Prebiotic potential of the finger millet variety, “Oshadha” on Lactobacillus acidophilus (LA 5)

Abstract

In Sri Lanka, finger millet [Eleusine coracana (L.Gaertn)] is the third most important cereal cultivated next to rice, corn and rich in carbohydrates, protein, dietary fiber, minerals including other phyto-nutrients. Probiotics are the “live microorganisms which when administered in adequate amounts confer health benefits to the host” which are generally regarded as safe (GRAS). According to the ISO 29981:2010, a probiotic functional food should contain 108cfu/ml or g of the viable organisms at the time of expiry. Plant based probiotic food products could be better alternatives for many reasons. The present study evaluated the prebiotic potential of finger millet “Oshadha” variety towards LA 5 in terms of viable cell count and selected physico-chemical and nutritional properties. The “Oshadha” variety, harvested when 80 % of the ears become brown in color during “Maha” season was selected considering high nutrients and dietary fiber fractions that favor the survival of probiotics. Grains were sorted, washed, dried, milled, sieved through 0.5mm sieve and slurry was prepared by suspending in water at 1:11 (w/v) ratio and sterilizing. The slurry was inoculated with freeze-dried LA 5 culture in 2% (w/w) and incubated at 44 ºC for 10 h. Microbiological, physico-chemical and compositional parameters of fermented, unfermented slurries were evaluated according to the standard protocols and were statistically compared. In fermented slurry, viable cell count, pH, acidity and viscosity were 8.65±0.14 log10cfu/g, 4.35±0.01, 0.18±0.00% and 2418.43±2.80cP respectively whereas in unfermented slurry, pH, acidity and viscosity were 6.47±0.01, 0.04±0.01 and 583.30±2.74cP respectively. The physico-chemical parameters in fermented slurry were significantly varied (p<0.05) compared to the unfermented slurry. Among protein, carbohydrate, fat and ash, only ash content (2.56±0.36%) of the fermented slurry was significantly high compared to unfermented slurry (1.66±0.39%). In the fermentation, LA 5 utilizes the carbohydrate, produces lactic acid resulting reduction of pH and excretes exopolysaccharides (EPS) which increases the viscosity of the slurry. In conclusion, the “Oshadha” variety could be considered as a potential carrier for LA 5 with prebiotic potential. In Sri Lanka, this is the first study to report that the finger millet (Oshadha variety) is a potential LA 5 carrier with prebiotic characteristics.