The Study On Structure And Properties Of Canistel (Lucuma Nervosa A.DC) Starch And Complex With Quercetin

Canistel（Lucuma nervosa A.DC）is a perennial fruit of the genus Laminaceae,which is widely distributed in tropical and subtropical regions.Canistel is rich in nutrients and has high carbohydrate content,which can help digestion,promote blood circulation and strengthen body,dissolve phlegm,reduce pressure and reduce fat,and refresh one’s mind.At present,domestic and foreign research on canistel mainly focuses on variety selection,planting and cultivation,nutrient composition,pigment extraction,biological characteristics and molecular biology,while canistel starch and application research are rarely involved.This paper mainly focused on canistel,using scanning electron microscopy,particle size analyzer,X-ray diffraction,FTIR and ¹³C CP/MAS NMR,etc.to study the effects of different drying methods,different parts and ultrasonic and quercetin on the structure of canistel starch.Differential calorimeter scanning,rheometer and in vitro digestion were used to determine the effects of different drying methods,different parts and ultrasonic and quercetin on the physicochemical properties of canistel starch,so as to provide theoretical basis for the application of quercetin to starch quality improvement.The main research contents and results are as follows:1.The effects of hot air drying,freeze drying and vacuum drying pretreatment on the structural characteristics and physicochemical properties of canistel flesh starch showed that,compared with hot air drying,the canistel flesh starch after different drying pretreatments had a typical A-type crystal structure;the freezing drying pretreatment treatment can reduce the migration of bound water and had the smallest volume average particle size,but freeze drying destroyed the ordered structure of starch granules;the vacuum drying pretreatment can appear cracks on the surface and promote the formation of double helix structure on the surface of starch granules.These structural changed to affect the physicochemical properties of starch granules.The starch structure and physicochemical properties of canistel pretreated by different drying methods are different,but the difference was small.Combined with practical operation and cost factors,hot air drying pretreatment was determined as the most suitable drying method for the canistel.2.The results of measuring the structure and physicochemical properties of canistel starch obtained by hot air drying showed that the amylose content in the canistel flesh starch and seed starch accounted for 28.86%and 41.26%of the total starch.Most of them were bell-shaped and round and the surface of the particles was flat and smooth;the particle size distribution was wide and showed a three-peak distribution,the volume average diameters of the canistel flesh and seed starch were 80.94μm and 116.37μm,respectively;the canistel flesh and seed starch had a typical A-type crystal structure,with the crystallinity of 11%and 17%,respectively;the double helix structure of seed starch was higher than that of flesh starch;the weight average molecular masses were 683 204g/mol（flesh starch）and 753 159 g/mol（seed starch）,respectively,and the composition was more complex;the digestibility of flesh starch was higher than that of fruit seed starch.3.The effects of ultrasonic treatment at different temperatures on the structure and physicochemical properties of the canistel seed starch-quercetin complex were investigated.The results showed that the size of gelatinized starch granules increased with the increase of temperature by ultrasound,but the addition of quercetin could protect the size of starch granules by ultrasound;X-ray diffraction and infrared spectroscopy indicate that quercetin binds to the surface of fruit seed starch through hydrogen bonds.The compound and native starch had the same crystal structure and increased crystallinity.In terms of physical and chemical properties,the solubility and swelling power of the complex increase significantly after the combination of starch and quercetin after ultrasonic treatment,and the apparent viscosity increases,but the thermal stability decreases and the digestibility decreases.In addition,at 80℃ultrasonic treatment canistel seed starch and quercetin compound,the compound showed the smallest starch particle size,the lowest order degree,the largest crystallinity,the highest solubility and expansion force,the lowest stability,yield stress,viscosity coefficient and digestibility.