Utilisation of whole whey

Whey is highly perishable and needs to be collected hygienically and utilised soon after manufacture. Whey is first clarified to remove cheese solids and pasteurised to stop starter culture activity. If these steps are taken, the whey can be used as food in a wide range of products, with the dairy manufacturer's choice determined by scale, availability of equipment and markets for the products. Most of the costs associated with processing whey arise from evaporation and drying due to the low solids levels in fresh whey. Liquid applications are less capital intensive but require rapid, flexible production capabilities able to deal with the variable quantities of whey available throughout the day in the cheese factory. Options for processing whey have been summarised in Figure 14.7.

Whey drinks

Whey drinks are an attractive option for small-scale cheese makers, utilising equipment generally available in most dairies. Early reports of whey drinks describe the formulation of fresh pasteurized fruit flavoured whey drinks and lactic-fermented whey drinks (Jelen et al. 1987; Schwab 1995). However, these have not been taken up commercially on a significant scale. A widely accepted whey drink in Switzerland, Rivella, is marketed as a de-proteinated carbonated drink, but is not identified as a whey drink (Sciancalepore et al. 1992; Johnson et al. 1996). Opportunities continue to exist to market the nutritional advantages of whey in a refreshing drink. Anji and Durham (2005) report development of a nutritious, flavoursome, pineapple and mango whey drink based on ultrafiltered, fresh sweet cheese whey. The drink was given a 90 °C/4 s heat treatment for a refrigerated extended shelf-life (ESL).

Cheese whey can also be incorporated into many of the fresh products currently produced in the dairy factory. Studies by Nguyen et al. (1997) demonstrated that small dairy manufacturers can employ membrane concentration to recover cottage cheese whey for use in ice cream or yoghurt, with a payback period of less than 10 months.

Whey in dairy product standardisation

An increasingly significant application of milk and whey permeate is milk protein standardisation (Jelen & Michel 1999; Nissen 1999). The standardisation of the protein content of milk was approved by the Codex Alimentarius Commission in July 1999 (Heggum 1999). Milk protein standardisation studies by Rattray and Jelen (1996) showed that skim milk permeate and sweet whey permeate increased the freezing point of milk due to the lower lactose levels, while acid casein whey permeate had the opposite effect. It was suggested that using combinations of permeates or addition of lactose may help to achieve the desired solids levels. It was also noted that permeates from lactic acid fermentations were unsuitable due to the presence of starter culture metabolites, which affected the flavour and storage stability of the milk.

Whey fermentation

There are a multitude of whey fermentation by-products that utilise the nutrient-rich liquid whey (see Table 14.16). The attributes required for commercialisation are exacting. Commercially successful whey fermentations include processes for the production of cheese starter cultures,

Evap/drying Ion exchange, nanofiltration, or electrodialysis

Evap/drying Fermentation

Whey

Ultrafiltration

UF permeate

Lactose crystallisation

Whey protein concentrate

Evap/drying r

Dried whey Demineralised whey

Alcohol and chemicals

Derivatisation i

Lactulose, lactitol, etc.

Hydrolysis i

Hydrolysed lactose i

Purification i

Pharma Whey lactose protein concentrate

Ion exchange purification

Precipitation/ Ion exchange separation

Ion exchange and membrane fractionation

Hydrolysis and fractionation

Whey protein isolate a-lactalbumin ß-lactoglobulin

Lactoferrin, glycomacopeptide, lactoperoxidase

Bioactive peptides

Fig. 14.7 Process alternatives for creating by-products from whey.

a ry

i ry

LO Ul Ul

Table 14.16 Fermentation by-products from whey produced from a range of bacterial and yeast fermentations

Product

Organism

Reference

Ethanol

Butanol/acetone Acetate

Galactitol

Glycerol Lactic acid

Citric acid Vinegar

Propionic and acetic acid

Gluconic acid Succinic acid

Diacetyl

Nisin

Single cell protein Exop olys acch aride

Saccharomyces cerevisiae (immobilised ß-galacto-sidase), Kluveromyces fragilis, Candida pseudotropicalis Recombined Saccharomyces cerevisiae (genes from K. marxianus) Clostridium acetobutylicum Lactococcus lactis/Clostridium formicoaceticum Lactobacillus helveticus/ Gluconobacter oxydans

Aspergillus niger/

Mycobacterium smegmatis

Kluveromyces marxianus

Lactobacillus salivarius Lactobacillus lactis Lactobacillus casei Lactobacillus helveticus Lactobacillus delbrueckii Aspergillus niger Kluveromyces fragilis/ Acetobacter pasteurianus

Lactobacillus helveticus/ Propionibacterium acidipropionici Propionibacterium jensenii Propionibacterium acidipropionici Aspergillus niger

Anaerobiospirillum succiniproducins

Lactococcus lactis subsp.

