Freeze-thaw Stability Of Waxy Corn Starch Gel

Waxy corn starch?WCS?is the main product during the processing of waxy corn,which is applied to food industry widely as important food processing raw materials and additives because of its special structures and properties.At present,because of limited knowledge of WCS gel characteristics change mechanism during freeze-thaw cycle?FTC?,there is blindness in the application of WCS.In this research,WCS was selected as the research object by studying the physical and chemical properties of corn starch,which had excellent properties.In addition,the change law of physicochemical and structural characteristics of WCS gel during FTC was analyzed.Meanwhile,xanthan gum was added in WCS gel,which improved the freeze-thaw stability of the gel.At last,the application of corn starch and xanthan gum in frozen corn steamed sponge cake was studied.The results were listed below.The difference of physical and chemical properties between WCS and common corn starch?YM?was listed below.Transmittance of WCS was 50.75%—51.35%,which outclass the transmittance of YM?less than 17%?.Retrogradation of WCS was weak,which there was no precipitate during placing.However,percentage of liquid supernatant of YM was about 60%-75%after placing 48 h,then remained unchanged.The solubility and swelling degree of corn starch gradually increased with the increase of temperature.The solubility and swelling degree of WCS was higher than YM between 60?and 70?.WCS completely dissolved in water,and there was no precipitate after centrifugation above80?.Peak Viscosity,Trough Viscosity and Breakdown Viscosity of WCS were higher than YM.However,Final Viscosity,Setback Viscosity and Pasting Temperature were lower than YM.The relationship between physical and chemical properties and freeze-thaw stability of WCS gel was confirmed,which by analyzing the change of its physical and chemical properties during FTC.WCS gel displayed ultra-strong ability of holding water after the first FTC,and%syneresis of WCS2was 5.75%.However,YM gel had the weakest ability to hold water,and%syneresis was more than 50%.Hardness and%retrogradation of starch gels gradually increased with the increase of FTC,and there was a significant difference between 1,3,5 FTCs.Hardness and%retrogradation of WCS gel were 45g-100 g and 46%after 5 FTCs,respectively.However,hardness and%retrogradation of YM gel were440 g and 83%after 5 FTCs,respectively.Tangent of lose angle?tan??of starch gels gradually decreased with the increase of FTC,and tan?of WCS gel was always higher than tan?of YM gel.The structure of starch gels changed obviously after 5 FTCs.The matrix surrounding pores of YM gel was thick and typical.However,the matrix surrounding pores of WCS gels was thin and atypical.It illustrated that the freeze-thaw stability of WCS gel was better than YM gel.The influence of xanthan gum?XG?on WCS gel freeze-thaw stability was studied by FTC.At the same FTC,%syneresis and%retrogradation gradually decreased with the increase of XG content.After1,3,5 FTCs,the%syneresis of WCS gel which containing XG decreased by 5.63%,33.77%and 8.48%,respectively.And%retrogradation decreased by 6.88%,14.86%,and 23.7%,respectively.After FTC,the extent of tan?reduction of WCS gel which containing 0.4%XG was smallest,and tan?was hovered around 0.5.However,the extent of tan?reduction of WCS gel which no XG was maximum,and tan?decreased from 2.4 to 1.4.?T_2?2?of WCS gel which containing 0.4%XG was about 0-400ms during FTC.Moreover,its?T_2?2?was smallest all the time at the same FTC.However,?T_2?2?of WCS gel which no XG was about 250-800 ms during FTC.Pasting Temperature,Setback Viscosity and Breakdown Viscosity gradually decreased with the increase of XG content.However,Peak Viscosity,Trough Viscosity and Final Viscosity gradually increased.After 5 FTCs,the extent of damage of WCS gel wall was decreased gradually with the increase of XG content.It illustrated that XG improved the freeze-thaw stability of WCS gel.Using microwave to preparing corn steamed sponge cake,and adding YM,WCS,XG into steamed sponge cake,then analysis the influence of additives on freeze-thaw stability.After FTC,carbon dioxide production of yeast in corn batter decreased.After 4 FTCs,carbon dioxide production of corn batter which containing no additive,YM,WCS,XG,and mixture of XG and WCS decreased by 29.68%,28.74%,27.10%,26.15%,and 22.25%,respectively.G'and G''of different corn batter gradually decreased with the increase of FTC,and the size of variation range were both no additive>YM>WCS>XG>mixture of WCS and XG.The content of immobile water of corn batter decreased with the increase of FTC.After 4 FTCs,the content of immobile water of corn batter which containing no additive,YM,WCS,XG,and mixture of XG and WCS decreased by 7.49%,5.16%,4.38%,3.73%and 2.93%,respectively.Specific volume and resilience of steamed sponge cake gradually decreased with the increase of FTC.However,hardness and chewiness gradually increased with the increase of FTC.After 4 FTCs,specific volume of steamed sponge cake which containing no additive,YM,WCS,XG,and mixture of XG and WCS decreased by 41.75%,40.37%,40.81%,39.79%and 33.57%,respectively.Resilience decreased by 22.4%,22.5%,19.7%,18.7%and 16.3%,respectively.Hardness increased by 205%,167%,177%,153%and 145%,respectively.Chewiness increased by 234%,210%,197%,207%and 182%,respectively.It illustrated that YM,WCS and XG improved the quality of frozen corn steamed sponge cake,and mixture of XG and WCS was strongest.They can be used as food additives in frozen corn steamed sponge cake.