Comparative Analysis of Drying and Preservation Techniques for Whey Powder: Enhancing Physicochemical and Functional...

Whey is commonly used in powder form in various dairy and food products, including whey-based beverages, yoghurts, sports supplements and bakery items such as cakes and waffles. As a by-product of cheese production, incorporating whey into foods supports both economic and environmental sustainability while enhancing their nutritional and functional qualities, primarily due to its high serum protein content. This study investigates the effects of different technologies, such as spray drying, freeze-drying, and encapsulation combined with freeze-drying, on the functional and nutritional properties of whey. The primary objective is to identify the most effective processing method for preserving the physicochemical and functional integrity of whey.

Comprehensive analyses were conducted on individually processed and reconstituted whey samples, including the assessment of pH, titratable acidity, dry matter, protein, ash and fat contents, as well as water-holding capacity, rheological behaviour, colour attributes, antioxidant activity and total phenolic content. By comparing the analysis results, the most suitable application was identified based on technological, sensory and functional criteria.

Encapsulation combined with freeze-drying was the most effective method, significantly enhancing functional properties. This treatment resulted in the highest antioxidant capacity (1.62 mM Trolox) and water-holding capacity (4.65 %), while largely preserving phenolic compounds (expressed as galllic acid equivalents (GAE), 1.09 mg/mL) and protein content (0.82 %). It also produced the highest consistency index (0.448), indicating improved structural stability. Freeze-drying alone effectively maintained phenolic content (expressed as GAE, 1.13 mg/mL), colour (L*=46.95) and nutritional quality, while improving water-holding capacity (3.91 %) compared to untreated whey. In contrast, spray drying, despite its industrial advantages, resulted in notable reductions in phenolic content (expressed as GAE, 0.82 mg/mL) and antioxidant capacity (0.020 mM Trolox), along with a darker colour (L*=39.5), likely due to thermal degradation. All drying methods increased dry matter content, particularly in encapsulated samples (16.33 %). Overall, encapsulation combined with freeze-drying provided the best balance of functional, nutritional and physicochemical properties, making it a promising approach for enhancing whey stability and shelf life.

These findings highlight the potential of alternative drying and preservation technologies, particularly encapsulation combined with freeze drying, for the sustainable valorisation of whey in functional food applications.