Module 2. Cereal processing

Lesson 10

MALTED MILK FOODS

10.1 Introduction

In the, Indian food market “Malted Milk Food” until recently, and “Malt Based Foods” at present are perhaps the only barley-based processed foods. Interestingly, this value-added food is most popular among children and therefore, it is no wonder these products represent among a rapidly growing milk-food market. Barley malt is major ingredient of malted milk foods and malt-based foods. Malted milk food is a product made by combining whole milk with the liquid separated from a mash of ground barley & wheat flour in such a manner as to secure full enzymic action of the malt extract, and reducing the mixture to dryness by desiccation. It may also contain added sodium chloride, sodium / potassium bicarbonate. India is among the world’s biggest market for malt- milk based food products. Malted- milk food products’ market in India has been growing in the range of 5 to 8 per cent for the last ten years.

10.2 Historical Background

Malted milk food was developed in 1883 by William Horlicks of Racine, Wisconsin, and the product was commercially marketed in 1887. William Horlicks who undertook the research at the request of some physicians for developing a baby food containing milk solids and cereal solids. This product received the attention of the medical professionals and the consumers due to its convenience, nutritive value, digestibility and palatability.

10.3.1 FSSA definition

10.3.1.1 Malted milk food

According to FSSA (Food Standard Safety Act) malted milk food means the product obtained by mixing whole milk, partly skimmed milk or milk powder with the wort separated from a mash of ground barley malt, any other malted cereal grain and wheat flour or any other cereal flour or malt extract with or without addition of flavouring agents and spices, emulsifying agent, eggs, protein isolates, edible common salt, sodium or potassium bicarbonate, minerals and vitamins and without added sugar in such a manner as to secure complete hydrolysis of starchy material and prepared in a powder or granule or flake formed by roller drying, spray drying, vacuum drying or by any other process. It may contain cocoa powder. It shall be free from dirt and other extraneous matter. It shall not contain any added starch (except natural starch present in cocoa powder) and added non milk fat. It shall not contain any preservative or added colour. Malted milk food containing cocoa powder may contain added sugar. Malted milk food shall also conform to standards (Table 10.1).

10.3.1.2 Malt based food (Malt food)

Acording to FSSA (Food Standard Safety Act) malt based food (malt food) means the product obtained by mixing malt (wort or flour or malt extract) of any kind obtained by controlled germination of seeds (cereals and/or grain legumes), involving mainly steeping, germination and kiln drying processes with other cereal and legume flour with or without whole milk or milk powder, flavouring agents, spices, emulsifying agents, eggs, egg powder, protein isolates, protein hydrolysates, edible common salt, liquid glucose sodium or potassium bicarbonate, minerals, amino acids and vitamins. It may contain added sugar and / or cocoa powder and processed in such a manner to secure partial or complete hydrolysis of starchy material in the form of powder or granules or flakes by drying or by dry mixing of the ingredients. The grain legume and their products used in the preparation of malt shall be sound and uninfested and free from insect fragment, rat excreta, fungal infested grains or any other type of insect or fungal damage. It shall also conform to standards (Table 10.1).

10.3.2 BIS standard

India Standard Institution (ISI) have also prescribed specification (IS 1806: 1975) for malted milk (Table 10.1).

