In this study, milk fat model systems with different solid fat contents were formulated using anhydrous milk fat as an ingredient and were used separately to prepare emulsions. The oral coalescence and tribological properties of the emulsions were measured and sensory evaluation was also performed. The results showed that the milk fat model systems (F10–F85) were found to have solid fat contents of 10%–85%. The average diameter of fat globules in the emulsions (E10–E85) was about 4 µm. After simulated oral processing, the particle size of the emulsions increased, and the highest increase was observed in E40. The friction coefficient μ₂₀ of the emulsion first decreased and then increased with increasing solid fat content, and the friction coefficient μ₂₀ of emulsion E40 was the smallest (0.04 ± 0.01). The overall creaminess of the emulsion first increased and then decreased with increasing solid fat content, and the score of E40 was the highest (8.06 ± 0.73). The oral smoothness and mouth coating attributes of the emulsion were most correlated with the overall creaminess perception, and E40 had the highest correlation. At the middle and late stages of oral processing, the most dominant sensory attributes of the emulsion were oral smoothness and mouth coating. In addition, the dominance rate of oral smoothness and mouth coating of E40 were the highest. This study will provide a theoretical basis for the development of low-fat dairy products with whole milk taste.

In this work, the regulation mechanism of processed cheese stretchability was studied by adjusting the amount of added emulsifying salt (0.6%-3.0%) and potato acetate starch (0.125%-2%) and pH (5.4-5.8). The results showed that as the emulsifying salt increased from 0.6% to 3.0%, the content of bound calcium in processed cheese decreased from (4.42 ± 0.05) to (0.02 ± 0.04) g/kg, the average fat globule size D_(4,3) decreased from (73.08 ± 3.16) to (27.90 ± 2.55) μm, and the bound water content increased from (9.57 ± 0.25)% to (10.40 ± 0.25)%, indicating that the calcium crosslinking effect gradually decreased, the emulsifying effect and hydration degree increased, the interaction between protein molecules changed from strong to weak, so the stretchability of processed cheese initially increased and then decreased. As pH increased from 5.4 to 5.8, the content of bound calcium increased from (2.01 ± 0.08) to (2.74 ± 0.05) g/kg, and the average fat globule size D_(4,3) decreased from (36.36 ± 2.68) to (21.37 ± 2.39) μm. Fourier transform infrared spectroscopy showed that the bending vibration absorption peaks of O-H and N-H moved to lower wavenumbers, and the bound water content increased from (9.85 ± 0.16)% to (10.74 ± 0.12)%, indicating that the calcium crosslinking effect, emulsifying effect and hydration degree increased, the interaction between protein molecules changed from strong to weak, so the stretchability of processed cheese increased first and then decreased. As potato acetate starch concentration increased from 0.125% to 2%, the average fat globule size D_(4,3) decreased from (54.17 ± 2.74) to (29.92 ± 2.71) μm, and the bound water content increased from (9.90 ± 0.38)% to (11.00 ± 0.21)%, indicating that the emulsifying effect and hydration degree increased, and the stretchability increased first and then decreased. At a potato acetate starch concentration of 2%, starch and protein were separated, so the stretchability became worse. In conclusion, the stretchability of processed cheese is comprehensively regulated by the degree of calcium ion chelation, emulsifying effect, electrostatic interaction between protein molecules, water distribution state and protein-polysaccharide phase behavior.