The maize-bambara groundnut foods had calcium, iron, zinc and vitamin A contents that satisfy the proposed nutrient requirements for infants. Only the maize-bambara groundnut and maize-bambara groundnut malt fermented by backslopping [(MB)(b) and (MB(m))(b)] containing red palm oil emulsified with Brachystegia eurycoma had calcium contents significantly (P < 0.05) higher than Nutrend, a complementary food produced by Nestle (Nigeria) PLC. These products are from raw materials produced in commercial quantities by rural farmers using household level technologies which the rural and urban poor can more easily access in order to reduce micronutrient malnutrition.

Polyphenol oxidase and peroxidase were puri®ed from white yam (Dioscorea rotundata) using DEAE-cellulose ionexchange chromatography. Thermoinactivation curves for polyphenol oxidase showed monophasic kinetics, while those for peroxidase were biphasic. Urea partially stabilised peroxidase against irreversible thermoinactivation, but did not do so in the case of polyphenol oxidase. Only peroxidase was capable of regenerating activity after thermoinactivation. The results showed that thermoinactivation of peroxidase was mainly due to conformational changes, while that of polyphenol oxidase was probably due to covalent damage. Peroxidase reactivation might play an important role in the browning of processed yam. INTRODUCTIONDespite the importance of yam as a major food crop in West Africa, its postharvest biochemistry has been poorly studied. 1 As a consequence, postharvest losses due to sprouting, physical damage, pests and pathogens have remained relatively high. 2 One relatively successful procedure for improving the postharvest storage of white yam (Dioscorea rotundata) tubers involves processing into¯our. This consists of (1) peeling off the outer covering, (2) cubing, (3) boiling in distilled water for 10±15 min, (4) drying and (5) milling into¯our. Unfortunately, consumer acceptability and the shelf-life of the¯our are adversely affected by the inability of the¯our to retain the typical white colour of yam which is highly desired by consumers. 3,4 Colour changes in freshly damaged plant materials have been attributed to the activity of polyphenol oxidase (PPO; o-diphenol:O 2 oxidoreductase, EC 1.10.3.2), which catalyses the oxidation of polyphenols to o-quinones. 5,6 Peroxidase (Px; donor: hydrogen peroxide oxidoreductase, EC 1.11.1.7) catalyses the oxidation of a number of aromatic compounds and has been associated with darkening in fresh and processed vegetables and fruits. 7 Both PPO and Px are known to be highly heat-resistant but each displays a different capability for reactivation after thermoinactivation. 5,8±11In D rotundata, which contains PPO, 3,4,12 correlating PPO activity with tissue browning was shown to be contraindicative. 13 The purpose of the present study was to relate the thermoinactivation processes of PPO and Px to the discolouration of processed yam.

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Background: Overweight and obesity in adolescence are powerful risk factors of chronic diseases in adulthood. Objective: To determine the prevalence of overweight, obesity and thinness among adolescents in rural and urban areas of Enugu State, Nigeria. Method: A total of 500 adolescents (10-19 years) consisting of 220 males and 280 females were randomly selected from 12 study schools in the State. A structured questionnaire was used to collect data on background information of the adolescents. Anthropometric measurements (weight and height) of the adolescents were obtained, and used to calculate the Body Mass Index (BMI). The BMI were categorized into obesity, overweight, normal and thinness using the International Obesity Task Force (IOTF) reference and the WHO adult BMI classification for adolescents up to 19 years. The data obtained were coded and analyzed into means, frequencies, percentages and chi-square using the Statistical Package for Social Sciences (SPSS), version 17. Results: The prevalence of overweight, obesity and thinness among adolescents were 7.5%. 2.1% and 13.9%, respectively. The prevalence of obesity among the adolescents in urban areas was 4.1% while none of the rural adolescents was obese. There was a higher prevalence rate of obesity among males than among females. Conclusion: Obesity is creeping into traditional societies as evident in this study.

Local red and white, and SK 5912 varieties of sorghum grains were malted, and assayed for amylase, diastatic and lipase activities. The 5-day malts from the red and white varieties were fermented for 48 h to produce burukutu, during which, lipase activities were monitored. Malt values peaked on day 5, and the red malts had the highest diastatic activities while the white variety had the lowest. Lipase activity in the malts peaked on day 4 with the red having the highest activity. The pH of the fermenting gruels decreased from 5.33 and 5.35 and levelled off at 3.88 and 3.85 for the red and white malts respectively. During fermentation, lipase activity peaks were detected at 0 h, 21 h and 45 h for the red malt with the highest peak at 45 h. The peak fermentation times for lipase activity in the white malt was at 0 h, 21 h and 48 h with the highest peak at 48 h. Lipase activity within the first 39 h was higher in the white gruel. Sorghum malt lipase from the red and white varieties may consist of three isoforms, two of which may have activity optima in the acidic pH range.

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Grain hardness using a hand-held tester is a simple, fast and good index of modification of malting red and white sorghum grains. Oven-dried red and white sorghum malts could be considered to be well modified at hardness values/indices below 77 N/0.5730 and 72 N/0.5036, respectively.