Table 10.1 FSSA and BIS requirements for malted milk food and malt-based foods

Characteristics	FSSA Requirements			BIS Requirement
Characteristics	*Malted milk food without cocoa powder*	*Malted milk food with cocoa powder*	*Malt-based foods* *(Malt food)*	*Type I*	*Type II*
Moisture	≤ 5.0 % by wt.	≤ 5.0 % by wt.	≤ 5.0 % by wt.	≤ 4.0 % by wt.	≤ 4.0% by wt.
Total protein (N x 6.25) (on dry basis)	≥ 12.5 % by wt.	≥ 11.25 % by wt.	≥ 7.0 % by wt.	≥ 13.0% by wt	≥ 11.5% by wt
Total fat (on dry basis)	≥ 7.5 % by wt.	≥ 6.0 % by wt.	-	≥ 7.5% by wt.	≥ 6.0% by wt.
Total ash (on dry basis)	≤ 5.0 % by wt.	≤ 5.0 % by wt.	≤ 5.0 % by wt.	≤ 5.0 % by wt.	≤ 5.0 % by wt.
Acid insoluble ash (on dry basis) (in dilute HCl)	≤ 0.1 % by wt.	≤ 0.1 % by wt.	≤ 0.1 % by wt.	≤ 0.1 % by wt.	≤ 0.1 % by wt.
Solubility	≥ 85 % by wt.	≥ 85% by wt.	-	≥ 85% by wt	≥ 80% by wt
Cocoa powder (on dry basis )	-	≥ 5.0 % by wt.	-	-	≥ 5.0% by wt
Test for starch	Negative	-	-	Negative	Negative
Alcoholic acidity (expressed as H₂SO₄) with 90 % alcohol on dry wt. basis	-	-	≤ 0.3 %	-	-
Bacterial count	≤ 50,000/g	≤ 50,000/g	≤ 50,000/g	≤ 50,000/g	≤ 50,000/g
Coliform count	≤ 10/g	≤ 10/g	≤ 10/g	≤ 10/g	≤ 10/g
Yeast and mould count	Absent in 0.1 g	Absent in 0.1 g	≤ 100/g	-	-
Salmonella and Shigella	Absent in 0.1 g	Absent in 0.1 g	Absent in 25 g	-	-
E.coli	Absent in 0.1 g	Absent in 0.1 g	Absent in 10 g	-	-
Vibrio cholera and V .paraheamolyticus	Absent in 0.1 g	Absent in 0.1 g	Absent in 0.1 g	-	-
Fecal streptococci and Staphylococcus aureas	Absent in 0.1 g	Absent in 0.1 g	Absent in 0.1 g	-	-

Type I: Malted milk foods containing no cocoa powder, Type II: Malted milk foods containing cocoa powder

10.4 Ingredients Used in Manufacture of Malted Milk Foods

Various ingredients are used in the manufacturing of malted milk foods. Newer formulations and manufacturing processes are developed to meet customers requirements for a quality product. Main ingredients and their functions, used in manufacturing of malted milk foods are described in Table 10.2.

Table 10.2 Ingredients used in manufacture of malted milk foods

Ingredient	Function
Wheat flour or any other source of starch	All the starch is fully converted to simple sugars during the mashing process and provides higher levels of simple sugars, proteins, and fat
Malted barley or Malted wheat	Provides an appropriate level of enzymes required to convert all the starch into simple sugars and also imparts typical malty flavour to the finished product
Malt extract	Provides desirable levels of colour and typical caramelized flavour
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
Salts	Salts are added to optimize product pH to improve digestibility, enhances flavour, and to provide essential micronutrients, specially calcium
Microingredients	Improves nutritional value of the product and provide essential requirement of minerals and vitamins

10.5 Method of Manufacture of Malted Food

The preparation of malted milk combines the technique of dried milk manufacture with that of the brewing. The process consists of mixing milk solids with the liquid resulting from the mashing of barley malt, and wheat flour with certain minor ingredients. Hunziker in 1949 suggested a method for preparation of dried malted milk. The crushed malt after steeping at 90°F should be mixed with cooked (at 200°F/2 h) wheat flour slurry in ratio of 0.4 pounds of wheat flour per pound of malt. Mashing should be done by holding malt- flour mixture at 113°F/30 min and then the temperature be raised gradually to 158°F and holding at this temperature for 2 h to complete the conversion of starch to sugar. After separation of the wort, milk should be mixed to have minimum statutory requirements of 7.5% fat. The mixture, after forewarming (at 150°F) and condensing (68-70% total solids) can be dried in a special vacuum pan or in drum drier or in a spray drier.

