Effect of cooking on olive oil quality attributes

Virgin olive oil consumption, as final seasoning or within cooked foods, is increasing worldwide, mainly due to its recognized nutritional benefits. However, the maintenance of its quality and health attributes after thermal processing is frequently questioned. The aim of this article was to provide a careful review of published studies on the assessment of olive oil thermal processing, in order to ascertain the optimal settings for maximization of olive oil quality, while delaying the onset of oxidation products with detrimental health impacts. Through the selection of a particular olive grade, such as extra-virgin, virgin or refined olive oil, distinct starting compositions may be achieved, particularly regarding bioactive and antioxidant compounds, with a direct effect on thermal performance and nutritional value of cooked foods. Furthermore, different cooking practices, from common frying to boiling and including microwave cooking, along with operating conditions, as time, temperature and food amounts, undoubtedly modify the olive oil chemical profile. According to the compiled studies, in order to preserve virgin olive oil bioactive components heating time should be reduced to the minimum. Nevertheless, olive oil performance under prolonged thermal processing is usually equal or superior to other refined vegetable oils, due to its balanced composition regarding both major and minor components. However, as most of its bioactive components, including phenolic compounds, are gradually loss, it is economically advantageous to use lower olive oil grades and frequent replenishment under prolonged thermal processing. Future studies dealing with thermal degradation paths of minor olive oil components and their implication in human health will be of particular value to further clarify this issue. (C) 2013 Elsevier Ltd. All rights reserved.