Antioxidant and antimicrobial properties of yogurt incorporated with Mango (Mangifera indica L.) leaves and their effects on the viability of Lactic acid bacteria (LAB) during storage

Mango (Mangifera indica) is an alternative herbal medicine that has been used for decades. Different parts of mango tree have been applied in enthno medicinal but rarely used in food products. This study mainly focus on antioxidant and antimicrobial properties of yogurt incorporated with mango leaf extract (MLE) and their effect on the microbial count and viability of lactic acid bacteria. The antioxidant properties of MLE and yogurt incorporated with the extract was carried out by analyzing the total phenolic content (TPC) and 1,1- diphenyl-2-picrylhdrazyl (DPPH). The acidity content of yogurt was determined using pH and titratable acidity (TA). The antimicrobial test of MLE was determined using minimum inhibition concentration (MIC) and microbial count was calculated using total plate count. Result showed that 30% of the mango leaves extract has the highest value in DPPH and TPC compared to 20% and 25% extract. The inhibitory properties against selective pathogens were also exhibited. The incorporation of MLE into yogurt retained the antioxidant properties in the product (p < 0.05). The growth of bacteria, yeast and mold were not affected by the incorporation of MLE. There was also no reduction of lactic acid bacteria in all treatments indicating the lactic acid bacteria were viable until the end of storage. The treated yogurt also showed higher acidity (p < 0.05) during storage time. In conclusion, the incorporation of mango leaf extract into yogurt significantly increased the antioxidant properties and tend to increase the stability of lactic acid bacteria to the recommended concentration (6 log(10) CFU/g) in the product.