Degradation Of Tocopherols Research Articles

Low expression of lipoxygenase 3 (LOX3) enhances the retention of kernel tocopherols in maize during storage.

Deficiency of vitamin E results in several neurological and age-related disorders in humans. Utilization of maize mutants with favourable vte4-allele led to the development of several α-tocopherol (vitamin E) rich (16-19µg/g) maize hybrids worldwide. However, the degradation of tocopherols during post-harvest storage substantially affects the efficacy of these genotypes. We studied the role of lipoxygenase enzyme and Lipoxygenase 3 (LOX3) gene on the degradation of tocopherols at monthly intervals under traditional storage up to six months in two vte4-based contrasting-tocopherol retention maize inbreds viz. HKI323-PVE and HKI193-1-PVE. The analysis revealed significant degradation of tocopherols across storage intervals in both the inbreds. Lower retention of α-tocopherol was noticed in HKI193-1-PVE. HKI323-PVE with the higher retention of α-tocopherol showed lower lipoxygenase activity throughout the storage intervals. LOX3 gene expression was higher (~ 1.5-fold) in HKI193-1-PVE compared to HKI323-PVE across the storage intervals. Both lipoxygenase activity and LOX3 expression peaked at 120 days after storage (DAS) in both genotypes. Further, a similar trend was observed for LOX3 expression and lipoxygenase activity. The α-tocopherol exhibited a significantly negative correlation with lipoxygenase enzyme and expression of LOX3 across the storage intervals. HKI323-PVE with high tocopherol retention, low -lipoxygenase activity, and -LOX3 gene expression can act as a potential donor in the vitamin E biofortification program. Protein-protein association network analysis also indicated the independent effect of vte4 and LOX genes. This is the first comprehensive report analyzing the expression of the LOX3 gene and deciphering its vital role in the retention of α-tocopherol in biofortified maize varieties under traditional storage.

Influence of storage duration on retention of kernel tocopherols in vte4-based biofortified maize genotypes

The degradation of tocopherols during post-harvest storage poses a challenge to their efficacy in addressing vitamin E deficiency (VED), a problem faced by humans. Here, a diverse panel of vte4 gene-based inbreds along with their wild-type genotypes was analyzed to study genetic variation for retention of tocopherols during conventional storage (temperature: 25–30 °C and humidity: 42–82%) for six months. vte4-based inbreds possessed 2-fold higher tocopherol fractions over normal inbreds immediately after harvest [0 days after storage (DAS)]. High genetic variation for retention of tocopherol fractions viz. α-tocopherol (17.20–45.44%), γ-tocopherol (30.46–44.03%), and δ-tocopherol (20.51–33.87%) was observed after six months of storage (180 DAS) among vte4-based inbreds, whereas, normal inbreds possessed comparatively low genetic variation [α-tocopherol (8.54–12.29%), γ-tocopherol (23.74–27.48%) and δ-tocopherol (15.88–23.68%)]. A major fraction of α-tocopherol, and δ-tocopherol was lost during the last three months of storage (3rd month: 31.00% loss, 6th month: 75.22%), meanwhile, γ-tocopherol showed comparatively slower degradation (3rd month: 31.62% loss, 6th month: 65.56% loss). HKI323-PVE (45.44%), HKI1105-PVE (24.08%), HKI161-PVE (23.17%) and HKI1128-PVE (22.73%) were the promising maize inbreds with higher retention of α-tocopherol at 180 DAS. These potential inbreds can be effectively used as valuable genetic resources in the biofortification programme, and the contrasting genotypes distinctly differing for retention of tocopherols can be used to map the loci for higher retention of tocopherols.

