Tert-butylhydroquinone Research Articles

Developmental toxicity of synthetic phenolic antioxidants to the early life stage of zebrafish

Synthetic phenolic antioxidants (SPAs) have gained high concerns due to their extensive usages and unintended environmental release via various routes. Their contamination in water system could pose potential threat to aquatic organisms, therefore, the studies on the aquatic toxicology of this kind of chemicals are of high importance. In this research, the developmental toxicities of four commonly used SPAs, including butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), tert-butyl hydroquinone (TBHQ), and 2,2′-methylenebis (6-tert-butyl-4-methylphenol) (AO2246) were investigated using the zebrafish embryo toxicity test (ZFET). The results showed that these four SPAs exerted different acute toxicities to zebrafish, and the toxic order, based on their 96 h LC50 values, was AO2246 > TBHQ > BHA > BHT, and decreased hatching rates were induced for the embryos in BHA, TBHQ and AO2246 exposure groups. Non-lethal exposures of BHA (≤20 μM), TBHQ (≤20 μM), BHT (≤200 μM) and AO2246 (≤2 μM) decreased the heart rates and body lengths of zebrafish in exposure concentration-dependent manners. Diverse morphological deformities, including uninflated swim bladder, pericardial edema, spinal curvature, severe yolk deformation, or abnormal pigmentation, were induced in zebrafish larvae upon SPA treatments. The transcriptional levels of the related genes, examined by quantitative PCR, indicated that the interferences of SPAs with hypothalamic-pituitary-thyroid axis (HPT axis), GH/PRL synthesis and Hedgehog (hh) pathway contributed to their developmental toxicities in zebrafish. The up-regulation of pluripotency biomarker, Oct4, caused the developmental retardation during the early stages of zebrafish embryos in BHA and TBHQ exposure groups. The results obtained herein provided important information on the developmental toxicity of SPAs, which could be very helpful in guiding the risk assessment on their aquatic toxicology.

Identification and assessment of residual levels of the main oxidation product of tert-butylhydroquinone in frying oils after heating and its cytotoxicity to RAW 264.7 cells

tert-Butylhydroquinone (TBHQ) losses and the residual levels of 2-tert-butyl-1,4-benzoquinone (TBBQ) in tripalmitin at different heating temperatures with or without reflux over various time intervals were investigated. Heating at 120 °C resulted in the slowest TBHQ loss and the highest TBBQ levels (52.61–62.93 μg/mL). The highest TBBQ concentrations (111.73–164.67 μg/mL) at 5 and 8 h and residual concentrations of 10.23–46.95 μg/mL during heating at 170 °C over 24 h were observed. Furthermore, the potential cytotoxicity of TBBQ to RAW 264.7 cells was evaluated with the MTT assay, Hoechst 33258 staining test, and flow cytometry analysis. Results indicate that TBBQ dose- and time-dependently decreased the growth of cells and inhibited DNA synthesis by regulating the S/G2 transition. The TBBQ concentration giving 50% inhibition in RAW 264.7 cells was 10.71 μg/mL. This threshold value is lower than the residual level of TBBQ in oil, indicating the necessity for concerns over the safety of fried food in terms of TBBQ residues.

Propyl gallate (PG) and tert-butylhydroquinone (TBHQ) may alter the potential anti-cancer behavior of probiotics

The effects of antioxidant food additives on the anti-proliferative properties of probiotic bacteria and their subsequent effects on the growth of cancer cells were studied. Propyl gallate (PG) and tert-butylhydroquinone (TBHQ) were selected as the antioxidant, and Lactobacillus rhamnosus was used as the probiotic model. L. rhamnosus bacteria were exposed to PG and TBHQ and their resistance was assessed. Afterwards, the cell-free supernatants (CFS) of untreated bacteria (CFSU), PG treated bacteria (CFSP) and TBHQ treated bacteria (CFST) were isolated. The human colorectal adenocarcinoma cell line HT-29 was then exposed to isolated CFS and subjected to geno- and cytotoxicity assays and annexin V-fluorescein isothiocyanate (FITC) apoptosis/necrosis detection evaluation. The 3-(4,5-dimethylthiazol-2-Yl)-2,5-diphenyltetrazolium bromide (MTT) assay showed that CFSP and CFST were able to inhibit HT-29 growth with IC50 values of 70 and 120 μg/mL at 24 h, respectively, whereas CFSU showed no significant toxicity. DNA fragmentation was observed in the CFSP and CFST treated HT-29 cells, shown using 4′,6-diamidino-2-phenylindole dihydrochloride (DAPI) staining. An annexin V flow cytometry assay showed that the cells treated with CFSP and CFST resulted in 35% and 32% apoptosis, respectively. The qPCR results showed that the expression of pro-apoptotic caspase 9 gene was significantly increased in CFSP and CFST treated HT-29 cells compared with CFSU treated cells (P ≤ 0.05), whereas the expression of the pro-survival Bcl-xL gene was downregulated in the CFSP and CFST treated cells compared with CFSU treated cells (P ≤ 0.05). In conclusion, different food additives may affect the metabolomics of probiotics, which could subsequently influence human health.

