Cheese separation from whey

Cheese is a concentrated dairy food produced from milk curds that are separated from whey. The curds may be partially degraded by natural milk or microbial enzymes during ripening, as in cured cheeses, or they may be consumed fresh, as in uncured cheeses like cottage cheese. Most commonly, a bacterial culture with the aid of a coagulating enzyme like rennin is responsible for producing the initial curd. The... 

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. 

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). 

In cheese making, the casein is separated from the liquid part of the milk — the whey. It is then pressed and stored until ripe. The flavors of cheeses arc caused mostly by esters created during the ripening. 

Figure 7.21 Cheese is separated into curds and whey by the addition of bacteria. The liquid, whey, is separated from the curds which are then...

The second whey separation process uses both ultrafiltration and reverse osmosis to obtain useful protein from the whey produced in the traditional cheese manufacturing process. A flow schematic of a combined ultrafiltration-reverse osmosis process is shown in Figure 6.23. The goal is to separate the whey into three streams, the most valuable of which is the concentrated protein fraction stripped of salts and lactose. Because raw whey has a high lactose concentration, before the whey protein can be used as a concentrate, the protein concentration must be increased to at least 60-70% on a dry basis and the lactose content... 

Cheese is made by coagulating milk by the addition of rennet to produce curds. The curds are separated from the liquid whey and then processed and matured to produce a wide variety of cheeses. The active ingredient of rennet is the enzyme chymosin. Until 1990, most rennet was produced from the stomach of slaughtered newly born calves. These days, at a cost one tenth of that before 1990, chymosin is produced by genetically engineered bacteria into which the gene for this enzyme has been inserted, and is used for making cheese in the United States, Europe, and other parts of the world. 

Ultrafiltration Liquid Microporous membrane with pressure gradient Separation of whey from cheese... 

Improvement of membrane separation technology has resulted in the isolation of MFGM-enriched material from commercially available products. A phospholipid-rich fraction can be extracted from whey (Boyd et al., 1999) and buttermilk (Sachedva and Buchheim, 1997) with a reported yield of 0.25 g of phospholipids/g of protein in buttermilk (Sachdeva and Buchheim, 1997). Microfiltration of whey derived from the Cheddar cheese process, using 0.2 pm ceramic filters results in a fraction containing two major phospholipids, phosphatidylcholine and phosphatidylethanolamine, and lesser amounts of phosphatidylinositol, phosphatidylserine, sphingomyelin and cerebrosides (Boyd et al., 1999). The phospholipid fraction separated from the total lipids contains a larger proportion of mono- and polyunsaturated fatty acids (mainly oleic, Cig i and linoleic, C ) compared to the total lipid and the neutral lipid fraction (Boyd et al., 1999). 

Filtration of small (nano) particles from solvent using a filter with extremely small pores (0.001-0.010 micron) finer than ultrafiltration, not as fine as reverse osmosis. Used for the removal of viruses from plasma protein products. See Yaroshchuk, A.E., Dielectric exclusion of ions from membranes, Adv. Colloid Interface Sci. 85,193-230,2000 Rossano, R., D Elia, A., and Riccio, R, One-step separation from lactose recovery and purification of major cheese-whey proteins by hydroxyapatite — a flexible... 

Propionic acid and its derivatives are used in food, perfume and plastic applications. Traditional processes for making this compound, however, have limited productivity due to the low growth rate of the propionic bacteria and the inhibitory effect of the acid on the fermentation. The cheese whey permeate can be an inexpensive source of propionic acid. Propionic acids can be produced by fermentation of sweet whey permeate in a stirred tank reactor with cells separated from the medium and recycled back to the reactor by an ultrafiltration Z1O2 membrane on a carbon support [Boyaval and Corre, 1987]. This arrangement reduces the propionic acid concentration and increases the... 

Prokopek, D., Voss, E., and Thomasow, J., Manufacture of soft cheese without whey separation from ultrafiltered skim milk, Molkerei-Zeitung Welt. Milch., 29, 939, 1975. 

