Effects of various water or hydrothermal treatments on certain antinutritional compounds in the seeds of the tribal pulse,Dolichos lablab var.vulgaris L.

Effects of soaking, cooking and autoclaving on changes in polyphenols, phytohaemagglutinating activity, phytic acid, hydrogen cyanide (HCN), oligosaccharides and in vitro protein digestibility were investigated in seeds ofDolichos lablab var.vulgaris. Both distilled water and NaHCO₃ solution soaking and autoclaving significantly reduced the contents of total free phenolics (85–88%) compared to raw seeds. Autoclaving (45 min) reduced the content of tannins by upto 72%. Soaking seemed to have limited effect in eliminating phytohaemagglutinating activity, whereas autoclaving (45 min) seemed to eliminate the haemagglutinating activity completely. The reduction in content of phytic acid was found to be some what greater in distilled water soaking (28%) compared to NaHCO₃ solution soaking (22%). Only a limited loss in content of phytic acid was observed under cooking as well as autoclaving. Loss of HCN was greater under autoclaving (87%) compared to the other processes studied. Of the three sugars analysed, soaking reduced the level of verbascose more than that of stachyose and raffinose. Autoclaving reduced the content of oligosaccharides more efficiently (67–86%) than ordinary cooking (53–76%). Autoclaving improved the in vitro protein digestibility (IVPD) significantly (13%). Of all the different water and hydrothermal treatments studied autoclaving seemed to be the most efficient method in improving IVPD and eliminating the antinutrients investigated except phytic acid.     

Oligosaccharins of Black Gram (<Emphasis Type="Bold">Vigna mungo</Emphasis> L.) as Affected by Processing Methods

The oligosaccharide content was determined in 12 different cultivars of black gram. The effect of various treatments such as soaking, cooking, and enzyme treatment on the raffinose family oligosaccharides of dry seeds and flour was studied. Ajugose, a higher oligosaccharide (DP 6) found in trace quantities in seeds, was shown in black gram by HPLC. The percent reduction of raffinose, stachyose, verbascose, and ajugose after soaking for 16 hr was 41.66%, 47.61%, 28.48%, and 26.82%, respectively in Local-I variety and 43.75%, 20.58%, 23.60%, and 15.88%, respectively in Local-II variety. Cooking for 60 min resulted in decrease of 100% for raffinose, 76.19% for stachyose, 36.39% for verbascose, and 60.97% for ajugose in Local-I variety and 100% for raffinose, 55.88% for stachyose, 48.52% for verbascose, and 56.07% for ajugose in Local-II variety. Thin layer chromatographic analysis of 3 hr enzyme-treated samples revealed almost complete hydrolysis of raffinose family of oligosaccharides. Among the different methods employed, enzyme treatment was found to be the most effective for removing α-galactosides in black gram.     

Effect of soaking,cooking and germination on the oligosaccharide content of selected Nigerian legume seeds

The identity and quantity of and effect ofprocessing on raffinose oligosaccharides in raw,mature seeds of lima beans (Phaseolus lunatus),pigeon peas (Cajanus cajan), African yam beans(Sphenostylis sternocarpa) and jackbeans (Canavalia ensiformis) were investigated. Sucrose,raffinose, stachyose and verbascose were identified byHPLC in all the legume seeds. The total-galactoside contents of the seeds in decreasing order were African yam beans3.84 mg/100 mg; white lima beans 3.62 mg/100 mg; creampigeon peas 3.51 mg/100 mg; red lima beans3.37 mg/100 mg; jackbeans 2.83 mg/100 mg and brownpigeon peas 2.34 mg/100 mg. The predominantoligosaccharide was verbascose in pigeon peas andstachyose in the other three legumes. Cooking unsoakedseeds brought about a greater reduction in the total-galactoside content than soaking for ninehours. The removal of oligosaccharides was higher inlegumes cooked in alkaline solution than in water.Germination quantitatively reduced raffinose,stachyose and verbascose while sucrose was increasedin all seeds except red lima beans and jackbeans.     

