Biofortification of riboflavin and folate in idli batter, based on fermented cereal and pulse, by Lactococcus lactis N8 and Saccharomyces boulardii SAA655

AIMS

Lactococcus lactis N8 and Saccharomyces boulardii SAA655 were investigated for their ability to synthesize B-vitamins (riboflavin and folate) and their functional role as microbial starters in idli fermentation.

METHODS AND RESULTS

In this study, ultra-high performance liquid chromatography and microbiological assay were used to determine the total riboflavin and folate content respectively. Increased levels of folate were evident in both L. lactis N8 and S. boulardii SAA655 cultivated medium. Enhanced riboflavin levels were found only in S. boulardii SAA655 grown medium, whereas decreased riboflavin level was found in L. lactis N8 cultivated medium. To evaluate the functional role of microbial starter strains, L. lactis N8 and S. boulardii SAA655 were incorporated individually and in combination into idli batter, composed of wet grounded rice and black gram. For the experiments, naturally fermented idli batter was considered as control. The results indicated that natural idli fermentation did not enhance the riboflavin level and depleted folate levels by half. In comparison with control, L. lactis N8 and S. boulardii SAA655 incorporated idli batter (individually and in combination) increased riboflavin and folate levels by 40-90%. Apart from compensating the folate loss caused by natural fermentation, S. boulardii SAA655 fermented idli batter individually and in combination with L. lactis N8 also showed the highest leavening character. Moreover, the microbial starter incorporation did not significantly influence the pH of idli batter.

CONCLUSION

Incorporation of L. lactis N8 and S. boulardii SAA655 can evidently enhance the functional and technological characteristics of idli batter.

SIGNIFICANCE AND IMPACT OF THE STUDY

UN General Assembly declared 2016 the International Year of pulses emphasizing the importance of legumes as staple food. Furthermore, this is the first experimental report of in situ biofortifcation of riboflavin and folate using microbes in pulse based fermented staple food. The current study suggests possible avenues for research towards an economical strategy to reduce B-vitamin deficiency among the consuming population.

Bran fermentation as a means to enhance technological properties and bioactivity of rye

Response surface methodology was applied to study the effects of fermentation on the levels of phytochemicals (folates, phenolic compounds, alkylresorcinols) and on the solubilization of pentosans in rye bran from native and peeled grains. Furthermore, the microbial composition of the brans before and after fermentation was studied. Peeling reduced the microbial load and lower microbial counts were detected in the fermentation experiments carried out with the bran from peeled grains. High temperature and long fermentation time favoured the growth of indigenous lactic acid bacteria (LAB), and a diverse microbial community was detected. The brans contained low levels of aerobic spore-forming bacteria, but their number was not increased during the fermentations. Fermentation of both brans increased the levels of folates, easily extractable total phenolics and free ferulic acid. During fermentation of bran from native grains, the levels of alkylresorcinols slightly increased but during fermentation of bran from peeled grains they decreased. Significant increase in soluble pentosans was established in both types of rye bran fermentations. Enhanced bioactivity and solubilization of pentosans with limited microbial growth were obtained after 12-14 h fermentation at 25 degrees C. The results suggest that fermentation is a potential bioprocessing technology for improved technological properties and bioactivity of rye bran.