Modulating fat crystallization behavior in ice cream with mono- and diglycerides: Influence on microstructure and shrinkage

Abstract

Ice cream commonly experiences volume shrinkage, especially during storage and transportation with temperature fluctuations. The 3D semi-crystalline fat network supports the spatial structure of ice cream, preventing the coarsening of elements like foams and ice crystals during temperature fluctuations, ultimately reducing volume shrinkage. This study investigates the impact of fat crystallization behavior on the formation of the fat network, examining the correlation between ice cream shrinkage and fat crystallization induced by mono- and diglycerides. Techniques include differential scanning calorimetry, polarization microscopy, contact angle measurement and oscillatory thermorheometry. Shape retention is assessed through melting and freeze-thaw tests, and ice cream microstructure is observed using microscopy. Results shown mono- and diglycerides significantly impacted fat crystal wettability and emulsified fat crystallization kinetics, altering the ice cream microstructure, and contributing to heat shock-induced shrinkage. Saturated monoglyceride formed a two-dimensional crystalline layer at fat globule interface, causing fat network absence and significant shrinkage. Slightly unsaturated monoglycerides increased nucleation dimensions (n from 2.22 to 2.71), forming large fat aggregates (around 39 μm), supporting a rigid network, and reducing the shrinkage rate (from 36% to 23%). Highly unsaturated monoglycerides increased crystal growth rate (kz from 0.72 to 0.84), elevating solid fat content, and creating protrusions that damaged air bubbles, leading to a 45% shrinkage rate. Additionally, saturated emulsifiers with diglycerides reduced crystal growth rates, increased fat crystal nucleation dimensions, and hydrophobicity (kz from 0.72 to 0.63 and n from 2.22 to 3.12), forming smaller fat aggregates (around 7 μm) and minimizing shrinkage to 6%.