Impact of low oxygen storage on post-storage quality of pasteurized walnut (Juglans regia L.) kernels

Walnut (Juglans regia) kernels were obtained from two facilities, each using a different method for pasteurization to achieve a log 4 and log 5 reduction in the bacterial load on the kernel surface. Continuous pasteurization utilized high temperature steam applied for a short period, and batch pasteurization utilized lower temperature steam applied in a pressurized chamber for a longer period. Log 4 and 5 walnut kernels from both treatment methods were stored at 20 °C in air or sealed in bags with a low oxygen transmission rate, and an oxygen absorbing sachet was inserted to reduce internal oxygen concentrations to < 0.5 %. After pasteurization and packaging, walnuts were stored and evaluated periodically for peroxide value, hexanal, free-fatty acids, and total tocopherols. These objective quality measures were compared to descriptive sensory analyses of walnut taste, texture, and aroma conducted by a trained sensory panel. Continuous pasteurization of walnuts increased the rate of oil oxidation and loss of total tocopherols, but storage of walnuts in low oxygen atmospheres mitigated some of the negative quality impacts. Continuous pasteurization resulted in an immediate decreased in total tocopherols prior to storage under low oxygen atmospheres; however, low oxygen storage reduced subsequent losses in tocopherols. Batch pasteurization did not enhance quality degradation as compared to unpasteurized controls, but storage under low oxygen reduced oil oxidation and slowed the degradation of total tocopherols, as typically observed during walnut storage.

Investigation of roasting and photo-oxidative stability of cold-pressed peanut oil: Lipid composition, quality characteristics, and antioxidant capacity

In this study, the effect of conventional roasting and the photo-oxidative stability of two cold-pressed peanut oil varieties (Virginia and Valencia) were investigated. Changes in the concentrations of the fatty acids (including trans isomers), minor components, nutritional quality, and antioxidant capacity were analyzed and compared. The evolution of the oxidation status was measured by peroxide value (PV), acid value (AV), p-anisidine value (p-AnV), UV-spectrophotometric indexes (E232 and E270), total oxidation value (TOTOX), and browning index (BI). Results showed a slight change in AV, while relevant primary and secondary lipid oxidation was detected, leading to an increase in PV, p-AnV, as well as E232 and E270 indexes during roasting and photo-oxidation. Furthermore, exposure to UV light resulted in a remarkable degradation of tocopherol (71.67–100%), while phytosterols were reduced by 0.16–6.68%. Roasting, on the other hand, resulted in a significant increase (p < 0.05) in the content of phytosterols, tocopherols, chlorophyll, and carotenoid as well as antioxidant activity in peanut oil. In addition, Maillard reaction products (estimated by BI) also increased with roasting; afterward, these compounds gradually declined with UV light exposure. As for the fatty acid profile and nutritional indicators, a noticeable difference was observed between unroasted and roasted peanut oils throughout photo-oxidation.

Tocopherol degradation and lipid oxidation during storage of Chenopodium quinoa

Chenopodium quinoa serves as an essential source of dietary lipids and tocopherols. The current study evaluated the stability of tocopherols and the occurrence of lipid oxidation in quinoa seeds, sprouts, and flakes during storage. Quinoa samples (seed flour, sprout flour, flakes) were stored at different temperatures (0 °C, 25 °C, 35 °C); changes in their tocopherol profile and the progress of lipid oxidation were evaluated for 180 days. Tocopherol concentration was measured using HPLC, and the degradation of major homologues was modeled using first and second order kinetics. γ- tocopherol (107–135 µg g-1 dwb) was present in highest concentration in fresh products, followed by α- tocopherol (19.3–32.4 µg g-1 dwb) and δ- tocopherol (1.6–2.3 µg g-1 dwb). Storage at 25 °C and 35 °C resulted in a drastic reduction of tocopherols; out of the three products, seed flour and flakes retained < 50 % of γ- and α- tocopherols after 180 days, while sprout flour showed better retention at both temperatures. The investigation of lipid oxidation revealed the presence of 13 volatile compounds that were formed due to oxidation of linoleic, linolenic, and oleic acids. Hexanal, a key indicator of oxidation, significantly increased at 35 °C, demonstrating that temperature during storage represents a critical factor in maintaining the quality of quinoa products.

Effect of Heating Temperature of High-Quality Arbequina, Picual, Manzanilla and Cornicabra Olive Oils on Changes in Nutritional Indices of Lipid, Tocopherol Content and Triacylglycerol Polymerization Process.

