Physical,nutritional and antioxidant properties of Zimbabwean bambara groundnut and effects of processing methods on their chemical properties

This study examined the physical, nutritional and antioxidant properties of popular Zimbabwean bambara groundnut landraces and the effects of different processing methods on their chemical properties. The physical, nutritional and antioxidant properties of grains of the bambara landraces differed significantly with grain type, and the processing methods investigated had varying effects on the chemical properties of the grains. Bambara had significantly lower protein content than the reference common bean. Protein and carbohydrate content of the grains increased upon dehulling, while tannin (approx. 36%), total phenolic content (approx. 83%) and antioxidant activities (approx. 18%) decreased. Roasting alone seemed to have little or no effect on the nutrient content of the grains, while sifting significantly reduced the phenolic content and antioxidant activity of all the dehulled and roasted samples. The results indicate that roasting bambara grains would be a suitable method as it is relatively more conservative of nutrients and antioxidants than the other methods investigated.     

Vegetable milk processing and rehydration characteristics of bambara groundnut [Voandzeia subterranea (L.) thouars]

Eight cultivars of bambara groundnut [Voandzeia subterranea (L.) Thouars] were studied to determine their rehydration characteristics. Seeds from all cultivars approximately doubled their weight after 36 h and were then easily dehulled. Losses of nutrients to the soak water during this period were small. Mature seeds from one cultivar were evaluated for suitability as a base for a vegetable milk. Homogenisation of whole seed flour in water together with coconut or soya bean oils yielded an emulsion containing 20 g protein (Nx 5.71) and 30 ml oil litre-¹. Good emulsion stability was maintained after pasteurisation. Curds, similar to those traditionally prepared from soya beans, were easily prepared from bambara groundnut milk. The bland, creamy-white product which was high in protein had a trypsin-inhibitor content very much lower than that of the untreated vegetable milk.     

Oligosaccharide Content of 20 Varieties of Cowpeas in Nigeria

Mature dry seeds of 20 varieties of cowpeas (Vigna unguiculata) grown in Nigeria were analyzed for their sucrose, raffinose and stachyose content. The dry seeds were ground into powder, extracted with 80% ethanolandthe extract analyzed by paper chromatography using a mixture of n-butanol, ethanol, water and ammonia solution 8:1:2:1 v/v). The results show a progressive decrease in raffinose and stachyose content with dehulling and cooking and an increase in sucrose level after cooking. The average content of the sugars in whole beans on dry weight basis was sucrose 0.8%, raffinose 2.6% and stachyose 3.3%. The average content for dehulled raw beans were sucrose 0.7%, raffinose 1.8% and stachyose 2.4% while in cooked beans it was 1.6%, 1.3%, and 1.8%, respectively.     

Studies on the nutritive characteristics and fracture resistance to compressive loading of selected bambara groundnut lines

Extensive laboratory experiments were conducted to determine the nutritive characteristics and fracture resistance to compressive loading of some bambara groundnut lines. Data obtained showed percentage carbohydrate, protein and oil contents of 52.60, 17.52 and 6.66 respectively for dehulled bambara groundnut seeds as against lower percentage values of 48.60, 16.99 and 6.20 obtained from the analysis of whole seeds of BgB-Br. Investigations on the mechanical properties revealed that the force needed to rupture the seeds was influenced by moisture content and loading position of the seeds. The force was found to decrease from 262 to 100 N with increase in moisture content, while the deformation increased from 1.9 to 4.5 mm with increase in moisture content. Maximum toughness occurred at different moistures which represent the moisture levels for absorbing compressive energy which are important for resisting mechanical damage during handling of the bambara groundnut lines. © 1999 Society of Chemical Industry     

Oxidation of polyphenols in unfermented and partly fermented cocoa beans by cocoa polyphenol oxidase and tyrosinase

