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This study shows the possibility of using gallic acid (GA) and/or methyl gallate (MG) accompanied by phosphatidylcholine (PC) instead of tert-butylhydoquinone (TBHQ) for frying purposes. The antioxidants and PC were added in the concentrations of 1.2 mM and 500-2000 mg/kg, respectively. Oxidative stability index (OSI) and the kinetics of change in conjugated dienes (LCD), carbonyls (LCO), and acid value (AV) were used to assess the antioxidative treatments. GA alone and GA/MG (50:50) plus PC at 2000 mg/kg yielded the same OSI as that of TBHQ (18.4 h). The latter was of the highest frying performance in preventing the formation of LCD (rn = 0.0517/h and tT = 10.6 h vs. rn = 0.0976/h and tT = 4.5 h for TBHQ), LCO (rn = 0.0411/h and tT = 12.7 h vs. rn = 0.15/h and tT = 4.3 h for TBHQ), and hydrolytic products (AVm = 37.8 vs. 24.0 for TBHQ); rn: normalized the maximum rate of LCD/LCO accumulation; tT: the time at which the rate of LCD/LCO accumulation is maximized; AVm: quantitative measure of hydrolytic stability.

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The present work shows the possibility of use of gallic acid (GA) and methyl gallate (MG) as natural antioxidants replacing the powerful synthetic antioxidant TBHQ in frying process. Oxidative stability index (OSI) and the kinetics of change in lipid-peroxidation conjugated dienes (LCD), carbonyls (LCO), and acid value were adopted for the evaluation purposes. GA alone (1.2 mM) and in combination with MG (75:25) provided OSI values comparable to that of TBHQ (18.5-19.0 h). The GA/MG 75:25 exerted a frying performance quite better than TBHQ (rn = 0.1351 vs. 0.1784 h-1) in preventing the LCD formation. From the LCO formation standpoint, the GA/MG 75:25 (rn = 0.0758 h-1) and then MG (rn = 0.1004 h-1) provided better performances than TBHQ (rn = 0.1216 h-1). Lipid hydrolysis was also inhibited well by GA (AVm = 8.6) and GA/MG 75:25 (AVm = 7.9), respectively (AVm = 9.2 for TBHQ).

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BACKGROUND: Oleogels can be used in the food industry to reduce the consumption of solid fat in the human diet and diminish some of the industrial-technological issues of using oil instead of fat. Regarding the structural weakness of neat monoglyceride oleogel and the waxy mouthfeel of pure carnauba wax oleogel, as a result of the high melting and crystallization points, the present study aimed to diminish these defects. RESULTS: Carnauba wax (CBW) was used as a co-gelator with distilled monoglyceride (DMG) at different weight ratios (100:0, 85:15, 70:30, 55:45, 40:60, and 0:100) (DMG: CBW) and two total gelator concentrations (50 and 100 g kg-1 ) to improve the DMG oleogel characteristics. The addition of CBW strengthened the DMG network and decreased the polymorphic transition. Thermal analysis showed just co-crystallization at the 85:15 ratio, whereas, in the other combinations, high melting components of CBW crystalized at first. As a result of the crystal homogeneity and long-time development, the oleogel properties improved at the 85:15 ratio. The low concentration of CBW and the formation of the eutectic system were efficient in the waxy mouthfeel reduction of oleogel at the 85:15 ratio in food applications. CONCLUSION: The DMG/CBW oleogel at the 85:15 ratio, with better structural and sensorial properties than DMG and CBW oleogels, respectively, has the potential for use instead of fat in food formulations. © 2023 Society of Chemical Industry.

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Kinetics of change in total polar compounds (TPC), carbonyl value (CV), and conjugated diene value (CDV) were simultaneously investigated during the frying of potato strips in eight oil samples at 170 °C. The CDV at the turning point of the sigmoidal kinetic curves (CDVT) with an average of ~19 mmol/L, which was almost equivalent to the TPC and CV of ~14% and ~24 µmol/g, respectively, was found to be as a sensory cut-off value for rejection. To discard frying oils from a toxicological standpoint, the CDV at the mean of the times required to reach the CDVT and the CDVmax with an average of ~28 mmol/L (almost equivalent to the TPC and CV of ~22% and ~41 µmol/g, respectively) was determined as the corresponding cut-off value.

