Seed Protein Quality Research Articles

Proximate and Mineral Composition, Protein Quality of Hibiscus Sabdariffa L. (Roselle) Seeds Cultivated in Two Agro Ecological Areas in Cameroon

The chemical composition and protein quality of raw, boiled, toasted and soak-toasted roselle seeds harvested in the North (area I) and West (area II) regions of Cameroon were investigated in this study. To conduct the growth and nitrogen balance study, sixty albinos wistar rats of 21 to 25 days separated into ten groups of six rats/group were used and fed for fourteen days with 10% (w/w) isoproteinous experimental diets. These groups were Protein free diet (D0), egg white-standard reference protein diet (D1) and raw (D2I, D2II), boiled (D3I, D3II), toasted (D4I, D4II) and soak-toasted (D5II, D6II) roselle seed diets. Transaminases, serum creatinine, haematocrit, lipid parameters were also assessed in the rats. Results showed that crude protein, lipid, fiber and ash content of seed samples ranged respectively from 22 to 26, 18 to 22, 18 to 23 and 4.3 to 6.4%. The contents of Ca, Mg, K, Na, P, Fe and Zn were ranged from 1054 to 1920, 1670 to 2083, 26.45 to 272.7, 14 to 22, 10.58 to 90.78, 137.3 to 169.22 and 10.13 to 70.11 mg/kg respectively. Food intake was higher (P<0.05) for groups D1, D3I and D3II than for others groups. The rats fed with reference diet followed by boiled seed diets had the highest (P<0.05) weight gained, protein efficiency ratio (PER), net protein ratio (NPR), feed efficiency (FE), efficiency of food utilization (EFU) and true digestibility (TD). Aspartate aminotransferase and alanine aminotranferase were highest (p<0.05) in the rats fed raw roselle seeds. Compared to reference diet, the total cholesterol (TC), triglycerides (TG) and LDL-C of rats fed with diet D5II decreased while the HDL-C did not show any significant changes in these rats (p˃0.05). These findings show that roselle seeds cultivated in Cameroon have important amount of macronutrients and minerals. Proteins of roselle seeds are of good quality especially from the boiled seeds and are not influenced by the agro ecological region. Consumption of roselle seeds might be beneficial for cardio protective effect and no toxicity was observed as far as transaminases are concerned except that for the raw seeds which showed significant hepatotoxicity.

Amino acid profiles and quality from lotus seed proteins

Protein composition, amino acid profile and nutritional value of the lotus seed and its Osborne fractions were investigated. The seed was rich in protein with 19.85%, and showed well balanced amino acid composition compared with FAO/WHO pattern, Its nutritive properties were similar to those observed in the reference soybean protein. Phenylalanine, tyrosine, leucine and lysine were the limiting amino acids in the seed proteins. The albumin and globulin were the main protein fraction, the amino acid profile and nutritional value were close to the seed protein. Changes in transition temperature and thermal stability were observed through different solvent extractions. Albumin possessed the predominant thermal stability (81.4 °C) followed by globulin (74.49 °C), prolamin (69 °C) and glutelin (65.6 °C). So, solvent compositions influence the profile of AAs and their nutritive value, and aqueous solvent with 0.1 mol L⁻¹ NaCl was an efficient protein solubiliser. The results indicated that the extraction processes influenced the lotus seed protein quality and thermal stability. Overall, the study revealed that the lotus seed protein was nutritionally well-balanced protein and might be of significant importance in the formulation of diets for humans.

Seed protein amino acid composition of important local grain legumes Lupinus angustifolius L., Lupinus luteus L., Pisum sativum L. and Vicia faba L.

