MooScience: the science of milk

Acid Whey FAQ


Do you want to know more about acid whey? Read on to find the answers to some of your frequently asked acid whey questions!


What is the controversy about acid whey?

Acid whey is the major by-product from making Greek yogurt, cottage cheese, some types of cheeses and other fermented milk products. Mooscience: Where does acid whey come from? drawn by Susan Fluegel

Picture: Cows that milk acid whey have some serious attitude.

Since it is hard to use acid whey in food products; excess acid whey may be misused or dumped illegally. This has created a controversy over the ethics of making products, such as Greek yogurt, that generate a lot of acid whey waste. Luckily, acid whey can be used for other applications and does not have to be discarded.

What is wrong with acid whey?

Nothing is wrong with acid whey except its name. It is a high value food product. Acid whey contains many nutritional components which can improve or support health. These beneficial components include vitamins, minerals, branched chain amino acids, lactoferrin, lactose, lactic acid, alpha-lactalbumin, and many other bioactive milk products.

What is the difference between sweet whey and acid whey?

Acid whey is the liquid that is leftover when diary producers make yogurts or soft cheeses. It is called acid whey because it is more acidic than sweet whey. Sweet whey is the liquid that is leftover when dairy producers make hard or rennet cheeses. It is called sweet whey because it contains a high concentration of lactose, a milk sugar, and because it had the foresight to hire an image consultant.

Acid whey also contains lactose. However, some of the sweet lactose has been transformed into lactic acid. Acid whey is safe to eat and contains many valuable nutrients. Both acid and sweet whey have many health benefits.

Fun fact: Acid whey normally has a pH of around 4.3 - 5.1. Many foods have a lower pH. However, you never hear anyone referring to fruit as acid apples.

  • Apples have a pH of 3.3 - 4.0
  • Bananas have a pH of 4.5 - 5.2
  • Blueberries have a pH of 3.1 - 4.5
  • Cream cheese has a pH of 4.1 - 5.0

MooScience, apples are more acidic than acid whey.

Picture: Gala apple on cut wood stump. This tasty red striped fruit is more acidic than acid whey.


What is normally done with excess acid whey?

Human Food:  Acid whey can be dried and used to make whey protein concentrates.  Liquid acid whey can also be used directly as a healthy additive in food products. 

Acid Whey Contains Other Useful Nutrients: Both lactose and lactic acid can be used in food processing. Food scientists are working on processes to economically remove the lactose, lactic acid and minerals from acid whey.

Animal Food: Some farmers feed acid whey to livestock such as pigs, chickens or cattle. It is mixed in with other food or served neat in liquid form. Animals, especially pigs, like the taste of whey. Hogs love a whey drink straight up or with a chaser of corn mash.

Fertilizer: Acid whey can be used to fertilize croplands. Some people complain that this can result in a sour ‘old beer like’ smell coming from the field. Whether or not this is a problem most likely depends on how fond you are of the smell of spilt beer and run down roadside bars.

Electricity: Acid whey can be used in an anaerobic digester to make electricity. Anaerobic digesters use helpful bacteria to ferment acid whey along with other substances, such as manure. This creates stinky biogases, such as methane, that can be converted into electricity. Needless to say, this is a much better use for the odorous greenhouse gases than being released into the atmosphere or serving as an audible punch line for eight year old boys' performing fart jokes.

Anaerobic digesters consume excess acid whey and provide people’s electrical needs. Some cheese and yogurt plants use large anaerobic digesters to meet all or most of their energy needs. Although this is a good use for a waste product, it is a shame to use a valuable food product, whey, as biofuel.

MooScience: ducks swim in algea bloom. Illegal dumping of acid whey can cause water pollution.Waste:  Due to media scare tactics, some people believe that acid whey is dumped freely into streams and watersheds. Environmental regulations prohibit food manufacturing plants from dumping food products into sensitive aquatic environments. 