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The present study introduced for the first time a sigmoidal function regarding the change in lipid-peroxidation carbonyls over time, providing a number of helpful kinetic parameters to more reliably evaluate the secondary oxidation of lipid systems. The sigmoidal function was of excellent goodness of fit (R2 > 0.99) in the non-inhibited and inhibited (in the presence of the antioxidant TBHQ) fatty acid compositions (sunflower and olive oils) at 80 and 100 °C. The calculated kinetic parameters were able to significantly differentiate among the oxidizing systems exposed to the experimented intrinsic/extrinsic factors. The new methodology developed in this study enabled us to more quantitatively indicate the resistance of lipid systems to the production of one of the most important destructive compounds from nutritional and sensory standpoints.

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The activity and capacity of gallic acid (GA) and methyl gallate (MG) in scavenging DPPH· were determined in different solvents. Based on the bimolecular rate constants k2, both antioxidants showed highest activities in EtOH, followed by in MeOH, t-BuOH, MeCN, 2-PrOH, acetone, THF, ethyl acetate, and 1,4-dioxane. GA indicated better activities (k2 value, M-1 s-1) than MG in the alcoholic solvents (51-1939 vs. 25-1530) and in MeCN (203 vs. 187) whereas MG was of higher activities in the polar aprotic solvents (1.7-41 vs. 1.6-13). The highest stoichiometries for GA vs. MG were in 2-PrOH (6.67 vs. 5.37), followed by EtOH (5.84 vs. 4.57), MeOH (5.34 vs. 3.8) ~ acetone (5.02 vs. 4.44), MeCN (3.68 vs. 3.05) ~ t-BuOH (3.14 vs. 2.99), THF (2.34 vs. 2.2), ethyl acetate (1.2 vs. 0.93), and 1,4-dioxane (0.34 vs. 0.35).

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Simultaneous evaluations over the whole practical range of peroxidation, including the initiation and propagation phases, provide more informative and reliable data than single-parameter analyses being mostly employed only over the course of the initiation phase. Besides an overview on the dominant mechanisms governing the initiation and propagation phases, this article highlights a number of unifying parameters that represent inclusively the two phases. Then, the reliable method to calculate induction period and critical reverse micelle concentration of lipid hydroperoxides as the two interstitial parameters when transitioning from the initiation to the propagation phase is reviewed. Next, a reconsidered form of the conventional methodology on the kinetics of chain-breaking antioxidants is presented. After that, the Arrhenius kinetic and thermodynamic Eyring-Polanyi parameters calculated from the initiation, composite, and decomposition rate constants are compared in order to assess oxidative stabilities. Finally, shelf-life predictions based on a number of proposed end-points of peroxidation are addressed.

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Effect of hydroxytyrosol (HT) and tert-butylhydroquinone (TBHQ) on the kinetics of lipid hydroperoxides (LOOH) accumulation during the initiation and propagation peroxidations of canola and fish oils at 60 °C was studied. The initiation kinetics of the inhibited peroxidation indicated considerable relative activities, A, for HT and TBHQ in the canola (> 3200 and > 27,000, respectively) and fish (> 120 and > 5000, respectively) oils. The critical concentrations of LOOH reverse micelles (CMCL = 33 mM and 57 mM in the canola and fish, respectively, oils) significantly decreased, on average, to about one-third and 8% of the initial values for HT and TBHQ, respectively. Interestingly, the propagation kinetics of the inhibited peroxidation demonstrated that the antioxidants were still able to inhibit peroxidation, so that the relative propagation oxidizability parameter Rn' was significantly improved to < 0.5 for HT and to < 0.2 for TBHQ in the canola and fish, respectively, oils.

