to
minimum to reduce the amount of oxygen and
water vapour present. The best way is to use
vacuum packaging or fill the package with inert
gases.
-Example: Potato crisps which are usually
packed in thick foil packets filled with nitrogen.
50.
51. Acid value (or "neutralization number" or "acid number"
or "acidity") is the mass of potassium hydroxide (KOH)
in milligrams that is required to neutralize one gram
of chemical substance. The acid number is a measure of
the amount of carboxylic acid groups in a chemical
compound, such as a fatty acid, or in a mixture of
compounds.
52. The acid number is used to quantify the amount of
acid present, for example in a sample of biodiesel. It
is the quantity of base, expressed in milligrams of
potassium hydroxide, that is required to neutralize
the acidic constituents in 1 g of sample.
Veq is the volume of titrant (ml) consumed by the crude
oil sample and 1 ml of spiking solution at the equivalent
point, beq is the volume of titrant (ml) consumed by 1 ml
of spiking solution at the equivalent point, and 56.1 is
the molecular weight of KOH. WOil is the mass of the
sample in grams.
The molar concentration of titrant (N) is calculated as
such:
53. Phospholipids.
A Phospholipid molecule is like a triglyceride in
which one of the fatty acids have been replaced
by a phosphate group.
The phosphate group gives the phospholipid a
hydrophilic head and a hydrophobic tail.
Phospholipids have two ends.
A head that contains a phosphate group. This has
an uneven charge that makes the head able to
mix with water (hydrophilic).
A tail that contains 2 fatty acid chains. They have
an even charge and this makes them unable to
mix with water (hydrophobic).
54.
55.
56.
57.
58. Cholesterol is a fat-like substance with a waxy consistency that is
produced in the livers of humans and other animals. Every human cell
needs a minute amount of cholesterol in order to function properly.
While some cholesterol is essential, too much can be harmful.
Cholesterol is a lipid with a unique structure consisting of four linked
hydrocarbon rings forming the bulky steroid structure. There is a
hydrocarbon tail linked to one end of the steroid and a hydroxyl
group linked to the other end. The hydroxyl group is able to form
hydrogen bonds with nearby carbonyl oxygen of phospholipid and
sphingolipid head groups. Cholesterol is known as a "sterol" because
it is made out of a alcohol and steroid. Cholesterol is present in most
animal membranes with varying amounts but is absent in prokaryotes
and intracellular membranes.
59. Function
Cholesterol is required to build and maintain membranes; it
modulates membrane fluidity over the range of physiological
temperatures
The structure of the tetracyclic ring of cholesterol contributes to the
decreased fluidity of the cell membrane as the molecule is in a trans
conformation making all but the side chain of cholesterol rigid and
planar
cholesterol also functions in intracellular transport, cell signaling
and nerve conduction
cholesterol has also been implicated in cell signaling processes,
assisting in the formation of lipid rafts in the plasma membrane.
60.
61. Dietary sources
Major dietary sources of cholesterol
include cheese, egg
yolks, beef, pork, poultry, fish, and shrimp. Hum
an breast milk also contains significant
quantities of cholesterol.
