Effect of Soaking Water Temperature and Time on some Rehydration Characteristics and Nutrient Loss in Dried Bell Pepper

Sun-dried bell pepper was rehydrated at soaking water temperatures of 31°, 37°, 55°, 72° and 90°C, respectively. As the soaking water temperature increased from 31 to 72°C, rehydration ratio and coefficient of rehydration increased from 4.26 to 5.93 and 64.56 to 93.49 respectively while a further increase in soaking temperature to 900C, resulted in a decrease from 5.93 to 4.57 and from 93.49 to 75.77 respectively for the two parameters. At higher soaking water temperatures, larger amounts of vitamin C leached into the soaking water. However for Ca and Fe larger amounts were leached into the soaking water at lower soaking temperatures.

Modelling the Water Absorption Characteristics of Different Maize (Zea Mays L.) Types during Soaking

Water absorption characteristic of six different types of maize namely; dent corn (white and yellow), corn flour (white and yellow), popcorn and sweet corn during water soaking were studied at four different temperatures of 30, 40, 50 and 60 o C.The water absorption data fitted very well into both Peleg’s and Becker's models as to correspondingly determine the saturation moisture content (hydration equilibrium moisture content) and moisture diffusivity. The water absorption capacity and saturation moisture contents of each maize type increased as the water soaking temperature increased. The absorption kinetics followed the Fick's law of diffusion during the first hours of soaking. The determined diffusion coefficients values varied from 10.6 to 13.5 × 10-11 m2/s for sweet corn, 6.74 to 8.88 × 10-11 m2/s for white flour, 5.27 to 7.09 × 10-11 m2/s for yellow flour, 4.44 to 5.79× 10-11 m2/s for popcorn, 4.25 to 5.69 × 10-11 m2/s for dent white corn and 3.28 to 4.68 × 10-11 m2/s for dent yellow corn, respectively. An Arrhenius–type equation was used to relate the moisture diffusivity (diffusion coefficient) of dent corn (white and yellow), corn flour (white and yellow), popcorn and sweet corn to temperature, and the energy of activation for dent corn (white and yellow), corn flour (white and yellow), popcorn and sweet corn was estimated. The values determined were 8.17, 9.59, 7.83, 8.45, 6.61 and 8.01 kJ/mol for dent white corn, dent yellow corn, white corn flour, yellow corn flour, sweet corn and popcorn, respectively. Keywords: Maize varieties; Water absorption; Peleg’s model; Becker’s model; Arrhenius-type equatio

DEVELOPMENT OF A TRAY DRYER FOR FRUITS AND VEGETABLES USING ZIG-ZAG AIR FLOW CONFIGURATION

 Post harvest losses in fruits and vegetables in developing countries like Nigeria is high due to poor storage and processing facilities. The use of cabinet dryer for dehydration of fruits and vegetables to improve their shelf life has a drawback of non-uniformity in drying along the length of trays. Hence an effort was made to solve this problem by using a zigzag air flow pattern configuration. A cabinet dryer of capacity21kg/batch was designed and developed. The dryer was tested with okra slices using zigzag air flow pattern configuration. At an air flow rate of 8.8m3/s and 600c it took about 9 hours to reduce the moisture content from 79.55% (w.b) to 6.03%(w.b). Results obtained showed that drying of the okra slices took place in the falling rate period. The drying efficiency of the dryer was found to be 70%

NUTRITIONAL AND SENSORY QUALITIES OF SOYMILK- KUNNU BLENDS

Kunnu, a beverage popular among the Northern Nigerians has a low protein value because it is made from cereals. This may have a negative effect on the nutritional status of the people who drink it, especially on the growth rate of infants who are given kunnu as a weaning drink. This is because protein is an essential component of the balanced diet required for growth. Research work carried out on the improvement of the nutritional value of cereals, shows that the fortification of carbohydrate-rich foods with protein-rich foods improves its nutritious value. As a result of this, a study was carried out to fortify kunnu with soymilk and the effect on its nutritional and sensory properties was evaluated. Kunnu and soymilk were prepared and it was fortified with soymilk in the ratio 1:1, 2:1, 3:1 and 4:1, and the proximate composition (protein, fat, ash and moisture content), chemical composition (pH, specific gravity and sedimentation rate) and mineral content (calcium, magnesium, phosphorus and iron content) were determined. The pH, protein and mineral content increased as the amount of soymilk added. The pH value ranged from 4.8 to 4.3, while the protein content increased from 2.35 to 2.45%. The calcium and magnesium content also increased from 0.08 to 0.15% and 0.18 to 0.29% respectively. The fat and ash content, however, decreased respectively from 2.8 to 2.0, and 0.91 to 0.891 with an increase in addition of soymilk. The proximate, chemical and mineral content were significantly different at P < 0.05 while the sensory properties were not significantly different at the same level. The sensory properties (colour, taste, texture, flavor and general acceptability) were, however, observed to decrease with the increase in fortification level of soymilk. The results obtained show that the fortification of kunnu with soymilk will result in a more nutritious beverage, but it may have a low level of acceptance with the local populace

Development of Models for Predicting the Yield and Quality of Soymilk

Models were developed to predict the yield and quality of soymilk, one of soybean products. The quality characteristics investigated were total solids, protein content and fat content. The processing parameters considered were Amount of water added during grinding per Kg of dry seed, AW; Blanching time, BT and Heating time, HT. The models developed had coefficient of determination ranging from 0.78 to 0.99. Predicted values of the dependent variables compared quite well with the observed values when plotted against the independent variables. The predicted coefficients were also statistically significant (P< 0.05). Results showed that the yield and quality characteristics were affected by all the processing parameters. Hence, the production process must be effectively monitored to process soymilk of high yield and quality. J Food Tech in Africa (2002) 7, 55-5