ANALYTICAL METHODS FOR EVALUATING LACTOSE HYDROLYSIS IN ICE CREAM MIXES

Lactose directly influences the texture and flavor of ice cream. Its hydrolysis into glucose and galactose is interesting for application in ice cream, as the monomers glucose and galactose are sweeter carbohydrates and more soluble in water. Cryoscopy is a method often used to monitor the hydrolysis of lactose in milk, while the glucometer has been studied to quantify lactose by measuring the glucose, resulting from hydrolysis. However, the effectiveness of these techniques to monitor lactose hydrolysis in ice cream mixes has not yet been evaluated. Therefore, the present study aimed to evaluate the efficacy of analytical techniques, such as cryoscopy, glucometer and soluble solids (Brix), in determining lactose hydrolysis in ice cream mixtures. Six formulations were prepared (composed of pasteurized milk, powdered milk, sucrose, glucose syrup, stabilizer and emulsifier), with β-galactosidase concentrations ranging from 0 to 10 (g/L). The mixtures were matured at 4°C for 16 hours and subsequently subjected to heat treatment (65°C/30 minutes) for enzyme inactivation. The mixtures were evaluated for lactose concentration (HPLC - RID), cryoscopy, Brix (benchtop densimeter) and glucose concentration (glucometer, G-Tech Lite). The degree of hydrolysis was determined from the lactose concentration, measured by HPLC. The experiment was carried out in three replications, and the data analysis was performed using the R. Studio software. The mixture without the addition of the enzyme contained 5.29 % lactose, while the hydrolyzed mixtures showed values between 1.60 and 1.76 % after 16 hours, corresponding to a degree of hydrolysis that ranged from 65.9 to 69.5 %. A strong correlation was found between the degree of hydrolysis and the results of cryoscopy (R² = 0.96), Brix (R² = 0.94) and glucometer (R² = 0.81), consistent with the increase in glucose and soluble solids as a function of hydrolysis, also impacting the freezing point. A similar correlation was found between the reference lactose values (HPLC) and the other methods: cryoscopy (R² = 0.97), Brix (R² = 0.95) and glucometer (R² = 0.77). The results obtained are promising, indicating that methods such as cryoscopy, glucometer and Brix can be optimized and validated to industrially monitor lactose and its hydrolysis in ice cream mixtures, offering fast and efficient alternatives.