Abstract: Mozzarella cheese is one of the most consumed and most popular cheeses with the highest import volume in China. Because it can be melted and strung when heated, Mozzarella cheese is widely used in catering industry. In this paper, the effects of hot-stretching and melting treatments on the quality characteristics of the cheese were studied, and the relationship between the change of cheese quality characteristics and the change of intermolecular interaction was elucidated. The basic composition, texture and functional properties, intermolecular interaction, glass transition temperature (Tg) and microstructure of Mozzarella cheese with different treatments (untreated, blanching, blanching and stretching, hot-stretching, melting, and melting and stretching) were determined. Compared with untreated samples, hot-stretching resulted in fat loss by 30.1% and an increase in moisture content of 15.3% The melting property of hot-stretched cheese decreased by 0.34 cm compared with untreated samples; the length of the strings of melted cheese did not change significantly, but the stringing strength increased significantly after hot-stretching treatment. After hot-stretching, the Tg value of the cheese increased by 1 ℃, suggesting that the intermolecular interaction of casein increased, and its mobility decreased. The results of hydrophobic interaction and protein solubility observed by a fluorescent probe showed that there was no significant change in hydrophobic interaction and the intermolecular hydrogen bonding force was reduced. Scanning electron microscopy showed that the three-dimensional network structure of the cheese became more compact after hot-stretching treatment, which was consistent with the change of Tg value and the determination of the solubility of the cheese.

Key words: Mozzarella cheese, hot-stretching, force, glass transition temperature, texture, functional properties