BY-PRODUCTS TECHNOLOGY

Module 3. Processing and utilization of whey

Lesson 23
PHYSICO-CHEMICAL PROPERTIES & UTILIZATION OF CONDENSED AND DRIED WHEY PRODUCTS

23.1 Introduction

Composition of condensed and dried whey vary depending on the type of whey from which they have been prepared, pretreatment given to the whey, and the various processing steps followed in the production. By far the single largest use of whey solids on global basis is in the form of whole dry whey and it continues to grow. This is whole whey that has been condensed and spray dried as such or after blending with certain other liquid ingredients. These powdered whey products are marketed as commodity ingredients for a variety of foods for human and animals. Whey solids in the form of concentrated whey or whey powder are used in different food industries. Whey powder is also used as an ingredient in animal feed mixes as well, since it is a cheap source of high-quality proteins and carbohydrates.

23.2 Physico-chemical Properties of Condensed and Dried Whey Products

23.2.1 Condensed whey

Chemical composition of plain, sweetened condensed whey and condensed acid whey is given in Table 23.1.

Table 23.1 Chemical composition of condensed whey

23.2.2 Whey powder

According to FSSAI (2011) Standards, whey powder means the product obtained by spray or roller drying sweet whey or acid whey, from which major portion of milk fat has been removed. It shall be of uniform colour with pleasant taste and flavour free from off flavour and rancidity. It may contain food additives permitted in these regulations. It shall conform to the microbiological requirements prescribed in Annexure - I. It shall conform to the requirements as given in Table 23.2. Other properties of whey powder are shown in Table 23.3.

Table 23.2 FSSAI (2011) compositional standards for whey powder

Table 23.3 Properties of whey powder

Whey powder easily accepts atmospheric moisture as a result of amorphous lactose content, proteins, and salts. Caking tendency is influenced by the degree of lactose crystallization, as well as the crystal number and size distribution. In ordinary whey powder, total lactose is in an amorphous form. Absorption of ambient moisture takes place until a balance with the powder moisture is achieved (e.g., approximately 30% moisture in the powder). Powder then loses its previous consistency and becomes viscous. The presence of moisture causes crystallization nuclei formation and lactose crystallization. As a result, vapor pressure of moist powder overcomes the pressure of the surrounding air, disturbing the balance and causing moisture desorption. The powder then undergoes solidification and can be used only as animal feed. In improved whey powders, where lactose precrystallization is implemented, these characteristics are much improved.

23.3 Utilization of Condensed and Dried Whey Products

Whey solids are used in dairy products, bakery goods, baby food, meat products, beverages, soups, sauces, dressings and creams. In addition, whey solids are used in animal feed mixes, as it is a cheap source of high-quality proteins and carbohydrate. Plain condensed whey and sweetened condensed whey may be used to make various whey candies such as 'wheyfers', whipped whey fudge, whey caramel and 'whey' taffy. The whipping properties of sweetened condensed whey is of value in many food preparations, say for example, ice cream, shakes, sherbets and bakery and confectionery products. Uses of whipped sweetened condensed whey include making of fruit whips, certain candies and frozen dessert preparations. A sweet spread of good keeping quality, may be made by mixing equal weights of sweetened condensed whey and peanut.

23.3.1 In dairy products

US Government regulations permit replacement of up to 25% of the MSNF of ice cream formulation with good quality sweet or acid whey solid in accordance with good manufacturing practices. In ice creams, whey powder can successfully replace skim milk powder and is less expensive. It has been proven that this substitution, ranging from 0-20%, does not influence the taste, consistency, or melting point of ice cream. The application of condensed and dried whey in other dairy products is significant as well. In Norway, "Mysost" and "Primost" cheeses are produced from concentrated whey with 84% total solids. Dulce de leche, yoghurt and whipped cream substitute may also contain condensed or dried whey.

23.3.2 In bakery products

Concentrated whey and whey powder have worldwide industrial application in bread and other bakery products. For example, condensed hydrolyzed whey added to flour during bread making enhances consistency and results in better structure, porosity, freshness retention, and taste of the final product, while improving the nutritive value. Liquid whey concentrate and whey powder are used in breakfast cereals, bakery and fried food products, where the development of a golden brown crust is desired. Whey powder is used at up to 3% of the flour in the formulation to improve crust colour, crumb structure and tenderness of bakery products. Special additives for the bakery industry are produced with whey powder as the main ingredient. In macaroni, spaghetti, and other production, added whey dry matter improves viscosity and dough properties.

23.3.3 In confectionery products

Condensed whey is used with fruits, jams in various toppings, and spreads in confectionery. Other uses include caramels, fudge & fondants where usage is from 8-16% of the sugar to reduce sweetness, prolong shelf life and improve nutritional quality. Condensed sweetened whey is used in caramel production, which is 38% whey solids, 38% sucrose and 24% water. Sweetened condensed whey is used as economical substitute for NFDM solids ingredient in candies and confections. Whey products provide important functions by increasing background milk flavour improving texture and chewiness & producing characteristic colour and flavour. High lactose concentration in the condensed whey enhances golden brown colour of caramel. In milk chocolates, although whey is not included as optional ingredient, but whey solids, particularly demineralized whey solids, provides several advantages for manufacturing chocolate milk products. Concentrated whey in chocolate liquor are used frequently and found compatible and increase flavour and bloom resistance in chocolate coatings.

A mixture of equal parts of peanut butter and sweetened condensed whey will produce an attractive sweet filling or candy center. It may also be used as a sweet spread. The addition of sweetened condensed whey takes the sticky, clinging characteristic from peanut butter and gives it a smooth, short type of body. The mixture is prepared by blending one pound of sweetened condensed whey for each pound of peanut butter to be treated.

23.3.4 In fermented products

Gandhi and Patel (1994) found that whey fermented with selected lactic acid bacteria could be concentrated up to 30% TS while retaining viable lactic acid bacteria at levels up to 10-30 cells/ml. The whey concentrate could be stored for up to 4 months at 5°C. Thus excess whey can be stored for up to 4 months in concentrated form and reconstituted as a fermented dairy beverage. Rodrignez et al. (2002) used concentrated whey and ultra filtered to get 3% true proteins. Thus was formed with yogurt cultures to get a fermented beverage.

23.3.5 Condensed whey as animal feed

Ruminants can consume as much as 30% of their dry matter requirement in the form of liquid whey. But pigs are limited to an amount of whey equivalent to 20% if their dry matter intake. The hydrolysis of lactose reportedly improved the nutritional value of whey and deproteinated whey for pigs and other animals that are more or less lactose intolerant. Whey solids can also be fed to dairy cows and other ruminants if proper conditions are maintained.

23.3.6 Miscellaneous uses of whey powder

There are other suggested uses for whey powder, such as ingredients in crèmes, pastes, or tablets for cosmetic baths, stabilizers in agricultural foams against frost, pesticide carriers, and polyurethane foam additives to slow down concrete solidification.

Selected reference

Gupta, V. K. 2007. Utilization of whey. Monograph of the IDA. Indian Dairy Association, New Delhi.