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Changes in temperature, texture, and structure of Konnyaku (Konjac Glucomannan gel) during high-pressure freezing

Author:
Teramoto, A., Fuchigami, M.
Source:
Journal of food science 2000 v.65 no.3 pp. 491-497
ISSN:
0022-1147
Subject:
gels, konjac mannan, freezing, pressure, temperature, texture, ultrastructure, glucomannans, water content, ice, strains
Abstract:
To determine the effects of high-pressure-freezing, changes in temperature, texture, and structure of konnyaku (a gel with high water content) were measured during freezing for 60 min at 0.1 to 700 MPa and -20 degrees C. During freezing at 0.1, 100, 500, 600, and 700 MPa, exothermic peaks were detected (konnyaku froze). However, at 200 to 400 MPa, exothermic peak was not detected and temperature rose when pressure was released at -20 degrees C; the supercooled konnyaku froze by pressure-shift-freezing. The coarse gel network observed in unfrozen konnyaku was compressed by freezing due to formation of ice crystals. The rupture stress increased and strain decreased in all frozen konnyaku. High-pressure-freezing was ineffective in improving the texture of frozen-then-thawed konnyaku.
Agid:
1394990