Effect of heat treatments for fruit fly control on physical, chemical and sensory properties of exported papayas
1994
Saravadee Yoosaeng
Heat treatments were studied for disinfestation quarantine of papayas for export compared to control. They are forced-air dry heat (FADH) treatment and two-stage hot water immersion (HWD) treatment. For FADH, the samples were treated in hot air oven at 48.5+-1 deg C with 40-60 percent R.H. until fruit center temperature reached 46.5 deg C for 10 minutes. Time taken to complete this treatment was approximately 8 hours. For HWD, the samples were preheated in hot water at 42 deg C for 40 minutes for the first stage and were heated at 49 deg C for the second stage until fruit center temperature were 46.5 deg C for 10 minutes. Then the samples were hydrocooled immediately in water bath (23+-2 deg C) until fruit center temperature was below 30 deg C. Time taken to complete this HWD treatment was approximately 5 hours. FADH treatment gave the most percentage of weight loss, but had no influence on total soluble solid of papayas. For peel and pulp color, FADH and control contained not significant difference Hunter values, "L, a, and b", HWD had significantly more of green color and less of yellow and red. Heat treatment had no effect on electrolyte leakage, but had an effect on fruit firmness. HWD resulted in firmer tissue than control and FADH at day 4. Heat treatments also had no effect on pH, sugar profile (glucose, fructose), and acid profile (malic, citric, and succinic acids). The quantity of vitamin C in papayas with heat treatments decreased significantly from control. From descriptive analysis, the panelists ranked overall impression of all samples and showed that they liked control papayas and papayas treated with FADH rather than papayas treated with HWD at 95 percent level of significance.
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