Effects of the degree of oral processing on the properties of saliva-participating emulsions:using stewed pork with brown sauce as the model

This work investigated the changes in properties of saliva-participating emulsions during different oral processing stages(the whole process from intake to swallowing was divided into five stages,i.e.,20%,40%,60%,80%and 100%stage).The stewed pork with brown sauce was masticated and the emulsion was collected for the determination of emulsion stability,droplet size,ζ-potential,interfacial tension,and microstructure.The results showed that the emulsion stability increased gradually during the oral processing and reached the highest level near the swallowing point.The droplet size of emulsion showed a significant downward trend(P<0.05).Microstructure observations also found different degrees of reduction in fat droplets size at different stages of oral processing.In addition,theζ-potential of food boluses emulsion was decreased from-16.4 mV to-41.2 mV and the interfacial tension decreased by 52.6%before and after oral progressing.In conclusion,the oral processing of stewed pork with brown sauce was essentially a process in which fat was constantly emulsified,and saliva might act as an emulsifier.This study provides new insights on understanding the oral processing process and sensory changes of fat.