| Tributyrin is an excellent butyric acid supplement,which has the physiological effect of regulating intestinal health and has a wide application prospect.However,its bitter taste,poor water solubility and low bioavailability limit its application in food field.Inclusion method can obviously improve the performance of tributyrin,and cyclodextrin is an excellent wall material.Previous studies have found that the inclusion compound with good performance could be obtained by the system of enzymic preparation of cyclodextrin inclusion tributyrin.The inclusion process promoted the formation of three types of cyclodextrins(α-,β-,γ-cyclodextrin),suggesting that there may be synergistic effect between different types of cyclodextrins.Based on this,the inclusion complexes formed byα-cyclodextrin,β-cyclodextrin,γ-cyclodextrin and complex cyclodextrins with tributyrin were characterized and identified,and the preparation system of the inclusion complexes was optimized to obtain the excellent performance of tributyrin inclusion complexes.Based on this,the inclusion complexes formed byα-cyclodextrin,β-cyclodextrin,γ-cyclodextrin and complex cyclodextrin with tributyrin were characterized and identified,and the preparation system was optimized.At the same time,the molecular mechanism of cyclodextrin inclusion tributyrin was systematically studied,the synergistic effect between different cyclodextrins was analyzed,and the application prospect of inclusion complexes in the field of food was explored.Firstly,three single cyclodextrins(α-,β-,γ-cyclodextrin)and complex cyclodextrins were used to prepare the inclusion complexes,and the inclusion complexes were characterized by fourier transform infrared spectroscopy,X-ray diffraction,particle size analysis and scanning electron microscopy.The results showed that the X-ray diffraction peaks of cyclodextrin decreased or widened after the interaction between cyclodextrin and tributyrin,and the absorption peaks of the infrared spectra of both showed different degrees of displacement and reduction,which confirmed that different cyclodextrin can form inclusion complexes with tributyrin.The size distribution of clathrate samples was roughly between1～1000μm,and there was almost no agglomeration and adhesion.The complex cyclodextrin/tributyrin inclusion complex was spherical and had a hollow structure with multiple nuclei.In order to obtain better inclusion complexes,the preparation process was optimized.Under the conditions of complex cyclodextrin ratio(α-CD:β-CD:γ-CD=20%:70%:10%,molar ratio),wall-core ratio(1:4,molar ratio),emulsifier(sucrose fatty acid ester),the inclusion effect of the inclusion compound was the best.Secondly,the product properties of complex cyclodextrin/tributyrin inclusion complexes prepared by adding different emulsifiers(monoglycine succinate,span-60,sodium stearyl lactate,sucrose fatty acid ester,span-40,octycapyl glyceride)were evaluated.After the complex cyclodextrin inclusion treatment,the odor of tributyrin was significantly reduced.The water content of clathrate was 3.66%～7.33%,and the water activity was lower than0.60(0.294～0.505),which could inhibit the growth of most microorganisms.The packing density of clathrate was high,ranging from 0.32 g/cm~3～0.55 g/cm~3.Moreover,its hygroscopic property was low(0.35%～1.49%),so it could be stored in ordinary packaging.The Zeta potential of the inclusion complexes with sucrose fatty acid ester as emulsifier was-37.80 m V,indicating that the inclusion complex had good stability.In vitro simulated release experiments showed that the tributyrin of the inclusion complexes was mainly released in the colon and rectum at the back of the large intestine,which improved its bioavailability.Thermogravimetric analysis showed that the inclusion complexes had good thermal stability below 210℃.And the accelerated storage experiment showed that the inclusion complexes could be stably stored at 20℃for 180 days.The compound cyclodextrin tributyrin inclusion complexes prepared by adding different emulsifiers had good application performance.And from the perspective of economic cost,the application effect of the clathrate prepared by sucrose fatty acid ester as emulsifier was the best.Thirdly,the molecular mechanism of cyclodextrin inclusion was explored.A single cyclodextrin could form a inclusion complex with the inclusion ratio of 1:1 with tributyrin,and the cavity size ofβ-cyclodextrin was the most suitable for the inclusion of tributyrin.Cyclodextrin inclusion of tributyrin was a spontaneous micro-exothermic process,and the inclusion of tributyrin was promoted by enthalpy and entropy synergistic drive.Entropy drive played a dominant role in the inclusion process,and hydrophobic force played a major role.The entropy change(24.3 cal/mol·K)in the process of compound cyclodextrin(α-CD:β-CD:γ-CD=20%:70%:10%,molar ratio)cladding tributyrate was increased by 36.52%compared with that of single cyclodextrin(17.8 cal/mol·K forβ-CD),and the inclusion stability constant was increased by 79.21%,indicating that the compound cyclodextrin could provide more hydrophobic cavities matching the molecular size of tributyrate,and the encapsulation capacity was stronger,so as to achieve a more stable inclusion effect.By analyzing the docking conformation of single cyclodextrin inclusion with tributyrin,the molecular model of complex cyclodextrin synergistic inclusion with tributyrin was deduced.Finally,the feasibility of application of complex cyclodextrin/tributyrin inclusion complex in food was analyzed.Application experiments in solid beverages showed that the resting angle of the solid beverage was between 30°～45°.The rehydrated emulsion was placed at room temperature for 4 h with almost no delamination and sedimentation phenomenon,and the stability was about 90%.The preparation time was about 52 s,and there was no lump and no peculiar smell after preparation.The content of tributyrate in solid beverages was 116 mg/serving(retention rate 100%).The solid drink had good fluidity,stability and punchability,and the presence of clathrate did not have a negative effect on the solid drink.Taking black tea shortbread as the addition object,compared with the food without added inclusions,it was found that there was no tributyrin odor in black tea shortbread,and there was no obvious difference in taste and texture characteristics compared with the control.The content of tributyrin in different groups of black tea shortcakes was 98mg/serving and 116 mg/serving,respectively,and the retention rate was about 98%.In summary,the results indicated that cyclodextrin/tributyrin complexes could be used as functional ingredients in solid beverages and black tea shortcakes,which had the feasibility of application in food,and could increase the nutritional value of food in maintaining intestinal health and alleviating intestinal inflammation. |
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