关键词: 再制干酪, 拉伸性, 钙分布, 水分分布, 乳化性

Abstract: Processed cheese is a type of cheese product processed with natural cheese as the main raw material,which has the advantages of uniform texture, soft taste, long shelf life and portability, and is favored by consumers. Stretchability is an important functional property of processed cheese products, which has a significant impact on the quality of products. However, at present, the regulation mechanism of the stretchability of processed cheese is not clear, which limits the consumption of processed cheese. In this experiment, the regulation mechanism of the stretchability of processed cheese was studied by regulating addition of emulsifying salt (0.6% - 3.0%), pH value (5.4-5.8) and addition of potato acetate starch (0.125% - 2%). The results showed that when the emulsifying salt increased from 0.6% to 3.0%, the content of bound calcium in processed cheese decreased from 4.42 ± 0.05 g/kg to 0.02 ± 0.04 g/kg, and the average fat globule size D[4, 3] decreased from 73.08 ± 3.16 μm to 27.90 ± 2.55 μm ,the bound water content increased from 9.57 ± 0.25% to 10.40 ± 0.25%, indicating that the calcium crosslinking effect gradually weakened, the emulsifying effect of cheese increased, and the hydration degree of cheese increased, resulting the stretchability increased first and then decreased.; When the pH value increased from 5.4 to 5.8, the content of bound calcium in processed cheese increased from 2.01 ± 0.08 g/kg to 2.74 ± 0.05 g/kg, and the average fat globule size D[4, 3] decreased from 36.36 ± 2.68 μm 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 low 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, resulting the stretchability increased first and then decreased; When potato acetate starch increased from 0.125% to 2%, the average fat globule size D[4, 3] decreased from 54.17 ± 2.74 μm to 29.92 ± 2.71 μm. The bound water content increased from 9.90 ± 0.38% to 11.00 ± 0.21%, indicating that the emulsifying effect and hydration degree of cheese increased, and the stretchability increased first and then decreased. When the addition of potato acetate starch reached 2%, the starch and protein separated, and 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

Key words: Processed cheese, stretchability, calcium distribution, moisture distribution, emulsibility