Assessment of antioxidant activity and phycocyanin release of Spirulina loaded poly(ε-caprolactone) electrospun nanofibers

PCL with biodegradable property and Spirulina with various biological activities offer good alternative ingredients for the fabrication of functional nanofibers in tissue engineering. The aim of the study is to obtain PCL/Spirulina nanofibers with low diameters and to determine their wettability, antioxidant activity, and phycocyanin release to evaluate their potential as bioactive scaffolds in different applications. PCL/acetic acid/pyridine solutions with three different Spirulina concentrations were electrospun and the obtained nanofibers were investigated. The thinnest PCL/Spirulina nanofibers (117.20 nm) were obtained at 1.5% Spirulina concentration. Although PCL nanofibers with 6% Spirulina concentration showed the highest antioxidant activity and amount of phycocyanin released, PCL nanofibers with 3% Spirulina concentration having similar in vitro results showed superiority when considering the diameter and uniformity of the nanofibers and the cost of the material. The PCL/Spirulina nanofibers with small diameters and antioxidant activity could be regarded as potential extracellular matrix material for tissue engineering.     

Preparation and characterization of α-tocopherol nanocapsules based on gum Arabic-stabilized nanoemulsions

Food Science and Biotechnology - The preparation of water dispersed α-tocopherol nanocapsules through solvent-displacement technique using gum Arabic (GA) as natural stabilizing and...     

Rheological,thermal and structural behavior of poly(ε-caprolactone) and nanoclay blended films

Poly(ε-caprolactone)/nanoclay composite (PCLNC) films were prepared by solvent casting method using a wide range of layered silicate (2.5–10%) and were characterized by different techniques. Nanofiller dispersions in PCL matrix were studied by wide-angle X-ray diffraction (XRD) and transmission electron microscopy (TEM), and results indicated the formation of some intercalated nanostructure of PCLNC. Rheological and thermal properties of PCLNC were measured by parallel-plate oscillatory rheometry and differential scanning calorimetry (DSC), respectively. Rheological study indicated that the predominating liquid-like properties (viscous modulus, G″ > elastic modulus, G′) of neat PCL gradually transformed to solid-like (G′ > G″) behavior after incorporation of clay in the temperature range of 90–120 °C. A plot of G′ vs. G″ provide information on intercalation and microstructure of nanocomposite. Applicability of time–temperature superposition (TTS) principle and van Gurp–Palmen plot (phase angle vs. absolute complex modulus) on rheological data of clay incorporated PCL were employed and found that the results failed to follow the rules. Incorporation of the nanoclay into PCL matrix increased the crystallization temperature (T_c) and melting temperature (T_m) of neat PCL from 28.7 to 32.3 °C and 56.3 to 59.2 °C, respectively due to the nucleating effect, but the glass transition temperature (T_g) (≈−65 °C) was remained unaffected. The decrease in crystallinity with increase in clay concentration was confirmed by both XRD and DSC data.     

Uptake of α-tocopherol in porcine plasma and tissues

The effect of feeding α-tocopheryl acetate to pigs on the rate and extent of uptake of α-tocopherol in various tissues was investigated. The rate of iron ascorbate-induced lipid peroxidation was also studied. One hundred and eight Landrace × Large White pigs were assigned at random to one of the following barley-based diets: 20 mg α-tocopheryl acetate/kg feed for up to 126 days; 20 mg/kg feed to day 91, followed by 200 mg/kg feed to day 126, or 200 mg/kg feed for up to 126 days: Pigs from each group were slaughtered at specified intervals. For pigs fed the diet supplemented with 200 mg α-tocopheryl acetate/kg feed, α-tocopherol levels increased with increasing supplementation time up to day 126 in all tissues studied. The highest levels of α-tocopherol were observed in kidney fat and subcutaneous fat (inner layer) followed by subcutaneous fat (outer layer), liver, lung, heart, kidney, with muscle and brain containing approximately the same level. The α-tocopherol concentrations in all tissues examined, from pigs fed 200 mg α-tocopheryl acetate/kg feed from weaning to day 126 were greater than those fed the supplemented diet for 35 days. Iron-induced lipid peroxidation was reduced by dietary α-tocopheryl acetate supplementation, and muscle samples from pigs supplemented for 126 days were significantly (p < 0.05) less susceptible to peroxidation compared to muscle from pigs fed the same supplemented diet for 35 days.     

