High hydrostatic pressure treatment as an alternative to pasteurization to maintain bioactive compound content and texture in red sweet pepper

Red sweet peppers (Capsicum annuum) are an excellent source of essential nutrients and bioactive compounds. High hydrostatic pressures (HHP) not only increase shelf-life but also maintain nutritional and organoleptic properties better in a number of food products. The aim of this work was to measure the effect of HHP and a thermal treatment, pasteurization (PA) in a water bath at 70 °C for 10 min, on some bioactive compounds (fibre, carotenoids and antioxidant activity) and on the texture (TPA; firmness and shear force) of red Lamuyo-type sweet peppers, in order to discover the relationship between treatment (HHP and PA), tissue microstructure and bioactive compound extractability. The results show that HHP at 500 MPa and PA treatments had less impact on the microstructure, bioactive compound content (fibre and antioxidant activity) and texture of red sweet peppers, than when low pressures were used. Consequently, new functional foods could be developed using red sweet pepper tissues treated with high pressures (500 MPa) and/or PA.Industrial relevanceToday’s consumers demand foods that are rich in bioactive compounds with beneficial health effects and safer, more natural, minimally-processed food products. Red sweet peppers (Capsicum annuum) are an excellent source of essential nutrients and bioactive compounds such as carotenoids and fibre. High hydrostatic pressure (HHP) processing is considered one of the most economically viable of the non-thermal technologies that helps to preserve red sweet peppers with high nutritional and quality parameters. Therefore, it would be interesting to study the microstructure of HHP-treated red sweet pepper tissues in order to discover whether this treatment promotes the extractability of bioactive compounds, and to compare the results with those obtained by pasteurizing the red sweet pepper. Thus, these enhanced red sweet peppers could be used as ingredients in the formulation of new functional foods.     

Antioxidant capacity and hydrophilic phytochemicals in commercially grown native Australian fruits

Hydrophilic phytochemicals and antioxidant capacities of eight commercially grown native Australian fruits were determined. Kakadu plum (Terminalia ferdinandiana) contained a 6-fold higher level of total phenolic compounds and quandong (Santalum acuminatum) a 1.9-fold higher level of total phenolic compounds (TP, Folin–Ciocalteu assay) than blueberry (Vaccinum sp., cv. Biloxi). Both fruits displayed superior oxygen radical-scavenging capacity (ORAC-H assay) that was, respectively 4.1-fold and 6.5-fold of that of blueberry. The total reducing capacity (TRC; ferric reducing antioxidant power (FRAP) assay) of Kakadu plum and quandong exceeded the TRC of blueberry, respectively, 13.1- and 2.3-times. The primary sources of antioxidant capacities in the evaluated fruits were phenolic acids (benzoic and cinnamic) and flavonoids (flavonols, flavanones and anthocyanins) tentatively detected by liquid chromatography–mass spectrometry (LC–PDA–MS/MS). A high level of vitamin C was recorded for Kakadu plum and Australian citrus fruits. The major organic acids detected were citric and malic acid.     

Fruit quality and bioactive compounds relevant to human health of sweet cherry (Prunus avium L.) cultivars grown in Italy

The fruit quality characteristics, phenolic compounds and antioxidant capacities of 24 sweet cherry (Prunus avium L.) cultivars grown on the mountainsides of the Etna volcano (Sicily, Italy) were evaluated. High-performance liquid chromatographic methods were used to identify and quantify sugars, organic acids and phenolics. A total of seven phenolic compounds were characterised as hydroxycinnamic acid derivatives (neochlorogenic acid, p-coumaroylquinic acid and chlorogenic acid) and anthocyanins (cyanidin 3-glucoside, cyanidin 3-rutinoside, pelargonidin 3-rutinoside and peonidin 3-rutinoside). The total anthocyanin content ranged from 6.21 to 94.20 mg cyanidin 3-glucoside equivalents/100 g fresh weight (FW), while the total phenol content ranged from 84.96 to 162.21 mg gallic acid equivalents/100 g FW. The oxygen radical absorbance capacity (ORAC) assay indicated that fruit of all genotypes possessed considerable antioxidant activity. The high level of phenolic compounds and antioxidant capacity of some sweet cherry fruits implied that they might be sources of bioactive compounds that are relevant to human health.     