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This study aimed to comparatively investigate the temperature effect on the kinetic parameters and rate constants representing lipid hydroperoxides (LOOH) formation and decomposition during initiation and propagation peroxidations. The initiation phase was characterized by induction period IP, overall initiation rate constant kIP, initiation oxidizability Oi, and the critical reverse micelle concentration of LOOH, CMCL. The propagation phase was characterized by its duration tp, the maximum rate of LOOH accumulation Rmax, maximum LOOH concentration [LOOH]max, propagation oxidizability Rn, composite rate constant kc, and LOOH decomposition rate constant kd. Oi and Rn indicated relatively high dependencies on temperature, respectively. Among the rate constants, kd better highlighted oxidizabilities as affected by temperature. The oxidizabilities had good correspondences with the Arrhenius kinetic (A and Ea) and Eyring thermodynamic (ΔS++ and ΔH++) parameters. The most endergonic reactions (ΔG++>0) were LOOH decompositions, followed by LOOH formations during the propagation and initiation phases, respectively.

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The antioxidant activity of gentisic (GA) and α-resorcylic (α-RA) acids was investigated by considering their molecular structures in various oxidative environments, including DPPH· scavenging assay, stripped olive and soybean oils, and the corresponding oil-in-water emulsions. The mechanism of action in the oils was evaluated in the presence of different concentrations of the antioxidants at 60 °C, using the kinetic parameters the stabilization factor (F), the oxidation rate ratio (ORR), the activity (A), and the average rate of antioxidant consumption ([Formula: see text]). GA was significantly more potent antioxidant than α-RA in all the environments. Although the less polar α-RA showed better activity in the emulsions rather than in the bulk oils, GA with an ortho-hydroxy structure had higher capacity to scavenge DPPH·, and LOO· in the oils and emulsions. The lower performance of α-RA was attributed to its participation in side reactions of chain initiation (AH + LOOH → A· + L· + H2O) and propagation (A· + LH → AH + L·) as competed with the main chain termination reaction (LOO· + AH → LOOH + A·).

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Purslane (Portulaca oleracea L.) contains a variety of natural products with different biological properties. The objective of this research was to estimate changes in total phenolics, flavonoids, and fatty acids (α-linolenic acid and linoleic acid) contents as well as antioxidant activity of P. oleracea at different growth stages. Seeds were germinated in soil-filled plastic pots at greenhouse. Leaves and stems were collected at the vegetative and flowering stages. Total phenol and flavonoid contents of the samples were determined by Folin-Ciocalteau and aluminum chloride methods, respectively. The contents of α-linolenic and linoleic acids were determined using gas chromatography analysis after transesterification of fatty acids. Furthermore, Ferric reducing antioxidant power and 1,1-diphenyl-2-picrylhydrazyl assays were used to determine the antioxidant activities. The highest contents of total phenols (698.6 mg GAE 100 g-1 DW), flavonoids (46.9 mg QE 100 g-1 DW), α-linolenic acid (2.7 mg g-1 DW) and linoleic acid (0.8 mg g-1 DW) were determined in the leaves at flowering stage. Free radical scavenging capacity was significantly affected (P ≤ 0.05) by age; and the leaves of purslane had more antioxidant potential compared to stems. A positive correlation was observed between the antioxidant activities and total phenols content. Overall, purslane leaves at flowering stage can be regarded as a valuable source of fatty acids (especially α-linolenic acid) and antioxidants in human diet.

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From an interfacial phenomena standpoint, gallic acid (GA), methyl gallate (MG), and their combination alone and together with lecithin (L) were evaluated for their inhibition against the formation of lipid hydroperoxides and carbonyl compounds in a stripped sunflower oil. Lecithin at a level (500 ppm) lower than its critical micelle concentration was able to protect the lipid system to some extent. GA (log P = -0.21), which was of higher capacity than MG (log P = - 0.14) in donating H/e- (IC50 = 36.4 vs. 39.9 µM and FRAP value = 598 vs. 514 µmol/L, respectively), exerted an antioxidant activity significantly better than MG in the bulk phase oil. Due to the improved interfacial performance, the inhibitory effect of the antioxidants was remarkably promoted in the presence of lecithin (L/GA/MG > L/GA > L/MG).