Effect of dietary α-tocopherol supplementation and gamma-irradiation on α-tocopherol retention and lipid oxidation in cooked minced chicken

The effects of dietary α-tocopherol supplementation and gamma-irradiation on α-tocopherol retention and lipid oxidation in cooked minced chicken during refrigerated storage were studied. Minced breast and thigh meat from broilers fed diets supplemented with 100, 200 or 400 mg α-tocopheryl acetate/kg feed was irradiated at 2.5 or 4.0kGy. Cooked irradiated and unirradiated meat was stored at 4 °C for 5 days. α-Tocopherol concentrations increased with increasing dietary supplementation. Concentrations decreased during storage, but retention was not affected by irradiation. Lipid stability was determined by measuring the formation of thiobarbituric acid-reacting substances (TBARS) and cholesterol oxidation products (COPs) during storage. TBARS and COPs increased during storage and were reduced by increasing levels of dietary α-tocopheryl acetate supplementation. Irradiation accelerated TBARS formation during storage, but this was prevented by supplementation with 200 mg α-tocopheryl acetate/kg feed. Irradiation tended to increase COPs during storage, although no consistent effects were observed. In general supplementation with over 400 mg α-tocopheryl acetate/kg feed may be required to control cholesterol oxidation in minced chicken. The results suggest that, overall, irradiation had little effect on lipid stability in α-tocopherol-supplemented meat following cooking and storage.     

Effect of dietary linseed oil and α-tocopherol on pork tenderloin (Psoas major) muscle

The effect of linseed oil and α-tocopheryl acetate on the fatty acid composition and the susceptibility to oxidation of lipid fraction from pork tenderloin (Psoas major) muscle has been studied. Muscles were obtained from animals fed on diets with the same ingredients excepting the oil source [sunflower (C), linseed (L) and linseed and olive (1/1, w/w) (LO)] and α-tocopherol [20 (C, L and LO) or 200 (LOE and LE) mg/kg diet]. The n-6/n-3 ratio in pork tenderloin was markedly modified by dietary linseed oil administration, which was due to the increase in the C18:3n-3 (and total n-3 fatty acids) and the decrease in the C18:2n-6 (and total n-6 fatty acids) contents (P<0.05). The α-tocopherol content of tenderloin from batches LE and LOE was about 2.8 mg/kg of muscle, significantly greater (P<0.05) than about 0.7 mg/kg muscle found in tenderloin from pigs receiving C, L and LO. Dietary supplementation with α-tocopheryl acetate markedly reduced tenderloin lipid oxidation from animals fed diets enriched in n-3 fatty acids (L or LO vs LE or LOE).     

Rapid determination of α-tocopherol in muscle and adipose tissues of pork

A fast, sensitive and reproducible method for the analysis of -tocopherol in pork tissues is presented. It combines saponification of the tissue and -tocopherol extraction in a single vessel, followed by HPLC separation and fluorescence detection. Added -tocopherol was recovered quantitatively. The reduction of lipid peroxides with potassium iodide before the saponification step did not alter the amounts of -tocopherol detected. Membranebound -tocopherol was not oxidized by lipid peroxides during the procedure. The coefficient of variation of -tocopherol analysed using this method was ±4.2% for muscle and ±2.5% for adipose tissues.

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Methode zur schnellen Bestimmung von -Tocopherol in Muskel- und Fettgeweben des Schweines

Zusammenfassung Es wird eine schnelle, empfindliche und reproduzierbare Methode zur Bestimmung von -Tocopherol im Schweinefleisch vorgestellt. Die Methode verbindet die Verseifung des Gewebes und die Extraktion in einem Gefäß. Nach HPLC-Abtrennung wird das -Tocopherol mit einem Fluoreszenzdetektor bestimmt. Zugesetztes -Tocopherol wurde quantitativ wiedergefunden. Die Reduktion der Lipidperoxide mit Kaliumjodid vor der Verseifung hatte keinen Einfluß auf die im Gewebe bestimmten -Tocopherolgehalte. Das membrangebundene -Tocopherol wird während der Bestimmung nicht durch Lipidperoxide oxidiert. Der Variationskoeffizient der Methode lag für Muskelgewebe bei ±4,2% und für Fettgewebe bei ±2,5%.

