Effect of Spontaneous Fermentation on the Chemical Composition of Thermally Treated Jack Beans (Canavalia ensiformis L.)

Abstract

To enhance the nutritional quality of jack beans (Canavalia ensiformis) in an in expensive model, natural fermentation was employed on thermally treated jack beans. Two treatment were employed, boiled (100°C for 2 h), ground pressure-cooked (120°C for 30 min) and raw cotyledon unfermented (control). These were contained in separate gourd containers overlaid with clean banana leaves, covered and wrapped in jute bags. They were left for four days under solid substrate fermentation. Microbiological, chemical and mineral analyses were assessed on the samples. Bacillus licheniformis, Bacillus substilis and Streptococcus thermophillus dominated with 100% each frequency of occurrence among the nine bacteria isolates while Rhizopus nigricans and Aspergillus niger were dominant with 75% each frequency of occurrence among the five fungal isolates. Evaluation of antinutritional contents of fermented samples showed remarkable reductions in the tannin of the boiled fermented (0.10%) and ground pressure cooked fermented (0.07%), phytate and cyanide contents in that order was 893.83, 235.53 mg/100 g; 1.02, 7.07 mg kg-1 contents in comparison with the unfermented sample 0.22 mg/100 g, 1246.33 mg/100 g and 41.63 mg kg-1 (tannin, phytate and cyamide ) contents, respectively. The protein contents of the boiled fermented (28.15%), carbohydrate in ground pressure cooked-fermented was 28.85 and 27.12% in the unfermented. Carbohydrate in that order was 48.35, 45.90 and 42.25% contents. Calcium in the boiled-fermented sample was 420 ppm, 246 ppm in ground pressure cooked-fermented and 105 ppm in the raw unfermented. Iron was 4.0, 16.0 and 9.5 ppm, respectively for boiled-fermented, ground pressure cooked-fermented and raw unfermented. Sodium, in that order was 413.0, 416.5 and 329 ppm. Zinc was 280.3, 119.7 and 166.3 ppm, respectively for boiled-fermented, ground pressure-cooked fermented and raw unfermented, respectively.