Gamma Irradiation Treatment Research Articles

Postharvest Control of Botrytis cinerea and Monilinia fructigena in Apples by Gamma Irradiation Combined with Fumigation

To extend the shelf life of apples in South Korea, we evaluated the effect of gamma irradiation alone or gamma irradiation combined with fumigation on the control of postharvest decay caused by Botrytis cinerea and Monilinia fructigena. An irradiation dose of 1.0 kGy caused the maximal inhibition of B. cinerea and M. fructigena spore germination. The gamma irradiation dose required to reduce the spore germination by 90% was 0.76 and 0.78 kGy for B. cinerea and M. fructigena, respectively. Inhibition of conidial germination of both fungal pathogens occurred at a greater level at the doses of 0.2 to 1.0 kGy compared with the nontreated control; 0.2 kGy caused 90.5 and 73.9% inhibition of B. cinerea and M. fructigena, respectively. Treatment in vitro with the ecofriendly fumigant ethanedinitrile had a greater effect compared with the nontreated control. The in vitro antifungal effects of the gamma irradiation and fumigation treatments allowed us to further study the effects of the combined treatments. Interestingly, when irradiation was combined with fumigation, the percentage of disease inhibition increased more at lower (<0.4 kGy) than at higher doses of irradiation, suggesting that the combined treatments reduced the necessary irradiation dose in phytosanitary irradiation processing under storage conditions.

Effect of Nisin and Gamma Irradiation Treatments on Listeria monocytogenes on Some High Economic Valued Aquaculture Products

K uresel tuketimde balik ve diger su urunleri onemli rol oynamaktadir. Deniz urunleri diger urunlerle kiyasla daha fazla Listeria monocytogenes kontaminasyonu riski tasimaktadir. L. monocytogenes riski belirli uretim yontemleri ile dusurulmelidir. Cesitli calismalar Nisin uygulamasinin tek veya kombine olarak farkli kosullardaki farkli gidalarda etkili oldugunu gostermistir. Bunlara ek olarak, gama isinlama su urunlerinde raf omrunun uzatilmasi ve patojenlerin dekontaminasyonu icin belirgin bir potansiyele sahiptir. Farkli dort adet ekonomik degeri yuksek urune gama isinlamasi Nisin icerecek veya icermeyecek sekilde uygulandi. Sonuclara gore Nisin uygulanmamis gruplarda L. monocytogenes 5 kGy isin dozu ile eradike edilebilirken, Nisin kombinasyonu uygulanmasi gereken dozu 3 kGy seviyesine cekmistir. Buna bagli olarak farkli su urunlerinde, Nisin ve isinlama kombinasyonlarinin L. monocytogenes kontaminasyonunun giderilmesinde beraber uygulanmasinin verimli olacagi dusunulmustur

Evaluation the effect of gamma irradiation on microbial, chemical and sensorial properties of peanut (Arachis hypogaea l.) seeds.

The aim of the present study was to evaluate the possibility to apply gamma radiation treatment for decontaminating and assuring the quality of peanut seeds. The radiation processing was carried out at dose levels of 3, 6 and 9 kGy. The irradiated and non-irradiated (control) samples were stored at room temperature for 12 months, and analyzed for microbial load, proximate composition, sensorial acceptance and chemical properties. The results indicated that gamma irradiation treatment significantly (p < 0.05) reduced microbial load and enhanced the safety of the irradiated samples. The irradiated samples were also acceptable sensorically. The total acidity and total volatile nitrogen (TVBN) contents increased with the increase of radiation dose. Furthermore, in general, no substantial change in proximate constituents was observed amongst the samples. No significant (p > 0.05) differences in the taste, flavor, color and texture score were observed among treatments (0, 3, 6 and 9 kGy). Irradiation protected again bacterial and fungal growth and retained the nutritional components of samples during long-term storage.

Effects of gamma irradiation on physicochemical properties of native and acetylated wheat starches

Effects of gamma irradiation on the physicochemical and crystalline properties of the native and acetylated wheat starches were investigated. Peak, hot paste, cool paste and setback viscosities of both native and acetylated wheat starches decreased continuously and significantly with the increase of the irradiation dose, whereas breakdown viscosity increased after irradiation. However, gamma irradiation only exerted slight effects on thermal and retrogradation properties of both native and acetylated wheat starches. X-ray diffraction and fourier transform infrared spectroscopy revealed that acetylation modification had considerable effects on the molecular structure of wheat starch, and the crystallinity of both untreated and acetylated starches increased slightly with the increase of irradiation dose. However, the V-type crystallinity of amylose-lipid complex was not affected by gamma irradiation treatments with doses up to 9kGy.

