BY-PRODUCTS TECHNOLOGY

Module 1. Introduction

Lesson 2
GLOBAL STATUS, AVAILABILITY AND UTILIZATION OF DAIRY BY-PRODUCTS

2.1 Introduction

In recent years, there has been wide spread and increasing interest throughout the world in creating newer channels for the utilization of by-products of the dairy industry. The production of by-products like casein, caseinates, co-precipitates, protein hydrolysates, whey protein concentrates, lactose, whey beverages, low lactose powder and many others have prominence in advanced dairy countries. The western dairy industry especially American and European and also of Australia and New Zealand have been the harbingers in the utilisation of by-products. They have developed technologies for the utilisation of by-products, developed large automated plants and also developed users for by-products in dairy and food industry. A large range of milk protein products is presently recovered from milk. It is likely that this range will be extended in the future as methods developed to effect separation of individual caseins and whey proteins become commercial. The main area of application of milk protein products will continue to be as functional ingredients in formulated foods, it is likely that there will be increased use of milk protein-based products in dietary, pharmaceutical and medical products.

2.2 Skim Milk and Its By-Products

The way in which the skimmed milk is utilized has changed dramatically. Firstly the proportion of supplies used for direct feeding to livestock has declined from over 50% in 1960 to only 11% in 1979. More of it was used for the manufacture of skim milk powder (which was the main way of utilization of skim milk from 14% in 1960 to 53% in 1979). Presently, skim milk is mostly utilized either in standardization of milk for the manufacture of main dairy products or preserved by removing moisture in spray dried form. The skim milk when utilized in either of these two forms or consumed as liquid is not considered a by-product. It is regarded as a by-product, only when it is either not economically utilized or has to be utilized for the manufacture of derived by-products like casein in small quantities. In 2002, about 6 million tonne of skim milk was utilized for casein production.

2.2.1 Casein and caseinates

Estimated production of casein was 3.5-4.3 lakh tonnes in 2005 (Fig.2.1). The large producers of casein are New Zealand, Netherlands and Germany. The world market of casein/caseinates used in the food industry fluctuates between 2 to 2.5 lakh tonnes. The biggest importer of casein is United States of America, where food casein demand can be estimated at 20,000 tonnes per year and caseinates demand at 27,000 tonnes per year. About 20% of this demand is for nutraceutical applications. The second biggest importer is Japan. A lot of casein is utilized for the manufacture of imitation cheeses. Total export of casein and caseinates from New Zealand reached 1.34 lakh tonnes in 2004.

Fig. 2.1 World casein production-2005

2.2.2 Co-precipitates

The manufacture of co-precipitates has several advantages like increased yield and higher nutritional value over that of casein. However, it has never been commercially exploited to any great extent.

2.2.3 Milk protein hydrolysates

Today protein hydrolysis has assumed a new dimension in the food industry. Milk protein hydrolysates find extensive use in nutritional, dietetic and formulated foods, where a pre-digested form of protein is needed.

2.3 Whey and its By-Products

Whey is the largest by-product of dairy world. In 2008, Global production of liquid whey from cheese and casein was estimated at about 186 million MT. The EU and US produce about 70% of whey in the world. Cheese whey accounts for nearly 95% of total whey. The continuing annual growth in the production and consumption of cheese and coagulated milk products represents the generation of about two percent additional quantities of whey globally every year. Whey trade has grown from approx. 860,000 MT in 2005 to more than 1,010,000 MT in 2008, corresponding to an annual growth of 5-6%, US and EU accounting for approx. 80% of global whey trade followed by China and Canada (Fig.2.2). In Rest of world, the Asian countries represent a major market. Some South American countries, Mexico and Russia are clearly emerging markets. In 2008, large export of whey was from west to east. In the East, Japan, Korea, Thailand and Indonesia are major whey importers.

