Nature and properties of novel protein resources.
Major conventional sources of protein in the diet in
developing and developed countries are cereals, meat, Pulses, milk and dairy,
fish, seafood, oil crops, vegetables, starchy roots, eggs, offals, fruit; but
they will not be sufficient enough in next decades. So it’s very important to
search the alternative sources of good quality of protein for human
consumption.
Some novel protein sources like insects, algae, duckweed,
microbial protein, my coprotein, leaf protein, and rapeseed are expected to
enter in food market as replacers for animal‐derived proteins. A wide variety
of vegetarian alternatives is also available on the market like seitan, tofu,
soy meat, tempeh, Quorn and meatless based on lupins, canola. However, food
safety aspects of these alternative sources of protein are not well‐known.
1.
Mycoprotein:
Mycoprotein is a form of single-cell protein, also known
as fungal protein. The nutritional value of mycoprotein, is found to be
comparable with eggs in amino acid composition, but contained no cholesterol
and had a substantial fiber content. Mushrooms are one of the most common fungi
which can be used as the source of protein as they have the high protein
content, usually around 20-30% by dry weight.
2. Single Cell
Protein
The center of attention has shifted towards microbes as
food sources for consumption as single cell protein (SCP). Currently, SCP is
being produced from many species of microorganisms like algae, fungi, and
bacteria. It is suitable to use fungi and bacteria for the production of SCP
when grown on economical waste products. Their quick growth and high protein
content have made them the major sources of SCP.
3. Leaf Protein Extract
Now a day’s
researcher processed study to extract protein from various fresh leaves of
plants. The protein content of the dried product from the sources is about
50-70%. The major problem face during leaf protein production its keeping
quality, shelf life, acceptability, and taste.
The amino acid profile of leaf protein concentrate
indicates that it is nutritionally superior to most cereal and legume seed
proteins; it can also compare positively with animal proteins except egg and
milk.
4. Insects Edible
Insects contain high-quality protein, vitamins and amino
acids for humans. Insects, a traditional food in many parts of the world, are
highly nutritious and especially rich in proteins and thus represent a
potential food and protein source.
From total nitrogen content of insects, approximately 93%
is unbound. The biological quality of insect protein is good, having chemical
scores from amino acid profiles, compared to the WHO/FAO/UNU pattern, that
range from 10% to 96%. The calcium, iron, and potassium contents are higher
than those of most food products of vegetable and animal origin. Insects are
also rich in vitamins of the B group such as niacin, riboflavin, and thiamin.
Thus, insects have the potential to improve people's diet by significantly
contributing to their protein intake and by reducing deficiencies of minerals
and vitamins.
Digestibility and basic precautions to be taken for digestion
experiments.
Digestibility refers to the amount of nutrient absorbed by the individual and is
generally calculated as the amount of nutrient consumed minus the amount of nutrient
retained in the feces.
1. The
initial step is to determine the total amount of feed stuff consumed and the
concentration of specific nutrient in feedstuff. One method to measure the
total amount consumed is, individually feed the animal and to measure the
amount fed and amount refused for each animal.
2. Next
step is to determine the total amount of feces excreted and the concentration
of specific nutrient in the feces. Another method is to collect and measure the
total amount of feces excreted. Measurements are expressed on dry matter basis
to correct for references in moisture contents.
3. Finally,
the values are put into following formula shown in figure:
The types of Digestibility are:
1.
True digestibility: It is measured as the difference between
intake and faecal output, with allowance being made for that parts of the
faeces that is not derived from undigested food residue (shed cells of the
intestinal tract, bacteria , residues of digestive juices). True digestibility
is always higher than apparent if any metabolic or endogenous components are
extracted in faeces.
2.
Apparent digestibility: It is simply the difference between
intake-feed and the output.
An additional method to measure apparent digestibility of
a nutrient is by using a marker or indicator. Add indigestible marker to feed
e.g. Chromic oxide. Measure its concentration in feed and feces, estimate
disappearance of marker from gut.
There are two
types of markers which are being used for digestibility in ruminants.
1- Internal markers which are compounds inherent to feed
stuff such as lignin.
2- External markers which are compounds supplemented to
the feed stuff such as chromic oxide.
NOTE: The marker must
be an inert compound.
The following equation is used to determine apparent
digestibility of a nutrient.
Digestibility (%)
=
The precautions to be
taken for digestion experiments are:
1. During selection of animals, animals with similar age,
body weight and sex should be preferred (Males are preferred more).
