Physicochemical characterization and antibacterial activity of Moringa oleifera Lam leaf powder treated at different temperatures

The changes in phenolic, flavonoid, and tannin (condensed and hydrolyzable) contents were determined in crude mucilage of dried Moringa oleifera leaf powders oven-treated at two different temperatures (80 and 100 °C) for 15 and 30 min. The appropriate temperature with minimum loss of bioactive compounds was also evaluated based on resistance to acid and enzyme digestion and antimicrobial activity against two lactic acid bacteria of the Lactobacillus genus. Treatment temperature and duration significantly (p < 0.05) affected the pH, moisture, titratable acidity, and bioactive compound of the leaf powder. Total phenols, favonoids, tannins (condensed and hydrolyzable), and sugar contents decreased significantly, while pH values increased with increasing time and temperature. Nutrient loss was lowest at 80 °C, thereby providing probiotic benefits compared to those at 100 °C. High-temperature (100 °C) treatments adversely affect the antibacterial activity of Moringa oleifera leaf extracts against both probiotic Lactobacillus bacteria.