Cheese on a low-lactose diet

by Anita MacDonald and Pat Portnoi. This article first appeared in Network Health Dietitians in April 2009.

There are hundreds of types of cheese produced throughout the world. Some mature hard cheeses are known to be low in lactose but there is a scarcity of analysis data, and any existing information is inconsistent and variable. Inclusion of cheese in a low lactose diet is difficult without quantitative information about its lactose content. It would be useful to be able to include mature hard cheese in a low lactose diet: it is versatile, will add variety, increase palatability and enhance the nutritional quality of the diet.

Galactosaemia
In galactosaemia, a rare, inherited metabolic disorder, patients have to follow a life long lactose-free diet. Traditionally, mature hard cheese was always excluded in the diet until a UK medical advisory panel (a group of dietitians, clinicians, biochemists and others) for the Galactosaemia Support Group commissioned the lactose/galactose analysis of 13 different cheeses available in the UK. This work is soon to be published in the Journal of Human Nutrition and Dietetics, but we can give you a sneak preview of some of the findings. This information will be valuable for all patients following a low lactose diet.

Cheese production
Many factors influence the final lactose content of cheese such as the different fermentation times, types of starter culture and other variations in cheese production.

Cheese is made by coagulating milk. This transfers milk into a semi-solid mass and separates milk into solid curds and liquid whey. Cow’s milk is ideal for cheese-making because it contains high levels of casein which is required to provide an adequate coagulum. Most cheeses contain high levels of casein but low levels of whey. It is whey that is particularly rich in lactose. Whey contains 70% lactose, and casein no more than 1% lactose. In fact the origin of the word cheese appears to be the Latin caseus, from which the modern word casein is derived.

Lactose is reduced in cheese by two important production processes:

1) separation and removal of whey by drainage and

2) the fermentation of lactose by bacteria.

The lactase in lactic acid bacteria readily breaks down lactose and uses glucose as an energy source. Furthermore, some lactic acid bacteria are able to convert galactose to glucose.

Some cheeses have a starter culture of bacteria added that increases lactic acid content and so reduces lactose concentrations. The temperature of coagulation, starter culture, coagulating enzyme and the acid produced, influences the properties of the curd and degree of whey expulsion, and hence the final lactose content.

When the cheese or curd is set into a moist gel, some soft or processed cheeses are essentially completed, so they are drained, salted and packaged and are likely to contain significant amounts of lactose. However, for harder cheeses, the curd is cut into small cubes, which allows fluid to drain from the individual pieces of curd. This speeds whey expulsion and so further reduces lactose content.

Generally the longer the cheese has matured the lower the lactose content. Maturation of cheese can last from a few days to several years. The cheeses are exposed to a temperature and humidity controlled environment for a specified length of time. During ripening hydrolysis of lactose occurs, the extent of which is influenced by the starter culture and any variations in process.

Can the lactose content of cheese types vary?
Cheese is a biological medium, and the lactose content of cow’s milk is subject to seasonal variation. However, in some low lactose cheeses, at day one following cheese manufacture, most of the lactose should be removed in the whey. For example, in well drained cheese such as Swiss types, lactose is completely used up in a few hours by the propionic bacteria.

Lactose analysis of cheese
Since 2001, the UK Galactosaemia Support Group has commissioned the analysis of 119 samples of 13 cheese types, in nine batches. They defined a low lactose cheese as a cheese containing undetectable quantities of lactose (< 10mg/100g lactose). For galactosaemia, it also has to be galactose free. The cheese samples analysed were purchased from retail outlets at different times throughout the year to try to detect any seasonable variability. The low lactose cheeses have been reanalysed over the years to check the consistency of the results obtained. The analysis was performed by two different laboratories (LGC Ltd, and Leatherhead Food International).

The cheese samples were homogenised, sugars extracted using water or 40% alcohol for fatty samples, and samples deproteinised. Enzymatic analysis using the lactose/D-galactose Boehringer Mannheim Test-Combination kit, measuring light absorbance was conducted on filtered extracts.

Cheeses containing undetectable quantities of lactose (<2.8 mg/100g, LFI analysis; <10 mg/100g, LGC Limited analysis) and galactose were: Gruyere (5 samples); Emmental (block, sliced and grated) (16 samples); Jarlsberg (6 samples); Parmigiano Reggiano and Grana Padano / Italian Parmesan (block and grated) (16 samples); and mature Cheddar cheese from the UK West Country Farmhouse Cheese Makers Association (35 samples) only.

Therefore, Gruyere, Emmental, Jarlsberg, Italian Parmesan (Parmigiano Reggiano and Grana Padano), and mature Cheddar cheese produced in one area of England where the manufacturing process is standardised and guaranteed are now allowed in the UK galactosaemia diet and are suitable for other low lactose diets.

Cheeses that contained lactose, and therefore were unsuitable, included other mature and mild Cheddar cheeses, Gouda, Edam, BabyBel Emmental, Brie and processed cheeses (cheese triangles and cheese spread).

Why West Country Farmhouse Mature Cheddar only?
Although other types of mature Cheddar cheese (12 months or more maturity) are likely to be low in lactose, the results of the lactose analysis performed were more variable than the analysis of the mature cheddar cheese produced by the West Country Farmhouse Cheese Makers Association.

There are seven farms that produce Mature Cheddar Cheese who are part of this Association. They all guarantee the production and storage of their mature Cheddar cheese in the same traditional manner and is carefully controlled. Their cheese is identified by the protected European designation of origin (PDO) seal on their label. It is granted to products whose entire manufacturing process takes place in a limited geographical area. West Country Cheese Farmhouse Cheese is currently supplied to some supermarkets (Waitrose, and Booths usually stock a good selection) as well as other independent retailers.

Patients and carers need to check their West Country mature cheddar cheese label displays the PDO seal.

Is all Parmesan lactose free?
American Parmesan is aged for only 10 months and is likely to be higher in lactose and should not be used in galactosaemia or low lactose diets. However, the Parmesans analysed for the study were either Parmigiano Reggiano or Grana Padano. Parmigiano Reggiano is made in a specific section of Northern Italy and it has its own EU PDO. It is likely to have been matured for over two years. Grana Padano is an Italian cheese very similar to Parmigiano Reggiano but it is aged for 15 months or more.

In conclusion, the lactose content of over 119 cheese samples from 13 cheese types have been analysed for their lactose and galactose content. Five cheese types (Gruyere, Emmental, Jarlsberg, Parmigiano Reggiano and Grana Padano and West Country Farmhouse mature Cheddar) have been identified to have consistently low lactose content when repeated analysis has been conducted. These cheeses should be suitable for any patient with lactose intolerance as well as galactosaemia. As far as Wallace and Gromit are concerned, we did not analyse Wensleydale cheese for its lactose content – so sorry to disappoint all ‘Wallace’ fans!

References
Portnoi P, MacDonald A (2009) Determination of the lactose and galactose content of cheese for use in the galactosaemia diet. Journal of Human Nutrition. Accepted for publication and in press.
Baboin-Jaubert A (2003). Handbook of cheese. Hachette, London.
Ridgeway J (2004) The Connoisseurs Guide to Cheese. Quintet Publishing

Dr Anita Macdonald is one of the UK’s top paediatric dietitians; she specialises in inherited metabolic disorders.
Pat Portnoi has worked as a specialist dietitan with the Galactosaemia Support Group since 1998.

First published in 2009

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