Nutritive value of protein fractions extracted from soybean,rapeseed and wheat flours in the rat

The nutritive value of various protein fractions was studied. Fractions 2S and 12S from rapeseed, 2S, 7S and 11S from soybean were obtained by dissolution in ammonium sulfate solutions. Albumin-globulin, gluten, glutenin and gliadin fractions from wheat were obtained by dissolution in salted water (albumin-globulin), acetic acid (glutenin) and alcohol (gliadin). Liveweight gains, protein efficiency ratio (PER) and apparent digestibility coefficient (ADC) were used as measures of the nutritive value. The protein fractions had a lower nutritive value than the unfractionated proteins except for the albumin-globulin fraction of wheat which had a nutritive value higher than that of the unfractionated wheat protein. PER obtained with the rapeseed 2S and 12S fractions were 2.49 and 2.21, respectively, as compared to 2.64 for unfractionated rapeseed. With soybean fractions, PER were 0.92 for 2S, — 0.007 for 7S and 1.47 for 11S, as compared to 2.19 for the original protein. The wheat albumin-globulin fraction gave a PER of 2.78, as compared to 1.45 for the unfractionated wheat protein. Gluten, glutenin and gliadin fractions had a lower PER than that of unfractionated wheat protein. ADC of all fractions were higher than those of the original proteins. The difference in liveweight gains and PER observed between protein fractions can be partially explained on the basis of the essential amino acid content.     

Nutritive value of rapeseed proteins and fractions supplemented with methionine and tyrosine in rats

Rapeseed protein concentrate (RPC), rapeseed 2S and 12S fractions, a blend of 2S and 12S fractions, retentate (RET) and precipitate (PRE) proteins obtained during rapeseed fractionation were compared to casein for nutritive value as determined by net protein ratio (NPR) and apparent digestibility coefficient (ADC). Tyrosine concentration in rapeseed 2S fraction was the lowest compared to all other protein sources and methionine was the first limiting amino acid. The NPR and ADC of RPC, RET, and fraction 12S did not change significantly (P<0.05) following supplementation with methionine, but for PRE the NPR was decreased significantly (P<0.05). However, the rapeseed 2S fraction supplemented with tyrosine had a NPR significantly (P<0.05) higher than that of RPC and not significant (P<0.05) different from that of casein. The NPR of the 2S and 12S blend was significantly (P<0.05) higher than that of RET and PRE; however, no significant (P<0.05) difference was observed in NPR and ADC of the blend when supplemented with tyrosine. The nutritive value and digestibility of rapeseed 2S fraction were improved by supplementation with tyrosine and by blending with the 12S fraction.     

Nutritive value of soybean,rapeseed and wheat proteins,and various blends of these vegetable proteins and their fractions in rats

Blends of vegetable proteins were prepared to improve the nutritive value of these proteins. Soybean flour, rapeseed protein concentrate, whole wheat flour, soybean 2S+11S extract, wheat albumin-globulin + glutenin (AG+G) functions, and some of their blends were compared to casein for protein efficiency ratio (PER) and apparent digestibility coefficient (ADC). Autoclaving (1 h) soybean proteins was also studied. Casein and rapeseed protein concentrate gave the highest weight gains and PER. Other protein sources gave lower values for both PER (P<0.05) and weight gain. The digestibility of all vegetable proteins was lower (P<0.05) than that of casein. PER of soybean 2S+11S extract was significantly lower (P<0.05) than that of soybean flour. Autoclaving significantly (P<0.05) improved the PER of both soybean flour and 2S+11S extract. The ADC of autoclaved 2S+11S extract was similar (P<0.05) to that of autoclaved soybean flour and significantly higher (P<0.05) than that of 2S+11S extract. Soybean flour had the lowest (P<0.05) ADC. Heat treatment destroyed antinutritional factors, probably trypsin inhibitors and/or haemagglutinins of soybean. This was accompanied by improvement in the nutritional value of protein. The four blends were chosen on the basis of amino acid composition, chromatography of proteolyzates and nutritive value of each fraction. The PER of wheat albumin-globulin and glutenin (AG+G) blend was similar (P<0.05) to that of wheat flour and lower (P<0.05) than that of all other blends used. Wheat AG+G+rapeseed protein concentrate and wheat AG+G+soybean flour blends gave the highest (P<0.05) PER. Wheat AG+G improved the PER of 2S+11S extract and of soybean flour but decreased the PER of rapeseed protein concentrate. Wheat AG+G and wheat AG+G+rapeseed protein concentrate blends gave an ADC significantly higher (P<0.05) than that of wheat AG+G blend containing soybean flour of 2S+11S extract. However, blending wheat AG+G with either 2S+11S extract of soybean flour improved ADC.     

