Casein is a family of related phosphoproteins, including αS1, aS2, β, κ. It is typically found in mammalian milk. In cow’s milk, around 80% of the proteins are casein. In human milk, about 20%-60%.
Extraction and Properties
Casein is extracted from skim milk using three methods.
- Fermentation of milk sugar by Streptococcus lactisi. This helps to produce lactic acid, and casein will coagulate and accumulate.
- Precipitation of acid casein by adding dilute hydrochloric acid or sulfuric acid.
- Warm skim milk is set with rennet extract, and calcium paracaseinate coagulates.
Pure casein is an amorphous white solid without taste or odour; Commercial casein is light yellow with a pleasant smell. It contains many proline amino acids and is poorly soluble in water.
Industrial uses
It is commonly used as a food additive. A common form of casein is sodium caseinate, and it can be used as a food stabiliser. Another form of casein is calcium caseinate, and it usually is used to increase the calcium content and lower the sodium content in a food product.
Risks
Casein Allergy
Epidemiology:
It varies over region and time. And it relates to many factors. A study shows that it is about 5.2 % of prevalence. And in the high-income cohort, it is 9.2%, whereas it is 1.5% in the low-income cohort.
Symptoms:
- Skin symptoms: urticaria; angioedema;
- Respiratory symptoms: difficulty breathing, coughing, and wheezing;
- Gastrointestinal symptoms: abdominal pain, vomiting, and diarrhoea;
- Cardiovascular symptoms: dizziness, confusion, and hypotension.
Pathogenesis:
Immunoglobin(Ig) E and non-IgE mediated reaction.
Diagnosis:
The doctor will ask about the medical history of eating habits and symptoms and then perform related skin tests and blood tests. Also, if need to further confirm the diagnosis, the provocation test will be conducted to rule out any doubts.
Treatment:
- Drugs include antihistamine and epinephrine, depending on the severity of the situation.
- Avoid milk and other dairy products.
Foods That Contain Casein
| Milk that may casein | Processed foods may contain casein | Other sources of casein |
| Acidophilus milk | Brown sugar flavouring | Butterfat |
| Condensed milk | Bavarian cream flavouring | Caseinate |
| Evaporated milk | Caramel coloring | Cheese (hard and soft) |
| Dry milk | Chorizo | Cream |
| Goat milk | Coconut flavoring | Custard |
| Low fat milk | Hot dogs | Ice cream |
| Malted milk | Luncheon meats | Lactose |
| Milk powder | Natural chocolate flavoring | Pudding |
| Milk solids | Sausages | Rennet casein |
| Skim milk | Whey | |
| Whole milk | Yogurt |
Conclusion
Casein can offer several benefits, especially for infants or adults who do resistance training. A casein supplement can support muscle growth, but in many cases, it’s not necessary, especially in special needs kids. Many studies show that casein-free diets are effective as a therapy for autistic children, especially on measures of physiologic functioning, behaviour problems and autism symptoms.
However, there is still little significant evidence about the study population, and the clinical trial design still needs further improvement. If parents are considering a casein-free diet or other diets to implement in their children’s daily lives, they need to consult their nutritionist and child psychiatrist to ensure they have adequate nutrition and vitamins.
References:
1. Miller MJ, Witherly SA, Clark DA. Casein: a milk protein with diverse biologic consequences. Proc Soc Exp Biol Med. 1990 Nov;195(2):143-59. doi: 10.3181/00379727-195-43129. PMID: 2236098.
2.C Kunz, B Lönnerdal, Human-milk proteins: analysis of casein and casein subunits by anion-exchange chromatography, gel electrophoresis, and specific staining methods, The American Journal of Clinical Nutrition, Volume 51, Issue 1, January 1990, Pages 37–46, https://doi.org/10.1093/ajcn/51.1.37
3.https://www.britannica.com/science/casein
4.Mousan G, Kamat D. Cow’s Milk Protein Allergy. Clin Pediatr (Phila). 2016 Oct;55(11):1054-63. doi: 10.1177/0009922816664512. Epub 2016 Aug 31. PMID: 27582492.
5.Arancibia, María E.∗; Lucero, Yalda∗,†; Miquel, Isabel∗; Marchant, Pamela‡; Rodriguez, Lorena∗; Alliende, Francisco∗; Ríos, Gloria∗; Maturana, Andrés§ Association of Cow’s Milk Protein Allergy Prevalence With Socioeconomic Status in a Cohort of Chilean Infants, Journal of Pediatric Gastroenterology and Nutrition: September 2020 – Volume 71 – Issue 3 – p e80-e83
doi: 10.1097/MPG.0000000000002787
6.Piwowarczyk A, Horvath A, Łukasik J, Pisula E, Szajewska H. Gluten- and casein-free diet and autism spectrum disorders in children: a systematic review. Eur J Nutr. 2018 Mar;57(2):433-440. doi: 10.1007/s00394-017-1483-2. Epub 2017 Jun 13. PMID: 28612113.