Developing low-lactose milk powder: A multi-enzyme approach to reduce Maillard browning

Preparation of low lactose milk and milk products have attracted the attention of consumers due to increasing prevalence of lactose intolerance. However, the physico-chemical properties of product prepared from the single enzyme application (β-galactosidase) possess a significant concern of Maillard browning. While previous studies adjusted spray drying conditions to address Maillard browning in low lactose powder, our research introduces a multi-enzyme system for lactose hydrolysis in concentrated skim milk to produce a spray-dried powder with reduced browning. Glucose oxidase (GOX) converts glucose into gluconic acid that lowers down the concentration of Maillard reaction products (MRP's) formed during manufacture of lactose hydrolysed milk products. The activity of GOX was enhanced when used along with catalase (CAT). Use of GOX + CAT in buffer solution (containing 9 % glucose) exhibited 61.44 % glucose reduction after 22 h of reaction. GOX (70 U/ml) along with CAT (25 U/ml) when added to milk after 5 h of β-galactosidase (9.53 U/ml) action resulted in significantly higher reduction of glucose (53.95 %) after 20 h with final milk pH of 6.5. Spray dried powder prepared using optimised multi-enzymes (β-galactosidase and GOX + CAT) treated milk revealed reduced browning characteristics i.e., 12.85 browning index as compared to the powder prepared from milk treated with β-galactosidase alone (16.37).

Industrial relevance: The use of GOX + CAT during lactose hydrolysis could serve as a potential approach for mitigating browning characteristics in low-lactose milk and milk products. The multi-enzymatic system used to produce low-lactose milk can be easily adapted by large-scale industries to produce a powder with physico-chemical properties similar to traditional skim milk powder.