Specific role of endopeptidases in modulating the nature of protein digestion products

The impact of various endopeptidases on the nature of protein digestion products was measured with the digestion cell technique. After a 30 min pepsin pre-digestion, casein and rapeseed concentrates were hydrolyzed with various amounts of pancreatin, trypsin and/or chymotrypsin. This hydrolysis was performed in a dialysis tube (molecular weight cut-off 1000) with continuous collection of the digested material. The addition of pure trypsin or chymotrypsin to pancreatin (Enzyme:Substrate 125) did not change the digestibility of casein. Only a higher pancreatin level (Enzyme: Substrate 112.5) increased the total protein digestibility without affecting the amino acid spectra. Rapeseed digestibility was markedly increased by the addition of pure trypsin to pancreatin. Lysine and arginine, target amino acids of trypsin, were favored at the expense of chymotrypsin and elastase target amino acids. Supplementation of pancreatin with, chymotrypsin enhanced rapeseed digestibility without affecting the relative amino acid digestibility. The impact of a higher pancreatin ratio (Enzyme: Substrate 112.5) was similar to that of enriched pancreatin but the rate of amino acid release was modified. The differences between protein sources were mainly attributed to protein structure.     

Relationship between amino acid scores and protein quality indices based on rat growth

Protein efficiency ratio (PER), relative PER (RPER), net protein ratio (NPR) and relative NPR (RNPR) values, and amino acid scores were calculated for 20 food products (casein, casein + Met, beef salami, skim milk, tuna, chicken frankfurters, sausage, heated skim milk, peanut butter, rolled oats, soy isolate, chick peas, pea concentrate, kidney beans, wheat cereal, pinto bean, lentils, rice-wheat gluten cereal, macaroni-cheese, and beef stew). In most cases, PER, RPER, NPR or RNPR ranked the products in the same order and positive correlations among the protein quality methods were highly significant (r=0.98–0.99). Amino acid scores (based on the first limiting amino acid, Lys-Met-Cys, Lys-Met-Cys-Trp or lys-Met-Cys-Trp-Thr) were positively correlated to the PER, RPER, NPR or RNPR data (r=0.61–0.75). Inclusion of the correction for true digestibility of protein improved the correlations between amino acid scores and the indices based on rat growth. The correlations were especially high between Lys-Met-Cys scores (corrected for true digestibility of protein) and PER, RPER, NPR or RNPR (r=0.86–0.91). Inclusion of the correction for true digestibility of individual amino acids did not result in further improvements of the correlations in most cases. It is concluded that adjusting amino acid scores for true digestibility of protein would be sufficient and further correction for digestibility of amino acids would be unnecessary in mixed diets.This paper was presented in part at the 71st annual FASAB meeting, Washington, DC, March 29–April 2, 1987.     

Digestibility of protein and amino acids in selected foods as determined by a rat balance method

Values (%) for true digestibility of crude protein and individual amino acids in 20 selected foods were determined by the rat balance (fecal) method. The products were fed as the sole source of protein in diets containing 8% crude protein (N × 6.25). Lowest true protein digestibility values (79–84) were obtained for pinto beans, kidney beans and lentils; intermediate values (89–92) were obtained for chick peas, beef stew, skim milk (over heated), rolled oats, whole wheat cereal, and pea protein concentrate; and highest values (94–100) were obtained for sausage, macaroni-cheese, rice-wheat gluten cereal, skim milk, tuna, soy isolate, peanut butter, chicken frankfurters, beef salami, casein and casein + methionine. In animal foods, peanut butter and soy isolate, the differences between true digestibility of crude protein and most individual amino acids were less than 5%. However, the values for true digestibility of methionine and cystine were up to 44% lower than those of crude protein in pinto beans, kidney beans, lentils, chick peas and pea concentrate. In these legumes, digestibility of crude protein was not a good predictor of digestibility of the limiting amino acids.     

