Nutritional utilization by rats of chickpea (Cicer arietinum) meal and its isolated globulin proteins is poorer than that of defatted soybean or lactalbumin

The Use of Post-Natal Skeleton Development as Sensitive Preclinical Model to Test the Quality of Alternative Protein Sources in the Diet

Dietary protein is necessary throughout all life stages. Adequate intake of protein during juvenile years is essential to enable appropriate synthesis of bone matrix and achieve the full peak bone mass (PBM). Due to socio-demographic changes, accompanied by environmental damage and ethical problems, a transition to the consumption of different and alternative protein sources in the human diet must occur. This transition requires the precise evaluation of protein quality. Here, we utilize a preclinical model of young rats during their post-natal developmental period to define the nutritive quality of a number of alternative protein sources (soy, spirulina, chickpea, and fly larvae) by their health impact on growth performance and skeletal development. We indicate that when restricted (10% of calories) not one of the tested alternative protein sources have succeeded in causing optimal growth, as compared to the referenced source, casein; yet fly larvae protein followed by chickpea flour were found to be superior to the rest. Growth-plate histology and µ-CT analyses demonstrated a number of changes in growth patterns and bone morphometric parameters. Bone mechanical testing, by three-point bending analyses, was sensitive in demonstrating the effect of the reduction in the amount of the dietary protein. Moreover, the rats’ weight and length, as well as their eating patterns, were found to reflect the proteins’ quality better than their amino acid composition. Hence, our study emphasizes the importance of evaluating protein as a whole food source, and suggests a new approach for this purpose.

Proteins in Relation to Vigor and Viability of White Lupin (Lupinus albus L.) Seed Stored for 26 Years

The aim of the study was to evaluate the vigor and viability as well as to determine and compare the contents of selected protein fractions of white lupin (Lupinus albus L.) seeds stored for 26 years at temperatures of -14°C and +20°C. The seeds stored at -14°C germinated in 86.3%, while the seeds stored at +20°C did not germinate at all. The viability evaluation was confirmed by the measuring electroconductivity of seed exudates. In seeds stored at -14°C the contents of γ, δ, and β conglutin were 14, 4 and 69 mg g^-1 fresh mass, respectively, while in seed stored at +20°C they were 15.5, 3, 65 mg g^-1 fresh mass, respectively. One-dimensional electrophoresis of γ and δ conglutin fractions indicated the presence of several intense polypeptide bands with molecular weights from 23.0 to 10.3 kDa. Polypeptide bands with a molecular weight of 22.4 and 19.8 kDa exhibited almost two times higher expression in the seeds stored at -14°C compared to the seeds stored at +20°C. Electrophoresis revealed 310 protein spots on the maps generated for seeds stored at -14°C, and 228 spots for seeds stored at +20°C. In seeds stored at +20°C most polypeptide subunits had a pI ranging from 4.5 to 7 and a molecular weight of 10-97 kDa. The greatest differences in the contents of polypeptides between the analyzed variants was observed within the range of 20-45 kDa (-14°C: 175, +20°C: 115 protein spots) and within the range of 65-97 kDa (-14°C: 103, +20°C: 75 protein spots). In seeds stored at +20°C, a clear decline in basic (8-10 pI) polypeptides was observed. The study demonstrated that the polypeptides identified as γ and δ conglutins are probably closely related to vigor and viability of seeds.

Characterization of pea (Pisum sativum) seed protein fractions

BACKGROUND

Legume seed proteins have to be chemically characterized in order to properly link their nutritional effects with their chemical structure.

RESULTS

Vicilin and albumin fractions devoid of cross-contamination, as assessed by mass peptide fingerprinting analysis, were obtained from defatted pea (Pisum sativum cv. Bilbo) meal. The extracted protein fractions contained 56.7-67.7 g non-starch polysaccharides kg⁻¹. The vicilin fraction was higher than legumins in arginine, isoleucine, leucine, phenylalanine and lysine. The most abundant amino acids in the albumin fraction were aspartic acid, glutamic acid, lysine and arginine, and the amounts of methionine were more than double than those in legumins and vicilins. The pea albumin fraction showed a clear enrichment of protease inhibitory activity when compared with the seed meal. In vitro digestibility values for pea proteins were 0.63 ±  0.04, 0.88 ±  0.04 and 0.41 ±  0.23 for legumins, vicilins and albumins respectively.

