Cold enzymatic bleaching of fluid whey

Area of Science:

• Food Science
• Dairy Technology
• Biocatalysis

Background:

• Chemical bleaching of whey using hydrogen peroxide (HP) requires high concentrations and can generate undesirable off-flavors in final whey protein products.
• Enzymatic bleaching using naturally present lactoperoxidase or exogenous commercial peroxidase (EP) at cold temperatures presents a potential alternative to chemical methods.

Purpose of the Study:

• To determine the optimal hydrogen peroxide (HP) concentration for enzymatic bleaching of fluid whey and retentate at 4°C.
• To compare the bleaching efficacy and sensory characteristics of enzymatic bleaching with traditional HP chemical bleaching.
• To evaluate the impact of different bleaching treatments on the manufacture of 80% protein whey protein concentrate (WPC80).

Main Methods:

• Fluid Cheddar whey and retentate (80% protein) were manufactured and subjected to various bleaching treatments at 4°C.
• Optimal HP concentration for enzymatic activation was determined by quantifying norbixin loss.
• Bleaching efficacy, descriptive sensory analysis, and volatile compounds were monitored for different treatments, including a control.

Main Results:

• Enzymatic bleaching demonstrated faster kinetics and higher bleaching efficacy (color loss) compared to HP alone at 250 mg/kg.
• Retentate bleached more rapidly than fluid whey due to higher lactoperoxidase concentration.
• Spray-dried WPC80 from bleached wheys exhibited a lack of sweet/buttery flavors and a cardboard flavor, with specific volatile compounds differing based on the bleaching method.

Conclusions:

• Enzymatic bleaching at 4°C is a viable and potentially desirable alternative to HP bleaching for fluid whey and retentate.
• The choice of enzymatic source (native lactoperoxidase vs. EP) influences bleaching time and the profile of volatile compounds in the final WPC80 product.