High‐Purity Tocored Improves the Stability of Stripped Corn Oil Under Accelerated Conditions

γ‐Tocopherol‐5,6‐quinone (tocored) is of importance among the γ‐tocopherol (γ‐T) oxidant products and found in corn germ oil. Investigation on tocored is impeded in part by the difficulty to access high purity tocored. In this present study, high‐purity tocored is successfully prepared, and its antioxidant activity, together with γ‐T and TBHQ (positive control) in increasing concentrations in stripped corn germ oil is evaluated by Rancimat and Schaal oven tests. The stabilization factor in the Rancimat tests increases significantly (p < 0.05) along with an increase in the levels of antioxidants. Furthermore, tocored exhibits higher stabilization than γ‐T in the Schaal oven tests, although its efficacy gradually increases up to 100 mg kg^–1 and decreases significantly at higher levels (from 100 to 500 mg kg^–1), drawn from the comprehensive parameter A (considering both efficiency and strength) changes (5.06–11.21). In addition, the curves illustrating the residual contents of tocored and γ‐T run in different ways when the four levels are taken into consideration, further bearing the above results. Tocored tends to be a potent natural antioxidant for edible corn germ oil preservation. Practical Application: The present work provides more clear procedures for high‐purity tocored synthesis. Furthermore, tocored may be a potential natural antioxidant that is especially suitable for lipid base food substrates. The results of the present work contribute to the deeper understanding of the antioxidant activity of γ‐tocopherol. The antioxidant activity of tocored is higher than γ‐tocopherol in Schaal oven test. Tocored is a bright orange‐red substance that affects the appearance of the edible oil. Meanwhile, γ‐tocopherol is well known for its valuable health benefits, and appropriate measures should be adopted to store oils (corn oil, soybean oil, and so on) rich in γ‐tocopherol to control transformation in order to keep stability optimal. To some degree, the practical applications of the present results are also related to the processing and storage of edible oils.     

Determination of polyphenols,tocopherols, and antioxidant capacity in virgin argan oil (Argania spinosa,Skeels)

This study establishes data on polyphenols, tocopherols, and antioxidant capacity (AC) of virgin argan oil. A total of 22 samples from Morocco were analyzed. Total polyphenol content ranged between 6.07 and 152.04 mg GAE/kg. Total tocopherols varied between 427.0 and 654.0 mg/kg, being γ‐tocopherol the major fraction (84.68%); α‐, β‐, and δ‐tocopherols represent 7.75, 0.33, and 7.29%, respectively. No influence of oil extraction method on total tocopherols was observed. The AC of argan virgin oils determined by the ABTS method in n‐hexane oils dilution ranged between 14.16 and 28.02 mmol Trolox/kg, and by the ABTS, DPPH, and FRAP methods in methanolic oil extracts between 2.31–14.15, 0.19–0.87, and 0.62–2.32 mmol Trolox/kg, respectively. A high correlation was found between ABTS and DPPH methods applied to a methanolic oil extract. Virgin argan oil presents a higher polyphenol and tocopherol content, and total AC than other edible vegetable oils.     

Iron‐Catalyzed Reaction of γ‐Tocopherol with Methyl Linoleate Hydroperoxides in Solutions

γ‐Tocopherol is one of the main constituents in vegetable oils and acts as an antioxidant by trapping lipid‐peroxyl radicals. This study reports reaction products of γ‐tocopherol with lipid‐peroxyl radicals formed by iron‐catalyzed decomposition of methyl linoleate hydroperoxides (MeLOOH) in toluene and methanol solutions. The products in toluene solution were tocored, methyl (8a‐dioxy‐γ‐tocopherone)‐epoxyoctadecenoates (γT‐OO‐epoxyMeL), methyl (8a‐dioxy‐γ‐tocopherone)‐octadecadienoates (γT‐OO‐MeL), γ‐tocopherol biphenyl dimer (γTBD), γ‐tocopherol diphenylether dimer (γTED), and adducts of γ‐tocopherol dimers with the MeLOOH‐derived peroxyl radicals (γTED‐OO‐epoxyMeL, γTBD‐OO‐MeL, and γTED‐OO‐MeL). The iron‐catalyzed reaction in toluene proceeded slowly, whereas the reaction in methanol was relatively fast. The reaction products in methanol were γT‐OO‐epoxyMeL and γTED‐OO‐epoxyMeL together with tocored, γTBD, and γTED. The results indicate that the iron‐catalyzed decomposition of MeLOOH in toluene produces both epoxyperoxyl and peroxyl radicals and that the decomposition in methanol yields only the epoxyperoxyl radicals. These peroxyl radicals could react with the 8a‐carbon‐centered radical of γ‐tocopherol or its dimers.     

