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.     

Influence of Ca2+, K+ and NO3− fertilisation on nutritional quality of pepper

A study was conducted in order to assess the effect of different fertilisation levels of Ca²⁺, K⁺ and NO₃^? on the bioactive nutrient content in red pepper (Capsicum annuum L) fruits. The experiment was carried out in a greenhouse, under hydroponic culture. Lycopene, β‐carotene, vitamin C, total phenolic compound, sugar, nitrate and potassium contents and antioxidant activity were determined. Increasing Ca²⁺ and NO₃^? concentrations in the root medium increased the lycopene and β‐carotene contents in pepper. Antioxidant activity was determined in the hydrophilic (HAA) and lipophilic (LAA) fractions. HAA was increased by intermediate and high Ca²⁺ concentrations in the culture medium. However, LAA was raised only by NO₃^? treatments. Vitamin C, sugar and total phenolic acid contents were not affected by Ca²⁺ or NO₃^? treatments. K⁺ treatments had no effect on nutritional quality of pepper. An increased supply of Ca²⁺ and NO₃^? in the culture medium could constitute a useful practice for improving the nutritional attributes of pepper as well as its commercial quality. Copyright © 2004 Society of Chemical Industry     

Hydrophilic and lipophilic antioxidant activities of grapes

The 2,2'-azino-bis-(3-ethylbenzthiazoline-6-sulfonic acid)/H2O2/horseradish peroxidase (ABTS/H2O2/HRP) decoloration method permits the evaluation of the antioxidant activity of complex food samples. This method is capable of determining both hydrophilic (in buffered media) and lipophilic (in organic media) antioxidant properties in the same sample. Its application to the study of the antioxidant properties of grapes, one white and two black, has permitted us to establish important differences in the antioxidant activity. The black grapes showed higher antioxidant activity than the white variety. The determination of hydrophilic antioxidant activity (HAA) and lipophilic antioxidant activity (LAA) in the three grapes showed that a minor contribution (4-13%) of total antioxidant activity (TAA) was due to LAA in all cases. The experimentally determined HAA could be approximated using the relative contributions of the calculated values of reference compounds (total phenols as gallic acid and anthocyanins as malvidin).     

Antioxidant compounds in green and red peppers as affected by irrigation frequency,salinity and nutrient solution composition

BACKGROUND: There is a need to encourage more sustainable agricultural practices, reducing inputs of water and fertilisers while minimising any negative impact on fruit quality. The effect of irrigation frequency, salinity and potassium and calcium fertilisation on the content of bioactive compounds and quality attributes of green and red peppers grown with and without substrate was evaluated. RESULTS: Low irrigation frequency and salinity improved the quality attributes (dry matter, soluble solids content and titratable acidity) of pepper. Low irrigation frequency increased vitamin C content by 23% in green peppers, while in red fruits it was not affected. In contrast, total carotenoids and provitamin A only increased in red fruits by 30% and 15%, respectively, as a consequence of low irrigation frequency. When the effect of potassium and calcium doses was investigated, it was shown that a high proportion of potassium increased the vitamin C, provitamin A and total phenolic content of red and green peppers, whereas pepper grown at low calcium doses, presented the highest content in carotenoids and provitamin A. CONCLUSION: Low irrigation frequency and fertilisation with high potassium and low calcium doses improved pepper quality increasing the content of bioactive compounds. Copyright © 2009 Society of Chemical Industry     

Effect of natural biostimulants on yield and nutritional quality: an example of sweet yellow pepper (Capsicum annuum L.) plants

BACKGROUND: Modifications in growing techniques can affect the yield and nutritional quality of various cultivated plant species. Owing to its high nutritional value, pepper (Capsicum annuum L.) was used in this study as a model plant to investigate the effect of natural biostimulants on yield and fruit quality parameters under conditions of reduced fertilisation. RESULTS: A positive influence of biostimulant treatment on yield parameters was observed. The overall increase in the pigment content of leaves after biostimulant application agreed well with the higher total and commercial yields of treated pepper cultivars compared with their controls. The results showed that natural biostimulants had a positive effect on the vitamin C and total phenolic contents in pepper fruits during the hot summer season. The 1,1‐diphenyl‐2‐picrylhydrazyl (DPPH) and 2,2′‐azinobis(3‐ethylbenzothiazoline‐6‐sulfonate) (ABTS) antioxidant activities were also significantly higher (P < 0.05) in treated plants and correlated strongly with all measured quality parameters except total phenolic content. CONCLUSION: Generally, biostimulants improved the antioxidant activity, vitamin C and phenolic contents in fruits as well as the pigment content in leaves of treated compared with non‐treated pepper plants grown hydroponically. Thus the application of biostimulants could be considered as a good production strategy for obtaining high yields of nutritionally valuable vegetables with lower impact on the environment. Copyright © 2011 Society of Chemical Industry     

