LENGTHENING THE PRESERVATION TIME OF FRESH LONGAN BY LOW TEMPERATURE, FIRM PACKAGING AND CHEMICAL TREATMENT

Abstract

The Sulfur dioxide treatment for longan before the low temperature preservertation has been done popularly, but rashly. In this study, we investigated the effect of SO2 to the ripeness and time waiting for transport. 85% and 24 hours are the ripeness of longan and the time for transport was chosen. The temperature used to preserve is 5°C. The respirating handling is realized by either,corrugated boardpacking or both of them or by polysaccharide membranes, such as CMC, chitosant... with polimer membranes. This method keeps the longan fresh in 45 days, 9 times longer in comparing with the case of no packing and in natural condition. Other chemical agent, such as sorbat sodium, hypocloride sodium...can also be used to keep the longan in shorter time 10-25 days.