Effect of domestic processing,cooking and germination on the trypsin inhibitor activity and tannin content of faba bean (Vicia faba)

The effects of domestic processing methods like soaking for 12 h dehulling, ordinary cooking of whole as well as dehulled seeds at 151bs/inch² pressure for 15 and 25 min, and germination for 24, 36 and 48 h were observed on trypsin inhibitor (TIA) and tannin content of two varieties of faba bean viz. VH-131 and WF. A non-significant reduction in TIA was observed on soaking and dehulling, while tannins showed a reduction of 42 and 51% on soaking in VH 131 and WF, respectively. Dehulled seeds showed a decline in tannin content by 70 to 73% in two varieties. There was a significant reduction in TIA (75–76 per cent) and tannin (76–81%) on cooking, while autoclaving for 25 min almost completely eliminated both of these stress factors. Germination of seeds for 48 h led to a reduction of 64–65% in TIA and 90–91% in tannins, which was more than germination for 24 and 36 h. Soaked seeds gave positive results of both these antinutrients.     

Quality attributes of three new improved lines of Nigerian lima beans (Phaseolus lunatus L. Walp.)

Three promising new improved lines of lima beans (Tpl 1^B, Tpl 7^A and Tpl 175^A) were evaluated for physicochemical properties and cooking quality. The beans varied in seed dimensions and weights with Tpl 1^B and Tpl 7^A having smaller seed volume than Tpl 175^A. Seed coat percentages, leached solids and swelling capacities were within a range of 10.2–19.6% (w/w), 0.44–0.92 g/100 g and 94.0–121.0 g/100 g dry bean, respectively. Cooking times varied between 62 and 81 min without soaking and were reduced by about 34%following a presoaking treatment in water for 12 h at room temperature (28 ± 1 °C). Small seeds absorbed higher amounts of water during soaking and required more cooking time than larger seeds. No significant (p>0.05) difference in cooked texture was found between unsoaked beans cooked for 50 min and soaked beans cooked for 30 min,suggesting that cooking times and cooked texture for all lines were improved through soaking.     

Chemical and sensory evaluation of vegetable milks from African yam bean Sphenostylis stenocarpa (Hochst ex A Rich) Harms and maize (Zea mays L.)

Vegetable milks were developed from fermented and unfermented African yam bean (AYB) flours and their maize blends. AYB was cleaned, dehulled, milled and fermented for 24 hours by the natural microflora present in the legume flour. Maize was fermented for 48 hours. A ratio of 70:30 (protein basis) of AYB: maize was used to formulate the blends. Vegetable milks were prepared from the AYB flours and their maize blends. Standard assay techniques were used to evaluate the milks for proximate, mineral, ascorbate and antinutrient composition. The protein contents of the milks (1.47–2.06 percent) was comparable to soymilk (2.04 percent) and bambara groundnut milk (2.00 percent). The milks contained appreciable quantities of carbohydrate and minerals tested. The milk blends had traces of ascorbate and contained higher phosphorus than the milks from the AYB flours. The fermented milk blend had higher protein, ash and sugar levels and lower phytate and stachyose levels compared to non-fermented blend. Raffinose was reduced to trace levels in the fermented milks. The milks were appetizing. The fermented milk blend was more acceptable than others and was preferred in terms of flavor and color. It had greater advantages over the other vegetable milks evaluated in terms of zinc, phosphorus and stachyose levels.     

Oligosaccharides in several Philippine indigenous food legumes: Determination,localization and removal

The oligosaccharide profile of raw mature seeds of seven different legumes indigenous to the Philippines was measured in 70% ethanol extracts of the seeds by thin layer chromatography using HPTLC plates and quantified by a densitometer. Based on the results, the legumes could be ranked according to decreasing oligosaccharide content or flatulence potential as follows: Sam-samping (Clitoria ternatea)>hyacinth bean (Dolichos lablab)> sabawel (Mucuna pruriens)>lima bean (Phaseolus lunatus)>swordbean (Canavalia gladiata)>rice bean (Vigna umbellata)>jack bean (Canavalia ensiformis). Sam-samping had 4.79% total oligosaccharides and hyacinth bean or batao, 3.66%. A jack bean accession had 1.79% oligosaccharides.Simple processing methods were tested to detoxify the oligosaccharides. Soaking the batao seeds had no effect while boiling even resulted in a net 23–31% increase in the levels of raffinose, stachyose and verbascose. On the other hand, two min of dry roasting resulted in complete removal of oligosaccharides whereas germination resulted in about 30–40% decrease after 1 and 2 days, respectively.Part of MS thesis of the senior author.     