With 3 figures and 5 tables AbstractGrain legumes are regarded as highly valuable protein source for human and animal nutrition. Legume protein quality is mainly limited by the amino acids (AAs) tryptophan and sulphur AA. Organic farming in particular requires high seed protein quality for livestock feeding, as chemically produced AAs must not be feeded. Breeding attempts to increase contents of limiting AA are required. In the present survey, the AA content of 107 cultivars of important European grain legume species (Lupinus angustifolius, Lupinus luteus, Pisum sativum and Vicia faba) was analysed. AA contents were related to the requirements of growing pigs and human nutrition. Feed quality could be enhanced by choice of high quality varieties according to ideal protein concepts. For example for sulphur, AA feed quality for pigs could be increased by up to 22% (e.g. for L. angustifolius: ideal protein = 100, sample mean = 59.7, sample maximum = 72.7). Regarding livestock nutrition, ranges of limiting AA never reached the qualities reported for soybean seeds. However, an inclusion of high quality legume lines would reduce the need for other high quality components in feed compositions.

Changes in Protein Quality and Antioxidant Properties of Buckwheat Seeds and Groats Induced by Roasting

This study focused on the evaluation of changes in protein quality and antioxidant properties of buckwheat seeds and groats induced by roasting. Changes in protein quality were indirectly measured by Maillard reaction chemical indicators such as furosine, FAST index, and browning. Characterization of antioxidant profiles of raw whole seeds, roasted whole seeds, raw groats, and roasted groats was undertaken by determining the extractable total phenolic compounds (TPC), extractable total flavonoids (TF) and individual flavonoids, lipophilic and hydrophilic peroxyl radical scavengers by ORAC(FL) assay, and scavengers of ABTS radical cations by TEAC assay. Roasting significantly decreased the total protein content of groats, whereas this parameter was not affected by the thermal treatment of whole seeds. The formation of MRPs was induced by the thermal treatment of both whole seeds and groats, thus suggesting deterioration of protein quality due to this chemical event. A significant degradation in natural antioxidants due to thermal processing was observed. Most of the peroxyl radical scavenging activity of samples was associated with hydrophilic compounds because L-ORAC(FL) values were on average 9% of the H-ORAC(FL) values. The H-ORAC(FL) values were positively correlated with extractable TPC contents (r = 0.51) and extractable TF contents (r = 0.93), whereas they showed a negative correlation with furosine (r = -0.87), FAST index (r = -0.85), and browning (r = -0.98) results.

Effect of roasting and pressure-cooking on nutritional and protein quality of seeds of mangrove legume Canavalia cathartica from southwest coast of India

Raw and processed (roasted and pressure-cooked) seeds of mangrove wild legume ( Canavalia cathartica) of southwest coast of India were evaluated for nutritional and antinutritional qualities. The seeds consist of 28–32% proteins and 1600–1630 kJ/100 g of energy. A significant difference was seen between the proximate composition of raw and pressure-cooked seeds ( P < 0.05 , t-test). Among the minerals, potassium was highest (240–828 mg/100 g) followed by phosphorus (84–120 mg/100 g) and sodium (21–41 mg/100 g). Globulins (18.2%) constituted the bulk of the seed proteins followed by albumins (7.3%) as in most of the legumes. Unlike the pressure-cooked seeds, SDS-PAGE revealed three protein bands in roasted seeds (51.4, 39 and 33.1 kDa) indicating partial or complete denaturation. The essential amino acids (EAA): cystine+methionine of processed seeds exceeded than that of rice; cystine+methionine, tyrosine+phenylalanine and lysine of the roasted seeds and cystine+methionine of pressure-cooked seeds were higher than FAO/WHO pattern. Threonine, valine and isoleucine of roasted seeds were comparable to FAO/WHO pattern, so also valine, isoleucine and lysine of pressure-cooked seeds. The carbohydrates, polyunsaturated/saturated fatty acid ratio and sulphur-amino acids were higher than soybeans. The raw seed flours were devoid of tannins and trypsin inhibitors, in addition, thermal processing decreased total phenolics and hemagglutinins. Growth and nitrogen balance studies in rats were performed to determine food efficiency ratio, protein efficiency ratio, net protein retention (NPR), protein retention efficiency (PRE), true digestibility, biological value (BV) and net protein utilization (NPU) of roasted and pressure-cooked seeds. Pressure-cooked seeds showed better biological indices than roasted seeds. Except for NPR, PRE, BV and NPU, rest of the parameters analyzed for protein quality was significantly different between roasted and pressure-cooked seed diet ( P < 0.05 , t-test). Our study clearly indicated that Canavalia cathartica seeds of mangroves possess high protein and EAA. Even though domestic roasting and pressure-cooking partially detoxified con A-like lectins or hemagglutinins, improved methods of processing are essential to maximize the quality of protein with minimum loss of seed nutrients. This is the first study on the biochemical and protein quality evaluation of mangrove bean, Canavalia cathartica and warrants its conservation and utilization as a future potential protein source for humans and or livestock.

