Milk Treatment

Milk contains a large number of natural enzymes, some of which, such as lipase and phosphatase, are destroyed by pasteurization. The presence of phosphatase in milk is used in quahty control to determine whether the milk has been adequately pasteurized. Milk lipases may lead to undesirable rancidity if freshly drawn milk is 

Cation-exchanger resins can be used as acid catalysts to hydrolyze casein, the resulting amino acid mixture serving as a good bacterial nutrient medium. 

A stabilization problem with conventional ice cream is that at deep-freeze temperatures they cannot be served or eaten as readily as when they are at normal eating temperature. Reformulation to ensure such properties, e.g., spoonability at deepfreeze temperatures, as approximately those expected at normal eating tanperatures is comparatively simple. The difficulty is that such reformulation leads to products that do not have acceptable properties at normal eating temperatures. The properties of ice creams, that have the serving and eating properties conventionally expected at normal eating temperatures and that are sufficiently stable, are improved by 

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J. L. Maubois, "AppHcation of Ultrafiltration to Milk Treatment for Cheese Making," in Ref. 27. 

In both sexes, CCM-OJ provided an alkali load that significantly increased urinary pH compared to basal levels and versus milk consumption, and also increased urinary citrate excretion versus basal levels. An elevated urine pH and citrate level are generally considered to reduce Ca oxalate supersaturation and crystallization potential (Odvina, 2006). However, in this study the relative supersaturation measurement for Ca oxalate was not different between the CCM-OJ and milk treatment groups, or between either treatment and the basal levels. Although the alkalizing effect of milk was less than that of CCM-OJ, it also induced a higher urinary pH compared to basal levels (p <. 01 and p <. 05 in women and men, respectively). 

Milk treatment tends to be confined to batch processes since continuous processing with immobilized enzyme results in microbial contamination, which is encouraged because mild conditions of temperature and pH have to be used. 

Pack, M. Y., Vedamuthu, E. R., Sandine, W. E. andElliker, P. R. 1968. Hydrogen peroxide-catalase milk treatment for enhancement and stabilization of diacetyl in lactic starter cultures. J. Dairy Sci. 51, 511-516. 

Head and Hansen (415) added L-ascorbic acid (42.3 mg/L) to whole, chocolate, and low fat (1%) fluid milks to increase the ascorbic acid intake of school children. Three milk treatments were examined (C) pasteurized milk, (E) pasteurization (74°C for 16 s) after ascorbic acid addition, and (F) ascorbic acid addition after pasteurization. Storage (4°C) retention of ascorbic acid (Figure 9) was good, and the taste reactions of children were favorable. Previously Weinstein et al. (416) and Anderson et al. (417) had reported on ascorbic acid nutrified fluid milk to which ascorbic acid was added at 50 and 200 mg/L, respectively. Infant milks nutrified with ascorbic acid were investigated by Cameron (418) during the preparatory procedures prior to infant feeding. 

Figure 26. Microbial growth (a) and metabolic heat rate (b) fix>m milk kept at 30 as affected by pasteurization (P), lactoperoxydase system (LPS) activation and untreated raw milk (C). A highly significant interaction (P < 0.001) was found between milk treatment and incubation period [40]. (With permission from Elsevier.)...

Reverse osmosis is used for desalination of seawater, treatment of recycle water in chemical plants and separation of industrial wastes. More recently the technique has been applied to concentration and dehydrogenation of food products such as milk and fruit juices. See ultrafiltralion. 

Brine Preparation. Sodium chloride solutions are occasionally available naturally but they are more often obtained by solution mining of salt deposits. Raw, near-saturated brines containing low concentrations of impurities such as magnesium and calcium salts, are purified to prevent scaling of processing equipment and contamination of the product. Some brines also contain significant amounts of sulfates (see Chemicals FROMBRINe). Brine is usually purified by a lime—soda treatment where the magnesium is precipitated with milk of lime (Ca(OH)2) and the calcium precipitated with soda ash. After separation from the precipitated impurities, the brine is sent to the ammonia absorbers. 

An airspace heater ejects steam into the airspace above the product and into the foam, maintaining a temperature at least 5°C above the minimum hoi ding temperature of 63°C. The time—temperature exposure is recorded on a chart which must be kept for proof of treatment. If the Hd is opened, and the milk temperature falls below 63°C, the exposure is intermpted causing the pasteurization cycle to restart. 

Fig. 7. Homogenization of regenerated milk A, after HTST heat treatment, and B, before HTST pasteurization. Details of bypass, relief lines, equalizer,...

Vacuum Treatment. Milk can be exposed to a vacuum to remove low boiling substances, eg, onions, garlic, and some silage, which may impart off-flavors to the milk, particularly the fat portion. A three-stage vacuum unit, known as a vacreator, produces pressures of 17, 51—68, and 88—95 kPa (127, 381—508, and 660—711 mm Hg). A continuous vacuum unit in the HTST system may consist of one or two chambers and be heated by Hve steam, with an equivalent release of water by evaporation, or flash steam to carry off the volatiles. If Hve steam is used, it must be cuUnary steam which is produced by heating potable water with an indirect heat exchanger. Dry saturated steam is desired for food processing operations. 