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Evaluation of oxidizing lipid systems in terms of the kinetics governing both initiation and propagation phases will provide more comprehensive and reliable information than those based on the single-parameter analyses used frequently. The aim of this study was to promote the ordinarily used evaluation methods by using many kinetic parameters and rate constants representing the two phases. To do this, a variety of triacylglycerols of various fatty acid compositions were peroxidized over time at 60 °C and the kinetic curves of lipid hydroperoxides (LOOH) accumulation were drawn. The unifying parameters representative for the initiation (Oi = 0.23-181.41 mM-1 h2) and propagation (Rn = 0.0732-0.2847 h-1) oxidizabilities were interestingly able to differentiate the oils of even relatively similar compositions. Despite the more remarkable impact of saturation on Oi, polyunsaturation indicated a higher contribution to Rn. The critical concentration of LOOH reverse micelles showed significantly different values (10.0-41.6 mM) as a function of the saturation (9.7-29.8%), monounsaturation (22.5-70.4%), and polyunsaturation (11.0-64.3%) degrees. Such a terminology will provide researchers with lots of valuable kinetic information regarding oxidizability as a function of any intrinsic and/or extrinsic factor.

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The applicability of ohmic heating, as a volumetric heating technique, has been explored in various sectors of the food industry. The use of ohmic heating for essential oil extraction is among its emerging applications. This chapter overviews the recent progress in this area of research, discusses the mechanisms involved in ohmic-based essential oil extraction processes, explains the effective process parameters, highlights their benefits, and explains the considerations to address the obstacles to industrial implementation. Ohmic-assisted hydrodistillation (OAHD) and ohmic-accelerated steam distillation (OASD) systems were proposed as alternatives to conventional hydrodistillation and steam distillation, respectively. These techniques have successfully extracted essential oils from several aromatic plants (e.g., thyme, peppermint, citronella, and lavender). Both OAHD and OASD possess a number of benefits, such as reducing the extraction time and energy consumption, compared to classical extraction methods. However, these techniques are in their infancy and further economic and upscaling studies are required for their industrial adaptation.

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Antioxidant activity of the natural flavonoids luteolin and catechin, which shows inconsistent comparative results in literature, was extensively evaluated as affected by the 1,4-pyrone moiety and 3-OH group. Catechin and luteolin were compared to the synthetic antioxidant-butylated hydroxytoluene for their 2,2-diphenyl-1-picrylhydrazyl (DPPH● ) scavenging activity in polar protic and aprotic solvents and ferric reducing-antioxidant power (FRAP). Moreover, their effect on lipid oxidation kinetics of canola and olive oil triacylglycerols as well as their oil-in-water (O/W) emulsions, in addition to oil stability indices (OSIs), was evaluated. In the DPPH● assay, catechin's 3-OH group led to lower IC50 values than luteolin's 1,4-pyrone moiety in acetone (3.4 µM compared with 9.4 µM), while there was no significant difference in methanol (IC50 = approximately 18.3 µM) or tetrahydrofuran (IC50 = approximately 27.2 µM). The FRAP test indicated a higher reducing power for catechin than for luteolin (689.4 µM compared with 573.1 µM). The antioxidants showed various performances in the oil triacylglycerols and their O/W emulsions due predominantly to the interfacial phenomena. A better OSI was found for catechin than for luteolin (20.0 to 52.7 hr compared with 3.5 to 4.2 hr) in Rancimat test.