Bioactive Compounds and Fruit Quality of Green Sweet Pepper Grown under Different Colored Shade Netting during Postharvest Storage

In this study, influence of 3 types of photo‐selective nets (pearl, red and yellow) and a standard black net on marketable yield, fruit quality and bioactive compounds after postharvest storage was investigated. Percentage marketable fruits were higher in green sweet peppers produced under the pearl nets. Fruits produced under the pearl nets showed higher fruit mass, firmness, chlorophyll content, ascorbic acid content, antioxidant scavenging activity after postharvest storage. Red/far red photon ratio under the pearl net could have improved the ascorbic acid content and the antioxidant scavenging activity in green peppers. Green sweet peppers grown under the pearl nets had higher hue values and maintained green color longer. Our results showed the impact of modified light quality on the bioactive compounds of green sweet pepper during postharvest storage.     

Blanching peppers using microwaves

Enzymatic reactions are not desirable in ripe fruits and vegetables. They cause losses along transportation, storage and processing. Blanching is a pre-treatment operation whose aim is to inactivate enzymes, and is usually applied before cutting, peeling, and freezing in order to avoid browning and changes in texture. Besides inactivating enzymes such as polyphenoloxidase, peroxidase and pectinase, blanching may induce sensory and chemical changes. The purpose of this work was to evaluate changes in antioxidant activity of Capsicum annuum Jalapeño type, when treating with microwaves to inactivate polyphenoloxidase. The whole fresh peppers (85% moisture) were blended until a paste was obtained. Ten grams portions were placed in a glass container and processed in a microwave oven until the inactivation of polyphenoloxidase was reached. Inactivation of the enzyme was confirmed with a spectrophotometric method using catechol as substrate. The processed peppers samples were mixed with 80% ethanol to extract phenolic compounds that were determined by the Folin Ciocalteu method. The antioxidant activity was evaluated using the radical ABTS, as described by Charurin et al (2002). Results showed that phenolic compounds were reduced from 9.6 to 7.6 mg/ g peppers (dry weight basis) and antioxidant activity was enhanced from 29 to 42 μM de trolox/ g peppers (dry weight basis) with thermal microwave blanching. Changes in the content of phenolic compounds were confirmed using high performance liquid chromatography, and the emergence of other phenol derivatives with enhanced antioxidant activity was detected in blanched samples. It may be concluded that blanching Jalapeño peppers with microwaves may induce the formation of derivatives of phenolics with enhanced antioxidant activity.     

Antioxidant activities of different colored sweet bell peppers (Capsicum annuum L.)

ABSTRACT:  Antioxidant compounds and their antioxidant activity in 4 different colored (green, yellow, orange, and red) sweet bell peppers ( Capsicum annuum L.) were investigated. The total phenolics content of green, yellow, orange, and red peppers determined by the Folin-Ciocalteau method were 2.4, 3.3, 3.4, and 4.2 μmol catechin equivalent/g fresh weight, respectively. The red pepper had significantly higher total phenolics content than the green pepper. Among the 4 different colored peppers, red pepper contained a higher level of β-carotene (5.4 μg/g), capsanthin (8.0 μg/g), quercetin (34.0 μg/g), and luteolin (11.0 μg/g). The yellow pepper had the lowest β-carotene content (0.2 μg/g), while the green one had undetectable capsanthin and the lowest content of luteolin (2.0 μg/g). The free radical scavenging abilities of peppers determined by the 2,2'-diphenyl-1-picrylhydrazyl (DPPH) method were lowest for the green pepper (2.1 μmol Trolox equivalent/g) but not significantly different from the other 3 peppers. All 4 colored peppers exhibited significant abilities in preventing the oxidation of cholesterol or docosahexaenoic acid (DHA) (C22:6) during heating. However, these 4 peppers did not show significant differences in their abilities in preventing cholesterol oxidation. The green pepper showed slightly higher capability in preventing the oxidation of DHA compared to the other 3 peppers.     

Effects of chitosan coating enriched with cinnamon oil on qualitative properties of sweet pepper (Capsicum annuum L.)

