Maturity index and respiratory pattern indicate optimal harvesting time and post-harvest handling of jatropha curcas Linn fruits

Abstract

The main harvesting and post-harvest problem of jatropha is that any single branch the fruits ripens at different times. It leads to laborious and time consuming harvesting as farmers have to select the ripe fruits only or fruits have to be harvested manually at regular intervals (Heller, 1996; Biswas et al., 2006). Therefore, this problem has been highlighted in many publications that may jeopardise the economic viability of production of this crop (GEXSI, 2008; Hambali, 2008). Jatropha fruits are still harvested by hand in small and plantation scale farms. Mechanical harvesting of jatropha is considered to be impossible due to the non uniformity of fruit ripening. In many crops, maturity or ripening index is developed as measurement that can be used to determine or estimate when the particular commodity is mature and ready to be harvested. High CJCO content and fruit color changes after elapsed days from full bloom have been recommended as indication of harvesting time in Jatropha by many researchers; Heller (1996) and Hambali et al. (2007) recommended 90 days after anthesis or black dry fruits; Santoso et al. (2008) recommended 55 days after anthesis or fully yellow fruits, Wanita and Hartono (2008) recommended 45 days after anthesis of yellow fruits and Annarao et al. (2008) recommended 37 days after anthesis or just before drying. Varying and contradict recommendations indicate a need for development of maturity index in this crop. In general, fruits can be classified as either climacteric or non-climacteric based on their respiration pattern during ripening. Climacteric fruits display a characteristic peak in respiratory activity during ripening. It is interesting to note that climacteric fruits, such as banana, tend to ripen rapidly. It has led to the regulation of respiration as a possible target of biochemical manipulation of shelf life. In contrast, non-climacteric fruits, such as pineapple, simply exhibit a gradual decline in their respiration during ripening. They have to be harvested at optimal stage of maturity on the tree. However, no information is available on the Jatropha’s respiration pattern during ripening. Therefore, the main objective of this study was to determine the maturity index and its physico-chemical characteristics and to better understand the fruit respiration pattern during storage.