The aim of the study was to determine the stability and heat resistance of extra premium olive oil. The study material consisted of six extra virgin olive oils (EVOO) obtained from Spain. Four samples were single-strain olive oils: Arbequina, Picual, Manzanilla, and Cornicabra. Two samples were a coupage of Arbequina and Picual varieties: Armonia (70% Arbequina and 30% Picual) and Sensation (70% Picual and 30% Arbequina). Olive oil samples were heated at 170 °C and 200 °C in a pan (thin layer model). In all samples, changes in indexes of lipid nutritional quality (PUFA/SFA, index of atherogenicity, index of thrombogenicity, and hypocholesterolemic/hypercholesterolemic ratio), changes in tocopherol, total polar compounds content, and triacylglycerol polymers were determined. Heating olive oil in a thin layer led to its degradation and depended on the temperature and the type of olive oil. Increasing the temperature from 170 to 200 °C resulted in significantly higher degradation of olive oil. At 200 °C, deterioration of lipid nutritional indices, total tocopherol degradation, and formation of triacylglycerol polymers were observed. A twofold increase in the polar fraction was also observed compared to samples heated at 170 °C. The most stable olive oils were Cornicabra and Picual.

Oxidation of Cyclo‐Lino Peptides in Linseed Oils during Storage

AbstractLinseed oil is appreciated for its high level of linolenic acid. In order to avoid oxidation, the precious storage lipids are protected in the seeds by lignans, tocopherols, and cyclo‐lino peptides. Oxidation of specific cyclo‐lino peptides can be attributed to the formation of a bitter off‐taste in cold pressed linseed oils. A complete degradation of tocopherols and of intact cyclo‐lino peptides CLO, ‐M, ‐N, ‐L, and ‐B to oxidized forms is observed with intermediate oxidation products of the peptides containing methionine oxidized to methionine sulfoxide and further to methionine sulfone during a storage period of 25 d at 60 °C in the dark and of 14 weeks at day light and room temperature. The peroxide value increases to 255 meq O2 kg−1 at the same time. However, during storage at room temperature in the dark only a very limited decrease of the initial tocopherols content of 400 mg/100 g is observed contrasted by an increase of the peroxide value to about 50 meq O2 kg−1 and a more or less complete degradation of cyclo‐lino peptides. While at 6 °C in the dark all oxidation parameters keep stable. The tocopherols and cyclo‐lino peptides show different and independent degradation during these storage conditions.Practical Application: This work elucidates the role of cyclo‐lino peptides and tocopherols in the complex reactions taking place during oxidation of linseed oil and enables a first evaluation of the antioxidative power of cyclo‐lino peptides at different storage conditions.

Inhibition Effect of Oryzanol on the Degradation of Tocopherol and the Oxidation Kinetic of Rice Bran Oils with Different Content of Oryzanol and Tocopherol

AbstractThe purpose of this study is to investigate the inhibitory effect of oryzanol on the degradation of tocopherol during heating of rice bran oil at 110 and 170 °C and the oxidation kinetics of rice bran oil. Results demonstrate the degradation of oryzanol and tocopherol in rice bran oils follow the first‐order kinetic models. The higher concentration of oryzanol has no inhibitory effect on the degradation of tocopherol when the concentration of tocopherol in rice bran oil is 500 mg kg−1. However, when the concentrations of tocopherol reach 1500 and 2000 mg kg−1, higher oryzanol concentration make the inhibitory effects on the degradation of tocopherol more pronounced. Compared with rice bran oils containing lower levels of tocopherol and oryzanol, rice bran oils containing higher levels of tocopherol and oryzanol have higher activation energy (Ea), activation enthalpy (ΔH), and activation entropy (ΔS) and a larger temperature acceleration factor (Q10), which indicate that higher levels of oryzanol and tocopherol promote the thermal oxidation of rice bran oil. Therefore, in the compound application of tocopherol and oryzanol in rice bran oil, the influence of its content on the thermal oxidation of oil should be fully considered.Practical Application: This study may be useful for the grain and oil industry because studies on the degradation kinetics of oryzanol and tocopherol during heating of rice bran oil and oxidation kinetics of rice bran oil are still lacking in the literature. The results of this study is valuable for predicting and evaluating the oxidation process and nutritional properties of rice bran oils under various thermal oxidation conditions.