The effects of pulsed ultraviolet light, cold atmospheric pressure plasma, and gamma-irradiation on the immunoreactivity of soy protein isolate

Abstract This study investigates the effect of nonthermal processing technologies on soy immunoreactivity. Soy protein isolate was treated with pulsed ultraviolet (PUV) light, direct and remote cold atmospheric pressure plasma (CAPP), and gamma-irradiation (3–100 kGy). Sample weight, surface temperature, hydrogen peroxide content, and pH value have been measured. SDS-PAGE analysis revealed reduced protein intensity bands corresponding to major soy allergens β-conglycinin (Gly m5) and glycinin (Gly m6). Sandwich ELISA using specific mouse monoclonal anti-Gly m5 antibodies (mAbs) confirmed a loss of soy immunoreactivity following PUV light, direct CAPP, and gamma-irradiation with increasing dose and time. The maximum reduction in immunoreactivity (91–100%) in the soluble protein fraction was achieved by direct CAPP as well as PUV light and gamma-irradiation treatment. A decreased immunoreactivity up to 89% was observed for samples treated with remote CAPP. These innovative technologies might have great potential for industrial application due to their effectiveness in reduction of soy immunoreactivity.

Post-harvest treatment of cherry tomatoes by gamma radiation: Microbial and physicochemical parameters evaluation

Abstract The aim of this study was to evaluate the effects of gamma radiation on cherry tomatoes, to assess the potential of irradiation post-harvest treatment for fruit shelf-life extension. Freshly packed cherry tomatoes ( Solanum lycopersicu s var. cerasiforme ) were irradiated at several gamma radiation doses (0.8 kGy up to 5.7 kGy) in a 60 Co chamber. Microbiological parameters, antioxidant activity and quality properties such as texture, color, pH, total soluble solids content, titratable acidity, and sensory parameters, were assessed before and after irradiation and during storage time up to 14 days at 4 °C. Inactivation studies of natural cherry tomatoes microbiota and inoculated potential foodborne pathogens ( Salmonella enterica ; Escherichia coli and Staphylococcus aureus ) were performed. A two log reduction on the microbial load of cherry tomatoes was verified after irradiation at 3.2 kGy, and 14 days of storage at 4 °C. Moreover, a maximum reduction of 11 log on the viability of potential foodborne bacteria was obtained after irradiation at 3.2 kGy on spiked fruits. Regarding fruits quality properties, irradiation caused a decrease in firmness compared with non-irradiated fruit, although it was verified a similar acceptability among fruits non-irradiated and irradiated at 3.2 kGy. Therefore, these results suggest that the irradiation treatment could be advantageous in improving microbial safety of cherry tomatoes and shelf-life extension without affecting significantly its quality attributes. Industrial relevance There is an ever-increasing global demand from consumers for high-quality foods with major emphasis placed on quality and safety attributes. One of the main demands that consumers display is for minimally processed, high-nutrition/low-energy natural foods with no or minimal chemical preservatives. Extending the shelf-life, while improving the food safety, will have a positive impact on both the industry and consumers (and potential target groups such as immunocompromised patients). The present study indicated that post-harvest gamma radiation treatment of cherry tomatoes can be used as an emergent, clean and environmental friendly process to extend the shelf-life of this fruit with safety and quality.

Single-trap kinetic in Si nanowire FETs: effect of gamma radiation treatment

ABSTRACTHere we report on the effect of gamma radiation treatment on transport properties and single-trap kinetics in Si nanowire (NW) field effect transistor (FET) structures. We used noise spectroscopy as a powerful method for advanced physical characterization of nanoscale devices. Our results demonstrate that transport properties of NW FETs can be changed using small doses of gamma radiation treatment. We reveal an enhancement of the gate coupling effect, which is explained as a result of the reorganization of the native defect structure after treatment. The radiation treatment approach allows the single-trap dynamic to be changed, which opens up prospects for a number of fundamental studies and applications of Si NW FET device structures, including biosensors.

