Optimizing Thermal Process for Canned White Beans in Water Cascading Retorts

Based on thermal degradation kinetics and heat transfer expressed as the Ball formula method, a simplified approach was used to optimize sterilization processes for thermal softening of white beans (Phaseolus vulgaris, subsp. nanus Metz., variety Manteca de Leon) Constant retort profiles in a still and end-over-end rotary water cascading retort (Barriquand Steriflow) were used. Quality attributes of beans processed at the optimum were evaluated by a trained taste panel and by a tenderometer. Both approaches could distinguish (P<0.01) between attributes of products from optimal rotary and still processes. End-over-end rotation resulted in faster heat penetration and better quality retention of beans. Texture of white beans processed at 4° or 8°C from the optimal temperature could be distinguished (P<0.01) by the sensory panel and by the tenderometer.     

Immobilized α-amylase from Bacillus licheniformis: a potential enzymic time—temperature integrator for thermal processing

Biphasic and nth-order models were tested as to their usefulness to fit experimental inactivation data of Bacillus licheniformis α-amylase, immobilized on glass beads, and were discussed with respect to their suitability to characterize the considered enzymic system as a time—temperature integrator (TTI) to evaluate heat processes. Both isothermal and non-isothermal inactivation experiments were carried out. Model (kinetic) parameters (rate constant k, activation energy E_A and reaction order n) were estimated using a non-linear regression procedure. The results obtained, especially the activation energy of about 293 kJ mole^–1, indicated a potential use of this system as a TTI for heating processes in the temperature range of 96–108°C.     

KINETICS of THERMAL SOFTENING of WHITE BEANS EVALUATED BY A SENSORY PANEL and the FMC TENDEROMETER

The temperature dependence of the rate index of thermal softening of white beans ( Phaseolus vulgaris , subsp. nanus Metz. variety Manteca de Leon ) was determined within the temperature range of 90C to 122C using an industrial FMC tenderometer and a trained sensory panel. Based on sensorial results a first order reaction was assumed, whereas the tenderometer values were described by a biphasic model. Using a multiple linear regression analysis on the sensorial data, the activation energy for the heat induced firmness degradation of beans was calculated as 130.8 kJ/mole. Activation energies of both phases of the biphasic model were obtained by a two-step linear regression on the tenderometer data. Activation energies of both phases were equal, namely 105.1 kJ/mole.     

Validation of a time-temperature-integrator for thermal processing of foods under pasteurization conditions

In this work, a general theory for the development of a Time Temperature Integrator, TTI-system, is outlined. A z-value (or activation energy) of the TTI-system equal to that of target index is crucial for the usefulness of a system to monitor the impact of thermal processes on foods. The proposed TTI, namely the heat-stable fraction of peroxidase covalently immobilized on porous glass beads in dodecane, can be used to indicate the intensity of a delivered pasteurization process when a z-value of 10°C is used for calculating the lethality. Lethalities read from the bio-indicator showed excellent agreement with those integrated from the measured time-temperature data.     

THEORETICAL CONSIDERATIONS ON DESIGN of MULTICOMPONENT TIME TEMPERATURE INTEGRATORS IN EVALUATION of THERMAL PROCESSES

Recently, the use of Time Temperature Integrators (TTIs) as an alternative means of process evaluation, besides in situ process monitoring and the physical-mathematical method, has received a lot of attention. the stringent requirement to which an adequate functioning TTI should respond, i.e. , the temperature dependence of reaction rate constants for the monitored target quality attribute and the TTI shall be identical, is hard to realize in practice. Therefore, multicomponent TTIs have been suggested to evaluate the integrated impact of time and temperature on a target quality attribute. These monitoring devices consist of a number of temperature sensitive units, each with its own response of reaction rates to temperature. the question how from the combined reading of these individual systems, the impact of the heating process on a target quality parameter can be predicted has not yet been answered.
In this theoretical study, we critically consider the restrictions of two interpolation methods in determining the impact on a target quality attribute from the reading of three other temperature sensitive systems. Possibilities of the 'Equivalent Point Method'and a polynomial expression as interpolation method are tested. Success of these transformations depends on kinetic characteristics of the components in the multicomponent TTI system and the actual product temperature history. Since only limited information is available on the product temperature     

Immobilized Peroxidase: A Potential Bioindicator for Evaluation of Thermal Processes

The heat-stable fraction of covalently immobilized peroxidase on/in porous glass beads in an environment of dodecane was studied as a bioindicator for evaluation of thermal processes under conditions of pasteurization. The verified bioindicator had a z value of 10.1°C and a Dref (at 70°C) of 22 min. At processing temperatures of 70°C and 80°C, the lethalities (F)_bio as read from the bioindicator agreed very well with the target Ft^10.0 values calculated from the time temperature data according to the general method.     

氯盐浸泡的水泥基材料的表面氯离子浓度

水泥基材料的表面氯离子浓度(cs)是Fick's第二定律寿命预测模型的1个重要参数,它通过将Fick's第二定律与氯离子浓度分布拟合而得到.当水泥基材料浸泡在一定浓度的氯盐溶液中时,水泥基材料的cs和浸泡溶液的氯离子浓度(c)之间的关系仍未得到很好的理解.一些发表的文献表明cs要高于c,Nagataki将其称为浓缩现象...     

Thermostability of Soluble and Immobilized Horseradish Peroxidase

Thermal inactivation kinetics of soluble horseradish peroxidase and the enzyme covalently immobilized onto glass beads were studied in phosphate buffer and organic solvents in a temperature range of 65° to 98°C. The z value of the heat-stable fraction of peroxidase was changed from 26.3°C to 14.1°C by the method of enzyme immobilization. Further, the z value of 14.1°C of the immobilized peroxidase was lowered to 11.1°C using an organic solvent in order to modify the environment of the enzyme.