Reactions of chlorogenic acid and quercetin with a soy protein isolate--influence on the in vivo food protein quality in rats

Plant phenolic compounds are known to interact with proteins producing changes in the food (e. g., biological value (BV), color, taste). Therefore, the in vivo relevance, especially, of covalent phenol-protein reactions on protein quality was studied in a rat bioassay. The rats were fed protein derivatives at a 10% protein level. Soy proteins were derivatized with chlorogenic acid and quercetin (derivatization levels: 0.056 and 0.28 mmol phenolic compound/gram protein). Analysis of nitrogen in diets, urine, and fecal samples as well as the distribution of amino acids were determined. Depending on the degree of derivatization, the rats fed with soy-protein derivatives showed an increased excretion of fecal and urinary nitrogen. As a result, true nitrogen digestibility, BV, and net protein utilization were adversely affected. Protein digestibility corrected amino acid score was decreased for lysine, tryptophan, and sulfur containing amino acids.     

Gross and true ileal digestible amino acid contents of several animal body proteins and their hydrolysates

Amino acid compositions of ovine muscle, ovine myofibrillar protein, ovine spleen, ovine liver, bovine blood plasma, bovine blood globulins and bovine serum albumin and the amino acid compositions and in vivo (laboratory rat) true ileal amino acid digestibilities of hydrolysates (sequential hydrolysis with Neutrase, Alcalase and Flavourzyme) of these protein sources were determined. True ileal amino acid digestibility differed (P < 0.05) among the seven protein hydrolysates. The ovine myofibrillar protein and liver hydrolysates were the most digestible, with a mean true ileal digestibility across all amino acids of 99%. The least digestible protein hydrolysate was bovine serum albumin with a comparable mean true ileal digestibility of 93%. When the digestible amino acid contents were expressed as proportions relative to lysine, considerable differences, across the diverse protein sources, were found in the pattern of predicted absorbed amino acids.     

Study of the effect of using different levels of tahinah (sesame butter) on the protein digestibility‐corrected amino acid score (PDCAAS) of chickpea dip

This study was conducted to investigate the effect of using different proportions of tahinah (0–25%) on the protein digestibility‐corrected amino acid score (PDCAAS) of chickpea dip and to evaluate this parameter when chickpea dip is consumed with wheat bread. Protein quality was evaluated using the methods of amino acid score and true protein digestibility in weanling Sprague–Dawley rats. The levels of tahinah that provided the best true protein digestibility and protein digestibility‐corrected amino acid score were 20 and 25%. Values of true protein digestibility were significantly higher (P ≤ 0.05) than for the other types of chickpea dip (0.87 and 0.88 respectively). The consumption of wheat bread with chickpea dip led to a marked improvement in the true protein digestibility of the protein mixture (0.90); however, the protein digestibility‐corrected amino acid score did not change in the same manner owing to the relatively low amino acid score. It can be concluded that the addition of tahinah to chickpea led to an increase in the protein digestibility‐corrected amino acid score of chickpea dip (based on laboratory rat requirements for essential amino acids) and that the consumption of chickpea dip with bread led to an improvement in the protein digestibility of chickpea dip but not in the protein digestibility‐corrected amino acid score. © 2002 Society of Chemical Industry     

Amino acid digestibility of protein concentrates given separately or together with cereal grains

In experiments with rats the amino acid digestibility of three protein concntrates (soya bean meal, herring meal, horse bean meal) was measured when these protein sources were given separately and together with cereal grains (barley, maize, oats or wheat). True digestibility of the individual amino acid components was in general close to the digestibility of the corresponding protein source. Furthermore it was found that the true digestibility of amino acids in a feed mixture is directly related to the amino acid digestibility of the individual protein components in the diets.     

Nutritive value of potato crude protein as influenced by manuring and amino acid composition.

