Deep-frying is one of the most popular food cooking techniques. This processing operation causes a series of physico-chemical modifications in both oil and food, which are strongly related to food properties and the technological conditions used. The evaluation of the quality of the frying oils is, therefore, a key approach to identify the most suitable strategies to delay their deterioration. The aim of this work was to monitor the oxidative and hydrolytic stability of two oils (palm olein and extravirgin olive oil) and a blend of vegetable oils (high-oleic sunflower oil:palm olein, 60:40, v/v). A 3-step frying was carried out every day, under standardized frying conditions, for 5 consecutive days; 330 g french fries were fried per frying step. The oxidative stability of the frying oils was evaluated by means of the oxidative stability index (OSI) and peroxide value (PV), whereas the hydrolytic status was monitored by the free acidity value and the total diacylglycerol content (DAG). The smoke point and the total polar molecules (TPC) level were also determined. In general, the OSI value decreased during the frying process in the three oils, whereas PV showed the classical sinusoidal behavior as a consequence of their different formation and degradation into secondary oxidation products. Regarding the hydrolytic stability, the free acidity rose during frying (≤ 0.3% oleic acid) in all three oils, whereas the total DAG content remained almost constant for all frying processes. However, palm olein showed the highest percentage of total DAG (≤ 11%) as compared to the oil blend (≤ 5%) and the extra virgin olive oil (≤ 3%), which can be attributed to the palm olein extraction technology. Regarding the smoke point, the extra virgin olive oil showed the highest value (≤ 251°C), which is related to its fatty acid composition (in particular to its high oleic acid content). In the case of TPC (measured by Testo 265), palm olein showed the highest percentage (27%) in the last day of the frying experiment, thus exceeding the fixed limit for TPC in frying oils (25%).
D. Natale, M.T. Rodriguez-Estrada, G. Lercker (2011). Chemical performance of vegetable oils in repeated deep frying process. FRANKFURT : Euro Fed Lipid.
Chemical performance of vegetable oils in repeated deep frying process
NATALE, DANIELA;RODRIGUEZ ESTRADA, MARIA TERESA;LERCKER, GIOVANNI
2011
Abstract
Deep-frying is one of the most popular food cooking techniques. This processing operation causes a series of physico-chemical modifications in both oil and food, which are strongly related to food properties and the technological conditions used. The evaluation of the quality of the frying oils is, therefore, a key approach to identify the most suitable strategies to delay their deterioration. The aim of this work was to monitor the oxidative and hydrolytic stability of two oils (palm olein and extravirgin olive oil) and a blend of vegetable oils (high-oleic sunflower oil:palm olein, 60:40, v/v). A 3-step frying was carried out every day, under standardized frying conditions, for 5 consecutive days; 330 g french fries were fried per frying step. The oxidative stability of the frying oils was evaluated by means of the oxidative stability index (OSI) and peroxide value (PV), whereas the hydrolytic status was monitored by the free acidity value and the total diacylglycerol content (DAG). The smoke point and the total polar molecules (TPC) level were also determined. In general, the OSI value decreased during the frying process in the three oils, whereas PV showed the classical sinusoidal behavior as a consequence of their different formation and degradation into secondary oxidation products. Regarding the hydrolytic stability, the free acidity rose during frying (≤ 0.3% oleic acid) in all three oils, whereas the total DAG content remained almost constant for all frying processes. However, palm olein showed the highest percentage of total DAG (≤ 11%) as compared to the oil blend (≤ 5%) and the extra virgin olive oil (≤ 3%), which can be attributed to the palm olein extraction technology. Regarding the smoke point, the extra virgin olive oil showed the highest value (≤ 251°C), which is related to its fatty acid composition (in particular to its high oleic acid content). In the case of TPC (measured by Testo 265), palm olein showed the highest percentage (27%) in the last day of the frying experiment, thus exceeding the fixed limit for TPC in frying oils (25%).I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