Nitrogen Fertilizer Increases Seed Protein and Milling Quality of Rice

ABSTRACTRice grain breakage during milling is a problem in many parts of Asia. It has been suggested that nitrogen (N) fertilizer can improve the milling quality of rice. Therefore, this study investigates effects of N fertilization on grain N concentration, endosperm storage protein distribution, and milling quality of rice. Four Thai extra long grain commercial rice cultivars (KDML105, KLG1, PTT1, and CNT1) were grown at Chiang Mai University in the wet season of 2001 with 0 or 120 kg of N/ha at flowering. Anatomical sections showed that there was more storage protein accumulated in the lateral regions of polished grain of high N concentration than in grain of low N concentration. Percent (%) unbroken rice was positively correlated with relative abundance of storage protein in the lateral region of the endosperm in all cultivars. Applying N increased head rice N concentration in all cultivars, whereas % unbroken rice was increased in KLG1 and CNT1. KDML105 cultivar, on the other hand, already had high % unbroken rice and more abundant storage protein in the lateral region with the grain of low N concentration. It is hypothesized that high density of storage protein in the lateral region of the endosperm provides resilience and lessens grain breakage during milling. The additional protein may increase hardness in rice grains and thus could make the rice more resistant to breakage during milling. Furthermore, N fertilization may enhance the nutritional quality of rice grain by increasing the glutelin content, which is rich in lysine.

Nutritional study of raw and popped seed proteins of Amaranthus caudatus L and Amaranthuscruentus L

AbstractThe nutritional value of raw and popped (similar to popcorn preparation) seed proteins of two amaranth species, Amaranthus caudatus L and A cruentus L, was investigated. After popping, the true protein content in A caudatus and A cruentus decreased by 9 and 13% respectively. Among the amino acids, the loss of tyrosine due to the popping effect was the highest, followed by phenylalanine and methionine. Leucine was the first limiting amino acid in the raw samples, followed by lysine, while the reverse order was observed in the popped samples. The in vivo protein quality of raw and popped seeds was tested with male weanling rats and compared with wheat flour and casein samples. There was no difference between the in vivo digestibility of the raw and the popped seeds, although the in vitro digestibility was slightly higher for the popped samples. The protein efficiency ratio (PER) for all the amaranth seed samples was higher than that for the wheat sample, while the PER for the raw amaranth seed samples was close to that for the casein reference protein. The rat blood serum levels of total cholesterol, triglycerides and high‐density lipoprotein cholesterol for all the amaranth samples were lower than those for the reference protein, while the wheat flour sample showed the lowest values. Copyright © 2004 Society of Chemical Industry

Nutritional evaluation of some Nigerian wild seeds.

