Development Of Oat Malt Based Probiotic Beverage

Cereals are one of the most suitable substrates for the development of foods containing probiotic microorganisms since the rapid development of non-dairy probiotic foods. Oat(Avena sativa) is a good source of protein, essential amino-acids, minerals, vitamins, dietary fibre. In addition, beta-glucan is known as prebiotic, stimulating the growth of some probiotic microorganisms. Germination has been claimed to improve the nutritional properties of oats for the purpose of the increase of fermentable sugars.In this paper, oat mixed with malt substrate was fermented with mixed lactic acid bacteria(Lactobacillus acidophilus and Lactobacillus plantarum) to obtain a functional product combining the health benefits of probiotic microorganisms with the oat prebiotic beta-glucan. The fermentation substrate ingredient was studied by response surface methodology. Then process parameters of oat malt probiotic beverage was optimized with L9(34) orthogonal experiment. More over, we studied the stability and shelf life analysis of the fermented product. The main conclusions of this study were as follows:(1) Response surface methodolog was adopted to optimize the fermentation substrate ingredients. The results showed that the optimized factors were 10% mixed cereal flour concentration(ratio of oat malt flour and oat flour 2:1) with 1% skim milk powder concentration. Furthermore,the factors with the influence on the viable cell count and beta-glucan content follows the sequence: ratio of oat malt flour and oat flour, oat malt-oat flour concentration, skim milk powder concentration. Under the optimal condition,the viable cell count and beta-glucan content was 8.75 Log CFU/mL and 564.81 mg/L,which were basically correspond to model prediction.(2) The optimized fermentation process conditions were 4% starter culture concentration, incubation time of 9 h, ratio of L. plantarum and L.acidophilus 1:2 with the results of consumer acceptance. The factors with the influence on the viable cell count follows the sequence: starter culture concentration, ratio of L. plantarum and L.acidophilus, incubation time. While the influence on the titratable acidity was incubation time, starter culture concentration, ratio of L. plantarum and L.acidophilus. Under the optimal condition,the pH level, viable cell count, titratable acidity and free amino nitrogen content of oat malt based probiotic beverage was 3.67, 8.80 Log CFU/mL, 37.42 mL/100 mL and 192.15 mg/L, which were proved to be good taste and flavor.(3) The stability of beverage was studied with mixed stabilizer(pectin, xanthan gum and PGA), the proper addition of them was 0.15%, 0.06%, 0.02%. Under this condition, the minimum centrifugal percent of oat malt based probiotic beverage was 0.851%.(4) The oat malt based probiotic beverage was found to be stable for 21 days with a reduction of 0.33 Log CFU/ml. The content of beta-glucan remained unchanged during the storage. A reduction in the pH level and increase in titratable acidity was proved to be acceptable. At the same time, there was a slight reduction in the free amino nitrogen content and reducing sugar content over the storage period.