Ogugua C. Aworh

Effect of soaking, dehulling, cooking and fermentation with Rhizopus oligosporus on the oligosaccharides, trypsin inhibitor, phytic acid and tannins of soybean (Glycine max Merr.), cowpea (Vigna unguiculata L. Walp) and groundbean (Macrotyloma geocarpa Harms)

Abstract Soybean, cowpea and groundbean, three locally grown legumes in West Africa, were processed into tempe, an Indonesian-type fermented food. Changes in oligosaccharides, trypsin inhibitor, phytic acid and tannins were monitored during the pretreatments (soaking and soaking–dehulling–washing–cooking) and fermentation with Rhizopus oligosporus. About 50% of raffinose and more than 55–60% of sucrose and stachyose were lost during the pretreatments of the beans. Stachyose decreased during fermentation with a reduction of 83.9%, 91.5% and 85.5% respectively for soybean, cowpea and groundbean while raffinose remained fairly constant. Galactose, the predominant sugar, glucose, fructose, maltose and melibiose increased during the first 30 and 36 h of fermentation of cowpea and groundbean, but decreased thereafter. Soaking the beans for 12–14 h had no effect on the level of trypsin inhibitor of the beans while it increased the phytic acid content to 1.7% in soybean and to 0.8% and 0.7% in groundbean and cowpea. Cooking soaked and dehulled soybean, cowpea and groundbean for 30, 7 and 15 min respectively resulted in 82.2%, 86.6% and 76.2% in trypsin inhibitor. However, a slight increase in trypsin inhibitor was observed during soybean fermentation. Phytic acid decreased during fermentation by 30.7%, 32.6% and 29.1% respectively in soybean, cowpea and groundbean at the harvesting time. Tannins mainly located in seed coat were removed as a result of pretreatments mainly dehulling. These changes are beneficial especially in infant feeding based on cereal and legume-based foods.

Cheese-making properties of vegetable rennet from sodom apple (Calotropis procera)

Abstract Yield, chemical composition and texture profile of cheese made with vegetable rennet from sodom apple leaves were compared with those of a direct acid cheese made with calf rennet. Yield, moisture, fat and protein contents were 14·47%, 49·70%, 26·15% and 20·0%, respectively, for cheese made with vegetable rennet and 12·45%, 44·80%, 29·84% and 20·4%, respectively, for the direct acid cheese made with calf rennet. Cheese made with vegetable rennet had less soluble nitrogen than that made with calf rennet despite the fact that vegetable rennet was more proteolytic in casein solution than calf rennet. Relative to that made with calf rennet, cheese made with vegetable rennet was harder, less cohesive and more gummy, presumably because of differences in chemical composition and physical characteristics between the cheeses.

Preservation of West African soft cheese by chemical treatment

The effects of sorbic and propionic acids on shelf life and organoleptic characteristics of West African soft cheese stored at 7–9 °C were investigated. In cheeses treated with 0·1% sorbic acid spoilage was delayed and microbial growth, especially mesophilic bacteria, yeasts and moulds, was suppressed compared with untreated controls. Treatment with 0·05% sorbic acid or up to 10% propionic acid was less effective. An objectionable bitter flavour was reported for sorbate-treated cheese but other qualities were not adversely affected.

Developing GM super cassava for improved health and food security: future challenges in Africa

BackgroundThere is an urgent need to solve the problem of micronutrient malnutrition that is prevalent among young children and women in Africa. Genetically modified (GM) biofortified cassava has great potential to solve part of this problem, but controversy surrounding GM technology and lack of awareness, limited facilities, biased news and other factors may hinder the adoption of GM cassava in the future.MethodUsing semi-structured interviews in Ghana and Nigeria, this paper examines the perspectives of scientists, including the BioCassava Plus (BC+) team, on the potential adoption of GM cassava for improving health and food security in Africa. The article also examines issues around the regulatory system and transfer and acceptance of GM cassava among scientists.Results and discussionThe result suggests that an overwhelming majority of scientists agree that GM biofortified cassava will benefit the health of millions in Africa, and that GM cassava conferred with disease and pest resistance will increase cassava production as it is currently plagued by cassava mosaic diseases (CMD). However, respondents are wary of long-term effects of GM cassava on the environment and lack of a regulatory framework to facilitate the adoption of GM cassava. Even though scientists expressed little or no concern about health risks of GM cassava, they were concerned that consumers may express such concerns given limited understanding of GM technology.ConclusionThe article concludes with a summary of priorities for policy development with regard to adopting biofortified food products.

Post-harvest treatment of wild mango (Irvingia gabonensis) for improved shelf life

Abstract The effectiveness of hot water, chemicals, wax and film packaging in extending the post-harvest life of wild mango under tropical ambient conditions was investigated. Dipping wild mangoes in hot (55°C) water or hot 0·1% benomyl, 0·5% sodium dehydroacetate or 0·5% Na 2 S 2 O 5 , followed by waxing or packaging in boxes overwrapped with stretch PVC film, delayed ripening, controlled decay, minimised weight loss and extended the shelf life of the fruits when held at 22–35°C and 70–95% relative humidity without adverse effects on visual and chemical qualities. The best results were obtained when PVC film packaging was preceded by a sulphite dip.

Chemical and functional properties of cassava starch, durum wheat semolina flour, and their blends.

