DESENVOLVIMENTO DE FERMENTO NATURAL LIOFILIZADO INOCULADO COM Limosilactobacillus fermentum E SEU IMPACTO NA QUALIDADE DE PÃES

Abstract

The use of sourdough in bread making, in comparison to commercial yeast, provides many technological, nutritional and sensory advantages, but the process of spontaneous fermentation is little standardized, complex, long and expensive, so the development of a lyophilized (freeze- dried) sourdough promotes many advantages. The addition of lactic acid bacteria (LAB) as starter cultures for sourdough has been showing positive results from a technological and functional point of view, therefore, the objective of this study was to develop sourdough inoculated or not with Limosilactobacillus fermentum (Lf 139) and assess its impact on bread quality. The two sourdoughs (control - not inoculated; and 139 - inoculated with Lf 139) were elaborated and propagated for ten days, then they were freeze-dried, vacuum packed and stored at 28 ºC. At each storage time, the freeze-dried sourdoughs were collected and reactivated for bread production, and the steps of bread production were carried out under the same conditions for all samples. The sourdoughs were evaluated physicochemically and microbiologically during the propagation, the freeze-dried sourdoughs and the bread were evaluated 0, 30 and 60 days after lyophilization. During the propagation period, the lactic acid bacteria count reached the highest values on the third day for the FN 139 (8,10 log10 UFC/mL) and on the sixth day for the FN C (7,53 log10 UFC/mL), the yeast counts, on the other hand, had big variations, stabilizing only around the tenth day (6 – 7 log10 UFC/mL) for both freeze-dried sourdoughs. The presence of these microorganisms that produce gas and organic compounds it’s essential to give the characteristics of the sourdough. The Control and 139 sourdoughs had the lowest pH values on the third day of propagation. Right after lyophilization there was no significant decrease in BAL and yeast counts in both freeze-dried sourdoughs, however, the number of viable cells of these microorganisms, especially the yeasts, decreased significantly after 30 and 60 days, with FNL 139 having better BAL survival rate than FNL C throughout the storage period. Freeze-dried sourdoughs’ pH were not affected by lyophilization and their water activity was < 0,6 throughout the analysis period, thus being considered microbiologically stable. In all samples of fresh sourdoughs, freeze-dried sourdoughs and breads produced, viable E. coli and Salmonella spp. cells were not identified in all the times analyzed. Breads made with FNL C or FNL 139 had the lowest pH values after 30 days of storage, reflecting the pH of these same freeze-dried sourdoughs. As expected, pH values were higher and TTA were lower for Commercial bread. In general, the hardness of samples made with FNL decreased after 60 days of the freeze-dried sourdoughs. Moisture is directly related to the texture of bread but it is also necessary to consider other parameters, such as acidic conditions, EPS production and starch retrogradation, this one, in turn, is also related to the aging of bread. The addition of Lf 139 does not seem to have influenced the color attributes (L*, a* and b*) evaluated in this study. The results show the positive impact of using freeze-dried sourdough inoculated with Lf 139 in the physicochemical and microbiological characteristics of the produced bread, which suggests a greater standardization of bread and the potential of this type of product for the consumer market.