Some biochemical and nutritional changes during the fermentation of fluted pumpkin (Telferia occidentalis)

The pH, soluble nitrogen, soluble solids and titratable acidity increased during a 6 day fermentation of fluted pumpkin seeds. Gas liquid chromatographic analysis of trimethylsilyl (TMS) dirivatives of carbohydrates extracted from the seeds showed that the unfermented seeds contained mostly sucrose with a low content of flatus-oligosaccharides, raffinose and stachyose. There were also high contents of fructose and galactose. Fermentation increased the total monosaccharides with high content of glucose and some unidentified monosaccharides. Fermentation decreased the total oligosaccharide, eliminated raffinose and stachyose and increased the content of maltose. Except for a slight decrease in total saturated and increase in total unsaturated fatty acids, fermentation had no effect on fatty acid composition.     

Effect of domestic processing on the cooking time,nutrients, antinutrients andin vitro Protein digestibility of the African yambean (Sphenostylis stenocarpa)

The effects of processing (soaking, dehulling, fermentation and heat treatment) on the cooking time, protien, mineral, tannin, phytate and in vitro protein digestibility (IVPD) of the african yambean (AYB) were examined. The cooking time ranged from 90–155 minutes. Soaking reduced cooking time by about 50 percent. Soaking for 12 hours was the most appropriate to reduce cooking time, tannin and phytate levels. It improved in vitro protein digestibility (IVPD). Prolonged soaking (24 hours) decreased calcium (Ca) and iron (Fe) values by 19 percent and 35 percent, respectively. Dehulling showed that Ca, Fe, magnesium (Mg) and zinc (Zn) were concentrated in the seed coat of the AYB. The seeds soaked and dehulled retained Mg and Zn. Dehulling reduced tannin but had no significant effect on phytate and the IVPD of the AYB except for seeds soaked for 12 hours before dehulling. Soaking for 24 hours before dehulling significantly increased crude protein content by 16 percent (p<0.05). Blanching and roasting increased the IVPD by 8–11 percent. Fermentation had no effect on the crude protein, Ca, Fe, Mg and Zn but significantly reduced phytate content of the AYB. Fermentation had no advantage over heat treatment with respect to improving the in vitro protein digestibility of the AYB.     

Phytic acid in stored common bean seeds (Phaseolus vulgaris L.)

Four varieties of common bean seeds stored at 4°C, 80% relative humidity, for one to eight years showed no differences in proximal chemical composition, Seeds 5–6 years old absorbed more water than 1 to 4 year-old seeds. The cooking time required for five year-old seeds was 6 hours, while the fresh seeds needed 3/4-to-one hour cooking time. The most remarkable difference was in phytic acid content, which decreased 94% to 98% during long storage.     

Pretreatment of African Yam Bean (<Emphasis Type="Italic">Sphenostylis stenocarpa</Emphasis>): Effect of Soaking and Blanching on the Quality of African Yam Bean Seed

The effect of pretreatment (soaking in sodium salts and blanching) on hydration coefficient (HC), chemical composition, texture, and color of African yam bean (AYB) was investigated. Soaking in water and in salt solutions increased the HC and about 90% of final HC values were attained at 12 and 4 hr of soaking for whole and dehulled beans, respectively. Protein content was slightly increased by soaking and blanching while ash and fat contents were reduced. Generally, a combination of dehulling and wet-processing reduced firmness of the beans more than soaking or blanching of the whole beans. Antioxidant activity was lowest (3260 TE³100 g) in cream-colored beans and highest (16,600 TE/100 g) in brown-colored beans. The tannin contents of unprocessed cream-colored beans and dehulled wet-processed marble variety were not significantly different (p > 0.05). The levels of tannins in the marble variety were reduced by blanching for 40 min (19.2%), soaking for 12 hr (16.0%), dehulling (72.0%), dehulling and blanching (88.8%). The whiteness of bean flours was increased significantly by dehulling, slightly by wet-processing of marble variety, and reduced significantly by wet-processing of cream-colored beans. TE: micromole equivalents of Trolox (TE) per 100 g of a sample. L^∗ value value: determined by McBeth colorimeter (Minolta Co., Japan).     

Use of two varieties of hard-to-cook beans (Phaseolus vulgaris) and cowpeas (Vigna unguiculata) in the processing of koki (a steamed legume product)

Koki is a nutritious cowpea-based food product usually processed by steam cooking whipped cowpea (Vigna unguiculata) paste mixed with spices and palm oil. A study was carried out to investigate the effect of the partial replacement of cowpeas (CP) with hard-to-cook (HTC) beans on the chemical, nutritional and sensory characteristics of koki. Towards this objective, two varieties of beans – Phaseolus vulgaris (red kidney beans – RKB and mottled brown beans – MBB), each with the HTC defect, were separately incorporated into cowpea paste in the following Bean:CP ratios 0:100, 20:80, 30:70, 40:60, 50:50, 60:40 and processed into koki. Incorporation of dry HTC beans into cowpeas in the making of koki affected the bulking properties of the uncooked paste, the nutrient composition, essential amino acid content, antinutritional factors, digestibility as well as the sensory attributes of cooked koki. Sensory tests showed that a highly acceptable, nutritious and digestible koki can be processed from cowpeas partially replaced with dry HTC bean paste up to levels of about 40–50% depending on the variety of dry bean used.     