Lipid characterization and antioxidant status of the seeds and meals of Camelina sativa and flax

Four different antioxidant activity assays including 2,2′‐azino‐bis(3‐ethylbenzothiazoline‐6‐sulfonic acid (ABTS), 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH), ferric reducing antioxidant power (FRAP) and oxygen radical absorption capacity (ORAC), and thiobarbituric acid reactive substances were performed on the methanolic and ethyl acetate extracts of Camelina seeds (CS), flaxseeds (FS), Camelina meal low fat (CMLF, 9.9% fat), Camelina meal high fat (CMHF, 24.6% fat), and flaxseed meal (FSM, 2.7% fat). In addition, the fatty acid profile, and phenolic, tocopherol, flavonoid, and glucosinolate contents of CS, FS, CMLF, CMHF, and FSM were studied. The major fatty acid was α‐linolenic acid (C18:3 n‐3) which was 33.2, 29.4, 30.2, 60.1, and 39.3% in CS, CMLF, CMHF, FS, and FSM, respectively. The methanolic extract of CMLF showed the highest values of ABTS, DPPH and FRAP and the highest content of phenolic compounds, flavonoids, and glucosinolates. The methanolic and ethylacetate extracts of CMHF showed the highest values for ORAC and α‐ and γ‐tocopherols. The ethylacetate extracts of seeds and meals of Camelina sativa and flax showed lower values for antioxidant activity, phenolic compounds, and flavonoids than the methanolic extracts. In general, Camelina and FS meals showed higher antioxidant activities, and phenolic and flavonoid contents than their respective seeds. Practical applications: Camelina sativa seeds (CS) and flaxseeds (FS) are rich sources of omega 3 oils. Their by‐products after oil extraction are an attractive source of proteins, lipids, fiber, and natural bioactive compounds such as antioxidants. These by‐products may be used to improve nutritional value and prevent lipid oxidation in feed or food systems.     

Evaluation of the Antioxidant Properties of Micronutrients in Different Vegetable Oils

Micronutrients (tocols, sterols, and total phenolic) and antioxidant activities of 15 varieties of common vegetable oil samples obtained from different countries are investigated. All methanol extracts are assayed for total antioxidant ability and cellular antioxidant activity (CAA) using oxygen radical absorbance capacity (ORAC) method and CAA assay. CAA has been widely used in the evaluation of food antioxidants recently. It quantifies antioxidant capacity utilizing a HepG2 cell model, which is more biologically representative. Linseed and sesame oils show much higher CAA values than the others tested; however, levels of walnut, sunflower, and coconut oils are extremely low, which are hard to be quantified. A significant correlation between the ORAC and CAA values and total phenolic content (p < 0.05) is observed. High‐phenolic olive oil has the highest level of phenolics and the highest ORAC, while linseed oil has the highest CAA value. Based on this, choosing proper edible oil consumption may reduce oxidative damage of human body and promote the precision processing of edible oil such as retaining beneficial ingredients moderately. Practical Application: This study demonstrates the evaluation of the universality of vegetable oils by the cellular antioxidant model and provides a data reference for the selection of edible oils with excellent antioxidant properties.     

