Antioxidant Capacity with Physical Property Variations of Morinda citrifolia L. Juice in Traditional Fermentation

Morinda citrifolia L. (noni) has been used widely as traditional folk medicine. Previous studies have shown that the antioxidant capacity of noni juice varied significantly during traditional fermentation. Yet, precise studies are essential to identify the parameters which can affect the fermentation process and ultimately lead to such variations in the antioxidant capacity of noni juice. The aim of the present study was to determine the physical property variations during traditional fermentation of noni juice and then to identify their correlations to antioxidant capacity. Traditional fermentation of noni juice was allowed for two months and the temperature and pH of juice, temperature and humidity within fermenter and juice volume were monitored. Variation of antioxidant capacity was determined by DPPH (2-diphenyl-1-picrylhydrazyl) scavenging method. Both temperatures were within the range of 29.5-33 °C. pH of the juice decreased from 3.98 to 3.23. Humidity increased rapidly from 98.95% to 99.90%. Maximum juice volume was about 1.37 L. Maximum antioxidant capacity was around 84% of DPPH scavenging activity. Physical property variations cannot be correlated significantly to the antioxidant capacity of noni juice. Patterns of physical property changes were different from the variation of antioxidant capacity which was maximum in the second week of fermentation.