The processing options for whey utilization fall into four main areas

• Those concerned with simple removal of water (spray or roller drying to yield whey powder).
• Those concerned with increasing the ratio of protein in the end product (ultra filtration for manufacture of whey protein concentrates, fractionation processes for the manufacture of protein isolates, heat treatment for the production of lactalbumin).
• Those concerned with utilization of lactose in whey (treatment with lactase or heat/acid for lactose-hydrolyzed products, fermentation to a number of products such as lactic acid, citric acid and microbial biomass proteins).
• Those designed to alter the mineral composition of the product (electrodialysis and ion-exchange for the manufacture of demineralised products).

Whey proteins and lactose are clearly mainstream ingredients. Many of the whey protein fractions and lactose derivatives are still at a very early market development stage.

Fig. 2.2 Global overview of major whey markets

Today, modern industrial processing techniques such as membrane processing, new drying methods, hydrolysis, electrodialysis, ion-exchange, fermentation and protein fractionation, among others, have converted whey into a major source of numerous ingredients with differing functional and nutritional properties finding increasing utilization in various branches of the food and dairy industry. Membrane processes are continuous molecular separation processes that do not involve either a phase change or inter-phase mass transfer. Therefore, energy requirements of membrane processes are very low compared with other processes such as evaporation, Further, easy, simple and economical operation, improved recovery of constituents and better yield of products are other advantages for which membrane processes are valued. A membrane separation system separates an influent stream into two effluent streams known as the permeate and the concentrate. The permeate is the portion of the fluid that has passed through the semi-permeable membrane. Whereas the concentrate stream contains the constituents that have been rejected by the membrane.

The main membrane systems in ascending order of pore size are: reverse osmosis (RO), nonofiltration (NF), ultrafiltration (UF) and microfiltration (MF). In a broader sense RO is essentially a dewatering technique, NF a demineralization process, UF a method for fractionation and MF a clarification process. The principal application of nanofiltration is for separation of mineral ions in the 10^-9 m size exclusion range. UF membranes retain only macromolecules or particles larger than 1-20 nanometers. This process typically employs membranes with molecular cut-of in the range of 10000 - 75000 D. MF processes are designed to separate particles in the so called micrometer range, that is suspended particles of 0.1-10 micrometers.

The predominant driving force behind the development of whey utilization has been stringent regulations imposed by the environmental pollution agencies all over the world. Other aspect relates to economic return from whey, which contains almost half the solids of original milk. Table 2.1 gives the production of major whey products. The market for whey products is estimated to be about $ 6.5 billion in sales globally. During the last few years, many new products have been launched including bakery, confectionery, dessert, ice creams, snacks etc. The number of new products launched has grown, on average, approx. 15% per annum from 2002-2008. In 2008, out of top five countries (USA, UK, Japan, Brazil and Germany), USA was the number one producer of whey products.

Table 2.1 Production of whey and modified whey products in the United States in 2005 (USDA)

2.3.1 Condensed and dried whey

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 food and animal applications. The feed industry may be the largest consumer of dried whey and whey products.

Considerable advancements have been made in condensing and drying equipments for energy conservation and for the production of better quality product. A significant trend in the last two decades has been the increasing interest in RO for removing water from whey. Small plants concentrate whey by RO for shipment to the larger plants. Medium sized plants concentrate whey by evaporation for large drying plants. Large plants concentrate their own whey plus outside sources whey to high solids for lactose crystallization and drying.

During 1990-2000, four countries accounted for more than 80% of world dry whey production. United States was the largest dry whey producer, with an average share of more than 31% of annual world dry whey production. France followed with an average share of 28%. Netherlands averaged a 15% share, and Germany averaged slightly less than 10% of the world production. EU accounted for more than 60% of world dry whey production. Combined, United States and EU accounted for more than 90% of world dry whey production.

Global exports of dried whey are dominated by the EU and United states, which together accounted for approximately 64% of world export in 2002. Australia ranked third among leading dry-whey exporting countries with 66,000 MT, or 11 percent of the world exports. Dry whey is imported in several countries, most of which are developing countries. China ranked as the world’s leading importing country of dry whey, importing 138,000 MT in 2002, accounting for 25 % of global imports.