2. For feed selection maintenance roughage and concentrates
should be given. Likewise concentrates should not be more than 33%.
3. Duration of experiment must be sufficient:
i.e. Adaptation for trial: 7 days
Starvation
period: 24 hours
Trial
period: 7 days
4. Record of the feed provided, refused and excreta must
be properly maintained.
5. Sample subjected to proximate analysis should be
analyzed carefully.
6. For digestion trial of non-maintenance type of fodder
indirect method should be preferred.
7. Method of preservation of forage also affects the
digestion trial.
8. If the level of feeding is increased, digestibility of
the animal decreases. This should be considered.
9. Feed low in fiber are equally well digested by
ruminants and non-ruminants but more fibrous feeds are better digested by
ruminants.
nutritive
value and chemical composition.
Nutritive value is generally determined by feed composition,
intake and utilization efficiency of digested matter. Thus, the value of a feed
depends on chemical composition, digestibility, intake and efficiency.
|
S.N |
Chemical Composition |
Nutritive Value |
|
1. |
It is the general composition of feedstuffs
categorized into different components. |
It is evaluated by feeding animals. |
|
2. |
They are direct estimated values. |
They are indirect and apparent value. |
|
3. |
It is evaluated by feeding animals. |
It is just general composition of
feedstuff. |
|
4. |
It is laboratory process.
|
Sometimes it lacks real estimates |
|
5. |
It contributes to nutritive value. |
It depends on composition, intake and
utilization efficiency. |
|
6. |
Eg: CP, EE, CF, Ash, NDF. |
Eg: DCP,DE,ME,TDN |
Feed contaminants and their remedial
measures.
Feed contaminant is a substance which is not
intentionally added to food / feed, but is present in food as a result of
production (including operations carried out in crop husbandry, animal
husbandry and veterinary medicine), manufacture, processing, preparation,
treatment, packaging, transport or holding of such food or as a result of
environmental contamination.
1. Microbiological contamination
High-protein feed is particularly vulnerable to
contamination as it provides a very favorable environment for Salmonella.
Contaminated feed can cause infections in animals. This is particularly
problematic in the case of livestock as Salmonella may get into the animals’
milk, eggs or meat via smear infection. In addition to Salmonella, other
bacteria as well as yeasts and molds can also cause contamination in animal
feed. Monitoring of pathogenic microorganisms and the total bacteria count is
therefore an important task in the manufacture of animal feed.
2. Residues
Meat that is used to produce animal feed is subject to
strict controls, just as meat for human consumption. Nevertheless, it may occur
that residues of hormones, antibiotics or veterinary drugs are present in the
meat. ELISA
tests can detect a large number of such substances in a
timely manner. Furthermore, residues of plant protection products (pesticides)
or fertilizers (nitrate) may get into animal feed. Maximum residue limits
(MRLs) are established in the EU.
3. Mycotoxins
Mycotoxins are toxic metabolites produced by molds. They
can cause growth and fertility disorders in animals even in low concentrations.
Cereals are frequently infected by molds and may therefore be contaminated.
Mycotoxins can be detected quickly and easily on-site by means of lateral
flow tests. Through extensive controls and preventive
measures, mycotoxins rarely occur in animal feed nowadays.
4. Genetically modified organisms (GMO)
Soy meal, widely used in feed production, is often made
from genetically modified soybeans. Corn, canola and rice often originate from
genetically modified crops, too. Various GMOs are approved in the EU, but they
must be declared starting from a threshold of 0.9 %. Manufacturers producing
GMO-free feed must test their products accordingly. The method of choice for
this is real-time PCR.
5. Heavy metals
Heavy metals can be harmful for humans and animals and
may cause chronic poisoning. They get into feed via soils, fertilizers or
additives. Particularly lead has repeatedly been detected in animal feed. For
various metals, maximum levels are established in the EU and Feed regulation
Acts. So these contamination must be carefully monitored and taken in care.
6. Dioxins
Dioxins are organic pollutants that accumulate in the
environment and occur ubiquitously in soils, waters, plants and animals.
Contaminated animal feed above background levels should
be identified and, where necessary, excluded from entering in the food chain.
To reduce dioxins contamination in the environment, national authorities should
prevent uncontrolled burning of wastes, including the burning of landfill sites
or backyard burning, and the use of PCB treated wood for domestic heaters.
Areas with unacceptable dioxins contamination in the soil, water and air should
be identified and controlled. If necessary, agricultural production should be
avoided or restricted.
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