Irradiation. Although no irradiation systems for pasteurization have been approved by the U.S. Food and Dmg Administration, milk can be pasteurized or sterilized by P tays produced by an electron accelerator or y-rays produced by cobalt-60. Bacteria and enzymes in milk are more resistant to irradiation than higher life forms. For pasteurization, 5000—7500 Gy (500,000—750,000 tad) are requited, and for inactivating enzymes at least 20,000 Gy (2,000,000 rad). Much lower radiation, about 70 Gy (7000 tad), causes an off-flavor. A combination of heat treatment and irradiation may prove to be the most acceptable approach. 

Phosphatase Test. The phosphatase [9001-78-9] test is a chemical method for measuring the efficiency of pasteurization. AH raw milk contains phosphatase and the thermal resistance of this enzyme is greater than that of pathogens over the range of time and temperature of heat treatments recognized for proper pasteurization. Phosphatase tests are based on the principle that alkaline phosphatase is able, under proper conditions of temperature and pH, to Hberate phenol [108-95-2] from a disodium phenyl phosphate substrate. The amount of Hberated phenol, which is proportional to the amount of enzyme present, is determined by the reaction of Hberated phenol with 2,6-dichloroquinone chloroimide and colorimetric measurement of the indophenol blue formed. Under-pasteurization as well as contamination of a properly pasteurized product with raw milk can be detected by this test. 

Casein. Milk contains proteins and essential amino acids lacking in many other foods. Casein is the principal protein in the skimmed milk (nonfat) portion of milk (3—4% of the weight). After it is removed from the Hquid portion of milk, whey remains. Whey can be denatured by heat treatment of 85°C for 15 minutes. Various protein fractions are identified as a-, P-, and y-casein, and 5-lactoglobulin and blood—semm albumin, each having specific characteristics for various uses. Table 21 gives the concentration and composition of milk proteins. 

Magnitude of the residue in meat/milk/poultry/eggs (feeding/dermal treatment) Crop field trials (for each crop use, in each geographic location)... 

The development of analytical strategies for the regulatory control of dmg residues in food-producing animals has also been reviewed (128). Because of the complexity of biological matrices such as eggs (qv), milk, meat, and dmg feeds, weU-designed off-line or on-line sample treatment procedures are essential. 

Parallel to the activities in the treatment of pernicious anemia were observations in the 1930s that most farm animals had a requirement for an unknown factor beyond the vitamins then known. The lack of this factor became apparent, eg, when chicks or pigs fed a diet with only vegetable protein evidenced slow growth rate and high mortahty. It became apparent that the requited factor, termed animal protein factor, was present in animal sources such as meat and tissue extracts, milk whey, and cow manure. Subsequent to its isolation, it was rapidly shown that vitamin B 2 is the same as animal protein factor. 

In the treatment of diseases where the metaboUtes are not being deUvered to the system, synthetic metaboUtes or active analogues have been successfully adrninistered. Vitamin metaboUtes have been successfully used for treatment of milk fever ia catde, turkey leg weakness, plaque psoriasis, and osteoporosis and renal osteodystrophy ia humans. Many of these clinical studies are outlined ia References 6, 16, 40, 51, and 141. The vitamin D receptor complex is a member of the gene superfamily of transcriptional activators, and 1,25 dihydroxy vitamin D is thus supportive of selective cell differentiation. In addition to mineral homeostasis mediated ia the iatestiae, kidney, and bone, the metaboUte acts on the immune system, P-ceUs of the pancreas (iasulin secretion), cerebellum, and hypothalamus. 

Correlation of all aspects of the test method with the practical system of interest is always important. The test used for dairy cleaning is an excellent example (116). Milk is used to tag the soil with radioactive Ca by an exchange with radioactive CaCl2. This treatment is apphed to stainless steel planchets by suspending the planchets in milk under actual pasteurizing conditions. 

Chloramine-T, sodium A/-chloro-/)-toluenesulfonamide [127-65-17, was widely used during World War I for the treatment of infected wounds, and subsequentiy for hygienic purposes such as mouthwashes, douches, etc. It can be used for sanitising food-handling equipment, but its activity is considerably slower than that of hypochlorites. The Grade A Pasteurized Milk Ordinance (1985) and the Ordinance and Code for Restaurants (1948) of the U.S. Pubhc Health Service permitted the use of chloramine-T. 

Tetracycline antibiotics have found wide application in animal industries for treatment, preventive maintenance and stimulation of growth of large horned livestock owing to what their residue amounts can be present at milk and meat of animals. Residue amounts of antibiotics are not toxic, however, capable to cause allergic reactions and to promote development of tolerance of the some people pathogenic bacterias. According with the legislative requirements of a number of the European countries it is forbidden to deliver to the population production polluted residual contents of tetracyclines. 

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