Improving productivity of starch nanocrystals (SNC) using sonication and characteristics of SNC-stabilized Pickering emulsions

학위논문 (석사)-- 서울대학교 대학원 : 농생명공학부, 2017. 2. 최영진.Pickering emulsions are an emulsion stabilized with solid particles instead of using chemical emulsifier. It has excellent storage stability compared to traditional emulsion. Recently, studies for stabilizing emulsions using food-grade particles such as protein and starch have been actively carried out. However, application of the emulsions to actual foods is restricted to ice cream, foam, and whipping cream because the size of the emulsions is too large to maintain the dispersed state. In this study, Pickering emulsion with nanoscale particle size and colloidal stability was developed using starch nanocrystals of 20-50 nm level. After acid hydrolysis, starch nanocrystals were separated by centrifugation, and microparticles were treated with ultra-sonication until the temperature at which starch nanocrystals were gelatinized to further separate starch nanocrystals, which were incompletely hydrolyzed during acid hydrolysis, the yield was improved. To increase the hydrophobicity of hydrophilic starch nanocrystals, OSA-modified starch nanocrystals were prepared by esterification of starch nanocrystals with octenyl succinic anhydride (OSA). Gellan gum and polydimethyl siloxane (PDMS) were used to confirm the dual wettability of OSA-modified starch nanocrystals to both aqueous phase and oil phase. Ultra-sonic treatment of OSA-modified starch nanocrystals-stabilized Pickering emulsions reduced the emulsion particle size and increased the emulsion efficiency of OSA-modified starch nanocrystals. Then, Pickering emulsions which has excellent colloidal stability and storage stability was developed by varying the concentration of OSA-modified starch nanocrystals. The Pickering emulsions developed in this study can be used as a basis for research on the development of food and drug carriers by adding colloidal stability to existing Pickering emulsions.I. Introduction 1 II. Materials and Methods 8 2.1. Chemicals and reagents 8 2.2. Starch nanocrystals (SNC) preparation 8 2.3. OSA Modifications 10 2.4. Determination of degree of substitution (DS) 10 2.5. Dual wettability of SNC at oil-water interfaces measurement 11 2.6. Simple emulsification activity test 13 2.7. O-SNC-stabilized Pickering emulsion preparation 13 2.8. Powder X-ray diffraction (XRD) analysis 14 2.9. Differential scanning calorimetry (DSC) 14 2.10. Scanning electron microscopy (SEM) 15 2.11. Light transmittance (%) 15 2.12. Particle size measurements 16 2.12.1. Dynamic light scattering (DLS) 16 2.12.2. Laser diffraction (LD) 16 2.13. Optical microscopy 17 2.14. Transmission electron microscopy (TEM) 17 2.15. Statistical analysis 18 III. Results and Discussion 19 3.1. Starch nanocrystals (SNC) preparation 19 3.2. Simple emulsification test 26 3.3. Improving the productivity of SNC 28 3.4. OSA-modification of SNC 36 3.5. Partial wettability of O-SNC to both aqueous phase and oil phase 38 3.6. O-SNC-stabilized Pickering emulsions 41 3.7. Morphologies of O-SNC-stabilized Pickering emulsions 49 IV. Conclusions 52 V. References 54 VI. 국문초록 60Maste