Sanyal (1980) prepared spray dried malted milk by using barley malt and wheat flour. Crushed barley malt and wheat flour (1.5:1) were steeped in 5-6 times of water of its total weight. The mashing process was performed under the following temperature-time regime; 32°±1°C for 30 min, 45°C for 15 min, 60°-70°C for 100 min, and 78°-80°C for 10 min, for the purpose of steeping, proteolysis, complete starch hydrolysis, and inactivation of enzymes, respectively. The mashing process was followed by filtration and washing of the husks with warm water. To this wort, standardized milk having 2% fat was added to have final product containing 7.5- 8.0% milk fat. The pH of the mix was adjusted to 7.0 with sodium bicarbonate. The mix was then forewarmed to 80°C for 15 min and then condensed to 30 and 40 per cent total solids in double effect evaporator. The mix was then spray dried at 190°±10°C and 95°±5°C, inlet and outlet air temperatures, respectively; with 25000 rpm speed of an atomizer.

Banerjee (1982) manufactured spray and roller dried malted milk using malt extract. Malted milk mix was prepared by mixing required quantities of malt extract, cream, concentrated skim milk and water. For the manufacture of spray dried malted milk, the ratio of malt solids to milk solids was 40:60, whereas for the roller dried malted milk the different ratio of malt solids to milk solids were tried, viz., 30:70, 20:80, 15:85,10:90, 7.5:92.5. The pH of the mix was adjusted to 6.8 to 7.0 with solution of sodium bicarbonate. The mix was then heated to 65°C and homogenized at a pressure of 2000 psi in the first stage and 500 psi in the second stage. The homogenized mix was heated to 85°C for 1 min before drying. The malted milk mix having 35, 40, and 45% total solids was spray dried at 200°±5°C inlet air temperature and 80°± 2°C outlet air temperature with speed of atomizer 20000 rpm. The roller drying of the malted milk mix was done at a steam pressure ranging from 65 to 70 psi and roller speed of 20 rpm.

Salooja (1983) obtained spray dried malted milk food by preparing wort through steeping of grains, mashing and filtration of spent grains. The mashing conditions were optimized for wheat flour and crushed barley malt in the ratio of 1:4 in 4-5 times its weight of water. Steeping of grist was performed at 35°C for 30 min with constant agitation. Mashing followed temperature-time regime of 45°C for 30 min (Protein hydrolysis), 55°C for 30 min (1^st stage starch hydrolysis), 60°C for 60 min (2^nd stage starch hydrolysis), 68°C for 60 min (complete starch hydrolysis). Inactivation of enzyme was carried out by heating the mashed mixture to 80°C for 10 min. Spent grains were then separated by filtration. The pH of the wort was adjusted to around 7.0 by the addition of sodium bicarbonate. Standardized milk was mixed with wort so as to have in the final product a fat content of not less than 7.5 per cent and protein not less than 13 per cent. The mixture of milk and barley malt wort was pre-heated to 85°C for 10 min and the mixture was then concentrated to 45 per cent total solids in vacuum pan. The concentrated product was spray dried at 25000 rpm speed of an atomizer, 195°±5°C inlet air temperature and 90°±2°C outlet air temperature. The spray dried product was packed and stored at 30°±2°C.

Cereal extract of malted barley and wheat flour is prepared by either batch or continuous method. Malted barley is sieved to remove dust and other foreign matter. It is then crushed using line roller mill and mixed with wheat flour. The mix is conveyed to mash tank, where water at 40°C is continuously added to prepare uniform slurry. The slurry is gradually heated to raise the temperature from 40°C to 70°C within about 40 min. The slurry is held at 70°C for about 35 min for complete the conversion of starch into maltose and dextrose. 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 slurry is then filtered to separate barley husk and obtain clear liquid, known as “wort”. The wort is then mixed with pre-determined quantities of milk, malt extract, sugar, salt, minerals and vitamins. The with about 26% solids is concentrated under vacuum, either in single stage calandria (50-58% solids) or in multiple stage evaporators (80% solids). The concentrate is then dried by using vacuum oven drying, band drying or spray drying.