Systematic comparison on the deep-frying performance of different vegetable oils from literature data using the rate of parameter change approach

Abstract

Direct comparison of the frying performance of vegetable oils based on the data reported in literature is difficult because of the inconsistent experimental protocols used in different studies. This research aimed to develop a method, known as ‘Rate of Parameter Change’ (RPC) to evaluate the deep-frying results obtained from literature data. A literature search was conducted using PubMed, Web of Science and Scopus to identify the studies that reported the deep-frying results using different types of vegetable oils (palm olein, canola oil, soybean oil, sunflower oil). A total number of 32 studies were selected in this work based on the pre-defined selection criteria. The quality parameters examined were polyunsaturated fatty acid composition (PUFA), free fatty acid content (FFA), total polar compound content (TPC), anisidine value (AV) and di- and polymerized triacylglycerol content (DPTG). The data extracted from each study were normalized with the number of frying cycles reported in the study. The normalized values for a parameter examined were reported as RPC. The RPC computed from different studies were then compared and evaluated using a box plot. This method had revealed a distinct trend, where the PO was found to have a higher stability against thermo-oxidative alterations compared to the soft oils (CNL, SBO, SFO) during deep-frying application. However, some of the calculated RPC values have large standard deviations which are attributed to the inconsistent experimental protocols used in different studies. This observation calls for a standardized protocol in deep-frying experiments to facilitate the comparison of quality parameters between different studies and between different types of vegetable oils.