Papers by Pitiya KAMONPATANA
ACS Omega
Agroindustrial wastes are renewable sources and the most promising sustainable alternative to lig... more Agroindustrial wastes are renewable sources and the most promising sustainable alternative to lignocellulosic biomass for cellulose production. This study assessed the electrothermal pretreatment of rambutan peel (RP) for producing cellulose fibers. The pretreatment was carried out by Ohmic heating at a solid-to-liquid ratio of 1:10 (w/v) in a water/ethanol (1:1, v/ v) mixture as the electrical transmission medium at 60 ± 1°C for different holding times (15, 30, and 60 min). Ohmic heating did not significantly influence the total fiber yield for the various holding times. However, the compositions of the samples in terms of extractives, lignin, hemicellulose, and α-cellulose content were significantly influenced. In addition, the electrothermal pretreatment method reduced the bleaching time of RP by 25%. The pretreated fibers were thermally stable up to 240°C. Ohmic heating pretreatment times of 15 and 30 min were found most promising, reducing the required bleaching chemicals and increasing the α-cellulose yield. The pretreated bleached cellulose fibers had similar properties to nontreated bleached fibers and could be efficiently processed into stable gels of strong shear-thinning behavior with potential application as rheology modifiers in food products. Our results demonstrate that rambutan peel could serve as a promising sustainable alternative to woody biomass for cellulose production. Ohmic heating meets the requirements for industrial applications as it is eco-friendly, improves the efficiency and energy consumption in fiber processing, and could as well be included in the processing of similar food wastes.
To accomplish continuous flow ohmic heating of a low-acid food product, sufficient heat treatment... more To accomplish continuous flow ohmic heating of a low-acid food product, sufficient heat treatment needs to be delivered to the slowest heating particle at the outlet of the holding section. This research was aimed at developing mathematical models for sterilization of a multicomponent food in a pilot-scale ohmic heater and verifying microbial inactivation by inoculated particle methods. Thermal verification of the mathematical model showed good agreement between calculated and experimental fluid temperatures (P>0.05) at heater and holding tube exits. In addition, a microbiological verification test was conducted using chicken-alginate particles inoculated with spores of Clostridium sporogenes. The test indicated the absence of viable microorganisms at the target treatment and its presence for a sub-target treatment, thereby verifying model predictions.
Foods, 2021
The microwave oven has become a standard appliance to reheat or cook meals in households and conv... more The microwave oven has become a standard appliance to reheat or cook meals in households and convenience stores. However, the main problem of microwave heating is the non-uniform temperature distribution, which may affect food quality and health safety. A three-dimensional mathematical model was developed to simulate the temperature distribution of four ready-to-eat sausages in a plastic package in a stationary versus a rotating microwave oven, and the model was validated experimentally. COMSOL software was applied to predict sausage temperatures at different orientations for the stationary microwave model, whereas COMSOL and COMSOL in combination with MATLAB software were used for a rotating microwave model. A sausage orientation at 135° with the waveguide was similar to that using the rotating microwave model regarding uniform thermal and electric field distributions. Both rotating models provided good agreement between the predicted and actual values and had greater precision tha...
To ensure sterility of a solid-liquid mixture processed in continuous-flow ohmic systems, the slo... more To ensure sterility of a solid-liquid mixture processed in continuous-flow ohmic systems, the slowestheating solid particle needs to receive sufficient heat treatment at the outlet of the holding section. We describe herein, the development of a mathematical model for solid-liquid mixtures in a commercial ohmic heater with electric field oriented perpendicular to the flow. The fastest moving particle velocity was identified using over 299 particles and a radio-frequency identification technique, and used as an input to the model for the worst-case heating scenario. Thermal verification was conducted by comparing predicted and measured fluid temperatures at heater and hold tube outlets; the model showed good agreement between calculated and experimental fluid temperatures (P > 0.05) with a maximum error of 0.4°C. The model predicted a hold tube length of 15.85 m at 134.0°C process temperature to achieve a target lethal effect at the cold spot of the slowest-heating particle. Using this length of hold tube, microbiological tests were conducted using at least 299 chicken/alginate particles inoculated with Clostridium sporogenes spores per run. These tests showed the absence of viable microorganisms at the target treatment and positive growth when temperatures were below target, thereby verifying model predictions.
Reference Module in Food Science
Food and Bioprocess Technology
The price of rice bran oil depends on the amounts of contained bioactive compounds especially ory... more The price of rice bran oil depends on the amounts of contained bioactive compounds especially oryzanol and phytosterols. The oryzanol content of rice bran oil under ohmic heating optimized at 70 V/cm, 90 °C for 3 min (27,580.75 ± 916.58 mg/kg) was higher than the control (24,908.57 ± 19.87 mg/kg). Ethanol-to-water ratio (p ≤ 0.000), medium-to-rice bran ratio (p ≤ 0.002), and electric field (p ≤ 0.028) all statistically significantly affected oryzanol content. Using water medium at low electric field (70 V/cm) produced the highest oryzanol content, while a high medium-to-rice bran ratio (1:1) resulted in the highest oryzanol content due to rapid temperature increase. Ohmic heating reduced acid value and free fatty acid content of rice bran oil and hence extended its shelf life. Ohmic heating under pressure (1 bar) was applied to elevate the boiling point and prolong the holding time, thereby obtaining higher oryzanol content (24,758.11 ± 48.96 mg/kg) than in non-pressurized rice bran oil (21,170.93 ± 42.72 mg/kg) (p ≤ 0.05). Conductivity of the medium and holding time positively correlated with oryzanol content whereas temperature had a negative correlation. Ohmic heating extraction efficiency increased with more water-soluble bioactive compounds ranking from phenolics, oryzanol, and phytosterols.