Physicochemical changes in GRAS coated and gamma radiated water chestnut (Trapa bispinosa Roxburg) during ambient storage in different storage structures

The effects of gamma radiation (control, 0.25kGy, 0.50kGy, 0.75kGy, 1.00kGy) and dip treatment of liquid paraffin wax (12%) on the physico-chemical quality of freshly harvested dried water chestnut (Trapa bispinosa Roxburg), packed in glass jar, tin container and low density polyethylene (250 gauge), and the radiation sensitivity of lesser grain borer in gamma radiated samples was analyzed by inoculation of 15 lesser grain borer pest during a period of 6 months at room temperature. The data on the basis of physical properties revealed that weight loss, damage per cent and number of lesser grain borer was found to be 8.93-14.46, 6-24.5 percent and 2-18 borers. The chemical composition ranged from viz; moisture (9.40-10.10), protein (8.82-8.87), fat (0.90-1.00), carbohydrate (76.83-76.87), total ash (3.15-4.03). The effect of gamma radiation and liquid paraffin wax coating on total sugar, reducing sugar, phenol and acidity, and ascorbic acid were from 5.83-5.88, 1.84-1.87, 0.14-0.16, 0.11-0.12 per cent and 41.66-50.00mg/100g respectively. Statistical analysis reveals significant difference in physical parameters (weight loss and damage percent) however in case of chemical composition, throughout the storage period a marginal changes was observed in 0, 3 and 6 months. Irradiation had no appreciable effect on chemical parameters. The treatment combination W4R4 (12% liquid paraffin wax and 1.00kGy) stored in tin container was found to be the best and can extend shelf life up to 6 month without losing the quality of stored water chestnut.

Evaluating the Effects of Gamma-Irradiation for Decontamination of Medicinal Cannabis.

In several countries with a National medicinal cannabis program, pharmaceutical regulations specify that herbal cannabis products must adhere to strict safety standards regarding microbial contamination. Treatment by gamma irradiation currently seems the only method available to meet these requirements. We evaluated the effects of irradiation treatment of four different cannabis varieties covering different chemical compositions. Samples were compared before and after standard gamma-irradiation treatment by performing quantitative UPLC analysis of major cannabinoids, as well as qualitative GC analysis of full cannabinoid and terpene profiles. In addition, water content and microscopic appearance of the cannabis flowers was evaluated. This study found that treatment did not cause changes in the content of THC and CBD, generally considered as the most important therapeutically active components of medicinal cannabis. Likewise, the water content and the microscopic structure of the dried cannabis flowers were not altered by standard irradiation protocol in the cannabis varieties studied. The effect of gamma-irradiation was limited to a reduction of some terpenes present in the cannabis, but keeping the terpene profile qualitatively the same. Based on the results presented in this report, gamma irradiation of herbal cannabis remains the recommended method of decontamination, at least until other more generally accepted methods have been developed and validated.

Effect of gamma irradiation and extended storage on selected chemical constituents and antioxidant activities of sliced mushroom

Due to its exquisite odor and taste, Boletus edulis Bull.: Fr. mushroom is being increasingly used throughout the world. However, the availability of this product is highly restrained by its seasonality and perishability, demanding special care to keep its quality. Furthermore, mushrooms are often distributed in sliced form, and the slicing operation requires special treatments, besides augmenting the possibility of microbial contamination. Some techniques are currently applied to sliced mushrooms, but these processes had adverse effects on nutrients, odor, texture and taste, besides requiring expensive equipment. Food irradiation is being studied as an alternative technology to improve the quality and durability of determined products, having been previously applied in several mushroom species. Herein, gamma irradiation was applied to dried and sliced samples of B. edulis, at high doses (2, 6 and 10 kGy), and the effects on nutritional, chemical and antioxidant parameters were evaluated throughout storage (6 and 12 months). The results obtained for the chemical parameters do not advised storing B. edulis for such extended periods, since some relevant changes were detected, especially in samples stored for 12 months. In general, the gamma irradiation treatment did not cause further changes in the chemical composition, besides having a slightly positive effect in keeping the antioxidant activity and most of the bioactive compounds profiled in this work, contributing to maintain the potential health effects of this exquisite food, even after extended storage periods.

