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Mechanisms of sunflower oil transforming into forced thermal oxidation processes

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dc.contributor.author STURZA, Rodica
dc.contributor.author DRUŢĂ, Raisa
dc.contributor.author COVACI, Ecaterina
dc.contributor.author DUCA, Gheorghe
dc.contributor.author SUBOTIN, Iurie
dc.date.accessioned 2020-10-08T07:21:18Z
dc.date.available 2020-10-08T07:21:18Z
dc.date.issued 2020
dc.identifier.citation STURZA, Rodica, DRUŢĂ, Raisa, COVACI, Ecaterina et al. Mechanisms of sunflower oil transforming into forced thermal oxidation processes. In: Journal of Engineering Science. 2020, Vol. 27(3), pp. 239-251. ISSN 2587-3474. eISSN 2587-3482. en_US
dc.identifier.uri https://doi.org/10.5281/zenodo.3949716
dc.identifier.uri http://repository.utm.md/handle/5014/10537
dc.description.abstract This article investigates the processes that take place during the forced thermo-oxidation of sunflower oil. The results obtained in the study showed a major impact of thermo-oxidation. (90 ± 2 °C. supplied air with a speed of 8 ÷ 10 L•h-1 for 50 hours), on the physico-chemical indicators of the studied oil. The acidity index of fresh sunflower oil increased 13.7 times, with a value of 2.46 mg KOH•g-1 of fat for the thermo-oxidized oil compared to the initial value of 0.180 mg KOH•g-1 of fat. The thermo-oxidation of sunflower oil caused a significant decrease of the saponification index, which indicates a significant degree of polymerization and leads to viscosity increase of the studied sunflower oil. In order to highlight the impact of heat treatments, the analysis was performed by IR spectroscopy and the possible mechanisms of unsaturated fatty acids forced oxidation under the influence of thermal factor were analyzed. It was established that the applied treatment favoured both the formation of carbonyl secondary compounds and the simultaneous formation of hydroperoxides and triglycerides containing hydroxylated groups. The accumulation of hydroperoxides and triacylglycerides that have hydroxyl functions have facilitated the course of polymerization reactions, which are to increase the viscosity of thermo-oxidized studied sunflower oil. The formation during thermo-oxidation of the trans-isomers of poly-unsaturated acids led to the appearance of the =CH group deformation vibration band at 966 cm-1 in the spectrum of thermo-oxidized oil, simultaneous to a slight reduction in the intensity of the =CH group deformation vibration band at 1098 cm-1 at the respective cis-isomer of polyunsaturated acids. en_US
dc.description.abstract În acest articol au fost cercetate procesele care au loc în timpul termooxidării forțate a uleiului de floarea-soarelui. Rezultatele obținute în cadrul studiului au arătat un impact marcant al termooxidării (90 ± 2 °C, barbotare aer cu o viteză de 8-10 litri /oră timp de 50 ore) asupra indicatorilor fizico-chimici ai uleiului. Indicele de aciditate a uleiului proaspăt de floarea soarelui a crescut de 13,7 ori, cu o valoare de 2,46 mg KOH /g pentru uleiul termo-oxidat față de valoarea inițială de 0,180 mg KOH /g. Termooxidarea uleiului de floarea soarelui a determinat o scădere importantă a indicelui de saponificare, ceea ce indică un grad important de polimerizare și conduce la creșterea vâscozității uleiului. Pentru a evidenția impactul tratamentelor termice a fost efectuată analiza prin spectroscopie IR și au fost analizate mecanismele posibile de oxidare forțată a acizilor grași nesaturați sub influența factorilor termici. S-a stabilit, că tratamentul aplicat a favorizat atât formarea compușilor secundari carbonilici, dar și formarea simultană a hidroperoxizilor și trigliceridelor care conțin grupări hidroxilate. Acumularea hidroperoxizilor și a triacilgliceridelor care au funcții hidroxilice au facilitat cursul reacțiilor de polimerizare, care se află la originea creșterii viscozității uleiului de floarea-soarelui termooxidat. Formarea în timpul termo-oxidării a trans-izomerilor acizilor polinesaturați a condus la apariția unei benzi de vibrație de deformare a grupului =CH la 966 cm-1 în spectrul uleiului termo-oxidat, concomitent cu o ușoară reducere a intensității benzii vibrației de deformare a grupului =CH la 1098 cm-1 din izomerul cis respectiv.
dc.language.iso en en_US
dc.publisher Tehnica UTM en_US
dc.rights Attribution-NonCommercial-NoDerivs 3.0 United States *
dc.rights.uri http://creativecommons.org/licenses/by-nc-nd/3.0/us/ *
dc.subject sunflower oil en_US
dc.subject thermal oxidation en_US
dc.subject spectroscopy en_US
dc.subject epoxides en_US
dc.subject fatty acids en_US
dc.subject acids en_US
dc.subject ulei de floarea-soarelui en_US
dc.subject termooxidare en_US
dc.subject epoxizi en_US
dc.subject acizi grași en_US
dc.title Mechanisms of sunflower oil transforming into forced thermal oxidation processes en_US
dc.type Article en_US


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