Effect of milk protein-galactomannans interaction on meltdown behavior in the aerated frozen model system

Abstract

The microstructure of ice cream and frozen desserts is known to influence their meltdown behavior. In this study, we hypothesized that the interaction of milk protein and galactomannans, specifically the phase separation often observed between hydrocolloids and protein, along with the interaction of hydrocolloids in the serum phase, affected meltdown behavior in non-fat aerated frozen foam. Ice creams were made with protein contents from 4 to 8%, with the addition of guar gum or locust bean gum. The effect of κ-carrageenan in protein and galactomannans was also studied. Melting characteristics were compared to the rheological and structural characteristics of the ice cream as well as to the phase separation in the mix and drip-through solution. The freezing-melting process inhibited microscopic and macroscopic phase separation in most locust bean gum samples, primarily due to the cryo-gel maintaining structural integrity and altering hydrocolloid-proteins interactions. The cryo-gel structure also led to slow melting rates and stable melted foams in the 4% milk protein system even in the absence of milk fat globules and clusters. Increasing milk protein from 4% to 8% in locust bean gum samples resulted in faster melting and a transition to complete dripping, indicating the disruption of the cryo-gel structure by increased proteins. In contrast, all guar gum samples fully dripped through the mesh with a fast melting rate. A negative trend was found between phase separation and melting rate in the guar gum samples containing κ-carrageenan, indicating that the diminishing interaction between the two immiscible phases accelerated liquid drainage.