Control of heat treatment and storage temperature prevents the formation of visible aggregates in acidic whey dispersions over a 6-month storage period

- Visible precipitates of protein aggregates in acidic whey protein isolate dispersions develop during storage.
- Control of heat treatment and storage temperature can prevent aggregate formation.
- Shelf-life stability >6 months can be obtained for 70 g protein L−1 solutions.
- Batch-to-batch variations may be due to differences in the levels of divalent cations.

Acidic whey protein isolate (WPI) dispersions are widely applied for translucent whey-based beverages. However, developing beverages that maintain clarity during extended storage can be a challenge. The formation of visible aggregates occurs recurrently during storage, leading to reduced consumer satisfaction. Batch-to-batch variation with respect to the degree of aggregation also is observed, which impairs shelf-life determination. In this study, two WPI batches (A and B) with different levels of visible aggregate formation during the storage of acidic dispersions were analyzed. Visual evaluations, oscillatory rheology, and absorbance measurements (A500) were applied to assess the formation of visible aggregates in 70 g protein L−1 WPI dispersions during a 6-month period. It was shown, that by changing the heat treatment from the conventional conditions of 95 °C for 180 s to 120 °C for 20 s and/or lowering the storage temperature from the conventional 20 °C-4 °C, the formation of visible aggregates was prevented over the 6-month storage period. The protein composition of the aggregates and the surrounding clear liquid was analyzed by 2-dimensional gel-electrophoreses. The visible aggregate was highly enriched by a low pI spot, possibly containing caseinomacropeptide and/or proteolytically truncated fragments of β-lactoglobulin and α-lactalbumin.