See also, Barley f6

Malt is made most often from Barley, but sometimes from other grains such as Rye. Malting is the controlled germination of cereals, followed by the termination of this process by the application of heat. Further heat is then applied to "kiln" the grain and produce the required flavour and colour.

The malting process usually involves soaking the raw grain in water for 48 hours, then spreading it out to allow it to germinate for several more days.

Then it is moved to the "kiln" where hot air is forced through it, drying and roasting it so that all biochemical activity stops and flavour develops. The Barley is now considered Malt, a mellow, slightly sweet-flavoured powder.

The maltster's task is to get the grain to develop to a certain point, and then stop the process, "locking it up" by the use of heat. The brewer will then "unlock" the process when he mashes his milled Malt and completes the conversion to sugars which will feed the yeast to produce alcohol. Other characteristics in the Malt make strong contributions to the quality of the final beer.

Malt that has been dried at low heat is the basic ingredient for most beer, but small amounts of specialty Malts are used to give added colour and flavour. Specialty Malts are made by drying at higher temperatures to give darker colour and other special characteristics. Malt is also used for making whiskey, for flavouring. Some by-products of the malting process are added to flours to boost fibre and protein. But the main constituent is starch.

There is basically no difference between brewer's Malt and malted milk. During Prohibition, many brewers and maltsters stayed in business by producing Malt for the “malteds” enjoyed in soda shops.

Malt has many uses, including making vinegar, brewing beer, and distilling liquor. Malt is also a nutritious additive to many foods. Malted-milk powder and Malt vinegar are two of the most popular Malt products.

IgE-mediated reactions

Malt may uncommonly induce symptoms of food allergy in sensitised individuals, including Baker's asthma, urticaria, facial itching, Quincke edema, systemic symptoms and anaphylaxis. Symptoms usually occurred after the consumption of Malt-containing chocolate drinks and Malt-containing snack products (1).

A 21-year-old atopic woman developed urticaria, angioedema of the face, and wheezy dyspnea shortly after drinking beer and eating a Maize-based snack. Skin-specific IgE was detected, and specific IgE measurements with beer, Barley, Malt, Wheat, Maize, Rye, Rice, and Oat flour were positive. This patient developed type I hypersensitivity to Barley/Malt and Maize. Although she also showed IgE reactivity to Wheat and other cereals, no symptoms were elicited upon ingestion of these cereals, probably indicating latent sensitisation to them (2). Urticaria as a result of drinking beer has been reported in three individuals (3).

Two cases of severe systemic reactions due to beer ingestion have been reported: 1 of anaphylaxis and 1 of generalised urticaria and angioedema. Special investigation, in particular skin- and serum-specific IgE determination, showed that Barley was the specific ingredient responsible for the observed allergic reactions to beer (5).

Other reactions

Barley grain contains a protein that cross-reacts with Wheat gluten in those prone to coeliac disease. Usually, these patients are advised to avoid Malt.  At present, there is no proof that Barley Malt provokes coeliac symptoms, but it may be prudent for these patients to avoid Malt because of the possible gluten-like residues.

Allergenic Molecules

The following allergens have been characterised from Barley, and may be present in Barley Malt:

• Hor v 1, a 14.5 kD protein
• Hor v 9, a 30 kD protein

Several IgE-binding allergens of 31-56 kDa have been detected in Malt and Barley extracts. A major protein of 38 kDa has been isolated from beer extract (2).  In sera from patients with urticaria from beer, 5-20 kDa allergens were isolated from a beer protein fraction. Patient IgE bound only the 10 kDa protein in beer and Malt, whereas a main 16 kDa protein was demonstrated in Barley in addition to a very faint 10 kDa protein band. The major Barley allergen, responsible for Baker’s asthma, is a 16 kDa Barley protein (3). 

Cross Reactivity

An extensive cross-reactivity among the different individual species of the genus of Barley could be expected, and this may result in cross-reactivity if the protein remains intact in the malting process (5).

In a patient who developed allergic symptoms shortly after drinking beer and eating a Maize-based snack, inhibition assays showed that the Malt extract was able to inhibit most of the IgE-binding proteins in Wheat and Maize extracts, whereas Maize did not produce significant inhibition to Barley and Malt extracts. This patient displayed immediate hypersensitivity to Barley/Malt and Maize) (2).

Last reviewed : June 2022