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1.
Tryptophan bioavailabilities were estimated in 16 protein sources using 10 day rat growth assays with casein as the reference protein. Growth responses of rats fed test food diets were compared to growth responses of rats fed basal diets with graded levels of tryptophan ranging from 50 to 100 mg of tryptophan/100 g diet. Estimates of tryptophan availabilities were 85–100% for all products except whole wheat cereal (73%) and pinto beans (59%). Results of a previous study on lysine availability indicated that poor response to pinto beans was due either to poor digestibility or to the presence of some unidentified growth inhibitor.  相似文献   

2.
Methionine availabilities of 16 test proteins were assessed by comparing ten day rat growth response to the test diets and reference (casein) diets. In a preliminary study, various concentrations of methionine and cystine were fed to determine methionine requirements and effect of excess cystine. Results indicated a methionine requirement of about 550 mg per 100 g diet. Cystine had a sparing affect of 50–55%, i.e., about 300 mg could be used to meet methionine requirements. Further additions of cystine (up to 2.6 times methionine) did not affect rat growth. Methionine availabilities were excellent (88–100%) for 15 of the 16 test foods; only pinto beans (58%) were low, but prior evidence indicates that the poor growth response was due to some factor other than availability.  相似文献   

3.
The commercial oil cake produced during expeller pressing of maize germ, was extracted with n-hexane and 80 percent ethanol followed by seiving to remove undesirable materials. In defatted maize germ oil cake (DMGOC): protein, starch, fat, crude fiber (CF) and ash were respectively 24.69, 36.55, 5.68, 7.56 and 3.90 percent and they decrease after processing except ash, which increased slightly. It contains better quality protein having only 3 percent zein and 47 percent albumin. Its amino acids like lysine and tryptophan and biological value (BV) were higher than that of whole maize grain, and was comparable with that of the amino acid requirement of preschool children and casein diets both. Its digestible energy (DE) was lower compared with whole maize grain as well as the casein diets. After processing albumin, globulin and zein decreased whereas glutelin and the residual fraction increased. Not much differences were observed in chemical composition and different amino acids, in vitro protein digestibility (IVPD), true digestibility (TD), BV and DE improved after processing.  相似文献   

4.
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.  相似文献   

5.
The powder forms of soy-based infant formulas obtained from four manufacturers were fed to weanling rats for two weeks, as the sole source of protein in diets containing 8% protein, 20% fat, and adequate amounts of minerals and vitamins. The relative protein efficiency ratio (RPER) and the relative net protein ratio (RNPR) values (casein + methionine=100) of diets containing unsupplemented formulas were 71–81 and 78–85, respectively. Supplementation of the formula diets with lysine (0.2%), methionine (0.2%), threonine (0.1%) or tryptophan (0.05%) increased the level of the supplemental amino acid in rat serum but generally failed to improve the RPER or RNPR values. Addition of all four essential amino acids to the formula diets, however, caused a marked improvement in their protein quality (RPER or RNPR values=100). The data suggested that proteins in soy-based formulas could be marginally co-limiting in several indispensable amino acids.Presented in part at the 202nd annual meeting of the American Chemical Society, New York City, 25–30 August 1991.  相似文献   

6.
Based on the nitrogen balance (NB) data and the efficiency of amino acid utilization, optimum supplements of limiting amino acids (AA) to triticale were calculated and their effect on true N digestibility (TD), biological value of protein (BV) and net protein utilization (NPU) of a triticale-based diet was evaluated. To determine if AA balance must be considered in the calculation of the optimum supplements, the effect of a 20% of 40% excess of essential AA in lysine-, methionine-, threonine- or tryptophan-deficient diets was also studied. The AA excess had no significant effect on NB in diets deficient in lysine, methionine or threonine. However, NB in rats fed on the tryptophan-deficient diet increased as the AA excess increased. BV of the diet containing the optimized supplements of lysine, threonine, methionine and valine was comparable to that of lactalbumin or to the diet supplemented with all essential AA. The deletion of valine from the optimized supplement caused an insignificant decrease in BV. Due to the lower TD, NPU of diets containing the optimized AA supplements was lower than that of the diet containing all essential AA or of the lactalbumin-based diet.  相似文献   

