Banca de DEFESA: VANESSA MORAES RAMALHO CASTRO

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
DISCENTE : VANESSA MORAES RAMALHO CASTRO
DATA : 19/07/2018
HORA: 09:30
LOCAL: UNIVERSIDADE FEDERAL RURAL DO RIO DE JANEIRO
TÍTULO:

Tolerance of Lactobacillus to Oxidative Stress in the Presence of Milk or Honey

PALAVRAS-CHAVES:

probiotics, honey and milk, oxidative stress

PÁGINAS: 61
GRANDE ÁREA: Ciências Agrárias
ÁREA: Ciência e Tecnologia de Alimentos
RESUMO:

Prebiotics are substances that beneficially affect the host by selectively stimulating the growth and / or activity of one or a limited number of bacteria in the colon; the probiotic bacteria. Findings of previous research have shown that honey and milk are matrices that aid in the viability of probiotics during storage, as well as improve their metabolism. Lactobacilli are benefited in environments with low redox potential and the presence of antioxidant compounds is important in this context. Milk and honey food matrices are rich in antioxidant substances, but the role of these antioxidants on prebiotic activity has not been determined.. Thus, the objective of the present study was to study the tolerance of lactobacilli to the oxidative stress induced by hydrogen peroxide in the presence of milk and honey. For this purpose, cell viability assays were performed with and without the addition of hydrogen peroxide (H2O2), in three different matrices: saline solution, 5% honey solution or 12% reconstituted skim milk. To evaluate the oxidative stress caused by exposure of lactobacilli to hydrogen peroxide, lipid peroxidation assays were performed in different probiotics (L. paracasei, L. rhamnosus, L. acidophilus and S. bourlardii). The milk matrix provided protection for the strains L. paracasei and L. rhamnosus, whose viability was equivalent to that of the non-stressed culture. This milk protective effect was not observed in the survival of the L. acidophillus strain which was the same independent of the matrix. Exposure to peroxide did not affect the viability of yeast S. bourlardii. Five percent honey solution did not maintain the viability of probiotic microorganisms exposed to hydrogen peroxide and, on the contrary, caused a significant reduction in viability of the strain of L. rhamnosus (P <0.001). Lower lipid peroxidation due to peroxide exposure, expressed as malonaldehyde, was observed with the microorganisms L. acidophilus and L. rhamnosus, but this marker showed no relation to viability. Although they are all H2O2 producers when cultured in honey solution, it is assumed that probiotic bacteria have different mechanisms to avoid the toxic effects of the reactive radicals caused by exogenously added H2O2. Key words:

MEMBROS DA BANCA:
Externo à Instituição - JANINE PASSOS LIMA DA SILVA - EMBRAPA
Externo ao Programa - 2230482 - JULIA HAUCK TIBURSKI
Presidente - 359403 - ROSA HELENA LUCHESE