The Use of Tin Oxide Coating and High Frequency Power to Minimize Corrosion in Ohimc Cooking

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dc.contributor.advisor Farid, M en
dc.contributor.author Wang, Ruogu en
dc.date.accessioned 2013-11-07T21:39:57Z en
dc.date.issued 2013 en
dc.identifier.uri http://hdl.handle.net/2292/21057 en
dc.description Full text is available to authenticated members of The University of Auckland only. en
dc.description.abstract Ohmic heating is an advanced thermal process, wherein the electrical energy is converted into heat and causes efficient rising of the interior temperature of the food. Previous research has shown that food can be cooked fast and uniformly by combined ohmic and conventional cooking. However, pitting corrosion, occurred on the electrode plates after plate/ohmic cooking, influenced the safety and the quality of food product, thus slowed down the commercialisation of plate/ohmic cooker. Corrosion is a complex process which involves several parameters. Recently, the mechanism of corrosion in plate/ohmic cooking has been researched in order to solve the problem. Various metals and alloys were applied as electrodes and tested to understand the corrosion. This research used a sol-gel dip coating route to coat different thickness (100 nm, 250 nm, 500 nm, 750 nm and 1000 nm) of tin oxide layers on stainless steel 316L substrates. All coated plates were used as electrodes in 50 Hz and 10 kHz plate/ohmic cooking to determine the effect of the coating layer and high frequency power on corrosion reduction. Experimental studies of related food qualities and safety of cooked meat patties were also conducted in this research. Uncoated stainless steel 316L plates were used as references in all experimental works. Electrical resistance of tin oxide coating layer was measured at different coating thickness. It is shown that the electrical resistance of tin oxide coating layers increases with its thickness linearly. Therefore, the cooking times of meat patties were only slightly affected by the electrical resistance of tin oxide coating layer. More specifically, a higher coating thickness of tin oxide layer could result in a longer cooking time. Gravimetric analyses showed that mechanical properties, moisture, crude fat and solid content of meat patties cooked by different plates in conventional and plate/ohmic cooking are similar. However, moving from conventional to plate/ohmic cooking, significant metal ions are transferred to the meat patties even at high frequency of 10 kHz. More importantly, iron, nickel, chromium and tin concentrations in the 120 g plate/ohmic cooked meat patty are found acceptable with regard of food safety. IIExceptional corrosion resistances were found by visual observation of the corroded tin oxide coated plates. The corrosion of coated tin oxide plates decreased effectively at 10 kHz plate/ohmic cooking compared to the stainless steel 316L plate at the same frequency. Moreover, comparison between 1000 nm tin oxide coated plate and an uncoated stainless steel plate showed that, the corrosion was reduced by applying a tin oxide coating layer even when low frequency of 50 Hz was applied. The corrosion rate of electrodes and ion transfer rates of cooked meat patties provided evidence that, the use of tin oxide coating layer and high frequency power could minimize corrosion in plate/ohmic cooking. en
dc.publisher ResearchSpace@Auckland en
dc.relation.ispartof Masters Thesis - University of Auckland en
dc.rights Items in ResearchSpace are protected by copyright, with all rights reserved, unless otherwise indicated. Previously published items are made available in accordance with the copyright policy of the publisher. en
dc.rights Restricted Item. Available to authenticated members of The University of Auckland. en
dc.rights.uri https://researchspace.auckland.ac.nz/docs/uoa-docs/rights.htm en
dc.title The Use of Tin Oxide Coating and High Frequency Power to Minimize Corrosion in Ohimc Cooking en
dc.type Thesis en
thesis.degree.grantor The University of Auckland en
thesis.degree.level Masters en
dc.rights.holder Copyright: The Author en
pubs.elements-id 408294 en
pubs.record-created-at-source-date 2013-11-08 en


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