CONCLUSION

Vicilin and albumin fractions devoid of cross-contamination with other proteins were obtained from pea seed meal. The vicilin fraction also contained low amounts of soluble non-starch polysaccharides and was enriched in isoleucine, leucine, phenylalanine and lysine. In vitro digestibility values for pea proteins were similar or even numerically higher than those for control proteins.

The cereal type in feed influences gut wall morphology and intestinal immune cell infiltration in broiler chickens

In broiler chickens, a diet where the major cereal types are wheat, rye and/or barley has a lower digestibility compared with a diet in which maize is the major cereal type. In the present study, the effects of two different dietary cereal types, maizev.wheat/rye, on host factors (inflammation and gut integrity) and gut microbiota composition were studied. In addition, the effects of low-dose Zn-bacitracin supplementation were examined. Broilers given a wheat/rye-based diet showed more villus fusion, a thinner tunica muscularis, more T-lymphocyte infiltration, higher amount of immune cell aggregates in the mucosa, more and larger goblet cells and more apoptosis of epithelial cells in the mucosa than those given a maize-based diet. Adding Zn-bacitracin generally reversed these alterations. The microbiota composition was analysed by the use of terminal-restriction fragment length polymorphism, showing changes in the microbiota composition depending on the cereal type used in the diets. The effect of the change of cereal type on the gut microbiota composition was larger than that of Zn-bacitracin supplementation. In conclusion, a wheat/rye-based diet evoked mucosal damage, an alteration in the composition of the microbiota and an inflammatory bowel type of condition.

Nutritional responses of rats to diets based on chickpea ( Cicer arietinum L.) seed meal or its protein fractions

The aim of this study was to isolate the protein fractions from chickpea, var. IAC-Marrocos, as well as to evaluate its in vivo nutritional protein quality. Among the proteins, albumins showed better nutritional value in the in vivo assays and amino acid contents, despite their higher trypsin inhibitor contents. Trypsin inhibitors were found to be heat labile in all samples, but the digestibility results for unheated and heated flour and albumins suggest that their contents are not very decisive. The PER values for casein (not supplemented) were very similar to those of heated flour and unheated or heated albumin and total globulins. The albumin and glutelin fractions showed the best results for PDCAAS, however, lower than those of casein. Despite the high digestibility of the globulin the very low essential amino acid content lowered its PDCAAS, and it had the lowest values.

Using blood urea nitrogen to predict nitrogen excretion and efficiency of nitrogen utilization in cattle, sheep, goats, horses, pigs, and rats

The objectives of this study were to evaluate the potential for using blood urea N concentration to predict urinary N excretion rate, and to develop a mathematical model to estimate important variables of N utilization for several different species of farm animals and for rats. Treatment means (n = 251) from 41 research publications were used to develop mathematical relationships. There was a strong linear relationship between blood urea N concentration (mg/100 mL) and rate of N excretion (g x d(-1) x kg BW(-1)) for all animal species investigated. The N clearance rate of the kidney (L of blood cleared of urea x d(-1) x kg BW(-1)) was greater for pigs and rats than for herbivores (cattle, sheep, goats, horses). A model was developed to estimate parameters of N utilization. Driving variables for the model included blood urea N concentration (mg/100 mL), BW (kg), milk production rate (kg/d), and ADG (kg/d), and response variables included urinary N excretion rate (g/d), fecal N excretion rate (g/d), rate of N intake (g/d), and N utilization efficiency (N in milk and gain per unit of N intake). Prediction errors varied widely depending on the variable and species of animal, with most of the variation attributed to study differences. Blood urea N concentration (mg/100 mL) can be used to predict relative differences in urinary N excretion rate (g/d) for animals of a similar type and stage of production within a study, but is less reliable across animal types or studies. Blood urea N concentration (mg/100 mL) can be further integrated with estimates of N digestibility (g/g) and N retention (g/d) to predict fecal N (g/d), N intake (g/d), and N utilization efficiency (grams of N in milk and meat per gram of N intake). Target values of blood urea N concentration (mg/100 mL) can be backcalculated from required dietary N (g/d) and expected protein digestibility. Blood urea N can be used in various animal species to quantify N utilization and excretion rates.

Lupin (Lupinus albus) protein isolate (L-ISO) has adequate nutritional value and reduces large intestinal weight in rats after restricted and ad libitum feeding

BACKGROUND

A protein isolate from white lupin (Lupinus albus; L-ISO) has potential as a novel human food ingredient, but its nutritional effects are unknown.

METHODS

We evaluated protein quality and effects on body composition in rats of isoenergic diets of L-ISO, lactalbumin, or casein with both restricted (10-day) and ad libitum (28-day)intake. The diets were equivalent in protein per se, but supplementation was used to balance essential amino acid levels.

