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4 ways of assessing protein quality
Table of Contents
1. Protein growth performance factor (PER)
Protein efficiency ratio (PER) is the ratio of body weight gain in grams when consuming a particular type of protein. This method of assessing protein quality is used by baby food manufacturers. To calculate this ratio, young animals, mostly rats, are fed a diet in which 10% of the energy comes from a protein source studied. Body weight is measured over time and then compared to the amount of protein consumed. Apart from young children, this indicator is not widely used in human nutrition. PER = Body weight gain (grams) / quantity of protein from the product studied (grams).2. The biological value of protein (BV)
Biological value (BV) is one of the most common methods for assessing protein quality. It tells how much protein, specifically nitrogen, that is absorbed into the bloodstream, is actually preserved in the body. For example, it reaches the muscles permanently. It measures and compares the amount of nitrogen that's absorbed and the quantity of nitrous oxide that is preserved. This factor is mainly calculated in animals, although it is sometimes also shown in humans.3. Use of net protein (NPU)
Net protein utilization (NPU) is very similar to the previous indicator. whereas BV compares the amount of nitrogen retained to the nitrogen absorbed by NPU it compares to the ratio of conserved nitrogen to the total amount of protein consumed. in a sense it is more useful because BV can give a high rating to the product chosen only because a small amount of the protein is absorbed from it.4. Adjusted protein amino acid appetite index (PDCAAS)
The most recent and currently most commonly used method of assessing protein quality. is to compare the amount of limiting amino acid in a protein under study against the amount in the same amino acid of the reference protein, which is mainly egg or milk. The resulting value is then multiplied by the absorbability of the protein under test. Although this is probably the best method to assess protein quality, it has its drawbacks. The first is the fact that the highest possible amino acid content is 1.0. No product can achieve the exact amount of amino acid, regardless of its actual quality. Amino values that exceed 1.0 are found in the reference product PDCA gmg therefore, this actually occurs over and over. For some protein compounds, there is no known limiting protein content.
