Effect Of Oxidized Potato Starch On Gelatin Gel Formation

Recent years,as a pillar snack industry,great changes have taken place in the gradually mature candy industry in China whose market prospect can not be underestimated.Gelatin candy has been very popular in jelly candy because of its unique texture and taste.Mixed candy of starch and gelatin gradually replaced pure gelatin candy to overcome the problem that the texture of simple gelatin candy is hard to chew and it is difficult to store.At present,improving the quality of gelatin by adding varied starches becomes a hotspot,and after a series of studies,researchers find that oxidized potato starch can significantly improve the quality of gelatin and is the best candidate among various starches.Previous studies have focused on the microstructure and rheological properties of mixed gel,but there were few studies on the mechanism of the mixed system of oxidized potato starch and gelatin.Therefore,to study the effect of oxidized potato starch on gelatin's physicochemical properties,we established mixed gel system composed of gelatin and oxidized potato starch.And we further explored the the mechanism how oxidized potato starch and gelatin interact with each other so as to provide theoretical basis for improving the quality of gelatin candy.The main contents of this paper include the following aspects:(1)The establishment of mixed gel system.Based on the formula and preparation method of gelatin candy,the mixed gel system formed by gelatin and oxidized potato starch,water and citric acid and the ratio of the three was 1:9:0.4.The gelatin was gradually substituted by oxidized potato starch until the ratio was 5:5.(2)Effect of oxidized potato starch on physicochemical properties of gelatin gel system.The macroscopic phase separation,texture properties(hardness,springiness,chewiness,cohesiveness),microstructure(SEM)and thermodynamic temperature curve(by DSC)of the samples were analyzed by changing the ratio of oxidized potato starch and gelatin.The results showed that the phase separation was obvious when the ratio of gelatin and oxidized potato starch was 9:1 and 8:2.The phase interface disappeared when the mixing ratio is 7:3 and the whole system was clear.The oxidized potato starch could significantly enhance the hardness and chewiness of the under phase gel when the ratio was 9:1,and the parameters of hardness and chewiness decreased when increasing the proportion of oxidized potato starch.The microstructures of the surface and cross section of the gel were observed by scanning electron microscopy(SEM).Then we found that there existed empty pores and network structures in the surface of the mixed gel and the starch was embedded in the continuous phase of gelatin.When the ratio of oxidized potato starch gradually increased,the surface of the network structure,empty pores and the internal mosaic structure disappeared,finally the system achieved transparent.The melting temperature(T_m)and isomerization temperature(T_i)of the mixed gel were higher than control groups which were formed by pure gelatin and pure oxidized potato starch,indicating oxidized potato starch could improve the thermal stability of the mixed gel system.(3)To explore the mechanism of gelatin and oxidized potato starch in mixed gel system.Zeta potential and Fourier transform infrared spectroscopy(FTIR)were determined.The results showed that the Zeta potential decreased with the increase of the ratio of oxidized potato starch,indicating that there was electrostatic interaction in the system.By analyzing FTIR of different sample groups,we found there existed intermolecular hydrogen bonds and electrostatic interaction in the complex system of gelatin and oxidized potato starch.