Mulberry Seed Oil: a Rich Source of δ‐Tocopherol

In the present study, mulberry seed oil (MSO) samples obtained from seeds of different mulberry varieties as well as concentrated mulberry juice production waste (mulberry pomace) were investigated. Radical scavenging capacity, tocopherol and total phenolic content of MSO were determined. It was observed that MSO contain unique amounts of δ‐tocopherol varying between 1645–2587 mg kg^?1 oil depending on the variety. The secondary tocopherol homologue was γ‐tocopherol within a concentration range of 299–854 mg kg^?1 oil. MSO exhibited a very high antioxidant capacity varying in the range of 1013–1743 and 2574–4522 mg α‐tocopherol equivalents (α‐TE) per kg of oil for 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) and freeze‐dried 2,2′‐azino‐bis (3‐ethylbenzothiazoline‐6‐sulfonic acid) (FD‐ABTS) radical cation assays, respectively. Both antioxidant capacity and total phenolic content were higher for mulberry pomace oil compared with the seed oils. Fatty acid composition of MSO was also determined, and linoleic acid was found to be the primary fatty acid (66–80 %).     

On‐line LC‐NMR‐MS characterization of sesame oil extracts and assessment of their antioxidant activity

Sesame lignans were isolated by solvent extraction and subsequently purified by solvent crystallization from crude, unroasted sesame oil, and a sesame oil deodorizer distillate. In addition, an aliquot of the purified sesame oil extract was treated with camphorsulfonic acid to obtain a sesaminol‐enriched extract. The sesame lignan composition of the extracts was characterized by on‐line liquid chromatography nuclear magnetic resonance spectroscopy mass spectrometry coupling (LC‐NMR‐MS). The effect of the sesame oil extracts as well as pure sesame lignans and γ‐tocopherol on the oxidative stability of sunflower oil (lignan‐free) was studied by the Rancimat assay. The Rancimat assay revealed the following oxidative stability order: sesame oil extract < sesame oil deodorizer distillate < sunflower oil (no added sesame oil extracts) < sesamol < sesaminol‐enriched sesame oil extract. In addition, the radical‐scavenging capacity of these extracts was assessed by the Trolox® equivalent antioxidant capacity (TEAC) assay. The TEAC assay revealed a slightly different AOX activity order: sesamin < sesame oil extract < sesaminol‐enriched sesame oil extract < sesamol. In conclusion, the sesaminol‐enriched extract revealed strong antioxidant activity and is therefore suitable to increase the oxidative stability of edible oils high in polyunsaturated fatty acids.     

Quality Changes and Antioxidant Properties of Microencapsulated Kenaf (Hibiscus cannabinus L.) Seed Oil During Accelerated Storage

Quality changes and antioxidant properties of microencapsulated kenaf (Hibiscus cannabinus L.) seed oil (MKSO) were investigated at 6-day intervals during 24 days of storage at 65 °C. DPPH, ABTS, FRAP and BCB assays were used to determine the antioxidant activity (AOA) and their correlations were reported. Total flavonoids content (TFC) and oxidative stability in terms of evolution of thiobarbituric acid reactive substances (TBARS) were also studied. The results showed that there was a significant (p < 0.05) effect of microencapsulation whereby AOA of MKSO showed only a 23.28 % decrease as compared to a 61.51 % decrease in the control bulk oil (KSO) when assessed by FRAP. MKSO showed significantly (p < 0.05) lower reduction of its initial TFC as compared to KSO and total increase in TBARS of MKSO was reported to be significantly (p < 0.05) lower than that of KSO. AOA determined by all assays were well correlated with TFC and also among themselves. Microencapsulation of kenaf seed oil was found to be effective in the stabilisation of natural antioxidants and prolonging the shelf-life.     

