Study On Retrogradation Of Corn Starch At Low Temperature

Retrogradation phenomenon is commonly happened during the storage of corn starch based food or food additive of corn starch at low temperature, which has a negative effect on the quality of foods. The study on the retrogradation of corn starch has significant effect on controlling the process of starch retrogradation at low temperature, improving the quality of foods storaged at low temperature, and expanding the application of corn starch in foods.The main chemical compositions of corn starch are analyzed, such as total starch, protein, fat, phosphorus, amylose, amylopectin, etc. The effect of starch concentration and storage time on retrogradation of corn starch at low temperature is studied. The results show that the retrogradation of corn starch reach to the maximum value when corn starch concentration is40%. The retrogradation degree was also significantly increased along with the increasing of storage time, and then slightly increased after2days of storage at low temperature.The effects of food additives including trehalose, monostearin, carrageenan and beta cyclodextrin on the retrogradation of corn starch at low temperature have been studied. The results show that, all the additives have an inhibited effect on corn starch retrogradation at low temperature. The additive of trehalose with addition of1%has the best inhibited effect.The effect of beta-amylase on starch retrogradation at low temperature is investigated. By using enzyme concentration, reaction temperature and enzyme reaction time as factors, and the retrogradation degree as index, orthogonal experiments are carried out to determine the optimal process conditions of corn starch effected on the retrogradation degree. The results show that, when the beta-amylase addition is30U/g, reation time is40min, reaction temperature is55℃corn starch has the lowest retrogradation degree of18.9%.According to the investigations of X-ray diffraction, infrared spectrometer and differential scanning calorimetry, the retrogradation process of corn starch are studied at low temperature. The results show that the crystallization degree is increased during the retrogradation process of corn starch at low temperature, and also the retrogradation enthalpy and retrogradation degree are increased.Based on the analyses of differential scanning calorimetry and scanning electron microscope on the effects of trehalose and beta amylase on the retrogradation process of corn starch at low temperature, the retrogradation enthalpy and retrogradation degree of corn starch are reduced by adding trehalose and beta amylase. The starch granules are not gathered into a big lump, it is proved that the starch retrogradation can be restrained by trehalose and beta amylase. The effect of different amount of trehalose and beta amylase storage on the quality of sausage containing corn starch at low temperature are studied, by using texture analyzer, determination of water retention and sensory evaluation indicators to evaluate the sausage quality. The results showed that, by adding trehalose and beta amylase, the sausage elasticity, recovery and water holding capacity are increased, and the hardness, gumminess and chewiness are decreased. The evaluation indicators of sensory are good, and the qualities of sausage have been significantly improved at low temperature.