Effects Of Proanth Ocyanidins On The Physicochemical Properties And Digestibility Of Rice Starch

Rice starch is widely used in the food industry due to its rich source,low price,and ability to impart various functional properties to foods.However,rice starch is often not found in food alone,but often coexists with other compounds.Polyphenols are one of them.In this paper,using rice starch as raw material,adding proanthocyanidins to rice starch,and the influence of physicochemical properties of rice starch was studied by means of modern instruments.The results showed that proanthocyanidins could not only improve the physicochemical properties of rice starch,extend the shelf life of starch products,but also slow down the rate of increase of blood glucose after rice starch digestion to a certain extent.At the same time,the in vitro simulative digestion process of proanthocyanidins-rice starch system was studied.The results showed that proanthocyanidins could significantly inhibit the hydrolysis of rice starch and provide theoretical guidance for the future production and application of rice starch and its products in industry.The proanthocyanidins were added to the rice starch according to 0%,5%,10%and 15%of the dry base of the rice starch.First,the gelatinization and rheological properties of the mixed system were investigated by a rapid viscosity analyzer,a differential scanning calorimeter,and a rotary rheometer.The results showed that with the increase of the amount of proanthocyanidins added,the peak viscosity,valley viscosity and final viscosity of the mixed system all increased,and the disintegration value decreased.Compared with the control group,the initial temperature,the peak temperature and the termination temperature all decreased,and the gelatinization enthalpy decreased significantly,indicating that the addition of proanthocyanidins promoted the gelatinization of rice starch.The addition of proanthocyanidins did not significantly change the storage modulus G?and loss modulus G"of the rice starch system,but with the increase of the amount of proanthocyanidins added,thixotropy ring area of the rice starch decreased,It shows that the shear stability of the mixed system is better.Secondly,the short-term retrogradation and long-term retrogradation of rice starch-proanthocyanidins mixed system were measured by Fourier transform infrared spectrometer,X-ray diffractometer,differential scanning calorimeter,texture analyzer,low field nuclear magnetic resonance and scanning electron microscope.The addition of proanthocyanidins can significantly reduce the recovery value of rice starch.The texture results showed that the hardness,gumminess,and cohesioness of the gels after the addition of proanthocyanidins decreased significantly,and the adhesiveness increased.The results of LF-NMR experiments showed that compared with the control group,the rice starch system with proanthocyanidins had a slower rise in the bound water T₂₁ and a slower decrease in the free water T₂₂,indicating that proanthocyanidins have good hydrophilicity,and the water molecule mobility in the system.By SEM,it was found that the addition of proanthocyanidins made the structure of rice starch porous and porous during storage.DSC experiments showed that the addition of proanthocyanidins decreased the retrogradation value and retrogradation rate of rice starch system.In addition,the XRD results also showed that the rice starch system stored for 7 days after the addition of proanthocyanidins was more dilute than the B-type peak of the control group.Weak and lower crystallinity,the ratio of the peak height of the absorption peak at 1047 cm^-1 and 1022 cm^-1 of the FTIR of the rice starch system gradually decreased.This shows that procyanidins can inhibit retrogradation of rice starch.Finally,the effect of on the digestive properties of rice starch systems were investigated by simulating in vitro digestion experiments.The experimental results show that the addition of proanthocyanidins can inhibit the rate of glucose production during the digestion of rice starch.In addition,the order of the addition of proanthocyanidins also has a certain influence on the digestion of starch system.The proanthocyanidins,which account for 15%of the dry basis weight of starch,were first mixed and gelatinized with rice starch,and then enzymatic hydrolysis was added.After the cyanidin was mixed with the enzyme,hydrolysis was then added to the gelatinized starch,the release rate of glucose was slower.In the process of digestion,proanthocyanidins can interact with enzymes in the system and interact with rice starch.