• Korean Journal of Food Science and Technology
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• v.26 no.4
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• pp.370-374
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• 1994

The effect of water activity(Aw) and storage temperature on retrogradation of pregelatinized corn starch was investigated at various temperature of $4^{\circ}C$, $20^{\circ}C$ and $30^{\circ}C$. Samples stored at different water activity, i.e., 0.43, 0.52, 0.75, 0.83, 0.88 and 0.93 by means of saturated salt solutions. The rate of retrogradation was determines. by enzymic digestibility, and evaluated by Avrami equation. The degree of retrogradation during storage showed a great difference around Aw 0.8. At Aw 0.52 and 0.75 at all temperatures, retrogradation occurred slightly. The effect of water activity on retrogradation was much greater at $4^{\circ}C$ than 300. And at Aw 0.43, the degree of retrogradation after 3-week storage was smaller than 3.9%. The critical water activity of retrogradation was inferred as Aw 0.43. At each temperature, the degrees of retrogradation of gelatinized corn starch after 24-day storage were 30% at Aw 0.8 and Aw 0.9, and greater than 50% at the Aw above 0.9. At Aw below 0.8 the degree of retrogradation was about 20%. The rate constants of retrogradation according to Aw showed small differences at $20^{\circ}C$ and $30^{\circ}C$, but showed a great difference at $4^{\circ}C$. The value of exponent of Avrami was 1.0 regardless of temperature and water activity. And the rate constants of retrogradation increased with increasing Aw, but decreased with increasing temperature.