The technology of malting involves soaking of the grains, sprouting under high humidity conditions, drying and processing to remove the vegetative parts. Grain legumes and cereals are generally sprouted for preparing malted products. While green malt preparations are rich in enzymes used in the production of brewed alcoholic beverages, the kilned version is more commonly made for the food industry as a flavor ingredient in various foods like beverages, breakfast cereals, bakery goods etc. Barley is the most commonly used cereal since it has characteristic flavor and produces high levels of various enzymes on germination, ideal for getting good quality products. Some of the important enzymes produced during sprouting include alpha-amylase, beta-amylase, alpha-glucosidase, limit dextrinase, endopeptidase and endo-beta glucanase.
The malt desired for many applications is generally kilned at lower temperatures of about 60-65C while that demanded by distillers goes through a higher temperature of 85C. The pale malt has higher enzyme activity while dark malts contains only about 30% of the original enzyme activity. When malt is used for yeast fermentation, the sugars generated provide energy while the hydrolyzed protein products, as a result of the protease reaction, support yeast growth to produce alcohol. Beta glucanase enzyme modifies the insoluble polysaccharides into smaller molecular weight soluble components that helps to increase the viscosity very significantly. Beer products are valued for their color, flavor, bitterness derived from hops, viscosity and frothiness. Hard liquors like brandy and whiskey are made by distilling the alcohol produced during yeast fermentation and volatile constituents that come along with the alcohol give them their characteristic flavors
Manufacture of malt extract, an important flavor material for food industry is made from malted cereals. The combined malt amylolytic enzymes convert the insoluble starch present in the cereal into dextran and maltose while proteolytic enzymes hydrolyze proteins into peptides and amino acids. Aqueous extract so obtained is evaporated to get a viscous mass with about 78-80% solids. Spray drying yields malt extract powder or dry malt extract which will not contain any enzyme activity. In contrast dry malt obtained after sprouting, removal of sproutings, drying and coarse grinding under low temperature conditions, possess the characteristic enzyme activity so necessary for the liquor industry. Dextrin malt, caramel malt and black malt are made by heating to different extent and they have 53-63% reducing sugar, mainly maltose and 4.5 to 5.6% protein substances. Diastatic malt products like malt syrups have 60-72% reducing sugars and 1.8 to 3.5% proteins besides varying enzyme activities. Malt extract and syrups find use in more than 100 different food products including ice cream, baked goods like bread, biscuits and crackers, icings and fillings, malted milk and pastry.
As the malting operations involving several steps extending over at least 3-4 days for a batch to be completed, industry is severely handicapped in raising the productivity to meet the rising demand. The challenge is to make the process continuous and though technically it should be possible, the investment requirement will be astronomical while infrastructure requirement is mind-boggling. One of the alternate options available is to evolve a process that will use industrial enzymes commercially available to imitate the natural changes characteristic of natural malting. All enzymes identified as involved in malting like alpha and beta amylases, peptidases, beta glucanase and others are commercially produced by several internationally reputed biotech companies. Already some manufacturers of liquors have been able to reduce the barley needs for breweries by 70% using commercial enzymes and save considerably on time and cost. Biochemical engineers have studied the reaction kinetics of these enzymes and optimal working conditions are already well known. Continuous bio-reactors of different capacities with precise control of reaction conditions, are available to day and malt preparations of various specifications can be made continuously using them.