Summary:
The fats and oils impart flavor
and off-flavor in food. Different fats and oils have different composition by
which flavor is vary with composition. There are some factors that affect the
flavor of fats and oils such as storage conditions, temperature, oxygen, light,
air, composition of free fatty acids etc. Rancidity and oxidation is the
characteristics of off-flavors. Flavor is produced during frying of oil. Flavor
depend on oxidative stability of oil. Degree of saturation and unsaturation
tells about the composition of fatty acids that affect the flavor during
chemical reactions. Volatile compounds that are produced during frying of oil
cause off-flavor. The primary and secondary oxidation occurs in which
initiation, propagation and termination are done with the production of
volatile compounds in secondary oxidation products cause off-flavor.
Composition of fatty acids such as high level of oleic acid and low level of
linoleic and linolenic acid gives best quality oil and good flavor. The flavor
derived from fats and oils are change during chemical reaction between food
materials and oil. There are two types of rancidity, oxidative in the presence
of oxygen and hydrolytic in the presence of water and enzymes, which cause
off-flavor in fats and oils. More off-flavor occur in oxidative rancidity than
in hydrolytic. Polar compounds also affect the flavor of oil. There are less
production of volatile compounds in saturated fatty acids as compared to
unsaturated fatty acids. Flavor is affected by the exchange, absorb and
interact the lipids with food materials. There are several impacts on health of
oxidative and rancid oil. Antioxidants are add that stop autoxidation and
prevent from rancidity that gives better flavor.
Introduction:
Fats and oils impart flavor on food commodities when they are hydrolyzed or oxidize and polarize with them. Different varieties provide significant flavor after frying and storage. They become rancid or give off flavor when exposed to air and heat under undesirable conditions. The extrinsic and intrinsic factors contributes a greater role in establishing flavor to that particular product. Intrinsic are those which provides the chemical and physical characteristics whereas extrinsic are generally termed to be the storage and environmental conditions. Both factors widely effect on the flavoring compounds. Chemically it depends on the degree of saturation and unsaturation that determine the stability, melting point and firmness. Temperature and relative humidity are environmental factors that enable to make optimum storage conditions for the product.
Main body:
Generally, fats and oils are
used for frying and cooking purposes and they are oxidize and hydrolyzed due to
the presence of free fatty acids and other constituents in them. These fatty
acids when react with the oxygen, light (photo oxidation) and air produces
flavoring compounds which are nasty in odor and discolored in appearance. Some
countries such as European, African and some Asian countries desire to have the
buttery and nutty flavors in their foods
Examples are avocado oil which
makes the bland and mild flavor, coconut oil also provides the coconutty taste
when it used and it is generally 92 percent saturated fat with the stability of
oxidation so there are less chances of generating off flavor compounds and
taste, goose fat is specifically used in the roasted products as it is not
commonly available easily. Lard either it is wet or dry add up the flavor. The
dry lard gives caramelized flavor and wet lard provides neutral flavor. Peanut
oil has nutty flavor when it is in the form of unrefined state. Red palm has
the property to make the color of orange tinge but due to its compositional
benefit it is also used to make a unique flavor. The extra virgin oil delivers
the strong olive flavor, commonly used for spiciness products. Sesame oil can
add up significant flavor, they provide sharp and nutty flavor depending upon
the nature that either it is in concentrated form or diluted which is being
used in cooking several dishes. Tallow fat also used to impart flavor on
specific beef products such that ribeye and steaks
Lipid oxidation:
Lipid oxidation is typically
generated when the omega 3 fatty acids is high and the level of prooxidants is
in the large amount which not only deteriorate the quality but also produce
toxicity to that product, considered to build health risk factors. The
biological lipids are utilized at the process of refining and extraction; they
are LDLP, which are then after processing used for long storage. Regarding to
the human perception different complexes of antioxidant whether they are
dietary or enzyme antioxidant or are metal binding proteins inhibit the dietary
lipid oxidative products. Somehow, there are several circumstances, which bring
