Probing the cumulative effects of unit operations and lactose to whey protein ratios on protein modifications in powdered model infant formula

Abstract

The impact of lactose to whey protein ratio on processed-induced protein modifications was investigated in powdered model infant formula. Model samples were prepared with different lactose to whey protein ratios and different total protein concentrations; protein modifications were evaluated before, during and after processing. Lab-scale equipment was used to mimic commercial manufacturing, and a powdered young-child formula was included to elucidate cumulative effects of commercial unit operations. Maillard-related and structural protein modifications were affected differently by unit operations, both in model samples and commercial formula. Maillard reaction products (furosine, α-dicarbonyls and advanced glycation end products) increased with increased lactose content of model samples, whereas absence of lactose facilitated formation of disulphide-linked aggregates, lysinoalanine and lanthionine. The lowest level of protein modifications was observed at a 30:70 lactose to whey protein ratio, suggesting partial dry blending of lactose as a feasible approach to improve protein quality in powdered infant formula.