The Effect Of Different Aging Temperature And Time On The Multi-scale Structure And Physical And Chemical Properties Of Debranched Pea Starch

Processing and storage conditions affect the retrogradation of starch,which is closely related to the quality of food.In the present study,pea starch was used as raw materials and then was debranched by pullulanase(30 U/g).The paste was cooked in an autoclave at 121? for 20 min,the obtained starch paste was cooled to room temperature and retrograded for 6 h,12 h,24 h,48 h,72 h,at both 4oC and 25?,respectively.The structural changes and retrogradation behavior of processed and retrograded pea starch were determined by scanning electron microscopy(SEM),X-ray diffraction(XRD),solid carbon nnuclear magnetic resonance spectroscopy(13CNMR),Fourier transform infrared spectroscopy(FT-IR),and snall Angle X-ray scattering(SAXS).Thermal characteristics and gelatinization properties of those samples were studied by Differential scanning calorimeter(DSC)and rapid visco-analyzer(RVA).Swelling power(SP)and Solubility(S)were analyzed at the same time.The results were as follows:(1)Different retrogradation temperature and storage time had significant influence on the structural changes and retrogradation behavior of processed and retrograded pea starch.Scanning electron microscopy(SEM)showed that the integrity of all the debranched and retrograded pea starch granules which formed irregular shapes was destroyed;A mixture of B-and V-type crystalline polymorph was observed by XRD for all processed and retrograded pea starch;Small Angle X-ray scattering(SAXS)results showed that the crystal layers of all processed and retrograded pea starch were destroyed.A continuous increase in relative crystallinity(C1 and C2),degree of order(1047/1022 cm-1)and degree of double helix(995/1022 cm-1)measured by XRD,13CNMR,and FT-IR,respectively,was observed during the initial retrogradation period of pea starch for 6-48 h at 4? and for 6-24 h at 25?,followed by a decreased trend during the subsequent storage time from 48 h to 72 h at 4?,and from 24 h to 72 h at 25?.(2)Different retrogradation temperature and storage time had significant influence on the physicochemical properties of the processed and retrograded pea starch.A continuous increase in ?H2 measured by DSC was observed during the initial retrogradation period of pea starch for 6-48 h at 4? and for 6-24 h at 25?,followed by a decreased trend during the subsequent storage time from 48 h to 72 h at 4?,and from 24 h to 72 h at 25?.The results determined by RVA showed that the RVA viscosities of native pea starch were relatively higher than that of all processed and retrograded pea starch;The solubility for processed pea starch stored at 4? were generally higher(P<0.05)than those stored at 25?,which was negatively correlated with double helix content by 13CNMR,this could be explained by the fact that the double helix prevents starch from dissolving.Swelling power for the processed and retrograded pea starch stored at 25? were higher(P<0.05)than other samples,which was negatively correlated with the PPA values measured by 13CNMR.This suggested that the more amorphous starch,the higher the degree of expansion.The comprehensive analysis in this study generally showed that different retrogradation temperature and storage time had significant influence on the structural changes,retrogradation behavior and physicochemical properties of the processed and retrograded starch.The processed and retrograded starch stored at 4oC for 48 h and stored at 25? for 24 h can be used to produce retrograded products with heating stability and improve the quality of the processed food.The in-depth understanding of these structural changes during different retrogradation conditions would be of great interest to help the food industry to design novel starch-based foods with desired techno-functional properties.