Action and fate of natural and synthetic antioxidants during frying

Occurrence of synthetic phenolic antioxidants in foodstuffs from ten provinces in China and its implications for human dietary exposure

Synthetic phenolic antioxidants (SPAs) are widely used as food additives to delay the oxidation rate of oils and oil products. The concentrations and compositions of SPAs in Chinese residents' most popular daily foods and the resulting exposure risk of SPAs are not clear. Therefore, this study collected food samples in 13 food categories (n = 289) from 10 provinces in China. At least one of the SPAs was detected in approximately 99.7% of foodstuffs, and the concentration of ∑SPAs ranged from not detected to 7830 (geometric mean (GM): 296 ng/g wet weight). 2,6-2 tert butyl p-1,4-benzoquinone (BHT-Q) was the main transformation product, but SPAs in food tend to exist in the parent form. A significant difference between food categories was analyzed. The highest GM of ΣSPAs occurred in cereals and cereal products, which was approximately 8 times higher than that in beverages. The estimated daily intakes of ΣSPAs in Chinese preschoolers, school-age children, adults and elderly individuals were 22200, 9970, 7540 and 7700 ng/kg bw/day, respectively. The exposure risks of SPAs decreased with age. This is the first simultaneous analysis of SPAs in multiple provinces and multiple categories of foodstuffs.

Therapeutic Properties and Use of Extra Virgin Olive Oil in Clinical Nutrition: A Narrative Review and Literature Update

Extra virgin olive oil (EVOO) is a cornerstone of the Mediterranean diet (MedD). In this narrative review, we synthesize and illustrate the various characteristics and clinical applications of EVOO and its components—such as oleic acid, hydroxytyrosol, and oleuropein—in the field of clinical nutrition and dietetics. The evidence is split into diet therapy, oleic acid-based enteral nutrition formulations and oral supplementation formulations, oleic acid-based parenteral nutrition, and nutraceutical supplementation of minor components of EVOO. EVOO has diverse beneficial health properties, and current evidence supports the use of whole EVOO in diet therapy and the supplementation of its minor components to improve cardiovascular health, lipoprotein metabolism, and diabetes mellitus in clinical nutrition. Nevertheless, more intervention studies in humans are needed to chisel specific recommendations for its therapeutic use through different formulations in other specific diseases and clinical populations.

Schemes for enhanced antioxidant stability in frying meat: a review of frying process using single oil and blended oils

Deep-fried meat products are widely popular. However, harmful compounds produced by various chemical reactions during frying have been shown to be detrimental to human health. It is of great necessity to raise practical suggestions for improving the oxidation problem of frying oils and frying conditions in some aspects. Vegetable oils are not as thermally stable as saturated fats, and blended oils have higher thermal stability than single oil. In this review, we discussed the oxidation problems frying oils and meats are subject to during frying, starting from the oil oxidation mechanism, the effects of different oils and fats on the quality of different fried meats under different conditions were concluded to alleviate the oxidation problem, to highlight the necessity of applying blended oils for frying, and effective antioxidants added to frying oils are also introduced, that would provide more convenient and practical options for obtaining higher quality of fried meat products and offer better understanding of the potential of blended frying oils for frying meat products.

Stability of Bioactive Compounds in Olive-Pomace Oil at Frying Temperature and Incorporation into Fried Foods

The stability of minor bioactive compounds in olive-pomace oils (OPOs) was evaluated at frying temperature under the conditions of a thermoxidation test. Bioactive compounds analyzed included squalene, tocopherols, sterols, triterpenic acids and alcohols, and aliphatic alcohols. In order to determine the amount of OPO bioactive compounds incorporated into foods after frying, three different kinds of frozen products were selected, i.e., pre-fried potatoes (French fries), pre-fried battered chicken nuggets, and chicken croquettes (breaded patties), and were used in discontinuous frying experiments. Results obtained in both the thermoxidation and frying studies showed high stability of triterpenic alcohols (erythrodiol and uvaol), oleanolic acid, and aliphatic alcohols, naturally present in OPOs. In all fried foods, the content of lipids increased after frying, as expected, although the extent of absorption of OPOs into fried foods and the exchange with food lipids depended on the food characteristics. Overall, frying with OPOs improved the nutritional properties of all products tested by increasing the level of oleic acid and by the incorporation of squalene, triterpenic acids and alcohols, and aliphatic alcohols, in significant quantities.

