Malted Milk Foods

Malted milk food is a product containing milk solids, malt extract and cereal grain flour. Malted milk food was first developed in 1883 by William Horlicks of Racine,Wisconsin, U.S.A. The product was commercially marketed in 1887. This product gained favourable attention from the medical profession and public due to its nutritive value, convenience, digestibility and palatability.

Only a small fraction of milk produced in India has found its place in malted milk manufacture. Though a potential market exists in the country for malt based milk beverages, very few factories have under taken its production. Considerable high cost of these products has largely been responsible in inhibiting its use by common people.

Manufacture of Malted Milk

The preparation of malted milk consists of combining milk with the mash liquor resulting from a mash of barley malt and wheat flour. Barley malt not only supplies the malt flavour, but also contains diastase, which converts starch into sugar. Briefly the process may be divided into the following stages:

i. Production of mash liquor: The malted barely is sieved to remove dust and other foreign matter. It is then crushed using in line roller mill and mixed with high-grade wheat flour. Usually about 2.5 times as much dry barley malt is used as wheat flour. The mix is conveyed to mash tanks, where water at 40°C is continuously added to prepare uniform slurry. The slurry is continuously heated and stirred and the temperature gradually increased to 70°C within about 40 min. The slurry is held at 70°C for about 35 min. During this process the whole of the starch is hydrolysed by diastase, present in malted barley, into maltose,dextrin and malto-dextrins, while the complex cereal proteins are converted into simpler protein substances. The slurry temperature is gradually raised to 78°C and held at this temperature for about 20 min to stop further activity of enzymes and also to achieve maximum cereal solids (28-30%). The mash is

passed through centrifugal separator to remove the insoluble husk and to obtain clear liquor, known as ‘wort’.

ii. Mix preparation: The wort derived from the mashing section is mixed with predetermined quantities of standardised milk, diluted and pasteurised (85°C) malt extract, sugar, salts, minerals and vitamins in a mix preparation tank. Milk solids increase nutritional value of the product by providing high quality fat,proteins, minerals and vitamins. Milk fat enhances flavour and energy level of final product. Malt extract provides desired level of colour and typical caramelised flavour to the finished product. Salts are added to optimise product pH to improve digestibility, enhance flavour and to provide essential salts, especially calcium. The percentage contribution of each ingredient depends upon final formulation of the product.

iii. Evaporation and drying: The mix at about 26% solids is concentrated in the vacuum evaporator until one half to two-thirds of the water content has been removed. The product is then transferred to a steam jacketed evaporator provided with stirring gear, where a high vacuum is maintained, agitation being constant in order to facilitate the removal of the water and to prevent excessive caramelisation. The concentrated mass with an average of 80% solids is finally dried within a level of 2% moisture to a sponge-like, swollen mass usually in a vacuum tray drier. Dried product is cooled in an air-conditioned room to avoid moisture pick up, scrapped off the trays and milled into fine powder. The milled product is conveyed to inline mixers to mix salts, dry vitamins and minerals and then packed in bottles or refill packs.

Malted milk powder will dissolve freely in hot or cold water or milk, the resultant beverage being very palatable besides possessing an agreeable odour and flavor derived from the hydrolysed cereal starch used in its manufacture.

iv. Spray Drying of Malted Milk: The malted milk food is generally prepared by tray-drying method under vacuum that is essentially a batch operation and hence adds to the cost. Spray drying method will reduce the cost of product owing to high volume of continuous and automated operation. Thus the production of good quality, low cost malted milk food with improved physical characteristics like better dispersibility and wettability appears to be better proposition for the dairy industry to consider, than continuing of with the traditional tray-drying method. The concentrate from first stage evaporation at an average 50% solids is atomized using either rotary or nozzle atomising system.

Malt-milk based food products are highly hygroscopic, due to high level of added or process converted sugars. Proper drying of these products is possible using modified design of three stage dryers, preferably having an air-broom system. In view of product quality and hygienic standards, spray-drying process is a potential future technology for drying malt-milk based food products to meet local as well as international requirements.