BY-PRODUCTS TECHNOLOGY

Module 3. Processing and utilization of whey

Lesson 38
APPLICATIONS OF HYDROLYSED LACTOSE

38.1 Introduction

To be commercially viable, lactose-hydrolysed products must offer the food manufacturer commercial advantages over competitive products. These advantages must either provide direct benefits to the consumer (such as the ability to be tolerated by lactose malabsorbers) or commercial benefits to the manufacturer (with functional or economic advantages bestowed on the product through the incorporation of lactose-hydrolysed products). Clearly the major benefits of hydrolysed whey and permeate relate to their ability to replace costly sucrose.

38.2 Applications of Lactose Hydrolysed Whey

Lactose hydrolysed whey can be utilized in various products including ice cream.

38.2.1 Confectionery

Partially demineralized lactose hydrolysed whey syrup can easily replace skimmed sweetened condensed milk (well known ingredient in the manufacture of caramels) because of their very similar composition, when compared (Table 38.1). Lactose hydrolysed whey syrups can replace 100% of the condensed milk in an enrobed fudges and caramel and is deposited soft caramel in chocolate shells (for toffee and hard caramel modification of the recipe is done). The benefits of hydrolysed lactose for the replacement of sweetened condensed milk in caramels are: an increase in chewiness due to the presence of whey proteins, reduced crystallization of lactose due to the inhibiting effect of the glucose and galactose, and a darker colour and improved flavour.

Hydrolysed permeate (or lactose) syrups may be regarded as equivalent to a 63 D.E. glucose syrup and as such may be substituted in recipes employing glucose syrup. e.g.

Pectin jellies: 100% replacement of glucose syrup entirely satisfactory.
Fudge: 50% replacement of glucose syrup entirely satisfactory
Fondant creams: 50% replacement of glucose syrup satisfactory but off flavour development occurred with prolonged storage.
Boiled sweets: 50% replacement of glucose syrup unsatisfactory because of rapid coloration during boiling.

Table 38.1 Comparison of Partially demineralised hydrolysed whey syrup with skimmed sweetened condensed milk

Lactose hydrolysed whey, without or with partial demineralization or in a dried form, is used in chewing gum to at least partially replace the soluble sweetener, emulsifier and plasticizer components of conventional formulations. The inclusion of hydrolysed whey results in a softer gum which is not sticky. It is also advantageous in an athlete’s gum which promotes salivation. There are also cost benefits.

38.2.2 Ice cream and mousse

The incorporation of hydrolysed lactose into ice cream would replace the di- and polysaccharides in the mix by monosaccharides which will result in an ice cream which has a lower freezing point and produce a somewhat softer texture, which may be considered as a market advantage for certain application. It is possible to produce a “soft scoop” ice cream without the use of a freezing point depressant such as glycerol. The mix that scored the highest in creaminess, smoothness and fullness of flavor contained 15% SNF, supplied by a 1:1 blend of skim milk and whey protein concentrate, and 75% hydrolyzed lactose syrup.

The potential for incorporation of hydrolysed products into ice creams will depends to some extent on the particular legislation controlling minimum ice cream composition within a particular country. When using hydrolysed whey, it will also be necessary to re-balance the sugar composition in order to maintain a similar sweetness level as the original. In general, the use of hydrolysed milks to replace added sucrose results in decreasing the total solids of the product. In some cases the reduced level of solids may be below that required by legislation, thereby negating the benefits of using hydrolysed products.

38.2.3 Whey drinks

In whey beverages, hydrolysis of lactose avoids problems of proteins precipitation as well as lactose intolerance. Whey drinks as a mixture of tropical fruit juices, hydrolysed lactose and whey protein concentrate have been prepared. These drinks use the sweetening power of the glucose and galactose but at the same time gain the advantage of having the presence of whey proteins, which have a high nutritional value. A range of similar products may be produced using different fruit juices such as orange, lemon, apple, etc.

38.2.4 Bakery

Hydrolysed whey syrup can be used to replace up to 30% of the egg (on solids basis) in Sponge cake and Madeira cake according to recipes published by Specialist Dairy Ingredients. Hydrolysed whey syrup could also be used to replace a part of the milk powder in the recipes. It is suggested that up to 50% replacement could be achieved.

Lactose hydrolysed whey can lead to faster dough development and higher loaf volume, porosity and crumb compressibility, all due to more readily fermentable sugar. Browning in baked products is also enhanced due to presence of the highly reactive galactose. Use of hydrolyzed lactose syrup (50, 75, 95%) from whey permeate as sugar substitute in milk bread formulation with or without demineralization were decolorized and concentrated to 50 per cent solids to give hydrolyzed lactose syrup (HLS). These were added to bread mix at 6% of the flour content. Bread made from 95% HLS (demineralized) was comparable with control bread pH, volume, texture and flavour.

The high content of sugars which are readily fermentable by yeast and can take part in melanoidin reactions makes the syrup suitable for use as sweetener in the bakery industry. Addition of 3.9-4.1 percent lactose syrup significantly improved the physio-chemical and organoleptic properties of wheat bread. They yielded even better results in thin and thick dough sponges. Hydrolysed lactose whey is also used in the manufacture of biscuits.

38.2.5 Jams

Hydrolysed permeate syrups has been used to replace up to 50% of the glucose syrup in jam manufacture. The products were satisfactory but whilst full decoloration of the syrup was not required, it was necessary to minimize the mineral level in the syrup.

38.2.6 Meat products

Extenders for fermented sausage products incorporating lactose-hydrolysed whey or permeate have been described. As extenders, lactose-hydrolysed products are equivalent to, but less expensive than products such as skim milk powder. The suggested level of incorporation is 3.5% of the mix, with 70% of the lactose hydrolysed. The use of hydrolysed whey products in comminuted meats has also described.

38.2.7 Animal feeds

Both hydrolysed permeate and hydrolysed whey have been employed in animal feeds. Work carried out in Finland on pig feeding indicated a higher efficiency of utilization in comparison to ordinary whey.

39.2.8 Other Uses

A wide variety of different other products have been suggested when hydrolysed whey or permeate could be used. Some of these are given in Table 38.2.

Table 38.2 Other uses for hydrolysed whey and lactose (or permeate)

Selected references

Ryder, D.N. 1988. Hydrolysis of lactose in whey products. Bulletin of IDF Document 233: 45-52.
Kanwajia, S.K. and Sukhbir S. Singh 1992. Application of hydrolysed lactose whey in food processing. Indian Dairyman, 44 (12): 600-603.