The ingredient formulas, production processes and requirements for soft ice cream and hard ice cream are different. Soft ice cream has no solidification process in the production process and uses vacuum puffing, with an expansion rate of 30-60%. It requires higher production equipment, and the price of its production equipment is higher than that of hard ice cream production equipment. Generally made and sold immediately, the paste is extremely smooth, fluffy, nutritious, fresh and soft in taste, mellow and refreshing, and is a favorite ice cream variety for the elderly and children. Hard ice cream is expanded by refrigerated air, with an expansion rate of 80-100%. It has more ingredients and the price of raw materials is slightly higher than that of soft ice cream. It has a dense, sweet taste and a long aftertaste. Physical properties of ice cream: Ice cream is a frozen dairy product. The change in its physical structure is a complex physical and chemical process. Air bubbles are dispersed in a continuous liquid state with ice crystals. This liquid state contains fat particles, milk protein, Insoluble salts, lactose crystals, colloidal stabilizers and sucrose, lactose, soluble salts, such a three-phase system consisting of gas phase, liquid phase and solid phase can be regarded as a partially frozen foam containing 40%-50% volume of air. . The quality standards of ice cream can be found in the national industry standard SB/T10013-99. To meet the prescribed ice cream quality standards and physical structure, the composition of the ice cream mix (formula and quality of raw and auxiliary materials), production process conditions and production equipment should be analyzed and studied.