Improving the Frying Performance and Oxidative Stability of Refined Soybean Oil by Tocotrienol‐Rich Unsaponifiable Matters of Kolkhoung (Pistacia khinjuk) Hull Oil

AbstractIncreasing consumer awareness for all natural products has quickly led to growing research on new resources of potent and profitable natural antioxidants. In this context, for the first time, the Kolkhoung hull oil (KHO) (Pistacia khinjuk)‐unsaponifiable matters (USM) (UHO) (100, 200, and 400 mg kg−1) were incorporated into refined soybean oil (RSO) and the oxidative stability of prepared oils was measured during 32 hours of frying. Then, the obtained results (oxidative stability) were compared to the samples containing tert‐butyl hydroquinone (TBHQ) (100 mg kg−1) as a common synthetic antioxidant. According to the results of oxidative stability assays of acid values, conjugated diene values and carbonyl values, and total polar compounds, the incorporation of UHO, particularly at a concentration of 200 mg kg−1, was more efficient in improving the oxidative stability compared to TBHQ. The tocol content of KHO (2043.4 mg kg−1) was higher than the reported amounts of other conventional edible oils. Furthermore, by incorporation of UHO into RSO, as compared with TBHQ, a better protection of naturally occurring antioxidants (tocopherols and sterols) was found after adding UHO to RSO. This fact was mainly attributed to the UHO's tocotrienol fraction. Hence, the USM of KHO can be used as a potent antioxidant to improve the oxidative stability of frying oils.

Influence of the Composition of Coconut-Based Emulsions on the Stability of the Colloidal System

The object of this research was to determine the influence of the composition of coconut milk-based emulsions on its physical and chemical stability. Coconut represents a highly important product globally and its competitiveness is restricted to its commercialization in the form of cakes, flour and coconut oil mainly to the European Community. The search for new alternatives to diversification of products as raw materials for food, pharmaceutical and cosmetic sectors represents a potential challenge. Coconut Pulp (CP) was milled with its Coconut Water (CW), separating the Coconut Fiber (CF), which was then dried at 40ºC and milled for its use in emulsions and homogenized at 10.000 rpm during 10 min. The surface response methodology was used with a composite central design (21 experiments), considering the independent variables: (CW+H₂O)/CP (1.5-2.5); xanthan gum (G_Xanthan): 0.25-0.75%, CF: 2.5-7.5%; tert-butyl hydroquinone (TBHQ): 100-200 mg/kg. In addition, dairy serum was used as surfactant and salt. The multiple regression method was used to predict the linear and quadratic terms and the interaction of the independent variables in the models. The optimal conditions were: (CW+H₂O)/CP: 2.0; G_Xanthan: 0.5%, CF: 5.0%; TBHQ: 200 mg/kg, reaching potential -ζ: -45.578±2.478 mV, index of stability through spectral absorption (R): 0.851±0.025; viscosity (μ): 741.7±25.5cP, color (L*:67.5±0.7, a*: 3.2±0.2, b*:8.6±0.5), Peroxide index (PI): 0.142±0.038 meqH₂O₂/kg, particle size (D₁₀:4.3±0.8 (μm, D₅₀:323.7±43.6 (μm and D₉₀:743.0±65.1 (μm) and Total Solids (TS): 19.981±0.303%. The results confer good physicochemical stability in the colloidal system studied, which could guarantee its effective use in the subsequent process, like in spray drying to obtain coconut powder.

