Preparation And Physicochemical Properties Of Lotus Seed Starch And Lotus Seed Protein Blending System

Starch and protein are important components of food.Both of them have a significant impact on the physical and chemical properties of food and food quality,expect providing rich nutrients.Studies have shown that the blending system formed between starch and protein can not only improve the physical and chemical properties of starch and protein,but also attract extensive attention for its potential applications in food,biology,medicine and other industries.In this paper,the lotus seed starch-lotus seed protein blending system was prepared by four different processes,including heat treatment,ultra-high pressure treatment（HHP）,microwave assisted treatment（MW）and high-pressure homogenization treatment（HPH）.The formation mechanism of lotus seed starch-protein blending system was clarified from the aspects of multi-scale structure（particle structure,aggregation structure,short range structure）,thermal characteristics,etc.,in order to enrich the research content of food mixing system to provide important scientific basis for expanding the application range of starch and protein.The main research conclusions are as follows:（1）Study on Structure and Thermal Properties of Lotus Seed Starch-Lotus Seed Protein Blending System Prepared by Heating TreatmentLotus seed starch and different ratios of lotus seed protein blending system（6:1,6:2,6:3,6:4,6:5,6:6）were heated（95℃,30 minutes）and the effects of lotus seed starch-lotus seed protein（LS-LP）interactions on the structure and physicochemical characteristics of the blend system were studied.The results of Fourier transform infrared spectroscopy showed characteristic peaks at 1540 cm^-1 and 3000-3600 cm^-1,indicating that electrostatic and hydrogen bonding were the main interaction forces between lotus seed starch and lotus seed protein.The UV-Vis absorption intensity（200-240 nm）of the lotus seed starch-lotus seed protein blend system increased with increasing lotus seed protein content.X-ray diffraction and scanning electron microscopy results showed that the blend system was composed of crystalline starch particles wrapped by lotus seed protein aggregates.The solubility,swelling properties,and thermal properties of the blend system indicated that the increasing lotus seed protein content limited the Swelling power of the lotus seed starch particles.The study of pasting properties showed that the formation of the lotus seed starch-lotus seed protein blend system improved its structure and storage stability.（2）Study on the Structure and Thermal Properties of Lotus Seed Starch-Lotus Seed Protein Blending System Prepared by HHP TreatmentBased on the formulation of the lotus seed starch-lotus seed protein blend obtained in Chapter 1 by heat treatment（LS/LP=6:3）,lotus seed starch-lotus seed protein blending system were prepared by different ultra-high pressure treatments（100-600 MPa,10-60 min）,and the effect of ultra-high pressure on the structure and physicochemical properties of the lotus seed starch-lotus seed protein blending system was studied.The results of Fourier transform infrared spectroscopy showed that three characteristic peaks of the lotus seed starch-lotus seed protein blending system changed after ultra-high pressure treatment,reflecting the change in the hydrogen bond content in the blend.The UV-visible absorption spectra showed that the blend treated with 400 MPa for 60 min had the strongest UV absorption intensity（200-240 nm）and the highest degree of combination.The lotus seed starch-lotus seed protein blending system maintained a type C crystal structure under ultra-high pressure,but the crystallinity decreased with the increase of pressure.Scanning electron microscopy showed that lotus seed starch and lotus seed protein existed in a blended form.Ultra-high pressure treatment improved the hydrophilicity of the blending system,leading to an increase in viscosity,disintegration value,regeneration value,solubility,and Swelling power,but a decrease in the gelatinization peak temperature and enthalpy value.Compared with heat treatment,ultra-high pressure treatment can maintain the apparent morphology and crystal structure of the blend to the greatest extent while improving the physicochemical properties of the lotus seed starch-lotus seed protein blend.（3）Study on the structure and thermal properties of lotus seed starch-protein Blending System prepared by MW treatmentStructural and physicochemical properties of lotus seed starch-lotus seed protein blending system prepared by microwave treatment were studied based on the complex ratio obtained through thermal treatment in Chapter 1.Lotus seed starch-lotus seed protein blending system were prepared under different microwave treatment intensities（200-400 W,4-20 min）to investigate the effect of microwave treatment on the structure and physicochemical properties of the blending system.Fourier transform infrared spectroscopic studies show that the interaction forces between lotus seed starch and lotus seed protein after microwave treatment are electrostatic interaction and hydrogen bonding.Under different microwave treatment intensities,the structure of the lotus seed starch-lotus seed protein blending system was disrupted,and the UV absorption intensity（200-240 nm）decreased.Scanning electron microscopy showed that lotus seed starch and lotus seed protein existed in a compatible form.High microwave power and long time can inhibit the formation of crystal structure in lotus seed starch,and the crystallinity decreases significantly.Microwave treatment causes violent vibrations in the molecules of the blending system.The increase in microwave power and time destroys the molecular structure of the blending system,leading to a decrease in enthalpy,gelatinization temperature,and solubility,but an increase in viscosity,disintegration value,and solubility.In conclusion,the best process for preparing lotus seed starch-lotus seed protein blending system with more complete crystal structure and better stability using microwave treatment was 280 W for 8 minutes.Compared with heat treatment,the lotus seed starch-lotus seed protein blending system prepared by microwave treatment have higher system viscosity.（4）Study on Structure and Thermal Properties of Lotus Seed Starch-Protein Bleding system Prepared by HPH treatmentBased on the composite ratio obtained from the heat treatment in Chapter 1,the lotus seed starch-lotus seed protein blending system were prepared under different high pressure homogenization intensities（20-60 MPa,2-6 min）to investigate the effect of high pressure homogenization treatment on the structure and physicochemical properties of the blending system.The Fourier transform infrared spectroscopy results showed that the changes in the related characteristic peaks reflected the existence of electrostatic interaction and hydrogen bonding between Lotus Seed Starch and Lotus Seed Protein.The lotus seed starch-lotus seed protein blending system had the highest ultraviolet absorption intensity（200-240 nm）under the conditions of 60 MPa for 2 min.Scanning electron microscopy showed that blends with different high pressure homogenization intensities exhibited various blend forms.The crystalline structure of the blending system showed a C-type crystalline structure after treating,but the crystallinity decreased.The viscosity,enthalpy value,swelling power degree,and solubility of the lotus seed starch-lotus seed protein blending system were positively correlated with the treated pressure,but negatively correlated with the homogenization time.Compared with ultra-high pressure treatment,high-pressure homogenization treatment could prepare blending system with higher viscosity,better thermal stability,and anti-aging ability,and the optimal preparation process was 60 MPa for 2 min.