Effect of superheated steam treatment and extrusion on lipid stability of black soybean noodles during storage

This study investigated the effect of superheated steam treatment (SST) and extrusion treatment (ET) on the changes of lipids in black soybean noodles (BSN) during storage. Degradation of lipids and formation of volatile compounds were closely related to the endogenous lipid-degrading enzyme activity. Both SST and ET could effectively inactivate lipase, lipoxygenase and peroxidase activity in black soybeans, and thus in the BSN. The content of polyunsaturated fatty acids decreased by 43.6% in non-heat-treated BSN during 7-week storage, whereas the reduction was only 23.0% and 20.7% in SST-190 °C and ET-130 °C groups, respectively. The degradation of tocopherols and tocotrienols, and formation of volatile compounds in the BSN was greatly inhibited during storage by the two heat processes, and ET seems to be more effective. In conclusion, both SST and ET were able to increase the lipid stability of BSN by inhibit the activity of lipid-degrading enzymes. This study could also provide more knowledge that assists to develop high quality of black soybean food products.

Green Tea Extract Enhances the Oxidative Stability of DHA-Rich Oil.

Docosahexaenoic acid (DHA) is one of the most important omega-3 polyunsaturated fatty acids, with proven health-promoting properties. However, oils with a very high content in DHA (DHAO) are extremely susceptible to oxidation, which affects shelf stability and limits incorporation in food products. Green tea extracts (GTE) are potential candidates for the protection of these oils, but their use in such oils has not been previously reported. This study investigated the effect of GTE (160 ppm, 400 ppm, 1000 ppm) and α-tocopherol (80 ppm, 200 ppm, 500 ppm) on the oxidative stability of a DHAO over a 9-week storage at 30 °C. The oxidative status was monitored during storage by the measurement of peroxide value (PV) and p-anisidine value (p-AV). Changes in eicosapentaenoic acid (EPA) and DHA content, as well as in catechins and tocopherol contents, were also evaluated. The addition of GTE enhanced the oxidative stability of DHAO by reducing the formation of peroxides and secondary oxidation products, whereas α-tocopherol had no significant effect on the PV of oil during storage but led to a significantly higher p-AV. The EPA and DHA content of DHAO was stable in GTE-supplemented samples whereas a decrease was observed in the control and α-tocopherol-supplemented samples. GTE also delayed the degradation of tocopherols initially present in the oil, while catechins resulting from the addition of GTE decreased progressively during the storage period.

Influence of oryzanol and tocopherols on thermal oxidation of rice bran oil during the heating process at Chinese cooking temperatures

Natural antioxidants are important for the stability and nutritional properties of oils. Therefore, this study explored the stability of rice bran oil with different ratios of oryzanol to tocopherols during heating at 110 °C and 170 °C. In addition, the relationship between the loss of oryzanol and tocopherols and physicochemical indexes was investigated through multiple linear regression and Pearson correlation analyses. The results showed that the optimal ratio of oryzanol to tocopherols was 8:1, the oxidation stability index of rice bran oil reached 10.26 h and the formation of free fatty acids and secondary oxidation products was markedly inhibited. Additionally, the degradation of tocopherols in rice bran oil followed the first-order kinetic model. Moreover, both oryzanol and tocopherols were responsible for the antioxidant properties of rice bran oil although oryzanol had a bigger contribution. Therefore, these results may provide interesting insights into the appropriate ratio of these minor compounds in oil products. Furthermore, the establishment of a multiple linear regression model may also be valuable in exploring the antioxidant behavior of oryzanol and tocopherols during heating.

