High-temperature short-time pasteurization

High Temperature—Short Time Pasteurizers. The principal continuous-flow process is the high temperature—short time (HTST) method. The product is heated to at least 72°C and held at that temperature for not less than 15 s. Other features are similar to the batch hoi ding method. 

The introduction of high temperature-short time pasteurization of mix has emphasized the need for hydrocolloids which are quick-soluble and do not require heat for complete activation. 

The waste milk in dairy wastewaters mostly comes from start-up and shut-down operations performed in the high-temperature, short-time pasteurization process. This waste is pure milk raw material mixed with water. Another wastewater of the dairy sector originates from equipment and tank-cleaning wastewaters. These waste streams contain waste milk and sanitary cleaners that are the principal waste constituents of dairy wastewater. Over time, milk waste degrades to form corrosive lactic and formic acids. Approximately 90% of a dairy s wastewater load is milk. 

HTST High-temperature short-time pasteurization... 

High-temperature short-time pasteurization of milk at 88 degrees Celsius for one second is as effective in killing pathogenic bacteria as conventional pasteurization at 63 degrees Celsius for thirty minutes and is less damt ing to the value of the food. 

For the production of ice cream, the mixture of components is subjected to high-temperature short-time pasteurization (80-85 °C, 20-30 s), high-pressure homogenization (150-200 bar) and cooling to ca. 5 °C. Air is then mixed into the mixture (60-100 vol%) while it is frozen at temperatures of up to —10 °C and then hardened. The freezers used are mainly continuously working systems furnished with coolants which evaporate at —30 °C to —40 °C. The process is controlled in such a way that the core temperature of the ice cream production is ca. —18 °C. 

Flash Pasteurization See High-Temperature Short-Time Pasteurization. 

HTST high temperature short-time pasteurization Ltd. Limited... 

Pasteurization may be carried out by batch- or continuous-flow processes. In the batch process, each particle of milk must be heated to at least 63°C and held continuously at this temperature for at least 30 min. In the continuous process, milk is heated to at least 72°C for at least 15 s ia what is known as high temperature—short time (HTST) pasteurization, the primary method used for fluid milk. For milk products having a fat content above that of milk or that contain added sweeteners, 66°C is requited for the batch process and 75°C for the HTST process. For either method, foUowiag pasteurization the product should be cooled quickly to <7.2° C. Time—temperature relationships have been estabHshed for other products including ice cream mix, which is heated to 78°C for 15 s, and eggnog, which must be pasteurized at 69°C for 30 min or 80°C for 25 s. 

High-temperature short time (HTST) pasteurization is used in a majority of plants in the United States. HTST pasteurization is conducted at temperatures > 72 °C and holding time > 15 s in the United States (FDA, 2009). Milk may also be pasteurized using ultrahigh temperature (UHT) pasteurization. 

Compatible with protein-rich beverages (e.g., milk-based soy-based) treated with high-temperature short-time (HTST) pasteurization. However, may be issues with flocculation, thickening, or sedimentation due to Ca-protein interactions when subjected to ultra-high temperature (UHT) heat treatment... 

Edmondson et al (1971), who studied the enrichment of whole milk with iron, found that ferrous compounds normally caused a definite oxidized flavor when added before pasteurization. Aeration before addition of the iron reduced the off-flavor. The authors recommended the addition of ferric ammonium citrate followed by pasteurization at 81 °C. Kurtz et al. (1973) reported that iron salts can be added in amounts equivalent to 20 mg iron per liter of skim milk with no adverse flavor effects when iron-fortified dry milk is reconstituted to skim milk or used in the preparation of 2% milk. Hegenauer et al. (1979A) reported that emulsification of milk fat prior to fortification greatly reduced lipid peroxidation by all metal complexes. These researchers (Hegenauer et al. 1979B) concluded that chelated iron and copper should be added after homogenization but before pasteurization by a high-temperature-short-time process. 

Citrus juices that are pasteurized at the lower temperatures, 65-66°C, can undergo clarification, i.e., a process of separation that results in a lower layer of liquid and sediment and an upper layer of clear liquid. This process is brought about by the natural enzyme, pectinesterase, that occurs in citrus fruits. Studies have shown that processing of the juice at temperatures of 170-210°F (76.7-99°C) for a fraction of a second to 40 seconds will destroy the pectinesterase activity in citrus juices (7-10). The temperature necessary to stabilize the juice is pH dependent. Juices at higher pH require higher temperatures for stabilization. With the new high-temperature short-time techniques and equipment, stabilization can usually be effected in a fraction of a second. Flash pasteurization can be accomplished in either a plate-type or a tube-type heat exchanger. 

