Enzymatic Preparation Of Fatty Acid Esters Of Starch And Application Of Emulsified Essence

Starch is an abundant natural macromolecular material that is cheap, fully biodegradable and reproducible. The application of starch involved in food, medicine, cosmetics, textile and other fields. The further application of starch is limited, because of crystalline structure of starch molecules. To obtain starch derivatives have different properties by modifying starch molecules, more excellent properties of starch can be got and the application field is expanded. One of the starch modification methods is esterification. The special properties of esterification modified starch as hydrophobic, thermoplastic, emulsification, biodegradable, can be used to replace a variety of petrochemical products. The study of the esterification modified starch has a profound theoretical and practical significance.Native corn starch (NCS) was pretreated with NaOH/urea/H2O solution at cool temperature, using PCS as raw material and fatty acid as esterification reagents, in order to synthesis starch eater by enzymatic method under solvent-free conditions. On the basis of enzymatic synthesis, control water activity by rotary evaporation. With the degree of substitution (DS) as an evaluating parameter, the effect of some factors on the substitution degree was studied under the single factor experiment conditions, which include the time of initial oil bath, the time of rotary evaporation, the content of molecular sieve, and the revolution of rotary evaporation. According to these results, the perpendicular experiments are designed. The most optimal process condition of oleate starch ester is as follows:the time of initial oil bath is5h, the time of rotary evaporation is8h, the content of molecular sieve is7/g, the revolution of rotary evaporation is200r/min. Obtain the DS of octylic acid starch ester is2.437X10-3:the DS of lauric acid starch ester is2.412×10-3:the DS of stearic acid starch ester is2.364X10"3; the DS of oleate corn starch ester of2.352×10-3under above conditions.The structure of four kinds of fatty acid starch ester is studied with modern instruments. SEM images show that the granular morphology of PCS is changed, being similar with starch ester. Infra-red spectrometris show that the intensity of characteristic absorption peak of hydroxyl in PCS increases and the characteristic absorption peak of ester bone appears. X-ray diffraction diagram show that the crystalline structure of NCS is damaged, the crystal shape of PCS change, being similar with starch ester. This phenomenon reveal that the esterification reaction mainly occur in the amorphous region of starch molecules.Comparing the properties of four kinds of fatty acid starch ester, the change of pr operties of different length of chain fatty acid ester starch is investigated. The chain len-gth and satruation of fatty acid may have effect on the parameters of reaction kinetic and the a-ctivity of enzyme catalytic, and the properties of production. Compared to nature corn starch dose the solubility of fatty acid starch ester increase. The transparency of starch paste decreased. The starch paste is shear thinning, belonging to Pseudoplastic Liquid. The anticoagulant of starch paste increases and the stability of freeze-thaw increases. Starch ester gets the ability of emulsification with high emulsification and emulsion stability.Taking oleic acid starch ester as emulsifier to emulsify banana flavor, the optimal process conditions for emulsion:the content of oleate starch ester is18%, the content of banana flavor is5%, homogenating temperature is15℃, the time of ultrasonic is4min. By obserbation of emulsified flavor that diluted1000times, it can be found that the banana emulsified flavor do not deposit within24h.