Effects of tocopherols and their mixtures on the oxidative stability of olive oil and linseed oil under heating

The tested tocopherols (γ,δ,α) showed antioxidative activity at all levels of addition to the monounsaturated olive oil, the effects increased as a function of concentrations (maximum: +287% with 800 mg γ‐tocopherol/100 g oil compared to the control oil). In the highly unsaturated linseed oil, which contains 58 mg/100 g initial concentration of γ‐tocopherol, γ‐tocopherol showed antioxidative behavior up to the addition of 100 mg/ 100 g oil. Additions of more than the 100 mg/100 g affected the oil, resulting in a faster oxidation. Mixtures of γ/δ‐tocopherols in olive oil were found to protect more efficiently than both vitamins when added separately α‐tocopherol reduced effects of other tocopherols in both plant oils. The stabilizing effect of added tocopherols and their mixtures (100 mg/100 g oil each) in olive oil are γ/δ‐T>γ‐T>δ‐T>γ/α‐T>δ/α‐T>α‐T and in linseed oil γ‐T>γ/δ‐T>δ‐T>γ/α‐T>α‐T>α/δ‐T.     

Effects of tocopherols and tocotrienols on the inhibition of autoxidation of conjugated linoleic acid

The effect of eight vitamin E homologues, i.e. α‐, β‐, γ‐, and δ‐tocopherol and α‐, β‐, γ, and δ‐tocotrienol, on the inhibition of autoxidation of conjugated linoleic acid (CLA) were investigated. The oxidation was carried out in the dark for 21 days at 50 °C and monitored by peroxide values (PV) and TBA values. The levels of the individual vitamin E homologues in CLA during storage were determined by HPLC. γ‐Tocopherol exhibited the highest antioxidant activity among the homologues tested in this study when the antioxidant activities of the individual homologues in CLA were compared by PV. The order of antioxidant activity of eight homologues was γ‐tocopherol > δ‐tocopherol = δ‐tocotrienol ≥ γ‐tocotrienol > β‐tocopherol = β‐tocotrienol > α‐tocopherol = α‐tocotrienol. The degradation rates of α‐tocopherol and α‐tocotrienol were faster than those of the other homologues, whereas δ‐tocopherol had the highest stability in CLA during storage. All homologues exhibited an antioxidant activity by inhibiting the formation of secondary oxidation products. It appears that α‐tocotrienol and β‐tocotrienol have significantly higher antioxidant activities for secondary oxidation in CLA than α‐tocopherol and β‐tocopherol. Meanwhile, the other homologues, namely γ‐tocopherol, γ‐tocotrienol, δ‐tocopherol, and δ‐tocotrienol, exhibited similar antioxidant activity for secondary oxidation in CLA.     

Physicochemical Properties,Chemical Composition and Antioxidant Activity of <Emphasis Type="Italic">Dalbergia odorifera</Emphasis> T. Chen Seed Oil

The heartwood or root of Dalbergia odorifera T. Chen is an important traditional medicine in Asia. The aim of the present study was to evaluate the physicochemical properties, chemical composition and antioxidant activity of Dalbergia odorifera T. Chen seed oil. Oil, protein, carbohydrate, moisture, ash and total phenolic contents were found to be 12.96, 26.86, 42.58, 13.70, 3.90 and 5.55%, respectively. Free fatty acids, iodine number, peroxide value, saponification number and unsaponifiable matter were 1.66%, 106.53 g/100 g, 5.07 meq O₂/Kg, 196.78 mg KOH/g and 1.70%, respectively. The oil showed high absorbance in the UV-B and UV-C ranges with potential for use as a broad spectrum UV protectant. The major fatty acids were linoleic acid (60.03%), oleic acid (17.48%) and palmitic acid (16.72%). The total tocopherol, total phenolics and β-carotene were 511.9, 351.1 and 62.2 mg/kg oil, respectively. In addition, the methanol extract of seed oil showed significant in vitro antioxidant activity in four assays including DPPH radical scavenging activity, reducing power, linoleic acid peroxidation inhibition and chelating activity. This study suggests that Dalbergia odorifera T. Chen seed oil has the potential to be used in new products in the functional food, cosmetic or pharmaceutical industries.     