Degradation of aflatoxins and tocopherols in peanut (Arachis hypogaea): Effect of aflatoxin type, time and temperature of roasting

At the present time, aflatoxins are believed as one of the most harmful mycotoxins to people, and nuts including peanuts are one of the main foods for human exposure to mycotoxins. The aim of this study was to consider the effect of roasting conditions on the extent of the degradation of aflatoxins and nutritional changes (e.g., to the α- and γ-tocopherols) of peanuts. Samples of peanuts were contaminated with three initial concentrations of 2.5, 5 and 10 ng/g aflatoxin B1, B2, G1 and G2, respectively and the peanuts were roasted at 120 and 150 °C for 20, 30 and 40 min. Then, the concentrations of aflatoxins B1, B2, G1 and G2 were determined by High Performance Liquid Chromatography (HPLC) and the residual concentrations of the aflatoxins were expressed as percentage of the original aflatoxin content. In addition, the amount of tocopherols was determined by HPLC. The results showed that at highest decrements of the aflatoxins occurred at the higher roasting times, temperatures and initial concentrations of the aflatoxins. Accordingly, maximum reduction of aflatoxins B1, B2, G1 and G2 i.e., 37.9%, 39.8%, 37.4% and 40.4%, respectively, occurred when the contaminated samples with initial aflatoxin concentrations 10 ng/g were heated at 150 °C for 40 min. In addition, the content of α- and γ-tocopherols were increased at both roasting temperatures (120 and 150 °C) during the initial steps of the roasting process, however the roasting time increase up to 40 min, the amount of tocopherols decreased slightly. Thus, treatment of 150 °C for 40 min, could be regarded as the best roasting treatment for peanuts.

Degradation of Tocopherol Molecules and Its Impact on the Polymerization of Triacylglycerols during Heat Treatment of Oil.

The aim of the study was to analyze the influence of the surface area to volume ratio of pressed and refined rapeseed oils on the changes in tocopherol content and polymerization of triacylglycerols during heating. In the study the pressed and refined rapeseed oil was heated at 170 °C, during 6, 12, and 18 h with three different surface area to volume (s/v) ratios (0.378, 0.189, and 0.126 cm−1). During heating, a decrease in tocopherols and increases in dimers, trimers, and oligomers of triacylglycerols were observed. However, the changes were dependent on the surface area to volume ratio used, type of oil and time of heating. The biggest changes were observed in oil with the biggest s/v ratio (0.378 cm−1), and the lowest when the s/v ratio was 0.126 cm−1. The pressed oil was characterized by faster degradation of tocopherols and slower increase of triacylglycerol polymer levels compared to refined oil.

Effect of tea catechin derivatives on stability of soybean oil/tea seed oil blend and oxidative stability of fried fish crackers during storage.

Effect of (-)-epigallocatechin gallate (EGCG) and (-)-epicatechin (EC) at different concentrations (100-300ppm) on frying stability of soybean oil blended with tea seed oil was studied. Thermal stability of the blended oil increased with the addition of EGCG and EC, especially with increasing concentrations. Frying induced degradation of tocopherols and phenolics of oils, particularly tocopherols. Incorporation of catechin derivatives could retard tocopherol decomposition and formation of polar materials. The highest frying stability was found for the oil added with EC at 300ppm. When the oil added with EC (300ppm) was used to prepare fish crackers, lowered lipid oxidation of the resulting crackers than those prepared using the control oil was noted throughout 12weeks of storage. EC could be effectively used as natural antioxidant in frying oil with carry through effect to enhance oxidation stability of the fried foods during a storage.

Bioactive lipids, antiradical activity and stability of rosehip seed oil under thermal and photo-induced oxidation

