EFFECTS OF RAW MATERIALS AND PROCESS VARIABLES ON THE HEAT PENETRATION TIMES, FIRMNESS, AND PECTIC ENZYME ACTIVITY OF DICED TOMATOES (HALLEY BOS 3155 CV) |
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Authors: | WENDY H MA DIANE M BARRETT |
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Affiliation: | University of California-Davis Food Science and Technology Department One Shields Way Davis, CA 95616 |
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Abstract: | The effects of raw materials and process variables on the heat penetration times into diced tomatoes (Halley Bos 3155 cv) were evaluated. Variables included dice size (1.27 and 2.54 cm), maturity at harvest (red and red+2 weeks), and processing temperature (88 and 92C). Heat penetration times between dice sizes were significantly different, but not between maturities or processing temperatures. Tomatoes were also evaluated for firmness, pectin-methylesterase (PME) and polygalacturonase (PG) activities. Half-inch size diced tomatoes were processed at 88 and 92C, and evaluated for firmness using the shear-compression method. Firmness decreased to 60% of the initial raw firmness from 8.8 × 105 to 5.3 × 105 g-mm after 15 s at 88C, and to 50% from 8.8 × 105 to 4.4 × 105 g-mm after 15 s at 92C. Diced tomato firmness showed a slight firming trend after 150 s at both temperatures. PME was inactivated after 45 s, while 5% residual PG activity remained after 3 min. |
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