Evaluation of attenuative effect of tert-butylhydroquinone against diazinon-induced oxidative stress on hematological indices in male Wistar rats.

Diazinon is an organophosphate toxicant that has been identified to induce oxidative stress within biological systems through altering biochemical and hematological indices, by generating free radicals while deteriorating the cellular antioxidant defense system. The present study was designed to evaluate the effectiveness of tert-butylhydroquinone (TBHQ), a synthetic food additive, in serving as an antioxidant against sub-lethal diazinon-induced oxidative stress in male Wistar rats. Animals were randomly divided into 4 groups: Control (treated with corn oil as a vehicle), diazinon (10 mg/kg/day), TBHQ (0.028 g/kg of diet) and a combination group of TBHQ (0.028 g/kg of diet) plus diazinon (10 mg/kg/day). All animals were treated orally once a day by gastric tube and treatments were continued for 7 weeks. Hematological indices, including red blood cell (RBC) indices and white blood cell (WBC) and platelet counts, were measured at the end of the treatment schedule. On comparison of the treatment groups with the untreated control group, RBC count, hemoglobin (Hb), hematocrit (Hct), mean corpuscular hemoglobin (MCH) and mean corpuscular hemoglobin concentration (MCHC) were significantly decreased in the diazinon and TBHQ+diazinon groups, while MCHC in the TBHQ group and MCV in the diazinon and TBHQ+diazinon groups were significantly increased. When the diazinon and TBHQ+diazinon groups were compared with the TBHQ group, RBC, Hb, Hct, and MCHC were significantly decreased whereas MCV was increased in both groups. Additionally, when comparing the TBHQ+diazinon group with the diazinon group, MCHC was determined to be significantly decreased. The results of the current experiments suggested that TBHQ could not efficiently protect blood cells against diazinon toxicity.

The Effect of Black Cumin Seed (Nigella sativa l.) Extract to Alloxan Induces Pancreatic Tissue Catalase Enzyme Activity of Male Wistar Rats (Rattus norvegicus)

Alloxan causes the formation of reactive oxygen through the reduction process of alloxan (dialuric acid) in the β cells of pancreas. Free radicals cause damage and decrease catalase enzyme activity. Black cumin seeds extract which contain carotenoids, thymoquinone, carvacrol, 4-terpineol, t-anethole, and tert-butylhydroquinone (TBHQ) has antioxidant activity that is expected to inhibit reactive oxygen species (ROS) that is expected to increase pancreatic catalase activity. This study used 24 male Wistar rats, divided into 3 groups:1)group of rats fed with standard food, 2)group of rats induced by alloxan 125mg/kg /BB intraperitoneally on day 1, 3)groups of rats induced by alloxan 125mg/kg/BB intraperitoneally on day 1 and were given by black cumin seed extract 2500mg/kg/BB orally on day 4 until 17. On the 18th day of all rats were sacrificed and pancreatic tissue catalase activity were measured by the spectrophotometric method. The results of One-Way ANOVA showed significant difference (p=0.003) pancreatic tissue catalase activity of groups of rats fed with standard food (1696,96U/g±414,10U/g) compared with group of rats induced by alloxan (1287,58U/g±88,45U/g). There was significant difference (p=0.001) of pancreatic tissue catalase activity of groups of rats induced by alloxan (1287,58U/g±88,45U/g) with a group of rats induced by alloxan and given with black cumin seed extract (1764,83U/g±199,69U/g). The conclusion of this study showed that the administration of alloxan significantly decreased pancreatic tissue catalase activity of rat and black cumin seed extract significantly increased catalase activity because cumin extract has antioxidant effects.

Tert-butylhydroquinone post-treatment attenuates neonatal hypoxic-ischemic brain damage in rats