Effect of chitosan–oil coating on qualitative properties of sweet pepper (Capsicum annuum L.) stored at 8 °C for 35 days was investigated. The chitosan–oil coating treatment exhibited the best control effect on decay (below 5%). At the end of storage, samples treated with chitosan-oil coatings maintained good sensory acceptability, whereas the sensory quality of control samples became unacceptable. The higher activities of scavenger antioxidant enzymes, including superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT), in treated peppers at the 35th day should be contributed to the chitosan–oil coating. Malondialdehyde (MDA) and electrolyte leakage contents in chitosan–oil-coated peppers were increased but were still lower than in control samples. Atomic force microscopy images showed that the surface of sweet pepper without coating treatment was rougher than that of peppers treated with chitosan–oil coating. Our study suggests that chitosan–oil coating might be a promising candidate for enhancing the keeping quality of sweet peppers.     

In vitro antioxidant, antimicrobial, and antitumor activities of bitter almond and sweet apricot (Prunus armeniaca L.) kernels

The aim of this study was to investigate in vitro antioxidant, antimicrobial, and antitumor activities of water, methanol, and ethanol extracts of sweet apricot and bitter almond kernels. The fruit extracts were evaluated for their antioxidant activities using various antioxidant methodologies including phosphomolybdenum assay (total antioxidant capacity), free radical scavenging assay, ferric ion reducing power, and β-carotene/linoleic acid bleaching test system. The antioxidant capacity of the sweet apricot kernels was better than those recorded for bitter almond ones. The highest total antioxidant activity (59.53 mg/g dry extract), ferric ion reducing power (1.626), antioxidant index (67%), total phenolic content (3.290 mg/g dry extract), and total lycopene content (4.70mg/mL) were detected in the aqueous extract of sweet apricot kernels. The antimicrobial activities of the above extracts were also tested against some pathogenic microorganisms using a disc-diffusion method. Additionally, the extracts of sweet apricot and bitter almond kernels could inhibit the growth of human breast (MCF-7), colon (HCT-116), and hepatocellular (Hep-G2) carcinoma cell lines in a dose-dependent manner with different sensitivity between cell lines. The overall results indicate promising baseline information for the potential uses of apricot (Prunus armeniaca L.) fruit extracts in the treatment of infectious diseases and tumors.     

Bioactive characteristics and antioxidant activities of nine peppers

The contents of bioactive compounds (Vitamin C (Vc), carotenoids, total phenolics, phenolic profiles and capsaicinoids) and antioxidant activities (reducing power, DPPH-scavenging activity and lipid peroxidation inhibition ability) of nine peppers from Yunnan province China, belonging to seven cultivars, were determined. Red and green Point pepper/Long-point pepper were from the same cultivars at different maturity stages. Results showed that all fresh pepper samples were rich in Vc, carotenoids, and total phenolics. Vc contents varied mainly depending on the pepper cultivars, except for the ripened stages. The phenolic content in red Fructus Capsici (Capsium frutescens L.) was significantly higher than that of others (Capsium annuum L.) (p < 0.05). Seven phenolics were identified in four pepper samples, while six phenolics were detected in other samples. The capsaicinoid contents of nine peppers showed a large variability, and the content in red Fructus Capsici was significantly higher than that of others (p < 0.05). The extracts of nine peppers showed high reducing power, DPPH-scavenging activity, and lipid peroxidation inhibition ability, and the activities of Fructus Capsici were significantly stronger than those of others (p < 0.05). Furthermore, antioxidant activities of nine peppers correlated well with their total phenolic contents.     

Differential effect of organic cultivation on the levels of phenolics,peroxidase and capsidiol in sweet peppers

BACKGROUND: Coincident with the changes in agricultural practices from conventional to organic, changes in the nutrient composition of fresh fruits and vegetables have been identified. The levels of peroxidase, total phenolics content, and capsidiol activity in organic as compared with conventional sweet pepper fruit were examined in this study. In order to avoid interferences of environmental factors on the studied parameters, the sweet peppers were grown (organically and conventionally) in a greenhouse under the same soil and climate conditions. RESULTS: Peroxidase was partially purified using the Triton X‐114 method and both organic and conventional peppers had the same isoenzymatic form. However, peroxidase activity in organic sweet peppers was higher than in conventional ones, in both maturity stages studied. The level of total phenolics compunds was also higher in organic than in conventional sweet peppers. With respect to the capsidiol activity, expressed as inhibition of fungus growth, it was not affected by the cultivation method at the green mature stage. However, at the red mature stage, organic sweet peppers showed higher capsidiol activity than those grown under the conventional system. CONCLUSION: Sweet peppers grown under organic culture have a maturity‐related response, with high levels of phenolic compounds, and peroxidase and capsidiol activity that contribute to disease resistance in organic farming. Copyright © 2007 Society of Chemical Industry     