Some wild seeds, namely Parkia biglobosa, Tetracarpidum conophorum, Pentaclethra macrophylla, Irvingia gabonensis, Afzelia africana, Prosporis africana and Monodora myristica, were randomly collected from various parts of Nigeria and analyzed with regard to their proximate, mineral, antinutrient composition and zinc bioavailability. The results revealed that the seeds had high protein (6.5-24.2%), fat (19.0-58.5%), mineral (Mg, Fe, Zn, Mn, Ca, Na, K, P) and phytate (1043.6-2905.2 mg/100 g) contents, while the cyanide content was low (3.7-6.4 mg/kg). However, Co, Pb and Ni were not detected in all the samples. The calculated [Ca] [phytate]/[Zn] molar ratios (which is the best index for predicting Zn bioavailability) for all the seeds revealed that Parkia biglobosa, Irvingia gabonensis and Prosporis africana had a calculated molar ratio above 0.50 mol/kg (critical level), thus indicating reduced bioavailability of Zn to a critical level. In view of the high fat, protein, mineral and low cyanide contents, the high phytate content would not be expected to reduce bioavailability of Zn in some of the wild seeds (Afzelia africana, Pentaclethra macrophylla and Monodora myristica). These wild seeds could be good nutrient sources if integrated fully into human and animal nutrition. However, further studies will be carried out on the protein quality and toxicological potentials of these wild seeds.

The redistribution of protein sulfur in transgenic rice expressing a gene for a foreign, sulfur-rich protein.

Sulfur amino acid composition is an important determinant of seed protein quality. A chimeric gene encoding sunflower seed albumin (SSA), one of the most sulfur-rich seed storage proteins identified so far, was introduced into rice (Oryza sativa) in order to modify cysteine and methionine content of the seed. Analysis of a transgenic line expressing SSA at approximately 7% of total seed protein revealed that the mature grain showed little change in the total sulfur amino acid content compared to the parental genotype. This result indicated that the transgenic rice grain was unable to respond to the added demand for cysteine and methionine imposed by the production of SSA. Analysis of the protein composition of the transgenic grain showed changes in the relative levels of the major seed storage proteins, as well as some non-storage proteins, compared to non-transgenic controls. Changes observed at the protein level were concomitant with differences in mRNA accumulation but not always with the level of transcription. The limited sulfur reserves appeared to be re-allocated from endogenous proteins to the new sulfur sink in the transgenic grain. We hypothesize that this response is mediated by a signal transduction pathway that normally modulates seed storage protein composition in response to environmental fluctuations in sulfur availability, via both transcriptional and post-transcriptional control of gene expression.

Nutritional evaluation of dried tomato seeds

Two samples of tomato seeds, a by-product of the tomato canning industry were evaluated to determine proximate analysis, amino acid content, and digestibility, TMEn, and protein efficiency ratio. Tomato seeds were also used to replace corn and soybean meal (SBM) in a chick diet on an equal true amino acid digestibility and TMEn basis. Tomato seeds were found to contain 8.5% moisture, 25% CP, 20.0% fat, 3.1% ash, 35.1% total dietary fiber, 0.12% Ca, 0.58% P, and 3,204 kcal/kg of TMEn. The total amounts of methionine, cystine, and lysine in the tomato seeds were 0.39, 0.40, and 1.34%, respectively, and their true digestibility coefficients, determined in cecectomized roosters, were 75, 70, and 54%, respectively. The protein efficiency ratio (weight gain per unit of protein intake) value when fed to chicks at 9% CP was 2.5 compared to 3.6 for SBM (P < or = 0.05). When corn-SBM diets were formulated on an equal true amino acid digestibility and TMEn basis, up to 15% tomato seeds could replace corn and SBM without any adverse affects on chick weight gain, feed intake, or gain:feed ratio from 8 to 21 d posthatch. Tomato seeds at any level in the diet did not significantly affect skin pigmentation. Although the protein quality of tomato seeds may not be as high as SBM, tomato seeds do contain substantial amounts of digestible amino acids and TMEn. When formulating diets on a true digestible amino acid and TMEn basis, tomato seeds can be supplemented into chick rations at up to 15% without any adverse affects on growth performance.