Sustainable nitrogen fertilisation in sweet pepper: assessing growth and fruit quality and the potential nitrate pollution from different organic manures

BACKGROUND: The use of organic cultivation with manures does not avoid the risk of high nitrate concentrations if nutrient management is inefficient. So we studied the influence of three organic manures combined or not with additional chemical fertilisers on growth and yield of sweet pepper (Capsicum annuum L.), and on the soil and plant N concentrations. RESULTS: After 3 years of organic cultivation, poultry manure caused the highest soil pollution. The evolution of nitrate and organic matter in soil showed a pattern close to that of plant growth. The addition of mineral fertiliser increased vegetative growth and yield, and a cumulative season effect was observed. In treatments with no additional mineral fertiliser N translocation from leaves to fruits happened. A cumulative effect of seasons on fruit quality and a reduction near to 30% was observed in the first fruit quality category after 3 years. The fruit vitamin C content was reduced by increasing N fertilisation. CONCLUSION: The effects of organic fertiliser on soil and plant growth and yield depended on the type of manure used, its rate, and consecutive crop seasons. Horse manure gave the best combination of agricultural and environmental characteristics and could be used without additional fertigation. © 2012 Society of Chemical Industry     

Characterisation of antioxidant compounds in sweet bell pepper (Capsicum annuum L.) under organic and conventional growing systems

BACKGROUND: Sweet red bell pepper is one of the best sources of ascorbic acid and carotenoids as well as phenolic compounds important in the human diet. There have been some studies showing a higher level of bioactive compounds in organic bell pepper fruits compared with conventional fruits, but not all studies have been consistent in this respect. The levels of carotenoids and phenolics are very variable and may be affected by ripeness, genotype and cultivation. RESULTS: The results obtained in this study showed that an organic growing system affected the level of bioactive compounds (carotenoids and polyphenols) in sweet bell pepper fruits cultivated in Poland. Organic bell pepper fruits contained significantly more dry matter, vitamin C, total carotenoids, β‐carotene, α‐carotene, cis‐β‐carotene, total phenolic acids (as well as individual gallic and chlorogenic acids) and flavonoids (quercetin D ‐glucoside, quercetin and kaempferol) compared with conventional fruits. The bell pepper variety also affected the level of antioxidant compounds in fruits. CONCLUSION: Organic growing increased the level of antioxidant compounds such as carotenoids, phenolic compounds and vitamin C in sweet bell pepper. The second significant factor affecting the antioxidant compound content of sweet bell pepper was variety. It would be necessary to continue this study as a long‐term experiment in order to eliminate the influence of seasonality. Copyright © 2012 Society of Chemical Industry     

Antioxidant capacities and total phenolic contents of 56 vegetables

The antioxidant capacities and total phenolic contents of lipophilic and hydrophilic extracts of 56 commonly consumed vegetables were studied. The resulted showed that antioxidant capacities and total phenolic contents in the lipophilic fraction were higher than those in hydrophilic fraction. The different vegetables had diverse antioxidant capacities. The highest antioxidant capacities and phenolic contents were found in Chinese toon bud, loosestrife, perilla leaf, cowpea, caraway, lotus root, sweet potato leaf, soy bean (green), pepper leaf, ginseng leaf, chives, and broccoli, while the values were very low in marrow squash and eggplant (purple). Furthermore, several phenolic compounds were detected, and chlorogenic acid, gallic acid and galangin were widely found in these vegetables. The results provide support for dietary guidelines as well as epidemiological research.     

