Abstract
A novel caffeic acid derivative, butylated methyl caffeate (BMC), was synthesized via esterification between butylated caffeic acid (BCA) and methanol. Its antioxidant activity was investigated and compared to TBHQ, caffeic acid (CA), methyl caffeate (MC) and BCA through deep-frying, an oven test in oil-in-water emulsions and DPPH radical scavenging. BMC showed the strongest antioxidant activity among the five antioxidants in emulsions and its antioxidant activity was almost as strong as BCA in frying. Its soybean oil-water partition coefficient was 9.18 due to its ester and tert-butyl groups, far greater than those of MC (4.82), BCA (2.41), CA (0.84) and TBHQ (3.22). This meant that it was much more soluble in the lipid phase than the other four antioxidants in emulsions. The DPPH radical scavenging activity of BMC was near TBHQ, lower than the other three because of its steric hindrance and less functional phenolic hydroxyl groups compared to others when their masses were the same.
Highlights
Acid values (AV), Iodine values (IV) and Conjugated diene (CD) values were determined for samples using the International Union of Pure and Applied Chemistry (IUPAC) method (Paquot, 1979; Okubanjo et al, 2019)
The emulsions were held in an oven at 63 ± 1 °C for 35 days and the peroxide values (POV) were measured as the index according to the American Oil Chemists Society (AOCS) Official Method Cd 8–53 once a day (Firestone, 1998)
Rf values of butylated methyl caffeate (BMC) and butylated caffeic acid (BCA) obtained by thin-layer chromatography (TLC) were 0.67 and 0.01, respectively
Summary
Commercial soybean oil (acid value: 0.17g KOH/kg; iodine value: 124.7 g/100g) was purchased from the supermarket, Shanghai, China. CA, TBHQ, Tween 80, KH2PO4 and K2HPO4.7H2O were purchased from Sigma-Aldrich Trading Co. Ltd. Silica gel and other chemicals used in this experiment were all AR grade and came from Sinopharm Chemical Reagent Co. Ltd. All of the reactions were monitored by thin-layer chromatography (TLC) performed on silica gel GF254
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