In the present report, the fatty acids, tocopherols, and sterol profiles as well as the total phenolics and carotenoids of rosehip (Rosa canina) seed oil were determined. The major fatty acids in the oil were linoleic and linolenic acids, comprising 54.80% and 23.47% of the total fatty acids, respectively. Other bioactive lipids in the oil included total tocopherols (786.3 mg/kg), total phenolics (37.97 mg/kg) and total carotenoids (218.8 mg/kg). Rosehip oil was rich in γ-tocopherol (472.0 mg/kg) and β‑sitosterol (78.0% of total sterols). The DPPH· (2,2′-diphenyl-1-picrylhydrazyl) radical scavenging activity of the oil showed 1.08 mg α-tocopherol/g oil and 4.18 μmol TEAC (Trolox equivalent antioxidant capacity)/g oil, respectively. The ABTS+ (2,2′-Azino-bis-3-ethylbenzothiazoline-6-sulphonic acid) radical scavenging activity of the oil showed 1.00 mg α-tocopherol/g oil and 3.02 μmol TEAC/g oil, respectively. The induction period (IP) of the oil was 3.46 h for the Rancimat test (110 °C), while the IP of oil in differential scanning calorimetry (DSC) test (100-150 °C) ranged between 0.26 and 58.06 min. The oxidative stability of the oil was determined under thermal and photo oxidation conditions. The progression of oxidation at 30 °C (under UV light) and at 60 °C (in the dark) was followed by recording the ultraviolet absorption (K232 and K270) and degradation of total tocopherols, γ-tocopherol and total carotenoids. Rapid deterioration occurred in the oil stored under UV light conditions. The information provided in the present work is of importance for using rosehip seed oil in different food and non-food applications.

Lipid oxidation-related characteristics of gim bugak (Korean fried cuisine with Porphyra) affected by frying oil.

The effect of frying oil on the lipid oxidation, antioxidants, and in vitro antioxidant activity of gim bugak was studied. Bugak was prepared by pan-frying at 180°C in unroasted sesame, soybean, extra virgin olive, or palm oil. The degree of lipid oxidation based on conjugated dienoic acid and p-anisidine values was higher in the bugak fried in soybean or sesame oil with high contents of polyunsaturated fatty acids and tocopherols. However, the oil oxidation was lower in olive and palm oils, which showed higher degradation of tocopherols and polyphenols than in sesame or soybean oil during frying. Although the bugak fried in palm oil contained less antioxidants than that fried in soybean or sesame oil, the in vitro antioxidant activity was not different (p>0.05). Results suggest that palm oil can replace unroasted sesame oil for the preparation of gim bugak with improved lipid oxidative stability and health functionality.

Comparative study of crude and refined kenaf (Hibiscus cannabinus L.) seed oil during accelerated storage.

This study assessed the changes of antioxidant activity and bioactive compounds of crude and refined kenaf seed oil during accelerated storage at 65°C for 24 days. 2,2-Diphenyl-1-picrylhydrazyl and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) radical scavenging assays were used to determine their antioxidant activity. The changes of phenolic, tocopherol, and phytosterol contents during the storage were also studied. The phenolic content and antioxidant activity of refined oil were significantly lower than those of crude oil after the accelerated storage. There was a decrease of 72.5% tocopherol content and 31.1% phytosterol content in the crude oil and a decrease of 67% tocopherol content and 12.1% phytosterol content in the refined oil during the accelerated storage. There was no significant difference in tocopherol and phytosterol contents for crude and refined oils after the storage. The rate of degradation of tocopherol and phytosterol contents in refined oil was slower than that in crude oil during the storage.

Degradation of fatty acids and tocopherols to form tocopheryl quinone as risk factor during microwave heating, pan‐frying and deep‐fat frying