Pepper antioxidant composition as affected by organic,low‐input and soilless cultivation

BACKGROUND: The aim of this work was to study the effects of organic (O), low‐input (LI) and soilless (SL) cultivation on pepper nutritional quality and antioxidant activity. For that, 24 commercial greenhouses were selected following strict criteria in order to reduce the influence of environmental conditions and realistically reflect commercial production systems. Fruits were harvested at two maturity stages (green and red) and three harvesting times during two consecutive years. RESULTS: Pepper antioxidant activity mainly stemmed from water‐soluble compounds, including organic acids and phenolic compounds. Only some differences in sugars and malic and citric acid concentrations were detected between the O and LI systems. Sugars, phenolic compounds, ascorbic acid and hydrophilic antioxidant activity were higher in the SL system. In spite of these differences, overall differences between harvesting times or between years were far greater than those due to the cropping system. CONCLUSION: The main differences in the nutritional quality of pepper fruits were observed between the soil (O and LI) and SL (the most favourable) systems. The results highlight the importance of comparing different harvesting times and years in order to study the effect of cropping system on a specific crop. Copyright © 2009 Society of Chemical Industry     

不同品种枣果实发育过程中多酚类物质、VC含量的变化及其抗氧化活性

为探索不同品种枣果发育过程中多酚类物质与抗氧化活性的动态变化规律,对灰枣、鸡心枣、梨枣、赞皇枣、磨盘枣、葫芦枣6 个枣品种的不同发育期果实中多酚类物质的含量及组成和VC含量及抗氧化活性进行分析测定。结果表明,供试各品种枣果实中总酚、总黄酮、VC含量和抗氧化活性均在采摘初期（幼果期）为最高,其后随着果实的发育呈逐渐下降趋势。其中总酚、总黄酮含量在绿熟期前下降迅速,绿熟期以后变化趋缓,果实接近成熟时则趋于平稳,全红期果实可较采摘初期降低60%以上;VC含量和抗氧化活性在白熟期前下降较快,白熟期后降幅变小。高效液相色谱（high performance liquid chromatography,HPLC）分析结果显示,儿茶素、表儿茶素、芦丁是供试各品种枣果实中最主要的酚类物质,这些酚类物质含量在枣果实发育过程中也呈下降趋势,但在不同品种间存在较大差异。供试枣果实抗氧化活性与其中的总酚、总黄酮、VC以及儿茶素、表儿茶素、芦丁等主要酚类物质的含量均存在极显著相关关系（P＜0.01）,其中尤以芦丁、表儿茶素、儿茶素与抗氧化活性的相关性较高,说明芦丁、表儿茶素、儿茶素等多酚类物质是枣果中最主要的抗氧化活性成分。磨盘枣、葫芦枣具有较高的多酚类物质含量和抗氧化活性,鸡心枣具有较高的VC含量,是功能性枣果及其加工制品生产的理想品种。     

Cultivation approach for comparing the nutritional quality of two pepper cultivars grown under different agricultural regimes

The aim of this study was to assess the influence of the cropping system (organic or conventional) and the growth medium (soil or soilless) on the antioxidant content of peppers from Almuden and Quito cultivars. This cultivation study complements a previous farm study. For both cultivars, organic cultivation led to higher fruit lipophilic antioxidant content than conventional management but differences in the hydrophilic fraction were not observed. The effect of the growth medium on pepper composition depended on the studied cultivar. In Almuden, neither the hydrophilic nor the lipophilic fractions were affected by the growth medium, while in Quito most compounds showed higher values in soil-grown plants. Taking into account the results from the present and the previous farm study we conclude that the effect of organic vs. conventional cultivation on pepper quality can be attributed to the different nutritional regimes and other factors associated with the agricultural system. However, both aspects are not necessarily different in organic and conventional commercial crops. The effect of the growth medium (soil or soilless) on pepper quality depended on the cultivar: Almuden was not affected by the growth medium and Quito was seen to be less suitable for soilless cultivation.     

Potential of nanofiltration for the concentration of bioactive compounds from watermelon juice

The aim of this study was to evaluate the potential of nanofiltration for the concentration of bioactive compounds of watermelon juice. Lipophilic and hydrophilic antioxidant activities were determined through two assays, ferric reducing antioxidant power and DPPH. The content of lycopene, flavonoids and total phenolic in the concentrate samples increased with the increase in the volume reduction factor. Volume reduction factor of three showed the best performance of concentration, generating the highest values for lycopene, flavonoid and total phenolic contents. Average permeation flux was 2.3 L h^?1 m^?2, with continuous extraction of the concentrate at a volumetric reduction ratio of three. Lycopene showed the highest rejection coefficient (0.99), followed by flavonoids (0.96) and total phenolic content (0.65). The hydrophilic antioxidant activity values in both assays were higher than the lipophilic antioxidant activity values. A highly significant correlation was noted between the contents of flavonoids, phenolic compounds, ascorbic acid, and lycopene and their antioxidant potential in both lipophilic and hydrophilic fractions.     