Oxidative Stability and Antioxidant Activity in Canned Eels: Effect of Processing and Filling Medium

The effect of canning and the use of different filling media (sunflower oil, olive oil, and spiced olive oil) on oxidation parameters (acidity, peroxide value (PV), and thiobarbituric acid reactive substances (TBARS) index), antioxidant capacity, and total phenol and vitamin E contents in eels was studied. A preliminary frying treatment caused a decrease in titratable acidity and an increase in TBARS, antioxidant capacity, and vitamin E in the eel muscle. During sterilization, TBARS also increased significantly. The magnitude of the changes depended on the filling medium. Storage also had a significant effect on oxidation parameters in eel muscle and in filling media. After one year of storage, the sunflower oil and canned eels packed in this oil presented higher antioxidant capacity and vitamin E content than olive oil, spiced olive oil, or canned eels packed in these oils. However, the total phenol contents were higher when olive oil or spiced olive oil were used as filling media. Despite the losses, the results show that the canning process and subsequent storage preserved a great part of the antioxidant capacity and vitamin E content of the filling medium, which is of interest to the consumer. Both sunflower oil and olive oil as filling media are of great nutritional interest.

Development of

Novel zero-trans frying shortenings were formed by enzymatic transesterification by exploring a palm stearin and canola oil mixture and stearic acid as substrates. Both immobilized (Novozym 435, Lipase PS “Amano” IM) and non-immobilized (Lipomod TM 34P) enzymes were applied as biocatalysts. Palmitic acid, the fatty acid which defines the proper type of crystal formation, was present at the 15% level in the reaction mixtures. The novel structured lipids had comparable physical properties and offered similar frying performance to those of commercial shortening. Needle-shaped crystals were predominant both in the transesterification products and the commercial frying shortening. Furthermore, solid fat content profiles of the zero-trans structured lipids produced by Novozym 435 and Lipase PS “Amano” IM were close to those of the commercial shortening.

Effect of Frying on Physicochemical and Sensory Properties of Potato Chips Fried in Palm Oil Supplemented with Thyme and Rosemary Extracts

Quality parameters of potato chips (flat and serrated) fried either in palm oil (PO) alone or containing natural (thyme (TPO) and rosemary (RPO) extracts) and synthetic BHT (BPO) antioxidants were evaluated during storage period. The free fatty acid and peroxide values of chips fried in PO (control) were found between 0.18 and 0.21% to 1.00 and 1.04 meqO₂/kg during the first storage month, respectively. However, these values were 0.07-0.10% and 0.55-0.90 meqO₂/kg for chips fried in TPO, respectively. The water contents increased when storage time increased from 1 to 7 month and their values changed between 0.49 and 1.95% (flat potato chips in BPO) and between 0.88 and 1.24% (serrated potato chips in TPO). The total trans-fat contents were 0.13% (serrated potato chips in BPO) and 0.35% (both flat and serrated potato chips in PO) at the start of storage. The total trans-fat content after 7 months were 0.13% (PO fried flat and serrated potato chips) and 0.17% (serrated potato chips fried in BPO, TPO and RPO). The acrylamide contents varied between 152 (serrated potato chips in PO) and 540 µg/kg (flat potato chips fried in RPO) at the beginning of storage. However, the acrylamide contents changed during 7^th storage month and ranged from 182 (serrated potato chips in PO) to 518 µg/kg (flat potato chips in RPO). Among fatty acids, while palmitic acid are determined between 37.14 (flat chips in PO) and 41.60% (serrated chips in TPO), oleic acid varied between 30.0 (flat chips in RPO) and 33.00% (serrated chips in PO). Sensory evaluation showed that PO containing antioxidants showed better consumer preference for potato chips until the end of storage.

Sensory Shelf Life Estimation of Novel Fortified Blended Foods Under Accelerated and Real-Time Storage Conditions

Fortified blended foods (FBFs), a staple of food aid around the world, must maintain desirable characteristics for long periods of storage. This study estimated the shelf life of FBFs, including a traditional FBF (nonextruded corn soy blend plus [CSB+]) and 13 novel extrusion cooked FBFs. All products were stored under accelerated and real-time environments (real time = 30 °C and 65% relative humidity [RH], accelerated = 50 °C and 70% RH based on a Q₁₀ factor of 2). Products were made into porridges and evaluated by a descriptive sensory panel for five times in each shelf life condition. Rancid and painty sensory characteristics were key determining factors for shelf life. Real-time (RT) and accelerated shelf life (ASL) testing agreed that most novel extrusion cooked FBFs had shelf lives of at least 2 years, which is comparable to current CSB+. However, ASL testing failed to predict RT shelf life of two novel FBFs, which were estimated by RT testing to have a 2+ year shelf life. The results indicated that novel extrusion cooked FBFs have high potential for use as alternative complementary food and maintain quality for long storage periods. It is essential to conduct RT testing parallel with ASLT testing, especially for new products, to obtain a more precise estimation of products' shelf life. PRACTICAL APPLICATION: These findings show that extrusion cooked novel fortified blended foods made with extrusion generally can last up to or exceeding 24 months at ambient conditions as measured either real-time or under accelerated conditions. This is plenty of time for storage, shipping, distribution, and home storage of such products by recipients. Thus, there should be no concerns about shelf life of these products for international distribution.

