Effects of bagging and storage temperature on anthocyanin content and phenylalanine ammonialyase (PAL) activity in mangosteen (Garcinia mangostana L.) fruit pericarp during maturation

The purpose of this research is to investigate the effect of bagging and storage temperature on anthocyanin content and phenylalanine ammonia-lyase (PAL) activity of mangosteen fruit pericarp. Six maturity stages (stage 1 to stage 6, defined by the extension of red or purple colouration on the pericarp) of attached mangosteen fruits with bagged and unbagging were compared. It was found that sunlight had no significant effect on both anthocyanin content and PAL activity. The effect of storage temperature onanthocyanin content and PAL activity were also studied. Fruits at stage 1 (indicated by scattered of pink spot on pericarp) were harvested and allowed to develop red colour to stage 6 at different storage temperatures: 15o, 25o, 30o (room temperature) and 35oC. It was found that temperature had no effect on anthocyanin content in any stage of fruit development. At all temperature levels, the anthocyanin content was increased accordingly and had the highest level at stage 6. Temperature affected on PAL activity at different stages. Levels of PAL activity decreased at the early stages and increased at the final stage of maturity except for fruits held at 25oC, PAL activity remained at a low level through stage 6, while fruit at 35oC had the highest level of PAL at stage 5.