Differential Accumulation of Soybean Seed Storage Protein Subunits in Response to Sulfur and Nitrogen Nutritional Sources

Soybean (Glycine max [L.] Merr.) seed storage proteins consist of subunits that differ in amino acid profile, the β-subunit of 7S protein being essentially devoid of the S-containing amino acids, methionine and cysteine. Our objective was to examine the interaction of N and S nutrition on the relative abundance of these storage protein subunits in soybean seed. ‘Kenwood’ soybean was grown in hydroponic culture, and during vegetative growth (V2–R4.5) N was provided as 5 mM KNO3 to plants grown under sulfur-deficient (0.004 raM Na2SO4) or sulfur-sufficient (0.4 mM Na2S04) conditions. During seed fill (R4.5–R7) N was supplied as 5 mM KNO3 or 2.5 mM urea. Each N group was given S treatments of 1) no sulfur, 2) 0.4mM Na2SO4, 3) 0.2 mM L-cystine, or 4) 0.4 mM L-methionine. Effects on seed protein quality of S deficiency during vegetative growth were essentially overcome by supplying sulfate as late as R4.5. Total protein and seed storage protein were increased with urea as N source, but urea also increased the β-subunit. Provision of reduced S as methionine essentially suppressed β-subunit production, but cystine did not, suggesting that cystine did not influence methionine level in the seed. We also report the accumulation of two as yet unreported proteins which occur at extremes of S nutrition : (1) a putative β-subunit of 7S protein occurring in the embryonic axis under S-deficiency ; and (2) a ca. 14kD protein in cotyledon tissue under provision of L-methionine. Though S and N did interact to a limited extent to influence seed protein composition, major effects were from S or N acting individually.

Modification of Storage Protein Content and Quality in Legume Seeds

Abstract Worldwide, legume seed proteins represent a major source of amino acids for human and animal nutrition. However, they are notoriously deficient in sulphur-containing amino acids. Therefore attempts to overcome this imbalance are nutritionally relevant, and the concept of legume seed protein quality has been extended to technological and health-oriented aspects. This review focuses on the state-of-the-art of the conventional and innovative methodologies for the improvement of legume seed storage protein content and quality and also the constraints encountered. Modifications of storage protein quality can be achieved by conventional breeding and processing, and by genetic engineering. Various examples concerning selection of new lines by conventional breeding for the improvement of functional properties and modification of the sulphur content of the genetically engineered seeds are reported. It is becoming increasingly apparent that these two approaches are not mutually exclusive, rather they appea...

Study of the nutritional value of black cumin seeds (Nigella sativaL)

The nutritional value of five samples of black cumin seeds from five different sources available in the local market were studied. The average values of the proximate analysis on dry matter basis were 216 g kg-1 for crude protein, 406 g fat, 45 g ash, 84 g crude fibre and 249 g of nitrogen-free extract, whereas moisture content was 38 g kg-1. The mineral and vitamin analyses showed that black cumin seeds contained iron, (105 mg kg-1) copper (18 mg), zinc (60 mg) phosphorus (527 mg), calcium (1860 mg), thiamin (15.4 mg), niacin (57 mg), pyridoxine (5.0 mg) and folic acid (160 micrograms). The protein quality of black cumin seeds was evaluated using net protein utilisation (NPU), protein efficiency ratio (PER) and net dietary protein energy percent (NDPE %) for two samples imported from Syria and Turkey, while PER was determined for the Syrian sample only. The results indicated that the NPU standardised of Turkish black cumin seeds was significantly higher than that of Syrian type (P < 0.05). The mean results (+/- SD) were 54.6 +/- 2.72 for the Syrian type and 63.1 +/- 3.74 for the Turkish type. The NDPE% mean results (+/- SD) were 5.3 +/- 0.79 and 5.6 +/- 0.26 for the Syrian and the Turkish samples, respectively. The PER adjusted value for the Syrian samples was 1.9. The results of protein quality evaluation and those of the nutrient composition suggest that black cumin is of relatively good nutritional value.

Impact of microwave heating on hemagglutinins, trypsin inhibitors and protein quality of selected legume seeds.