High-temperature short-time (HTST) treatment (72°C x 15 s) of milk almost completely inactivates the enzyme (Luhtala and Antila, 1968 Andrews et al., 1987 Farkye et al., 1995) so that little if any lipolysis caused by milk lipase occurs in pasteurised milk (Downey, 1974). Somewhat higher temperatures are required for cream pasteurization because of the protective effect of the fat (Nilsson and Willart, 1961 Downey and Andrews, 1966). However, some workers have reported that a more severe heat treatment, [e.g., 79°C x 20 s, (Shipe and Senyk, 1981) or 85°C x 10 s (Driessen, 1987)] is required to inactivate completely milk lipase. 

To maintain cloud stability in fruit juices, high-temperature-short-time (HTST) pasteurization is used to deactivate pectolytic enzymes. Pectin is a protective colloid that helps to keep insoluble particles in suspension. Cloudiness is required in commercial products to provide a desirable appearance. The destruction of the high levels of pectin-esterase during the production of tomato juice and puree is of vital importance. The pectinesterase will act quite rapidly once the tomato is broken. In the so-called hot-break method, the tomatoes are broken up at high temperature so that the pectic enzymes are destroyed instantaneously. 

Pasteurization requires considerably less thermal input than does sterilization. Therefore, the thermal losses during pasteurization processing are quite low. However, oxidative losses can be high if care is not taken to deaerate and if high-temperature-short-time (HTST) conditions are not used (80). 

HTST. Abbreviation for high-temperature short-time, refers to processes such as pasteurization, sterilization, etc. 

The inhibition of malo-lactic fermentation can be obtained by SO2 (/w30 mg/liter), maintainance of storage temperature at less than 18°C and adjustment of pH to at least below 3.3. Killing or removing the bacteria from wine is a more definite step to stabilize wine against malo-lactic fermentation. Pasteurization and particularly HTST treatment (high temperature, short time -98 C for one second - with rapid cooling) is often used. Sterile filtration has also been used with 0.45 (un membrane filters. 

Pasteurization is made by a plate heat exchanger that manages 25000 litres per hour and it works 12 hours at day, 350 days/year. In accordance with Commission Regulation (EC) n° 2074/2005, 72°C and 15 seconds is required for High Temperature Short Time (HTST) pasteurization. Tables 1 to 3 show also relevant data associated with pasteurization stage, i.e. conditions, LM reduction and control respectively. In order to assure safety and quality parameters, company analyzes three packages per batch of the elaborated product while they are in the storage cold room. Then,... 

High-temperature short-time (HTST) pasteurization Process in which milk is heated to 71.6°C for at least 15 s. 

High Frequency of Recombination (Hfr) Strain A strain of bacteria in which the F plasmid is incorporated into the bacterial chromosome. High-Temperature Short-Time (HTST) Pasteurization Process in which milk is heated to 71.6°C for at least 15 seconds. Known also as Flash Pasteurization. 

The analysis of the results of this base case (Table 6) as compared with the initial content for HMF, DN and Saccharomyces (Table 2) shows that HMF content, in average, is not affected due to the short time of the pasteurization stage. A similar conclusion had been obtained by Domenech et al 2008 and Tosi et al., 2008 what concerns HMF content evolution, stating that pasteurization stage is not relevant for the HMF content. On the contrary. Diastase (DN) is influenced by a high temperature and Saccharomyces by a low time and temperature. Therefore, the role of the controls of these parameters is relevant, and this situation is explored further in the following section where the results of a sensitivity analysis are shown. 

Fig. 10.15. Heating of milk. 1-3 Pasteurization 1 high temperature treatment, 2 short time and 3 long time heat treatment 4 and 5 UHT treatment 4 indirect and 5 direct 6 sterilization, a Killing pathogenic microorganisms Tubercle bacilli as labelling organism), b c inactivation of alkaline/acid phosphatase, d, d2, d denat-uration (5, 40, 100%) of whey proteins, e casein heat coagulation,/ start of milk browning...

Chnngnt in Qunlity Since heat is less than boifng temperature and for a short time, the quality of the food is maintained. Foods which are pasteurized indude those whose flevor and appearance may be adversaly affected by high temperatures. 

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