Pasteur affect

Shumaker, E.K. and Wendorff, W.L., Factors affecting pink discoloration in annatto-colored pasteurized process cheese, J. Food ScL, 63, 828, 1998. 

Another issue in the preparation of reference material is the required shelf life. The shelf life of reference material is the time that it remains stable under proper storage conditions. Depending on the nature of the mechanisms affecting the stability of the material, various actions can be taken to improve the shelf life. Reduction of the moisture content is one of the first options to be considered. In many cases, moisture plays a key role in mechanisms leading to instability of the matrix and/or parameters. In other cases, sterilization or pasteurization of the material might be considered in order to stop bacterial activity. When preparing solutions, additives may increase the shelf life. Obviously, the shelf life of material is also a function of the storage conditions. 

During processing, affected fruit is generally removed or pressurized-water jets are utilized to remove damaged portions of fruit and contaminations (or both). These processes effectively eliminate patulin. However, if these procedures are not done properly, patulin may remain in the processed apple juice and apple products, where it is very stable. Pasteurization at 90°C only causes a reduction of 10%, however patulin is not stable in the presence of sulfur dioxide or sulfydryl compounds. The fermentation process for cider eliminates 99% of patulin. 

Milk contains about 0.1 mg niacin per 100 g and thus is not a rich source of the preformed vitamin. Tryptophan contributes roughly 0.7 mg NE per 100 g milk. In milk, niacin exists primarily as nicotinamide and its concentration does not appear to be affected greatly by breed of cow, feed, season or stage of lactation. Pasteurized goats (0.3 mg niacin and 0.7 mg NE from tryptophan per 100 g) and raw sheep s (0.4 mg niacin and 1.3 mg NE from tryptophan per 100 g) milk are somewhat richer than cows milk. Niacin levels in human milk are 0.2 mg niacin and 0.5 mg NE from tryptophan per 100 g. The concentration of niacin in most dairy products is low (Appendix 6A) but is compensated somewhat by tryptophan released on hydrolysis of the proteins. 

For practical purposes, the nutritional quality of UHT milk is similar to that of conventionally pasteurized milk (Miller 1985 Arnold and Roberts 1982 Burton 1980, 1982 Renner 1980 Kosaric et al. 1981 Katz et al. 1981 Ford and Thompson 1981). As with conventionally pasteurized milk, the degree of heat treatment and the conditions of storage can affect the nutrient content of the milk (Burton 1980,1982 Renner 1980 Kosaric et al. 1981 Ford and Thompson 1981 Mehta 1980). However, careful controls on UHT processing, along with proper packaging, can ensure that the nutritional value of milk with regard to protein, fat, carbohydrate, fat-soluble vitamins, most water-soluble vitamins, and minerals is retained (Ford and Thompson 1981). 

Radiation Biochemistry of Carbohydrates. Normal autolytic processes are not affected by pasteurizing doses of ionizing radiation. The principal source of volatile base in irradiated and unirradiated or sterile fish or shellfish tissues is through enzymatic amination of adenosine monophosphate to the flavor-active compound inosine monophosphate. 

Since the direct estimation of microbial numbers by conventional culturing methods is time-consuming and well affected by environmental conditions (18), a simple test for the most resistant enzyme activity is appropriate on a routine basis. If enzyme activity is detected, it can be assumed that the heat treatment was inadequate (4,15). Appropriately, GFPuv can be employed as a BI in thermal processes (blanching, pasteurization, disinfection) at temperatures >75°C for products at pH > 5.5, with the inactivation of GFPuv shown to be directly related to the time of exposure to moist heat and pH. 

Karatapanis, A. E., Badeka, A. V., Riganakos, K. A., Savvaidis, I. N., and Kontominas, M. G. (2006). Changes in flavour volatiles of whole pasteurized milk as affected by packaging material and storage time. Int. Dairy. 16, 750-761. 

Studies on the functional significance of MFGM-associated enzymes have been restricted largely to their involvement in degradative events that affect processing properties or flavor, or for their use as markers of adequate pasteurization. Obviously, enzymes that can produce product defects are of great concern to the dairy industry. Unfortunately, the biological roles... 

Mastitis and microbial contamination can also contribute to hydrolytic rancidity. In general, lipolysis caused by indigenous milk lipase accounts for most of the rancidity in raw milk and cream microbial lipolysis is of minor practical importance as little if any lipolysis occurs before the bacterial population reaches 106—107 cfu/ml (Suhren and Reichmuth, 1990). However, in stored milk products, lipolysis by microbial lipases is of greatest significance. Short shelf-life products such as pasteurized milks may be affected by pre-pasteurization lipolysis caused by milk lipase but may be affected by bacterial lipolysis at the end of their shelf-life (Deeth et al., 2002). 

Vitamin D is extremely stable, and little or no loss is experienced in processing and storage. Vitamin D in milk is not affected by pasteurization, boiling, or sterilization (Hartman and Dryden 1965). Frozen storage of milk or butter also has little or no effect on vitamin D levels, and the same result is obtained during storage of dry milk. 

A chiral object and its mirror image are enantiomorphous, and they are each other s enantiomorphs. Louis Pasteur (Figure 2-37) was the first who suggested that molecules can be chiral. In his famous experiment in 1848, he recrystallized a salt of tartaric acid and obtained two kinds of small crystals which were mirror images of each other as seen by Pasteur s models in Figure 2-38 preserved at Institut Pasteur at Paris. Originally Pasteur may have been motivated to make these large-scale models because Jean Baptiste Biot, the discoverer of optical activity had very poor vision by the time of Pasteur s discovery [42], Pasteur demonstrated chirality to Biot, who was visibly affected... 

Unlike UHT pasteurization, MF can reduce the amount of bacteria and spores without affecting the taste of the milk, and provides longer shelf life than pasteurization [6,52,87],... 

Acesulfame potassium possesses good stability. In the bulk form it shows no sign of decomposition at ambient temperature over many years. In aqueous solutions (pH 3.0-3.5 at 20°C) no reduction in sweetness was observed over a period of approximately 2 years. Stability at elevated temperatures is good, although some decomposition was noted following storage at 40°C for several months. Sterilization and pasteurization do not affect the taste of acesulfame potassium. ... 

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