Wisdom A. Plahar

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.

Development of an integrated quality assurance system for the traditional Sardinella sp. and anchovy fish smoking industry in Ghana

Abstract The physical, chemical, microbiological, sensory and toxicological quality implications of all the operations involved in handling, processing and storage of traditional smoked sardinella sp. and anchovy production in Ghana were evaluated. The results were used to assess the potential hazards in the traditional smoked fish production chain and to identify critical control points for the development of an integrated quality assurance system. A wide range of quality characteristics was observed for products from different processing sites due to lack of a standardized technique. Potential safety and spoilage hazards identified include contamination of raw, processed, and stored fish with pathogenic bacteria, spoilage microorganisms, biogenic amines, insect infestation, as well as possible excessive deposition of wood smoke chemicals. Spoilage microorganisms and insect infestation, however, were found to constitute a high risk in terms of product loss, but low severity of the hazard. Critical control points identified include raw fish quality and handling from landing to processing site, time and temperature controls during handling and processing, fuel wood type, smoking rate and duration, storage conditions and general hygiene and sanitation procedures. Critical limits have been established for each processing and storage step to ensure that microbiological, chemical and sensory quality characteristics are satisfied. An effective monitoring procedure has been suggested.

Effect of soy-fortification method on the fermentation characteristics and nutritional quality of fermented maize meal

Studies were conducted to develop an appropriate household/small-scale enterprise level technique for the production of soy-fortified fermented maize dough (or meal) by comparing different treatments, processing methods and fortification levels. The effects of fortification method of the Ghanaian traditional fermented maize dough with raw or heat-treated whole soybeans and full-fat soyflour at 0%, 10% and 20% replacement levels, on the rate of fermentation and product quality were investigated. Sensory characteristics, trypsin inhibitor activity, amino acid pattern, proximate composition and hot paste viscosity were used as the indices of quality. Addition of whole soybeans to maize before milling and fermentation reduced the fermentation time by 60% while increasing the protein content by 24% and 70% respectively for 10% and 20% levels of fortification. A significant improvement was also achieved in the amino acids pattern of the fortified dough. However, raw whole soybeans imparted an undesirable color and beany flavor and an appreciable concentration of trypsin inhibitor activity (TIA) to the dough. Boiling soybeans for 20 min before incorporation into the maize for milling and fermentation was found necessary for desirable flavor and low levels of TIA. Little or no changes in the pasting viscosity characteristics occurred in samples containing boiled soybeans, while the usual method of fortifying maize meal with soy flour was found to severely depress the pasting viscosity characteristics and drastically reduced the acidity of the fermented dough. Based on the findings of the study, the most appropriate technique for the production of soy-fortified high protein fermented maize dough has been suggested to involve incorporation of boiled whole soybeans in soaked maize before milling and fermentation for improved sensory characteristics, enhanced nutritive value and optimal functional properties.

Cowpea inhibition of human and bovine protease activities and the effects of processing

The inhibition of human and bovine pancreatic trypsin, chymotrypsin and total proteolytic activity of extracts from the red cowpea was studied. The thermal lability of the inhibitors was also assessed. The raw cowpea samples used had a trypsin inhibitor activity (TIA) level of 14.3 mg trypsin inhibited/g sample. Inhibition of proteolytic activity was influenced by the type and source of pancreatic enzymes. At all levels of raw cowpea extract concentration, bovine trypsin was inhibited to a significantly greater extent (P < 0.05) than was human trypsin. The most drastic inhibitory effects of raw cowpea was, however, observed in hydrolytic systems containing human chymotrypsin. The action of cowpea inhibitors was less pronounced (maximum of 50% inhibition) on total proteolytic activity compared to individual inhibitions of trypsin and chymotrypsin. With regards to processing effects, almost complete inactivation of inhibitors was achieved by cooking whole cowpea seeds after soaking and dehulling, while only partial inactivation occurred when raw cowpea was milled into flour before cooking. Effective control of the inhibitory activities in cowpea for maximum nutritional benefits can therefore be achieved by soaking, dehulling and cooking whole cowpea seeds.

Effect of soybean fortification on Ghanaian fermented maize dough aroma.

The effect of soy fortification on the development of aroma compounds, dough acidity and growth of the predominant microorganisms were investigated in Ghanaian maize dough fermented spontaneously over a period of 72 h. The fortified maize dough was prepared from a milled mixture of soaked maize grains and pre-soaked, blanched and dehulled soybeans added at 20% replacement level. Extracts of volatiles from the soy-fortified and unfortified dough samples were obtained by Likens–Nickerson simultaneous distillation and extraction method analysed by gas chromatography-mass spectrometry and gas chromatography-olfactometry (gas chromatography-sniffing). Major aroma compound groups identified in the fermented dough samples were carbonyls, alcohols, esters and volatile organic acids. Twenty-nine carbonyls were found in soy-fortified maize dough compared with 21 in the unfortified dough. Although the same alcohols were found in both dough samples, the total concentration of alcohols was slightly different, being less for the soy-fortified sample. Total concentration of esters in soy-fortified dough decreased after 72 h while levels in the unfortified dough increased. Increases in the production of lactic and acetic acids occurred in soy-fortified samples, but the maximum concentrations of acetic acid achieved did not differ significantly between the two types of dough. Twenty-three compounds were perceived to be contributing to the typical aroma of soy-fortified maize dough by the method of gas chromatography-sniffing. These included 12 carbonyls, six alcohols, two esters, two acids and one furan.

Development and quality characteristics of shelf-stable soy-agushie: a residual by-product of soymilk production

Abstract A process was developed for the production of a high‐protein food ingredient, soy‐agushie, from the residual by‐product of soymilk production. The product, with a moisture content of about 6%, was evaluated for its quality characteristics and performance in traditional dishes. The protein content was about 26% with similar amino acids content as that of the whole soybean. Lysine remained high in the dehydrated product (6.57 g/16 g N). While over 60% of the original B vitamins content in the beans was extracted with the milk, high proportions of the minerals were found to be retained in the residual by‐product. The process adequately reduced the trypsin inhibitor levels in the beans from 25 to 1.5 mg/g. High sensory scores were obtained for recipes developed with soy‐agushie in traditional dishes. The scope of utilization of the soy‐agushie could be widened to include several traditional foods and bakery products for maximum nutritional benefits.

Bambara Marketing Margins Analysis in Ghana

The study identified the distribution channels for bambara by tracing the movement of bambara grain from the producing centres to the consuming centres, examined the socio-economic background of producers and traders in the marketing system and analyzed bambara marketing margins using data on prices at the various levels of the distribution channel. The results indicated that approximately 35 per cent of volumes of bambara produced were utilized by the producerhouseholds either as food and, for seed. Pricing was based largely on negotiation bargaining power, rather than the true value of the product, and the position of the producer in price formation was weak. The total gross marketing margin ((TGMM) for bambara was estimated at 41.66 per cent with producer participation margin (PPM) of 58.34 per cent. Total marketing charges was approximately 11 per cent of the retail price.