Evaluation of pumpkin seed products for bread fortification

Pumpkin seed products (raw, roasted, autoclaved,germinated, fermented, pumpkin protein concentrate and pumpkin proteinisolate) were incorporated into wheat flour to produce blends with proteinlevels of 15, 17, 19 and 21%. Dough properties were evaluated by afarinograph; loaves of breads were evaluated by a taste panel for crustcolor, crumb color, crumb texture, flavor, and overall quality. Resultsindicated that pumpkin seed products can be added to wheat flour up toa 17% protein level for raw, roasted and autoclaved pumpkin meal, 19%level for germinated, fermented and pumpkin protein concentrate and21% level for pumpkin protein isolate without a detrimental effecton dough or loaf quality. On the other hand, the addition of pumpkin seedproteins resulted in increasing protein, lysine and mineral contentscompared to the control. While lysine and tryptophan were the first andsecond limiting amino acids in the control bread, tryptophan and lysinewere the first and second limiting amino acids for raw, roasted, autoclaved,germinated and fermented pumpkin meal; valine and lysine and valine andtotal sulfur amino acids were the first and second limiting amino acids forpumpkin protein concentrate and isolate, respectively. In vitro protein digestibility improved when the pumpkin seed proteinswere added.     

Nutritive value of acetylated and hydrolysed rapeseed proteins in rats

Acetylated, hydrolysed and unmodified rapeseed proteins were compared to casein for nutritive value as determined by net protein ratio (NPR) and nitrogen apparent digestibility coefficient (ADC). The NPR and nitrogen ADC values of rapeseed proteins did not change significantly (P<0.05) after hydrolysis but decreased significantly (P<0.05) after 30% and 70% acetylation. Acetylation (30%) followed by protein hydrolysis decreased significantly (P<0.05) the NPR value but increased significantly (P<0.05) the nitrogen digestibility compared to the control and unmodified rapeseed proteins. Casein gave the highest value (P<0.05) for NPR and nitrogen ADC. Modification of rapeseed proteins significantly (P<0.05) decreased the nutritive value, and the effect was more pronounced with increasing level of acetylation.     

Effect of methanol/acetone/water extraction and enzymatic hydrolysis on the nutritional value of unheated rapeseed proteins

The objective of this work was to study the effect of the extraction of phenols by methanol/acetone/water and proteolysis (pepsin 1 hour; trypsin 2 hours) on the nutritional characteristics of unheated rapeseed protein as measured by weight gain, protein intake, net protein ratio, apparent digestibility and absorbed protein. The effect of proteolysis of the methanol/acetone/water extracted rapeseed protein, and the effect of mixing the methanol/acetone/water extract back with the extracted rapeseed protein was also studied. Extraction of phenolic compounds from rapeseed flour significantly improved weight gain, protein intake, net protein ratio and absorbed protein value. However, the mixing of phenolic extract with the extracted rapeseed protein did not appear to have a significant effect.Enzymatic hydrolysis (1 hour with pepsin and 2 hours with trypsin) of the raw material significantly improved the weight gain and protein intake. The combined methanol/acetone/water extraction and protein hydrolysis treatments were beneficial on all nutritional quality parameters of rapeseed protein. These results suggest that the protein-bound phenolic compounds, rather than the free phenolic compounds contribute mainly to the decrease in the nutritional values of proteins associated with phenolic compounds in raw flour before extraction.     

Limitations of corn (Zea mays) and common bean (Phaseolus vulgaris) diets as protein and calorie sources

Mixtures of 70:30 and 87:13 of corn and beans with or without vitamins, minerals, limiting amino acids and calories were fed to 5-week-old pigs to determine performance and efficiency of utilization. After 12 weeks it was shown that increasing the ratio from 87:13 to 70:30 (corn:beans) was a desirable measure as was the simultaneous supplementation with the other nutrients; individual groups of nutrients resulted in partial improvement in animal performance. None of the diets used was capable of inducing growth similar to the control groups fed a corn:soya diet. Results confirm the importance of total nutrients to obtain increased efficiency of protein utilization; furthermore, diets, such as the corn:bean diets studied, need to be improved in relation to both quality and quantity of protein.INCAP Publication I-1144     

Chemical composition and protein quality of lentils (Lens) consumed in Egypt

Three local cultivars of lentil (Lens) seeds (Giza 9, Family 91, and Family 195) as well as one imported Pakistani variety were studied. Moisture, protein, fat, carbohydrate, ash, fiber, thiamine, riboflavin, amino acids and some protein fractions were determined on the unpeeled and peeled seeds. The protein quality was evaluated by determining the protein efficiency ratio, net protein utilization, biological value, and true digestibility coefficient. All components were increased by peeling, except the ash, the fiber content, and the residual nitrogen content of the insoluble protein fraction. The latter was markedly decreased by peeling. Giza 9 lentil seeds were found to contain the highest protein and thiamine contents. They showed the highest protein quality and proved to be nutritionally superior to other varieties. Generally, the three local cultivars were found to be chemically and biologically superior to the imported Pakistani cultivar.     

