Effects Of Plant Proteins On The Physicochemical Properties Of A-,B-,and C-Crystalline Starches

This article selects six plant proteins(rice protein,corn protein,wheat protein,soybean protein,potato protein,and pea protein)to interact with three crystal forms of starch(A crystal form:rice starch,B crystal form:potato starch,and C crystal form:pea starch)to elucidate the mechanism of the interaction between protein and starch.Firstly,this article explores the influence of plant proteins on the structural characteristics of A-,B-,and C-crystalline starch.Preliminary exploration was conducted on the changes in the structure and apparent effects of starch crystal form differences on the protein starch mixture system.The mixed system formed by protein and starch,as well as the particle morphology,crystal structure,relative crystallinity,particle size distribution,and short range ordered structure of the original starch,were measured.The results showed that after the hydrothermal interaction betweenprotein and starch,the particle size of the mixed system showed an increasing trend,indicating an interaction between protein and starch.However,the X-ray diffraction results showed that this interaction did not change the crystal form of starch.After the interaction between protein and starch,aggregation occurs,and the polarized cross of some starch particles becomes dark or even disappears.The results of Fourier transform infrared spectroscopy showed that protein and starch interacted through non covalent bond,and the ratio of rice starch at 1047/1022 cm-1 was 1.087,which was higher than that of protein after interaction,indicating that the order of crystal was enhanced,the order of double helix was improved,and the strength of hydrogen bond was improved,while potato starch and pea starch showed the opposite trend.Secondly,the effects of plant protein on functional properties such as starch expansion coefficient,solubility,amylose overflow rate,water holding capacity,freeze-thaw stability,thermodynamic properties,and gelatinization properties were studied before and after the action of A-,B-,and C-crystalline starch.The results showed that the following changes occurred after the interaction of A-,B-,and C-crystalline starch with plant proteins:(1)The solubility basically increased,while the expansion coefficient decreased.(2)The amylose overflow rate decreased significantly.The amylose content of rice starch decreased from 20.07%to a minimum of 16.10%,the amylose content of potato starch decreased from 16.68%to 14.42%,and the amylose content of pea starch decreased from 19.43%to 16.43%.This indicates that the addition of protein has an inhibitory effect on the overflow of amylose.(3)The water holding capacity of rice starch and potato starch decreased,and the water release rate increased,while the water holding capacity of pea starch increased,and the water release rate showed a downward trend.(4)The initial gelatinization temperature,peak temperature,and termination temperature of the mixed system all show an increasing trend,making starch gelatinization more difficult,indicating an increase in thermal stability.The gelatinization temperature range of rice starch is about 60 ℃ to 72 ℃,with the smallest range span.The enthalpy value continuously decreases from 3.85 J/g,and the enthalpy value is the lowest among the three types of starch;The gelatinization temperature range of potato starch increased from 51℃ to about 69℃,and the enthalpy value increased continuously from 6.69 J/g.The range of temperature and enthalpy values was the largest;The enthalpy value of pea starch decreased from 6.07 J/g to a minimum of 4.83 J/g,and the gelatinization starting temperature was 62.43℃,which was the highest among the three starches.(5)The gelatinization temperature of the mixed system significantly increased,while the viscosity value,disintegration value,and retrogradation value showed a basic downward trend.The increase in gelatinization temperature indicates an increase in structural stability.The decrease in retrogradation value indicates that starch is not prone to aging,and the addition of protein inhibits short-term retrogradation of starch.Finally,the digestion characteristics and in vitro hydrolysis rate curves of plant proteins treated with A-,B-,and C-crystalline starch were studied and compared.Correlation analysis was conducted on factors that may affect starch digestion characteristics,such as amylose overflow rate,average particle size,volume average particle size,surface area average particle size,infrared ratio at 1047/1022 cm-1,and infrared ratio at 1022/995 cm-1.The results showed that the addition of protein could significantly reduce the content of rapidly digestible starch and the digestibility of starch.The content of rapidly digestible starch in rice starch decreased from 38.37%to a minimum of 17.30%,the content of rapidly digestible starch in potato starch decreased from 17.82%to a minimum of 6.06%,and the content of rapidly digestible starch in pea starch decreased from 10.71%to a minimum of 3.54%.In vitro hydrolysis rate measurement,the initial hydrolysis rate of protein to starch showed a rapid upward trend,while the growth of hydrolysis rate in the later stage showed a significant slowing trend,and the digestion rate was significantly reduced.The correlation analysis results showed that the effect of the average particle size and the order of the crystal structure on the digestibility of rice starch was most significant.The effect of particle size on the digestibility of potato starch and pea starch was the most significant,while the impact of amylose overflow rate on the digestibility of the three crystalline starches was relatively small.