High hydrostatic pressure (hhp) applications in food science: a study on compression heating, microbial inactivation kinetics, pulsed pressure and high pressure carbon dioxide treatments

Buzrul, Sencer
In this study the action of high hydrostatic pressure (HHP) on compression heating of liquid foods and pressure transmitting fluids, inactivation of Escherichia coli and Listeria innocua in different food media (milk and fruit juices), pulsed pressure and high pressure carbon dioxide treatments was investigated. The experimental results in this study allowed pointing out some important results: (i) The thermal effects of compression should be taken into account when HHP pasteurization processes are developed. Initial temperature of the food product and compression rate should carefully be selected in order to compensate the compression heating; (ii) The HHP inactivation kinetics need not follow traditional first-order kinetics, hence alternative inactivation models are ought to be found. Weibull model can be used for HHP inactivation kinetics of microorganisms; (iii) The pulsed pressure treatment could be an alternative to continuous HHP, but optimization should be done between the pulse holding time, the number of pulses and the pressure level to reach the desirable number of log-reduction of microorganisms (E. coli and L. innocua) compatible with an industrial application; (iv) The storage duration and storage temperature after HHP treatment should carefully be optimized to increase the safety of HHP treated fruit juices since the growth of injured microorganisms can be avoided during storage; (v) The high pressure carbon dioxide (HPCD) treatment in combination with pulsed pressure can be an efficient way to inactivate the microorganisms in skim milk and to reduce the maximum pressure level for the desired log-reduction.


Supercritical carbon dioxide extraction of apricot kernel oil
Özkal, Sami Gökhan; Yener, Meryem Esra; Department of Food Engineering (2004)
The purpose of this research was to determine the solubility of apricot (Prunus armeniaca L.) oil in supercritical carbon dioxide (SC-CO2), effects of parameters (particle size, solvent flow rate, pressure, temperature and co-solvent (ethanol) concentration) on extraction yield and to investigate the possibility of fractionation. Solubility, increased with pressure and increased with temperature above the crossover pressure, which was found between 200 and 300 bar, and decreased with temperature below the c...
Modeling of tempering of frozen potato puree by microwave, infrared assisted microwave and ohmic heating methods
Seyhun, Nadide; Şümnü, Servet Gülüm; Department of Food Engineering (2008)
The main purpose of this thesis is to develop a model that can predict the temperature profile inside a frozen food sample during microwave tempering and infrared assisted microwave tempering processes. Another goal of the study is to compare the tempering time of frozen foods by using microwave, infrared assisted microwave, and ohmic heating methods. Frozen potato puree was used as the food sample for all studies. Three different microwave power levels (30%, 40%, and 50%) were used for microwave tempering ...
Inactivation of peroxidase and lipoxygenase in green beans, peas and carrots by a combination of high hydrostatic pressure and mild heat treatment
Akyol, Çağdaş; Bayındırlı, Alev; Department of Food Engineering (2004)
In this study, the efficiency of high-pressure treatment (HHP, 250 - 450 MPa) with the combination of heat treatment (20 - 70oC) on peroxidase (POD) and lipoxygenase (LOX) inactivation in green beans, green peas and carrots was investigated for blanching purposes. Two steps treatments were also performed by pressurization at 250 MPa at 20°C for 15- 60 min and then by water blanching at 40-70°C. For green beans, 25 % residual activity was obtained by water blanching at 50°C for 15 min after the pressurizatio...
Optimization of microwave-halogen lamp baking of bread
Demirekler, Pınar; Şümnü, Servet Gülüm; Department of Food Engineering (2004)
The main objective of this study was to optimize the processing conditions of breads baked in halogen lamp-microwave combination oven by using response surface methodology. It was also aimed to construct neural network models for the prediction of quality parameters of bread as a function of processing conditions. Different baking time and power combinations were used in order to find the optimum baking conditions of bread in halogen lamp-microwave combination oven. The independent variables were the baking...
Recovery of strawberry aroma compounds by pervaporation
İşçi, Aslı; Şahin, Serpil; Department of Food Engineering (2004)
Pervaporation is a selective membrane technique in which a liquid feed mixture is separated by means of partial vaporization through a non-porous perm-selective membrane. This method can be used for the recovery of heat sensitive aroma compounds to avoid them from thermal damage in beverage industries. The main objective of this study was to determine the effects of feed temperature (30, 40, 50°C), composition (different model solutions, strawberry essence), concentration (50, 100, 150 ppm) and permeate pre...
Citation Formats
S. Buzrul, “High hydrostatic pressure (hhp) applications in food science: a study on compression heating, microbial inactivation kinetics, pulsed pressure and high pressure carbon dioxide treatments,” Ph.D. - Doctoral Program, Middle East Technical University, 2008.