The nutritional quality of potato protein from intraspecific hybrids

The nutritional value of potato hybrids with Groups Andigena, Phureja, and Tuberosum parentage was measured by protein efficiency ratio (PER). Three diets at 6.0%, 7.75%, and 9.0% crude protein in potato flakes were fed to rats; 18 genotypes were analyzed and the hybrids had higher PER values than Group Tuberosum varieties, but increased tuber protein did not influence the PER values. The overall mean PER was 2.3, and 12 of the potato-flake diets were not different from the casein controls. Fortification with isoleucine did not improve the nutritional quality of the potato flakes. One diet was improved with the addition of both isoleucine and methionine. The influence of sulfur-containing amino acids in potato protein quality among these hybrids is not clear. It is suggested there may be two types of hybrids, one with dependence on these amino acids and a second type with a different protein factor(s) affecting the nutritional quality of the protein. Protein from these potato hybrids, as measured by PER, is among the highest in biological quality when compared with other proteins in plant foods.     

Protein Nutritional Quality of Infant Cereals during Processing

The most common food for weaning at the age of 4–6 months is cereal since is that it is a good source of high quality protein. However, processing may affect this quality. The aim of the present study was ascertain the changes that take place during four processing stages of infant cereals (in the raw materials, after roasting, after enzymatic treatment and drum drying, and in the commercial product), the following protein nutritional parameters: crude and true protein (CP and TP, respectively), in vitro protein digestibility (IVPD), free amino acids (FAA), calculated protein efficiency ratio (C-PER) and total amino acids profile. Of the infant cereals studied two contained gluten (‘Multicereal’ and ‘Wheat’) and two were gluten-free (‘Growth’ and ‘Rice and carrot’). All the parameters studied were affected by the different processing stages, but none showed a clear trend. The CP and TP content decreased after heat treatment (roasting) with a consequent increase in FAA content due to protein hydrolysis and the release of amino acids. IVPD remained stable during the processing stages in all the infant cereals, except in ‘Wheat’, while C-PER increased significantly. Infant cereals containing gluten showed higher CP and TP contents, and also higher IVPD than gluten free cereals, in which a digestibility value higher than 75% was reached. The overall content of essential amino acids, including sulphur amino acids, was acceptable (equal to or higher than FAO/WHO recommendations), although lysine (Lys) was the limiting amino acid in all the infant cereals.     

Nutritional characteristics of Cassava (Manihot esculenta Crantz) leaf protein concentrates obtained by ultrafiltration and acidic thermocoagulation

Some nutritional characteristics of cassava (Manihot esculenta) leaf protein concentrates obtained by ultrafiltration were compared with that obtained by acidic thermocoagulation. Protein concentrates did not show noticable differences in their proximal composition and amino acids content. However, higher values of total carotene, available lysine, and in vitro digestibility were found, in contrast with less content of total cyanide in protein concentrates obtained by ultrafiltration. Protein efficiency ratio (PER) values of the leaf protein concentrates obtained by ultrafiltration were higher than those obtained by thermocoagulation, 1.81 and 1.60 respectively. These values increased to 2.30 and 1.90 when the concentrates were mixed with sesame flour, in proportion according to the chemical score of their proteins.     

Characterization of seed storage proteins of urdbean (Vigna mungo)

Dehulled and defatted flour of urdbean (Vigna mungo), Var T-9, contained 25% protein with maximum contribution by globulins (63%). Albumins and glutelins contributed 12% and 21% respectively, whereas prolamins were present only in traces (1%). Globulins were further fractionated into legumin and vicilin type proteins which were present in the ratio of 4:1. All the protein fractions were heterogenous in nature as revealed by high performance liquid chromatography. SDS-polyacrylamide gel electrophoresis revealed the total protein sample to contain 21 different components with molecular weights ranging from 8.92 to 117.49kd. Albumins, globulins, prolamins and glutelins resolved into 4, 8, 6 and 13 different sized components of molecular weights ranging from 10.23 to 25.53, 10.84 to 112.72, 10.33 to 51.52 and 8.91 to 112.72kd, respectively. Amino acid analysis of all fractions revealed that glutamic acid was present in maximum concentration followed by aspartic acid and lysine. Just like other pulse proteins, the urdbean proteins were also deficient in sulphur containing amino acids.     