不同品种紫肉甘薯抗氧化能力及花色苷成分分析

以广东地区9?个不同品种的紫肉甘薯为研究对象,评价紫肉甘薯抗氧化能力,并对花色苷的组成进行定性和定量分析。结果表明：不同品种紫肉甘薯,总酚含量和抗氧化能力也不尽相同,其中广紫9的总酚含量为578?mg?GAE/100?g,清除2,2’-联氮基-双-（3-乙基苯并噻唑啉-6-磺酸）二铵盐（2,2’-amino-di (3-ethyl-benzothiazoline sulphonic acid-6) ammonium salt,ABTS）自由基能力、氧自由基吸收能力、还原能力分别为4.36、10.38、11.23?μmol?TE/g,均高于其他品种的紫肉甘薯。通过高效液相色谱-四极杆飞行时间质谱法共鉴定出16?种花色苷,包括8?种矢车菊素类和8?种芍药素类。紫肉甘薯花色苷含量在77.17～1?125.06?mg/kg之间,以广紫9含量最高,花色苷主要以酰基化的形式存在,其含量是非酰化的89?倍,酰基化程度明显高于其他品种。综上所述,不同品种紫肉甘薯具有不同的抗氧化能力,其花色苷含量与结构也有较大差异,其中广紫9花色苷含量最高,抗氧化能力最强。     

Changes in the contents of antioxidant compounds in pepper fruits at different ripening stages,as affected by salinity

The interest in the consumption of pepper fruits (Capsicum annuum L.) is, to a large extent, due to its content of bioactive nutrients and their importance as dietary antioxidants. A greenhouse experiment was carried out to determine the effects of salinity and different ripening states of pepper fruits on several compounds with antioxidant properties. Fruits from plants grown under three saline treatments (0, 15, and 30 mM NaCl) were collected at three maturity states (green, turning, and red). Antioxidant activity in the hydrophilic (HAA) and lipophilic (LAA) fractions, lycopene, β-carotene, ascorbic acid, total phenolic compounds and reducing sugars were determined. From the nutritional point of view, the red state was the most appropriate state of maturation, since red peppers had the highest levels of lycopene, β-carotene, and sugars and the highest antioxidant activity for both hydrophilic and lipophilic fractions. The effect of salinity depended on the maturity state of the peppers: it had no effect on HAA, β-carotene or sugars, but decreased ascorbic acid and total phenolic compounds, and increased LAA and lycopene. The use of a moderately-saline water was beneficial when peppers were harvested in the red state, by increasing HAA and LAA in fruits, with no significant effects on other parameters.     

Antioxidant Properties and Rutin Content of High Pressure-Treated Raw and Roasted Buckwheat Groats

The effect of high hydrostatic pressure treatment (200 MPa for 2, 4, and 9 min) on the total antioxidant capacity (TAC), reducing capacity (TRC), and rutin content of raw and roasted buckwheat groats was studied by an updated analytical strategy. TAC and TRC were calculated as the overall capacity of hydrophilic and lipophilic antioxidants. Antioxidant capacity was measured against the 2,2′-azinobis-(3-ethylbenzothiazoline-6-sulfonate) radical cation (ABTS^?+) and the 2,2-diphenyl-1-picrylhydrazyl radical (DPPH^?), and by the photo-induced chemiluminescence assay against the superoxide anion radical (O ₂ ^?? ), whereas the reducing capacity was evaluated with the Folin-Ciocalteu reagent (FCR) and directly by the cyclic voltammetry method. Rutin content was determined by HPLC analysis. The TAC of pressure-treated raw and roasted groats was 16–20% and 12.5–17% lower in comparison with untreated groats, respectively. Hydrophilic antioxidants were the main contributor to the TAC of pressure-treated raw and roasted groats. High pressure treatment of raw groats lowered the FCR reducing capacity of hydrophilic antioxidants by an average of 12.6% and 12%, respectively. In contrast, the pressurization of roasted groats increased radical scavenging capacity by 18% on average due to the presence of hydrophilic compounds in roasted groats. The variations in the antioxidant properties of pressure-treated raw groats were accompanied by an average 47% drop in rutin content, whereas irregular changes were noted in HP-treated and roasted material.     

