Some microorganisms including bacteria, yeasts, moulds and even algae are

associated with fermented foods, forming a complex ecosystem. Among these

organisms, lactic acid bacteria (LAB) are responsible for most of the physicochemical and aromatic transformations that are intrinsic to the fermentation process. LAB were first isolated from milk and have since been found in foods and fermented products such as meat, milk products, vegetables, beverages and bakery products (O’Sullivan et al, 2002).

Following the household method of fermentation used in making the Ethiopian

bread injera, fermentation of a flour/water slurry was carried out. The fermentation experiments were done at temperatures of 25 and 35 °C with whole grain wheat flour, whole grain tef (Eragrostis tef) flour and commercial bakery flour of 70% extraction rate. The slurry was made by mixing 300 g flour and 600 ml water. Backslopping was done by adding a portion of the slurry which was fermented in a previous batch as a starter (0.1%, 1.0%, and 10%) to the next batch to be fermented. During the fermentation, samples were taken at definite intervals of 3, 6, 9, 12, 18, 24, 48 and 84 hours respectively and kept frozen until they were used for analysis. The pH and titratable acidity were recorded and the organic acids were determined by HPLC using an Aminex® HPX-87H column, The growth of lactic acid bacteria including the typing of species/strains was also determined.

Samples of the fermenting slurry were taken for analysis and the final concentration of lactic acid was found to be approximately 1 g per 100 g. A higher amount of inoculum gave a quicker lowering of pH, and also a lower initial pH. A smaller inoculum amount showed a delayed start in the lowering of pH. A higher temperature increased the production rate of lactic acid.

The current investigation reports the search for a multipurpose composite substrate composed of dairy and cereal components for probiotic organisms. Probiotic Lactobacillus acidophilus NCDC 13 was inoculated in a substrate containing different combinations of whey-skim milk (WSM), germinated pearl millet flour (GPMF) and liquid barley malt extract (LBME). L. acidophilus NCDC 13 grew well in all the substrate combinations, though WSM + LBME was a better substrate than WSM + GPMF. Increasing levels of GPMF and LBME had a positive effect on the fermentation dynamics, acidification rate and the viability of probiotic culture. WSM in combination with 5% GPMF and 3% LBME resulted in the

highest growth rate of the probiotic organism. The growth rate as well as

acidification rate could be enhanced at low generation times by increasing

inoculation levels to 4% and 5% and incubating for 8 and 6 h respectively. As the viable cell counts were above the required standards, 4.0% inoculum levels for 8 h fermentation time was selected as optimum. A base model for probiotic fermented formulations containing dairy and cereal ingredients with quick fermentation,high probiotic counts and a suitable pH range for acceptability of the fermented foods was established during the investigation.

The effect of alginate-chitosan encapsulated Flavourzyme on the water-soluble and water-insoluble peptides and amino acids released during Cheddar cheese ripening was investigated. Increased and prolonged proteolysis was observed in cheeses incorporated with encapsulated Flavourzyme. Rapid proteolysis and increased accumulation of hydrophobic or high molecular weight peptides was however observed in cheeses with free Flavourzyme compared to control (without Flavourzyme) or cheeses with encapsulated Flavourzyme. Concentration of watersoluble peptides increased with the concentration of encapsulated Flavourzyme in the cheese. Most free amino acids were about 3 times greater in cheese with encapsulated Flavourzyme compared to control cheese after 30 days ripening and

about 7 times greater after 90 days ripening. Total amino acid content was highest in cheese with encapsulated Flavourzyme followed by free Flavourzyme treated cheese and lowest in control cheese. Flavourzyme encapsulated in slow release alginate-chitosan matrix can be a potential delivery system for flavour enhancement during cheese ripening.

The effect of fermentation on the production of lactic acid, pH-development an on the growth of Escherichia coli strain NG7C in gruels made of whole grain wheat and whole grain tef under different conditions was studied. The results show that the number of E. coli decreased rapidly in both 1% and 10% back-slopping quicker than in control that was fermented without back-slopping. The growth of E. coli in the gruels was found to depend not only on the amount of lactic acid and pH but also on the amount of undissociated lactic acid both in whole wheat gruel and whole tef gruel. At the lowest pH (3.5) obtained in all fermentation experiments, the number of E. coli was found to be reduced to > 6-log-unit. The initial pH of the slurry was adjusted to different levels by adding lactic acid alone or by adding

hydrochloric acid. It shows that the lower pH have an effect on the growth of

E. coli. However a lower pH caused by the addition of lactic acid is more effective in reducing the number of E. coli than addition of HCl. The sample with the highest amount of undissociated lactic acid had the fastest reduction of viable E. coli during fermentation.

Low-alcoholic beverages, especially those produced from fruits, are increasing in demand and are being consumed in the form of table beverages. Present investigation features development of such new table beverages using the underutilized regional millets- finger millet (ragi) and pearl millet (bajra). Alcoholic fruit beverages (fruits wines) are conventionally prepared from apples, peaches, oranges, blackberries, mangoes etc. In order to accommodate an ever-increasing demand, more wineries are starting to increase their versatility. Review of literature reveals that hardly any work that is documented on the ragi and millet based alcoholic beverages. Thus the present study was focused on utilization of underutilized millets and blending them with selected fruits to develop low alcoholic beverages with appreciable acceptability. Different blends of fruit juices (green grapes, black grapes and apple) with finger millet and pearl millet along with germinated wheat kernels as inducers were taken and fermentation was carried for a period of 8-10 days using brewer’s yeast (Saccharomyces cerevisiae).

Any undesirable microbial contamination was checked by adding potassium metabisulphite (KMS) @ 180 ppm. After completion, ethanol content in fermented product was analyzed and physico-chemical tests namely pH and % Titratable acidity (TA) were performed for all the samples. The microbial quality was also checked in all beverage samples. Such developed novel non alcoholic beverages were found to be acceptable and consumer friendly with appreciable shelf stability.

A total of 203 lactic acid bacteria (LAB) isolated from vegetables and traditional fermented food products of India such as idli batter, dhokla batter and dahi were screened for exopolysaccharide (EPS) production. Based on the amount of EPS produced, 17 LAB isolates were selected for biochemical and genetic characterization using 16S rRNA gene sequencing. The isolates were belonging to the genera Lactobacillus, Weissella and Pediococcus. In vitro examination was performed to evaluate their probiotic potential. Resistance to low pH and 0.3 % bile salts was studied. Bile salt hydrolase (BSH) activity, susceptibility to various antibiotics and antimicrobial activity against the non pathogenic E. coli K12 were also investigated. The results showed that the isolates could not grow in the presence of oxbile however some survived exposure to it for 2.5 h. Some isolates were able to grow in the presence of sodium taurocholate and showed considerable antimicrobial activity against E. coli K12. Five isolates were showing

BSH activity which is reported for the genus Weissella for the first time. The

results suggest that traditional fermented products could be an alternative and

readily available