Whey protein production

Three different whey protein products extruded at the cook temperature of 75 °C resulted in varying degrees of melt texturization (Table 5.3). Among the whey proteins, WPC (WPC80) was the least texturized. Whey lactalbumin (WLAC) and WPI were both significantly (p < 0.05) more texturized, but a wider spread of texturization was observed for WPI, the initial and final values were from 28% to 94.8%, and therefore more emphasis was placed on studying WPI (Onwulata et ah, 2006). 

Tunick, M. (2008). Whey protein production and utilization. In "Whey Processing, Functionality and Health Benefits", (C. 1. Onwulata and P. J. Huth, Eds), pp. 1-13. Blackwell Publishing and IFT Press, Ames, lA. 

Walsh, M. K. and Wood, A. M. (2010). Properties of extrusion-expanded whey protein products containing fiber. Int. J. Food Prop. 13,702-712. 

Lactalbumin is an insoluble whey protein product produced by heating whey to high temperatures ( > 90 C) to denature and render the proteins insoluble when adjusted to isoelectric conditions by the addition of acid. These proteins offer little functionality in emulsification applications. 

Several casein and whey protein products are commercially manufactured from skim milk and whey (Fox 1970 Richert 1975 Morr 1975, 1979 Muller 1982A,B Marshall 1982). These protein products are used as nutritional and functional ingredients throughout the food industry (Hugunin and Ewing 1977). 

Although whey protein products have several food uses, the lactose contained in the permeate is less valuable, and many plants discharge the permeate to a biological wastewater treatment plant. A few plants recover lactose as dry lactose sugar, as shown in Figure 6.23. Some plants also ferment the lactose concentrate to make ethanol. An introduction to membrane ultrafiltration in cheese production is given by Kosikowski [26],... 

Although heat-denatured whey protein, referred to as lactalbumin, has been available for many years for food applications, it was of little significance, mainly because the product is insoluble and therefore has limited functionality. The commercial production of functional whey protein became possible with the development of ultrafiltration in the 1960s. Whey protein concentrates (WPCs) produced by ultrafiltration are now of major commercial importance, with many specific food applications. Superior whey protein products (whey protein isolates, WPI) are being produced on a limited scale by chromatography, although their substantially higher cost has limited their production. 

The use of ion-exchange resins (Figure 4.41) offers an effective method for the preparation of high-quality whey protein products, referred to as whey protein isolates (WPI), containing 90-95% protein (see Marshall, 1982 Mulvihill, 1992). Although the functional properties of WPI are superior to those of WPCs on an equiprotein basis (due to lower levels of lipids, lactose and salts), their production is rather limited, due to higher production costs. 

Protein-Based Substitutes. Several plant and animal-based proteins have been used in processed meat products to increase yields, reduce reformulation costs, enhance specific functional properties, and decrease fat content. Examples of these protein additives are wheat flour, wheat gluten, soy flour, soy protein concentrate, soy protein isolate, textured soy protein, cottonseed flour, oat flour, com germ meal, nonfat dry milk, caseinates, whey proteins, surimi, blood plasma, and egg proteins. Most of these protein ingredients can be included in cooked sausages with a maximum level allowed up to 3.5% of the formulation, except soy protein isolate and caseinates are restricted to 2% (44). 

There are no universally accepted definitions of substitute dairy foods, which are referred to as imitations, simulates, substitutes, analogues, and mimics and are associated with terms such as filled, nondairy, vegetable nondairy, and artificial milk, cheese, etc. The term nondairy has been used indiscriminately to describe both imitation dairy products and products legally defined as not being imitation dairy products. Dairy substitutes can be divided into three types those in which an animal or vegetable fat has been substituted for milk fat those that contain a milk component, eg, casein [9000-71-9] or whey protein and those that contain no milk components (see Milk and milkproducts). The first two types make up most of the substitute dairy products. 

Whey proteins that have been heat precipitated under very high shear have a particle size between 1 and 3 micrometers, and give the impression of fat in some products. These microparticulated whey proteins are being used as fat replacers in frozen desserts and processed cheese substitutes. 

Figure 4.4 The production of whey protein and Kluyveromyces lactis from whey.

