Take home message
- Whey is widely used in sports. It supports the building muscle tissue.
- Whey, which has not been heated, denatured or where the whey proteins have not been agglomerated, have higher protein quality
- Raw milk whey gives better sports performance as measured by muscle strength in laboratory animals.
Whey, as a cheese by-product, was a waste product, which was returned to the farm for calves, or in mixed farms was fed to pigs. In cheese-making, the milk curdles, and the cheese casein clumps together to build a thick pudding. This is done by rennet, which is extracted from the abomasums of young calves. The rennet contains enzymes that make the milk flocculate. During cheese-making large amount of whey are releases, which serves as a raw material for the food industry but is also a highly valued product in the fitness industry. Fat-free whey is used for muscle recovery and muscle building.
Whey is heated at high temperatures
In whey processing, the product is thickened into whey powder; the water is extracted by evaporation or spray drying. In the process, the whey is usually heated to high temperatures; at the intake temparatures are at 90-100o C, the drying itself is more likely to be at 160-200o C. In an alternative processing, whey powder was prepared by filtration and freeze-drying. The final temperature does not exceed the cow’s body temperature. Fresh, warm milk is no more than 37-38o C. As a result, denaturation and aggregation of proteins does not take place, and the range of heat-sensitive whey proteins remain intact. Whey proteins include beta-lactoglobulin (BLG), alpha-lactalbumin (ALA), bovine serum albumin (BSA), and a variety of immunoglobulins (IGG).
Muscle strength
In humans about 40% of their weight consists of muscle mass. With ageing or malnutrition, this may decrease (significantly). Korean researchers (Kim et al., 2023) assessed the effects of heating whey on muscle strength and muscle gain. Three-week-old rats were fed one of the two whey powders, either heated or not, as a supplement to their normal ration. The animals received 1.56 g of additional protein per kg live weight, for 8 weeks. In addition, there was a control group not receiving whey.
Changes in weight, fat accumulation and leg muscle strength (‘grip strength test’) were assessed. There was no difference in weight gain, feed intake or feed conversion between the two whey groups. The raw whey group (RAW) had less nitrogen excretion in urine than the heated whey group (COOKED), higher utilisation of nitrogen from feed and thus raw whey had higher biological value for the animal. The groups had equal fat mass, but the RAW group had gained 5.4% more muscle mass than the COOKED group. Two small muscles in the hind legs (the Soleus and Plantaris) were almost 16% and more than 7% heavier in the RAW group, respectively. At weeks 4 and 8, muscle strength was tested in the animals. At week 4, there was no difference, but at week 8, muscle strength increased to 588 g in the RAW group, which was 8% higher than in the COOKED group (541 g).
Leucine
Leucine is one of the 20 amino acids. It is known that this amino acid is important in tissue repair, and muscle building. Yet there was no difference in blood levels of the amino acid leucine between the two groups. The Korean researchers concluded that raw whey does have advantages over heated whey. In particular, the protein quality is better, leading to the animals being able to build a larger muscle mass.
