Mangosteen Fruit Quality and Color Development

2.2 Mangosteen Fruit Quality and Color Development

The quality of mangosteen Garcinia mangostana L. fruit is measured not only by external factors such as color, shape, size, skin blemishes, latex staining and insect damage, but also by internal factors such as translucent flesh, yellow gummy latex and hardening pericarp which are also very important for consumer acceptance Teerachaichayut et al., 2006. Fruit color is a major criterion used to judge maturity and for grading of mangosteen fruit. The fruit are usually harvested at different stages according to colour, from light greenish yellow with scattered pink spots to dark purple. After harvest, the purple color continues to develop very quickly. For high fruit quality, the minimum harvest color stage is that of distinct irregular, pink –red spots over the whole fruit. If fruit are harvested with a light greenish yellow with scattered pink spots, the fruit do not ripen to full flavor Tongdee and Suwanagul, 1989; Paull and Ketsa, 2004. ` The color of mangosteen Garcinia mangostana L. fruit changes from green to purple black after harvest as the fruit ripens, and is used as a quality guide for growers and consumers. During the postharvest period, hue angle values and pericarp firmness decreased significantly, while soluble solids contents increased. Anthocyanin contents in the outer pericarp were higher than in the inner pericarp and increased to a maximum at the final color stage Palapol et al., 2009. Commercial production has been limited by slow growth, long juvenile periods of 10-15 years and short shelf-life of fruits when mature Wiebel et al., 1992. Keeping quality of mangosteen fruits is longer compared to other tropical fruits. Long storage of fruits leads to hardening of pericarp and opening of fruit become difficult Radha et al., 2007. Palapol et al. 2009 indicated that fruit harvested at stage 1 developed rapidly to the purple black stage stage 6 within 9 days with color development from stage 5 to stage 6 being slower than other stages. During color development, the a b value increased slightly from stage 1 to stage 3, and then increase sharply to stage 6. The increase in the a b values correlated well with color development. When fruit at the six different stages of maturity were harvested and kept at 25 o C, each stage fully developed to the purple black stage 6. No matter at what stage the fruit were harvested, they all ripened, and no significant differences in sensory evaluation and fruit quality, 5 including hue angle values, firmness, soluble solids content SSC and titratable acid TA, when the fruit were accessed at stage 6 Palapol et al., 2009. Calyx freshness of mangosteen fruit strongly affects quality value during periods of storage. Fresh mangosteen fruit has green and fresh calyx, but the freshness becomes brown after a few days. Research conducted by Suryanti et al. 1999 showed that mangosteen fruit harvested at green and fresh peel with purple spots and calyx freshness could maintain its freshness for 6 days of storage. Optimum temperature for retention of peel and calyx color is 10 o C Azhar, 2007. Ekaputri 2009 found that treatment of chitosan 1.5 could retain color of mangosteen peel and calyx. Beeswax 6 treatment and BAP 20 ppm could retain calyx color for 21 days after treatment, but it started wrinkling after 15 days of treatment Pratiwi, 2008. Anggraeni 2008 reported that combination of 0.01 mm- thick plastic wrapping and chitosan coating 1.5, and plastic wrapping with wax Britex gave a better effect on inhibiting changes of peel and calyx color for 30 days of storage at room temperature, and 35 days at temperature 15 o C.

2.3 Causes of Mangosteen Fruit Hardening