Effect of Gamma Irradiation on Peanut (Arachis Hypogaea.L)

This work report the effect of irradiation with gamma rays (1, 2 and 3 kGy) on the chemical composition, microbial loads, chemical characteristics and sensorial properties of the peanut seeds. The data obtained from the experiments showed that gamma irradiation process has no effect on the proximate composition (water content, proteins, sugars, lipids, and ash), and chemical attributes (free fatty acids, pH value and based nitrogen value (BVN)) of peanut seeds. Irradiation was found to cause significant reduction in microbial load and no fungal colonies were detected in irradiated samples with 2 and 3 kGy. Bacterial and fungal load of irradiated peanut seeds and there comparison with control samples suggest that gamma irradiation treatment at low doses is an effective post-harvest treatment and quarantine control for fungal load. However, non-irradiated and irradiated peanut seeds did not show significant differences in the sensorial test (texture, odor, color and test).

Perturbation of pharmacologically relevant polyphenolic compounds in Moringa oleifera against photo-oxidative damages imposed by gamma radiation

Oxidative stress is a physiological state associated with almost all biotic and abiotic stresses in plants. This phenomenon occurs due to imbalances which result from the overproduction of reactive oxygen species (ROS). Plants, however, have developed sophisticated mechanisms to mitigate the effect of ROS. In this regard, plant polyphenolic metabolites such as flavonoids are known to possess high antioxidant activities. In the current study, changes in the levels of phenolic compounds from Moringa oleifera after gamma radiation treatment were investigated with reverse phase liquid chromatography and mass spectrometric techniques in combination with multivariate data models such as principal component analysis and orthogonal projection to latent structures discriminant analysis. Our results revealed several polyphenolic compounds such as hydroxycinnamoyl derivatives and flavonoid molecules to be down-regulated post-radiation treatment. Interestingly, other flavonoid molecules were found to be up-regulated post-radiation treatment, thereby suggesting a possible compensatory phenomenon. The existence and involvement of structurally similar metabolites (such as regio-isomers of chlorogenic acids) in M. oleifera towards mitigating photo-oxidative damages are in support of the proposed evolutionary existence of a large pool of polyphenolics which contribute to the state of readiness, aptly described as a “better safe than sorry” phenomenon. Our study thus reaffirms the involvement of phenolic compounds as a first line of constitutive/preformed protection against oxidative stress. Furthermore, the obtained data supports M. oleifera as a source of versatile and pharmacologically relevant metabolites that may be exploited for ameliorating the oxidative damages imposed by several metabolic disorders in humans.

Comparative sorption isotherms of conserved Thymus satureioides

Thymus satureioides is an endemic plant of Morocco used for its virtues in traditional medicine. This natural plant in comparison with the preserved one by gamma irradiation and thermal-biochemical treatment using a solar dryer, were investigated at various temperatures and water activity using a saturated salt solution method. Thus, it was necessary to study the effect of preservation processes on the storage conditions. The sorption curves of thyme decreased with the increase in temperature at constant relative humidity and the hysteresis effects were observed. The experimental data of sorption were described by six equations. The Enderby’s model was found to be the most suitable for describing the sorption curves for untreated and irradiated thyme. In opposition, treated thyme was approached by Peleg’s model. Moreover, the optimum water activity of storage was investigated.

Evolutionary mechanism of the defects in the fluoride-containing phosphate based glasses induced by gamma radiation

In the laser driven inertial confinement fusion (ICF) experimental target chamber, like the 3ω (351 nm) laser irradiation, the irradiation of gamma ray and X-rays, will also cause the formation and increase of various defects in the investigated series of fluoride-containing phosphate based glasses that have potential use in novel high performance color separation optics. The induced defects contribute to the increase of absorption in the UV region, which will make the UV performance of these laser glasses deteriorated. Some of the induced defects can be bleached to some extent through the subsequent thermal treatment process, resulting from the release and capture of the electrons in conduction band. Through the gamma radiation and post-heat treatment experiments, a general model of the evolutionary mechanism of the defects in these fluoride-containing phosphate based glasses was proposed.