A novel antioxidant: 6,6'-(butane-1,1-diyl)bis(4-methylbenzene-1,2-diol)

A novel compound, 6,6'-(butane-1,1-diyl)bis(4-methylbenzene-1,2-diol) (BMB), was synthesized through an acid-catalyzed condensation reaction between 4-methylcatechol (HPC) and butyraldehyde. When evaluated by the Rancimat and deep frying methods, BMB exhibited a stronger antioxidant activity than TBHQ. Its DPPH radical scavenging activity was also fairly higher than TBHQ, but lower compared to its mother phenol, HPC, due to its relative ease of binding DPPH•. BMB had the strongest scavenging ability of the 4-methylcatechol analogues reported to date. It could be used effectively to retard lipid peroxidation in both moderate and high temperature food preparations.

Effect of the phytochemicals curcumin, cinnamaldehyde, thymol and carvacrol on the oxidative stability of corn and palm oils at frying temperatures

Several active components naturally available in plants are strongly considered as good antioxidants to retard the lipid oxidation. Response surface methodology was used to investigate the effects of frying temperature (150-180 °C) and concentration of four plant-based active components (60-350 mg/kg oil); curcumin, cinnamaldehyde, thymol and carvacrol on oxidative stability of corn and palm oils. According to induction time values, the stability of oils drastically decreased with increasing temperature. Curcumin and cinnamaldehyde showed no significant effect (p > 0.05) on both oils. Carvacrol significantly increased induction times of corn and palm oils, but thymol was effective in palm oil only (p < 0.05). An actual frying experiment was carried out with only corn oil to confirm efficiency of carvacrol. The free fatty acid (%), peroxide value (meq/kg), para-anisidine, and total polar component values (%) of the fresh oil were 0.080, 2.55, 2.85, and 7.5, respectively. These values changed to 0.144, 1.47, 12.01, 10.0, respectively for the control oil; 0.138, 2.27, 11.49, 10.0 for BHT-added oil; 0.132, 1.42, 5.66, 9.5 for carvacrol-added oil after 30 frying cycles. Therefore, carvacrol could be considered as a good alternative to BHT for preservation of oils at frying temperatures.

Simultaneous Analysis of Tertiary Butylhydroquinone and 2-tert-Butyl-1,4-benzoquinone in Edible Oils by Normal-Phase High-Performance Liquid Chromatography

During the process of antioxidation of tertiary butylhydroquinone (TBHQ) in oil and fat systems, 2-tert-butyl-1,4-benzoquinone (TQ) can be formed. The toxicity of TQ was much more than that of TBHQ. In the work, a normal-phase high-performance liquid chromatography (NP-HPLC) method for the accurate and simultaneous detection of TBHQ and TQ in edible oils was investigated. A C18 column was used to separate TBHQ and TQ, and the gradient elution solutions consisted of n-hexane containing 5% ethyl acetate and n-hexane containing 5% isopropanol. The ultraviolet (UV) detector was set at dual wavelength mode (280 nm for TBHQ and 310 nm for TQ). The column temperature was 30 °C. Before the NP-HPLC analysis, TBHQ and TQ were first extracted by methanol, subjected to vortex treatment, and then filtered through a 0.45 μm membrane filter. Results showed that linear ranges of TBHQ and TQ were both within 0.10-500.00 μg/mL (R(2) > 0.9999). The limit of detection (LOD) and limit of quantification (LOQ) of TBHQ and TQ were below 0.30 and 0.91 μg/mL and below 0.10 and 0.30 μg/mL, respectively. The recoveries of TBHQ and TQ were 98.92-102.34 and 96.28-100.58% for soybean oil and 96.11-99.42 and 98.83-99.24% for lard, respectively. These results showed that NP-HPLC can be successfully used to analyze simultaneously TBHQ and TQ in the oils and fats.