Potatoes were grown in pots and fertilised with varying amounts of nitrogen (as nitrate or ammonium sulphate or urea), phosphorus, potassium and cow manure. The largest yield, 451 g DM per pot, was obtained with nitrogen in the form of urea. N-applications and P- and K-deficiency in the soil increased the total-N content, which varied from 1.14–3.07%. Concentrations of nitrate-N (0.001–0.016%) were negligible. Increasing N-concentrations were associated with decreases in the crude protein of most amino acids including lysine (6.26–4.17%), threonine (4.08–2.90%), methionine (1.98–1.46%) and tryptophan (1.74–0.86%). The concentrations of aspartic and glutamic acids (probably mainly present as their amides) increased. Differences in amino acid composition between boiled and unboiled potatoes were negligible. From 70 to 90% of the decrease in concentration of most essential amino acids could be accounted for by changes in N-content of dry matter. Phosphorus and potassium affected the amino acid composition indirectly through their effects on N-content. In rat feeding experiments increasing N-concentrations in potatoes increased the true digestibility of the crude protein from 79 to 91 but decreased the biological value from 82 to 59. The net protein utilisation did also decrease (from 67 to 54). These relationships were linear below 2.2% N in dry matter. Changes were mainly dependent on variations in N-content. Decreases in essential amino acid indices or chemical scores were closely reflected in the results of the feeding experiments. The true amino acid digestibilities were different for individual amino acids and increased with increasing N-concentration in dry matter.     

High apparent ileal digestibility of amino acids in raw and germinated faba bean (Vicia faba)‐ and chickpea (Cicer arietinum)‐based diets for rats

The effects of germinated faba bean (Vicia faba minor var Alameda)‐ and chickpea (Cicer arietinum kabuli var Athenas)‐based diets on performance, N utilisation, amino acid ileal digestibility and plasma concentrations were studied in growing male Wistar rats. Raw and germinated faba bean and chickpea seed meals were incorporated in essential amino acid‐supplemented and energy‐equalised diets as the only sources of protein. A lactalbumin‐based diet equalised in protein (100 g kg^?1) and digestible energy (15.5 kJ g^?1) with the test diets was used as control. Weight gains, gain/feed ratios, N retention and NPU values of animals fed raw or germinated legumes were lower than those of rats given the control (lactalbumin) diet, while faecal dry weights were higher. However, N retention and NPU values of rats fed germinated faba bean diets were higher and faecal dry weights lower than those of animals fed non‐germinated faba bean diets. Liver and thymus fresh and dry relative weights were lower than controls for all legume diets, whilst small intestine, caecum and colon relative weights were higher than controls for non‐germinated faba beans and chickpeas either germinated or not. Caecum and colon fresh and dry relative weights of rats fed germinated faba bean seeds were lower than those of rats fed non‐germinated faba beans and not different from controls. Except for aspartic acid and proline in rats fed raw faba bean diets, apparent ileal digestibilities of amino acids were not different or higher in rats fed legume diets as compared with controls. Except for arginine, apparent ileal amino acid digestibility was higher for germinated than for non‐germinated faba bean seeds. The amounts of glycine, arginine and ornithine in plasma significantly increased whilst those of threonine, alanine, leucine and lysine decreased with respect to controls in faba bean‐ or chickpea‐fed rats, either germinated or not. We conclude that (a) germination of faba bean seeds gave rise to a significant (P < 0.01) but limited improvement in performance, N retention and apparent ileal digestibilities of some amino acids in growing rats compared with non‐germinated seeds, while there was no detectable effect in the case of germinated chickpea seeds, and (b) the apparent ileal amino acid digestibility of essential amino acid‐supplemented diets based on faba bean or chickpea meals, either germinated or not, is similar or even higher than controls. © 2002 Society of Chemical Industry     

The protein and the amino acid composition of some rice and maize varieties grown in North Vietnam

The protein and amino acid composition of several rice and maize varieties grown in North Vietnam, and their digestibility, was determined. The protein content (N×5.95) of rice cultivars ranged from 7.0 to 10.8% of which 70–80% was in the glutelin fraction. The true digestibility was relatively good (87.6–91.8%). In general, lysine and threonine were found to be the first and second nutritionally limiting amino acids, except for two varieties, which had a low content of sulphur-containing amino acids. The protein content of maize cultivars ranged from 8.4 to 12.9%. Zein and glutelin were the main components occurring in near-equal quantities (except in the opaque-2 mutant). The overall amino acid distribution was similar to that of maize grown in other countries. Lysine levels were relatively low, and it was the first nutritionally limiting amino acid, except in the opaque-2 cultivar, tryptophan being the second one. The digestibility ranged from 87.5 to 91.1%.     

