Development of alginate-pectin microparticles with dairy whey using vibration technology: Effects of matrix composition on the protection of Lactobacillus spp. from adverse conditions.

In this study, lactic acid bacteria with probiotic potential, including Lactobacillus plantarum ATCC8014, L. paracasei ML33 and L. pentosus ML82, were encapsulated with whey-alginate-pectin (WAP) or whey permeate-alginate-pectin (PAP) by an extrusion process using vibrational technology, with the resulting microparticles assessed for their resistance to adverse conditions. The aim was to assess the effect of the encapsulation wall materials on the viability of microorganisms, the encapsulation, refrigerated storage and simulated gastrointestinal tract conditions, the kinetic parameters of acidification, and the morphology of microparticles. The bacteria encapsulated with the WAP wall material were adequately protected. Furthermore, after three months of storage at 4 °C, the encapsulated bacteria exhibited a cell viability of >6 log CFU mL-1. In addition, the encapsulated L. plantarum ATCC8014 and L. pentosus ML82 isolates exhibited the highest viability at the end of the storage period among the assayed isolates. Encapsulated bacteria showed greater resistance to acidic conditions than unencapsulated bacteria when exposed to simulated gastrointestinal tract conditions. The maximum rate of milk acidification by encapsulated Lactobacillus spp. was approximately three-fold lower than that observed for unencapsulated bacteria. The resulting size of the microparticles generated using both combinations of wall materials used was approximately 150 µm. The cheese whey and whey permeate combined with alginate and pectin to adequately encapsulate and protect Lactobacillus spp. from the adverse conditions of the simulated gastrointestinal tract and from refrigeration storage temperatures. Furthermore, the sizes of the obtained microparticles indicated that the encapsulated materials are suitable for being incorporated into foods without changing their sensory properties.

Anti-Escherichia coli effect of Hibiscus sabdariffa L. in a meat model

Abstract Hibiscus sabdariffa L. is used in traditional medicine because of its bioactive properties, such as antioxidant and antibacterial. Escherichia coli is a Gram-negative bacteria and as an indicator of contamination in food. The aim of this work was to evaluate the anti-Escherichia coli effect and the change in pH on the control of aerobic mesophilic microorganisms, using hydroethanolic extract of H. sabdariffa L. in different concentrations in a meat model, verifying its potential as food additive for microbiological stability on ground beef during cooling storage. For the preparation of the treatments, the meat experimental units were elaborated with different concentrations of the vegetal extract (5, 10, 15 and 20%), ground beef and contaminated with E. coli. For pH evaluation, the meat experimental units were added different percentages of hydroethanolic extract. The H. sabdariffa L. antibacterial action reduced two logarithmic levels in practically all treatments. The best pH result was obtained in the meat containing 30% of the extract. The hydroethanolic extracts of Hibiscus sabdariffa L. showed anti-Escherichia coli activity in the presence of refrigerated ground beef. Analyzing the pH results and the count of aerobic mesophilic bacteria, it is possible this extract to be used as a natural food additive.

Avaliação do extrato alcoólico de hibisco (Hibiscus sabdariffa L. )como fator de proteção antibacteriana e antioxidante / Evaluation of the alcoholic extract of hibiscus (Hibiscus sabdariffa L. ) as a protective antibacterial and antioxidant component

O hibisco (Hibiscus sabdariffa L.) possui propriedades antioxidantes e antimicrobianas, e pode ser utilizado como planta medicinal e alimento funcional. Este estudo determinou a intensidade de atividade de inibição (IINIB) e a inativação bacteriana (IINAB) in vitro de dois extratos alcoólicos, obtidos de cálices e frutos com sementes de diferentes acessos de hibisco. As análises foram efetuadas sobre as bactérias de padrão internacional, Enterococcus faecalis, E. coli, Salmonella Enteritidis e S. aureus, associando-se os resultados aos polifenóis totais e antocianinas. Diferenças significativas na atividade antimicrobiana dos extratos alcoólicos foram observadas em ambos os acessos. Salmonella Enteritidis (11,5) e E. coli (12) foram as bactérias mais sensíveis, respectivamente, aos extratos alcoólicos de cálices de hibisco e dos frutos com sementes. S. aureus (5,2 e 0,1) foi a mais resistente a ambos os extratos. Os valores de IINIB foram predominantemente maiores quando comparados aos de IINAB, o que indica que geralmente a atividade bacteriostática é maior do que a bactericida. Os valores de polifenóis totais e de antocianinas do extrato alcoólico de cálices apresentaram diferença significativa e foram superiores aos do extrato alcoólico dos frutos com sementes. Possivelmente exista associação direta entre a concentração de antocianina e a atividade antibacteriana em diferentes estruturas vegetais do hibisco.