Antioxidant compound contents and antioxidant activity before and after cooking in sweet and bitter Chenopodium quinoa seeds

The antioxidant activity and the relationship between total antioxidant activity and the main classes of antioxidants in the seeds of bitter and sweet Chenopodium quinoa seeds were measured before and after boiling, in order to establish which one showed the best antioxidant property and how a traditional cooking method could affect it. Our results, obtained by using DPPH (1,1-diphenyl-2-picrilhydrazyl) and FRAP (Ferric Reducing/Antioxidant Power) methods, showed that antioxidant activity of bitter seeds was higher than that of sweet seeds. This activity principally depended on phenols and flavonoids in bitter seeds, while it was mainly due to phenol, flavonoid and carotenoid compounds in sweet seeds. Moreover, boiling caused a significant loss of antioxidant capacity in water.     

Using mild heat treatment to improve the bioactive related compounds on fresh-cut green bell peppers

Bioactive related compounds of fresh-cut green bell peppers ( Capsicum annuum, L.) exposed to water immersion at 55 °C and 60 °C per 180 s were evaluated during storage. Their sensorial and microbial quality, acidity, sugar and chlorophyll content were also determined. Beneficial effects on sensorial attributes were observed in treated peppers with longer shelf life than in non-treated ones (5 days at 4 °C, 2 days at 10 °C). At the end of storage at 4 °C, phenols increased to 11% and quercetin and antioxidant capacity were retained, but in control peppers ascorbic acid dropped 16%. At 10 °C, there was no change in phenols; quercetin, ascorbic acid and antioxidant activity decreased (15%, 13% and 10% respectively) in treated peppers. Changes were more noticeable in non-treated products (phenols increased 21%, ascorbic acid decreased 28% and antioxidant activity 20%). Mild heat treatments applied to fresh-cut peppers seemed to preserve some of their bioactive compounds during storage.     

低温真空膨化与自然干制对红枣抗氧化活性的影响

目的：研究低温真空膨化和自然干制对红枣抗氧化成分及活性的影响,为生产加工优质枣产品和低温真空膨化技术在红枣加工方面应用提供科学依据。方法：以矮化密植枣树所得枣果为材料,采用Folin-Ciocalteu与NaNO2-Al(NO3)3法测定总酚、总黄酮含量;通过DPPH自由基清除率、ABTS+•清除能力、总还原力和抗亚油酸过氧化能力等指标表征枣果抗氧化能力;采用高效液相色谱法对酚类化合物进行定性定量分析。结果：红枣经膨化后总酚含量显著增加,而总黄酮未发生明显变化,自然干制使总酚、总黄酮含量显著降低。膨化枣DPPH自由基清除能力和总还原力显著优于鲜枣和自然干制枣,自然干制处理使红枣ABTS+•清除能力和β-胡萝卜-亚油酸抗氧化活性显著低于膨化枣与鲜枣。膨化枣中总酚、总黄酮和抗氧化能力显著高于自然干制枣。干制处理使枣果中酚类化合物组成发生明显变化,膨化枣中没食子酸、对羟基苯甲酸、咖啡酸、对香豆酸、阿魏酸、芦丁、肉桂酸和槲皮素的含量最高。相关性研究表明鲜枣与干制枣中抗氧化活性与总酚、总黄酮显著相关。结论：低温真空膨化枣含有丰富的酚类化合物与最高抗氧化能力,且加工时间短,口感酥脆香甜。综上所述,低温真空膨化技术可作为一种可用于规模化干制枣的现代化加工技术。     