lactis diacetylactis Lactococcus lactis

Kluveromyces fragilis Schizosaccharomyces pombe (mutant strain)

Streptococcus thermophilus Streptococcus thermophilus Lactobacillus delbrueckii subsp. bulgaricas Pseudomonas elodea

Lewandowska et al. 2002

Domingues et al. 2001

Haddadin et al. 1997 Huang & Yang 1998

Poget et al. 1994 Muniruzzaman et al. 1994

Rapin et al. 1994

Vasala et al. 2005 Liu et al. 2004 Buyukkileci & Harsa 2004 Fitzpatrick & O'Keeffe 2001 Gassem & Abu-Tarboush 2000 El-Samragy et al. 1996 Parrondo et al. 2003

Haddadin et al. 1996

Tuckett et al. 1996 Sorlini & Daffonchio 1995

Mukhopadhyay et al. 2005 Lee et al. 2000

Gutierrez et al. 1997

Hickmann & Monte

Alegre 2001 Ghaly et al. 2005 Abou-Zeid & Zaied 1999

Vaningelgem et al. 2004 Zisu & Shah 2003 Briczinski & Roberts 2002

Dlamini & Peiris 1996

Table 14.16 cont'd

Product

Organism

Reference

Lactan

Rahnella aquatilis

Pintado et al. 1999

Xanthan gum

Xanthomonas campestris

Nitschke et al. 2001

Bacterial slime

Lactococcus lactis

Christiansen et al. 2001

Biosurfactant

Pseudomonas aeruginosa

Dubey & Juwarkar 2004

Lipids

Apiotrichum curatum, Cryptococcus albidus, Lipomyces starkeyi

Akhtar et al. 1998

P-Galactosidase

Kluveromyces marxianus

Santiago et al. 2004

Lysozyme

Kluveromyces lactis (recomb. human lysozyme)

Maullu et al. 1999

Proteinases

Serratia marcesens

Romero et al. 1997

Transglutaminase

Streptoverticillium mobaraense

Zhu et al. 1995

Ribonucleotides

Kluveromyces fragilis

Belem & Lee 2002

Riboflavin

Ashbya gossypii Torulopsis candida

Erturk et al. 1998 Buzzini & Rossi 1997

Carotenoids

Rhodotorula rubra/ Kluveromyces lactis

Frengova et al. 2004

enzymes, nisin, ethanol and nucleotides. Most of these products can be sold for a premium.

Many of the organisms selected to ferment whey are able to utilise lactose as their primary energy source. However, to increase the range of fermentation by-products, some micro-organisms have been grown with immobilised P-galactosidase, or co-fermented with another organism able to utilise lactose, e.g. lactose fermenting Lactobacillus helveticus are grown with Gluconobacter oxydans to produce acetate. In recent years, microorganisms have been manipulated so they are able to ferment lactose. For example recombinant DNA techniques can be used to convert Saccharomyces cerevisiae using genes from Kluveromyces marxianus to enable them to utilise lactose. Alternatively some organisms have been challenged to form mutations, so creating mutants able to utilise lactose, e.g. Schizosaccharomyces pombe.

Fermentation also creates waste by-products, such as spent fermentation liquor or stillage from alcohol production. These require further treatment to recover biomass for use as stock feed, or wastewater treatment prior to disposal over paddocks as fertiliser.

Whey powder

Evaporation and spray drying are the generally accepted methods for the disposal of large quantities of whey and a whey drying plant is often an integral part of a cheese factory (Caric 1994). Whey powder is used in a wide range of foods, mostly as a lower cost skim milk replacer, and in animal food. The properties of the whey powder are mainly governed by the amount of lactose converted to a-monohydrate crystals before drying, creating a non-hygroscopic free-flowing product. If the lactose in the liquid whey is not crystallised the resulting high levels of amorphous lactose in the dried whey will lead to caking and poor storage stability (Listiohadi et al. 2005a, 2005b).

Whey is evaporated to 50-60% total solids, then pre-crystallised by cooling with mixing for 15-24 h to create a large number of crystal nuclei. This ensures non-hygroscopic a-lactose monohydrate is the dominant crystal form. The slurry is spray dried and then finished off in a fluidised bed drier to slowly equilibrate the moisture and maximise the content of a-lactose monohydrate.

New technology, known as the Paradry process, has been developed to improve the drying of hygroscopic liquids. This process has been designed for evaporation of liquids with high total solids contents, high viscosity or tendency to fouling. It is continuous, has low operating costs and produces a non-caking powder (Anon. 2003). The Paradry process commences with concentration to higher solids (75% for whey powder) using the Paraflash evaporator. The concentrate is continuously crystallised with mixing to obtain 90% crystallisation, forming a dough or granulated paste which is rapidly dried in the spin-flash drier (Anderson 2001).

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