Effects of spray drying and freeze drying on the protein profile of whey protein concentrate
These findings suggest that for large-scale whey protein concentrate (WPC) production, spray drying may be a more cost-effective method without compromising the retention of bioactive proteins, assuming multiple pasteurization steps are already part of the process. This information can help the dairy industry make informed decisions to optimize the nutritional value and quality of their whey protein products.
College of Health researcher(s)
College unit(s)
Abstract
Whey protein concentrate (WPC) is consumed for its high protein content. The structure and biological functionality of whey proteins in WPC powders may be affected by the drying technique applied. However, the specific impact of spray drying and freeze drying on the overall protein profile of whey protein derived from sweet whey streams at scale is unknown. Herein, we examine the effects of commercial-scale freeze drying and spray drying on WPC to determine which method better preserves bioactive whey proteins, with the goal of helping the dairy industry create high-value products that meet the growing consumer demand for functional dairy products. WPCs were produced from pasteurized liquid whey using either a commercial spray dryer or freeze dryer. A variety of analytical techniques, including enzyme-linked immunosorbent assay, polyacrylamide gel electrophoresis, and bottom-up proteomics using liquid chromatography-tandem mass spectroscopy were used to identify, quantify, and compare the retention of bioactive proteins in WPC before and after spray drying and freeze drying. In addition, the extent of denaturation was studied via solubility testing, differential scanning calorimetry, and hydrophobicity assessment. There was little to no difference in the retention or denaturation of key bioactive proteins between spray-dried and freeze-dried WPC powders. There was a higher percentage of select Maillard modifications in freeze-dried and spray-dried powders than in the control. The lack of significant differences between spray drying and freeze drying identified herein indicates that freeze drying does not meaningfully improve retention of bioactive proteins compared with spray drying when performed after multiple pasteurization steps.
Practical Application
This study aimed to provide insight into the impacts of spray drying versus freeze drying on whey proteins. Overall, our results indicate that for commercial dairy processing that involves multiple rounds of pasteurization, freeze drying does not meaningfully improve the retention of bioactive proteins compared with spray drying. These findings may help the food and dairy industry make informed decisions regarding the processing of its whey protein products to optimize nutritional value.
Whey Protein Concentrate Drying Methods: FAQ
What is whey protein concentrate (WPC)?
Whey protein concentrate (WPC) is a powdered form of whey, a byproduct of cheesemaking. It is a popular dietary supplement due to its high protein content, typically ranging from 35% to 80% by weight. WPC also contains carbohydrates (including lactose), fats, minerals, and vitamins.
How is WPC produced?
WPC is produced by separating whey from milk during cheesemaking. The whey undergoes several purification steps, including fat separation, pasteurization, ultrafiltration, and diafiltration, to concentrate the whey proteins. Finally, the concentrated whey is dried into a powder using either spray drying or freeze drying.
What are the differences between spray drying and freeze drying?
Spray drying involves atomizing liquid whey into a hot air chamber, causing rapid water evaporation and creating a powder. Freeze drying, on the other hand, involves freezing the whey and then sublimating the ice under vacuum, resulting in a powder with a very low moisture content.
Does the drying method affect the protein profile of WPC?
While both methods can cause protein denaturation, this study found that on a commercial scale, there was little to no difference in the retention or denaturation of key bioactive proteins between spray-dried and freeze-dried WPC powders.
Which method is better for preserving bioactive whey proteins?
This study indicates that for commercial-scale dairy processing, freeze drying does not meaningfully improve the retention of bioactive proteins compared to spray drying, especially when multiple pasteurization steps are involved.
What are Maillard modifications, and how do they affect WPC?
Maillard modifications are chemical reactions between reducing sugars (like lactose) and amino acids in proteins. These reactions can occur during heat treatments like spray drying and can lead to changes in protein structure and functionality, potentially decreasing nutritional value.
Were there any differences in Maillard modifications between the drying methods?
While both freeze-dried and spray-dried powders showed some Maillard modifications compared to the control, the spray-dried WPC had a numerically higher, though not statistically significant, percentage of these modifications.
What are the practical implications of this study for the dairy industry?
These findings suggest that for large-scale WPC production, spray drying may be a more cost-effective method without compromising the retention of bioactive proteins, assuming multiple pasteurization steps are already part of the process. This information can help the dairy industry make informed decisions to optimize the nutritional value and quality of their whey protein products.