Effect of cooking on the antioxidant properties of coloured peppers

Pepper (Capsicum annum L.) has long been recognized as an excellent source of antioxidants, being rich in ascorbic acid and other phytochemicals. This study was conducted to investigate the effect of different cooking methods on the antioxidant properties of coloured peppers. Six varieties of peppers were subjected to different cooking methods, such as microwave heating, stir-frying and boiling in water, for 5 min individually. The cooked and raw peppers were analyzed for radical-scavenging activity (RSA) and total polyphenol content (TP) using 1,1-diphenyl-2-picrylhydrazyl–high-pressure liquid chromatography (DPPH)–HPLC and Folin-Ciocalteu methods, respectively. The samples were also evaluated for ascorbic acid content (AsA) by HPLC. Total carotenoid content was determined spectrophotometrically. Results suggest that there is no significant (P > 0.05) difference in RSA, TP, AsA and total carotenoid contents between the cooked and raw peppers when processed for 5 min. However, the cooked peppers show marked differences (P < 0.05) in the RSA, TP and AsA when cooked for 5 min in boiling water with further reduction observed after boiling for 30 min. This may be due to the leaching of antioxidant compounds from the pepper into the cooking water during the prolonged exposure to water and heat. Therefore, it is vital to use less water and cooking time and also to consume the water used for boiling so as to obtain the optimum benefits of bioactive compounds present in peppers. It is concluded that microwave heating and stir-frying without using water are more suitable cooking methods for pepper, to ensure the maximum retention of antioxidant molecules.     

Variation of antioxidant activity and the levels of bioactive compounds in lipophilic and hydrophilic extracts from hot pepper (Capsicum spp.) cultivars

Peppers (Capsicum spp.) are a rich source of diverse bioactive compounds with potential health-promoting properties. This study investigated the extraction efficiency of five solvents on antioxidant activities from cayenne (CA408 and Mesilla), jalapeño (Ixtapa) and serrano (Tuxtlas) pepper cultivars. Freeze-dried peppers were extracted using a Soxhlet extractor with five solvents: hexane, ethyl acetate, acetone, methanol, and methanol:water (80:20). The levels of specific bioactive compounds (phenolics, capsaicinoids, carotenoids and flavonoids) were determined by HPLC and antioxidant activities were assayed by three methods. For all pepper cultivars tested, hexane extracts had the highest levels of capsaicinoids and carotenoids, but methanol extracts had the maximum levels of flavonoids. Hexane extracts showed higher 2,2-diphenyl-1-pricrylhydrozyl (DPPH) radical-scavenging activity and higher reducing power, and acetone extracts (from Mesilla pepper) had a high reducing power. All pepper extracts, except hexane, were effective in preventing deoxyribose degradation, and the inhibition was increased by high concentrations of extracts. The results of the present study indicated that, among the different measures of antioxidant activity, DPPH radical-scavenging activity was strongly correlated with total bioactive compounds (capsaicinoids, carotenoids, flavonoids and total phenolics) in pepper cultivars.     

Quantification of the polyphenolic fraction and in vitro antioxidant and in vivo anti-hyperlipemic activities of Hibiscus sabdariffa aqueous extract

In the present study the quantification of the polyphenolic fraction, anthocyanins and other polar compounds, the antioxidant capacity and the anti-hyperlipemic action of the aqueous extract of Hibiscus sabdariffa has been achieved. Seventeen compounds were successfully quantified either by HPLC-DAD or HPLC-ESI-TOF-MS. Six of them were directly quantified by their corresponding standards, whereas the rest were indirectly quantified as equivalents using standards of similar compounds. The antioxidant capacity have also been estimated by comparing different assays, i,e, Trolox equivalent antioxidant capacity (TEAC), ferric reducing antioxidant power (FRAP), oxygen radical absorbance capacity (ORAC), and measurement of thiobarbituric acid reacting substances (TBARS). H. sabdariffa showed high reducing capacity in FRAP assay and significant capability to scavenge peroxyl radicals in the ORAC assay. Nevertheless, the extract exhibited poor efficacy to inhibit peroxyl radicals in lipid systems. The plant extract also exhibited the capacity to decrease serum triglyceride concentration on hyperlipemic mouse model.     

Effect of Domestic Cooking Methods on Antioxidant Capacity of Fresh and Frozen Kale

The aim of this study was to evaluate the changes in the antioxidant capacity of fresh and frozen kale during domestic cooking methods (e.g., boiling, microwaving, and steaming). The antioxidant activities of the samples were measured using three in vitro assays (1,1-diphenyl-2-picrylhydrazyl assay, 2, 2’-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid assay, and ferric reducing antioxidant power assay). The steaming treatment was found to be the best cooking method to retain antioxidant compounds, followed by the microwaving and boiling treatments. The frozen uncooked samples exhibited a higher antioxidant capacity than the fresh, uncooked samples, indicating that the freezing process could enhance the antioxidant capacity of the kale.