A polyphenol extract of tara pods (Caesalpinia spinosa) as a potential antioxidant in oils

Tara is a native species of Peru and is widely distributed in Latin America; its fruits (pods) have a high potential for medical, industrial and food uses. A supercritical tara polyphenol extract (STPE) was obtained from tara pods by supercritical fluid extraction (SFE) with CO₂. The antioxidant activity of the STPE was studied in two oils, regular and high‐oleic sunflower oil (SO, HOSO), with and without their natural antioxidants. Under accelerated conditions of oxidation, a linear relationship was observed in antioxidant‐stripped oils between the polyphenol content of the STPE and the induction period. The antioxidant effect of STPE on the HOSO was studied at 60°C. The highest polyphenol concentration of STPE showed the greatest α‐tocopherol degradation and the lowest hydroperoxide formation, which implies that α‐tocopherol causes the regeneration of the polyphenols that protect the TAGs in HOSO. Tara pods combined with SFE method could be used as a source of antioxidants in oils.     

Evaluation of natural and synthetic compounds according to their antioxidant activity using a multivariate approach

The antioxidant activity of natural and synthetic compounds was evaluated using five in vitro methods: ferric reducing/antioxidant power (FRAP), 2,2‐diphenyl‐1‐picrylhydradzyl (DPPH), oxygen radical absorption capacity (ORAC), oxidation of an aqueous dispersion of linoleic acid accelerated by azo‐initiators (LAOX), and oxidation of a meat homogenate submitted to a thermal treatment (TBARS). All results were expressed as Trolox equivalents. The application of multivariate statistical techniques suggested that the phenolic compounds (caffeic acid, carnosic acid, genistein and resveratrol), beyond their high antioxidant activity measured by the DPPH, FRAP and TBARS methods, showed the highest ability to react with the radicals in the ORAC methodology, compared to the other compounds evaluated in this study (ascorbic acid, erythorbate, tocopherol, BHT, Trolox, tryptophan, citric acid, EDTA, glutathione, lecithin, methionine and tyrosine). This property was significantly correlated with the number of phenolic rings and catecholic structure present in the molecule. Based on a multivariate analysis, it is possible to select compounds from different clusters and explore their antioxidant activity interactions in food products.     

In vitro antioxidant and in vivo antidiabetic,antihyperlipidemic activity of linseed oil against streptozotocin‐induced toxicity in albino rats

The intake of omega‐3 unsaturated fatty acids has a beneficial effect on insulin sensitivity in rats and in subjects with type 2 diabetes. It has been reported that these omega‐3 fatty acids are useful in the treatment of hypertriglyceridemia and in the enhancement of high‐density lipoprotein (HDL)‐cholesterol levels in diabetic patients. The present study was therefore aimed to evaluate the antioxidant, antihyperglycemic and antihyperlipidemic effect of L. usitatissimum fixed oil. The antioxidant activity was evaluated in vitro using 1,1‐diphenyl‐2‐picryl hydrazyl (DPPH) and hydrogen peroxide (H₂O₂) assay. The oil exhibited significant in vitro antioxidant activity in the DPPH and H₂O₂ assay. The oil (1, 2, 3 mL/kg) was further investigated against streptozotocin (STZ)‐induced hyperglycemia and hyperlipidemia in albino rats, subjected to 3 weeks of treatment. The oil manifested decrease in blood glucose and glycated hemoglobin levels at higher dose and significant dose dependent negating action on antioxidant enzymes in the heart, liver and kidney tissues. The oil also normalized the various hematological parameters and electrolyte levels in the STZ treated rats. Treatment with oil significantly increased the level of serum HDL and decreased the levels of total cholesterol, triglycerides, and low‐density lipoprotein‐cholesterol in STZ‐diabetic rats in comparison to normal control. The antioxidant, antihyperglycemic and antihyperlipidemic activity of the oil could be attributed to the presence of linolenic acid (ALA, 18:3 n‐3) and its metabolic products, eicosapentanoic acid (EPA, 20:5 n‐3) and docosahexanoic acid (DHA, 22:6 n‐3).     

