| Nut food is a kind of solid food with brittle characteristics.Chewing and breaking is the first step in the oral processing and a prerequisite to ensure full perception of nut texture and flavor.The particle size distribution after breaking has a direct impact on sensory experience.Therefore,breakage characteristics is an important reference factor to differentiate the eating experience of nuts.The main objective of this study is to investigate the association between the chewing fragmentation of nuts and their mastication behavior and sensory perception during oral processing.A breakage index model to quantify the breakage characteristics of nuts was established by comparing the particle breakage produced by different nut chewing and breaking,and the suitable conditions for in vitro simulated breakage were clarified.In addition,the effects of oral physiological factors and nut material factors on nut breakage index have also been investigated.Nuts with different roasting times were used to investigate the effects of different breakage indexes on individual mastication behavior,sensory perception and preference.The main research findings and conclusions are as follows:(1)The nuts were broken by both oral and in vitro fracturing tests.By comparing nut breaking characteristics obtained from three breakage index models,the most appropriate model was established.Optimum conditions for in vitro simulated oral fracture were investigated.Results show that all three breakage index models are able to quantify the fracture characteristics of nuts.However,modelⅢgives the best quantification effect.It is feasible to break nuts in vitro by changing the extent of compression deformation of texture analyzer,and the simulation effect of lower compression deformation is better.In addition,in vitro fracturing is more stable than human oral fracturing.(2)Investigate the impact of nut texture factors on breakage function by comparing the results of different nuts’breakage indexes and testing their textural characteristics.Investigate the impact of oral physiological variables on subjects’breakage capacity by comparing the results of different subjects’breakage indexes on nuts and testing their chewing efficiency,bite force,and occlusal area.The findings demonstrate a significant linear association between the hardness and brittleness of nuts and their breakage index,with higher levels of nut fracture being correlated with higher levels of nut hardness(r=0.531,p<0.01)and brittleness(r=0.315,p<0.05).The breakage index with the chewing efficiency and bite force had a strong linear relationship(r=-0.646,p<0.05;r=0.664,p<0.05);the bigger bite force and the smaller chewing efficiency,the larger breakage index.Respectively,the relationship between occlusal area and breakage index was not significant,but the occlusal area of molar teeth was rather smaller in subjects with high breakage capacity.This suggests that for nut foods,stress is more important than shear area.(3)The applicability of the breakage index model applied to the same nuts was investigated by testing the breakage index values of peanut samples with different roasting times.Mastication behavior,brittleness perception and preference of roasted peanuts were tested in 12 subjects to investigate the effect of the breakage index on the sensory experience process.Results indicate that the breakage index model III is equally applicable to the same nuts(p<0.01).In addition,the breakage index of nuts has a significant linear relationship with the subject’s chewing time and the number of chews(R~2=0.9120、0.6862;R~2=0.9491、0.8372),the larger breakage index,the less chewing time and number of chews required.The larger breakage index of the sample,the perceived brittleness intensity is stronger(R~2=0.7553),and the perceived brittleness intensity has a good agreement with the brittleness of the sample(R~2=0.6691).The higher breakage index value of the nut sample,the stronger sense of pleasure during oral processing. |
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