High-temperature/short-time products

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 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. 

Neotame is an amino acid derivative and is, therefore, hydrolysed under conditions of low or high pH. Its stability will be a function of pH, temperature and time. The optimum pH range is similar to that for aspartame pH 3.2 1.5. In dry form neotame is stable. Products containing neotame and processed by high-temperature short-time (HTST) do not show significant losses to degradation of neotame (The NutraSweet Company, 2003). 

The extruder is a continuous high-temperature short-time reactor. Ingredients, moisture, temperature, pressure, and shear can interactively produce many Mail lard-type flavor compounds. As the extrudate exits the extruder, many of the volatile reaction products may be lost with steam since the extrudate passes from a zone of relatively high pressure within the extruder to atmospheric pressure. By controlling formulation variables, the extruder can serve as a useful tool to thermally produce volatile and nonvolatile compounds which make significant contributions to overall flavor. 

Starches have been used by the cereal and snack industries to achieve specific textures, e.g. increased crispness, especially in high-temperature, short-time processes.135,179 Snack market trends emphasize lower fat, including fried textures from baked products, high fiber and simpler processes. Starch can contribute significantly to the achievement of each of these targets. 

H. D. Stahl and T. H. Parliment, Formation of Maillard products in the proline-glucose model system high-temperature short-time kinetics, in Thermally Generated Flavors Maillard, Microwave, and Extrusion Processes, T. H. Parliment, M. J. Morello, and R. J. McGorrin (eds), American Chemical Society, Washington, DC, 1994, 251-262. 

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. 

Polyphosphates improve the sensory quality of many food products. They prevent the separation of butter fat and aqueous phases in evaporated milk, and the formation of gel in concentrated milk sterilized by high-temperature short-time (HTST). They also stabilize the fat emulsion in processed cheese by disrupting the casein micelles and thus enhance the hydrophobic interactions between lipids and casein. Polyphosphates are also used in meat processing for increasing the WHC and improving the texture of many cooked products. The mechanisms involved in different applications depend on the properties of the phosphates and the commodities, as well as the parameters of processing. 

These principles formed the basis for producing high quality carrots and potatoes by a process of biopolymer infusion followed by high temperature short time fluidized bed dehydration. Infused biopolymers was shown to penetrate intracellular spaces and cell walls and may contribute to reduced cell collapse in the dehydration process. Deposition of infused biopolymer within the cells was elucidated using a convalently bound complex of biopolymer and colored dye which was visible upon histochemical examinations under a microscope. The dehydration process was optimized with response surface methodology. The resulting products have excellent quality, high rehydration ratio and a puffed structure. 

The advantages of the high-temperature short-time aseptic canning process on quality retention in heat-processed products have been discussed by Luh and York (2). The importance of ripening process on quality of kiwifruit has been reported by... 

Process Conditions for High-Temperature, Short-Time Pneumatic Drying of Vegetables and Rehydration Characteristics of Products... 

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 kinetics of a Maillard reaction in a proline/gjucose model system were recently investigated by Stahl and Parliment at temperatures ranging between 160 C and 220°C and reaction times ranging between 0.25 min and 5 min. It was found that one compound, 5-acetyl-2,3-dihydro-l(H)-pyrrolizine, was the major product and formed by pseudo zero order Idnetics. It was determined that this compound had a relatively high energy of activation of 45 Kcal/mole (22). 

Extrusion cooking is a high temperature-short time process which is ideal for the production of flavor volatiles. However, due to the nature of this process there are many opportunities for these volatiles to be lost. This has led many researchers to study the formation and retention of volatiles during extrusion. This review will focus on the flavor related reactions which may occur during extrusion and their occurrence in various flours and due to the addition of reactive precursors. 

The inactivation of enzymes of fresh plant and animal tissue when the isolation procedure exceeds only a few minutes is essential. A common method used to inactivate enzymes is homogenization in methanol [12,13], This does, however, dilute the sample, decrease the polarity of an aqueous food slurry, and may interfere with later isolation methods. Thermal processes may also be employed if the product is a juice and may be rapidly passed through a high temperature short-time heat... 

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