Total and ileal digestible tryptophan contents of feedstuffs for broiler chickens

Reliable values of total and digestible tryptophan in components of feed formulation matrices are needed because tryptophan is often the third limiting amino acid in practical poultry diets. However, tryptophan is oxidatively destroyed during acid hydrolysis in routine amino acid analysis and its determination requires a separate analytical procedure. The variability in contents and apparent ileal digestibility for 6‐week‐old broiler chickens of tryptophan in 74 samples representing 24 feedstuffs are presented in this paper. The average ileal tryptophan digestibility coefficient in wheat was 0.83, in sorghum and triticale 0.75, maize 0.71, soybean meal 0.84, sunflower meal 0.81, canola meal 0.78 and cottonseed meal 0.75. Among the grain legumes, tryptophan in lupins was better digested than that in chickpeas, fababeans and field peas. Among the animal protein meals, the tryptophan digestibility coefficients in fish meal (0.77) and blood meal (0.84) were substantially higher than those in meat meal (0.62), meat‐and‐bone meal (0.63) and feather meal (0.52). Marked variations in tryptophan digestibility were also observed among samples of fish meal, meat‐and‐bone meal and meat meal, highlighting significant batch‐to‐batch differences. For most feedstuffs, considerable variability was observed in the tryptophan concentrations, but such variations were not reflected in digestibility coefficients. Copyright © 2006 Society of Chemical Industry     

Digestive utilisation of protein and amino acids from raw and heated lentils by growing rats

The effect of autoclave treatment on the digestive utilisation of protein and amino acids from lentils was studied in growing rats. Twenty 3‐week‐old Wistar rats (mean live weight 59 ± 4.8 g) were fed two experimental diets (n = 10 rats per diet) consisting of raw lentils (Lens culinaris M, var vulgaris, cv magda‐20) (diet RL) or lentils autoclaved at 120 °C and 1 atm for 30 min (diet AL). An additional group of 10 animals was fed a low‐protein (4%) diet and used to estimate metabolic nitrogen and amino acid excretion. Autoclaving caused a 76% reduction in the levels of trypsin inhibitor activity, but failed to improve the faecal digestive utilisation of protein or total amino acids. Lowest essential amino acid true digestibility in diets RL and AL was found for cysteine (60.2 vs 60.1%) and methionine (68.9 vs 66.6%). The protein digestibility‐corrected amino acid score was 71.2 and 66.4% and the availability of sulphur amino acid‐corrected amino acid score was 57.1 and 52.1% for diets RL and AL respectively. Sulphur amino acids were the first limiting ones. Overall, autoclave treatment did not improve protein or total amino acid digestibility from lentils, but caused a significant improvement in leucine and lysine digestibility and a significant decrease in the digestive utilisation of tyrosine and methionine. © 2002 Society of Chemical Industry     

Composition and nutritive value of cormels of Colocasia esculenta (L.) Schott

The nutritional quality of the cormels of Colocasia esculenta (L.) Schott cultivar ‘Guavir’ was determined chemically and biologically in feeding experiments with weanling rats. The contents of starch and unavailable carbohydrates (cellulose, hemicellulose and pectin) were 54 and 15% of the dry matter respectively. Lipid accounted for less than 1% of the dry matter. Palmitic, oleic and linoleic acids were the main fatty acids in the lipids, with linoleic acid predominating. The content and fatty acid composition of the individual lipids was examined. Crude protein amounted to 10.4% of the dry matter. This protein was low in the sulphurcontaining amino acids and tryptophan, but contained adequate levels of the other essential amino acids. Diets containing raw cormel meal gave severely depressed net protein utilisation (NPU) and total nitrogen and carbohydrate digestibility when fed ad libitum to weanling rats. Both NPU and nitrogen and carbohydrate digestibility improved when the cormel meal was cooked prior to inclusion in the diets but such diets still did not support growth in weanling rats.     