We investigated degradation of tocopherols to form tocopheryl quinones (TQ) and cytotoxic γ‐tocopheryl quinone in oils and French fries during microwave heating, pan‐frying and deep‐fat frying. We proved that the microwave oven caused rapid increase of oil temperature, with the consequence of two to three times greater degradation of fatty acids and tocopherols than pan‐frying and deep‐fat frying. Pan‐frying with sunflower oil caused three‐time greater formation of fatty acids polymers, compare with rapeseed oil. The gentlest one was deep‐fat frying, which caused two times slower formation of fatty acid hydroperoxides and tocopheryl quinones in 900 g of oil. We found that not only the quantity but also the type of oil had critical effect on the formation of cytotoxic γ‐tocopheryl quinone. During 50 min of pan‐frying in rapeseed oil, 22 mg/kg of γ‐tocopheryl quinones was formed, of which 5–7 mg/kg penetrated into the homemade French fries. While the deep‐fat frying technique generated only 6 mg/kg of γ‐tocopheryl quinones in rapeseed oil. The rapid microwave heating caused formation of 8 mg/kg of γ‐tocopheryl quinones within 10 min. The emergence of γ‐tocopheryl quinones during culinary preparation of food has not yet been explored.Practical applications: Although an extensive research have been conducted in the area of microwave heating of foods, this is the first report about formation of cytotoxic γ‐tocopheryl quinone in microwave‐heated rapeseed oil. Formation of this reactive compound was also confirmed during frying process. The most γ‐tocopheryl quinone was formed during pan‐frying and subsequently entered into fried food. It was observed that the amount of oil used for frying has a major impact on slowing formation of cytotoxic γ‐tocopheryl quinone and other tocopherols and fatty acids degradation product.Formation of health‐promoting α‐tocopheryl quinone and cytotoxic γ‐tocopheryl quinone during pan‐frying.

Effects of gardenia seed, green tea, and cactus pear in rice batter on the chemical quality of lotus root bugak and frying oil.

This study investigated the effects of the addition of gardenia seed, green tea, or cactus pear (Opuntia ficus-indica) to rice batter at 10% on the lipid oxidation, pigments, antioxidants, and antioxidant activity of lotus root bugak and frying oil. Lipid oxidation was evaluated based on the conjugated dienoic acid and p-anisidine values. Lipid oxidation and tocopherol degradation were significantly reduced in the gardenia seed-added bugak and frying oil, whereas the cactus pear-added bugak and frying oil showed an increase. The addition of green tea had no significant effects on the lipid oxidation of bugak and frying oil. The in vitro antioxidant activity of lotus root bugak significantly increased with the addition of gardenia seed, green tea, or cactus pear. The results suggested that green tea and gardenia seed could improve the health and food functionality of antioxidation for lotus root bugak, respectively.

Protective role of vacuum vs. atmospheric frying on PUFA balance and lipid oxidation

Abstract The effect of vacuum frying processing on proximate composition, fatty acid profile, oxidative status and sensorial properties of fish patties, was evaluated as compared with conventional (atmospheric) frying. Vacuum frying procedure was carried out at 80 mmHg (water boiling point: 42 °C) and oil temperature (107 °C) determined to obtain an equivalent thermal driving force (Δ65 °C) of that of the atmospheric frying conditions used (165 °C). Frying times of 2, 4, 6, 8 and 10 min were investigated. Vacuum frying significantly prevented degradation of EPA (Eicosapentaenoic acid) and DHA (Docosahexaenoic acid), reducing the polyene index and maintaining a lower ω6/ω3 fatty acid ratio in samples, while no significant differences with conventional frying in total oil content were observed. The use of vacuum also reduced formation of peroxides and carbonyl derivatives. Tocopherol levels decreased in all samples regardless of the frying conditions used, although vacuum-fried samples maintained higher tocopherol levels after processing. These samples also showed higher lightness and lower a* and b* values, which can be associated to lower non-enzymatic browning levels. These results support the applicability of vacuum frying technology for fish patties, since it prevents colour changes, improves juiciness and reduces oxidation when compared to conventionally (atmospheric) fried counterparts. Industrial relevance Consumers are increasingly aware of the link between food and health, maintaining a high demand for healthy products. In this regard, consumption of fatty fish, with healthy properties widely known, is lower than recommended by health authorities, especially in children. Novel processing technologies focused on increasing the appealing of products based on fatty fish can help in ameliorating this deficient consumption. Vacuum frying is a promising way of obtaining attractive products, due to some product modification after the deep-fat frying process, and yet retaining natural colour, juiciness and healthy properties to a high extent. Vacuum frying allows reducing ω3 fatty acids and tocopherol degradation, differentiating fish products so obtained, which can be launched into the market and benefit from this technology. Compared to conventional frying, the results are better nutritional and sensory properties in a final product.