Key Engineering Materials
This study was aimed to develop conductive packaging for ohmic heating. Polypropylene (PP) was mi... more This study was aimed to develop conductive packaging for ohmic heating. Polypropylene (PP) was mixed with conductive material (CM) in the ratios of 70:30 (CM30), 75:25 (CM25), and 80:20 (CM20) (w/w), then the conductive bottles were developed using extrusion blow molding process. The bottles were suspended in different sodium sulfate (Na2SO4) solutions (0.2, 0.3, and 0.5% w/w) as a transmitting current medium for ohmic heating and heated for 8 min. The CM30 and CM 25 had the highest electrical conductivity compared to the CM20, however the CM20 exhibited best processability, hence it was selected to be used for ohmic heating of orange juice. Different concentrations of Na2SO4 solutions had the effects on ohmic heating. The CM20 bottle suspended in 0.2% Na2SO4 solution resulted in the most uniform heating and suitable for ohmic processing of orange juice. The new conductive bottles developed could potentially be used for beverage processing by ohmic heating.
Journal of Food Engineering
Journal of biotechnology, Jan 10, 2018
Suspensions of the model microalga Chlorella sp. TISTR 8990 were pretreated by ohmic heating to f... more Suspensions of the model microalga Chlorella sp. TISTR 8990 were pretreated by ohmic heating to facilitate release of lipids from the cells in subsequent extraction and lipase-mediated transesterification to biodiesel. After ohmic pretreatment, the moist biomass was suspended in a system of water, hexane, methanol and immobilized lipase for extraction of lipids and simultaneous conversion to biodiesel. The ohmic pretreatment was optimized using an experimental design based on Taguchi method to provide treated biomass that maximized the biodiesel yield in subsequent extraction-transesterification operation. The experimental factors were the frequency of electric current (5-10 Hz), the processing temperature (50-70 °C), the algal biomass concentration in the slurry (algal fresh weight to water mass ratio of 1-3) and the incubation time (1-3 min). Extraction-transesterification of the pretreated biomass was carried out at 40 °C for 24 h using a reaction systems of a fixed composition (...
Journal of Food Science
Ohmic heating through an electrically conductive food package is a new approach to heat the food ... more Ohmic heating through an electrically conductive food package is a new approach to heat the food and its package as a whole after packing to avoid post-process contamination and to serve consumer needs for convenience. This process has been successfully completed using polymer film integrated with an electrically conductive film to form a conductive package. Orange juice packed in the conductive package surrounded with a conductive medium was pasteurized in an ohmic heater. A mathematical model was developed to simulate the temperature distribution within the package and its surroundings. A 3-D thermal-electric model showed heating uniformity inside the food package while the hot zone appeared in the orange juice adjacent to the conductive film. The accuracy of the model was determined by comparing the experimental results with the simulated temperature and current drawn; the model showed good agreement between the actual and simulated results. An inoculated pack study using Escherichia coli O157:H7 indicated negative growth of viable microorganisms at the target and over target lethal process temperatures, whereas the microorganism was present in the under target temperature treatment. Consequently, our developed ohmic heating system with conductive packaging offers potential for producing safe food.
Engineering Properties of Foods, Fourth Edition, 2014
Engineering properties of foods, 2005
Page 491. 10 Electrical Conductivity of Foods SUDHIR K. SASTRY The Ohio State University, Columbu... more Page 491. 10 Electrical Conductivity of Foods SUDHIR K. SASTRY The Ohio State University, Columbus, Ohio I. INTRODUCTION Interest in the electrical conductivity of foods, once primarily restricted to various testing applications ...
LWT
Abstract Listeria monocytogenes contamination of processed sausage occurs primarily after cooking... more Abstract Listeria monocytogenes contamination of processed sausage occurs primarily after cooking and during packaging, causing significant annual economic loss throughout the industry. Post pasteurization ohmic heating of vacuum packed sausages was proposed for effective post packaging decontamination. Ohmic heating of 75 °C for 30 s (OH) was investigated and compared to conventional heating at 75 °C for 30 s (CT (30 s)) and for 2 min (CT (2 min)) regarding L. monocytogenes inactivation, product properties, and sensorial attributes. OH, having a shorter come up time, completely inactivated L. monocytogenes with more than a 5-log reduction, whereas CT (30 s) and CT (2 min) achieved 3- and 4-log reductions, respectively. Ohmic heating did not statistically change sausage chemical composition, pH, lipid oxidation, cooking loss, or water holding capacity and only minimally altered color and texture. Regarding CT (2 min), the longer heating time increased cooking loss and decreased tenderness. Despite color and texture changes after both ohmic and conventional heating being detected by instrumental analysis, consumers were unable to detect any sensory differences between the methods. In conclusion, OH shows potential in sausage production, for both food safety and process efficiency, with minimal effect on sausage quality.
Uploads
Papers by Pitiya KAMONPATANA