     

Seasonal changes of α-tocopherol in green marine algae (Caulerpa genus)

Abstract: Marine algae are a promising source of beneficial compounds for human use. Among these, pro‐vitamin A carotenoids and vitamins B, C, and E stand out. The objective of this study was to investigate seasonal variation of α‐tocopherol levels in 5 species of green marine algae of the Caulerpa genus. This research was carried out with both fresh and dry specimens; and, in addition, differences arising as a result of the drying process were examined. Analyses were carried out by high‐performance liquid chromatography (HPLC) using an isocratic system and a reversed‐phase C‐18 column. The distribution of α‐tocopherol throughout the year in Caulerpa genus was variable. All samples of both fresh and dried algae contained α‐tocopherol, except for the dried C. racemosa from March 2006. The drying process was responsible for losses of α‐tocopherol ranging from 21% to 93%.     

Identification and characterization of yak α-lactalbumin and β-lactoglobulin

α-Lactalbumin (α-LA) and β-lactoglobulin (β-LG) were isolated from yak milk and identified by mass spectrometry. The variant of α-LA (L8IIC8) in yak milk had 123 amino acids, and the sequence differed from α-LA from bovine milk. The amino acid at site 71 was Asn (N) in domestic yak milk, but Asp (D) in bovine and wild yak milk sequences. Yak β-LG had 2 variants, β-LG A (P02754) and β-LG E (L8J1Z0). Both domestic yak and wild yak milk contained β-LG E, but it was absent in bovine milk. The amino acid at site 158 of β-Lg E was Gly (G) in yak but Glu (E) in bovine. The yak α-LA and β-LG secondary structures were slightly different from those in bovine milk. The denaturation temperatures of yak α-LA and β-LG were 52.1°C and 80.9°C, respectively. This study provides insights relevant to food functionality, food safety control, and the biological properties of yak milk products.     

Antioxidative activity of α-tocopherol in cooked and uncooked ground pork

The effect of α-tocopherol (0, 100, 200 ppm) on lipid oxidation either in cooked or uncooked ground pork was studied during aerobic storage at 4°C and -20°C. Lipid oxidation was measured using the 2-thiobarbituric acid (TBA) method and rancidity development was scored by a trained sensory panel. Alpha-tocopherol slowed the rate of oxidation in cooked ground pork stored at either 4°C or -20°C and uncooked samples refrigerated for extended periods of time (12 days). In cooked product stored at 4°C where oxidation development was intense and off-flavors were strong, panelists did not detect flavor differences due to treatments. But in cooked product stored at -20°C sensory results were consistent with TBA analysis. Pre-rigor grinding, known to induce a high pH and inhibit lipid oxidation in uncooked fresh pork, had no protective effect on lipid oxidation as measured by TBA values in cooked ground pork, regardless of storage condition. TBA numbers increased during storage of cooked product at 4°C with an increase in internal cooking temperature between 50°C and 80°C. Internal cooking temperatures of 70°C or higher induced a rapid rate of oxidation when stored at 4°C.     

Degradation of γ- and α-tocopherol and formation of 5-nitro-γ-tocopherol induced by peroxynitrite in liposomes and skeletal muscle

Peroxynitrite, formed from the reaction between nitric oxide and superoxide, can participate in free radical-mediated reactions with cellular components in muscle to (1) initiate lipid oxidation via the production of lipid hydroperoxides, and (2) produce novel nitrated products. 5-Nitro-γ-tocopherol (NGT) is formed by the electrophilic substitution reaction between peroxynitrite and γ-tocopherol. The objective of this research was to examine the utility of NGT as a lipid-phase, peroxynitrite-specific biomarker in muscle foods. NGT was detected when exogenous peroxynitrite was added to liposomes containing γ-tocopherol and homogenates from chicken dark and turkey light muscle with added γ-tocopherol. Detectable levels of NGT were not observed in either minced turkey light muscle stored at -20?°C or chicken dark muscle stored at 4?°C. These results suggest that NGT is not a suitable biomarker to confirm the presence of endogenously produced peroxynitrite in muscle foods.     