RESULTS

In both studies, the rats consumed similar amounts of each diet, and no effect of diet on the gain:feed ratio was observed--though gain:N ratio and net protein utilization were slightly lower for the L-ISO diet. Lower large intestinal weights after the L-ISO than after the lactalbumin diet were observed in both studies. The L-ISO diet resulted in lowered body fat percentage in the 10-day study but in an elevated level in the 28-day study. Liver composition (DNA, RNA, glycogen, and fat) and plasma levels of some amino acids (His, Thr, Ala, Pro, Tyr, Val and Met) were affected by diet, but no effects on plasma lipid, glucose, or uric acid were observed.

CONCLUSION

The L-ISO diet did not affect feed intake and has adequate nutritional quality in rats whilst modifying large intestinal weight in a potentially beneficial manner--suggesting potential for this protein in human nutrition.

Nutritional Evaluation of Raw and Extruded Kidney Bean (Phaseolus vulgaris L. var. Pinto) in Chicken Diets

An experiment was conducted to study the effect of inclusion of different concentrations (0, 100, 200, and 300 g/kg) of raw kidney bean and extruded kidney bean in broiler chick (0 to 21 d of age) diets on performance, digestive organ sizes, protein and amino acid digestibilities, intestinal viscosity, cecal pH, and blood parameters. Data were analyzed as a 3 x 2 factorial arrangement with 3 levels of kidney bean with and without extrusion. Positive control without kidney bean was used. Increasing the kidney bean content in the diet reduced weight gain and consumption, and increased the feed-to-gain ratio. Relative pancreas, liver, and jejunum weights, and intestinal viscosity were increased in response to increasing kidney bean concentration in the diet. The inclusion of different concentrations of kidney bean did not affect the apparent ileal digestibility of essential and nonessential amino acids, except for Met, Phe, and Cys, which were increased. Increasing kidney bean in the diet did not affect blood parameters, except for total protein, which was increased, and for androstenedione and testosterone, which were reduced. Extrusion significantly improved weight gain, feed consumption, and feed conversion. Relative pancreas, liver, and jejunum weights were reduced and spleen weight, cecal and intestinal viscosity were increased by extrusion. Apparent ileal digestibility of crude protein and all essential and nonessential amino acids were improved by extrusion. Like-wise, extrusion increased significantly the concentrations of cholesterol, triglycerides, glucose, and testosterone. We concluded that the inclusion of kidney bean in chicken diets cause a negative effect on performance and CP and amino acid digestibilities, and modified digestive organ sizes, intestinal viscosity, cecal pH, and some blood parameters. These effects were counteracted by the extrusion of kidney bean. However, the inclusion of extruded kidney bean in a chick diet resulted in poorer performance compared with that obtained with a corn-soybean diet.

Carbohydrates digestibility and faecal nitrogen excretion in rats fed raw or germinated faba bean (Vicia faba)- and chickpea (Cicer arietinum)-based diets

Raw or germinated faba bean (Vicia faba minor var. Alameda) and chickpea (Cicer arietinum kabuli var. Athenas) seed meals were incorporated in essential amino acid-supplemented and energy-equalized diets for growing (65 (SD 1) g) male Wistar rats as the only sources of dietary protein. A lactalbumin-based diet was used as the control. Faecal dry weight and N excretion of animals fed legume-containing diets were greater (P<0.01) and DM digestibility lower (P<0.01) than controls. Apparent faecal digestibilities of amino acids were found to be not different or lower (P<0.01) than controls in rats fed diets containing legume seeds, either germinated or not. Total diaminopimelic acid (DAPA) and purine bases excretion were significantly (P<0.01) higher than controls in rats fed both legume seed meals. Faecal bacterial N calculated according to DAPA or purine bases values was similar and significantly higher (P<0.01) than controls in rats fed legume seed meals. Bacterial N accounted for 50 to 80 % of total faecal N in rats fed legume diets. Apparent faecal N digestibility values (53-65 %) of rats fed legume-based diets were lower (P<0.01) than controls, but became substantially higher (85-92 %) when calculated taking into account bacterial N values. Faecal NSP digestibility values for legume diets were 40-57 g/100 g ingested. Germination decreased starch faecal excretion (P<0.05) and increased (P<0.05) faecal starch and NSP digestibilities of faba bean seeds.

