Analysis About The Phenomenon Of The White Edge's Frozen Dumplings' Reason After Cooking And The Control Method Research

Frozen dumpling was indispensable food in people's diet in China.In order to explore the white reason and improve the edible quality of quick-frozen dumplings after cooking,this paper took the white edge's frozen dumplings as our research target,we studied the chemical and physical characteristics of white part of the dumpling's skin,analyzed the reason of the white part of the dumpling's skin after cooking,which through astral instrument,spectrophotometer,scanning electron microscopy(SEM),rapid viscometer(RVA),etc.On this basis,through the cause of the white quick-frozen dumpling skin,we researched the different food additives on the the influence of quick-frozen dumpling skin's bibulous rate,gelatinization temperature,gelatinization degree and sensory quality.The main conclusions were as follows:(1)We compared the frozen dumplings at the edge of the white frozen dumplings after cooking with not pale,and studied on the water content,protein content,starch and amylose content,water absorption,starch crystallinity and gelatinization degree and so on.The results showed that,there was no difference between the protein content,starch,starch crystallinity of the white edge's frozen dumplings' skin and the frozen dumplings' skin which was not white,the amylose content was not consistent with the law.There was a significant difference(P<0.01)between the moisture content and gelatinization degree of the white edge's frozen dumplings' skin and the frozen dumplings' skin which was not white.The moisture content and degree of gelatinization of the white edge's frozen dumplings' skin was significantly lower than the edge of the frozen dumplings' skin which was not white.When water absorption rate of the dumpling skin was less than 45.94%,the dumplings was white after cooking.When the water absorption of dumpling skin was higher than 47.21%,the dumpling was not white after cooking.(2)After using Matlab to process the SEM image,the pore area of the white dumplings' skin was the largest and the degree of starch gelatinization was the highest,the next was white dumpling skin,the pore area of raw dumplings' skin was minimum,that starch was in the state of not gelatinized.Under the same electron microscope multiples and photo resolution,the microstructure of the white edge's frozen dumplings' skin had starch particles which obviously not entirely gelatinized.From the aspect of texture characteristics and quality evaluation,we can found that the edible quality of the white edge's frozen dumplings was far worse than none-white edge of boiled dumplings' quality.The white phenomenon of cooked frozen dumplings' skin may be due to the low moisture content,and not entirely gelatinized starch after cooking.To solve the whitening phenomenon of boiled quick-frozen dumplings,we can reduce the loss of water during storage,improve the moisture content and moisture holding capacity of dumpling skin,increase the paste degree,and reduce the gelatinization temperature of dumpling skin and so on.(3)We added different kinds of food additives to flour and made the wrappers.On the basis of single factor,we selected the content of xanthan gum,sucrose ester,compound phosphate and acetylated starch as the independent variable,using the Box-Behnken center combination principle,then we used the bibulous rate,gelatinization temperature,gelatinization degree and sensory score of dumpling skin for response values to proceed the response surface analysis.Results showed that when the content of xanthan gum,sucrose ester,compound phosphate and acetylated starch were respectively 0.3 %,0.1%,0.5%,4%,the bibulous rate of quick-frozen dumplings' skin was 63.48%,the gelatinization temperature was 65.73?,the gelatinization degree was 88.01%,the sensory score was 90.6,the result and the predicted values were basically the same.The minimum and maximum water absorption of boiled dumpling skin that was not white were 47.21% and 58.61%.Under this additive,the water absorption rate of dumpling skin was 63.48%,and which was more than 47.21% and 58.61% respectively.This indicated that the dumplings were not whitened after cooking from the theoretical value.(4)We studied the difference between the microstructure and water loss rate of the frozen dumpling skin after adding the additive and the dumpling skin which was not added additive.At the same time,the gelatinization temperature of the dumpling skin powder was also measured.The results showed that form the microstructure of dumpling skin with additive,we can found that the starch in the raw dumpling skin was embedded in the network structure of the additive and protein,the whole dumpling skin's structure was relatively uniform and solid,the formation of the hole was also more uniform,the degree of gelatinization was also more complete,and water loss rate also significantly reduced.After adding the additive,the gelatinization temperature of the dumpling skin sample powder also decreased.