Unfermented and partly fermented dried cocoa beans have an excessively astringent and bitter flavour owing to their high polyphenol content. Studies on the remaining polyphenol oxidase activity and the oxidation of polyphenols in these beans have been conducted in relation to two factors, ie incubation time (0, 1, 2, 4, 8 and 16 h) and pH of incubation (3.5, 4.5, 5.5 and 6.5). Owing to unsuccessful polyphenol oxidation during incubation of partly fermented beans, incubation–enrichment treatments were carried out by combining incubation time (0, 8, 16, 24 and 32 h) and addition of crude cocoa polyphenol oxidase and purified tyrosinase from mushroom at 88 and 8800 units g^?1 and pH 5.5. Results showed that the remaining polyphenol oxidase activities of unfermented and partly fermented dried beans were 1 and 0.08% with specific activities of 9 and 1% respectively. The polyphenols of unfermented beans were effectively oxidised by incubation at 45 °C and pH 3.5–6.5 without enzyme enrichment; while those of partly fermented beans required enzyme enrichment. Both crude cocoa polyphenol oxidase and tyrosinase could be used for enzyme enrichment, but tyrosinase seemed to be more effective. © 2002 Society of Chemical Industry     

Efficiency of some technological processes on reducing the residues of malathion and pirimiphos methyl in mature broad bean seeds

Residue study was performed on several insecticides which could contaminate local Egyptian beans. The effect of storage periods and various processing steps on lowering the residues of malathion and pirimiphos methyl in treated seeds and their processed products were investigated. The data indicated that malathion and pirimiphos methyl persisted for more than 90 days on and in stored mature dry broad beans after postharvest treatment. However, stored broad beans could be safely used for human consumption after 90 days when the insecticide residues reached safe levels. Washing removed 69 and 75% of malathion and pirimiphos methyl residues of treated broad beans, respectively. Malathion residue was not detected in various processed products. More than 89 and 99% of malathion residues were absent in dehulled and heated dehulled broad beans. In addition, pirimiphos methyl residues were reduced to 92, 97, 87, 99, 99, and 95% from the initial levels in treated beans following dehulling, cooking of dehulled beans, germination, cooking of germinated beans and cooking of the beans by the common method and under pressure, respectively.     

Status of pulse milling processes and technologies: A review

Pulses are essential component of the human diet in the underdeveloped and the developing countries. Pulse milling mainly focuses on complete removal of the hull with minimum generation of powder, broken, and in certain cases dehulled split formation. Physical and mechanical properties of different pulses are described and their role in dehulling is discussed in this review. The review discusses nature of gums that binds hull and cotyledons together and their effect on milling characteristics. Pitting operation is performed for all pulses prior to the pretreatment for better dehulling. Various pretreatment processes (soaking, edible oils, chemicals, enzymes, hydrothermal) developed to loosen the bond are examined for their dehulling efficacy from commercial application viewpoint. Dependence of dehulling characteristics of different pulses on size, shape, variety, grain hardness, and moisture content are discussed. Most of the machines developed for pulses dehulling in India are abrasion based emery-cylinder concave system. The studies done for optimization of different pretreatment process conditions are also reviewed. The losses taking place in the form of broken and powder during pulse milling are described. Methods for performance evaluation of the pulse dehulling system are reviewed and expressions are suggested for proper evaluation. This review gives complete overview of the processes and technological status of pulse milling in present context.     

Antioxidant activity and DNA protection against oxidative damage of bambara groundnut seeds (Vigna subterranea (L.) Verdc.) as affected by processing methods

