Effect Of Micro-nanoencapsulation On Red Raspberry Anthocyanin Stability,Characterization,Simulated Gastrointestinal Condition,and Interaction Mode

This study is about microencapsulation of red raspberry anthocyanins?AC?and their interaction mode.The properties of microcapsules prepared using different wall-materials?soy protein isolate?SPI?,gum arabic?AG?,and their combination?were studied.Ultrasonication was employed to improve the efficiency of different wall-materials and AC were encapsulated by a freeze-drying technique.The microcapsule properties,encapsulation efficiency?EE?,antioxidant capacity using the DPPH assay,Fourier-transform infrared spectroscopy?FTIR?,color stability,thermal stability,stability during storage,morphology,and AC release behavior under simulated gastrointestinal conditions were investigated.Results showed that EE ranged from 93.05%to 98.87%for all microcapsules.The morphology of microcapsules by scanning electron microscopy?SEM?indicated a broken glass shape with mean size of microcapsules ranging from 21.07±2.71?m to 48.19±2.33?m.Zeta potential?ZP?and FTIR spectrum results indicated that there was a chemical cross-link interaction between wall material and core material.All microcapsules enhanced the thermal stability of AC in the temperature range from 80 to114°C.Furthermore,AC retention?up to 48%?during storage at 37?C for 60 days revealed that treatment H?SPI+AG+0.05%AC?,the combination of SPI and AG was the best.In addition,SPI and AG combination presented good release behavior under simulated gastrointestinal conditions compared with unencapsulated anthocyanin.Through the above findings,we found that soy protein has high stability properties towards AC,so we further studied the interaction of soy protein nanogel as an advanced nano-material with AC through spectrofluorimetric studies.The interaction results showed that AC strongly quenched the fluorescence intensity of soy protein mainly through the static quenching.The number of AC binding sites per protein molecule?n?was close to 1.0.The binding constant?K_a?was 1.572*10⁴ L/M^-1 at 298 K,indicating a strong binding between AC and soy protein nanogel.The results obtained from FTIR,UV-vis,and circular dichroism?CD?confirmed that AC changed the secondary and tertiary structure of soy protein nanogel.Moreover,the band intensity of soy protein nanogel decreased with the increasing AC concentration.These results proved that encapsulation process is a good choice for increasing the stability of red raspberry anthocyanins and improving its behavior under simulated gastrointestinal.Additionally,these results may help for better understanding of the interaction between AC and soy protein nanogel and could be beneficial for the application of soy protein nanogel with AC in foods.In conclusion,microencapsulation could be considered as a useful technology to improve the stability of red raspberry anthocyanins.Moreover,the interaction between AC and wall material enhances its physiochemical properties,making it suitable for food applications.