Antioxidant and nutritive constituents during sweet pepper development and ripening are enhanced by nitrophenolate treatments

A mix of nitrophenolates was applied to pepper plants in the irrigation system along the growth cycle. Fruits were labelled at fruit set to study the evolution of fruit growth and ripening based on fruit size and colour. In addition, at 3-day intervals, samples were taken in which the evolution of fruit weight, colour, nutritive (sugars and organic acids) and bioactive compounds (total phenolics, carotenoids, and ascorbic acid) was evaluated. Pepper fruit growth followed a simple sigmoid curve reaching its maximum size at 49 days after fruit set, although nitrophenolate treatments led to significant increases in fruit weight due to higher length, diameter, and pericarp thickness, without affecting the normal ripening process, since colour and carotenoid evolution was similar for both control and treated fruits. Glucose, fructose, ascorbic acid, citric acid, total antioxidant activity (TAA) and total phenolics increased during pepper development, and their levels were significantly enhanced by nitrophenolate applications. Thus, this treatment induced beneficial effects in terms of the improvement of fruit quality, and especially its nutritive and antioxidant constituents. Finally, it is advisable to consume peppers at the full red stage in order to achieve the maximum health-beneficial effects by consumers.     

Vitamin C,vitamin A,phenolic compounds and total antioxidant capacity of new fruit juice and skim milk mixture beverages marketed in Spain

The growing interest in new functional foods with special characteristics and health properties has led to the development of new beverages based on fruit juice–skim milk mixtures. The proliferation of ready-to-drink beverages has caused the market to focus its interest on these products. Commercial conventionally pasteurized or sterilized beverages based on a mixture of fruit juice and skim milk were evaluated nutritionally for their concentrations of vitamin C, vitamin A and phenolic compounds and their total antioxidant capacity, taking the influence of physicochemical parameters into account. The main contribution to the total antioxidant capacity (TEAC, trolox equivalent antioxidant capacity) was provided by vitamin C, followed by phenolic compounds, in accordance with a mathematical equation obtained from the data: TEAC = −0.184 + 0.009 ∗ [vitamin A] + 0.011 ∗ [phenolic compounds] + 0.058 ∗ [vitamin C]. The R-squared value was 86.88%. Citrus fruits, such as lemons or oranges, were the fruits associated with the greatest antioxidant capacity in the samples analysed.     

Effect of different light transmittance paper bags on fruit quality and antioxidant capacity in loquat

BACKGROUND: Bagging has been widely used to improve the commercial value of fruit. The purpose of this study was to evaluate the effects of different light transmittance paper bags on the quality and antioxidant capacity of loquat fruit. Two loquat cultivars, Baiyu and Ninghaibai (Eriobotrya japonica Lindl.), were used for materials. One‐layered white paper bags (OWPB) with ～50% light transmittance and two‐layered paper bags with a black inner layer and a grey outer layer (TGDPB) with ～0% light transmittance were used as treatments and unbagged fruits were used as the control (CK) in this experiment. Fruit quality was determined by physicochemical characteristics, the quantity of sugar, total phenolic, flavonoid, carotenoid and vitamin C. The antioxidant capacities of the methanol extracted from the pulp were tested using three different assays. RESULTS: The results showed that bagging decreased the weight of fruit but promoted the appearance of loquat fruits. The total sugar content in the fruit bagged with OWPB was higher than in controls and in fruit bagged with TGDPB. The total phenolic and flavonoid contents were decreased by both bagging treatments, with the lowest occurring in the fruit bagged with TGDPB. Bagging also decreased the total antioxidant capacity of the fruit pulp, which was again lower in TGDPB‐treated fruits than in those bagged using OWPB. Correlation analysis showed a linear relationship between total antioxidant capacity and the content of total phenolic and flavonoid. CONCLUSION: The results showed that different light transmittance bags had different effects on fruit quality and antioxidant capacity. In particular, bags with low light transmittance (TGDPB) decreased the inner quality and total antioxidant capacity of loquat fruit. All results indicated that bagging with OWPB was more suitable for maintaining the quality of the loquat fruit than bagging with TGDPB. Copyright © 2010 Society of Chemical Industry     