High-quality cassava starch (HQCS) produced from high-yielding low-cyanide improved cassava variety, TMS 30572, was mixed with durum wheat semolina (DWS) on a replacement basis to produce flour samples containing 0, 20, 30, 50, 70, and 100% cassava starch. They were analyzed for chemical composition (proximate, amylose, free sugars, starch, wet gluten, and cyanide) and functional properties (pasting, swelling power, solubility, water absorption, water binding, starch damage, diastatic and α-amylase activity, dough mixing, and stability). Protein, carbohydrate, fat, and ash of flour samples ranged from 0.75–12.31%, 70.87–87.80%, 0.95–4.41%, and 0.12–0.83%, respectively. Cyanide levels in all the flour samples were less than 0.1 ppm. Amylose content varied between 19.49% for cassava and 28.19% for wheat, correlating significantly with protein (r = 0.95, P = 0.004) and ash contents (r = 0.92, P = 0.01) at 5%. DWS and HQCS had similar pasting temperatures (50.2–53°C), while other pasting properties increased with increasing levels of HQCS. Dough mixing stability of samples decreased with increasing levels of HQCS. All the flour samples had α-amylase activity greater than 200. Both HQCS and DWS compare favorably well in swelling power (7.80–9.01%); but the solubility of wheat starch doubled that of cassava. Starch damage varied between 3.3 and 7.2 AACC for semolina and starch, with the latter having higher absorption rate (97%), and the former, higher absorption speed (67 sec). Results obtained showed positive insight into cassava–wheat blend characteristics. Data thus generated provide additional opportunities of exploiting cassava utilization and hence boost its value–addition potentials for product development.

Laboratory trials on bleaching palm oil with selected acid-activated Nigerian clays

Abstract The optimum conditions for acid activation of some selected Nigerian clays were determined. The bleaching potential of the activated clays on crude palm oil relative to a commercial Fullers earth (Fulmont 700C) were assessed. Bleaching activity was highest when 1 part of clay of particle size μ m was mixed with 3 parts of 1·4–2·7 m HCl or 0·5–1·0 m H 2 SO 4 , refluxed for 2–6 h, dried to between 5–15% moisture content, milled and sifted to obtain a particle size of μ m. Clays from Ewekoro and Shagamu in southern Nigeria, when properly activated using the wet slurry method, compared favorably with the commercial Fullers earth in bleaching activity. The Nigerian clays, however, showed lower apparent bulk densities and, consequently, a corresponding higher oil retention.

Purification and some properties of sodom-apple latex proteinases

Abstract Two thiol-activated proteinases with isoelectric points (pIs approximately 9–9·5) were purified from sodom-apple latex by chromatography on Q-Sepharose and Superdex 200. Proteinase I had an estimated molecular weight of approximately 25 000 and proteinase II one of about 30 000. The proteinases degraded casein and azocoll, proteinase I having a lower specific activity than proteinase II. Proteinase I was most active at pH 8–10, with the optimum at about pH 8. Proteinase II was most active at pH 6–8, with the optimum at about pH 7.

Effects of sodium benzoate on storage stability of previously improved beverage from tamarind (Tamarindus indica L.)

The effect of sodium benzoate on the quality attributes of improved tamarind beverage during storage was investigated. Tamarind beverages were produced according to a previously reported improved method, with or without chemical preservatives (100 mg/100 mL sodium benzoate). Tamarind beverage produced according to traditional processing method served as the control. The tamarind beverages were stored for 4 months at room (29 ± 2°C) and refrigerated (4–10°C) temperatures. Samples were analyzed, at regular intervals, for chemical, sensory, and microbiological qualities. Appearance of coliforms or overall acceptability score of 5.9 was used as deterioration index. The control beverages deteriorated by 2nd and 10th days at room and refrigerated temperatures, respectively. Improved tamarind beverage produced without the inclusion of sodium benzoate was stable for 3 and 5 weeks at room and refrigerated temperatures, respectively. Sodium benzoate extended the shelf life of the improved tamarind beverage to 6 and 13 weeks, respectively, at room and refrigerated temperatures.

Substitution of wheat with cassava starch: Effect on dough behaviour and quality characteristics of macaroni noodles

Purpose This paper aims to examine the effects of substituting durum wheat semolina (DWS) with high-quality cassava starch (HQCS) in macaroni noodle production. Design/methodology/approach The effect of substituting semolina with cassava starch in macaroni production at six levels, namely, 0, 20, 30, 50, 70, 100 per cent, and variation in hydration levels of 45, 50 and 55 per cent and their interaction were studied. Findings As substitution of DWS with HQCS increased from 0 to 50 per cent at 45 per cent hydration, amylose content increased from 15.91 to 22.79 per cent. However, beyond 50 per cent substitution level, the amylose content dropped significantly to 20.10 per cent. Yet, this reduction did not affect the extrusion ability of the doughs. Analysis of variance revealed that changes observed in the dough properties were not significant (p > 0.05). Research limitations/implications Trial productions of cassava macaroni noodles under factory processing conditions need to be explored. Also, cooking trials and consumer acceptability studies need to be conducted to pave the way for adoption by manufacturers. Practical implications Dried noodle products enjoy widespread popularity because of their shelf life, lower glycaemic indices, simplicity of preparation and moderate costs. This study showed the potential of substituting DWS with HQCS with no adverse effect on the dough and macaroni noodle characteristics. Social implications The adoption of the process described in this study would result in increased utilization of cassava, broaden existing food base and provide household food security for both rural and urban population. Originality/value This paper has shown the suitability of substituting DWS obtained from imported durum wheat, with HQCS: indigenous to Africa, for the economic benefit of macaroni manufacturers.