the biological problems i.e. cancer or heart diseases
Flavor
derived from fats:
The flavor changes in olive oil,
lard and beef fat depend on their oxidation state. The off-flavors are caused
by chemical changes that occur during chemical reactions. The flavor is
changed, when different constituents are added with in fats. The factors such
as cooking, manufacture method and enzymatic actions are influenced by the reactions
of milkfat. Flavor depend on aroma and taste. During churning, the butter
flavor is stronger than after few days in storage. This occur due the chemicals
reactions between flavor compounds or materials of butter
Flavor
derived from oils:
The flavor is more affect during
deep-frying which influences the oxidation. Different oils have different
oxidation characteristics with different flavor characteristics. The
composition of fatty acids in frying oils determine the amount of volatile
compounds that are produced during frying. The linoleic acid contributes the
most flavor to fried products as compared to linolenic acid and oleic acid. In addition
to saturated fatty acids, do not contribute as much as for the formation of
volatile compounds in oil. The composition of fatty acid affect the flavor but
there are some other factors that affect the flavor produced in fried products
and frying oil such as when lipids are exchanged between frying oil and food
materials, when the oxidized products of frying oil are interact with the constituents
of food materials and when polar products are absorbed in frying oil from food
materials
Flavor
derived from fatty acid composition:
The composition of fatty acids
cause flavor and off-flavor in oil. The flavor stability are measured by the
oxidative stability depend on the amount of volatile compounds. Polar compounds
in frying oil determine the stability of oil. The oil with low level of
linoleic acid impart good flavor. The oxidative stability of oil is improved by
decreasing the level of polar compounds and some other compounds such as
pentanal and hexanal. The increasing amount of oleic acid is directed related
to oxidative stability, volatile compounds and polar compounds. More the oleic
acid and less the linoleic acid gives the best flavor quality oil. More the
oleic acid and less the linolenic acid in canola oil have good flavor quality
and oxidative stability
Rancidity
and oxidation of fats and oils:
Oxidation of fats and oils cause
off-flavors that are caused by reaction of fats and oils in the presence of
oxygen. Rancidity is caused by off-flavor. When oil react with oxygen, it
called oxidative rancidity and when the enzymes and moisture are react in oil
called hydrolytic rancidity. Oxidation occur due to the presence of unsaturated
fatty acids. Off-flavors are detect early in oxidative rancidity as compared to
hydrolytic rancidity.
Primary
and secondary oxidation:
There are three steps by which flavor is affected. Alkyl
radical is formed by the reaction of light with oxygen that produce peroxy free
radical. Alkyl free radical and fat hydro peroxide are formed by the reaction
of freely unsaturated acids with peroxy free radicals. By this, the product
give off-flavor. The reaction will continue until the depletion of oxygen. These
are the three steps such as initiation, propagation and termination. Antioxidants
can stop the autoxidation because they act as free radicals scavengers. During
secondary oxidation, volatile compounds such as ketones, alcohols etc. cause
off-flavor in fats and oils. There are
some factors that affect the oxidative stability of oil that impact on flavor
such as composition of fatty acids, temperature, light, oxygen
Conclusion:
As we briefly discussed above
about the flavor of fats and oils. So we conclude that the flavor of fats and
oils depend on different factors, vary with different compositions and give
different flavor according to their oxidative stability. Prevent from oxidation
and rancidity by antioxidants. Degree of saturation is directly related to
firmness, stability and melting point. Degree of unsaturation is inversely
related to firmness, stability and melting point. The flavor is affected by
internal and external factors based on chemically, enzymatically, storage and
environmental conditions. Flavor is developed during frying and cooking of fat
and oil. Off-flavor depends on the rancidity, oxidation and volatile compounds
that depend on free fatty acids compositions and some other factors.
Recommendations:
- · Use antioxidants that prevent from oxidation
- · Provide proper storage conditions
- · Prevent from light and air
- · Take oil with good fatty acid composition
- · Proper frying
- · Use unsaturated fats and oils for better health
- · Prevent from rancidity by adding antioxidants
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