Recoverable Carbohydrates Fats and Proteins for Human and Animal Consumption

Currently, whey proteins are recovered from liquid whey for both human consumption and animal feed in limited quantities in the dairy industry. Whey proteins have found uses in infant formulae, in health foods, and in

Table 8.2. Potential products from wastewaters generated from different food-processing sectors of the food industry.

Sector

Waste Residuals in Water

Potential Applications

Meat, poultry, and fishery

Bakery and grain processing

Fruits and vegetables

Nut and oilseed

Dairy

Beverage

(nonalcohol) Beverage (alcohol)

Offal, blood, soluble proteins, DAF sludge

Spent brewer's yeast, starch, and waste grains

Trimmings, fruit pomace, and flavors

Oil, hulls, meal

Whey, lactose

Beverage spills, sugars

Beverage spills, wine grape residuals, brewery grain residuals

Animal feed, protein isolates, hormones, enzymes, savory compounds, vitamins, glue, gelatin, fish oils, and biodiesel Animal feed, lactic acid fermentation ingredients, fermentation feedstock, paper, and ethanol Feed ingredients in lactic acid fermentation, animal feed, flavors, and biofuels Fermentation feedstock, biofuels, and plastic filler (nutshell) Food ingredient, animal feed, fermentation feedstock for specialty chemicals, and biofuel Fermentation feedstock for specialty chemicals Biofuels and specialty chemicals (e.g., tartrate)

bakery goods. However, some cheese manufacturing plants in which whey is produced as a by-product of cheese making (80% of liquid milk ends up as whey) still don't have the technology (ultrafiltration) to process it. Only 70% of the total available whey is sold as a value-added commodity. In addition to unfamiliarity with the technology and the cost associated with the implementation of the technology to recover whey proteins, the supply and demand issue also plays a role in this imbalance. This imbalance problem can be solved only through discovery of new uses of whey proteins. The potential applications of recovered whey proteins (either as a whole or as individual components) as edible oxygen-barrier coatings on foods and grease barrier coating on paper used for the food service industry or gross coating of confectionery (being developed by the University of California at Davis) and pharmaceutical intermediate specialty chemicals in the future look promising.

Wastewaters generated in seafood and fish processing plants are enormous but contain no toxic substances and thus are readily available for recovery of food materials, some of which are soluble proteins. However, recovery of food materials from seafood and fish processing facilities are usually limited to large-scale operations because wastes from small processors do not have enough recoverable materials to justify the cost of operating even a small batch recovery unit. But where the recovery operation is applicable it is an excellent way to reduce BOD5 in wastewater and produce additional products to offset wastewater treatment. It is feasible to recover soluble proteins with a properly selected membrane separation process and then process the proteins into flour after fish oil is removed while screens and flotation devices can recover fish debris and greases from wastewater streams for used in animal feeds. As described in Chapter 3, membrane-based technologies have great potential to concentrate, to fractionate, and to purify organic and inorganic materials in aqueous solutions or suspensions, or they can be used as intermediate separation steps to facilitate efficient and economical recovery of value-added materials. In early days, membrane separations had been used primarily to recycle the wash water in seafood and fish processing operations (Pavia and Tyagi, 1972); the aim of the processing of wastewater from fish processing was not material recovery. Steadily, attentions have been paid to the economical effect of protein or enzyme recovery from fish processing wastewaters (Pedersen et al., 1987, 1989; Alfonso and Berquez, 2002).

In potato chip manufacturing facilities, a large amount of water is used for washing, peeling, slicing, blanching, and frying, and consequently, the wastewater generated in the plants contains a high content of starch (from washing, peeling, slicing, and blanching) and oil (from frying). Thus recovery of these materials can produce benefits of low BOD5 wastewater suitable for directly discharging into a municipal sewage system and useful materials sold for profits. Catarino et al. (2006) developed an integrated system to recover starch from wastewaters collected before frying using a series of hydrocyclones and a vacuum filter unit, whereas grease and oil were removed from a gravity settling tank.

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