| In recent years,it has been a hot research topic to regulate the sensory and functional properties of food using interaction between food components in food science.Starch is an indispensable food nutrient,and its interaction with phenolic compounds is gradually becoming the focus.The non-covalent binding of starch and polyphenol is one of the most basic factors affecting the quality of polyphenol-rich foods.Hydrogen bonds combination and hydrophobic interaction between starch and polyphenol may result a significant decrease in the digestibility of starch,and caused changes in its gelatinization,retrogradation and rheological properties by varying degrees.In this paper,lotus seed starch-green tea polyphenol complexes were prepared by ultrasound-microwave synergistic interaction,high-pressure homogenization and high hydrostatic pressure.And multi-scale structure(particle structure,aggregation structure and short-range structure),thermal and digestion properties of lotus seed starch-tea polyphenol complex were investigated to clarify their formation mechanism and anti-digestion characteristics.The main results are as follows:(1)The structure and digestion properties of the lotus seed starch-green tea polyphenol complexes(LS-GTP)under conduction heating(CH)LS-GTP was prepared via CH and its particle structure,aggregationstructure,thermal and digestion properties were investigated.The results showed that the non-covalent interaction between lotus seed starch and tea polyphenols was induced by CH,which resulted in the changes of their physicochemical properties.The results of swelling power and solubility,scanning electron microscopy(SEM)and particle size measurement showed that the swelling power of lotus seed starch decreased and the solubility increased after conduction heating,and the starch particles twisted and ruptured with a rough surface.By means of x-ray diffraction(XRD)and confocal laser scanning microscopy(CLSM),it was found that lotus seed starch and tea polyphenol formed a V-type inclusion complex after CH,with a part of tea polyphenol attached to the starch surface,and the rest embedded in the starch cluster.The results of differential scanning calorimetry(DSC)show that the gelatinization temperature values(To,Tp,Tc)and gelatinization enthalpy(△H)of LS-GTP were obviously decreased and its thermal stability is poor.Dynamic in vitro rat stomach-duodenum(DIVRSD)model was used to simulate the digestion process of LS-GTP.The results showed that the glucose concentration of LS-GTP after digestion of 180 min was about14%,which lower than that of the control,suggesting that the complex was anti-digestion.(2)The structure and digestion properties of the lotus seed starch-green tea polyphenol complexes(LS-GTP)under ultrasound-microwavesynergistic interaction(UM)LS-GTP was prepared via UM.The particle structure,aggregation structure and viscosity characteristics of LS-GTP under microwave or ultrasound alone were investigated.At the same time,the multi-scale structure and digestion characteristics of LS-GTP prepared by UM were studied.The results showed that the morphology of starch particles was twisted with fragments appeared on the surface,and the crystalline structure of starch changed from C-type to V-type after microwave treatment,while it remained C-type after ultrasonic treatment.And the viscosity values(To,Tp,Tc)of lotus seed starch treated by microwave or ultrasonic treatment were lower than that of control,indicating that microwave and ultrasonic treatment could destroy the crystalline region of lotus seed starch.UM treatment induced non-covalent interaction between lotus seed starch and tea polyphenols and formed LS-GTP,which resulted in changes of their physicochemical properties.Fourier transform infrared spectroscopy(FTIR)suggested a decrease in the molecular ordering of LS-GTP.By means of XRD,composite degree analysis,SEM and CLSM,it was found that,LS-GTP exhibited a C-type crystalline structure and tea polyphenols attached on the surface of starch granules at 200 W ultrasound,called non-inclusive complex.While ultrasonic power reaches 400 W,the crystalline structure changes from C-type to V-type,and tea polyphenols are embedded in the inner part ofstarch cluster to form a V-type complex.The results of swelling power and solubility,and particle size measurement showed that the swelling power of LS-GTP decreased and the solubility increased,and the particle size increased first and then decreased with the change of ultrasonic power.DIVRSD model was used to simulate the digestion process of LS-GTP.The results showed that the digestion efficiency decreases gradually with the increase of ultrasonic power,suggesting that the complex was anti-digestion.(3)The structure and digestion properties of the lotus seed starch-green tea polyphenol complexes(LS-GTP)under high-pressure homogenization(HPH)LS-GTP was prepared via HPH and its multi-scale structure and digestion characteristics were investigated.The results show that HPH treatment induced non-covalent interaction between lotus seed starch and tea polyphenols and formed LS-GTP,which resulted in changes of their physicochemical properties.The results of swelling power and solubility,and particle size measurement showed that,the particle size and swelling power of LS-GTP decreased with the increase of pressure and times,while the solubility increased.By means of XRD,composite degree analysis,SEM and CLSM,it was found that LS-GTP exhibited a C-type crystalline structure,with a higher content of tea polyphenol attached to the surface of starch granules,called non-inclusive complex.While thecrystalline structure changed from C-type to V-type with enhance of HPH,formed V-type inclusion complex,with the content of tea polyphenols decreased and embedded in the inner part of starch cluster.DSC study suggested that the crystalline region of starch was destroyed and a new crystalline structure was formed.DIVRSD model was used to simulate the digestion process of LS-GTP.The results showed that the glucose concentration of LS-GTP after digestion was decreased with the increase of treatment pressure and passes.(4)The structure and digestion properties of the lotus seed starch-green tea polyphenol complexes(LS-GTP)under high hydrostatic pressure(HHP)LS-GTP was prepared via HHP and its multi-scale structure and digestion characteristics were investigated.The results show that HHP treatment induced non-covalent interaction between lotus seed starch and tea polyphenols and formed LS-GTP,which resulted in changes of their physicochemical properties.The results of swelling power and solubility,and particle size measurement showed that,the particle size of LS-GTP increases obviously,the swelling power decreases and the solubility increases with the increase of treatment pressure and passes.By means of XRD,composite degree analysis,SEM and CLSM,it was found that,the crystallinity of C-type LS-GTP crystalline structure decreases,and starch granules were gelatinized gradually with the increase of pressure andpasses,and the content of GTPs in the system decreased and attached to the surface of starch particles to react with them to form non-inclusive complexes.DSC suggested that the crystalline region of starch was destroyed and thermal stability of LS-GTP is poor.DIVRSD model was used to simulate the digestion process of LS-GTP.The results showed that the complex was anti-digestion. |
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