Antioxidant activity in meat treated with oregano and sage essential oils

The antioxidant activity of meat treated (homogenized) with oregano and sage essential oils, during meat storage, was determined using the following assays: a thiobarbituric acid (TBA) assay, a diphenylpicrylhydrazyl (DPPH) assay and a crocin assay. Porcine and bovine ground meat samples were divided into three experimental treatments, namely: control (no antioxidant), oregano (oregano essential oil 3% w/w) and sage (sage essential oil 3% w/w). Subsequently, the samples from each treatment were stored at 4 °C, in the raw and cooked (at 85 °C for 30 min) state, and the antioxidant activity was determined after 1, 4, 8 and 12 days of storage. The results showed that the essential oil treatments significantly reduced the oxidation, while the heat treatment and storage time significantly affected the antioxidant activity of the meat. The role of antioxidants appeared to be much more important in cooked meat than raw and the meat proteins greatly affected the antioxidant activity.     

Structural and antioxidant properties of gamma irradiated hyaluronic acid

Hyaluronic acid (Hyaluronan, HA) was depolymerised by gamma irradiation and its structural changes and antioxidant activities were investigated. The structural changes of gamma irradiated HA were studied by gel-permeation chromatography (GPC), viscosity, pH, Hunter colour measurement, UV spectrophotometry, and FT-IR spectroscopy. The results demonstrated that gamma irradiation decreased molecular weight size, viscosity and pH of the hyaluronic acid and its colour turned to intense yellow. UV spectra of the irradiated HA showed a change at 265 nm, which indicates the formation of double bonds. Differences in the height and shape of certain absorption bonds of FT-IR spectra in the range 1700–1750 cm⁻¹ were also observed, which is associated with the formation of carboxylic acid. From these structural changes of the HA, gamma irradiation may have a role in the formation of pyrancarboxylic acid rings. DPPH radical scavenging ability and the reducing power of gamma irradiated HA were significantly higher than that of non-irradiated HA. However, non-irradiated and irradiated HA did not show significant differences in the Rancimat test.     

Radiation-induced enhancement of antioxidant activity in extracts of rosemary (Rosmarinus officinalis L.)

Dry rosemary leaf powder was subjected to 30 kGy of gamma ray irradiation, followed by solvent extraction with methanol, ethanol or water. The antioxidant activity of the extracts was assessed using the DPPH radical-scavenging method and the reducing power test. EC₅₀ values, using the radical-scavenging method, indicate a 22% increase in the antioxidant activity of ethanol and water extracts as a result of irradiation treatment. EC₅₀ values in the reducing power test show an increase of 45% and 28% for the ethanol and water extracts, respectively. The antioxidant activity of methanol extracts of irradiated rosemary remained the same as in the controls in both types of test. A high correlation was found between the EC₅₀ values obtained in the DPPH radical test and those from the reducing power test. Total phenolic content (Folin–Denis test) increased by 35% in the water extracts as a result of irradiation but remained the same in the methanol and ethanol extracts. The methanol extract showed the highest antioxidant activity and the highest amount of total phenolic compounds. Radiation reduced the good correlation between antioxidant activity and total phenolic content.     

Phenolic content and antioxidant activity of cantaloupe (cucumis melo) methanolic extracts

The objectives of this study were to determine phenolic content and antioxidant activity of methanolic extracts from different parts of cantaloupe (leaf, stem, skin, seed and flesh). The flesh extract afforded the highest yield (89.6 ± 0.3%) whilst the lowest yield was obtained from the seed (13.7 ± 0.5%) (p < 0.05). The leaf extract showed the highest total phenolic content (26.4 ± 0.3 mg GAE/g extract) and total flavonoid content (69.7 ± 3.37 μg RE/g extract) accompanied with best antioxidant activity through all antioxidant assays (p < 0.05). In addition, the stem extract also exhibited good antioxidant activity. Thus, these results suggest that methanolic extracts of cantaloupe leaf and stem may serve as a potential source of natural antioxidant for food and nutraceutical application.     

Enhancement of pasta antioxidant activity with oregano and carrot leaf

Five different pasta formulations were prepared using different concentrations of carrot leaf meal (CLM) and oregano leaf meal (OLM). One control formulation (wheat flour and semolina, 70:30 w/w) and four other formulations were prepared using the following amounts of leaf meals: 5% CLM and 5% OLM (I), 10% CLM (II), 10% OLM (III), and 10% CLM, 10% OLM (IV). The highest content of alpha-linolenic acid was found in formulations II and IV, which also had a reduced n-6/n-3 ratio, 3.6 (IV), when compared to the control, which was 19.8. All the samples enhanced with leaf meals showed antioxidant activity by the DPPH radical method; however, it was higher in formulation IV, which was the same observed for phenolic compounds. Pasta added with leaf meals lost more solubles, had shorter cooking time and a lower weight increase than the control pasta. All formulations had significant sensory acceptance.     