Chemical Composition and Antioxidant Activity of Seeds of Various Halophytic Grasses

Increasing population has resulted in overexploitation of conventional seeds. The limited supply of water and salinization of agricultural lands are threats to crop production. This creates food insecurity and results in ever‐increasing prices of crops and edible oils. Halophytes that produce high‐quality seeds can serve as sources of oil and edible products. We analyzed the chemical composition and antioxidant activity of seeds from 5 halophytic grasses, i.e., Aeluropus lagopoides, Eragrostis ciliaris, Eragrostis pilosa, Panicum antidotale, and Sporobolus ioclados. These seeds contained crude protein (10–29%), carbohydrates (32–55%), crude fiber (4–21%), minerals (3.8–9.2%), and oil (4–11%), indicating their nutritional potential. Oils of these seeds had suitable fatty‐acid composition with 62–82% unsaturation and only 17–24% saturation. Out of this, 91–94% of the total oil constituted by linoleic, oleic, and palmitic acids. High contents of total phenols (2.8–4.2 mg gallic acid equivalent [GAE] g^?1), flavonoids (0.5–1.3 mg Quercetin equivalent [QE] g^?1), and tannins (0.3–1.3 mg catechin equivalent [CE] g^?1) supported their high antioxidant activity (1,1‐Diphenyl‐2‐picryl‐hydrazyl (DPPH) activity in terms of half maximal inhibitory concentration‐IC₅₀ 1.1–5.86 mg mL^?1; 2,2′‐azino‐bis3‐ethylbenzothiazoline‐6‐sulphonic acid (ABTS) 18.8–72.8 mmol Trolox g^?1; ferric‐reducing antioxidant power 2.0–4.4 mmol Fe⁺² g^?1). The reverse phase‐high‐pressure liquid chromatography analysis identified the presence of bioactive phenolic antioxidants (mainly gallic acid, chlorogenic acid, coumaric acid, ferulic acid, kaempferol, and quercetin). Due to these characteristic composition and salt tolerability, these plants can serve as potential sources of industrial raw materials for food, edible oil, phytochemicals, and oliochemicals.     

3, 4‐Dihydroxymandelic acid amides of alkylamines as antioxidants for lipids

The antioxidative and radical scavenging activity of the 3, 4‐dihydroxymandelic acid (DHMA) amides of hexylamine, 2‐ethylhexylamine, octylamine, and cyclohexylamine was determined by several physicochemical test systems. The amides were synthesized by protecting group‐free coupling of in situ prepared N‐hydroxysuccinimidylester of DHMA and the amines. The radical scavenging activity was determined using the DPPH (2, 2‐diphenyl‐1‐picrylhydrazyl) method and by quenching superoxide anions generated using a horse radish peroxidase/H₂O₂ system. In the DPPH assay, all amides show higher radical scavenging activity (EC₅₀ 0.09‐0.12 mol/mol_DPPH) compared to the standard antioxidants ascorbic acid (EC₅₀ 0.27 mol/mol_DPPH) and tocopherol (EC₅₀ 0.25 mol/mol_DPPH). The amides are also more potent superoxide radical scavengers (IC₅₀ < 600 nm) than standard ascorbic acid (IC₅₀ 700 nm). Activity against lipid peroxidation was determined by accelerated autoxidation of highly unsaturated oils and squalene using the Rancimat. Again, the antioxidative potentials of the DHMA amides against lipid oxidation as determined by the Rancimat, are at least equal or higher compared to the standard lipid antioxidants tocopherol, BHT, BHA, and ascorbylpalmitate (concentration in soybean oil 0.05%, all other oils 0.025%, squalene 0.005%). In squalene, an equi‐amount mixture of DHMA octylamide and α‐tocopherol shows a synergistic effect. Last but not least, the amides are able to protect an emulsion of linoleic acid/β‐carotene against oxidation initiated by N, N‐azodiisobutyramidine dihydrochloride (IC₅₀ 0.19‐0.77 mmol/l, ascorbic acid > 0.9, tocopherol 0.08). The DHMA octylamide in combination with ascorbic acid shows a synergistic antioxidative effect in the emulsion model. In conclusion, the new alkylamides of DHMA are easy to synthesize, potent radical scavengers and protect lipids, in particular the highly unsaturated, both in bulk and in emulsions against autoxidation.     

