Study On Solid-State Fermentation Of Whole Oats By Probiotics

Compared with conventional fermented dairy foods, cereal-based food products offer some benefits including high dietary fiber, low fat and cholesterol. For this reason, non-dairy probiotic fermented food has become an important trend in the development of probiotic foods. Oat cereal is one of full nutritional value of food. Therefore, for the development of grain fermented food with prebiotic effect, conditions of the whole oats solid-state fermentation by lactic acid bacteria were optimized, and the fermentation properties and dry conditions to oats solid-state fermentation products were studied.In this study, solid-state fermentation with whole oats powder as the only medium by Lactobacillus plantarum TK9, Lactobacillus casei Zhang or Bifidobacterium lactis V9was performed. In order to obtain the high viable counts of the three stains, the optimal fermentation condition were obtained by single-factor and orthogonal experiments of the moisture content, inoculum size, fermentation time and the initial pH of medium. In the optimal conditions (moisture content55%, inoculum size8%, pH6, fermentation28h and under37℃), the highest populations of L. plantarum TK9were2.85×109CFU/g. L. casei Zhang showed the highest viable counts of6.32x10CFU/g in the optimal conditions (moisture content55%, inoculum size9%, pH6, fermentation36h and under37℃). When the fermentation conditions were moisture content65%, inoculum size10%, pH6.5, anaerobic fermentation time40h and under37℃, the highest viable cells of B. lactis V9were3.17×108CFU/g.By analyzing the production and the nutrition compositions of oats before and after fermentation, the following conclusions could be made. For the three strains, the contents of soluble dietary fiber all had no significant change (P>0.05). For L. plantarum TK9and L. casei Zhang, almost no change was seen in the β-glucan content, while no significant decline for B. lactis V9(P>0.05). Therefore, oats solid-state fermentation products by three kinds of lactic acid bacteria still have prebiotic efficacy of β-glucan. After fermentation by the three strains, the amount of free amino acids increased by38.11%,52.97%and27.22%, respectively. And the content of peptide, whose relative molecular weight is less than6000Da, increased by4.44%,10.62%and5.96%, respectively. In addition, the titratable acidity was10.01mL,9.93mL and8.40mL, respectively. And the amount of lactic acid was506.67mg/100g,446.67mg/100g and383.33mg/100g, respectively.The study of dry conditions to oats solid-state fermentation products was performed under the condition of ordinary drying, vacuum drying and freeze-drying. The results revealed that the survival of viable cells in oats fermented products after solid-state fermentation by the three strains can reach the basic standards of probiotic products. Compared with ordinary drying and vacuum drying, the protection effect of freeze-drying was the best. And the highest survival rates in oats solid-state fermentation products, which were added by10%galactooligosaccharides as protectant, were22.81%,31.65%and17.67%, respectively.