Study On Construction Of Soybean Peptide-curcumin Nanoparticles And Its Microencapsulation

Soy protein hydrolysate(SPH)has a variety of excellent nutritional and physiological activities,but its unacceptable bitterness and strong hygroscopicity limit its use in foods such as beverages.It has been verified that some protein hydrolysates can form stable complexes with biologically active components through non-covalent interactions such as hydrophobic interactions.The production of bitterness may be mainly attributed to peptides having high hydrophobicity.This study utilize the hydrophobic interaction between hydrophobic polyphenol curcumin(Cur)and peptide to partially mask the exposure of the hydrophobic bitter residue of soybean peptide.To further abtain the low-taste soybean peptide microcapsules,spray-dried technology has beed attempted.The related physical and chemical properties of peptide products have been characterizated.A functional solid beverage with good flavor and stable properties has been developed.This study will broaden the APHlication of soybean peptide in the food industry.The main conclusions are as follows:(1)SPH-Cur nanoparticles were fabricated by self-assembly of soybean peptide,the colloidal properties and the debittering effects were evaluated.Soy protein hydrolysate have high hydrolysis degree and an unacceptable bitter taste which was prepared by alcalase,and its bitter taste is strongly influenced by the hydrophobic peptide content.Soybean peptide has a higher loading capacity for curcumin,which significantly reduces the bitterness of the polypeptide while significantly increasing the water solubility of curcumin.The smaller particle size and higher potential values indicate that the SPH-Cur nanoparticles have better physical stability.Fluorescence and infrared spectroscopy results show that the hydrophobic interaction between soybean peptide and curcumin can partially block the hydrophobic amino acid residues of soybean peptide,which may be an effective technology to reduce the bitterness of the peptide.(2)To prepare soybean peptide microcapsules by spray drying technique,SPH and SPH-Cur nanoparticles were used as core materials,and heat-treated soy protein(SPI)and soybean polysaccharide(SPSS)were used as complex wall materials.the properties of microencapsulated debittering effect and its product properties were evaluated.The polypeptide embedding rate of SPH microcapsules under neutral conditions(pH 7.0)was significantly higher than that of acidic conditions(pH 4.5),which was strongly influenced by the type of wall material and the ratio of core material to wall material.The core/wall ratio of the fixed microcapsules is 1/4,and the wall material ratio(SPI/SSPS)is 2:1.The microcapsules have the best embedding effect: the embedding rate is 50.92%,the bitterness is reduced by 2.68 times,and the hygroscopicity was reduced by 1.61 times.The microcapsules are spherical in shape with a smooth,continuous surface and no holes or cracks.The higher embedding rate may be mainly attributed to the core-shell bilayer structure constructed by soy protein and soybean polysaccharide complex wall material.FTIR analysis showed that electrostatic interaction occurred between SPI and SPSS.Compared with the SPH microcapsuleted product,the embedding rate of the SPH-Cur nanoparticle microencapsulated product is significantly improved and the bitterness is significantly reduced.During storage,the hygroscopicity of the two microcapsules was significantly lower than that of SPH.After reconstitution,both of them had smaller particle size and larger zeta potential,indicating that they have good physical stability.The addition of curcumin significantly increases the antioxidant activity of soy peptide microcapsules,which will enhance the competitiveness of soy peptide microcapsule products as functional ingredients.(3)A soy peptide solid beverage with good sensory and stable characteristics was prepared using microcapsules with small bitterness and low hygroscopicity as raw materials.The additions of sucrose and dietary fiber were the main factors affecting the flavor of the beverage,and the amount of maltodextrin added is a secondary factor.The best flavor sensory score formula:(1)SPH microcapsule solid beverage has sucrose,dietary fiber and maltodextrin added in an amount of 25%,35% and 3.75%,respectively;(2)SPH-Cur microcapsule solid beverage:the amount of each flavoring agent added was 25%,50%,and 3.75%,respectively.After 30 days of high temperature and high humidity storage,compared with soy peptide beverage,the DE* values of the two microencapsule solid beverages were small to medium,and no color change was observed by the naked eye,which was acceptable in the APHlication.The solid beverage is in the form of a powder,does not stick to the joint block or liquefies;and still has low hygroscopicity and high reconstitution rate(above 90%).The flavor sensory score is distributed between 80 and 100 points,showing a soft taste,no bitter taste and good storage stability.