PER-value

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). 

The sulfur amino acid content of soy protein can be enhanced by preparing plasteins from soy protein hydrolysate and sources of methionine or cystine, such as ovalbumin hydrolysate (plastein AB), wool keratin hydrolysate (plastein AC), or L-methionine ethyl ester [3082-77-7] (alkaU saponified plastein) (153). Typical PER values for a 1 2 mixture of plastein AC and soybean, and a 1 3 mixture of alkah-saponified plastein and soybean protein, were 2.86 and 3.38, respectively, as compared with 1.28 for the soy protein hydrolysate and 2.40 for casein. 

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. 

Of the 190 accessions evaluated after one year s growth in Florida, 38 showed tuber formation. Tender leaves are incorporated in the food preparations in the South Asian region. Leaf protein concentrate (crude protein 51.9%) prepared from leaves yielded a PER value of 2.2 in comparison to 2.7 for corn-soy control. International Winged Bean Trials conducted in 19 countries recommend 5 varieties as having the best yield potential under varying environmental conditions. 

Sample description Reported PER values Corrected PER values Reference... 

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. 

Feeding studies with the rat as the test animal verified the high nutritional quality indicated by the amino acid pattern (45). Using isolates and concentrates prepared from Jewel and Centennial cultivars, PER values were equal to that of casein (milk protein) (Table IV). Examination of the amino acid patterns of sweet potato protein and casein revealed that both contained... 

Preliminary analysis of the geochemical data indicated that Ti and Nb, significantly concentrated in fine-grained rutile-anatase, were the most conserved elements during hydrothermal alteration and weathering. Due to its greater abundance and lower relative analytical error, Ti was selected as the conserved denominator element in the PER analysis. Changes in PER values for major- and trace-elements with distance from ore are listed in Table 1. 

PER values are often adjusted relative to casein, which may be given a value of 2.5. 

The final PER value is an average of the weight gain and protein intake of the entire test group at day 28. 

Net protein ratio (NPR) is used to correct PER values for the amount of protein required for cell maintenance. NPR is often run in conjunction with a PER. The experiment requires that one additional set of animals be added as a treatment group. This group of animals is fed a basal diet with no protein (zero protein or basal diet). Results from RNPR are similar to net protein utilization (NPU) and biological value (BV methods, see Alternate Protocol 4). A 2-week RNPR is thought to be the most appropriate rat test for routine assessment of protein quality. 

Figure 2.10 -trajectories for the resonance energy (Stark effect in the hydrogen atom), where N is the number of basis functions per /-value, for more details see Ref. [67]. Taken from Reinhardt [67] with permission of IJQC. 

Egg protein is one of the best quality proteins and is considered to have a biological value of 100. It is widely used as a standard, and protein efficiency ratio (PER) values sometimes use egg white as a standard. Cereal proteins are generally deficient in lysine and threonine, as indicated in Table... 

The protein efficiency ratio (PER) of sesame seed protein is 1.86 (35). The PER value can be raised to 2.9 when sesame seed protein is supplemented with lysine (36). El-Adawy (37) added sesame products including sesame meal, sesame protein isolate, and protein concentrate to red wheat flour to produce flour blends. It was found that water absorption, development time, and dough weakening were increased as the protein level increased in all blends however, dough stability decreased. Sesame products could be added to wheat flour up to 16% protein without any detrimental effect on bread sensory properties. The addition of sesame products to red wheat flour increased the contents of protein, minerals, and total essential amino acids the in vitro protein digestibility also increased significantly. 

IChemE metrics of sustainability consist of 49 indicators classified into three main categories economic, environmental and social. The environmental indicators within the IChemE metrics are similar to those in the CWRT metrics. However, there are some differences. The IChemE metrics include the area of land as an environmental indicator. The actual indicators are (i) the sum of directly occupied and affected land per value added and (ii) the rate of land restoration. Other differences relate to the assessment of the relative impacts of pollutants on the environment and human health. The IChemE indicators do not take into account the life-time of chemicals in various media of the environment. The human health indicator is limited to carcinogenic effects and is normalized to benzene. 

Rapidly growing cultures (Table 2, exp. phase) show PER values from 2 -10 in most cases,but may increase to 10-30 in some cases. Mague et al. [22] concluded that extracellular release is a normal function of healthy cells and showed that the relative composition of Skeletonema costatum cellular and the extracellular fraction of amino acids was quite different. Marlowe et al. [23] fractionated cellular and extracellular material and found a marked difference in the content of ionic compounds in the two fractions. Myklestad et al. [24] found the reserve polysaccharide P-l,3-glucan to be quite dominating in the soluble cellular fraction of Chaetoceros affinis while the extracellular polysaccharide produced was entirely different and contained no glucose at all in the molecule... 

Generally these values are higher than PER values from cultures in the exponential phase (Table 2), while stationary phase cultures may show higher PER than the actual field values shown in Table 5.1 assume that the varying physiological state of phytoplankton populations in the field is one of the important factors in determining the relative release rate (PER). 

It is well estabhshed that phytoplankton cells hmited in N or P may continue the photosynthetic production of cellular and extracellular compounds not having the hmiting nutrient as a constituent, often leading to high PER values. On the other hand, the specific exudation rate may not be higher than under nutrient replete conditions. High medium N/P ratio has been shown to increase the production of extracellular polysaccharides. 

Protein Quality. The protein quality of soybeans at different stages of maturity is shown in Table VII. Sulfur-amino acid content was Independent of maturity. In the raw form, protein quality was very low for immature, mature, and germinated soybeans. After heat treatment, PER values were Increased to... 

Soybeans present an intermediate pattern with respect to the effect of germination on protein value of the beans, in that PER values of ungerminated and germinated soybeans are not significantly different (Table VII). Apparently, a slower proteolytic degradation of the major reserve proteins in germinating soybeans had little effect on protein digestibility. 

In contrast to most studies, Ellas et al. (58) reported that PER values In cooked common beans (Phaseolus vulgaris, variety... 

After 3 days of germination, PER values decreased in both raw and cooked forms of green gram, cowpeas and chick peas. 

The agile paradigm in contrast is applied downstream the decoupling point as the demand varies significantly and the product variety per value stream has augmented. 

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