Characterisation of the β-lactoglobulin/α-tocopherol complex and its impact on α-tocopherol stability

β-Lactoglobulin (β-LG), the major whey protein in the milk of ruminants, has a high affinity for small hydrophobic molecules. In the present study, its interaction with lipophilic α-tocopherol, the most abundant and biologically active form of vitamin E, was investigated using circular dichroism, fluorescence, high performance liquid chromatography and turbidity analysis. The interaction did not disrupt the secondary or tertiary structures of β-LG. It was dependent on the aggregation of α-tocopherol and on β-LG/α-tocopherol ratios, with one binding site appearing to be the protein internal cavity and the other in the hydrophobic surface pocket at protein concentrations 1/10 that of the vitamin. Formation of complexes with β-LG increased the solubility of α-tocopherol. The protein also protected α-tocopherol somewhat against decomposition, which depended on the protein concentration and was most effective at a β-LG concentration of one-tenth the α-tocopherol concentration. Protein–nutrient complexes might therefore be useful in the development of functional foods.     

Partitioning of predominant lipophilic bioactives (squalene, α-tocopherol and β-sitosterol) during olive oil processing

The partitioning of predominant lipophilic olive bioactives (squalene, β-sitosterol and α-tocopherol) in olive oil processing was studied for the first time using common integrated olive milling plant. 7% of the oil and 5% of the squalene present in the olives was lost in the last pomace. β-sitosterol and α-tocopherol, which are mainly concentrated in the seed of the olive fruit, was recovered in virgin olive oil to a lesser extent (66%, 67%) while 10% were lost in last pomace. Thus, the loss of β-sitosterol and α-tocopherol was higher than that of squalene and oil, due to nonrecovered bound forms. 19% of the α-tocopherol and 21% of the β-sitosterol loss was unaccounted for, which can be attributed to degradation of α-tocopherol and incomplete recovery of sterols from the olive and pomace matrices. This study provides a basis for process development studies.     

Migration of α-tocopherol and resveratrol from poly(L-lactic acid)/starch blends films into ethanol

Poly(L-lactic acid) (PLLA)/starch blends with various concentrations of two natural antioxidants, α-tocopherol (α-TOC) and resveratrol, were fabricated by a melt blending and compression molding processes. The effects of the two antioxidants on the optical (color), thermal and mechanical properties of PLLA/starch blends with antioxidants were assessed. PLLA/starch blend films with α-TOC and resveratrol showed a yellowish color influenced by the combined effect of white starch and the brown color of the antioxidants. The glass transition and melting temperatures were significantly reduced with the addition of antioxidants while enhanced thermal stability was observed, which could be a benefit and important for processing and production. The enhanced mechanical properties could be attributed to not only a compatibilization effect based on the chemical linkage between PLLA and starch chains, but also restriction of the chain mobility by antioxidants. The release of resveratrol from PLLA and PLLA/starch blend films into ethanol followed Fickian behavior. The D values of α-TOC were in the range of 0.47–3.95 × 10⁻¹¹ cm² s⁻¹ for PLLA films and 0.70–6.83 × 10⁻¹¹ cm² s⁻¹ for PLLA/starch blend films at 13 °C, 5.67–13.0 × 10⁻¹¹ cm² s⁻¹ for PLLA films and 4.10–24.2 × 10⁻¹¹ cm² s⁻¹ for PLLA/starch blend films at 23 °C, and 89.0–118.0 × 10⁻¹¹ cm² s⁻¹ for PLLA films and 123–282 × 10⁻¹¹ cm² s⁻¹ for PLLA/starch blend films at 43 °C. The D values of resveratrol were in the range of 0.073–0.54 × 10⁻¹⁰ cm² s⁻¹ for PLLA films and 1.42–6.93 × 10⁻¹⁰ cm² s⁻¹ for PLLA/starch blend films at 13 °C, 0.90–3.44 × 10⁻¹⁰ cm² s⁻¹ for PLLA films and 4.16–22.3 × 10⁻¹⁰ cm² s⁻¹ for PLLA/starch blend films at 23 °C, and 24.8–74.1 × 10⁻¹⁰ cm² s⁻¹ for PLLA films and 40.1–309 × 10⁻¹⁰ cm² s⁻¹ for PLLA/starch blend films at 43 °C.     

