Whey drying

Food products such as milk powder, coffee, tea, com syrup solids, starches, potatoes, eggs, cheese, fruit and vegetable powders, and so on are usually spray dried. All dryers can be fitted with cyclone collectors to collect the fine particles that do not settle in the dryer chamber. If necessary, the cyclone can be backed up with a fabric collector unless the powder is hygroscopic, in which case a wet scrubber may be used. Emission factors for cheese drying and whey drying in natural and processed cheese manufacture are shown in Table 53.23. 

WHEY. Whey is the watery part of milk separated from the curd. Whey is available as dried whey, condensed whey, dried whey solubles, condensed whey solubles, dried hydrolyzed whey, condensed hydrolyzed whey, condensed whey product, dried whey product, and condensed cultured whey. 

K. marxianus var. fragilis which utilizes lactose, produces a food-giade yeast product from cheese whey or cheese whey permeates collected from ultrafiltration processes at cheese plants. Again, the process is similar to that used with C. utilis (2,63). The Provesteen process can produce fragiUs yeast from cheese whey or cheese whey permeate at cell concentrations ia the range of 110—120 g/L, dry wt basis (70,73). 

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). 

Foam spray dryiag coasists of forcing gas, usuaHy air or nitrogea, iato the product stream at 1.38 MPa (200 psi) ahead of the pump ia the normal spray dryer circuit. This method improves some of the characteristics of dried milk, such as dispersibHity, bulk deasity, and uniformity. The foam—spray dryer can accept a condensed product with 60% total soHds, as compared to 50% without the foam process. The usual neutralization of acid whey is avoided with the foam—spray dryer (see Drying Foams Sprays). 

Buttermilk. Buttermilk is drained from butter (chum) after butter granules are formed as such, it is the fluid other than the fat which is removed by churning. Buttermilk may be used as a beverage or may be dried and used for baking. Buttermilk from churning is - 91% water and 9% total sohds. Total sohds include lactose [598-82-3] 4.5% nitrogenous matter, 3.4% ash, 0.7% and fat, 0.4%. Table 17 gives the U.S. specifications for dry buttermilk (DBM) and whey. 

Property Spray process DBM RoUer process DBM Dry whey, extra... 

Ultrafiltration. Membranes are used that are capable of selectively passing large molecules (>500 daltons). Pressures of 0.1—1.4 MPa (<200 psi) are exerted over the solution to overcome the osmotic pressure, while providing an adequate dow through the membrane for use. Ultrafiltration (qv) has been particulady successhil for the separation of whey from cheese. It separates protein from lactose and mineral salts, protein being the concentrate. Ultrafiltration is also used to obtain a protein-rich concentrate of skimmed milk from which cheese is made. The whey protein obtained by ultrafiltration is 50—80% protein which can be spray dried. 

The ratio of a-lactose [10039-26-6] and P-lactose in dry milk and whey varies according to the speed and temperature of drying. An aqueous solution at equiHbrium at 25°C contains 35% a- and 63% -lactose. The latter is more soluble and sweeter than DL-lactose and is obtained by heating an 80% DL-lactose [63-42-3] solution above 93.5°C, foUowed by drying on a dmm or roUer dryer. Lactose is used for foods and pharmaceutical products. 

Milk and Milk Replacers. White pan bread was long made with about 3—4% nonfat dry milk (NEDM) in the United States, for reasons of enhanced nutrition, increased dough absorption, improved cmst color, fermentation buffering, and better flavor. Eor some years, however, sharply increased milk prices have led to a decline in its use in breadmaking. Many bakers have turned to the use of milk replacers to control the costs of their products, and these ingredients are now commonly utilized. Milk replacers were designed to dupHcate some of the functions and nutrition of milk. These blends may contain soy flour or cereals, with whey, buttermilk soHds, sodium or calcium caseinate, or NEDM. Milk replacers or NEDM used in bread dough amount to about 1—2%, based on flour. 

