Antioxidant properties of probiotic fermented milk supplemented with chestnut flour (Castanea sativa Mill)

Abstract

The effect of sweet chestnut (Castanea sativa Mill) flour in stimulating the growth of probiotic bacteria in fermented skim milk produced with different probiotic strains, namely Lactobacillus acidophilus, L. rhamnosus and Bifidobacterium animalis subsp. lactis was evaluated. Microbial counts, pH, total titratable acidity (LA %) and syneresis were measured in fermented skim milk samples. Additionally, the antioxidant capacities of the samples were measured by Trolox equivalent antioxidant capacity (TEAC), free radical scavenging activity (DPPH), and Ferric Reducing-antioxidant Power (FRAP) assays. The viability and growth proportion index (GPI) of L. rhamnosus were significantly higher than those of L. acidophilus and B. lactis in all samples during storage. Results indicated that all probiotic fermented milks enriched with chestnut flour displayed significant probiotic viability (>7 log10 cfu/g) with high antioxidant capacities. L. acidophilus, L. rhamnosus and B. lactis survived throughout the shelf life of the chestnut-fermented skim milk, and remain at this satisfactory viability level even after 21 days of storage. The antioxidant capacity and phenolic contents were dependent on probiotic strains used. Practical applications Nowadays the focus is rather on the effects of foods on maintenance of health, well-being and prevention of certain diseases than simply satisfaction of appetite or nutrition. The consumers’ health consciousness due to the scientific knowledge of the interactions between diet and health is a driving factor to develop products with health-related claims such as probiotic foods. This paper investigated the effects of chestnut flour supplementation not only on viability of probiotic bacteria but also the antioxidant capacity and phenolic contents in fermented milk throughout predicted shelf life. The results indicated that chestnut flour could be used as prebiotic for further researches to develop dairy products to deliver probiotics.