7.
Weanling male Wistar rats were fed 20% protein diets based on casein or either of two combinations of soy protein isolate and ground raw soy providing three levels of soybean trypsin inhibitors (SBTI; 0,448 and 808 mg of trypsin inhibited per 100g of diet respectively). DL-ethionine was included at three levels (0,0.05% and 0.10%) with each level of SBTI. After 4, 8 and 12 weeks ofad libitum feeding, diets containing SBTI without DL-ethionine were associated with decreases in weight gain, feed efficiency, serum cholesterol and serum urea nitrogen. Higher levels of triglycerides, glutamate pyruvate transaminase (SGPT) and altered serum free amino acid levels were also found. Increased dietary levels of DL-ethionine also resulted in deficits in growth and feed efficiency, decreased serum cholesterol, increased SGPT and similar alterations in serum free amino acids. Combination of dietary SBTI with DL-ethionine resulted in even greater growth deficits and serum cholesterol decreases as well as increases in SGPT and serum triglycerides and changes in serum free amino acid levels. Methionine deficiency in the young rats fed SBTI and DL-ethionine was indicated by the changes in serum amino acids and growth deficits. Moderation of some effects over the 12 week test period suggested decreased methionine requirements in the older rats.  相似文献   

8.
Two varieties of mesta (Hibiscus sabdariffa) seeds were analysed for their proximate composition. Their protein (18.8–22.3%), fat (19.1–22.8%) and dietary fiber (39.5–42.6%) contents were found to be high. The seeds were found to be a good source of minerals like phosphorus, magnesium and calcium. Their lysine and tryptophan contents were also high. Sulphur containing amino acids were limiting in this seed protein and the chemical score of mesta seed protein was 40 and 57 for AMV-2 and Bhimili-1 varieties respectively. Mesta seed oil is rich in unsaturated fatty acids (70%), of which linoleic acid constituted 44%. Weanling rats were fed with 10% mesta seed protein before and after cooking for 4 weeks. Food intake of animals receiving raw mesta seed diets was significantly lower than those receiving cooked mesta seed diets as well as the casein control diet. Protein and dry matter digestibilities of raw and cooked mesta seed diets were lower than that of casein control diet. Cooking improved the food intake, gain in body weight, dry matter and protein digestibility of mesta seed diets. PER and NPU of cooked mesta seed diets were significantly higher than the corresponding raw diets. These results indicate that cooked mesta seed protein is of relatively good quality.  相似文献   

9.
The digestibility of proteins and individual amino acids of nineteen selected foods was determined by anin vitro assay. Samples were hydrolysed with pepsin for 30 minutes in an acidic medium; the pH was then raised to 7.5 and the mixture poured into the dialysis bag (molecular weight cut-off 1000) of a digestion cell with pancreatin. Digestion products, mixtures of free amino acids and low molecular weight peptides which pass through the dialysis membrane, were collected for 6 hours by sodium phosphate buffer circulation. All proteins from animal sources displayed a digestibility similar to casein, except for breakfast sausage. Vegetable proteins showed intermediate digestibility, except for cereals (lower) or peanut butter (higher). Target amino acids of enzymes were generally more readily hydrolysed. However, compared to other animal proteins, glycine in milk products, valine, isoleucine, methionine and lysine in breakfast sausage and hot dog, and histidine in tuna were more easily released. Overheating of non-fat dried milk not only reduced the lysine digestibility, but also that of methionine, phenylalanine, histidine and cystine. Among vegetable proteins, wheat products were characterized by a relatively greater release of threonine, isoleucine and histidine, and peas by a lower digestibility of methionine and lysine. Proline of soy isolate and isoleucine of pinto bean were resistant to hydrolysis while arginine of pinto beans and of rice-wheat-gluten was easily released.  相似文献   

10.
The protein quality of high lysine barley genotypes Notch1 Notch2,Riso-1508 and Hiproly grown in Indian soil was evaluated by determining amino acid composition and also by rat growth and nitrogen balance studies. Protein and fat contents were found to be highest in Riso-1508. Lysine concentration (5.26 g/16g N) of Riso-1508 was also highest compared to the other high lysine genotypes. Rat feeding trials indicated that the growth promoting qualities of the proteins of genotype Riso-1508 were significantly (p < 0.05) higher than the low lysine barley genotype. The comparatively low lysine barley diet had more digestible protein than the high lysine barley diet. However, the BV and NPU of the high lysine barley were significantly (p < 0.05) higher. This improvement is of importance in meeting the essential amino acid requirements of man as well as other monogastric animals. The study showed that the high lysine barley harvested in Indian agroclimatic conditions retained high lysine quality.  相似文献   