Influence of natural and synthetic antioxidants on the degradation of Soybean oil at frying temperature

The effect of several natural and synthetic antioxidants to retard the formation of polar compounds and thermo-oxidation at prolonged frying temperatures was studied. Antioxidants, including butyl hydroxyl toluene (BHT), ter-butyl hydroxyquinone (TBHQ), α- and γ-tocopherols, tocopherol mixture (α, β, γ and δ), sesamol, β-sitosterol, β-sitostanol, γ-oryzanol, curcumin, rosemary extract and sucrose acetate isobutyrate (SAIB) were tested in refined soybean oil without added any additives recovered from refinery. Rosemary extract and SAIB were showed a considerable effect on both polar compound formation and secondary oxidation. These compounds increased the oxidative stability of oil for more than 30 % compared to conventional synthetic antioxidants. Oils treated with SAIB showed higher color retention after 6 h heating compared to the oils added with BHT, TBHQ and tocopherols. Curcumin, sesamol and γ-oryzanol showed higher antioxidant potential compared to other antioxidants. Preliminary results obtained from this study have clearly demonstrated that SAIB and rosemary extracts are more commercially viable antioxidants to increase the stability of frying oils.

2,6-Di-Tert-Butyl-Hydroxytoluene and Its Metabolites in Foods

2,6-Di-tert-butyl-hydroxytoluene (BHT, E-321) is a synthetic phenolic antioxidant which has been widely used as an additive in the food, cosmetic, and plastic industries for the last 70 y. Although it is considered safe for human health at authorized levels, its ubiquitous presence and the controversial toxicological data reported are of great concern for consumers. In recent years, special attention has been paid to these 14 metabolites or degradation products: BHT-CH₂ OH, BHT-CHO, BHT-COOH, BHT-Q, BHT-QM, DBP, BHT-OH, BHT-OOH, TBP, BHQ, BHT-OH(t), BHT-OH(t)QM, 2-BHT, and 2-BHT-QM. These derived compounds could pose a human health risk from a food safety point of view, but they have been little studied. In this context, this review deals with the occurrence, origin, and fate of BHT in foodstuffs, its biotransformation into metabolites, their toxicological implications, their antioxidant and prooxidant properties, the analytical determination of metabolites in foods, and human dietary exposure. Moreover, noncontrolled additional sources of exposure to BHT and its metabolites are highlighted. These include their carryover from feed to fish, poultry and eggs, their presence in smoke flavorings, their migration from plastic pipelines and packaging to water and food, and their presence in natural environments, from which they can reach the food chain.

Virgin olive oil phenolic profile and variability in progenies from olive crosses

BACKGROUND

The progressive transformation of olive growing and the increasing demands for high-quality monovarietal virgin olive oil (VOO) have triggered interest in olive breeding programs, in which the evaluation of the new genotypes is the basis for obtaining new olive cultivars. In this work, the phenolic composition of VOOs from two progenies from crosses between 'Arbequina', 'Arbosana' and 'Sikitita' has been evaluated along two years.

RESULTS

A higher degree of variation was observed in segregating population as compared to genitors. The results also showed that the variability within crosses constitutes the major contribution to total variance for all considered parameters (>92% of total sum of squares). All compounds under study were present in oils obtained in both years; however, clear differences in their concentrations were observed between years.

CONCLUSION

Olive breeding can indeed provide genotypes that produce oils with improved phenolic profiles as compared to traditional cultivars. In addition, the data showed that selection as a function of tyrosol content could be achieved in only one crop year. Finally, p-coumaric acid was the unique component able to discriminate between both crop years under study.

Influence of simulated deep frying on the antioxidant fraction of vegetable oils after enrichment with extracts from olive oil pomace

The stability of the antioxidant fraction in edible vegetable oils has been evaluated during a simulated deep frying process at 180 °C. Four edible oils (i.e., extra-virgin olive oil with a 400 μg/mL overall content in naturally existing phenols; high-oleic sunflower oil without natural content of these compounds but enriched either with hydrophilic antioxidants isolated from olive pomace or with an oxidation inhibitor, dimethylsiloxane; and sunflower oil without enrichment) were subjected to deep heating consisting of 20 cycles at 180 °C for 5 min each. An oil aliquot was sampled after each heating cycle to study the influence of heating on the antioxidant fraction composed of hydrophilic and lipophilic antioxidants such as phenols and tocopherols, respectively. The decomposition curves for each group of compounds caused by the influence of deep heating were studied to compare their resistance to oxidation. Thus, the suitability of olive pomace as raw material to obtain these compounds offers an excellent alternative to the use of olive-tree materials different from leaves. The enrichment of refined edible oils with natural antioxidants from olive pomace is a sustainable strategy to take benefits from this residue.