Acid whey cannot be dumped into sewers, streams or watersheds. One reason for this is that if a large quantity of whey was dumped into a body of water, the biological oxygen levels in the water would plummet. When oxygen levels in water drop it results in a massive die-off of the marine life dependant on that oxygen.

Fish and other marine organisms do not die because acid whey is 'toxic'; dumping a large amount of any biological matter or food into a stream or lake will have similar results. This is because aerobic bacteria in the water use dissolved oxygen to break down organic matter. Organic matter includes foods like whey. If you dump a large amount of organic matter into a body of water the bacteria rush over to start digesting it. They pull oxygen out of the water which means that the oxygen level of the lake or stream drops. It is the oxygen depletion that kills marine life.

The amount of oxygen needed by the bacteria to to break down organic matter at a given temperature is known as biological oxygen demand (BOD). Higher BOD readings result in more oxygen being pulled out of the water. Due to its high organic load, cheese whey, including acid and sweet whey, has a BOD of 27-60 g L-1 of oxygen per liter (Carvalho et al. 2013).

Waste Water Treatment Plants: Some waste water treatment plants take a limited amount of acid whey to use in their waste stream. This is tightly regulated.

Constructed Wetlands: There has been some interest in using constructed wetlands to treat cheese whey effluents. I assume they would plant milkweed.


What is the BEST thing to do with excess acid whey?

The best thing to do with acid whey is to use it in human food. Acid whey contains many healthy compounds such as lactic acid, lactoferrin, whey proteins and other nutrients. Studies have shown that whey and dairy compounds strengthen the immune system (Legrand et al. 2012), improve immune reactions in people with asthma (Lothian et al. 2006, Chen et al. 2013), have anticancer properties (Pepe et al. 2013), promote weight loss along with lean tissue growth (Frestedt et al. 2008, Coker et al. 2012), and lower high blood pressure (Fluegel et al. 2008).



  • Carvalho F, Prazeres AR, Rivas J. Cheese whey wastewater: Characterization and treatment. Science of the Environment. 2013;445-446:385-396. Pubmed. doi: 10.1016/j.scitotenv.2012.12.038.
  • Chen JH, Huang PH, Lee CC, Chen PY, Chen HC. A bovine whey protein extract can induce the generation of regulatory T cells and shows potential to alleviate asthma symptoms in a murine asthma model. Br J Nutr. 2013; 28;109:1813-20. Pubmed. doi:10.1017/S0007114512003947
  • Coker RH, Miller S, Schutzler S, Deutz N, Wolfe RR. Whey protein and essential amino acids promote the reduction of adipose tissue and increased muscle protein synthesis during caloric restriction-induced weight loss in elderly, obese individuals. Nutrition Journal. 2012;11:105. Pubmed. doi: 10.1186/1475-2891-11-105 (full paper).
  • Frestedt JL, Zenk JL, Kuskowski MA, Ward LS, and Bastian ED. A whey-protein supplement increases fat loss and spares lean muscle in obese subjects: a randomized human clinical study. Nutrition & Metabolism, 2008;5:8. Pubmed. doi: 10.1186/1743-7075-5-8 (full paper).
  • Fluegel SM, Shultz TD, Powers JR, Clark S, Barbosa-Leiker C, Wright BR, Freson TS, Fluegel HA, Minch JD, Schwarzkopf LK, Miller AJ, Di Filippo MM. Whey beverages decrease blood pressure in prehypertensive and hypertensive young men and women. International Dairy Journal, 2010;20:753. doi: 10.1016/j.idairyj.2010.06.005
  • Lothian JB, Grey V, Lands LC. Effect of whey protein to modulate immune response in children with atopic asthma. Int J Food Sci Nutr. 2006;57(3-4):204-11. Pubmed.
  • Pepe G, Tenore GC, Mastrocinque R, Stusio P, Campiglia P. Potential Anticarcinogenic Peptides from Bovine Milk. J Amino Acids. 2013:2013:939804. Pubmed. doi: 10.1155/2013/939804 (full paper).