A Biodegradation Bench Study of Cork Wastewater using Gamma Radiation

AbstractWastewater from cork processing industry present high levels of organic compounds such as phenolics that must be degraded before discharge into the municipal sewer or into public water courses. The aim of this work was to find out if gamma radiation treatment could increase the biodegradability of recalcitrant compounds using a microbial consortium and a mixed solution of four phenolic acids as a model. Chemical and microbiological analyses were performed in non-irradiated (0 kGy) and irradiated (100 kGy) mixed phenolic acids cultures during incubation time. A preliminary HPLC and GC-MS analysis were performed to detect the major phenolic compounds in cork wastewater samples. Results indicated the presence of gallic, protocatechuic, vanillic and syringic acids in cork boiling water and gallic, protocatechuic and vanillic acids in sediment tank samples. The Total Phenolic content (TP) of mixed phenolic acids cultures during incubation time indicated a decrease of 38% for 100 kGy samples. The HPLC analysis suggested that the radiolytic products of syringic and vanillic acids are protocatechuic and gallic acids. The CFU counts pointed out to a decreasing tendency along the incubation time for phenolic acids cultures (0 kGy and 100 kGy) suggesting a non-degradation trend. The selected microbial consortium was not able to metabolize the phenolic compounds solutions at the used conditions. This could be due to the detected radiolytic degradation dynamics of the phenolic acids considering the antimicrobial activity of these compounds.

Effects of Gamma Radiation and Heat Treatment on the Photoluminescence of the Fluoride-Containing Phosphate-Based Glasses

We demonstrate, for the first time to our knowledge, two different balances around fluorine-related non-paramagnetic color (FD) centers in fluoride containing phosphate based optical filter glasses at low (190°C) and higher (390°C) heat-treatment temperature, respectively. The thermal bleaching experiment results indicate the heat-treatment bleached gamma radiation induced phosphate-related oxygen hole center (POHC) and oxygen-related hole center (OHC) to some extent due to the release and capture of the electrons in the conduction band. Through the gamma radiation and subsequent heat-treatment experiment, as well as the detailed analysis of photoluminescence and excitation spectra, a general model corresponding to the two different balances about the FD defects and the evolutionary mechanism of these existing defects in the fluoride-containing phosphate based glasses was proposed.

In vitro radio-sensitivity (Gamma irradiation) of some juice and wine making grape genotypes

Irradiation sensitivity of four juice and wine genotypes i.e., Pusa Navrang, Pearl of Csaba, Hybrid 76-1 and Julesky Muscat was ascertained. Well proliferated cultures these genotypes were raised on standardized proliferation cum rooting medium (MS basal medium + 2.0 mg/l IBA + 250 mg/l activated charcoal) were subjected to Gamma irradiation treatments (0, 5, 15, 20, and 25 Gy). The cultures after irradiation were sub-cultured following in vitro repetitive micro-cutting technique on the same medium upto five cycles (vM5). Thereafter, the in vitro rooted plantlets were hardened and later transferred in pots in glasshouse for survival and morphological analysis. Results showed that the highest mean explant survival was noted in the control (83.78%) over other irradiation dosages except 5 Gy dose (80.95%), which were at par. The gamma irradiation dose of 10 Gy gave the mean survival of 46.66%, shoot sprouting (56.85%) and in vitro shoot abnormalities (50.59%), which were significantly different from the other irradiation dosages. The 10 Gy irradiation dose was recorded as a lethal dose 50 (LD50) for all genotypes. However, as the irradiation dose was increased further, the explant survival percentage, shoot sprouting and in vitro shoot and root abnormalities significantly enhanced. The highest shoot sprouting was noted in Pusa Navrang (57.59%) followed by Pearl of Csaba (55.59%). Surviving mutants showed altered physiological traits with increasing doses of Gamma irradiation.

Mutagenic Effects of Gamma Radiation on Eight Accessions of Cowpea (&amp;lt;i&amp;gt;Vigna unguiculata&amp;lt;/i&amp;gt; [L.] Walp.)

