Milk, which is
one of the chief sources of calcium, is highly nutritious and constitutes a part
of our daily diet in some form or the other. The main constituents of milk are
water, proteins, lipids, carbohydrates, vitamins and minerals, which are
essential for growth and development.
Milk also
contains various biologically active compounds such as caseins and
whey proteins. Of the
total whey solids, it is estimated that about 75% is lactose. Milk is available
as full cream, skim, lactose-free and fat free milk. Condensed and evaporated
milk, which can be pasteurized or ultra-pasteurized are also readily available
these days. Cheese, yoghurt, buttermilk and sour cream are some of the products
made from milk.
In the
manufacturing of dairy products, there is usually a lot of damage to the
environment due to the generation of waste from livestock producers and the
by-products from
dairy
foods. Large amounts of these
by-products are generally discarded in the ecosystem, especially into the
rivers, lakes, seas or soil, causing considerable environmental pollution,
which not only affects the quality of water, air and soil, but even causes
climatic variations.
Research has
shown that lactose is one of the most polluting by-products due of its high
biochemical oxygen demand (BOD) < 35,000 ppm and its chemical oxygen demand
(COD) < 60,000 ppm. When it is discarded in the soil in the form of
industrial effluent without any prior treatment, it can modify the soil's physical
and chemical composition considerably, reducing to reduced crop yields.
In an effort to
reduce this environmental damage, scientists around the world are looking for
new biotechnological alternatives to utilize those by-products especially
industrial dairy waste to try and obtain different chemicals, which could have
various potential industrial applications.
Biomass: In the process of olive oil extraction, it is found that nearly 80%
of waste is generated which is known as oil press and nearly half of this is
composed of water. One of the fungus
Geotrichum candidum acts on this
substrate, namely oil press waste and milk whey to produce biomass thereby
reducing pollution levels.
Bioplastics: Bacillus megaterium SRKP-3 acts on industrial dairy waste as
a substrate to produce polyhydroxybutyrates (PHB), which is a biodegradable
type of plastic.
Brevibacterium casei SRKP2 acts on industrial waste
milk as a carbon source to produce PHB. This discovery is highly useful in the
medical field because the products were used to produce nanoparticles of PHB to
facilitate drug delivery to any part of the body.
Biofuels and
bioenergy: The combustion of biofuels releases less
polluting agents into the environment than burning fossil fuels; however, the
rate limiting factor has been the high cost of raw materials which is used to
produce these biofuels. Dairy waste is a viable solution, which is used as a
substrate for fermentation by yeast like
Kluyveromyces fragilis to
produce ethanol.
Another way to
reduce greenhouse gas emissions and contamination of soil and
aquatic
ecosystems by fossils fuels is by using dairy wastes to produce
hydrogen as a biofuel.
Microbial fuel
cell technology has been developed to obtain bioelectricity from milk wastes, thus providing new alternatives for the use of
electric energy.
Biosurfactants: Biosurfactants (BS) have shown promising role in bioremediation and
oil recovery processes due to their surface activity, biodegradability,
antimicrobial effects, amongst others. Bacteria such as
Pseudomonas
aeruginosa and its recombinant strain have been able to synthetize BS with
milk whey waste obtained from the cheese industry.
Bioactive
peptides: Bioactive peptides (compounds of protean
nature with biological activity found in milk and in its derivatives) not only
have a nutritional function but possess various biological properties such as:
anticancer effect, antimicrobial property,
antihypertensive effect, regulation of immune system,
antimicrobial activity, neurotransmitter generation, amongst others. A
proteolytic vegetal enzyme from
Maclura pomifera is used to produce a
bioactive peptide from dairy waste.
Thus, this
article shows how dairy by-products can be used to obtain valuable chemical
compounds in the fields of health, pharmaceuticals, food, plastics and fuels.
This goes a long way in decreasing environmental pollution and reducing the
damage caused by man. However, before these methods are scaled to industrial
levels, further studies would be essential for optimization of culture conditions
and development of microbial strains in an effort to generate maximum yields in
a cost-effective manner.
Reference:
http://www.scirp.org/Journal/PaperInformation.aspx?PaperID=55189#.VUtcEvBgbIUaperID=
46411.VUtcrfBgbIU
http://www.betterhealth.vic.gov.au/bhcv2/bhcarticles.nsf/pages/Milk_the_facts_and_fallacies
Source: Medindia
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