Influence of thermoplastic extrusion on the nutritive value of bovine rumen protein

This study investigated the impact of thermoplastic extrusion on the nutritive quality of bovine rumen protein. Proximal composition, amino acid profile and in vivo true protein digestibility among rats were determined in raw (RBR) and extruded (EBR) rumen. Raw and extruded bovine rumen presented high percentages of protein (more than 95% on dry basis). Neither raw nor extruded proteins had any limiting amino acid, and the RBR and EBR amino acid scores were, respectively, 1.28 (leucine) and 1.25 (methionine plus cystine). Extrusion reduced significantly true protein digestibility from 97.7% to 93.1% (p < 0.001), but protein digestibility-corrected amino acid scores for both proteins (RBR and EBR) were 100%. Animal growth presented comparable profiles using raw and extruded rumen. In conclusion, thermoplastic extrusion did not affect the protein quality of bovine rumen, and this does not hinder the use of this material as a food ingredient.     

Compositional and nutritional studies on edible wild mushroom from northeast India

Two species of mushrooms Schizophyllum commune and Lentinus edodes from Northeast India were assessed for their nutritive value. Protein contents of S. commune (16%) and L. edodes (23%) were high, but fat content was low (2%) in both the mushrooms. Oleic and linoleic acids accounted for 72–77% of the total fat in both the mushrooms. Essential amino acid contents of S. commune and L. edodes were 34% and 39%, respectively. The chemical scores of S. commune (28) and L. edodes (29) were low compared to whole egg protein. Methionine was the limiting amino acid in both the mushrooms. Protein quality evaluation by NPR (net protein ratio), NPU (net protein utilization) and TDP (true digestibility of protein), showed that the mushrooms were comparatively much lower then casein in all the parameters examined. Animals on L. edodes showed significantly (p < 0.05) higher NPR, RNPR, and NPU than animals on the S. commune diet. True protein digestibility of the L. edodes diet was also significantly (p < 0.05) higher than the S. commune diet.     

AMINO ACID COMPOSITION AND IN VITRO PROTEIN DIGESTIBILITY OF DRIED SQUID REHYDRATED IN WATER AND ALKALI

Crude protein content, amino acid composition and in vitro protein digestibility of fresh, dried and rehydrated Argentina squid (Illex argentinus) were studied. Most of the nonamino acid nitrogenous compounds in the mantle muscle dissolved in water during rehydration. Rehydration improved the nutritive value of protein in dried squid. Rehydration decreased the concentration of proline relative to total amino acids in muscle. Aromatic amino acids were limiting essential amino acids in fresh and dried squid but not in rehydrated squid. Amino acid scores increased with the extent of rehydration, more so in alkali than in water. The alkali rehydration also increased the in vitro protein digestibility of dried squid.     

In Vivo Digestibility of Insoluble Collagen from Bovine Tendon as Influenced by the Inhibition of Gastric Acid Secretion

Insoluble collagen (bovine Achilles tendon), gelatin and meat were each mixed with whole egg protein (about 50% of the nitrogen) and fed to rats. True digestibility was evaluated after inhibiting gastric acid secretion with omeprazole. Insoluble collagen, supplemented with small amounts of essential amino acids, was also given but without inhibiting gastric acid secretion. Egg protein was fully digested and not affected by inhibition. The true digestibility of insoluble collagen/egg was 85%, corresponding to 71% true digestibility for insoluble collagen alone. This was significantly lower than the value of 95% obtained for insoluble collagen without inhibiting gastric acid secretion. True digestibilities for gelatin/egg were 99% and meat/egg 98%. Inhibition of gastric acid secretion thus did not affect digestion of gelatin and meat.     

Utilization of protein and energy from cooked maize: legume dishes in growing rats compared with a traditional Nigerian dish

Four dishes were prepared from cooked maize and legumes with a 2:1 maize:legume N ratio using soyabeans (MS), cowpea (MC), bambara groundnut (MB), with groundnut (MG), a popular Nigerian dish, taken as standard.
The protein contents of all three dishes were slightly greater than the groundnut dish with a higher content of lysine, the limiting amino acid in each instance. However the total energy contents were lower, 17.7 MJ Kg^-1 (MC), 18.3 (MS), and 17.5 (MB) compared with 20.0 (MG). In growing rats, there were no significant differences in biological values (BV) nor true N digestibility (TND) but net protein utilization (NPU) (BV multiplied by TDN) was lower, for MB than for the three other dishes.
Although the calculated protein scores, derived from the limiting amino acid lysine, did not parallel the bioassay, both indicated that all three dishes were equal or superior to the groundnut dish. These results suggest that the popular Nigerian maize-groundnut dish could be replaced by any of the other three dishes without loss of nutritional value, indeed the soyabean dish may even be of higher nutritional value.     