Selected legume seeds (dry and soaked) including faba beans, peas, chickpeas, soybeans, lentils and common beans containing 8 and 25% moisture, respectively, were subjected to microwave heating, and to a conventional cooking method to determine the heating effect on toxic compounds and protein quality. Trypsin inhibitors, hemagglutinins and available lysine were analyzed, and laboratory rats were used to determine digestibility and protein efficiency ratio (PER). Results indicated that microwaving destroyed trypsin inhibitors to a similar degree to that observed in beans cooked using the conventional method without affecting PER for raw seeds with low antinutrients content (faba beans, peas, chickpeas and lentils). Microwave-heated soaked soybeans had a higher amount of destroyed trypsin inhibitors, along with a higher PER, compared with microwave-heated dry soybeans. Microwave heating of common beans failed to destroy hemagglutinins and trypsin inhibitors, and consequently their digestibility and PER values were poor. Finally it was concluded that microwave heating constitutes an adequate method for destroying hemagglutinins and trypsin inhibitors without affecting protein quality of most legume seeds, except for common beans that despite of this process retained the antinutritional substances.

Determination of the Protein Quality of Three New Northern Adapted Cultivars of Common and Miso Type Soybeans by Amino Acid Analysis

The total protein and amino acid contents of three new northern adapted soybean cultivars, namely Apache, Baron, and a miso type Maple Belle and its older male recurrent parent Evans, were compared as potentially useful indices for assessing their protein quality from their FAO/WHO amino acid scoring pattern. The total protein contents, although similar, were statistically significantly different (P > 0.05), varying from 30.1% in Baron to 31.2% in Evans, 32.3% in Apache, and 31.5% in Maple Belle. All four soybean cultivars contained an excellent balance of essential amino acids (EAA), i.e., EAA9 = 46−46.6% compared to the FAO/WHO reference protein pattern value of 33.9% for a 2−5-year-old child. All were limited only in methionine, and to a lesser extent in isoleucine and valine, and had a protein digestibility corrected amino acid score of 91% compared to the values obtained for hen's whole egg (97%). These results indicate that an accurate calculation of protein quality of soybean seeds and other legumes can be made from their amino acid composition. Keywords: Soybeans; miso type soybean; assessment; protein quality; amino acids; composition; amino acid score

Plant Proteins: Engineering for Improved Quality

Plant protein is the primary source of all dietary protein for humans and livestock. In 1992, world protein production was 137 million metric tons, of which 65% was obtained from plants directly and 35% through animal protein production.' In comparison to meat protein, plant protein is more economic to produce and convenient to transport and store. However, when used as a source of dietary protein for human and monogastric animals, most plant proteins are nutritionally incomplete because of their deficiency in certain essential amino acids. In general, cereal proteins are low in lysine (Lys) and tryptophan (Trp), and legume and most vegetable proteins are deficient in the sulfur amino acids methionine (Met) and cysteine (CYS).~ Amino acid deficiencies can be corrected in at least three ways, namely, supplementation with synthetic amino acids, supplementation with small amounts of protein which are a rich source of the deficient amino acid(s), or complementation with other protein(s) so that the combined protein sources will balance each other's deficiencies or excesses. The American animal feed industry annually spends 150 and 70 million dollars on synthetic Met and Lys, respectively, to supplement the protein base feeds. Conventional plant breeding methods have made some progress in identifying mutations with improved seed protein quality, such as high-Lys corn and barley.3 However, the undesirable traits associated with these mutations, such as lower yields and greater susceptibility to pests and diseases, have prevented their agronomic uti l i~ation.~ Because of a lack of genetic variability in Met content, efforts to breed legumes with increased levels of Met have not had significant success. Recent advances in biotechnology offer alternative approaches to improving the nutritional quality of plant proteins. These include sequence modifications, synthetic genes, overexpression of homologous genes, and transfer and expression of heterologous genes. Progress in this area of research and development was reviewed r e ~ e n t l y . ~ , ~

Protein Quality and Antinutritional Factors of Wild Legume Seeds from the Sonoran Desert

