Production of probiotic boza and determination of some properties

In this study, it is aimed to research the possibility of using boza, cereal fermented beverage, as a probiotic product. On this purpose, some microbiological, physical, chemical and sensory properties of boza produced using certified probiotic microorganisms (S. boulardii, L. acidophilus LH-5 ve B. bifidum BF-2) as starter culture and control boza in fermentation and storage time were determined. The 5 boza samples were 4 probiotic boza (A, B, C, D) which prepared with using bacteria 1.5x104, 2x104, 2.5x104 and 3x104 times of 2x102 yeast and a control (K) boza prepared with using 5% commercial boza as culture. Sampling of boza were done in 5 different time (0., 6., 12., 18. and 24. hour) of fermentation and 6 different day (0., 3., 6., 9., 12. and 15. day) of storage. S. boulardii and total yeast, total lactic acid bacteria (LAB; L. delbrueckii ssp. bulgaricus ve L. acidophilus), B. bifidum, dry matter, total titrable acidity, pH, water activity, sucrose, maltose, glucose, fructose, lactic, malic and citric acid, color, viscosity, syneresis and sensory analyses were analyzed of boza during fermentation and storage time. It is determined that, after fermentation S. boulardii, LAB and B. bifidum content of boza samples significantly (p<0.01) increased 1.78, 0.48 and 0.16 logarithmic unit fold from initial levels of 2, 6 and 6 log10 cfu/mL, respectively. In addition the total titrable acidity value significantly (p<0.01) increased from 0.20% to 0.67% and pH value significantly (p<0.01) decreased from 6.41 to 5.37, however dry matter, averagely 26.54% and water activity averagely 0.95 values did not change significantly (p>0.05) during fermentation. It is also determined that sucrose and citric acid content of boza sample decreased significantly (p<0.01) 52.09 g/L and 0.16 g/L, respectively while glucose, fructose and lactic acid content significantly increased (p<0.01) 14.87 g/L, 23.26 g/L and 3.35 g/L during fermentation and maltose content did not change significantly (p>0.05). During fermentation according to different production method; it is determined that the microorganism content of A, B, C and D samples increased significantly (p<0.01) and the maximum S. boulardii, LAB and B. bifidum content was determined in D sample as 3.56, 6.93 and 6.82 log10 cfu/mL, recpectively. In order of A, B, C, D samples total titrable acidity content was significantly (p<0.01) increased 0.06% and pH value significantly (p<0.01) decreased 0.12 units. Also it is determined that sucrose content of A, B, C and D boza samples significantly (p<0.01) decreased from 157.15 to 103.01 g/L, maltose content from 3.77 to 0.91 g/L, citric acid content from 0.69 to 0.50 g/L, glucose content from 9.37 to 6.07 g/L, fructose content from 11.18 to 8.84 g/L and lactic acid content significantly (p<0.01) increased from 1.85 to 2.97 g/L during fermentation.It is determined that although little increasing at the beginning S. boulardii content of boza samples did not change while LAB and B. bifidum content decreased 0.90 and 1.33 log10 cfu/mL units respectively, dry matter content decreased from 26.27% to 24.73%, pH value decreased from 5.37 to 4.47, total titrable acid content increased from %0.67 to %1.10 significantly (p<0.01) and color, viscosity and water activity did not change significantly (p<0.05) during storage. Also sucrose, maltose and citric acid content of boza samples significantly (p<0.01) decreased 93 g/L, 0.90 g/L and 0.32 g/L, respectively and glucose, fructose and lactic acid content significantly (p<0.01) increased 92.62 g/L, 48.62 g/L and 3.18 g/L during storage, respectively During storage according to different production method; S. boulardii content of A, B, C and D samples found to be similar, sample D had the maximum LAB, B. bifidum and titrable acidity content and pH value of all boza samples were under 5.10 and colour values of samples were identical. In addition sample D had the minimum sucrose, fructose, citric acid and the maximum lactic acid content and sample K had the minimum glucose content. Also it is determined that syneresis value of K, A and D was 0.64%, 4.04% and 11.37% respectively. While different production and storage method did not affect sensorial color and consistency properties, it affected mouth feel, acidity taste, odor and general like. The probiotic boza samples (A, B, C ve D) and control sample (K) got 3 or more point according to 1-5 hedonic scale for sensorial evoluation. It is determined that the probiotic boza samples had contained 104 and 106 cfu/mL yeast and bacteria and these values were protected for 15 day storage, is a safe food with low pH value, suitable for TS 9778 Boza Standards with dry matter and titrable acidity values, acceptable as sensory and get points as equal or more compare with control. As a conclusion it is possible to produce boza, a traditional Turkish product, as probiotic product with using certified probiotic microorganism and make contribution to public health.