Effect of gamma radiation on levels of α-tocopherol in red meats and turkey

The effect of low dose ionizing radiation on free α-tocopherol levels in beef, pork and lamb longissimus dorsi muscle and on turkey leg and breast muscle were determined. The samples were irradiated in air with a ¹³⁷Cs source at eight dose levels between 0 and 9.4 kGy at 5 °C. Irradiation resulted in a significant decrease in α-tocopherol levels in all of the meats studied. There were no statistically significant differences in the rate of loss of tocopherol due to species, with the exception of turkey breast. The rate of loss of tocopherol in turkey breast tissue was greater than the other meats. The information obtained in this study may be of use for ‘chemiclearance’ purposes since the relative effects due to species variation were examined.     

Biochemical and molecular characterization of polymorphisms of αs1-casein in Sudanese camel (Camelus dromedarius) milk

This work was designed to detect occurrence of biochemical polymorphism of α_s1-casein in two ecotypes of Sudanese camel (Camelus dromedarius) and to characterize these variants on molecular level. Milk samples were screened for α_s1-casein variability by isoelectric focusing, using skimmed milk, as well as isolated α_s1-casein. Two protein patterns, named α_s1-casein A and C, were identified, whereas the major allele A revealed frequencies of 0.8214 and 0.8615 in the two ecotypes. CSN1S1*A and CSN1S1*C are both characterized by missing of exon 16 on mRNA-level compared with the previously described CSN1S1*B. However, the sequence of exon 16 occurs on DNA-level in both. Therefore, this exon seems to be skipped out during mRNA-processing. Furthermore, CSN1S1*C shows a single G > T nucleotide substitution in exon 5, leading to a non-synonymous amino acid exchange (p.Glu30 > Asp30; GenBank ID: JF429138). A polymerase chain reaction-restriction fragment length polymorphism-method was established as a DNA-based test for this nucleotide substitution.     

Electrospinning and characterization of poly (vinyl alcohol)–sericin nanofibers as a potential for tissue engineering applications

Poly vinyl alcohol (PVA) is a hydrophilic, biocompatible, and biodegradable polymer which has found application in biodrugs and tissue engineering. Sericin accompanying silk is a waste which is produced in scouring silk and has interesting properties which has attracted the attention of researchers. Silk sericin is also hydrophilic, biodegradable, and biocompatible. Moreover, it is cheap and anti-cancerous. Mixture of PVA and sericin in the form of 2D membrane or 3D hydrogels has been employed to heal skin damages. This research aimed at electrospinning PVA–sericin blend nanofibers in the form of a mat which has applications in tissue engineering, using dimethyl sulfoxide (DMSO) as an organic solvent. This research showed that the solution of PVA–sericin in DMSO was electrospinnable; however, the addition of urea to the solution made the electrospinning easier. The electrospinning solution contained ratio of 0:100, 10:90, 15:85, 20:80, and 25:75 sericin (%w/w)–PVA (%w/w). The electrospun PVA–sericin nanofibers had an average diameter in the range of 179–285 nm. X-ray diffractometer and differential scanning calorimetry investigations showed no reaction occurring between PVA and sericin. Polyvinyl alcohol 100% was also electrospun in DMSO. Up to now, the electrospinning of PVA in non-aqueous media has not been reported in the literature.     

Effects of rendering and α-tocopherol addition on the oxidative stability of horse fat

Food Science and Biotechnology - Oxidative stability of horse fat rendered at 70&nbsp;°C, − 0.1&nbsp;MPa under vacuum and 110&nbsp;°C, 0.1&nbsp;MPa from horse...     

Enrichment of dry-cured ham with α-linolenic acid and α-tocopherol by the use of linseed oil and α-tocopheryl acetate in pig diets

The use of α-linolenic acid and α-tocopherol enriched pork on the fatty acids and the sensory characteristics of Spanish dry-cured hams have been studied. Five batches of hams were manufactured using the posterior legs of pigs fed on diets with the same ingredients except for the oil source: sunflower (C), linseed (L) or linseed and olive (1/1, w/w, LO). Two different α-tocopheryl acetate concentrations [20 (C, L and LO) or 220 (LOE and LE)mg/kg diet] were used. Biceps femoris and Semitendinosus/Semimembranosus muscles from hams with low polyunsaturated fatty acid n-6/n-3 ratio (less than 3) were obtained from animals fed on linseed and linseed/olive oil enriched diets. However, hams from animals fed on diets added with linseed and α-tocopheryl acetate (20mg/kg diet) (batch L) were rejected by consumers because of less acceptable sensory characteristics and higher TBARs. The remaining hams had satisfactory sensory and nutritional characteristics.