Effects Of Bacterial Cellulose On Retrogradation Of Rice Starch Gels

Starch is the major food source in nature and plays a key role in the food industry.Although the retrogradation of starch is still a bottleneck which restricts the development of starchy food.The addition of bacterial cellulose can obviously improve the physiochemical properties and storage stability of starch;and reduce the water loss of starch gel.Therefore,the effects of bacterial cellulose(BC)on the gelatinization,retrogradation and freeze-thaw stability of rice starch(RS);effects of dynamic high-pressure homogenization modified bacterial cellulose on retrogradation of rice starch were studied by rapid viscoanalyzer(RVA),differential scanning calorimetry(DSC),X-ray diffraction(XRD),scanning electronic microscope(SEM)and texture profile analysis(TPA),dynamic high-pressure homogenizer,laser particle size analyzer and fourier infrared spectroscopy analyzer(FTIR).The main conclusions of this research were as follows:The results from RVA showed that addition of BC significantly decreased the break down and setback values,which suggest that the short-retrogradation of RS was inhibited.The results from DSC curves and XRD showed that retrogradation enthalpy and recrystallinity of RS was reduced 4.9J/g,5.33% with the addition of BC from 0% to 20%.SEM images circumstantiated that BC can indeed compete with the RS granules for water molecules,consequently inhibited the swelling of the RS granules and subsequent retrogradation of RS.The overall results demonstrate the remarkable inhibitory effects of BC on the retrogradation of RS.Therefore,BC can be used as a new type of starch retrogradation inhibitor in starchy food.The study herein verified the effects of BC on freeze-thaw stability of RS gels that depended on the concentrations of BC by a variety of methods.BC was shown to be an effective agent for the reduction of recrystallinity,the spongy structure formation,and for limiting the increase in gel hardness of RS gels after five freeze-thaw cycles.BC could effectively retard the retrogradation of rice starch gels.This study showed that BC could be a useful additive for preserving quality in frozen rice starch-based food products.The results showed that dynamic high-pressure homogenization could effectively reduce the particle size of BC,improve the stability of suspension.Addition of modified BC to RS decreased breakdown and setback value,indicating modified BC may be a candidate for increasing stability of RS paste and restraining the short-term retrogradation of RS gels.The DSC results showed that modified BC significantly reduced the retrogradation enthalpy of RS after being stored at 4 ℃for different days.XRD results suggested that recrystallinity of RS was reduced 4.54% for the modified BC pressure increase,and this finding agreed with the DSC results.SEM images circumstantiated that the cavities of RS gels distributed evenly and resulted in denser structure for modified BC pressure increase.The overall results demonstrated that dynamic high-pressure homogenization may be an effective physical method to improve the physicochemical properties of BC,and modified BC may be a great candidate for restraining retrogradation of RS gels.