Effect of hydrolysis of lactose and sucrose on firmness of ice cream

Abstract

Ice cream mixes were treated enzymatically with combinations of lactase (EC 3.1.1.12) and invertase (EC 3.2.1.26) to cause 0–78% hydrolysis of lactose and 0–50% hydrolysis of sucrose. While the action of the invertase was limited principally to sucrose, the lactase enzyme caused hydrolysis of both lactose and sucrose. Relative firmness (hardness) of the ice cream was measured in the temperature range of −15 to −18°C and was assessed by the work expended by penetrating the frozen ice cream to a depth of 10 mm with a cylindrical probe of diameter 7 mm, travelling at 20 mm/min. Hydrolysis of lactose and sucrose increased the sweetness but decreased the freezing point of the mix and the firmness of the finished product. Within the hydrolysis range achieved (0–59.3% of the total saccharides), organoleptic properties and melt-down characteristics were not significantly impaired.