Structural feature and antioxidant activity of low molecular weight laminarin degraded by gamma irradiation

Recently, it has been reported that low molecular weight laminarin had enhanced biological activities. In this study, laminarin was degraded by gamma irradiation, and the changes in its structure and antioxidant property were investigated. Gel permeation chromatography data showed that the average molecular weight of the irradiated laminarin decreased significantly as the irradiation dose increased. The absorbance at 290 nm, from UV spectra, was increased, depending on the irradiation dose and caused by the formation of carbonyl groups. From the NMR analysis, the ratio of β-1,3- to β-1,6-linkages was not changed, indicating the random scission of chains by gamma irradiation. The antioxidative activities, measured by Rancimat test, were all increased in the gamma-irradiated laminarin, depending on the absorbed dose, presumably due to the carbonyl groups formed by gamma irradiation. Therefore, gamma irradiation could be a promising method for preparing low molecular weight laminarin with enhanced biological activities.     

Effect of gamma irradiation on microbial analysis, antioxidant activity, sugar content and color of ready-to-use tamarind juice during storage

Gamma irradiation is highly effective in inactivating microorganisms in various foods and it offers a safe alternative method of food decontamination. In the present study, the effect of gamma irradiation on microbial analysis, antioxidant activity, sugar content, color and sensory evaluation of ready-to-use tamarind juice was investigated during storage. A fresh tamarind juice was prepared by dissolving 5 g of pulp/100 ml of deionized distilled water and irradiated at 0, 1, 3 and 5 kGy at room temperature. Microbiological assay of the fresh and stored ready-to-use tamarind juice showed better quality after gamma irradiation. Antioxidant ability was studied by using 1,1-diphenyl-2-picrylhydrazyl (DPPH), FRAP (ferric reducing/antioxidant power) and total phenolic contents, and gamma irradiation had a significant increase or maintenance on the antioxidant potential of the ready-to-use tamarind juice. Contents of glucose and fructose also showed minimal alterations both in the fresh and stored samples. There was a significant improvement in the Hunter color value in both the fresh and stored tamarind juice. To conclude, gamma irradiation improves the microbial decontamination and the antioxidants as well as the color of the ready-to-use tamarind juice without any adverse change in sensory qualities.     

Variation of active constituents and antioxidant activity in pyrola [P. incarnata Fisch.] from different sites in Northeast China

The variation of antioxidant activity and active components in pyrola [Passiflora incarnata Fisch.] from eight sites in Northeast China were investigated. Total phenolic and flavonoid contents were determined and varied within the range of 39.66–181.48 mg/g and 2.47–22.11 mg/g, respectively. Antioxidant activities were determined by scavenging activity against DPPH and ABTS, by a reducing power test and by a β-carotene-linoleic acid bleaching test. The IC₅₀ of Tahe samples determined by the DPPH test was 0.106 ± 0.006 mg/mL which was very close to that of Vc (0.076 ± 0.004 mg/mL). The Tahe samples had good antioxidant activity. Principal component activity analysis indicated that the Tahe samples of P. incarnata had the highest potential antioxidant properties, and may be a valuable antioxidant natural resource in the northeast of China.     

Effect of gamma irradiation on the extraction yield, total phenolic content and free radical-scavenging activity of Nigella staiva seed

In the present study, the radiation processing of Nigella sativa seed samples was carried out at dose levels of 2, 4, 8, 10, 12 and 16 kGy. The extraction yield, total phenolic content and 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical-scavenging activity of both control and irradiated samples extracted in acetone, methanol and water were assessed. The results showed that the extraction yields increased with an increase in radiation dose for all the test solvents. At 16 kGy the increases were 3.7%, 4.2%, 5.6% and 9.0% for hexane, acetone, water and methanol extracts, respectively. The phenolic content in the acetone extract was found to be increased from 3.7 for the control sample to 3.8 mg/g for the 16 kGy radiation-processed sample. No significant change was observed for the phenolic content of the methanolic extract, while the aqueous extract showed a decrease at dose levels of 12 and 16 kGy. In the control samples, the DPPH radical-scavenging activity was 79.4%, 79.1% and 92.0% for water, acetone and methanol extracts, respectively, at 5 mg/ml concentration. Gamma irradiation enhanced the scavenging activity in acetone and methanol extracts by 10.6% and 5.4%, respectively, at 16 kGy. In summary, gamma irradiation increased the extraction yield and total phenolic content, as well as enhancing the free radical-scavenging activity. In addition, the type of solvent used for extraction also affected the impact of irradiation on antioxidant activity and total phenolic content of N. sativa seed.     