This research investigated the effects of processing by dry heating, boiling, and steaming on the antioxidant activity and DNA protection against oxidative damage of bambara groundnut seeds (Vigna subterranea (L.) Verdc.). Comparing raw and processed samples of bambara groundnut seeds, dry heating caused a significant (P < 0.05) reduction of ferric-reducing antioxidant power (FRAP), metal chelating activity, DPPH^? and ABTS^?+ radical scavenging activity. The boiling process did not cause a significant difference in FRAP and metal chelating activity and caused smaller losses in DPPH^? and ABTS^?+ radical scavenging activity than the dry heating and steaming processes. The steaming process caused a significant (P < 0.05) reduction of FRAP, DPPH^? and ABTS^?+ radical scavenging activity. For DNA protection against oxidative damage, boiled and steamed bambara groundnut seed samples were more effective with a lower minimum concentration (50 µg/mL) than raw and dry heated samples. These results indicated that the boiling process caused smaller losses antioxidant activity than dry heating and steaming. Therefore, boiling was recommended as processing method for bambara groundnut seeds to preserve antioxidant components and antioxidant activity.     

Optimisation of hydrothermal treatment for dehulling pigeon pea

This study was carried out to investigate the effect of hydrothermal treatment and drying time at a constant drying temperature of 50 °C on the dehulling behavior of pigeon pea seed. Response surface methodology (RSM) based on a two-factor, five-level, central composite design was employed to study the effect of the independent variables and optimize processing conditions. A second-order polynomial model described dehulling quality in terms of: (1) dehulled seeds, (2) undehulled seeds, (3) broken seeds, (4) powder loss and (5) dehulling efficiency. The process parameters showed significant effects on dehulled seeds and dehulling efficiency. The optimized processing conditions for maximum dehulled seeds, dehulling efficiency and minimum powder loss were a hydrothermal treatment time of 10.2 min and a drying time of 2.9 h.     

Studies on bambara groundnut flour performance in Okpa preparation

Bambara groundnut flours of different particle sizes were prepared after bean seeds had been cold‐soaked and/or germinated, dried, milled and sieved. The flours were used to prepare okpa (local dish prepared by steaming mashed bambara groundnut) and their sensory properties determined. Viscosity of the flour pastes, before steaming, were also determined. Results showed that bambara groundnut flours from both germinated and cold‐soaked beans could be used in preparing good quality okpa and, therefore, remove all the problems involved in preparing the raw beans for okpa‐making as is done traditionally. Particle size appeared to play a major role in obtaining good okpa; therefore flours intended for okpa preparation should be such that 66, 86 and 96%, respectively, of cold‐soaked bean flour or 58, 78 and 91%, respectively, of germinated bean flour, after 1, 3 and 5 milling passes, should be in the particle range 1.5–4.5 × 10^?4 m. Slightly higher amounts of the coarse (6.0 × 10^?4 m) particles are needed in the germinated bean flours to compensate for the breakdown of starch and proteins, the gelling agents in bambara groundnut. Copyright © 2004 Society of Chemical Industry     

Effects of Dehulling on Phytic Acid, Polyphenols, and Enzyme Inhibitors of Dry Beans (Phaseolus vulgaris L.)

Effects of dehulling on phytic acid; trypsin, chymotrypsin, and α-amylase inhibitory activities; and tannins of ten cultivars of dry beans (Phaseolus vulgaris L.) were investigated. Phytic acid content of whole beans ranged from 1.16-2.93%. Dehulling significantly increased the phytic acid content of beans (range 1.63-3.67%). Dehulling also increased trypsin, chymotrypsin, and α-amylase inhibitory activities of the beans. Tannin contents of whole and dehulled beans ranged from 33.7-282.8 and 10.0-28.7 me. catechin equivalent/100g beans, respectively. Removal of seed coats lowered the tannin content of beans by 68–95%. Tannins were not detected in white seeded cultivars of Sanilac, Great Northern, and Small White. Dehulling significantly improved the in vitro digestibility of bean proteins.     

