129 Journal of Oil Palm Research Vol. 33 (1) March 2021 p. 129-139 DOI: https://doi.org/10.21894/jopr.2020.0071 INTRODUCTION Fried food products are popular nowadays with good acceptance and demand globally. Deep frying is a cooking method whereby the food is immersed in hot oil or fat. Deep frying method used for the production of fried food products has been used for decades and the preferable method of cooking nowadays as it is simple, fast and convenient providing distinctively good sensory properties (i.e. texture, aroma and favour). The crispy outer crust with moist inner part enhances palatability of the food. Besides domestic cooking, deep frying method is being used commercially in restaurants (including fast food restaurants), mass catering and various food industries (including snack industry). Fast food restaurants have been experiencing exponential growth worldwide, especially in big cities due to changes in lifestyles when people have limited time to prepare daily meals (Shaharudin et al., 2011). The popularity of fast food restaurants among the younger generation is undeniable as they ofer menus with afordable prices, easy to access and convenient (Habib et al., 2011), complemented with good marketing and advertising strategies. Numerous types of lipids, in the form of liquid, solid and semi-solid at room temperature are available in the market for deep frying. These lipids act as a medium for heat transfer to the food. Despite being simple, fast and convenient, deep frying is a complex process and may result in physical and chemical changes when the lipids are being used repeatedly at a high temperature of between 150C-200C (thermal degradation) (Ahmad Tarmizi FRYING OIL QUALITY IN FAST FOOD RESTAURANTS IN EAST COAST OF MALAYSIA: A PRELIMINARY SURVEY NUR HAQIM ISMAIL*; AZMIL HAIZAM AHMAD TARMIZI*; NORAZURA AILA MOHD HASSIM*; SIVARUBY KANAGARATNAM* and NOOR LIDA HABI MAT DIAN* ABSTRACT Fresh, in-use regardless the days of frying and discarded oils were collected from fast food restaurants in Kuala Terengganu, Terengganu, Malaysia to investigate the quality of the frying oil used in the commercial frying industries. The fresh oils used in these restaurants were palm olein and/or palm oil. Oxidative stability index (OSI), smoke point, colour, free fatty acid (FFA), polar compound, peroxide value (PV) and ք-anisidine value (ք-AV) were evaluated. The fresh oils showed Tuality that is within specifcation of standards and references. The in-use oils showed a high degree of deterioration by having a lower OSI, smoke point, and darker colour. High levels of FFA showed that 42.9% of in-use oils and 100% of discarded oils had exceeded the maximum limit of 1%. Polar compound of 42.9% of the in-use oils and 50% of the discarded oils had exceeded the maximum limit (>27%). As high as 81% of the in-use oils and 75% of the discarded oil collected having ք-AV of more than 10 which suggests that inspection by the local authority should be carried out to monitor the quality of the cooking oil used in the fast food restaurants. Keywords: fast food restaurants, frying oil, oil quality. Received: 25 February 2020; Accepted: 9 July 2020; Published online: 22 September 2020. * Malaysian Palm Oil Board, 6 Persiaran Institusi, Bandar Baru Bangi, 43000 Kajang, Selangor, Malaysia. E-mail: nurhaqim.ismail@mpob.gov.my