Saturday, March 7, 2009

How to Improve the Nutritional Value of Cereals and legumes

In human nutrition, cereals and legumes provide a major part of the dietary protein requirement. The storage proteins of these seeds are a good source of essential amino acids. But some of these legumes and cereals create deficiency of some essential amino acids and therefore such cereals and legumes are considered to be poor in quality, even though they are rich sources of dietary protein. They cannot provide a balanced diet. In such cases the diet should be supplemented with other sources of essential amino acids. In some other cases certain rich sources of protein may not be suitable for human consumption because of toxicity, a bad quality such as bad smell, taste, etc. Thus, protein for human consumption should be safe and nutritious.

The major parameters for assessing the general effectiveness of a protein as a dietary protein are the Essential Amino Acids Profile (EAAP), Biological Value (BV), and Protein Efficiency Ratio (PER).

Essential Amino Acids :
Proteins are composed of 20 amino acids. Plants and microbes can synthesize all these amino acids, but animals cannot. Such amino acids have to be supplemented through the diet. Such amino acids are the essential amino acids. The presence of a high percentage of essential amino acids along with other amino acids increases the nutritive quality of protein for human consumption.

The nutritive quality of whey proteins is considered to be higher compared to other types of proteins. They are rich in branched chain amino acids-Ile, leu, val, lys and trp. The branched chain amino acid (BCAA) is needed for rapid energy metabolism for muscular activity. BCAA helps in the bio-availability of complex carbohydrates absorbed by muscle cells for anabolic muscle building activity. BCAA plays an important role in the production of metabolic energy during rapid muscular actions. During exercise BCAAs are released from the muscle cells. The carbon chain part of the molecule is used as fuel and the nitrogen part is used to synthesize alanine. Alanine is transported to the liver where it is turned into glucose to meet the energy requirements. So athletes are advised to take BCAA sources before and after exercises to protect their healthy body. Thus, BCAAs are very important for muscle growth and muscular activity.

Biological Value :
Biological value or BV is a measure of protein nitrogen retained by the body after consuming a particular amount of protein nitrogen. Among various types of dietary proteins whey protein showed the maximum BV compared to rice, soy, egg, and wheat proteins.

Protein Efficiency Ratio:
Protein efficiency ratio or PER is a measure of the efficiency of a protein on the rate of growth. It is the growth performance in terms of weight gain of an adult by consuming 1 gm of dietary protein. The order of PER for various dietary proteins is given below.

Wheat protein :
The quality of protein can be improved by the modem approach of protein engineering through recombinant DNA technology. The storage protein of cereals and legumes can be modified by introducing essential amino acids. These genes can be transferred to food plants to be expressed in the respective storage parts of the plants such as seeds, tubers, or grains. Modifications in proteins can be made by introducing new amino acids or by substituting the existing amino acids with new ones. Efforts are already being made to enhance the nutritive quality of protein genes in maize and other similar food grains. Scientists are on the look out for new types of dietary protein genes that are rich in essential amino acids, with which the nutritive quality of other plants can be increased.

Tags: Bio Technology, Bio Genetics ,Protein Designing

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