Prebiotic Potential of Resistant Starches and Dietary Fibers of Sri Lankan Traditional Rice Varieties and its Application in the Food Industry

This study was conducted to investigate the prebiotic potential of selected traditional rice varieties by inoculating with probiotic bacterium Lactobacillus plantarum. Five traditional rice varieties; Suwandel, Pachchaperumal, Kaluheenati, Kuruluthuda and Madathawalu as treatments and BG-358 as control, were used in flour form. Dietary fiber (DF) and resistant starch (RS) content of selected varieties were measured according to AOAC method 2009.01, 2011.25 and 2002.02. Modified culture media was prepared by combining MRS agar with rice flour in 4:1 ratio and L.plantarum was inoculated while inhibiting other bacterial growth using ciprofloxacin. Colony forming units (CFU) and prebiotic activity score (PAS) was calculated by inoculating L. plantarum as the probiotic and Escherichia coli was used as enteric bacteria. Rice idli mix was developed by using two rice varieties with highest PAS value and the best product was determined by a sensory evaluation with twenty five semi-trained panelists. According to the results of DF, RS, CFU and PAS evaluation, all traditional varieties were significantly higher (p<0.05) compared to control variety. Kaluheenati possesses significantly (p<0.05) the highest value of 6.97±0.03% and 2.53 ± 0.02% for DF and RS respectively. CFU were varied from 1.87 ± 0.04x10⁷ to 2.58 ± 0.05 x10⁷ and highest CFUs were reported in Kaluheenati. PAS was varied from 1.23 ± 0.01 to 1.46±0.02 and Kaluheenati was reported significantly higher (p<0.05) score compared to other traditional varieties. Best idli mix was combination of kaluheenati and suwandel in 1:1 ratio. The results revealed that kaluheenati has the highest DF, RS and higher PAS reflects traditional varieties have higher prebiotic potential.