Heat stability parameter

Elevated drum Evaluate thermal stability parameters of material temperatures (isothermal aging tests, SADT, etc.) reaching Self, Keep drums away from source of heat Accelerating Decomposition store at required temperature Temperature (SADT). CCPS G-15 CCPS G-22 CCPS G-29 CCPS G-30... 

Heat release function for source or sink, k Reaction kinetic function Gamma function Stability parameter see Eq. (40)... 

Processing parameters are also essential to consider, the most critical one normally being heating. Not all natural colours are equally heat stable. Colours like carmine and turmeric are generally considered to have excellent heat stability and can be used in, for example, UHT products. Red beet shows poor heat stability and tends to turn brownish during heating. The actual food matrix may also influence the heat stability. 

S-EB-S polymers are very compatible with paraffinic or naphthenic oils because of their lower midblock solubility parameter. As much as 200 parts of some of these oils can be added without bleedout. The articles have excellent heat stability, and the resistance of pigmented stocks to degradation from outdoor exposure is very good. Several compounds based on S-EB-S and S-B-S block polymers have been developed for special purposes. These include pharmaceutical goods, wire and cable coatings, and automotive applications (94). In pharmaceutical applications, the ability of some molded products to withstand steam sterilization as... 

Microbial lethality from steam sterilizatiem is a function of two parameters, temperature and time. The choice of a cycle is ultimately dependent upon the heat-stability of the product, the type of primary container, the knowledge of heat penetration into the product, the autoclave technology available, and the knowledge of the microbiological contamination prior to sterilization. However, the pharmacopoeias (particularly the USP) offer some sound general advice to the selection of criteria. 

D model gave center temperatures 2-3°C higher than the 1-D model, and a runaway reaction occurred at a slightly lower feed temperature than with the 1-D model. However, the 1-D model could be modified to be conservative by decreasing to 3kg/R to compensate for the higher reaction rate in the center. In any case, it is unlikely that a tubular reactor would be designed to operate close to the stability limit because of uncertainties in the kinetic and heat transfer parameters. 

The key requirement for PVC when it is eventually made to bum is the minimisation of the dark smoke levels emitted. Antimony, zinc and molybdenum compounds were incorporated as well as hydrated aluminium and magnesium fillers. The fire testing covered Limiting Oxygen Index, heat release parameters and smoke emission. General heat stability (integrity) and mechanical impact tests were also performed. 

Stability parameters Dimensionless ratio of height, Z, and the Monin-Obukhov stability length, L, which relates to the wind shear and temperature (buoyancy) effect. Thus, the term Z/L represents the relative importance of heat convection and mechanical turbulence. The Richardson number is also a dimensionless ratio of wind shear and buoyancy force. 

For fermented milks, for example yoghurt, acidophilus milk and bifido products, stabilisers are widely used in many countries to improve viscosity and prevent wheying-off. Several types of stabilisers (e.g. gelatins, starch, pectins, carrageenans and cellulose derivatives) are used. The choice depends on the characteristics wanted and the technology used. The main parameters to be considered in the choice of stabiliser for fermented milks are heat stability and sensitivity towards low pH and salts. The effect of stabilisers on the activity of starter cultures must also be taken into consideration (Kalab et al., 1983). 

The effect of the heating rate and the degree of transformation on such kineti c parameters as the activation energy and reaction order in the thermal degradation of phenyl- or pyridyl-carbamoylmethyl cellulose, indicated that the degradation reaction was very complex. Amidation of carboxymethyl-cellulose decreased the heat resistance and favoured the breaking of macro-molecular chains so that the supramolecular structure affected the heat stability of the derivative and the mechanism of thermal degradation. 

Application of Kinetic Data to Thermal Processing. In most studies on ttiermal inactivation of indicator enzymes including peroxidase, lipoxygenase, and LAHase, reaction rate constants and thermodynamic parameters have been determined on the assumption that thermal inactivation of the enzymes follows first order reaction kinetics (22). However, a deviation from first order kinetics is generally observed fipm the residual activity curve. This deviation has been explained by several mechanisms, including the formation of enzyme aggregate with different heat stabilities, the presence of heat stable and labile enzymes, and the series type inactivation kinetics. 

Investigate and determine thermal parameters involving conditions under which heat transfer takes place and an accurate value of the heat transfer surface area. Additionally, a review of the process is required for thermal stability (see Chapter 6). 

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