The consumption of dairy products plays a significant role in providing high-quality protein, vitamins, minerals, and other bioactive compounds to the American diet. Dairy products are consumed fresh in the United States in the form of fluid milk, cheese, yogurt, butter, and ice cream. Dried and condensed products such as nonfat dried milk, whey, whey protein concentrates, and isolates are also produced which are used as ingredients to boost the nutritional and functional properties of a host of other food... 

The higher protein content whey products are used in many products, and have been mainly promoted for their health benefits. Our contribution is creating extrusion texturized whey products that expands the range of products that can contain whey proteins (Onwulata, 2009 Onwulata et al., 2010). 

Whey proteins are known to increase immune response and maintain muscle mass (Phillips et ah, 2009). In one instance, when an immunosti-mulatory vitamin and mineral mixture developed at Tufts University Human Nutrition Research Center on Aging was blended with texturized WPI (TWPI) in an extruded snack bar, immunostimulatory effects were enhanced in young (< 5 months) and old (> 22 months) mice fed ad libitum for 5 weeks. The mineral mixture and TWPI improved T cell proliferation and reduced upregulated production of proinflammatory mediators in... 

The constraint of extruding whey protein above the useful texturization range is keeping the temperature below the point where pyrolysis will occur as evidenced by relatively constant nitrogen content. However, texturized whey products are sometimes extruded at 150 °C to form... 

Polyacrylamide gel electrophoresis results suggest that p-LG undergoes a greater conformational loss as a fimction of extrusion temperature than a-LA, presumably due to intermolecular disulfide bond formation. Atomic force microscopy indicates that texturization results in a loss of secondary structure of aroimd 15%, total loss of globular structure at 78 °C, and conversion to a random coil at 100 °C (Qi and Onwulata, 2011). Moisture has a small effect on whey protein texturization, whereas temperature has the largest effect. Extrusion at or above 75 °C leads to a uniform densely packed polymeric product with no secondary structural elements (mostly a-helix) remaining (Qi and Onwulata, 2011). 

FIGURE 5.4 SDS-PAGE of extruded and nonextruded whey protein isolate. (A) With 2-mercaptoethanol (B) without 2-mercaptoethanol. The lanes are temperature and product conditions lane 1,100 °C lane 2, 75 °C lane 3, 50 °C lane 4,35 C lane 5, native WPI lane 6, laboratory whey (Onwulata et al., 2003a). 

FIGURE 5.6 Solubility of texturized dairy protein products extruded at different temperatures, 25 (control), 50, 75, and 100 C Nonfat dried milk (NDM) whey protein concentrate (WPC80), containing 80% protein and whey protein isolate (WPl), containing 95% protein (Onwulata et at, 2003a). 

Whey may be substituted for starch by as much as 25% in extruded corn snacks, but the product does not puff as much as com alone, as the water-holding whey protein does not react with the starch matrix (Onwulata et al., 1998). WPCs or isolates can be added along with starch to create expanded snack foods with boosted nutritional content however, without texturization, whey proteins in amounts larger than 15% may interfere with expansion, making the products less crunchy. To counter this effect, whey proteins can be texturized with starch to improve their interaction with other food components in a formulation, principally to increase extmdate expansion. In one successful application, between 25% and 35% of the flour was replaced with whey protein (Onwulata et al., 2001a,b). 

Cellulose, oat, and wheat fiber, which are all insoluble, have been incorporated with whey protein into an extruded product (Walsh and Wood, 2010). Increasing the fiber content led to decreases in air cell size. 

Extrusion is an effective means of denaturing whey proteins to create texturized products. TWP may be used as an ingredient to improve the characteristics of many foods. The production of snack foods wifh... 

It is demonstrated here that extrusion is an effective tool for texturing whey proteins to create new functions for dairy proteins and that thermally denatured WPl is a unique ingredient that can be used in large amounts in nontraditional applications for non-TWPl. This review covers the use of extrusion texturized dairy ingredients in foods however, there are other examples of fhe successful use of this technique along with the product, TWPl in different types of nonfood applications, such as in biodegradable films, and bioplastics. 

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