MOLECULAR CHARACTERISATION OF PREDOMINANT LACTIC ACID BACTERIA IN FERMENTED BREADFRUIT (Artocarpus communis) AND PIGEON PEA (Cajanus cajan) AND QUALITY ATTRIBUTES OF THEIR PRODUCTS

Abstract

Breadfruit and pigeon-pea are high yielding crops. However, breadfruit is highly susceptible to deterioration while pigeon-pea is hard-to-cook. Fermentation improves crop preservation, nutritional value and utilisation. Literature on fermentation of Breadfruit (BF) and Pigeon-pea (PP) is sparse. The study was designed to characterise fermenting organisms and determine physicochemical and sensory properties of fermented breadfruit and pigeon-pea products. Breadfruit (BF) and pigeon-pea (PP) were fermented individually using liquid state fermentation at 28±2 oC and 37±1 oC for 24, 48, 72, 96 and 120 h. Biochemical, DNA extraction, Phylogenetic tree, Alignment and 16S rRNA sequencing of fermenting organisms were characterised by molecular methods. The fermented crops oven-dried and milled into flours. Chemical (proximate, pH, Total Titratable Acidity (TTA), anti-nutrients), functional [Water and Oil Absorption Capacities (WAC and OAC), Bulk Density (BD), Foaming Capacity (FC) and Stability (FS), Gelation Capacity (GC)] and pasting properties of fermented samples were determined using standard methods. Based on preliminary trials, flours were blended at ratios 100:0, 90:10, 80:20, 70:30, 60:40 and 50:50 (BF: PP) and analysed for proximate composition using AOAC method. Breakfast meals and cookies were prepared from the flours using standard procedures. Sensory attributes of the products were determined by panelists. Data were analysed using ANOVA at α0.05. Sugar fermentation and gram staining of the selected isolates showed diverse sugars and improved acidity as fermentation proceeded. Sequences of purified DNA products were significantly similar to GeneBank samples. Phylogenetic tree indicated high homology among the identified lactic acid bacteria with change in fermentation duration up to 120 h, reflecting taxonomical relationships among identified species. Alignment established similarity level through the nucleotide numbers across the region. High sequence homology of Lactobacillus plantarum and fermentum with sequence codes of CP011536.1 and CP015308.1, respectively as the dominant lactic acid bacteria were identified. Fermented BF flour contained 4.2-3.6% protein, 8.1-9.3% moisture (dry basis), 2.7-3.0% ash, 3.5-3.0% fibre. The protein, moisture, ash and fibre contents of PP were 24.8-4.5, 8.8-9.2, 3.7-4.0 and 1.4-1.8%, respectively. The pH of BF flour decreased with increased TTA and the same trend was observed in PP samples. The phytate, tannin, cyanide and alkaloid contents of BF and PP were 0.5-0.2 mg/g, 6.2-4.7 mg/g, 1.0-0.1 mg/100g and 1.2-0.2%, and 0.5-0.1 mg/g, 0.9- 0.1 mg/g, 1.2- 0.1 mg/g and 0.9-0.5%, respectively. Breadfruit WAC (346.1-224.8%) decreased while OAC (256.7-286.4%) increased as fermentation progressed. Loose bulk and packed densities were 0.4-0.5 and 0.4-0.6 g/mL, respectively. Decrease in FS and increase in GC values were observed as fermentation progressed at 28±2 and 37±1 oC, respectively. The WAC, OAC, BD, GC of PP increased with decrease in FC and FS. Fermentation improved pasting properties of BF. Meals and cookies prepared with 10-20% PP had significantly higher acceptability levels of 7.7 to 6.4 and 5.8 to 5.0, respectively. Molecular characterisation established genetic variations in Lactobacillus plantarum and fermentum. Fermentation improved the sensory attributes of breadfruit and pigeon-pea flours. Production of breakfast meal and cookies from fermented breadfruit and pigeon-pea flours are recommended.