Pasteurization temperature

The equipment needed includes a balance tank, regenerative heating unit, positive pump, plates for heating to pasteurization temperature, tube or plates for hoi ding the product for the specified time, a flow-diversion valve (FDV), and a cooling unit (Fig. 4). Often the homogenizer and booster pump also are incorporated into the HTST circuit. 

The final heater increases the regeneration temperature (- 60° C) to pasteurization temperature (at least 72°C) with hot water. The hot water is 1-2° C above the highest product temperature (73°C). Four to six times as much hot water is circulated compared to the amount of product circulated on the opposite side of the plates. 

Thermoduric, Thermophilic, andPsychrophihc Bacteria. Thermoduric bacteria survive but do not grow at pasteurization temperatures. They are largely non spore-forming, heat-resistant types that develop on surfaces of unclean equipment. These bacteria are determined by subjecting a sample to laboratory pasteurization and examining it by the agar plate method. 

This milk is finally heated by hot water up to the pasteurizing temperature of 75°C (or hotter for UHT milk) and held for a few seconds. 

SOD is more heat stable in milk than in purified preparations in milk it is stable at 71°C for 30 min but loses activity rapidly at even slightly higher temperatures. Slight variations in pasteurization temperature are therefore critical to the survival of SOD in heated milk products and may contribute to variations in the stability of milk to oxidative rancidity. 

Microbiological tests have indicated that penicillin G is stable to heat. Pasteurization temperatures and times commonly applied to milk and milk products are inadequate for inactivation of tlie antibiotic if it is present (26-29). At 71 C, a total of 1705 min was required to inactivate completely penicillin G in milk, whereas at boiling temperatures or above, all data indicated that a portion of tire penicillin activity in milk survived boiling for 60 min or autoclaving at 15 psi steam pressure for 15-30 min (26, 29). Milk from treated cows retained some of its antimicrobial activity even after conversion to dried skim milk powder (30). 

Cloud loss may also be prevented by enzymic destruction of low ester pectins prior to their precipitation as pectates. Commercial fungal PG preparations (AO, Al) or PG derived from yeast (A2) have been used successfully to stabilize cloud of unpasteurized PE active juice. As only the low ester pectins need be destroyed to prevent cloud loss, considerably less PG is required than PL (30). Cloud stabilization with pectinases permits production of cloud stable juices with lower pasteurization temperatures (AO). 

A quantitative objective measurement of citrus juice turbidity was used by Loeffler (15, 16) to show that pectic enzyme changes occurred so rapidly after the juice was reamed from the fruit that at least a partial coagulation of the cloud occurred before the juice could be screened, deaerated and heated to a pasteurization temperature. He showed that juice turbidity was increased by flash-pasteurization and also by homogenization of the juice before pasteurization. Loeffler (15, 16) presented data on turbidity of flash-pasteurized citrus juices (heat exposure for 16 to 18 sec) after storage at several temperatures. He found that "samples pasteurized at 918C (196°F) lost their cloud when stored at 35°F (95°F) but others pasteurized at 93-95°C (199-2038F) retained their cloud almost indefinitely". 

The purpose of pasteurization, as it is practiced in the domestic industry today, is to destroy spoilage organisms, inactivate enzymes, or both. Heating to temperatures of only 150°F (65.6°C) will destroy most spoilage organisms but some heat resistant molds may require pasteurization temperatures as high as 210°F (98.9°C) for control. 

These approaches have been reviewed extensively (Jameson, 1990 Ardo, 1997 Fenelon and Guinee, 1997 Fenelon, 2000). Various recommendations for the manufacture of reduced-fat cheeses with improved sensory and textural properties (Mistry et al., 1996 Johnson et al., 1998), (e.g., half-fat Cheddar prepared by homogenization of cream used to standardize the cheese milk) (Nair et al., 2000) the combined effects of increases in milk pasteurization temperature and pH at curd milling, and the use of selected starters and starter culture adjuncts (Guinee et al., 1999 Fenelon et al., 2002) ... 