Kinetics of antioxidant action of α‐ and γ‐toco‐pherols in sunflower and soybean triacylglycerols

A kinetic analysis was performed to evaluate the antioxidant behavior of α‐ and γ‐to‐copherols (5—2000 ppm) in purified triacylglycerols obtained from sunflower oil (TGSO) and soybean oil (TGSBO) at 100 °C. Different kinetic parameters were determined, viz. the stabilization factor as a measure of effectiveness, the oxidation rate ratio as a measure of strength, and the antioxidant activity which combines the other two parameters. In the low concentration range (up to 400 ppm in TGSBO and up to 700 ppm in TGSO) α‐tocopherol was a more active antioxidant than γ‐tocopherol whereas the latter was more active at higher concentrations. It has been found that the different activity of the tocopherols is not due to their participation in chain initiation reactions, but that the loss of antioxidant activity at high tocopherol concentrations is due to their consumption in side reactions. The rates of these reactions are higher in TGSBO than in TGSO. Both α‐tocopherol itself and its radicals participated more readily in side reactions than γ‐tocopherol and its radicals. Both α‐ and γ‐tocopherol reduce lipid hydroperoxides, thus generating alkoxyl radicals which are able to amplify the rate of lipid oxidation by participating in chain propagation reactions.     

Thermally crosslinked anionic hydrogels composed of poly(vinyl alcohol) and poly(γ‐glutamic acid): Preparation,characterization, and drug permeation behavior

pH‐sensitive anionic hydrogels composed of poly(vinyl alcohol) (PVA) and poly(γ‐glutamic acid) (γ‐PGA) were prepared by the freeze drying method and thermally crosslinked to suppress hydrogel deformation in water. The physical properties, swelling, and drug‐diffusion behaviors were characterized for the hydrogels. In the equilibrium swelling study, PVA/γ‐PGA hydrogels shrunk in pH regions below the pK_a (2.27) of γ‐PGA, whereas they swelled above the pK_a. In the drug‐diffusion study, the drug permeation rates of the PVA/γ‐PGA hydrogels were directly proportional to their swelling behaviors. The cytocompatibility test showed no cytotoxicity of the PVA/γ‐PGA hydrogels for the 3T3 fibroblast cell lines. The results of these studies suggest that hydrogels prepared from PVA and γ‐PGA could be used as orally administrable drug‐delivery systems. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Influence of Different Moisture Contents on the Stability of Tocochromanols in Bulk Oils at 25 °C Storage

The stabilities of tocochromanols including α‐tocopherol, α‐tocotrienol, γ‐tocopherol, γ‐tocotrienol, and δ‐tocotrienol in grape seed oil, palm oil, or stripped soybean oil with added tocotrienol mixtures (SOTT) were determined under relative humidity (RH) 0, 32, 75, and 93% at 25 °C for 8 months of storage. Stability of tocochromanols was significantly influenced by the presence of moisture and other tocochromanols. Tocochromanol stability in grape seed oil was high at RH 75%, whereas palm oil had significantly lower tocochromanol content at RH 75% compared to those under other RH (p < 0.05). Tocochromanol stability in SOTT was high at RH 0%. δ‐Tocotrienol had the highest stability followed by α‐tocotrienol, γ‐tocotrienol, and α‐tocopherol in SOTT. Moisture content in palm oil was the lowest while that in SOTT was the highest at the same RH. Oxidative stability of palm oil was the highest followed by grape seed oil and SOTT based on conjugated dienoic acid content and p‐anisidine values. Moisture in oils affects the stability of tocochromanols and oxidative stability in vegetable oils.