Transformation of TBHQ in Lard and Soybean Oils During Room Temperature Storage

Abstract

Tert‐butylhydroquinone (TBHQ) has been widely used in oils and oleaginous foods as powerful antioxidants, and TBHQ can be easily converted to tert‐butylquinone (TQ) at room temperature. In this work, the changes in TBHQ and TQ contents in lard and soybean oil during storage are investigated in detail. Results show TBHQ content decreases gradually during storage as the TQ content increases in both lard and soybean oil at room temperature. Moreover, the decrement in TBHQ is much larger than the increment in TQ, and the difference increase over storage time. This suggests that TBHQ is transformed into other compounds in addition to TQ. To identify these compounds, lard containing 200 mg kg−1 of TBHQ stored for 150 days is extracted by methanol. Prep‐LC is used to purify the transformation products of TBHQ during storage. The products are identified as 2‐methylallyl‐hydroquinon and 2‐(2‐methoxy‐2‐methylpropyl)‐hydroquinone by LC/MS and NMR. The transformation mechanism of these products is also proposed. Practical Applications: TBHQ is very prone to transformation due to its strong antioxidant activity. However, the transformation products of TBHQ in fats and oils may have an adverse effect on the shelf‐life and safety of lipid rich products. Moreover, the accuracy of TBHQ quantitative detection is also affected. The contents change of TBHQ, TQ, and other transformation products in lard and soybean oil containing 200 mg kg−1 TBHQ are investigated at room temperature. Apart from TQ, other transformation products of TBHQ are purified and identified. This work enriches the research on the transformation mechanism and products of TBHQ in lipid systems at room temperature. It provides better understanding on the safety and detection accuracy of TBHQ as well. Lard and soybean oil containing 200 mg kg−1 tert‐butylhydroquinone (TBHQ) are stored for 150 days at room temperature. TBHQ and the transformation products of TBHQ are extracted by methanol and detected by NP‐HPLC. To identify the transformation products of TBHQ, Prep‐LC is used to isolate and purify the transformation products of TBHQ during storage. The products are identified as 2‐methylallyl‐hydroquinon and 2‐(2‐methoxy‐2‐methylpropyl)‐hydroquinone by LC‐MS and NMR. The transformation mechanism of these products is also proposed.

Polar compound composition of four vegetable oils as affected by tert‐butylhydroquinone (TBHQ) and chlorophyll during room‐temperature storage

“…However, the amount of OxTG in the experimental group first increased and then decreased as the PV increased. This finding may be due to the protection provided by TBHQ and chlorophyll to prevent the autoxidation of PO and suggests a hydrogen‐donating mechanism breaking the radical chain reactions (Lanfer‐Marquez et al ., 2005; Xu et al ., 2019a, Xu et al ., 2019b). Specifically, the antioxidant capacity of chlorophyll in the dark may be achieved in the following manner.…”

“…The measurement of TPC was performed gravimetrically following the AOCS official method Cd 20‐91 with minor modifications. In this research, a separation technology was used to separate the non‐polar and polar fractions by employing the edible oil polar compounds (EOPC) fast‐separation chromatographic system (Cao et al ., 2013; Xu et al ., 2019a; Xu et al ., 2019b).…”

“…TPCs can be further classified into TAG oligomers (TGOs) and TAG dimers (TGDs), which represent the degree of polymerisation reaction of edible oils; oxidised TAG monomers (OxTGs) act as indicators of the beginning of oxidation, whereas DGs, monoglyceride (MGs) and free fatty acid (FFAs) illustrate the hydrolytic alteration that occurs during the oxidation process (Xu et al ., 2019a, Xu et al ., 2019b). These compounds differ not only in polarity and molecular mass but also in adverse health effects.…”

Hexaarylbiimidazole-based polyurethane positive photoresists for UV lithography

“…The two hydroxyl groups on the benzene ring of TBHQ possess high activity, can react with free radicals generated more stable substance. The antioxidant capacity of TBHQ is greater than propyl gallate (PG), butylated hydroxytoluene (BHT), butylated hydroxyanisole (BHA), [30][31][32] so it often serves as a kind of excellent antioxidants in food package. The interaction mechanism between TBHQ and radicals remains to be disclosed.…”

“…The popular mechanism tends to think that the hydrogen atoms from phenolic hydroxyl groups will combine with radicals to form a more stable substance while TBHQ will become less active quinones. 31 In order to investigate whether TPIR reacted with TBHQ to generate TPI, the mixture of TBHQ and 2-Cl-HABI without a polymerizable hydroxyl group was prepared and irradiated for 10 min under UV light, followed by the column chromatography for product separation(Figure S1). The products were characterized by mass spectrometry (MS) and nuclear magnetic resonance (NMR).…”