EFFECT OF ULTRA-HIGH PRESSURE ON THE QUALITY AND SAFETY OF FRESH-CUT LONGAN FRUIT

Peeling and cutting increased the area of injured tissue available for microbial proliferation and biochemical deterioration reduced the shelf-life as compared to intact longan fruits. Thereby, it is necessary to develop a suitable technology to extend the shelf life for the commercial use of fresh-cut longan fruit. In this paper, the effects of ultra-high pressure (UHP) on the quality of fresh-cut longan fruits were studied. The slices of fresh-cut longan fruit were treated with different pressure for 10 min and then were stored at 4°C for 9 days. The effect of UHP on micro-organisms, sensory characteristics, total soluble solids, titratable acidity and ascorbic acid of fresh-cut longan fruit were determined during storage. UHP of 400 MPa was able to reduce the number of bacteria on fresh-cut longan fruit by 4.47 log₁₀ cfu/g and no bacteria was assayed on fresh-cut longan fruit treated with 600 Mpa before storage. After 9 days of storage, the total bacteria counts on fresh-cut longan fruit treated with 400 and 600 MPa were 1.55 log₁₀ cfu/g and 0 log₁₀ cfu/g, respectively. The UHP treatment of 600 MPa significantly blocked the browning of fruit slices and microorganisms growth and maintained the quality of fresh-cut longan fruit. The UHP treatment could result in microbial destruction and product stabilization without affecting the sensory characteristics. So, UHP was an alternative potential nonthermal preservation method for pasteurization of fresh-cut longan fruit.