Effect of legume seed extracts on the inhibition of proteolytic activity and muscle degradation of fresh water prawn (Macrobrachiumrosenbergii)

Trypsin inhibitors in the extracts from soybean (Glycine max), adzuki bean (Vigna angularis), bambara groundnut (Vigna subterranea) and red kidney bean (Phaseoulus vulgaris) varied in amount and molecular weight. The soybean extract had the highest level of trypsin inhibitor with molecular weight (MW) of 21 kDa, followed by bambara groundnut extract possessing trypsin inhibitor with MW of 15 kDa. Both extracts showed a more effective inhibition towards crude protease extract (CE) from the hepatopancreas of fresh water prawn (Macrobrachium rosenbergii) than the extracts from adzuki and red kidney beans. Activity staining also reconfirmed the higher inhibitory activity on CE from hepatopancreas by the extracts from both soybean and bambara groundnut. The extracts from all seeds were able to inhibit the degradation of fresh water prawn meat containing CE in a concentration dependent manner. Based on inhibitor study, the extracts from soybean and bambara groundnut can be a potential aid to suppress the muscle softening of fresh water prawn, mediated by trypsin-like proteases released from hepatopancreas, during extended iced storage.     

Effect of fermentation and dehulling on starch,total polyphenols,phytic acid content and in vitro protein digestibility of pearl millet

Two pearl millet cultivars: Standard and Ugandi, obtained from El Obeid Research Station, were used in this study. Investigation showed that the Ugandi variety had significantly (P⩽0.05) higher polyphenols and phytic acid contents than the standard and significantly lower in vitro protein digestibility (IVPD), (72.7 and 70.4% for the Standard and Ugandi, respectively), indicating lower nutritional quality. The two cultivars were fermented for 14 h at room temperature (30±2° C) and starch, polyphenols, phytic acid and IVPD were determined at 2-h intervals. Dehulling was found to cause a significant reduction in protein, polyphenols and phytic acid contents for the two cultivars. Fermentation and dehulling caused a significant increase in the IVPD for the two cultivars: 82 and 84% for the fermented ones and 79.1 and 78.6% for the dehulled samples.     

Splitting and dehulling lentil (Lens culinaris): Effects of seed size and different pretreatments

A conservative estimate of 800 000 T of red-cotyledon microsperma lentil (Lens culinaris Medikus) is consumed annually after postharvest processing into split dehulled seed. This process consists of cleaning the seed of foreign matter, brief immersion in water, spin-drying, standing to temper, separation into seed size fractions, dehulling/splitting and final separation. The effects of seed size (4 and 4.5 mm fractions), immersion times (1, 5, 10 and 30 min), temperature (19° and 36°) and duration (0, 30, 60 and 120 min) of air drying, and tempering time (0 and 24 h), on the efficiency of dehulling and splitting lentil were examined. Dehulling efficiency (%) was estimated as the sum of split dehulled seed, whole dehulled seed, and whole hulled seed (whole seeds are separated for recycling to the dehuller). Dehulling efficiency was best with the small seed fraction (4 mm), an immersion time of 1 min, no air drying, and a tempering time of 24 h. The drying air temperature did not have a significant effect on dehulling efficiency. Dehulling efficiency was highest with a low seed moisture content.     

Effects of dehulling,soaking and germination on chemical composition,mineral elements and protein patterns of faba beans (Vicia faba L.)

The effects of dehulling, soaking and germination on the changes in general chemical composition, nine mineral elements and the protein patterns of whole faba beans were studied. Such pretreatments had a significant effect on the changes in the chemical composition of whole beans. Dehulling of beans significantly increased the contents of copper, zinc and potassium, while it significantly decreased the amounts of iron, manganese, phosphorus, calcium, magnesium and sodium compared with whole beans. Whole beans soaked for 12 h, followed by dehulling, had higher amounts of iron, copper, zinc, calcium and sodium, and quite a lower level of potassium, than unsoaked dehulled beans. All of the mineral elements except zinc were significantly increased on germination. No obvious changes in the electrophoretic pattern of faba bean proteins were observed as the seeds were soaked for up to 12 h. Extending soaking time for a further 4 h led to the disappearance of one band at the region of MW 67 KD. Germination of seeds for 3 days initiated disappearance of some bands while other new bands were observed.     