Transport of amino acids from in vitro digested legume proteins or casein in Caco-2 cell cultures

Purified legume storage proteins (chickpea 11S and 7S globulins, faba bean globulins, and lupin globulins) and casein (casein) were subjected to an in vitro enzyme (pepsin + pancreatin) digestion process. Protein digests were then used in a bicameral Caco-2 cell culture system to determine amino acid transport across the cell monolayer. With digests from legume proteins, absolute amounts of aspartate, glycine, and arginine transported were higher than those found in digested casein, whereas amounts of glutamate, proline, tyrosine, valine, and lysine were lower. However, proportions of amino acids in the basolateral chamber as compared with amounts added in the apical chamber were lower than casein controls for all amino acids except cystine. Results confirm previous in vivo observations that amino acids from legume proteins are probably absorbed at rates different from those in other proteins of animal origin such as casein.

Nutritional utilization by the rat of diets based on lentil (Lens culinaris) seed meal or its fractions

The nutritional effects in the rat of raw lentil meal or its fractions have been evaluated in three feeding trials. Growth, gain/feed ratio, apparent N digestibility, and N retention were significantly (p < 0.05) reduced by the inclusion of whole lentil meal, dehulled lentil meal, or ethanol-extracted lentil meal as the sole source of protein in the diet. Pure lentil lectin and lectin-depleted albumin proteins had no significant negative effect on nutritional performance. In contrast, growth, gain/feed ratio, protein conversion efficiency, N digestibility, and N retention were significantly (p < 0.05) reduced by diets containing lentil globulins or lentil hulls. The poor nutritional quality of raw lentil meal for rats is therefore likely to be primarily due to the combined effects of these two components.

The influence of the albumin fraction on the bioavailability and postprandial utilization of pea protein given selectively to humans

Pulse seed proteins such as those found in peas (Pisum sativum) contain fractions of very dissimilar composition and properties, which may therefore be differently utilized by the human body. To analyze the nutritional value of the soluble protein fractions of pea seed, human volunteers ingested a mixed meal of 30 g of raw purified pea protein either as [15N]-globulins (G, n = 9) or as a mix of [15N]-globulins and [15N]-albumins (GA, n = 7) in their natural proportions (22:8). Dietary and endogenous nitrogen fluxes at the terminal ileum were assessed using a tube perfusion technique with an isotopic dilution method. Systemic dietary amino acid availability and the retention of dietary amino acids were determined using 15N enrichment in plasma amino acids and deamination products in blood and urine for 8 h postprandially. The results showed that the pea albumin fraction had the following effects: 1) significantly lowered the real ileal digestibility of pea protein (94 +/- 2.5% for G vs. 89.9 +/- 4% for GA), probably because of a direct effect of trypsin inhibitors; 2) did not promote acute intestinal losses of endogenous nitrogen; and 3) did not significantly improve the postprandial biological value of pea protein (76.5 +/- 3.9% for G vs. 78.7 +/- 3.6% for GA), despite the fact that it corrected the globulin deficiency in sulfur amino acids. We conclude that both G and GA are of good nutritional value for humans and show that cysteine-rich albumins have a far more modest effect on the efficiency of postprandial dietary protein utilization than would be expected from the amino acid scores.

Hormone-related, muscle-specific changes in protein metabolism and fiber type profile after faba bean intake

Male growing Wistar rats were fed, over 15 days, isoenergetic (16.72 +/- 0.49 MJ) and isoproteic (11%) diets containing either lactalbumin or raw Vicia faba L. (Vf) as the sole source of protein. Compared with pair-fed controls (PF), soleus muscles of Vf-fed rats showed increased (P < 0.05) synthesis and breakdown rates. In addition, the soleus of Vf-fed rats displayed a decrease (P < 0.05) in type I and an increase (P < 0.01) in type IIc fibers compared with that of PF animals. On the contrary, extensor digitorum longus muscles of both Vf-fed and PF rats showed an increase (P < 0.01) in type I and a reduction (P < 0.05) in type IIb fibers together with a decrease (P < 0.05) in the cross-sectional area of the latter fibers. Vf-fed rats exhibited a significant decrease in serum insulin (P < 0.05) and thyrotropin (P < 0.01) levels, together with an increase in plasma glucagon (P < 0.05) and 3,5,3'-triiodothyronine (P < 0.01) concentrations, compared with the PF group. Both Vf-fed and PF rats experienced an increase in corticosterone concentrations (P < 0.01 vs. control; P < 0.05 vs. PF). The muscle-specific changes in both protein metabolism and fiber type composition may partly depend on the hormonal changes that were observed after Vf intake.