Fig. 1 Flow diagram for lactic acid production and separation from cheese whey...

The principle of making milk into cheese is simple the milk is soured with a bacterial culture, then rennet (an enzyme from the stomach of cows) is added, which causes curds to form—the basic ingredient of cheese. The cheese is separated from the whey, then salted and dried. 

Lactose (milk sugar), C12H22O11.H2O, occurs in the milk of mammals, in which it is present to the extent of from three to five per cent. It is obtained as a b3 -product in the manufacture of cheese. When rennet is added to milk, the casein and fat which the milk contains are precipitated. The liquid, called whey, after separation from the solid material by pressure, is neutralized with calcium carbonate, filtered, and evaporated to crystallization. The lactose so obtained forms large, hard, rhombic crystals, which contain one molecule of water of crystallization. 

This is not to say that milk has no colored substances. It does. Milk contains riboflavin, or vitamin B2, an important enzyme cofactor that has a greenish-yellow hue. Riboflavin is water soluble, so its color is easiest to see in the whey that forms when the liquid portion of milk is separated from the solids, as it is in cheese making. The fat globules in milk have a yellow tinge due to carotenoids, such as beta-carotene, which come from the diet of the milk source. Beta-carotene has nutritional importance because it is a precursor to vitamin A. Summer cow s milk is yellower that winter cow s milk because of what the cows have been eating — fresh green grass has more beta-carotene than hay does. 

It is not within the scope of this work to give even a cursory description of the various methods of cheese manufacture. It will be sufficient to indicate the principle in its most general aspects. Milk, skimmed or not skimmed, is first of all coagulated under conditions determined by the nature of the products desired. The curd is then more or less completely separated from the whey, either by a simple mechanical division (soft cheeses), or by a stirring effected during a moderate heating (cooked cheeses), and is then collected and put in the mould. Draining ensues and, if it is necessary, the excess whey is expelled by means of a... 

Dried whey from soft or fresh cheese production. Whey is the liquid that separates from the curd (n = 114). 

In cheese-making, the term whey refers to the dilute O/W emulsion that separates from the cot -ulated portion or curd. 

Therefore, while it is safe to say feat a given UF membrane could separate the much smaller lactose from the much larger protein in whey, it is dangerous to assume that selected proteins could be separated from each other without experimental evidence. All microporous filtration (MF, UF and RO) deals with purification, fractionation, concentration or partition. An example of purification is pressure-driven UF removal of particles and high-molecular-wei t species from water subsequendy to be used in hollow-fiber RO desalination. An example of pressure-driven fractionation is separation of protein and lactose from cheese whey for use as food additives (in the... 

Cheese making—During this process, milk is clotted by either acid or rennet (an enzyme-containing substance derived from animal stomachs) so that it separates into cheese and whey. Usually, much more calcium and phosphorus are lost in the whey from acid-clotted items like cottage cheese than from the rennet-clotted cheeses like Cheddar and Swiss. 

The fourth fully developed membrane process is electrodialysis, in which charged membranes are used to separate ions from aqueous solutions under the driving force of an electrical potential difference. The process utilizes an electrodialysis stack, built on the plate-and-frame principle, containing several hundred individual cells formed by a pair of anion- and cation-exchange membranes. The principal current appHcation of electrodialysis is the desalting of brackish groundwater. However, industrial use of the process in the food industry, for example to deionize cheese whey, is growing, as is its use in poUution-control appHcations. 

The pore size of porous titania can be up to 2000 A. Titania is used for the purification of proteins and as a support for bound enzymes. The purification of /1-lactoglobulin from cheese whey, of protease from pineapple, /5-lactamase, and amylase can be achieved with titania. The latter two purifications are impossible on alumina. Titania is also used as a support in peptide synthesis. The separation of plasmid DNA is shown in Figure 3.24. 

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