Effect Of Food Gums Combined With Dry Heat Treatment On Properties Of Potato Starch And Its Application

With the potato becoming an important food crop in China,the application and development of potato starch has also developed rapidly.Potato starch has its own advantages like it has low gelatinization temperature and starch paste has high viscosity,so it is widely used in the food industry.Potato vermicelli is an Chinese traditional food made of potato starch,but the alum contained in potato vermicelli may cause harm to human health,so it is necessary to develop alum-free vermicelli to replace the traditional vermicelli.In addition,potato starch is too sensitive to heat and shear,and the mechanical strength of starch paste is low,so its application in the food industry is limited.In this study,in order to improve the edible quality and processing properties of potato vermicell,three different food gums(guar gum,sodium carboxymethyl cellulose and xanthan gum)are added to potato starch at a certain ratio,combined with dry heat treatment to produce alum-free vermicelli.Furthermore,the physical and chemical properties of mixture as well as the mechanism of food gum combined with dry heating affecting potato starch is investigated to provide a theoretical basis for starch modification and its application in the food industry.The results exhibited as followed:1. Firstly,the single factor experiment was used to determine the optimal amount of guar gum,CMC and xanthan gum by investigating the edible quality of potato vermicelli such as absorbance value,cooking loss,TPA,tensile strength and sensory evaluation.Subsequently,three different food gums were mixed and the orthogonal experiment showed the optimal mixing ratio was 0.6%guar gum,0.4%CMC,0.3%xanthan gum.Then the system was treated with dry heating.Finally,it was found that the alum-free vermicelli was safer and better than the traditional alum vermicelli.2. In the process of gelatinization of potato starch,food gum could refract and reflect light,which reduced the transparency of starch paste,but dry heat treatment did not significantly affect the transparency of the paste.Moreover,because food glue could compete with starch for water and dry heating might reduce the content of water in the system,so food gum combined with dry heating could inhibit the swelling power of potato starch.As the degree of swelling power of starch decreased,the amount of dissolved amylose was reduced,so the solubility of starch was also decreased.3. The RVA showed that adding food gum increased the gelatinization temperature of the mixture,but dry heating decreased the gelatinization temperature because of the low content of moisture.On the other hand,food gum combined with dry heating enhanced the thermodynamically incompatible phase separation phenomenon,which increased the peak viscosity of system,and the treatment strengthened the the crosslinking between the food gum and starch,making it more resistant to shear,so the breakdown value was declined.And the system was more likely to recrystallize,the setback value was improved.In thermodynamic experiment,it was found adding food gum increased T_o,T_pand T_c,and also increased the enthalpy of gelatinization?H.However after dry heating,T_o,T_p,T_cand?H were decreased because of the destruction of crystal structure of potato starch.4. In the process of retrogradation of potato starch,food gum combined with dry heating promoted the transformation of unstable starch structure towards a more uniform and stable structure,so the retrogradation was enhanced.But during this process,softer starch gel was formed,so the gel strength was reduced.In the thawing and freezing experiment of starch gel,adding food gum combined with dry heating declined syneresis of starch gel since the ice crystals had little effect on the structure after melting,so the stability of freezing and thawing were better.5. The force in the starch gel system was mainly hydrogen bonds while the food gum-starch gel system was no longer dominated by hydrogen bonds,since other relevant forces existed like electrostatic interaction or crosslinking interaction between starch and food gum.In addition,the infrared spectrum showed that new characteristic peaks appeared in the food gum-starch system,indicating that new ester bond was formed in the system.And the SEM image showed that food gum combined with dry heating significantly improved the density of starch gel microstructure.6. In the dynamic rheology experiment,adding food gum combined dry heating increased the G'and G''while reduced tan?,which indicated the elasticity of the starch system was dominant.In the static rheological experiment,the treatment increased the consistency coefficient K,decreased the fluid index n and the hysteresis ring area,enhanced the stability of the starch paste and made it more resistant to shear.In the vitro digestion,food gum assisted dry heating reduced the content of RDS,while increased the content of SDS and RS of potato starch.