Mutagenesis is used for creating new genetic variability in cultivar improvement. Optimal mutagenic treatment is required for effective mutation induction in crop species. Therefore, radio-sensitivity of cowpea accessions to gamma irradiation was investigated. Seeds of eight cowpea accessions were irradiated with 60Co gamma radiation doses of 100, 200, 300, 400 and 500 Gy. The seeds were sown in pots to evaluate the treatment effects on seed germination (SG), seedling survival (SS) and growth habits of M1 generation. Data were analyzed using descriptive statistics. Low rates of SG (10% - 45%) were recorded at higher doses (500 - 400 Gy) in Ife Brown (IB) and its derivatives, whereas high SG rates (74% - 94%) were observed in IT90K-284-2 across all treatments. Percentage SS was inversely related to gamma dosage. A wide range of LD50 for SG (329 - 1054 Gy) and SS (149 - 620 Gy) were observed across the cowpea accessions. Low LD50 scores for SG (329 - 516 Gy) and SS (149 - 357 Gy) were observed among cowpea with rough seed coat, whereas cowpea with smooth seed coat recorded higher LD50 for SG (521 and 1054 Gy) and SS (449 and 620 Gy). Seed germination LD50 and SS LD50 were highly correlated with mean coat thickness (0.899 and 0.937) than mean seed weight (0.621 and 0.678). Gamma irradiation of cowpea seed at low dosage (100 Gy) increased the vigor of M1 seedlings with respect to primary leaf area, terminal leaflet area, seedling height and plant height at six weeks. Doses of 200 Gy and above resulted in a progressive reduction in vigor of plant and seed setting of cowpea. Radio-sensitivity varied with cowpea genotype and was associated with seed testa texture, thickness and seed weight. Low gamma irradiation treatment (100 Gy) may be used to enhance seedling vigor, vegetative growth and yield of cowpea at M1 generation.

Eff ect of gamma rays on germination, morphological and yield characters of bhendi (Abelmoschus esculentus [L.] Moench)

&lt;p&gt;Bhendi (Abelmoschus esculentus [L.] Moench) is the most common vegetable crop of the world. The genus Abelmoschus belongs to family Malvaceae is represented by 12 species. This investigation was carried out to the study of different doses of gamma irradiation on bhendi seeds of varieties arka anamika. Gamma irradiation treatment at 10, 20, 30, 40, 50, and 60 KR levels. The main objective of the present study is to determine the effect gamma irradiation on different morpho-agronomic characteristics. Agronomic traits were analyzed such as days of first flower, height of plants, number of fruits per plant, fruit length, seed yield per plant, fresh weight per plant, dry weight per plant, 100 seed weight. The seed pre-soaked in distilled water for 6 h before the sown in the field. The results showed that the positive shift with respect to all parameters. High doses of gamma&lt;br /&gt;irradiation (40 and 50 KR) observed in moderate to high values.&lt;/p&gt;

Influence of postharvest gamma irradiation treatment on the content of bioactive compounds and antioxidant activity of fenugreek ( Trigonella foenum–graceum L.) and spinach ( Spinacia oleracea L.) leaves

Abstract Fenugreek and spinach leaves after irradiation in the dose range of 0.25–1.5 kGy were evaluated for the content of bioactive compounds and antioxidant activity using DPPH radical scavenging, ferric reducing ability power (FRAP), hydroxyl radical scavenging and ferrous ion chelating assays. Results of the study revealed that bioactive content except total ascorbic acid was significantly (p ≤ 0.05) higher in fenugreek compared to spinach. Data analysis revealed that gamma irradiation treatment significantly (p ≤ 0.05) enhanced the content of individual as well as total bioactive components of both vegetables. Positive correlation (r = 0.92) existed between gamma irradiation and total phenolics. The results of the antioxidant activity as determined by above mentioned assays revealed a significant (p ≤ 0.05) decrease in EC 50 values and a corresponding increase in antioxidant content and activity due to irradiation. Comparison of the increase in inhibition percentage, reducing power and chelating efficiency revealed that treatment of irradiation was significantly (p ≤ 0.05) effective in enhancing the ferric reducing power of both the vegetables (3.1–37.5% for fenugreek, 4.1–42.8% for spinach) and OH radical scavenging for spinach (1.5–22.4%) compared to fenugreek (0.78–13.1%). The present investigation suggested that postharvest radiation treatment to fenugreek and spinach has a potential to enhance their antioxidant content and activities, besides acting as a photo-sanitary treatment. Industrial relevance The increasing demand of convenience, wholesome and health promoting foods has resulted in search of new technologies to improve the shelf-life and at the same time preserve the nutritional quality. Prolonging postharvest storage, while enhancing the content of bioactive compounds will have a positive impact on both the industry and consumers. The present study demonstrated that postharvest radiation treatment of fenugreek and spinach can be used a novel approach to enhance their bioactive composition and antioxidant activity.