The quality indicators of ice cream upon the enzymatic hydrolysis of lactose

Abstract

Ice cream is a popular type of dairy foods containing up to 6% of lactose. In connection with the lactose intolerance by many consumers and the possibility of its crystallization during storage of finished products, there is a need for a decrease in the content of this nutrient in the composition of ice cream. The aim of the research was to study an effect of the lactose hydrolysis process in ice cream with the fat mass fraction of 15% and different mass fractions of dry skim milk residue on technologically significant and sensory properties of its quality. The main objects of the study were samples of ice cream subjected to lactose hydrolysis at the stage of mixture maturation. The fat mass fraction in the samples was 15%, mass fractions of dry skim milk residue were 7, 10, 12 and 15%. The composition of sugars was determined by high-performance liquid chromatography, the dynamic viscosity of mixes and the consistency of ice cream by rheological methods and the dispersion of structural elements by microcopy. The effects of the mass fraction of dry skim milk residue and lactose hydrolysis on quality indicators of mixtures and ice cream were determined. As the mass fraction of dry skim milk residue rose from 7 to 15%, the residual content of lactose increased from 0.2 to 1.1%, while the dynamic viscosity of the mixture increased by 1.3 times. A decrease in the freezing point by 0.6–0.8 °C and an increase in melting resistance were also observed. The mass fraction of melt after 2 hours of holding decreased to 4.7–0.7%. Also, indicators of consistency (hardness, adhesiveness, adhesion force and rigidity) decreased by 1.1–1.7 times (upon a mass fraction of dry skim milk residue of 7 and 10%). The samples of ice cream subjected to lactose hydrolysis were characterized by a high dispersion of structural elements typical for a traditional product, and by improved texture and increased sensation of sweetness. The complex of investigations to study quality indicators of ice cream with the fat mass fraction of 15% showed that a change in the mass fraction of dry skim milk residue upon enzymatic hydrolysis of lactose results in formation of different structural-mechanical and sensory indicators that should be considered during the creation of assortment and development of formulations of low-lactose products.