Quality protein

The quality of different proteins can be expressed according to their chemical score, protein efficiency ratio (PER), biological value (BV), and net protein utilization (NPU). These parameters refer to the different tests used to define the protein s quality. The chemical score refers only to the property of the protein in question. The PER, BV, and NPU refer to relationship.s between the dietary protein and the consumer. The values of the PER, BV, and NPU depend on properties of both the protein in question and the needs of the animal. The chemical score, PER, BV, and NPU of proteins in various foods, including eggs, fish, rice, and maize, are listed in Table 8,1 3. 

The value of the chemical score is determined by a chemical test. The chemical score for a particular food or protein would not be expected to vary much when determined by different researchers. The PER, BV, and NPU are biological tests and involve animal feeding trials. I he BV and NPU require nitrogen balance measurements, and hence their determination requires more work than the other tests. The values for the PER, BV, and NPU might be expected to vary somewhat with different determinations however, the relative order of the different foods in Table8.13 might not be expected to change much w hen the PER, BV, and NPU arc determined by different researchers. 

StfUitr Conuruttee n Amino Acids, Fond and Nutrihon Boani (1974). 

The Chemical Scott and the Concept of the Limiting Amino Acid 

The chemical score is determined as follows. The contents of the indispensable amino adds of egg albumin (ovalbumin), which is used as a reference protein, and the food protein in question arc determined. Egg albumin is considered to be ideal and nutritionally complete The test requires several steps. The protein must be purified, hydrolyzed to the constituent amino acids, and then subjected to analysis using an amino acid analyzer. The values for each of the indispensable amino acids for ovalbumin and the test protein are then listed as shown in Table 8.14. The contents of the various amino acids in the two proteins are then compared. The amino acid in the test protein that is present in the low cst level, on a percentage basis, can be found by examining the table. This amino acid is called the limiting amino acid of the protein. The value of the percentage is the chemical score. Table S.14 indicates that the quantity of lysine in oat protein is 51% that in egg protein. Hence, the chemical score of oat protein is 51, 

Source-. Committee on Amino Acids, Food and Nutrition Board (1974). 

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Table 8. Protein Quality and Digestibility of Nonphotosynthetic Microorganisms...

Protein trafficking is the transport of proteins to their correct subcellular compartments or to the extracellular space ( secretory pathway ). Endo- and exocytosis describe vesicle budding and fusion at the plasma membrane and are by most authors not included in the term protein trafficking. Protein quality control comprize all cellular mechanisms, monitoring protein folding and detecting aberrant forms. 

The UPS also plays a major role in protein quality control. In a process known as endoplasmic associated degradation (ERAD), misfolded proteins, which are formed in the endoplasmatic reticulum, are translocated back to the cytoplasm and degraded by the proteasome. 

Qi, P. X. and Onwulata, C. 1. (2011). Physical properties, molecular structures and protein quality of texturized whey protein isolate (WPl) Effect of extrusion moisture content. /. Dairy Sci. (Accepted for publication). doi 10.3168/jds.2010-3942. 

Birds eat sufficient food to satisfy their energy intake, but this does not mean that they will eat enough protein, unless the protein proportion in the rotation is high. Protein quality is also important, the two most essential amino acids being lysine and methionine. The best quality protein for all poultry is white fishmeal (banned only for ruminants by the Soil Association). The best vegetable protein is soya bean which is low in methionine, but this can be made up by using sunflower meal in the ration. 

Patent flour has two classes of use. It can be used to make whiter bread or where very high protein content is required. The use of patent flour to make bread seems to be dying out. Its use does, however, remain popular in South Wales. There are various examples of products where patent flour is used for its protein quality, e.g. filo pastry and West Indian patties. Both of these products are brown so the colour of the flour is not important. 

The protein efficiency ratio (PER) of field pea flours is considerably less than that of casein (1.46 vs. 2.50), and somewhat less than that of soy flour (1.81). However, composites of wheat flour and pea or rice and pea (50% of the protein from each source) had PER s of 2 or more (22). Thus, supplementation of cereals with pea flour results in improvement of protein quality. 

Cooked glandless cottonseed protein quality was superior to that of raw and roasted cottonseed. The roasting process adversely affected protein quality. Supplementation of roasted cottonseed with 0, 0.2, 0.4, 0.6 and 0.8% L-lysine indicated a peak PER response at 0.45%. The adverse effect of roasting on the protein quality of cottonseed was overcome by addition of L-lysine which made the protein... 

Cottonseed, peanut, sesame seed, and soybean flours, when used as supplements, add to the quality of the protein. The improvement of protein quality was due to the flours compensating for limiting amino acids. Supplementation using various flours improved total protein, amino acid content and some physical characteristics in akamu, yeast bread and sugar cookies. 

Law 480 blends corn-soy and corn-soy-milk, with respect to protein quality by animal assay, organoleptic quality and storage... 

Three animal procedures (protein efficiency ratio, net protein ratio, and protein digestibility) were used to evaluate protein quality. The AOAC (13) animal assay for protein efficiency ratio... 

Hayes, R.E Spadaro, J.J. Wadsworth, J.I. Freeman, D.W. "A study of nine Corn-Based Food Blends Formulated by Computer for Maximum Protein Quality," Agri. Research Results (South.Ser.) ARR-S-18, U.S. Department of Agriculture, 1984. 

Protein quality studies evaluating various edible portions of the winged bean plant and the results of recent International Field Trials are reviewed. Research efforts have been focused upon the mature seed (protein content 20.7-45.9% in 240 accessions), which is occasionally eaten in parts of Indonesia and Papua, New Guinea. Autoclaved seed meal and wet heat treated seed meal provided a corrected PER value of 1.76 and 1.72 respectively, in comparison to casein control of 2.50. 

Previously published reviews (59-61) have analyzed in detail the emergence of winged bean as a legume of significant potential. This paper summarizes recent reports on protein quality evaluation of the edible portions of this legume. 

Tubers Tubers are quite commonly consumed by villagers in Burma. Other tropical countries also report sporadic use of winged bean tubers (59). However, in comparison to the available data on the nutrient, anti-nutrient composition and the protein quality of the seed flour, published data on the nutritional value of winged bean tuber is somewhat limited. The few reported studies dealing with a larger number of varieties grown in different locations (25,67-71) show that tubers are mainly composed of protein and carbohydrates. 

Kostova, Z. and D. H. Wole, For whom the bell tolls protein quality control of the endoplasmic reticulum and the ubiquitin-proteasome connection. Embo J, 2003, 22(10), 2309-17. 

Cyr, D. M., Hohfeld, J. and Patterson, C. Protein quality control U-box-containing E3 ubiquitin ligases join the fold. Trends Biochem Sd 2002, 27, 368-75. 

Hampton, R. Y. ER-associated degradation in protein quality control and cellular regulation. Curr Opin Cell Biol 2002, 34, 476-82. 

M. R. Protein quality control Triage by chaperones and proteases. Genes e[ Development 1997, 11, 815-823. 

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