Effect of frozen storage time on color and texture properties of cantonese sweet-paste-filling buns

Effects of frozen storage time on the color and texture properties of some quick frozen Cantonese sweetpaste-filling buns( lotus seed paste buns,red bean paste buns and egg yolk custard buns) stored at-18 ℃ from 0to 42 days by measuring the changes of color,water content,texture and specific volume were studied. Results showed that the storage time had no significant effect on the red( a*) of lotus seed paste buns and red bean paste buns( p > 0.05),while the two kinds of buns' lightness( L*) decreased and the yellow( b*) increased with the increasing of storage time.A marked decrease in L*value was observed up to 14 days of storage for lotus seed paste buns( p < 0.05).The lightness( L*) of egg yolk custard buns were not affected by the storage time as well,but the b*decreased and the a*increased. After storage for 7 days,the custard buns ' b*value decreased significantly( p < 0.05). The water contents of the buns were decreased in different degrees. As to the different layers of the buns,the crusts of red bean paste buns,the crumbs of egg yolk custard buns and the stuffing of lotus seed paste buns showed the maximum reductions of water contents respectively.As the storage time prolonged,the buns' texture characteristics of hardness and chewiness increased,while the adhesiveness,resilience,and springiness decreased.All the indexes of the texture properties changed significantly up to 42 days of storage( p <0.05).The frozen storage time had greatest effects on the increasing hardness and chewiness of lotus seed paste buns,and the decreasing adhesiveness of egg yolk custard buns. The red bean paste buns got the slowest properties changed.The total reductions of springiness and resilience among the buns had no marked difference.Also the storage time deteriorated the specific volume of the buns( p < 0.05),and the egg yolk custard buns were mostly affected.