Whole cowpeas were decorticated, adjusted to moisture contents of 20, 30 and 40%, chopped into coarse meals and extruded on a Wayne pilot-scale extrude1 (19 mm x 475 mm barrel, 5:l compression screw, 4.76 mm i.d. die) at barrel temperatures of 150", 175" and 2OO'C. Measured product temperatures ranged from 130-164'C. Product moistures ranged from lo-34% and were affected mainly by initial moisture. Expansion at the die was highest for 20% moisture extrudates (1.7-1.9), and lowest for 40% samples (0.9-1.3). The 20%-150" extrudate was dense (0.45 g/cm3) and twisted. The 20%-175" product was highly expanded (0.23 g/cm3). Other products were intermediate in density. Tristimulus color values were determined.

An extrusion capillary viscometer was employed to obtain shear stress-shear rate data of two types of cowpea pastes, traditional and experimental. The power law model was found to describe adequately flow behavior of the pastes with consistency coefficients of 77.45 and 59.02, and flow behavior indices of 0.456 and 0.458 for experimental and traditional pastes, respectively. Effect of hydration time (0 -180 min) and water level (54 -62%) on the apparent viscosity of experimental paste was determined by extrusion capillary and Brookfield viscometers with correlation coefficient of 0.953. Water level had a significantly greater effect than hydration time on apparent viscosity of cowpea paste.

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Samples of finely ground cowpea flour containing 7.5%, 19.4% and 25.5% moisture were heated in sealed tubes at 100") 125") and 150°C for periods of 0.5 to 120 min. First order rate constants for losses of trypsin inhibitor activity and nitrogen solubility ranged from 1 x IO-2 to 18 min-1 and from 4 x 10-Z to 8 min-I respectively. In vitro protein digestibility (IVD) increased, then decreased with heating as described by sequential first order kinetics. Rate constants for increase of IVDvaried from 0.13 to 12 min-I, while for decrease in IVD the range was 5 x 10-S to 3 x 10-Z min-I. Activation energies and relationships between In k and water activity were computed.

Effects of water level (56, 58 and 60%) and hydration time (0, 30, and 60 min) on apparent viscosity of cowpea paste and physical-sensory attributes of akara, a finished food made from paste, were determined. Water level had a greater effect than hydration time on paste viscosity and on crude fat content, shear force, lightness (L), and saturation index (AE) of akara. Apparent viscosity of cowpea paste was the only parameter significantly affected by the interaction of water level and hydration time. Overall, the 60% water level produced paste with flow properties and akara with physical characteristics most like the traditional product. Sensory attributes of meal-based products were acceptable.

An energy accounting method was used to determine energy consumption in various unit operations in canning tomato juice, whole‐peeled tomatoes, and tomato paste. Data on steam and electric consumption were obtained from a canning plant with the use of steam flow meters and electric transducers. Unit operations associated with the following equipment were investigated: crushers, hot‐break heaters, pulpers, finishers, lyebath peelers, evaporators and retorts. The average thermal and electrical energy intensities of canning to mato products were 538 Btu and 0.0126 kWh per pound of tomatoes received, respectively. Energy intensive operations were identified as those associated with hot‐break heaters, lyebath peelers, evaporators, and retorts.

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Experiments were done to determine the influence of temperature (21, 30 and 37°C) and aw (0.76 to 0.98) on aflatoxin production by Aspergillus flavus on cowpea (Vigna unguiculata) seeds, meal and meal supplemented with onion. Larger quantities of aflatoxin were produced at 21 and 30°C than at 37°C. The highest amount of aflatoxin (2777 μg/20 g, dry weight basis) was observed in meal containing onion at aw 0.98 after 20 d of incubation at 21°C. A level of 870 |μg/20 g was detected in seeds at aw 0.95 after 14 d of incubation at 30°C. Meal at aw 0.96 supported production of 551 μg of aflatoxin per 20 g after 20 d at 30° C. Temperature had little influence on the optimal aw for aflatoxin production in cowpea meal. However, an increase in temperature resulted in a decreased optimal aw for aflatoxin production on whole cowpeas. When known quantities of aflatoxin were added to cowpea meal which was subsequently steamed for 5 min, only 29% was extractable using a variety of procedures, indicating that the toxin may be bound in some manner to cowpea constituents as a result of heat treatment.