Hypoxic-ischemic (HI) encephalopathy is a leading cause of dire mortality and morbidity in neonates. Unfortunately, no effective therapies have been developed as of yet. Oxidative stress plays a critical role in pathogenesis and progression of neonatal HI. Previously, as a Nrf2 activator, tert-butylhydroquinone (TBHQ) has been demonstrated to exert neuroprotection on brain trauma and ischemic stroke models, as well as oxidative stress-induced cytotoxicity in neurons. It is, however, still unknown whether TBHQ administration can protect against oxidative stress in neonatal HI brain injury. This study was undertaken to determine the neuroprotective effects and mechanisms of TBHQ post-treatment on neonatal HI brain damage. Using a neonatal HI rat model, we demonstrated that TBHQ markedly abated oxidative stress compared to the HI group, as evidenced by decreased oxidative stress indexes, enhanced Nrf2 nuclear accumulation and DNA binding activity, and up-regulated expression of Nrf2 downstream antioxidative genes. Administration of TBHQ likewise significantly suppressed reactive gliosis and release of inflammatory cytokines, and inhibited apoptosis and neuronal degeneration in the neonatal rat cerebral cortex. In addition, infarct size and neuronal damage were attenuated distinctly. These beneficial effects were accompanied by improved neurological reflex and motor coordination as well as amelioration of spatial learning and memory deficits. Overall, our results provide the first documentation of the beneficial effects of TBHQ in neonatal HI model, in part conferred by activation of Nrf2 mediated antioxidative signaling pathways.

Ultrasonic-Assisted Liquid-Liquid Microextraction Based on Natural Deep Eutectic Solvent for the HPLC-UV Determination of Tert-Butylhydroquinone from Soybean Oils

A novel natural deep eutectic solvent (NADES) composed of choline chloride (ChCl) and sesamol was prepared for the first time and was successfully employed in ultrasonic-assisted liquid-liquid microextraction (UALLME) of tert-butylhydroquinone (TBHQ) from soybean oils in the present study. In a typical experiment, 400 μL NADES as extraction solvent was added to a sample containing 0.2 g soybean oil, and then ultrasonic-assisted extraction was applied. After centrifugation, NADES phase containing TBHQ was directly analyzed by reverse phase high-performance liquid chromatography-ultraviolet detector (HPLC-UV), and no phase inversion was involved, which can satisfy the rapid sample pretreatment process. Under optimized condition, TBHQ showed a linear calibration curve in the range of 5~500 mg/kg (r2 = 0.9999) and lower limit of detection (LOD) of 0.02 μg/mL. The recoveries were in the range of 93.4~108.8%, and the intra-day and inter-day precision were less than 2.3%. This method was successfully applied to the determination of TBHQ in ten soybean oil samples, in which the results were close to that for conventional liquid-liquid extraction with methanol as solvent. Moreover, this sesamol-based NADES exhibited good protection ability to TBHQ during the extraction process due to the original antioxidant activity of sesamol.

Influence of Al2O3 nanoparticles structure immobilized upon glassy-carbon electrode on the electrocatalytic oxidation of phenolic compounds

Electrocatalytic oxidation of catechol (CT), dopamine (DP) and tert-butylhydroquinone (TBHQ) is demonstrated on glassy-carbon electrode (GCE) surfaces modified with alumina nanoparticles of different structures and morphologies. Higher electrochemical activity for the oxidation of CT, DP and TBHQ (peak-to-peak separation reduced from 500 to 50 mV in average) was verified on a GCE polished with α-Al2O3 suspension in comparison with the surfaces modified with θ and γ-Al2O3. This result seems to be correlated with the alumina structure instead of the surface area, as the α-Al2O3 presented 10-fold lower surface area than θ and γ-Al2O3, or particle size. Gold and platinum surfaces were similarly modified with α-Al2O3 suspension and the distinguished electrochemistry of the phenolic compounds was not observed on the platinum-modified surfaces, which may indicate effect of the substrate on the immobilization of alumina. High stability of the GCE surface modified with α-Al2O3 was attested by continuous amperometric detection of the phenolic compounds under hydrodynamic conditions, and superior analytical sensitivity of the α-Al2O3-modified electrode was observed with comparable results to those obtained on GCE modified with multi-walled carbon nanotubes. These results demonstrate that α-Al2O3 particles commercially available for electrode polishing can be used to develop highly sensitive, reproducible and stable electrochemical sensors, but also indicate that electrode polishing may generate improved electrochemical responses attributed to “cleaned surfaces”.

