Efeito protetor de coprodutos do processamento de frutas tropicais em cepas probióticas Lactobacillus após liofilização e armazenamento

Abstract

The production of fruit represents a segment of great importance for the economy, since most of this production is destined to the processing industry for the manufacture of several products, with that, it generates large quantities of co-products agroindustries, these constituted of barks, seeds, bagasse, stalks and other parts of the fruit which contain in their composition simple sugars and non-digestible oligosaccharides, as well as phenolic compounds. It is believed that these co-products can act in the protection of lactic acid bacteria (LAB), such as Lactobacillus, during preservation processes applied in industry, replacing sugars that are generally used, adding value to these coproducts that are commonly discarded in the environment. This study evaluated the protective effect of co-products from the processing of tropical fruits (Malpighia glabra L.), cashew (Anacardium occidentale L.) and guava (Psidium guayaba L.) on probiotic strains (Lactobacillus paracasei L-10, L. casei L-26 and L. acidophilus LA-05) after freeze-drying and storage. For this, analyzes of the viability of Lactobacillus strains were performed before and after the lyophilization process in the presence of the tested fruit co-products. In addition, the occurrence of damage to membrane integrity, membrane potential and efflux activity of Lactobacillus strains caused by the lyophilization process with each fruit co-product was evaluated by means of flow cytometry; as well as analysis of the survival of lyophilized strains during 90 days of storage under refrigeration and ambient temperature. The lyophilization process caused a decrease in viable cell counts of all Lactobacillus strains tested, with the greatest reductions for lyophilized L. casei L-26 in the absence of fruit co-products (approximate reduction of 2.9 log CFU / mL). After 48 h of lyophilization, the number of viable cells was higher for lyophilized strains with fruit co-products (7.4 - 8.9 log CFU / mL) when compared to lyophilized strains without substrate or in the presence of fructoligosaccharide. Flow cytometric analysis demonstrated the protective effect exerted by fruit co-products tested on Lactobacillus strains, which presented lower subpopulations with damage, mainly in membrane integrity and efflux activity. Lactobacillus strains lyophilized with co-products maintained viability (approximately 2.6-5.3 log CFU / mL) after 90 days storage at room temperature or refrigeration, with counts higher than lyophilized strains without co-products (1-4 log UFC / mL). In general, the greatest protective effects were observed for lyophilized strains in the presence of the acerola co-product (~ 5 log CFU / mL). The protective effects exerted by fruit co-products tested on Lactobacillus strains could be related to the high amounts of sugars, fibers and phenolic compounds present in these materials. These results show the potential of the coproducts of the processing of acerola, cashew and guava as protective substrates for use in the process of lyophilization of probiotic strains of Lactobacillus.