Nutritional quality of important food legumes

The proximate composition, mineral constituents and amino acid profile of four important legumes (chickpea, lentil, cowpea and green pea) were studied in order to evaluate their nutritional performance. Significant (P < 0.05) variations existed among the legumes with respect to their proximate composition, mineral constituent and amino acid profile. Lentil was found to be a good source of protein, while cowpea was good in ash among the grain legumes tested. All four types of legumes were also better suppliers of mineral matter, particularly potassium, phosphorus, calcium, copper, iron, and zinc. However, the concentrations of various mineral constituents was not in good nutritional balance. It was concluded that the four legumes tested were rich in lysine, leucine and arginine and can fulfil the essential amino acid requirement of human diet except for S-containing amino acids and tryptophan. In order to make good, the deficiency of certain essential amino acids in legume protein, they must be supplemented with other vegetables, meat and dairy products (e.g., Whey, yogurt).     

Evaluation of the nutritive value of plant protein concentrates

The nutritive value of acid and steam precipitated plant proteins extracted at pH 11 and acid precipitated plant proteins extracted at pH 8–11 were estimated. Acid precipitation was found to result in a higher true protein digestibility, biological value, net protein utilisation and protein efficiency ratio in rats and to be more completely hydrolysed in vitro than steam precipitated proteins. Proteins extracted from leaves at pH 11 were superior, for the same nutritive characteristics, to proteins extracted at lower pH (8–10) values. These differences are discussed in terms of differences in the quantities of certain amino acids present in the proteins, structural changes in the proteins and protein-carbohydrate interactions.     

Nutritive value of barley rootlets,a by-product of malting

The nutrient contents as well as the amino acid pattern of the rootlets by-product were determined. The analysis showed that at least 19 amino acids were present of which threonine and tryptophan were found in variable amounts. The net protein utilisation of the rootlets and proteolan by-products and mixtures of both were determined. The results indicate that the rootlets succeeded in supporting normal growth of the rats fed this by-product. The values for digestibility, biological value and net protein utilisation for the diets prepared by mixing the rootlets and proteolan in equal proportion were found to be 86, 67.9 and 59% respectively.     

Amino acid composition of storage proteins of a promising chickpea (Cicer arietinum L) cultivar

The amino acid compositions of flours made from the cotyledons and from the whole seeds of a disease-resistant, stable and high-yielding cultivar of chickpea (Cicer arietinum L) cv H75–35, known locally as Gaurav, have been analysed. These, together with similar analyses of the albumin, globulin, legumin and vicilin protein fractions, have been compared with those of other legumes. Seed protein content was 19·8 % with globulin constituting 62·4 % of the total seed protein. The ratios of albumin to globulin and legumin to vicilin were 1:4 and 6:1, respectively. The proportion of basic amino acids in the albumin was low whereas the reverse was true in the globulin. The legumin fraction seems to be superior in terms of total essential amino acids to those from other sources. Sulphur amino acids were the most limiting, followed by tryptophan or threonine depending on the fraction. However, the ratio of methionine to cystine was high (2·76:1). The extent of the sulphur amino acid deficiency was assessed, and possible approaches for its improvement are outlined.     

Synergistic effect of different pulses on the protein quality of rice

The protein quality of common Indian pulses, namely soybean (Glycine max), red gram (Cajanus cajan), green gram (Phaseolus aureus) and black gram (Phaseolus mungo Roxb) has been evaluated with respect to their limiting amino acids (methionine and tryptophan) and the protein fractions. Feeding experiments conducted on wistar albino rats showed a significant improvement in the biological value (BV) on rice-pulse mixed diets as compared to rice alone. However, significant reduction in the true digestibility (TD) of rice-pulse diets was observed when rice was mixed with black gram and red gram.