Effect of Polar and Non‐Polar Compounds from Oxidized Oils on Oxidative Stability in Corn Oil

The effects of polar and non‐polar compounds recovered from oxidized corn oils on oxidative stability in bulk oils are evaluated in the presence or absence of an antioxidant, tert‐butylhydroquinone (TBHQ). The balance of antioxidant and prooxidant compounds in oils is confirmed using the 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) spectroscopic method. Polar compounds accelerated the depletion of headspace oxygen content and increased the conjugated dienoic acid value and p‐anisidine value in oils with or without 200 ppm TBHQ, which implies that polar compounds from oxidized lipids are prooxidants. However, added non‐polar compounds showed no prooxidative properties in oils, irrespective of the presence of TBHQ. The antioxidant‐prooxidant balance (APB) value, which is calculated as the ratio of the loss of DPPH in isooctane to that in methanol, may reflect the content balance between antioxidant and prooxidative oxidized lipid products in oils. Low APB values indicate that oils are in a highly oxidized state.Practical Applications: Polar compounds from oxidized oils act as prooxidants. Therefore, it is necessary to determine the polar content in frying oils accurately. Using modified DPPH methods, not only the content of antioxidants but also prooxidative polar compounds in oils can be determined simultaneously. Modified DPPH methods can predict the oxidative stability of frying oil and help to extend the shelf‐life of fried foods in the food industry.Polar compounds from oxidized oils function as prooxidants. Non‐polar compounds do not act as prooxidants nor antioxidants. Modified 2,2‐diphenyl‐1‐picrylhydrazyl methods can predict the oxidative stability of frying oil.

The Effect of Surfactant Addition towards Dispersion and Antioxidant Activity of tert-butylhydroquinone in Biodiesel

Biodiesel is a renewable fuel as an alternative to fossil fuel. Currently, biodiesel is commercially used as a mixture of solar diesel. Biodiesel has many advantages. However, it has an instability issue towards oxidation which could lead to the low shelf life and quality degradation. Antioxidant additives such as tert-butylhydroquinone (TBHQ) is commonly used to prevent the oxidation. However, as an antioxidant additive, TBHQ has a low dispersion in biodiesel, thus it limits its antioxidant activity. Therefore, TBHQ is incorporated into biodiesel which was previously mixed with surfactant in order to increase its dispersion to increase its performance. In this research, three types of surfactants were used namely Sorbitan Monooleate, Glycerol Monostearate, and Polyglyceryl-4-isostearate to increase the solubility of TBHQ and its antioxidant activity. The functional group changes due to oxidation reaction product was confirmed by using FTIR. The solubility of the biodiesel mixtures was tested using UV-Vis Spectrophotometer. Result shows that the mixture of 100 ppm Polyglyceryl-4-isostearate with 2000 ppm TBHQ performed the most stable dispersion in biodiesel over one week observation followed by Glycerol Monostearate and Sorbitan Monooleate. The biodiesel quality in respect to acid number and iodine value were analyzed to evaluate the antioxidant performance of the additive-surfactant mixtures. The best improvement of oxidative stability of biodiesel over four-week storage time was performed by addition of 100 ppm Polyglyceryl-4-isostearate compared with other surfactants. These findings provide a potential use of surfactant, especially Polyglyceryl-4-isostearate, as a solubility enhancer as well as, more importantly, helping the antioxidant activity of phenolic additives in biodiesel .

Electro-Catalytic Resolution and Simultaneous Determination of Two Phenolic Antioxidants

An ultrasensitive voltammetric sensor for the resolution of tert-butyl hydroquinone (TBHQ) and propyl gallate (PG) at submicromolar levels has been developed. Acetylene black modified gold electrode (AB/GE) has been recognized to be a simple yet highly sensitive sensing platform enabling the individual determination of these antioxidants within a wide range of concentration from 1.0 × 10−4 M to 3.0 × 10−7 M and 1.0 × 10−4 M to 7.0 × 10−8 M with detection limits 2.8 × 10−8 M and 4.3 × 10−8 M for TBHQ and PG respectively. Moreover, highly resolved peaks for the oxidation of TBHQ and PG with a separation of 206 mV have been observed on AB/GE which in turn facilitated their simultaneous determination. The potential of the developed sensor toward the quantification of TBHQ and PG in fats and oils has proved its efficacy as a promising tool for food quality control.