单仓高效平筛制备菜籽浓缩蛋白的研究

为了提高菜籽浓缩蛋白的生产效率以及蛋白含量，以预浸压榨菜籽粕为原料，研究单仓高效平筛制备菜籽浓缩蛋白的工艺。通过对原料的粒径分布以及不同粒径原料的成分分析得到原料粒径分布的R-R分布函数；对原料蛋白质与植酸的含量进行了相关性分析，结果显示两者具有显著的相关性（r=0.994 1）。利用单仓高效平筛制备菜籽浓缩蛋白，以筛下物得率和筛下物蛋白含量为指标研究进料流量和平筛旋转速度对筛分效果的影响，确定制备菜籽浓缩蛋白的最佳工艺为：进机流量为2kg/min，平筛回转速度为260r/min，在最优工艺条件下得到的菜籽浓缩蛋白的蛋白含量为56.99%(干基)，得率为26.66%，经醇洗脱毒后得到的菜籽浓缩蛋白的蛋白含量可达60.155%。     

Chemical composition and nutritional quality ofCleome dolichostyla seeds

Seeds ofCleome dolichostyla were analysed for proximate composition, mineral element contents and amino acid composition, in-vitro protein digestibility (IVPD) and calculated protein efficiency ratio (C-PER). The seeds (dry basis) were rich in oil (32.1%), protein (24.6%) and fiber (17.8%) content. The contents of various mineral elements mg/100 g) were: Ca=1970, P=493, Mg=127, Na=35, K=465, Fe=71.97, Zn=2.25, Cu=0.44 and Mn=1.45. Aspartic acid, glutamic acid, glycine, arginine and histidine were the major amino acids inC. dolichostyla seed protein accounting for half of the total amino acids. Lysine was the most limiting essential amino acid (FAO/WHO, 1973 reference pattern) with a chemical score of 45 for the protein. The IVPD of cleome seed protein was 72.2% and C-PER was 1.08 relative to the IVPD and C-PER values of 90.0% and 2.50 for the Animal Nutrition Research Council casein.     

Nutritive value of prickly pear seeds,Opuntia ficus-indica

Results are reported on the nutritional quality of prickly pear seeds,Opuntia ficus-indica. The seeds contained 16.6% protein, 17.2% fat, 49.6% fiber and 3.0% ash. The meal showed a high amount of iron (9.45 mg %). The contents of Mg, P, K, Zn and Cu were nutritionally significant contributing approximately 10–20% of the Recommended Dietary Allowances (RDA) of these elements per 100 g of dry weight. The amount of Ca represented less than 10% of the RDA for that element. Aspartic acid, glutamic acid, arginine and glycine were the most abundant amino acids making nearly half of the total amino acids content. The seeds were rich in sulfur amino acids (methionine + cystine). Lysine was the first limiting amino acid resulting in a chemical score of 62 for the protein. The in-vitro protein digestibility and the calculated protein efficiency ratio were 77% and 1.82 compared to 90% and 2.50, respectively, for ANRC casein.     

Chemical composition and nutritional potential of yam bean seeds (Pachyrhizus erosus L. Urban)

Pachyrhizus erosus seeds were analysed for proximate composition, minerals, protein fractions, antinutritional factors, and rotenoids. The seeds showed a high content of proteins, lipids, Fe and Ca, in comparison to other legumes. Glutelins constitute the highest protein fraction, followed by globulins. Antinutritional substances detected as tannins, hemagglutinating activity and trypsin inhibitory activity, were in low concentrations. Seeds were also processed to obtain a flour which showed proper characteristics, good in vitro digestibility, significant rotenoid reduction level and amino acid composition rich in essential amino acids, except methionine.     

Amino acid composition protein quality and water-soluble vitamin content of germinated cowpeas (Vigna unguiculata)

Amino acid composition, protein digestibility, calculated protein efficiency ratio (C-PER and DC-PER), chemical scores and water-soluble vitamin content of cowpea seeds germinated at 25°C or 30°C for 24h were determined. Also, the effect of processing steps (heated-air drying, decortication and cooking) on these parameters were examined. Germination had little effect on amino acid profile of cowpeas. In vitro protein digestibility was not improved significantly by germination nor by decortication but was improved by cooking. C-PER and DC-PER ranged from 1.95 to 2.21 and from 1.63 to 1.82, respectively. DC-PER compared well withreported rat PER of cowpea products and seemed more sensitive than C-PER. Based on whole egg values, chemical scores ranged from 37.7 to 45.8% (mean±SD; 42.2±2.4%). Germination increased the contents of niacin, thiamin and riboflavin significantly. Decortication resulted in up to 30% loss in niacin while thiamin content was reduced 41% by cooking.