Dry milling characteristics of dried cassava chips as related to moisture content

No Abstract. Journal of Applied Science, Engineering and Technology Vol. 2(1) 2002: 13-1

Influence of Chemical Pretreatment on the Quality of Dried Whole Red Bell Pepper (Capsicum annuum var L)

Chemical pretreatment of vegetables prior to drying is widely used to improve colour, texture and overall acceptability. Thus, this study investigated the effect of chemical pretreatment on some physico-chemical properties, colour and rehydration properties of dried red bell pepper. Fresh samples of whole red bell peppers were soaked for 10 min in (0.3% (w/w) Potassium metabisulphite, 1% (w/w) Ascorbic acid, 1% (w/w) Calcium chloride, 0.3% (w/w) Potassium metabisulphite combined with 1% (w/w) Citric acid and 0.3% (w/w) Potassium metabisulphite combined with 1% (w/w) Calcium chloride) prior to drying. The results showed significant (p < 0.05) differences in all the qualities investigated. The values of vitamin C content, TSS and pH of the samples ranged from 39.22 to 72.2 mg/100g, 7.28 to 9.50 %, and 4.22 to 4.68, respectively. In terms of colour parameters, L*, a* and b* values ranged from 24.49 to 26.00, 38.34 to 55.20 and 27.47 to 30.96, respectively. The rehydration ratio and coefficient of rehydration ranged from 4.24 to 5.53, and 0.39 to 0.49, respectively. Dried whole red bell pepper soaked in 0.3% potassium metabisulphite combined with 1% calcium chloride prior to drying gave the most desirable colour and rehydration properties while the highest value of vitamin C was obtained in whole red pepper samples soaked in 1% ascorbic acid.Keywords: Pepper, pretreatment, physic-chemical, colour, rehydration propertie

Some thermo-physical properties of yam cuts of two geometries

The effects of variation of temperature (-18 to 33°C) and geometries (slab and cylinder) on some thermo-physical properties of white yam were investigated. The measured parameters were density, specific heat, and thermal diffusivity at constant moisture level of 72.7% ± 0.69 (wet basis) using transient heat transfer method. Both the density and specific heat of the sample increased with increase in temperature to maximum levels after which further increase led to a reduction of the values of these parameters; however, they were independent of sample’s geometry. The rate of heat diffusion per second for the yam as measured was between 2.365 to 11.86 x 10-8 m2 and 2.676 to 8.062 x 10-8 m2 for slab and cylinder respectively. The thermal diffusivity and computed thermal conductivity were found to increase with increase in temperature. Conclusively, these thermo-physical properties were correlated with temperature using polynomials of the third order empirical model