Fortification of refined soybean oil by hull oil of two Iranian wild pistachios: Improving thermal stability during frying process

ABSTRACTIn this research, various concentrations of Kolkhoung (Pistacia khinjuk) hull oil (KHO), Beneh (Pistacia atlantica) hull oil (BHO), and Sesame (Sesamum indicume L. cv. Dezful) seed oil (1%, 2%, 4%, and 6%) as natural antioxidants were added to refined soybean oil (RSO) and antioxidant effect of these compounds was compared with that of tert-butyl hydroquinone (TBHQ) during 32 h frying process at 180°C. For this purpose, variation of acid value (AV), conjugated diene value (CDV), carbonyl value (CV), total polar compounds, and total tocol (TT) and total sterol contents of RSO was monitored during frying process. Results of oxidative stability assays revealed that 4%KHO had the best antioxidant effect which was fairly equal to that of TBHQ, followed by 4%BHO. It should be mentioned that in contrast to TBHQ, KHO and BHO are not pure antioxidant. The remarkable antioxidant effect of KHO and BHO during thermal process was due to high tocotrienol content and presence of suitable amount of Δ-7-avenasterol and Δ-5-avenasterol, respectively [TT content of KHO (2041 mg/kg) much higher than that of ordinary edible oils and 92.7% of TT content in KHO is formed by tocotrienols]. Antioxidant activity of Δ-7-avenasterol and Δ-5-avenasterol and tocotrienols during frying process was attributed to formation of stabilized tertiary alkyl radicals. These radicals cut down radical chains formed during frying process.

Effect of natural antioxidants on inhibition of parent and oxygenated polycyclic aromatic hydrocarbons in Chinese fried bread youtiao

The effects of three natural antioxidants (rosemary extract, tea polyphenol, and antioxidant of bamboo) on the levels of 16 polycyclic aromatic hydrocarbons (PAHs) and five oxygenated PAHs (OPAHs) in typical Chinese fried food youtiao were investigated, with synthesized antioxidant tert-butylhydroquinone (TBHQ) added to the frying oil for comparison. Soybean and palm oils were chosen as frying oils. The antioxidants were added to the frying oil in concentrations of 60, 120, and 180 mg/kg, and PAH and OPAH analysis was performed using GC-MS. Furthermore, the acid value, peroxide value, and polar components were detected to evaluate the antioxidant effect. Compared to samples without added antioxidants, the addition of TBHQ, rosemary extract, tea polyphenol, and antioxidants of bamboo reduced the total PAH and total OPAH concentrations by up to 30.30%, 23.47%, 11.38%, and 28.85%, respectively, for youtiao fried in soybean oil, and by up to 38.94%, 27.56%, 9.45%, and 39.26%, respectively, for youtiao fried in palm oil. The best inhibition was achieved by antioxidant of bamboo, which also showed good performance in slowing youtiao quality degradation. These results could inform good frying practice to improve the quality of fried food with low PAH and OPAH levels, and aid understanding of the new potential benefits of natural antioxidant extracts.

Synthetic Phenolic Antioxidants Cause Perturbation in Steroidogenesis in Vitro and in Vivo.

Synthetic phenolic antioxidants (SPAs) are closely correlated with human life due to their extensive usages, and increasing concerns have been raised on their biosafety. The previous controversial findings caused continuous debates on their potential endocrine disrupting effects. In the present study, four commonly used SPAs, including butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), tert-butyl hydroquinone (TBHQ) and 2,2'-methylenebis(6-tert-butyl-4-methylphenol) (AO2246), were investigated for their estrogenic effects, and the results from in vitro screening assays showed SPAs themselves had negligible estrogen receptor binding affinities. Nevertheless, significant increase in E2 secretion was observed in H295R cells treated with SPAs, especially for BHA. The transcriptional levels of steroidogenic enzymes, including StAR, 3βHSD, CYP11B1, and CYP11B2 were up-regulated via the mediation of protein kinase A (PKA) signaling pathway. In vivo experiment confirmed that waterborne exposure to BHA disturbed E2 and testosterone (T) levels in zebrafish gonad, thus causing potential estrogenic effects through the regulation of hypothalamic-pituitary-gonadal-liver axis (HPGL-axis). Accordingly, this study has provided new insights for SPA-induced endocrine disrupting effects. Considering the allowable maximum level of individual BHA or in combination with TBHQ and BHT in foodstuffs (200 mg kg-1), the perturbation in steroidogenesis observed for relatively low concentrations of SPAs would need more public attention.