Antioxidant and polyphenol oxidase activity of germinated barley and its milling fractions

Eight different hulled barley cultivars were evaluated before and after germination for total phenolic content (TPC), antioxidant activity (AOA) and polyphenol oxidase (PPO) activity. Germination for 12 h significantly decreased the TPC in whole flour (WF), bran (B) and refined flour (RF), however, further increase in germination to 24 h significantly increased the TPC in the fractions. Germination for 12 h duration significantly increased the AOA for WF, B and RF and further increase in germination to 24 h significantly increased the AOA in all the barley cultivars tested. A strong positive correlation was observed between AOA and TPC. Upon germination for 12 h the polyphenol oxidase activity of WF, B and RF significantly decreased by 13.31–59.22, 1.93–59.46 and 7.08–45.87%, respectively, however, the PPO activity increased upon germination for 24 h. The highest level of TPC and AOA was observed in the bran fraction of all the barley cultivars.     

Effect of salt stress on phenolic compounds,glucosinolates, myrosinase and antioxidant activity in radish sprouts

The germination, growth, total phenolics, glucosinolate, myrosinase and antioxidant activity of radish sprouts germinated under 0 (control), 10, 50 and 100 mM of NaCl were investigated. The glucoraphasatin (4-methylthio-3-butenyl-glucosinolate), total glucosinolate and total phenolic contents of 5- and 7-day-old sprouts treated with 10 and 50 mM of NaCl were significantly decreased. However, the antioxidant activity of sprouts treated with 10 and 50 mM of NaCl was not affected. The glucoraphasatin and total glucosinolate contents of 5- and 7-day-old sprouts, total phenolic contents of 3- and 5-day-old sprouts were significantly increased and myrosinase activities of 3- and 5-day-old sprouts were inhibited, although the germination was dramatically inhibited by 100 mM of NaCl treatment. These results indicated that salt stress (100 mM of NaCl treatment) could improve the nutritional value of radish sprouts, and germination of sprouts under adequate salt stress could be one useful way to enhance health-promoting compounds of plant food.     

Phenolic composition,colour, antioxidant activity and mineral profile of Cabernet Sauvignon wines

Phenolic compounds and mineral content constitute important quality parameters of wines. It is probably during ageing, that the greatest number of polymerisation and condensation reactions occurs, notably modifying the composition of the wine. The aim of this study was to characterise Cabernet Sauvignon wines of different vintages from two regions in Santa Catarina State, Brazil. It was not possible to clearly observe an evolution of the phenolic content and colour parameters in the different vintages of the wines. The ABTS method gave higher antioxidant value than DPPH, which showed higher correlation with total polyphenols. Principal components analysis showed differences between the wines, especially in relation to vintage. Also, the study allowed a clear separation of wines in relation to place of vineyards in terms of mineral composition.     

Phenolic Content and Antioxidant Activity of Germinated and Cooked Pulses

Five commonly consumed pulses, Mah (Vigna mungo), Green mung (Vigna radiata), Arhar (Cajanas cajan), Masur (Lens esculantus), and Moth (Vigna aconitifolia), were studied for their total phenolic content and antioxidant activity after germination (12 and 24 h) and pressure cooking. Arhar had the highest total phenolic content (6.71 mg ferulic acid/g flour) whereas Moth had the least (1.54 mg/g). All pulses, except Moth, showed a significant decrease in total phenolic content after germination. The antioxidant activity of the pulses varied from 10.61 to 36.38% (DPPH radical scavenging activity), which significantly decreased with germination in all pulses except Moth. The total phenolic content highly correlated with the antioxidant activity in the pulses. Cooking lowered the total phenolic content by 10–45% and antioxidant activity by 27–68% in the control and germinated pulses.     