11.
Two experiments are reported. In the first experiment the amino acid compositions of rumen bacteria and protozoa isolated from sheep given a diet of grass silage were compared with those taken from sheep given a diet of hay and barley; four sheep were assigned to each diet. There were no significant differences (P<0·05) between diets in the amino acid compositions of the microbial fractions and bacterial contents of α-ɛ-diaminopimelic acid were also similar for both diets.
In the second experiment the digestion of a grass silage and barley diet (65:35; 135 g CP (kg DM)-1) was studied using four non-lactating Ayrshire cows fitted with cannulae in the rumen and in the proximal duodenum. The mean N intake was 154 g d-1 and the corresponding duodenal flow was 126 ± 10 g d-1 indicating that 0·21±0·07 of the N intake was absorbed between the mouth and the duodenum. The mean rumen NH3-N concentration was high, 297 g litre-1, and the mean rate of microbial protein synthesis in the rumen was low, 17 g microbial N (kg OM apparently digested in the rumen)-1. There was a low content of bacterial N in the non-ammonia N at the duodenum (mean proportion 0·52±005) and low concentrations of methionine and lysine in the duodenal digesta protein. The results are discussed in relation to previously published data on the digestion of silage diets in sheep and to the utilization of silage diets for milk production in the cow.
It is concluded that with silage diets the supply of methionine and lysine to the duodenum is likely to be low because of the low rates of microbial protein synthesis in the rumen and that in cows those two amino acids may be limiting for milk production.  相似文献   

12.
A basal diet (containing 20% soybean protein isolate) was supplemented with limiting amino acids (AA, methionine, threonine and tryptophan); wheat bran (WB, 24.3%); amylose (AM, 10%) or a combination of AA and WB or AM to investigate their effects on the levels of blood serum urea nitrogen (BUN), other blood parameters, growth and fecal characteristics in young rats. After 3 weeks feeding, supplementation of the basal diet with AA or WB resulted in improved growth (gain/food ratio) while the addition of AM had no effect on rat growth. Addition of WB to the basal diet had no effect on BUN while the addition of AA and AM caused about 20 and 12% reduction in BUN values, respectively. Rats fed the AA-AM diet had the lowest BUN values (42% lower than those fed the basal diet). Fresh volume, fresh weight, moisture and dry weight of feces in rats fed the WB diets were about four to five fold higher than in those fed the AM diets. The results suggested that BUN may not be a good predictor of growth and protein quality in diets containing AM or a source of dietary fiber (WB).  相似文献   

13.
Nitrogen balance experiments were conducted on growing rats to study the sequence of limitation of amino acids in triticale protein. All essential amino acids were added to a triticale-based diet to adjust their total dietary levels to 110% of the requirement. From this complete supplement, individual amino acids were successively removed and nitrogen balance (NB) and biological value of protein (BV) were measured. Based on the extent of response to removal of amino acids, the sequence of limitation was estimated to be lysine, threonine, methionine and valine. The removal of histidine, isoleucine or tryptophan had no effect on NB or BV.  相似文献   

14.
Nitrogen balance experiments were conducted on growing rats to study the sequence of limitation of amino acids in triticale protein. All essential amino acids were added to a triticale-based diet to adjust their total dietary levels to 110% of the requirement. From this complete supplement, individual amino acids were successively removed and nitrogen balance (NB) and biological value of protein (BV) were measured. Based on the extent of response to removal of amino acids, the sequence of limitation was determined to be lysine, threonine, methionine and valine. The removal of histidine, isoleucine or tryptophan had no effect on NB or BV.  相似文献   

