Research On Small Molecular Aroma Component Included By The Enzymatic Hydrolysis Of Indica Rice Starch

In order to improve the inclusion ratio of indica rice starch complexing aromacompounds,the method of moderately enzymatic hydrolyzing by isoamylase was applied,and the parameters of enzymatic hydrolysis were optimized by single factor and orthogonal test.The wall materials obtained were used to complex linalool,heptanol and menthol individually.The morphological characteristics,molecular structure,thermodynamic characteristics and release characteristics of three inclusion complex were measured and analyzed,the main results were as follws:1.With the inclusion ratio as index,the optimum preparation parameters of each kind of wall material of different aroma compounds were determined by single and orthogonal test.The optimal preparation parameters of linalool-wall material were enzymatic hydrolysis time 20min,substrate concentration 0.04g/mL,enzyme concentration 30mg/g;the optimal preparation parameters of heptanol-wall material were enzymatic hydrolysis time20min,substrate concentration 0.03g/mL,enzyme concentration 30mg/g;the optimal preparation parameters of menthol-wall material were enzymatic hydrolysis time30min,substrate concentration 0.05g/mL,enzyme concentration 30mg/g,three aroma inclusion complexes reached the optimal inclusion by linalool-complex 79.50%,heptanol complex 75.50%,menthol-complex 87.38%.The inclusion ration of indiaca rice starch-arma compounds were determined as a contrast:linalool complex59.9%,heptanol-complex55.7%and menthol-complex 58.3%.2.The properties of the prepared wall materials were characterized by amyose content,DE value,solubility and swelling degree.The amylase content of linalool-wall material,heptanol-wall material and menthol-wall material were increased by 14.91%,17.42%and21.56%on the basis of indica rice starch.The DE value of linalool-wall material,heptanol-wall material and menthol-wall material were 14.32,15.06 and 19.37 respectively.The solubility of linalool-wall material,heptanol-wall material and menthol-wall material were16.75%,18.16%and 26%respectively.The swelling degree of linalool-wall material,heptanol-wall material and menthol-wall material were 11.12%,11.09%and 12.26%respectively.3.Three kinds of aroma complexes were characterized of aspects of morphology,thermodynamics and molecular structure.The analysis results were as follows:（1）Scanning electron microscopy（SEM）results showed us a glass-like structure,amorphous and shrinkage-free,something like this amorphous glassy states,both wall material and inclusion complexes,the surface of three inclusion complexes appeared many hollow structure on the basis of wall materials.（2）Theromogravimetric analysis（TGA）results showed that the weight loss rate of linalool-wall material,heptanol-wall material,and menthol-material were 16.17%,21.53%and 18.37%,were lower than those of their corresponding inclusion complexes as 20.62%,23.50%and 23.63%respectively,and the start temperature and peak temperature of wall materials were higher than their corresponding inclusion complexes.（3）Fourier transform infrared spectroscopy（FT-IR）results showed that the vibration absorption peak of C=C of the linalool was observed at1653 cm^-1 in the spectra of linalool-complex.The absorption peak of C-H bending vibration of heptanol was observed at 1370.03 cm^-1 in the spectra of heptanol-complex.The three kinds of inclusion complexes had the mifration of C-O absorption peak compared with corresponding wall materials.No new chemical bond was formed.（4）C-NMR spectra（CP/MAS 13C-NMR）results showed that C2-C4 chemical shift of linalool were observed at 104.36ppm,144.17ppm,130.9ppm,122.18ppm,114.30ppm,111.56ppm,107.95ppm and 103.53ppm in the spectra of linalool-complex spectra.No obvious special chemical shift of other flavor compounds were observed in their corresponding complexes spectra,but there were still many differences among wall materials and their inclusion complexes.（5）X-ray diffraction analysis results showed that all wall materials and inclusion complexes were completely amorphous structure,no new crystallined structure was formed.4.Release kinetics test of three inclusion complexes showed that the release rate increased with the temperature and relative humidity.The release rate constant k and the release mechanism constant n were obtained through Avrami equation.The k value showed that the storage stability of menthol-complex was higher than linalool-complex and menthol-complex.The n value was ranged between 0.36-0.74.indicating the flavor compounds were controlled release in the protection of wall material.