Effect of heat treatment on the proximate composition,energy values,and levels of some toxicants in African yam bean (Sphenostylis stenocarpa) seed varieties

The effects of heat treatments on the proximate composition, energy content, and levels of some antinutritional factors in brown and marble-colored African yam bean (AYB) seed flours were investigated. In raw brown and marble-colored AYB seed flours; moisture content, dry matter, crude protein, crude fat, ash, total carbohydrate and caloric value did not differ significantly at the 5% level. Autoclaving and cooking slightly increased the moisture level. Crude protein, crude fat, and ash contents were decreased by autoclaving and were further decreased by cooking. The decrease was not, however, considerable for the AYB that is not eaten raw and whose full nutritional potential as a legume can be derived only when heat treated, as previous reports have indicated for legume seeds.The levels of the toxicants were generally higher in the raw brown AYB compared to the marble-colored, and were generally reduced by both autoclaving and cooking. In the most commonly available and consumed marble-colored AYB, autoclaving at 121 ^°C, 15 psi for 20 min decreased cyanogenic glycosides by 46%, oxalate by 48.9%, tannin by 15.0%, saponin by 14.8% and trypsin inhibitors by 61.3% while cooking for 3.5 hours in tap water decreased these toxic factors by 66.5%, 70.3%, 72.2%, 48.7%, and 86.0%, respectively.The results indicate that for raw samples, varietal difference did not significantly affect nutrient composition though the toxicants were generally higher in the brown AYB than the marble-colored. Autoclaving decreased both nutrient value and the level of toxicants in the two seed types; values were further reduced by cooking. Of the toxicants, trypsin inhibitor was found to be the most heat-labile and of the heat treatment methods, cooking to tenderness is recommendable.     

Antinutrients in amphidiploids (black gram × mung bean): varietal differences and effect of domestic processing and cooking

Phytic acid, saponin and polyphenol contents in grains of various varieties of black gram (Vigna mungo) Mung bean (Vigna radiata L.) amphidiploids ranged from 697 to 750, 2746 to 2972 and 702 to 783 mg/100 g, respectively. Domestic processing and cooking methods including soaking, ordinary and pressure cooking of soaked and unsoaked seeds, and sprouting significantly lowered phytic acid, saponin and polyphenol contents of the amphidiploid seeds. Soaking for 18 h removed 31 to 37% of the phytic acid; the extent of removal was higher with long periods of soaking. Saponins and polyphenols were relatively less affected. Loss of the antinutrients was greater when soaked instead of unsoaked seeds were cooked. Pressure cooking had a greater effect than ordinary cooking. Antinutrient concentrations declined following sprouting; the longer the period of germination the greater was the reduction.     

Cultivar and processing effects on the pasting characteristics,tannin content and protein quality and digestibility of cowpea (Vigna unguiculata)

Four popular West African local cultivars of cowpea (Vigna unguiculata), with distinctly different seed coat colors, were evaluated for their relative amylograph pasting characteristics, condensed tannin content, in vitro protein digestibility and Tetrahymena protein efficiency ratio (t-PER). The effects of roasting and dehulling on these properties were also determined. There were wide variations in the hot paste viscosity characteristics of the different cultivars studied. The raw cowpea flour samples exhibited maximum paste viscosities ranging between 260 Brabender Units (BU) for the Mottled cultivar and 460 BU for the cream-colored Blackeye cultivar. Cowpea cultivars with the greatest peak viscosities showed low stabilities to extended cooking. Roasting depressed paste viscosity properties of all the cowpea cultivars studied. Tannin concentrations were 0.3–6.9 and 7.2–116 mg CE/g flour from whole cowpea seeds and seed coats respectively, increasing with intensity of seed color. Although dehulling removed 98% of the tannin content of raw cowpeas, improvement in protein quality as a result of dehulling was observed for only the highly-pigmented Maroon-red variety. Roasting significantly improved digestibility and more than doubled the t-PER of all cowpea cultivars studied. Roasted cowpeas possess adequate nutritional and functional qualities as protein supplements in cereal-based weaning foods. However, it appears that dehulling is necessary to enhance the nutritional quality of the highly pigmented cultivars of cowpea.     

