Chicken breast, a food rich in protein, was deep-fried in soybean oil (SBO) at 140, 175 and 190 °C for 20 continuous batches, and the profiles of acid value (AV), peroxide value (PV), 2-tert-Butyl-1,4-dihydrobenzoquinone (TBHQ), and 2-tert-Butyl-1,4-benzoquinone (TBBQ) in SBO and fried chicken breast were determined. The results suggested that frying at 140 °C produced increased conversion of TBHQ to TBBQ and oxidation of the frying oil than at 175 °C, which was close to that found at 190 °C. The highest TBBQ peak concentration of 2.89 ± 0.12 and 13.88 ± 0.27 mg/kg for fried chicken breast and frying oil corresponded to the 7th and 6th frying batch at 140 °C, respectively. The experimental results on determination of the AV, PV, moisture and the content of oxygen in frying oil suggested that more moisture and oxygen were retained in oil when frying at 140 °C than that at 175 °C, which may explain the over-conversion of TBHQ to TBBQ when frying at low temperature. The results on aeration frying and water injection frying experiments indicated that moisture and oxygen had a great impact on the oxidation of TBHQ in frying oil.
2- tert -Butyl-1,4-benzoquinone (TBBQ), the main oxidation product of tert -butyl-hydroquinone (TBHQ) during frying, is cytotoxic and its residual levels in frying oils and foods are unknown. In this study, TBBQ residues have been evaluated during the preparation of french fries. Results showed that frying at 140 °C resulted in the highest TBBQ peak concentration (48.42 mg kg −1 ) compared with frying at 190 or 170 °C. This unexpected finding can be attributed to more extensive hydrolytic reaction when frying at the lower temperature, generating more peroxyl radicals. TBBQ concentrations proved to be independent of the oil type among various unsaturated oils. However, higher TBBQ levels were observed in saturated palm oil and crude soybean oil than in unsaturated oil or refined oil. Continuous frying leads to the accumulation of a large amount of TBBQ in fried food. After frying 1–5 batches, TBBQ levels in both the frying oil and fries were above 10 mg kg −1 , exceeding its critical cytotoxic concentration (IC 50 value of 10.71 mg kg −1 for RAW 246.7 cells in our previous study), warranting concern with respect to the safety of fried food. FTIR has been utilized as an effective tool for visually monitoring the degree of oxidation in the frying medium with respect to its hydrogen peroxide level, which contributes to the increased level of TBBQ derived from TBHQ therein.
This study aimed to obtain a reliable evaluation about addition of tert -butylhydroquinone (TBHQ), and distribution of TBHQ and 2 -tert -butyl-1,4-benzoquinone (TBBQ) contents in typical edible oils and oleaginous foods marketed in Hangzhou City. Briefly, the probability of labeled with addition of TBHQ in foods decreased from 36.45 ± 2.6% to 28.78 ± 3.7% in the period from 2018 to 2020. In the 135 analyzed samples, TBHQ contents were far less than the maximum legal additive amount, and TBBQ contents ranged from below its limit of quantification (LOQ) to 13.54 ± 1.15 mg/kg. The conversion rate from TBHQ to TBBQ in edible oils was 2.94 ± 1.17%, much lower than that in other food categories. Further research determined that the process method and food composition were the main factors for different conversion rates from TBHQ to TBBQ in various food categories. In addition, oil consumption was found to be the primary source of dietary intake of TBHQ and TBBQ.
危险品化学品经营许可证（带存储）