Protein efficiency ratio

Protein efficiency ratio (PER) = weight gain(g) for a 10% protein level in the diet of rats as compared to the standard of 2.5 for casein. 

Table 11 presents data on the protein quaUty of a variety of LPC products obtained from rat-feeding studies. Typical protein efficiency ratio (PER) values for LPCs derived from alfalfa range from 1.41 without supplementation to 2.57 with 0.4% methionine added casein can be adjusted to a PER of 2.50 (98,100). Biological values (BV) of mixtures of LPCs, such as barley and rye grass or soybean and alfalfa, maybe higher than either LPC alone. The effect has been attributed to the enhanced biological availabihty of lysine in these mixtures (99). 

A significant problem is the wide variation in properties in the same type of product both from different manufacturers and from the same source. More recendy there has been vast improvement in the consistency of these products from a given manufacturer and usage in dairy substitutes is expected to expand. These isolates do have a higher protein efficiency ratio (PER) than casein and are equal to egg protein. 

BOLING-FRANKENBACH S D, PETER 0 M, DOUGLAS M W, SNOW J L, PARSONS C M, BAKER D H (2001) Efficacy of phytase for increasing protein efficiency ratio values of feed ingredients. Poult Sci. 80 1578-84. 

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. 

Protein contents of selected oilseeds and legume seeds, and food protein ingredients prepared by various procedures, are shown in Table I. Amino acid contents and protein efficiency ratios (PER s)... 

Table II. Essential Amino Acid Profiles (g/16g N) and Protein Efficiency Ratios of Various Protein Food Ingredients...

The same shipment of raw, cooked and roasted glandless whole kernel cottonseed flours used in the FDA study was used to determine the protein efficiency ratio (PER) of each flour (8). The adjusted PER (Table II) of cooked (2.10) cottonseed was significantly higher than roasted (1.77) cottonseed. Protein retention efficiency (PRE) for roasted cottonseed (58.08) was lower than values for raw (60.54) and cooked (62.95) cottonseed. Relative protein values (RPV) indicated a utilization of 91, 91 and 96% of the protein in raw, roasted and cooked cottonseed, respectively. The multiplication of the (RPV) percentage utilization and the protein content of the cottonseed (Table I) results in the relative utilizable protein values (Table II). 

Table II. Average Protein Efficiency Ratio (PER), Relative Protein Value (RPV) and Relative Utilizable Protein for Raw, Roasted and Cooked Whole Kernel Cottonseed3...

Table III. Average Adjusted Protein Efficiency Ratio for Raw, Cooked and Roasted Cottonseed Supplemented with Lysinea...

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... 

Walter et al. (38) measured the protein efficiency ratio (PER) of flour prepared from sweet potatoes which were cooked in a drying oven. Because the PER is determined on the basis of a diet containing 10% protein, the Jewel and Centennial sweet potatoes used in this study were stored until sufficient starch had metabolized to increase crude protein content to 11.25% (dry basis). When the flour was fed to Sprague-Dawley strain rats, the corrected PER values were 2.22 and 2.00 for Centennial and Jewel cultivars, respectively, compared to 2.50 for casein. Centennial had the highest PER value of the two cultivars because its NPN content was lower. The net effect of increased NPN content is to lower the amount of essential amino acids as a percentage of the total nitrogen and thus decrease the PER value. 

Recent nutritional evaluations of cucurbit seeds have accentuated the currently popular Buffalo gourd ( . foetidissima) and are shown in Table III. PER (protein efficiency ratio) values of full-fat and natural and autoclaved fat-free meals fed to weanling... 

At least 2.7% milk-derived protein having a protein efficiency ratio (PER) not less than that of whole milk protein, 108% of that of casein. 

Basic Protocol 1 Using Protein Efficiency Ratio (PER) to Determine... 

A number of procedures used to determine protein quality involve bioassays. Bioassays require feeding live animals protein ingredients for a specified period of time, and then estimating the nutritive value of the protein. Two such assays are the rat-based protein efficiency ratio (PER) bioassay and the human nitrogen balance assay (Dimes et al., 1994). Animal feeding experiments require chemical analyses of both the dietary inputs and then the metabolic output of the animal (e.g., body composition analysis, fecal sample analysis, collection, and assay for urine) from which the efficiency of protein metabolism can be predicted as well as how the protein supports animal growth and cell maintenance. 

USING PROTEIN EFFICIENCY RATIO (PER) TO DETERMINE PROTEIN QUALITY... 

Protein efficiency ratio and in vivo digestibility methods... 

Protein efficiency ratio (PER), see Protein quality analysis... 

PTFE polytetrafluoroethylene PUFA polyunsaturated fatty acid PV peroxide value PVDF polyvinylidene difluoride PVP polyvinylpyrrolidone PVPP polyvinylpolypyrolidone RAS retronasal aroma stimulator RDA recommended dietary allowance RF radio frequency RFI relative fluorescence intensity RI retention index RNU relative nitrogen utilization ROESY rotational nuclear Overhauser enhancement spectroscopy RP-HPLC reversed-phase HPLC RPER relative protein efficiency ratio RS resistant starch RT retention time RVP relative vapor pressure S sieman (unit of conductance)... 

Daniel, V. A., Urs, T. S. S. R., Desai, B. L. M., Rao, S. V., Rajalakshmi, D., Swaminathan, M., and Parpia, H. A. B. (1967). Studies on lost cost balanced foods suitable for feeding weaned infants in developing countries. The proteins efficiency ratio of low cost balanced foods based of ragi or maize groundnut, Bengalgram, soya and Sesame flours and fortified with limiting amino acids. J. Nutr. Diet. 4,183-188. 

Citrus juices and their products cannot be considered significant dietary sources of protein because the protein efficiency ratio (PER) of citrus protein is less than 20% that of casein (23, 41). 

Protein efficiency ratios of conventionally baked, microwave-baked, and steamed breads, presented in Table II, were 0.79, 1.20, and 1.25, respectively. The significantly lower PER of conventionally baked breads indicates that more... 

Table II. Protein efficiency ratios of bread-diets fed rats 28 days...

Table IV. Protein efficiency ratios and digestibility of bread diets...

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