| In this study,Cross-Linked Octenyl Succinic Anhydride modified starch (COSA starch) was prepared with waxy rice starch, and its preparation technology ,digestion properties and some physical-chemical properties were investigated. It was in order to widen the application of modified starch,enhance its functionality ,and provide theory for practice. The research results are as follows:(1) Using Design-expert7.0 central composite design and response surface analysis method to study on the major factors:cross-linking agent dosage(A), cross-linking pH(B), cross-linking temperature(C), cross-linking time(D) and esterifying agent dosage(E)which influenced on peak viscocity(PV) and degree of substitution (DS) .The results showed that:①The regression equation ofPV is: PV =0.011- (1.459×10-4)×A- (1.309×10-4)×B-(7.681×10-5)×C- (1.063×10-4)×D- (1.242×10-4)×E+ (1.387×10-4)×A×B+ (3.237×10-4)×A×C+ (2.437×10-5)×A×D+ (2.866×10-5)×A×E+ (6.086×10-5)×B×C- (7.668×10-5)×B×D- (5.708×10-5)×B×E+ (7.015×10-6)×C×D- (6.837×10-5)×C×E- (1.997×10-4)×D×E+ (2.937×10-4)×A2+ (3.333×10-4)×B2+ (2.869×10-4)×C2+ (3.168×10-4)×D2+ (2.267×10-4)×E2.The order of major factors which influenced on the PV is: A>B>E>D>C.Through the response surface analysis,the best technologcial conditions can be obtained: cross-linking agent dosage 6.46%, cross-linking pH 9.11, cross-linking temperature 31.88℃, cross-linking time 4.44h, esterifying agent dosage5.31%.②The regression equation of DS is:DS=0.033- (2.526×10-3)×A+ (3.020×10-4)×B+ (1.455×10-3)×C- (4.942×10-4)×D+ (4.777×10-3)×E- (1.029×10-3)×A×B+ (2.326×10-3)×A×C+(4.401×10-3)×A×D+(4.208×10-4)×A×E-(4.227×10-3)×B×C+ (3.098×10-3)×B×D- (6.649×10-3)×B×E+ (2.920×10-3)×C×D-(3.177×10-3)×C×E+ (2.226×10-4)×D×E- (3.037×10-3)×A2- (1.303×10-3)×B2-(1.574×10-4)×C2- (1.680×10 -3)×D2- (1.499×10-3)×E2.The order of major factors which influenced on the DS is: E>A>OD>B.The best technologcial conditions can be obtained: cross-linking agent dosage 8.5%, cross-linking pH 10.33, cross-linking temperature 41.2℃, cross-linking time 3.37h, esterifying agent dosage5.94%.③A product with high PV and DS can be get in this technologcial condition: cross-linking agent dosage 8%, cross-linking pH 10, cross-linking temperature 37.5℃, cross-linking time 4h, esterifying agent dosage5.5%,and in this condition,PV is 8526cp,DS is 0.0305.(2) The factors which influenced on the digestion properties of COSA waxy rice starch were studied. The results showed that: cross-linking or esterification can both decrease digestibility of waxy rice starch, however, compounding these two methods was the best way to increase SDS and RS, and increased with DS increased.Dry heating can further decrease digestibility of COSA waxy rice starch, to increase the heating time or temperature properly can produce more SDS and less RS. Cold storage had little influence on the digestibility of COSA waxy rice starch,to decrease the freezing temperature or lengthen the storage time can bring a little increase of SDS.(3) The paste properties, transparency, retrogradation stability ,freeze-thaw stability and emulsifying stability were studied. The results showed that:①Compared with the unmodified starch,the PV and final viscosity of COSA starch were all increased, and gelatinization temperature,PV temperature and the appearance time were advanced, In a certain range,to increase the quality of starch can make PV increased more.②After cross-linking and esterification,the transparency of COSA waxy rice starch improved apparentely, and increased with DS increased .Add sucrose, citric acid or lactic acid can improve the transparency of COSA waxy rice starch,but salt decreased it;③Compared with the unmodified starch,the retrogradation stability and freeze-thaw stability of COSA enhanced tremendously;④The emulsification stability of COSA waxy rice starch is better than unmodified starch, and increased with DS increased. Adding sucrose can increase the emulsification stability of COSA starch, but salt decreased it. The maximum emulsification stability can be obtained when the pH is 7.
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