Kinetics of flavour and aroma changes in thermally processed cupuaçu (Theobroma grandiflorum) pulp

Changes in `fresh' and `cooked-notes' during thermal treatment of cupuacËu (Theobroma grandi¯orum) pulp were evaluated and modelled. Isothermal experiments in the temperature range of 70±98°C were carried out and a non-linear regression was performed to all data to estimate kinetic parameters. `Fresh' and `cooked-notes' change followed simple ®rst-order (Ea=78±82kJ mol ÿ1, z =30±31°C) and reversible ®rst order (Ea=80±85kJ mol ÿ1) kinetics, respectively. Although `cookednotes' were linearly correlated with `fresh-notes' (R2=0.99), the former was a better indicator for quality degradation. These results are useful to design pasteurisation processes while minimising sensory changes

Dense phase carbon dioxide : food and pharmaceutical applications

Indexxii, 512 hlm. : ill. ; 27 cm

Food treatment with high pressure carbon dioxide: S. cerevisiae inactivation kinetics expressed as a function of CO2 solubility

Experimental survival curves of Saccharomyces cerevisiae cells exposed to high pressure carbon dioxide (HPCD) treatments under several constant temperatures (35, 40 and 50 ◦C), pressures (7.5, 10.0 and 13.0MPa) and suspended in distilled water with different sodium phosphate monobasic buffer concentrations (0.02, 0.10, 0.20 and 0.40M) were obtained. The Peleg model was applied to the isobaric and isothermal conditions described by the power law equation log[S(t)] =−btn, where S(t) is the momentary survival ratio and ‘b’ and ‘n’ are the rate and the shape parameters, respectively. The values of the coefficients ‘b’ and ‘n’ were calculated for each experiment at fixed pressure and temperature. For each suspending medium the power law model was proposed to describe the combined effects of pressure and temperature. Taking into account the CO2 solubility as a function of the sodium phosphate monobasic concentration, ‘b’ and ‘n’ were correlated to the CO2 solubility values and temperature. An equation was proposed for ‘b’ as a function of CO2 solubility and temperature while ‘n’ was a weak function of temperature. The resulting equation was much simpler that the one obtained correlating the microbial inactivation to pressure and temperature and, more important, it was independent of the suspending medium. The results indicate that the coupling of carbon dioxide solubility, also predicted with commercial software, and the use of inactivation models referred to solubility and temperature may provide a powerful instrument for the interpretation of microbial inactivation experiments and for the design of HPCD processes and equipments