Changes in colour and antioxidant activities of Hizikia fusiformis cooking drips by gamma irradiation

To utilize the cooking drips produced during the seaweed drying process, the effect of gamma irradiation on microbial contamination, colour, and antioxidant activities of Hizikia fusiformis cooking drips (HCD) was investigated. A two log cycles reduction of total aerobic bacteria and yeast and moulds counts was obtained irradiating HCD at 1 kGy. The Hunter L^∗ value of the HCD ethanol extract was increased by the gamma irradiation treatment, but the a^∗ and b^∗ values decreased upon irradiation depending on the absorbed dose. The 1,1-diphenyl-2-picrylhydrazyl radical scavenging and β-carotene bleaching activities of the HCD extracts increased as a result of gamma irradiation, which was rationalized by the observed increase in polyphenolic compounds content. These results suggest that wasted cooking drips can be used as a functional component by the food and cosmetic industries if the irradiation technology were applied.     

Evaluation of the antioxidant activity of asparagus,broccoli and their juices

Antioxidant activity of asparagus, broccoli and their juices was evaluated using 2,2′-diphenyl-l-picrylhydrazyl (DPPH), 2,2′-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and β-carotene bleaching assays. Asparagus showed greater antioxidant activity than broccoli. Asparagus juice also had greater antioxidant activity than broccoli juice. Methanol and acetone extracts of asparagus and broccoli had significantly greater antioxidant activity than their water extracts. Asparagus and broccoli extracts, as well as their juices, showed no significant difference in total phenolics content. However, asparagus contained more flavonoids than broccoli. The antioxidant activity of asparagus and broccoli extracts demonstrated a linear relationship with their flavonoid content.     

Effect of agitated bed drying on the retention of phenolic compounds,anthocyanins and antioxidant activity of roselle (Hibiscus sabdariffa L.)

An agitated fluidised bed dryer was employed to dry lixiviated roselle (Hibiscus sabdariffa L.) calyxes. The effects of operational drying variables on the chemical attributes such as the retention of monomeric anthocyanins (MA), phenolic compounds, polymeric colour, antioxidant activity and drying rate were analysed. Drying curves showed only decreasing falling rate period. To determine the kinetic parameters, the drying data were fitted to a Page's model, based on the moisture content ratio vs. the drying time; the k values ranged from 1.58 × 10^?5 to 6.28 × 10^?2 s^?1. The different drying conditions showed significant differences in the chemical parameters. When processing wet feeds, as lixiviated roselle calyxes, the mechanical assisted fluidisation can be considered as an innovative concept.     

Impact of oregano and virgin olive oil phenolic compounds on acrylamide content in a model system and fresh potatoes

In this study the effect of olive oil and oregano phenolic compounds on antioxidant activity (AOA) and acrylamide formation in a model system and fresh potatoes was evaluated. The addition of oregano phenolic extract in the model system resulted in an increase of AOA and in a reduction of acrylamide content, up to 49%, after heating. On the contrary, addition of olive oil extract resulted in AOA reduction and a concentration-dependent effect on acrylamide formation was observed with a reduction up to 15% (p < 0.05) followed by an increase up to 48%. The same trend, in acrylamide formation, was observed in fresh potatoes but to a lower extent. Finally, addition of tyrosol, oleuropein and p-hydroxyphenylacetic acid in the model system resulted in acrylamide reduction up to 50%. The discrepancy in acrylamide formation, caused by phenolic compounds, is ascribed to their structure and related to their terminal functional hydroxyl and aldehydic groups.     

Antioxidant and antibacterial activity of leaves of Etlingera species (Zingiberaceae) in Peninsular Malaysia

Methanolic extracts from fresh leaves of five Etlingera species were screened for total phenolic content (TPC), antioxidant activity (AOA), and antibacterial activity. Analysis of TPC was done using the Folin–Ciocalteu method. Evaluations of AOA included 1,1-diphenyl-2-picrylhydrazyl free radical-scavenging ability, ferric-reducing antioxidant power (FRAP), ferrous-ion chelating (FIC) ability, and β-carotene bleaching (BCB) activity. Antibacterial activity was screened using the disc-diffusion method. Highest TPC, ascorbic acid equivalent antioxidant capacity (AEAC), and FRAP were found in leaves of E. elatior and E. rubrostriata. Leaves of E. maingayi, with the lowest TPC, AEAC, and FRAP, had the highest FIC ability and BCB activity. Ranking of TPC and AOA of different plant parts of E. elatior was in the order: leaves > inflorescences > rhizomes. Leaves of highland populations of Etlingera species displayed higher values of TPC and AEAC than those of lowland counterparts. Leaves of Etlingera species exhibited antibacterial activity against Gram-positive but not Gram-negative bacteria.