Influence of hardening procedure and soaking solution on cooking quality of common beans

Two common bean (Phaseolus vulgaris) varieties were seeded in the same location, harvested and cleaned. Three hardening procedures were used (soaking in acetate buffer, pH 4.1 at 37°C for 5 h; storage at 37°C, 100% RH for 28 days; and storage at 31–33°C, 76% RH for 120 days) to have seeds in a hard-to-cook (HTC) state. The adverse effects of HTC condition, in terms of cooking time as assessed by a Mattson bean cooker, were practically eliminated by soaking seeds in salt solutions (1% NaCl+0.75% NaHCO₃; and 0.75% NaHCO₃) instead of only water. Ultrastructural changes of cotyledon cells from fresh, HTC and softened seeds were observed. Results of this study may be used for the development of a technological procedure to utilize properly HTC beans generated by unefficient storage systems.     

Evaluation of selected food characteristics of three advanced lines of Nigerian soybean (Glycine max (L.) Merr.)

The seeds of three promising advanced lines of soybeans (TGx 923-2^EN, TGx 1019-2^EN and TGx 1497-1^D) which were part of a larger collection evaluated in agronomic field trials in Nigeria were selected for characterization of physicochemical properties, chemical composition, water absorption, cooking time and cooked texture as a function of soaking and cooking. Seed density, leached solids, swelling capacity and seed coat percentage were within a range of 1.15 to 1.26 g per ml, 1.00 to 1.26 g per 100 g, 80.25 to 84.35 g per 100 g and 6.6 to 10.1% w/w of dry beans, respectively. The total polyphenol content of the cream colored beans was similar (0.75 to 0.76 mg/g) but higher than the amount (0.60 mg/g) found in the white beans. Cooking times varied between 71 and 96 min without soaking and were reduced by about 32.0% following a presoaking treatment in water for 12 hours at room temperature (28±1°C). Small seeds absorbed higher amounts of water during soaking and required less cooking time than larger seeds. Unsoaked beans required 40 min of cooking to achieve the same degree of cooked texture as the soaked beans cooked for 20 min, suggesting that cooking times and cooked texture for all lines were improved through soaking.     

Amino acid composition protein quality and water-soluble vitamin content of germinated cowpeas (Vigna unguiculata)

Amino acid composition, protein digestibility, calculated protein efficiency ratio (C-PER and DC-PER), chemical scores and water-soluble vitamin content of cowpea seeds germinated at 25°C or 30°C for 24h were determined. Also, the effect of processing steps (heated-air drying, decortication and cooking) on these parameters were examined. Germination had little effect on amino acid profile of cowpeas. In vitro protein digestibility was not improved significantly by germination nor by decortication but was improved by cooking. C-PER and DC-PER ranged from 1.95 to 2.21 and from 1.63 to 1.82, respectively. DC-PER compared well withreported rat PER of cowpea products and seemed more sensitive than C-PER. Based on whole egg values, chemical scores ranged from 37.7 to 45.8% (mean±SD; 42.2±2.4%). Germination increased the contents of niacin, thiamin and riboflavin significantly. Decortication resulted in up to 30% loss in niacin while thiamin content was reduced 41% by cooking.     

Carbohydrate changes in fermenting locust bean (Parkia filicoidea) duringiru preparation

Oligosaccharides were the most abundant carbohydrates in the unfermented African locust beans. Flatus-forming oligosaccharides — stachyose, raffinose and sucrose — were the main constituents. During the first 24 h of fermentation, the quantities of the oligosaccharides decreased significantly. The reducing sugars increased during the first 12 h of fermentation but then decreased. The reducing sugars detected in the unfermented and fermented locust beans were similar; these were galactose, glucose and fructose. The activities of α-galactosidase were highest at 24 h from the start of fermentation while the peak of sucrose activity was at 36 h.     

The effects of sprouting times on nutritive value of two varieties of african yam bean (sphenostylis stenocarpa)

Forty-eight rats (80–125 g) were used to determine the nutritive value of two sprouted varieties of African yam bean. The cream and brown varieties were each sprouted for 36, 48 and 72 h and blended with corn in a 70:30 ratio (protein basis) to provide 1.6 g N/100 g diet for the entire study period. Sprouting for 48 h caused an increase in most of the parameters tested for both varieties. Sprouting increased natural enhancement of nutrients.