Co-Culture Probiotic Fermentation of Protein-Enriched Cereal Medium (Boza)
Abstract Objective: Boza is a fermented cereal beverage which is produced by co-culture fermentation of lactic acid bacteria and yeasts. In addition to the nutritional properties of cereals used in the production, it is also suitable to be gaining functional properties by fermenting with probiotic microorganisms. Methods: In this study, protein content of probiotic boza was increased by the addition of gluten, zein and chickpea flour and the volatile compounds formed during co-culture fermentation of the cereal medium with Lactobacillus acidophilus, Bifidobacterium bifidum and Saccharomyces boulardii were determined. Results: It was determined that chickpea added boza provided the highest cell counts of Lactobacillus acidophilus (7.92 logs CFU/g), Bifidobacterium bifidum (7.32 log CFU/g) and Saccharomyces boulardii (3.26 log CFU/g) during storage. With the addition of gluten, the protein content of the sample was enriched four times more when compared with control boza. During fermentation and storage, a total of 36 different compounds were identified with the major compounds as 9,12-octadecadienoic acid, 9-octadecenoic acid, hexadecanoic acid and hexadecanoic acid, 2-hydroxy-1-(hydroxymethyl)ethyl ester. The concentration of volatile compounds generally decreased during storage of samples. According to Principle Cluster Analysis results, enriched protein samples had similar projections due to their fatty acid contents and the main difference was shown in the control sample. Conclusions: The results of this study indicate that chickpea, single or mixture with cereals, can be a good substrate for probiotic microorganism production for acceptance as probiotic foods.
Growth and survival of a probiotic yeast in dairy products
Abstract Poor survival of probiotic bacteria in yogurt has been recorded. Growth of a probiotic yeast, Saccharomyces boulardii , in association with the bio-yogurt microflora, by incorporating the yeast into commercial bio-yogurt, has been suggested to stimulate the growth of the probiotic organisms and to assure their survival during shelflife. Therefore, the ability of growth and survival of the probiotic yeast itself in diary products, namely bio-yogurt, UHT yogurt and UHT milk were investigated. S. boulardii was incorporated into the dairy products and stored at 4°C over a 4-week period. pH, Lactose utilisation and the production of organic acids were monitored at each interval. Based on the results in this study, the probiotic yeast species, S. boulardii , has the ability to grow in bio-yogurt reaching maximum counts exceeding 10 7 cfu/g. The number of yeast populations was substantially higher in the fruit based yogurt, mainly due to the presence of proportions of sucrose and fructose derived from the fruit. Despite the inability of S. boulardii to utilize lactose, the yeast species utilized available organic acids, galactose and glucose derived from bacterial metabolism of the milk sugar lactose present in the dairy products. Excessive gas and alcohol production by the yeast species proved, however, to be major constraints for incorporating this yeast into bio-yogurt.
Fermentation technologies for the production of probiotics with high viability and functionality.
There is growing scientific evidence supported by mechanistic and clinical studies that probiotics can provide health benefits. As probiotics are highly sensitive to many environmental factors, and because the propagation of many strains of intestinal origin is not straightforward, most commercial strains are selected on the basis of their technological properties - ruling out some strains with promising health properties. To date, probiotic production has almost exclusively been carried out using conventional batch fermentation and suspended cultures, in some cases combined with the use of sublethal stresses to enhance cell viability, the addition of protectants or microencapsulation to provide cell protection. However, other less conventional fermentation technologies, such as continuous culture and immobilized cell systems, could have potential for enhancing the performance of these fastidious organisms. These technologies might be employed to develop strains with improved physiology and functionality in the gut and to enlarge the range of commercially available probiotics, as well as expanding product applications.