15.
Potential use of the high protein by-product of beer production from 77% sorghum malt and 23% maize grit was investigated. Red sorghum spent grains (RSSG) and white sorghum spent grains (WSSG) contained 23.4 and 19.3% crude protein (CP), 54 and 43% dietary fiber (NDF), 1.44 and 0.78% ash, 4.5 and 3.2% hexane extract and tannin content of 7.5 and 1.0 mg/g catechin equivalent respectively. Magnesium was the most abundant mineral in both RSSG and WSSG — 185 and 140 mg/kg, respectively. Calcium, zinc, iron and copper were generally low. Both samples contained cadmium 1.12 (WSSG), 1.19 (RSSG) and lead at 1.38 mg/kg. Lysine was the limiting amino acid (chemical score 0.55) in both samples. Other essential amino acids were adequate or surplus. Stearic acid was the predominant fatty acid with varying levels of lauric, myristic, palmitic, and oleic acids in both samples. Feed intake and weight gain were highest in rats fed 26.3% WSSG (contributing 50% of the diet protein) but protein efficiency ratio (PER) and net protein retention (NPR) were highest in diets where spent grains contributed just 25% of the diet protein. True digestibility of diets decreased as dietary fiber content increased such that animals on diets containing 100% spent grain protein (above 20% NDF) lost weight.  相似文献   

16.
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.  相似文献   

17.
Nutrient content of the edible leaves of seven wild plants from Niger   总被引：1，自引：0，他引：1  
Wild plants play an important role in the diet of the inhabitants of Niger. These plants tend to be drought-resistant and are gathered both in times of plenty as well as times of need. Used in everyday cooking, famine foods may be an important source of nutrients. The goal of this study was to investigate the nutritional role of wild plants in the nigérien diet. To this end, leaves of seven plants species were analyzed for their mineral, amino acid and fatty acid contents: Ximenia americana, Amaranthus viridus, Corchorus tridens, Hibiscus sabdarifa, Maerua crassifolia, Moringa oleifera, and Leptadenia hastata. Ximenia americana} contained large amounts of calcium. Large quantities of iron were present in Amaranthus viridus. All seven plants contained significant amounts of selenium and phosphorus. Corchorus tridens contained the most protein (19–25% dry weight), and its composition compared favorably to the World Health Organization's standard for essential amino acids. Moringa oleifera contained 17% protein and compared favorably with the WHO standard. Corchorus tridens contained the largest amounts of the two essential fatty acids linoleic and -linolenic acids. These results reinforce the growing awareness that wild edible plants of the Western Sahel can contribute useful amounts of essential nutrients, including amino acids, fatty acids and trace minerals, to human diets.  相似文献   

18.
Three marketing varieties of almonds; Carmel, Mission, and Nonpareil; were analyzed for proximate composition and protein nutritive quality. Moisture, lipids, protein, ash, sugars, and tannins ranges were 3.05-4.33%, 43.37-47.50%, 20.68-23.30%, 3.74-4.56%, 5.35-7.45%, and 0.12-0.18%, respectively. No detectable hemagglutinating and trypsin inhibitory activities were present in Carmel, Mission, and Nonpareil almonds. Amino acid analyses indicated the sulfur amino acids (methionine + cysteine), lysine, and threonine to be the first, second, and third limiting amino acids in almonds when compared to the recommended amino acid pattern for children 2-5-year old. However, compared to the recommended amino acid pattern for adults, sulfur amino acids were the only limiting amino acids in almonds tested. True Protein Digestibility (% TPD) values for Carmel, Mission, and Nonpareil were 88.55 +/- 1.26, 92.25 +/- 1.05, and 82.62 +/- 1.47, respectively. Protein Digestibility Corrected Amino Acid Scoring (PDCAAS) values suggested almond proteins to be of poor nutritional quality.  相似文献   

19.
A 16-week feeding test of Tower (Brassica napus) and Span (Brassica campestris) rapeseed protein concentrates (RPC) was carried out on male and female Charles River CD (Sprague-Dawley) weanling rats. The diets contained 10% or 20% protein (N × 6.25) from each RPC and were supplemented with 150 mg zinc/kg. The control groups received a purified diet with casein or a laboratory chow diet. The results of the test diet groups did not reveal any adverse effect due to RPC on thyroid metabolism or the metabolism of zinc iron, copper, manganese, calcium, phosphorus, and magnesium. Nephrocalcinosis was observed in all female rats that were fed the test diets and the casein control diet, and therefore it could not be attributed to dietary RPC.Bureau of Nutritional Sciences, no. 120. Food Research Institute, no. 448.  相似文献   

20.
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.  相似文献   

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