Algal biodiesel stabilization with lower concentration of 1:3 ratios of binary antioxidants – Key factors to achieve the best synergy for maximum stabilization

Poor storage stability of biodiesel is considered a major problem for its commercialization. The use of commercial antioxidants has been proven very effective for biodiesel stabilization; hence these are frequently being used for long term storage of biodiesel. Moreover, in comparison to individual antioxidants, use of their binary combinations with their optimized concentrations could be more economical and highly effective to improve the storage behavior of biodiesel. In present report the effectiveness of lower concentration of binary antioxidants on the oxidation stability of algal biodiesel was studied. The 500, 600 and 700 ppm concentrations of binary combinations of three antioxidants [i.e. Pyrogallol (PY); Propylgallate (PrG) and tert-butyl hydroquinone (TBHQ)], are prepared at weight ratios of 1:1, 1:2, 1:3 and 1:9 and vice-versa. Although, storage stability was increased with increase in antioxidant concentration; however, the best synergy was obtained with 1:3 ratios of binary antioxidants with 500 ppm concentration of binary antioxidants.

Antioxidative Properties and Interconversion of tert-Butylhydroquinone and tert-Butylquinone in Soybean Oils.

During the process of antioxidation of tert-butylhydroquinone (TBHQ) in oil and fat systems, tert-butylquinone (TQ) can be formed, which has higher toxicity than TBHQ. The changes of TBHQ and TQ in edible oils at room temperature (RT) or under thermal treatment were investigated. Under thermal treatment, volatilization was the main pathway of TBHQ loss in edible oils. TQ was the main oxidation product of TBHQ under thermal treatment as well as at RT. The amount of TQ in thermally treated oils was much less than that in oils stored at RT due to the decreased amount of oxygen dissolved in oils and easy volatilization of TQ at high temperature. In addition, TQ can be reduced to TBHQ by reduction components in edible oils, but the conversion amount was very small. Thus, TQ, theoretically having no antioxidative property, presented a very weak antioxidative activity equivalent to that of BHA due to the presence of insignificant amount of TBHQ formed from TQ in edible oils. The narrow potential difference of 0.059 between oxidation and reduction peaks of TBHQ and TQ resulted in easy interconversion of TBHQ and TQ under the action of common oxidation and reduction substances which have a higher oxidation potential or a lower reduction potential than they have.

Alternative binary blends and their synergistic effect on stability of soybean biodiesel

The primary antioxidant tert-butylhydroquinone (TBHQ) and an alternative additive, named 1,4-bis(ethylamino)-9,10-anthraquinone, were mixed to yield a potent blend able to be used in the field of biodiesel preservation. Physicochemical parameters such as peroxide value, total acid number, density and induction period were used to evaluate the effectiveness of the combination in stabilising soybean biodiesel during the accelerate storage period of degradation. The induction period values were also used to calculate the occurrence of synergistic effect, and it was observed a high percentage of synergism for the combined additives. The results showed that the presence of target alternative additive also enables lower the concentration of the primary antioxidant (TBHQ) in the blend. The cost-effective comparison was evaluated, and it was verified that the final cost of biodiesel can also be lowered, since the amount of additives (in the blend) required to meet the biodiesel specifications was reduced between 70 and 88%.

Antioxidant potency of gallic acid, methyl gallate and their combinations in sunflower oil triacylglycerols at high temperature

Lipid peroxidation and polar compounds formation in sunflower oil triacylglycerols at 120°C were investigated in the presence of gallic acid (GA), methyl gallate (MG), MG/GA combinations (75:25, 50:50, and 25:75), and tert-butylhydroquinone (TBHQ). Hydroperoxide-based kinetic parameters (IP, induction period, min; ki, rate constant during IP, meq/kgmin) of control sample (38.0; 2.0346) were considerably improved by TBHQ (201.1; 0.0267), followed by GA (163.8; 0.0837), MG (151.2; 0.0983), and the combinations (∼184.4; ∼0.0861) with an average synergy of 18.6%. Regarding the polar compounds inhibition, the best antioxidant performance (the ratio of IP to oxidized triacylglycerol monomers at IP, min/%; time reaching 10% of triacylglycerol dimers and polymers, min) in general belonged to MG/GA 75:25 (42.4; 263.0), GA (43.2; 249.9), MG (38.0; 237.5), and TBHQ (17.7; 214.4), respectively. The kinetic parameters based on the formation of polar compounds than hydroperoxides provided more reliable results to evaluate antioxidant potency at high temperature.