Establishing processing conditions for canning cowpea seeds in tomato sauce

Abstract

The thermal process time and sensory attributes of Ife‐BPC cowpeas canned in tomato sauce were studied. Heat resistance of Bacillus stearothermophilus 1518 was determined by the plate count method at 114.5 and 120.6°C. Surviving spores were cultured and TDT curves were plotted from these data to obtain D values of 2.2 ± 0.2 min at 120.6°C and 7.5 ± 0.5 min at 114.5°C. Heat penetration studies were conducted on two can sizes and at two operating temperatures. Thermal process parameters were determined using both the general and formula methods. There was no significant difference (P < 0.05) in the process times determined by the two methods although slightly higher values were obtained with the formula method. The medium can size required a longer process time to approach the retort temperature than the small can size. The lethal effect of sterilizing at 120.6°C resulted in a lower D‐value, higher sterilizing value (F0), and higher safety ratio (a/b) than at 114.5°C. The final F0 at the end of processing was greater than the targeted F0 (11.0 min) from the 5D value, suggesting that the processing time is adequate for safe food production. Taste panel assessments were conducted to identify optimal processing conditions. The sensory attributes of dry and semi‐dry Ife‐BPC cowpeas canned in tomato sauce were compared with those of imported baked beans. Semi‐dry processed cowpeas had high consumer preference over the dry seeds, and acceptable canning qualities similar to those of the imported baked beans.