Effects of various oils on volatile compounds of deep-fried shallot flavouring

Shallot slices were heated with soybean, corn oils, lard or medium-chain triglycerides (MCT) at 150–160°C for 5 min and the volatiles of deep-fried shallot flavourings were studied. MCT-shallot flavouring, with 17 compounds, was evidently different from other shallot flavourings, with 28 compounds. Total amounts of volatiles were in the order of 70.2, 56.8, 43.6 and 23.3 mg kg−1 for lard-, corn oil-, MCT- and soybean oil-shallot flavourings, respectively. Sulphur- and nitrogen-containing compounds, which were the characteristic flavours of deep-fried shallot flavourings, were remarkably high in MCT-shallot flavouring. Lard-shallot flavouring contained, predominantly, oxygen-containing compounds. Soybean oil- and corn oil-shallot flavourings were similar in their profiles but varied in total amounts. MCT-shallot flavouring had a much lighter aroma due to lower amounts of oxygen-containing compounds, and a much less rancid note. Therefore, the use of MCT as a frying oil can providing a shallot flavouring product with better acceptability.