Papers for

Papers for

Microbiological Screening of a Starter Culture of Probiotic Status from Formulated Non-Dairy Yoghurt Analogue from Natural Fermentation of Soymilk-Achamilk Blends

Non-dairy probiotic yoghurt analogue was formulated using cream variety of soybean (Glycine max L.) and white variety of acha (Digitaria exilis). One kilogram of cleaned soybean and 500grams of cleaned acha were used to produce soymilk and acha milk. Soymilk and acha milk were blended in different ratios (100:0; 90:10; 80:20: 70:30; 60:40; 50:50; 0:100), respectively. The various blends were pasteurized at 800C for 30 minutes, cooled to 44±20C fermented naturally for 8 hours until desired degree of acidity was achieved, cooled rapidly to 8±20C, packaged in sealed plastic bottles and stored in the refrigerator. Microbiological analyses were done on the isolates obtained from incubation in an anaerobic jar at 370C for 48hours. The isolates were stored in sterile agar slants after purification by successive streaking on MRS and ST agar before being subjected to characterization. Microbiological screening (morphological, physiological and biochemical tests) was done to identify characterized a working isolate of probiotic status. Further assessment of performance of probiotic strains {acidifying activity and exopolysaccharide (EPS) production} were performed. Results show that the isolates were Gram positive, catalase negative, oxidase negative and non-sporing. A total of 7 isolates produced lactic acid. Among the 5 rods,3 were able to grow at 450C ,produced acid and gas from glucose (characteristic of Lactobacillus spp.);2 isolates grew between 15 and 370C,at 4%NaCl and pH of 9.6 (characteristic of Streptococcus spp) while  2 isolates grew between 15 and 420C, produced acid from glucose and  lactose, citrate positive (characteristic of Lactococcus spp). All the isolates showed tolerance to 5% bile and 3.0% NaCl (inhibitory substances) .There was no significant difference (p>0.05) in the acidifying activities of Lactobacillus, Lactococcus and  Streptococcus species. After 6 hours of incubation, an increase in pH from 4.78 to 5.87(for Lactobacillus spp), 4.12 to 5.86(for Lactocccus spp) and 4.20 to 5.60(for Streptococcus spp) were observed. Lactococcus spp showed an acid value of 0.29g100m-1lactic acid after 6 hours and increased from 0.40 to 0.75g 100ml-1 after 12 and 24 hours respectively. These isolates were used for the formulation of probiotic yoghurt analogue.
 

Mbaeyi, I. E., Ogbonna, J. C. and Onwuka, N. D. , Department of Microbiology, University of Nigeria, Nsukka, Enugu State, Nigeria. Department of Food Science and Technology, University of Nigeria, Nsukka, Enugu State, Nigeria

Download |   View Abstract