The influence of pasteurization and starter culture on methanol content and bio-profile of fermented Morinda citrifolia Linn. (Noni) fruit juice

Abstract Morinda citrifolia L., generally known as noni, is commonly used in Thai medicines and cuisine. Several bioactive phytochemicals have been isolated and identified from the noni plant, and their compositions differ based on the cultivars and harvesting period. Different types of fermented noni fruit juices (FNJ) were used as health supplement in several southeastern countries. The formation of a large amount of alcohol, especially methanol, in FNJ is one of the major hindrances to FNJ production. The current study explains the impact of starter culture (Lactobacillus plantarum SK15), pasteurization and addition of EGCG on alcohol content, bioactivity, and the physiochemical property of FNJ. The pH and sugar content of the samples were reduced during fermentation, while the organic acid content increased. The samples with EGCG obviously exhibited high total phenolic content and antioxidant activity. The level of pectin was high, and pectin methylesterase (PME) activity was low in EGCG-added samples compared with other samples. The alcohol content of the samples was under the permissible level of Thai standard; specifically, the methanol level was low in EGCG-added samples. Pasteurization and addition of starter culture did not influence any of the studied parameters. About 70% of acceptability index was observed for FNJ samples in the sensory evaluation. The study concluded that the addition of EGCG effectively reduced the alcohol content and improved the quality of FNJ. Also, further studies are required to reveal the role of starter culture in noni fruit fermentation.