Programmed Freezing Affects Texture, Pectic Composition and Electron Microscopic Structures of Carrots |
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Authors: | MICHIKO FUCHIGAMI NORIKO HYAKUMOTO KOICHI MIYAZAKI |
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Affiliation: | Authors Fuchigami and Hyakumoto are with the Dept. of Nutritional Science, Faculty of Health &Welfare Science, Okayama Prefectural University, 111 Kuboki, Soja, Okayama 719–11, Japan. Author Miyazaki is with Research &Development Center, Osaka Gas CO., LTD., Konohana-ku, Osaka, 554 Japan. |
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Abstract: | Raw and blanched carrots (3 min, boiling water) were frozen at ?2°C, ?3°C, ?4°C or ?5°C/min (final ?20°C or ?50°C) then thawed at 20°C or 100°C. Firmness of thawed raw carrots was: ?5°C > ?4°C > ?3°C > ?2°C/min. Effect of freezing rate on blanched carrots was less than that on raw carrots, but firmness of thawed carrots was not affected by final temperature of freezing. When raw carrots were thawed at 20°C, high methoxyl pectin decreased. Pectin decrease in blanched carrots caused by freezing was greater than that in frozen raw carrots. Effects of slow-freezing, programmed-freezing (slow + quick + slow) and quick-freezing showed quick freezing (—5°C/min) best for texture. As freezing rate decreased, drip increased. A wide difference among experimental samples in fine structure was revealed by cryo-scanning electron microscopy. |
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Keywords: | carrots programmed freezing pectic composition electron microscopy |
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