Blackwell Publishing Journal Backfiles 1879-2005
Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
Process Engineering, Biotechnology, Nutrition Technology
SUMMARY— The effect of processing variables on the cell structure and physical characteristics of carrots were determined. The phloem portion of fresh carrots was subjected to one of the following treatments: blanching; cooking for 10 min; freezing at 0°F, −30°F or −320°F; freeze drying, compressing after freeze drying at approximately 1500 psi. Carrots at each treatment were tested for: (1) texture by means of the Ailo-Kramer Shear Press; (2) water holding capacity by centrifuging at 500, 1000, 1500, 2000 and 2500 rpm; (3) histological changes by microscope observation of the tissue structure. Results indicate that among all treatments, freezing temperature is the most critical factor affecting the cell structure of the carrots. Freezing at 0°F or −30°F results in considerable disruption of the cellular structure, whereas it was minimal at −320°F. Carrots frozen at −320°F showed firmer texture as well as higher water holding capacity than the rest. Significant correlation coefficient was established between the shear press values and percent weight loss measured by centrifugation. This suggests that the latter may be used as an objective test for measuring textural changes in processed carrots and perhaps other foods.
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