Seeds from seven species of legume trees of the Sonoran Desert were studied to determine their potential value as a nonconventional food and/or as a feed source. Seed proximal composition and protein quality were evaluated by conventional methodology. Defatted flours from Acacia farnesiana, Cercidium microphyllium, Cercidium sonorae, Mimosa grahamii, Olneya tesota, Parkinsonia aculeata, and Prosopis juliflora have protein contents that ranged from 20 to 30%. These proteins were deficient in sulfur amino acids but high in lysine and phenylalanine content. Except for M. grahamii seeds, trypsin inhibitors were relatively high in all species and varied from 50 to 70 TIU/g. Other antinutritional factors as lectins, alkaloids, saponins, and phenols were detected in all but Mimosa seeds. Protein in vitro digestibility was found to be 77−84%, and these values increased (5−10%) after a thermic treatment. The calculated C-PER values were found to be 1.8−2.1%. From the seeds of the seven species evaluated, M. graham...

Mineral Nitrogen in Plant Physiology and Plant Nutrition

Abstract Nitrogen (N) nutrition enhances metabolic processes that influences the physicochemical environment at the soil-root interface, modifies rhizosphere conditions, interferes with the uptake of cations and anions, and enhances or represses the activity of several enzyme systems. Also, it affects growth patterns, protein content, and protein quality of seeds. Ammonium (NH4)-N nutrition increases anion uptake, free amino-N/protein ratios, and acidity of root free space; it reduces carbohydrate levels in plant tissues. NO3-N nutrition results in higher cation uptake, higher carbohydrate content in tissues, and alkalinization of root free space. N-Assimilation interferes with the allocation of dry matter and energy, which causes different growth rates of plant parts. In this article we review the effects of mineral-N nutrition on uptake of cations and anions, activity of enzymes, growth patterns of roots and shoots, and water use efficiency, protein content, and protein quality of seeds.

Protein quality of legume seeds for non-ruminant animals: a literature review

Peas and field beans have been increasingly grown in Europe during the last 15 years, to improve self-sufficiency in protein-rich feedstuffs. The protein profile of these crops is characterized by a high lysine content (7.3% crude protein in peas) and a relative deficiency in sulphur amino acids and tryptophan. Protein digestibility is slightly lower than in soyabean meal, especially for pigs (0.74 in peas vs. 0.80 in soyabean meal) and for young animals, and appears variable both between and within species. This lower digestibility can partly be explained by the presence in some species or cultivars of antinutritional factors (ANF; e.g. protease inhibitors, lectins or tannins) and/or fibrous material, leading to low accessibility of legume seed protein to digestive enzymes. More work is needed to separate the effects of these factors and their practical importance. Because of the high variability of ANF activity, it also appears necessary to develop reliable and quick assays which allow a check and selection of batches by plant breeders or feed manufacturers. Owing to the high variability within each species of these characteristics it seems possible to improve the nutritional value of legume seeds by selective breeding. In the short term, technological treatments can also lead to improved utilization, especially in poultry, but attention has to be paid to the cost of these treatments.

Nutritional Quality of Hard‐to‐cook and Processed Cowpea

ABSTRACTHard‐to‐cook (HTC) defect was induced in cowpea seeds by storing at 37°C and 85% relative humidity (RH) for 6 wk. HTC and control (stored at 7°C, 60% RH) seeds were boiled for 45 and 90 min or ground to flour. Flour was cooked as paste or extruded (20% H2O, 150°C). Overall dietary quality was estimated as Feed Efficiency and Relative Response Ratio. Protein quality was determined as Nitrogen Efficiency and Relative Nutritive Value. Overall and protein nutritional quality were generally higher for control than for HTC cowpea diets. Processing affected control and HTC seeds differently. Boiling either control or HTC whole seeds improved both overall and protein quality compared to raw seeds, while extrusion substantially increased the quality of control seeds but reduced the quality of HTC seeds. Cooking as paste improved protein and overall quality of control seeds but not protein quality of HTC seeds.