Guinee, T.P., Fenelon, M.A., Mulholland, E.O., O Kennedy, B.T., O Brien, N., Reville, W.J. 1998. The influence of milk pasteurization temperature and pH at curd milling on the composition, texture and maturation of reduced-fat Cheddar cheese. Int. J. Dairy Technol. 51, 1-10. 

The principal questions concerning separation in a butter manufacturing facility are the choice of cream fat content and the choice of the separation technique, milk separation before or after pasteurization, temperature of separation, and regulation of the fat content. Separation of cream from milk is possible because of a difference in specific gravity between the fat and the hquid portion, or semm. Whether separation is accomplished by gravity or centrifugal methods, the result depends on this difference (48). 

The mix is next pasteurized to reduce the number of viable microorganisms to a level that is safe for human consumption, and homogenized to break the fat particles down into many small droplets. Figure 4.3 shows a flow diagram of a factory pasteurization and homogenization process. Much energy is needed to heat the mix up to the pasteurization temperature. To maximize the energy efficiency. 

In the second heating step, the mix is further heated with hot water in another section of the plate heat exchanger. At the end of this stage the mix must be hot enough to ensure that the pasteurization temperature is achieved after homogenization. However, the temperature should not exceed 85 °C in order to prevent denaturation of the milk proteins and to avoid the introduction of off-flavours (for example the taste of cooked milk). 

Generally a saprophyte although some forms act as parasites. Ceotrichum species are extremely common in nature but infrequently encountered in mushroom compost—unless it has been prepared directly on soil. Ceotrichum dwells in soils, cow dung, old straw, compost piles and rots some fmits and vegetables. In general, species of this genus are mesophilic thermophiles and are therefore sensitive to pasteurization temperatures. 

Discussion Tarsonemusm Aes are very small, 180-190 microns long, with pale brown, shining, oval bodies. They occasionally swarm in masses on mushroom caps but otherwise are rarely seen except by microscopic examination. Females produce an average of 22 eggs in a lifetime of 2-8 weeks. These mites cause a bright reddish-brown discoloration at the base of the mushroom stem and may cut the stem s mycelial connections. Known to survive normal compost pasteurization temperatures, they can carry a virus disease to Agaricus brunnescens. 

In bulk substrates such as compost or plain straw, nematodes can be found in great numbers. The high temperatures of Phase I conditioning would normally destroy them if it were not for the fact they migrate to the cooler outer shell of the compost pile. Phase II can eliminate nematodes but only if the entire compost is subjected to pasteurization temperatures. In a properly prepared and thoroughly pasteurized substrate, the mushroom mycelium consumes all free water and then feeds on the bacterial population. This creates a "bacteriostatic environment", which effectively limits nematode growth capabilties. In an uneven substrate with overly wet and dry areas, however, the nematode s ability to breed increases. Wet areas are particularly suitable for... 

Alkaline phosphatase Phosphatase enzymes are able to split specific phosporic acid esters into phosphoric acid and the related alcohols. Unlike most milk enzymes, it has a pH and temperature optima differing from physiological values pH of 9.8. The enzyme is destroyed by minimum pasteurization temperatures and therefore, a phosphatase test can be done to ensure proper pasteurization. 

The first sensitivity study assumes there is no control of the pasteurization parameters, i.e. of the pasteurization temperature. Tables 6 and 7 show the results found in this case. One can observe now there is an increase of LM content through the milk chain with consequences Cj to C4 possible. Formnately, analysis of LM content at cool storage reduces the initial load of LM in milk reaching the market. 

Pasteurizing varnishes pas-ch9- rlz-eg var-nish n. Varnishes for food containers which are capable of withstanding immersion in water at pasteurizing temperature for half an hour or more. Pasteurizing temperature is about 70°C, but food canners... 

---