Coproduct recovery in dairy processing 1451 Whey

The principal by-product from dairy processing is whey from cheese and casein production, with 9 kg whey produced from each 1 kg cheese.

Moreover, cheese production has been increasing and this increase is predicted to continue into the next decade, thus utilisation of whey will continue to be a pressing issue for dairy processors. The high BOD5 of whey (40 000 mg/L) and of whey permeate (35 000 mg/L) presents a major pollution problem (Mawson 1994). The current estimates for transporting whey for disposal on to land or to animals are AUS$6000/ML (Zadow 2005), showing that costs are being borne by both the manufacturer and the environment when disposal is chosen as the method for dealing with whey. With increasing waste disposal penalties, alternative processes that add value to whey will become increasingly important.

Smaller factories often cannot justify the investment involved in manufacturing high-value, technologically challenging whey by-products. They seek cheaper alternatives with minimal processing or instead continue to spread whey on to fields and feed it to livestock. Very-large-scale cheese manufacturers produce enormous volumes of whey, therefore investment in large-scale process developments is more economically viable. Options for utilising whey from cheese and casein production include consideration of reuse within the factory with minimal processing or the development of new processes and co-products. Alternatively, joint ventures between several manufacturers create economies of scale enabling small-medium dairy processors to pursue more ambitious projects of co-product development.

Whey utilisation statistics

Early studies on dairy by-product utilisation show very low rates of whey utilisation. In 1968 an industrial waste profile of the United States dairy industry by the Federal Water Quality Administration found that the recovery of by-products from whey was only 53% compared with very high levels of by-product recovery for skim, buttermilk and cream (see Table 14.12). Overall this situation has shown some improvement with worldwide utilisation figures now estimated at 60% (Zadow 2005). Whey utilisation across the world is variable: North America, Oceania and Europe report high levels of utilisation, while South America reports lower levels of utilisation (see Tables 14.13 and 14.14).

Table 14.12 By-products from dairy wastes in the United States in 1968. Source: Gillies (1974)

Dairy by-product

Percent utilised

Conclusion

Skim from butter manufacturing

91

Efficient utilisation

Buttermilk from butter manufacturing

91

Efficient

Cream from cheese manufacturing

99

Efficient

Whey from cheese manufacturing

53

Improvement needed

Table 14.13 World annual whey balance and utilisation in 2001. Source: Zadow (2005)

OP a

Industrially

Demineralised

Table 14.13 World annual whey balance and utilisation in 2001. Source: Zadow (2005)

Industrially

Demineralised

Region

Total whey

utilised

WP and lactose

whey

WPC

(%)

(MT)

(%)*

(MT)

(%)f

(MT)

(%)f

(MT)

(%)f

(MT)

USA

24.8

36

80

28.8

50

14.4

10

2.9

40

11.5

EU

41.5

60

60

36

60

21.6

10

3.6

30

10.8

Canada

2.8

4

80

3.2

50

1.6

10

0.3

40

1.3

Argentina/Brazil

6.2

9

40

3.6

70

2.5

5

0.2

25

0.9

Australia/New Zealand

5.9

8.5

90

7.7

40

3.1

10

0.8

50

3.8

Rest of world

19.0

27.5

25

6.9

75

5.2

5

0.3

20

1.4

Total

100

145

59

86.1

56

48.3

9

8.1

34

* Percentage of total whey volume. f Percentage of whey utilised.

* Percentage of total whey volume. f Percentage of whey utilised.

Table 14.14 Utilisation of whey and permeate in Australia in the period 1991-2004. Source: Zadow (1992, 2000, 2005)

Dairy by-product

Year

1991

1999

2004

Whey production (ML)

1361

3022

3778

Whey utilisation (%)

50.4

62.2

87.8

Permeate production (ML)

118

746

1510

Permeate utilisation (%)

83.1

62.3

78.1

NB Whey utilisation does not include whey used as animal feed, or spread over land as fertiliser.

NB Whey utilisation does not include whey used as animal feed, or spread over land as fertiliser.

1400 1200 1000 800 600 400 200

1400 1200 1000 800 600 400 200

80 82 84 86 88 90 92 94 96 98 00 02 Year

Fig. 14.6 Production of dried whole whey and by-products, including demineralised whey (Demin), whey protein concentrate (WPC) and lactose between 1980 and 2002. Source: Zadow (2005).

- Dry whey Demin Lactose WPC

80 82 84 86 88 90 92 94 96 98 00 02 Year

Fig. 14.6 Production of dried whole whey and by-products, including demineralised whey (Demin), whey protein concentrate (WPC) and lactose between 1980 and 2002. Source: Zadow (2005).

Increasing whey utilisation reflects the growing awareness of the economic opportunities for high-value by-products from whey. Rather than producing only non-hygroscopic whey powder, larger amounts of whey are fractionated to produce whey protein concentrate and whey protein isolates (see Fig. 14.6). As whey protein production increases, the permeate fraction containing the bulk of the whey solids (lactose and minerals) is increasingly underutilised; some is used for milk standardisation and lactose manufacture but much is still being lost in the system, risking environmental problems.

Whey composition

Whey contains 95% of the original water, most of the lactose, 20% of the milk protein and traces of fat. The remaining milk solids, about 50%, are

Table 14.15 Composition of sweet and acid whey, and ultrafiltration (UF) permeate. Source: Durham (2000)

Composition

Sweet whey cheddar

Acid whey HCl Lactic

UF permeate cheddar

Solids (%)

6.6

5.1

6.0

5.5

pH

6.1

4.7

4.0

6.1

Lactose (%)

4.8

3.7

3.9

4.7

Protein (%)

0.9

0.73

0.72

0.01

Ash (%)

0.59

0.60

0.72

0.53

Lactic acid (%)

0.13

0

0.60

0

Fat (%)

0.06

0.05

0.003

0

Calcium (ppm)

430

1200

1140

375

Phosphorus (ppm)

440

680

900

275

Potassium (ppm)

1460

1200

1530

1450

Sodium (ppm)

430

270

400

430

Chloride ppm

970

2600

910

940

incorporated into cheese. The composition of whey depends upon the type of cheese produced. Factors such as the season, location, and type and health of dairy cattle also affect whey composition. There are two main types of whey: sweet whey and acid whey. Sweet whey (pH > 5.6) is produced from the manufacture of rennet cheese such as cheddar or mozzarella. Acid whey (pH < 5.1) is produced by lactic acid fermentation to produce fresh cheese such as cottage or cream cheese or by hydrochloric acid casein production. Acid whey contains higher levels of calcium phosphate compared with sweet whey, as shown in Table 14.15.

The mineral composition of sweet and acid whey is determined by the method of curd formation, either acid precipitation or rennet coagulation. Acid whey is formed as the pH is lowered and the colloidal calcium phosphate is solubilised, the casein micelle structure of milk is disrupted and the casein proteins aggregate releasing calcium phosphate into the whey (Brown 1988). Sweet whey is produced when rennin cleaves K-casein on the surface of the casein micelle, destabilising the casein complex, releasing casein-macropeptide into the whey, the remaining hydrophobic a, P paracasein flocculates together in the presence of calcium to form the cheese curd.

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