Abstract: The quality changes of immature (green fruit) and mature noni fruit (yellow fruit) during natural fermentation (the fermented fruit product is called Jiaosu in Chinese) were studied in term of superoxide dismutase (SOD) activity, tyrosinase inhibitory activity, pancreatic lipase inhibitory activity, and the contents of total sugar and total polyphenol. The results showed that pH value, total number of colonies, yeast and mold counts in fermented immature noni fruit were higher than those in fermented mature yellow fruit, whereas the contents of soluble solids, total sugar, reducing sugar and total polyphenol were lower. During the late stage of fermentation, the inhibition rate of tyrosinase in immature fruit was higher than that in mature fruit. During the entire fermentation process, the inhibition rate of pancreatic lipase in immature noni fruit remained at a high level greater than 85%. The inhibition rate of pancreatic lipase in mature fruit increased with the prolongation of fermentation time, indicating that noni fruit Jiaosu has the potential in skin whitening and preventing obesity.

Key words: noni fruit; maturity; Jiaosu; tyrosinase inhibition rate; pancreatic lipase inhibition rate