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Anthocyanins as one of the main natural groups of food colorants undergo quick color fading, which can be diminished through protein association. The stabilization of cyanidin-3-glucoside (CYG) through binding to bovine serum albumin (BSA) was investigated at pH 3.0 using atomic force microscopy and differential scanning calorimetry along with UV-Vis absorption, steady-state fluorescence, circular dichroism, and three-dimensional emission spectral analyses merged with the multivariate curve resolution-alternative least square method. The stabilized CYG molecules were found at the site II of BSA with combined static and dynamic quenching mechanisms. Approximately 93% of the BSA binding sites were occupied in the BSA-CYG complex through hydrogen bonds and van der Waals forces with the binding constant and stoichiometry ratio of 1.88 × 105 M-1 and 1:13, respectively. The results also revealed that CYG molecules caused partial unfolding of the BSA structure, while it was not enough for significant alteration of denaturation temperature. The binding results also indicated that the reduction of H2O2-induced-CYG oxidation rate (34.78%) at pH 3.0 was mainly driven via the BSA-hemiketal association, although the colored species of CYG had a greater affinity towards BSA in the equilibrated system at pHs 1.0 and 5.0.

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Kinetic analysis of gallic acid and methyl gallate in purified Kilka oil was studied in the concentration, range 200-1600 ppm, during autooxidation in Rancimat test at 60°C. The stabilization factor (F), the oxidation rate ratio (ORR), the activity (A), and the mean rate of antioxidant consumption (Winh) were determined. The scavenging activity of 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals decreased in the order gallic acid > methyl gallate > α-tocopherol > BHT as observed in Kilka oil. There were no significant differences between the effectiveness and strength and activity of gallic acid and methyl gallate at concentrations 200, 400, and 800 ppm. However, above 800 ppm, the activity of methyl gallate became higher than gallic acid, because methyl gallate despite gallic acid did not participate in any chain propagation reactions.

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In this study, lycopene, was loaded on nanostructured lipid carrier and solid lipid nanoparticles using combination of high shear homogenization and ultrasonication method. Effect of applied lipids types, nanocarrier's type and lycopene loading on physicochemical properties of developed nanocarriers were studied. Particle sizes of developed nanocarriers were between 74.93 and 183.40 nm. Encapsulation efficiency of nanostructured lipid carrier was significantly higher than solid lipid nanoparticles. Morphological study of developed nanocarriers using scanning electron microscopy showed spherical nanoparticles with smooth surface. Lycopene was entrapped in nanocarriers without any chemical interaction with coating material according to Fourier transform infrared spectroscopy spectrum and differential scanning calorimetry thermogram. Glycerol monostearate containing nanoparticles showed phase separation after 30 days in 6 and 25 °C, whereas this event was not observed in nanosuspensions that produced by glycerol distearate. Lycopene release in gastrointestinal condition was studied by the dialysis bag method. To evaluate nanocarrier's potential for food fortification, developed lycopene-loaded nanocarriers were added to orange drink. Results of sensory analysis indicated that nanoencapsulation could obviate the poor solubility and tomato after taste of lycopene. Fortified sample with lycopene nanocarriers didn't show significant difference with blank orange drink sample except in orange odor.

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Native acorn starch had high purity and the granules were mainly elliptical and spherical with the mean diameter of 7.32 µm. Hydrothermal modifications slightly changed the morphology. The solubility, swelling properties and amylose leaching of acorn starch were mostly influenced by Heat-moisture treatment (HMT). XRD pattern of native starch (C-type) did not change on hydrothermal modifications, but native and annealing (ANN) modified starches showed the most crystallinity. DSC results showed that the gelatinization temperatures and enthalpy of native starch were 59.9, 71.3, and 80.6 °C and -14.9 mJ/mg, respectively, and hydrothermal treatments generally increased the gelatinization temperatures. Regarding to RVA results, peak, breakdown, trough, setback, and final viscosities of native starch were 415, 143, 272, 168, and 440 RVU, respectively, and viscosity parameters of native starch were mainly more than those of hydrothermally modified starches. Generally, the intensity of the effects of hydrothermal modifications followed the order: HMT > dual modifications > ANN.

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