A wide number of proteia sources are available for use ia dairy substitutes. These iaclude animal proteias, ie, skim milk ia Hquid, coadeased, or dry form (filled products) caseia, caseiaates, and coprecipitates whey proteias oil-seed proteias, fish proteias and blood proteias. Oil-seed proteia sources iaclude soybean proteia coaceatrates and isolates, groundnut proteia, cottoaseed proteia, and sunflower seed, rapeseed, coconut, and sesame seed proteias (see Soybeans AND other oil seed). Other sources are leaf and single-cell proteias (see Foods, nonconventional). Of these proteia sources, milk and soybean proteias are most widely used. Proteia usage is based oa economics, flavor, fuactioaahty, and availabiUty. 

Whey is the fluid obtained by separatiag the coagulum from cream and/or skim milk, and is a by-product of either caseia or cheese manufacture. The composition of whey is determined by the method of curd formation, curd handling practices, and methods of handling whey as it is separated from the curd. Dried acid whey contains ca 12.5 wt % proteia (total nitrogea x6.38), 11.0 wt % ash, and 59 wt % lactose, whereas sweet whey contains 13.5 wt % proteia, 1.2 wt % fat, 8.4 wt % ash and 74 wt % lactose. The composition varies with the type of acid used (7). 

Soybean-based ice cream products, technologically feasible, are generally not in use because of flavor problems. An acceptable ice cream has been made by replacing 50% of the nonfat milk soHds with a dried soy protein isolate made up of cheese whey (21). Chocolate flavor has been widely used to mask the flavor of soybean proteins in ice cream (see Flavors and spices). 

NOTE Compiled hy John A. Goff and S. Gratch. See also Keenan and Kaye. Theimodynamic Propeities of Air, Whey, New York, 1945. Enthalpy of dry air taken as zero at 0 F. Enthalpy of hquid water taken as zero at 32 F. 

Milk is converted in the creamery and associated factories to whole or market milk, skimmed milk, creams, hutters, cheeses, dried milk, whey, yoghurts, hutter oil, condensed milk, milk powder and ice cream [46]. 

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... 

Milk from cows contains 3.2% protein, about 80% of which is casein. Casein is isolated by a precipitation process from milk, involving heating, rinsing to remove whey, and drying to a powder. The yield is about 3 kg/ 100 kg skim milk. Rennet casein is obtained when the casein is precipitated by chymosin enzyme, also known as rennet, and acid casein is produced when precipitation is accomplished by acidification. Acid casein is usually found in the form of sodium caseinate or calcium caseinate, which are water-soluble salts. Caseinates are made by reacting NaOH or CaOH with a slurry of casein curd or powder and then spray drying (Southward, 2010). 

The range of whey products that are used include, for example, ultra-filtered and dried WPC, which contains between 20% and 89% protein ion exchange and membrane filtered WPI, which contains at least 90-95% protein (Tunick, 2008) and other whey fraction-enriched products such as p-lactalbumin. These enriched protein whey products can be texturized and used in the manufacture of high-protein content puffed com products (Onwulata et al, 2010). 

Purely thermal denaturation of proteins requires much longer times collagen in moist heat below 120 °C needs 30 min to denature (Meyer et ah, 2005), wheat glutens must be subjected to 200-215 °C of dry heat for 72 min (Friedman et ah, 1987), and as mentioned above, whey proteins require at least 50 °C and 30 min for texturization without the use of extrusion processing. 

FIGURE 5.3 Electron micrographs of whey protein isolate (WPI). Scanning electron microscopy of dry WPI powder (A). Transmission electron microscopy of WPI stained with uranyl acetate (B) nonextruded WPI Paste (40% moisture) and (C) extruded texturized WPI (100 °C, 40% moisture) (Onwulata et ai, 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). 

Nalesnik, C., Onwulata, C., Tunick, M., Phillips, J., and Tomasula, P. (2007). The effects of drying on the properties of extruded whey protein concentrates and isolates. /. Food Eng. 80, 688-694. 

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