2.3.2 Demineralised whey

At the other end of the spectrum, a small percentage of utilized whey (less than 5%) is demineralised by ion exchange or electrodialysis prior to spray drying to produce dry demineralised whey for specialized uses including whey protein based infant formulas and other medical and nutritional products that require lactose, special nutritional quality of whey proteins and low mineral content.

2.3.3 Whey drinks

Liquid whey has been utilized for the manufacture of wide range of beverages and soups over the years, as a result of which a number of such products are available to consumers. The utilization of whey into various vegetable based soups and fruit beverages is one of the most attractive avenues for the utilization of whey. Cheese whey has successfully been tried in the manufacture of mixed vegetable, mushroom, tomato and spinach soups, whereas, paneer whey is suited for mango, lemon, banana and pineapple beverages.

Commercial interest in fermented whey beverages has increased in several European countries notable Germany, Holland, Australia and Switzerland, possibly as a result of health consciousness of the modern consumers. Alcoholic whey beverages are available in certain local markets. Products like whey beer and whey wine appear to be of limited importance.

2.3.4 Lactose production

The production of lactose from whey continues to be one of the most important forms of whey’s utilisation. The global market for lactose based goods is valued at over $ 3 billion. Europe is the largest producer of lactose followed by United States. In 2006, the production of lactose was 850,000 MT in Europe and 317,000 MT in United States. In 2008, the global lactose market was worth roughly US $ 1.5 billion. During 2005-2008, market volume for lactose increased up to 8% and its market value up to 25%. Total market volume for lactose products was approx. 1,652,000 MT globally in 2008.

2.3.5 Whey protein concentrates

New Zealand is the largest manufacturer of WPC by ultrafiltration (UF) process in the world. By UF process, a highly functional WPC is produced as the primary end product for a wide variety of applications as a substitute for non-fat dry milk and other protein ingredients. The estimated production of WPC, WPI and WPH in 2010 is given in Fig. 2.3.

The global whey protein market was worth roughly US $ 3.8 billion in 2008. During 2005-2008, market volume of whey protein increased up to 3% and market value up to 24% (Fig. 2.4). Food consumption of whey proteins, WPC and WPI was estimated approx. 190,000 MT, 85,000 MT and 14,500 MT respectively. Whey protein fractions such as lactoferrin, α-lactalbumin and colostrum/IgG alongside galacto-oligosaccharides (GOS) are showing interesting new application opportunities and significant annual growth rates. For instance GOS is growing annually by an impressive 15 per cent.

Fig. 2.4 Global whey protein market in 2008
(Source: 3A Business Consulting)

2.3.6 Fermented products

The lactose in whey can be converted by fermentation by a variety of organisms to products ranging from lactic acid to flavouring materials, but the identification of the most cost effective means for its utilization is still awaited by most dairy companies world wide. Up to some extent, alcohol is produced from the fermentation of lactose. Three plants in New Zealand are in operation presently producing alcohol cost effectively by the fermentation of lactose.

2.4 Buttermilk

The worldwide production of buttermilk could be considered close to that of butter production, which was estimated at around 8.6 million tonnes in 2006. In the United States, the commercial use of buttermilk was mainly for the baking industry (39%), prepared dry mixes (33%), and for the dairy industry (23%) during 2002.

2.5 Butter Oil/Ghee-Residue

Butter oil/ ghee-residue is not generally used anywhere in the world. A sincere R & D work and a strong willingness on the part of manufacturer is required to develop food uses of butter oil/ ghee-residue and put it in the market place.

Selected references

Chandan, R.C., Kilara, A. and Shah, P.N 2008. Whey and whey products. In: Dairy processing and quality assurance, 15: 337.
Prasad, V. 2007. Whey processing. In: Dairy India-sixth edition, ed. P.R. Gupta and Sharad Gupta, Dairy India Yearbook: 244.
Vanderghem C., Bodson P., Danthine S., Blecker, C., Paquot, M. 2010. Milk fat globule membrane and buttermilks: from composition to valorization. Biotechnol. Agron. Soc. Environ., 14 (3): 485-500.