Preparation of broad bean (Vicia faba L. minor) products Part 3. Pretreatment of broad beans and broad bean flour —processes and effects

For improving sensory, functional and other properties broad beans are pretreated in 3 different ways. The pretreatments include defatting or isoelectric washing of broad bean flour and hydrothermal treatment of whole dehulled broad beans. Every pretreatment process leads to particular advantages, described in this paper, although sensory improvements are found in all pretreated products.     

Effect of Processing on Certain Antinutrients in Cowpeas (Vigna unguiculata)

Four Nigerian cultivars of cowpeas were analyzed for raffinose, stachyose, phytic acid, tannins, and trypsin inhibitory activity after dehulling, cold-soaking, hot-soaking, and cooking as ewa-ibeji and moin-moin (two popular Nigerian cowpea foods). Dehulling decreased stachyose and removed the tannins. Hot-soaking caused a significant reduction in stachyose and trypsin inhibitory activity. Ewa-ibeji and moin-moin contained similar quantities of antinutrients, except for tannins which were absent in moin-moin.     

Effects of Germination, Dehulling and Cooking on the Nutritive Value of Cowpea (Vigna unguiculata) Flour

The effects of germination, dehulling and cooking on the nutritive value of cowpea flours supplemented with rice were studied in 20 adult rats. The 70:30 (protein basis) combinations of cowpea flours and rice provided 1.6g N/100g diet for the 12-day balance study. Mixtures of whole, ungerminated, and uncooked beans (WUUB) and rice and whole, germinated and cooked beans (WGGB) and rice increased in seven of the parameters tested more than those of dehulled, ungerminated and uncooked beans and rice or dehulled, germinated, uncooked beans (DGUB) and rice. The DGUB and rice mixture produced higher positive calcium and magnesium balances than the WUUB and rice or the WGGB and rice mixtures. Germination and cooking appeared to be the best processing methods to provide nutritious foods based on cowpea in rats.     

COOKING CHARACTERISTICS OF FOUR CULTIVARS OF BAMBARA GROUNDNUTS SEEDS AND STARCH ISOLATE

The proximate composition and textural changes during the cooking of four bambara groundnut (Voandzeia subterranea) seed cultivars were evaluated. Bambara groundnut seeds contained 18–21% protein 6–8% fat, 8–10% moisture and 1.2–2.6% ash. Changes in hardness in relation to cooking time was monitored for 2 h. The cooking time for softening was shorter for the cream and brown colored cultivars than for the red black colored cultivars. The swelling and viscosity properties of starch isolates prepared form the seeds were studied. There were no varietal differences (p≤0.05) in starch viscosity and swelling properties among cultivars. Estimation of tannin content of bambara groundnut seeds showed that tannin contents of the red and black seed cultivars (0.96% and 1.1%, respectively) were significantly higher (p≤0.05) than the tannin contents of cream and brown seed cultivars (0.68% and 0.72%, respectively).     

In-vitro multienzyme digestibility of protein of some plant source flours blended with bovine plasma protein concentrate

The in-vitro multienzyme protein digestibilities of the flours of maize, cassava, pigeon pea (Cajanus cajan), African yambean (Sphenostylis stenocarpa) and bambara groundnut (Vigna subterranea), blended with bovine plasma protein concentrate were investigated. The multienzyme system consists of trypsin, chymotrypsin and peptidase. It was found that the addition of bovine plasma protein concentrate improved the protein digestibility of the flours compared with flours without the additive. The digestibilities were increased by between 3% in bambara groundnut blended flour to about 10% in cassava blended flour. When the flours were wet-heat treated, the digestibilities further increased in all samples with increments between 7·5 % in bambara groundnut and 16·6% in cassava flour. Bovine plasma protein concentrate may be a good source of protein for the fortification of protein-deficient foods, particularly maize and cassava flours.