EFFECTS OF VARIETY AND GROWTH SEASON ON THE ORGANOLEPTIC AND NUTRITIONAL QUALITY OF HYDROPONICALLY GROWN TOMATO

The effects of variety and season on several organoleptic and nutritional quality parameters (i.e., dry weight (dw), total sugars, soluble solid compounds, titratable acidity (TA), electrical conductivity (EC), juiciness, firmness, vitamin C (vit C), total phenolic compounds, hydrophilic antioxidant capacity and minerals) of five different varieties of tomatoes (i.e., Jack, Cabrales, Jaguar, Iker and Nevada) grown in two crop cycles (spring and autumn) were studied. Each variety presented its own specific characteristics regarding the chosen parameters. Firmness, TA and EC were season dependent, whereas soluble solids content did not change between cycles. In some varieties, the dw, juiciness and total sugars were affected by climatic conditions. The total phenolic compounds and the hydrophilic antioxidant capacity were variety dependent in both cycles. By contrast, the vit C content was variety dependent only in the autumn cycle. Similarly, these latter parameters (phenolic compounds, hydrophilic antioxidant capacity and vit C) were also season dependent, showing higher values in the spring than in the autumn cycle. The effect of tomato variety and season on mineral contents is also discussed. Those tomatoes grown in the spring cycle had better quality according to the organoleptic parameters studied here as well as to a higher antioxidant capacity. The percentages of the recommended dietary allowances supplied by the studied tomatoes were not significantly affected by variety or season, despite differences in their physicochemical compositions.     

Phytochemical and antioxidant characterization of the fruit of black sapote (Diospyros digyna Jacq.)

Consumption of fruits and vegetables has been associated with a healthy state which has been attributed, in part, to their antioxidant capacity. Characterization of the bioactive compounds with antioxidant activity found in fruits cultivated in the tropic is limited. Thus, the objective of the present work was the characterization of phytochemicals and antioxidants of the fruit of black sapote (Diospyros digyna Jacq.). HPLC-DAD-Mass Spectrometry (HPLC-MS) analyses were used to identify and quantify phenolics, carotenoids and tocopherols. Total soluble phenolic content was 247.8 mg GAE/100 g fw (fresh weight). Important phenolics identified were sinapic acid, myricetin, ferulic acid, and catechin. Total carotenoid content was 399.4 ??g of ??-carotene/100 g fw, and ??-carotene and lutein were the main carotenoids identified. ??-Tocopherol concentration was 672.0 ??g/100 g dry weight. Antioxidant capacity as measured by the DPPH and FRAP assays was higher in the hydrophilic than in the lipophilic extract, and it is thought to be due mainly to the phenolic content of this fruit. Results suggest that the fruit of black sapote has an antioxidant capacity comparable to other important fruits, and its inclusion in the diet is therefore recommended.     

In vitro bioaccessibility of health-related compounds as affected by the formulation of fruit juice- and milk-based beverages

The purpose of this research was to evaluate the influence of the beverage formulation on the in vitro digestibility and bioaccessibility of phenolic compounds, vitamin C, and carotenoids, as well as antioxidant activity from milk, a blended fruit juice (BFJ) and a combination of both of them (BFJ–MB). The release of many phenolic substances was improved during gastric digestion of milk and BFJ–MB (around 5 and 75%), but not in BFJ. Vitamin C and carotenoids diminished significantly (P < 0.05) in the gastric and intestinal digesta of each beverage. Phenolic acids, flavonoids, vitamin C and hydrophilic constituents with antioxidant activity were more bioaccessible in BFJ (up to 3.4 times) than in milk and BFJ–MB. On the contrary, the bioaccessibility of carotenes, xanthophylls and those compounds with lipophilic antioxidant activity was improved when milk was added to BFJ (up to 1.9 times). Results suggest that the addition of milk improved the bioaccessibility of lipophilic constituents but not that of hydrophilics. Nevertheless, BFJ–MB combines the nutritional ingredients of milk and BFJ. As a result, BFJ–MB could supply a higher diversity of bioaccessible compounds in comparison to that of milk and BFJ alone, promoting health and protecting against several diseases.     

Effect of maturity stage on the content of fatty acids and antioxidant activity of ‘Hass’ avocado

Avocado (Persea americana) is an important tropical fruit and a good source of lipophilic phytochemicals such as monounsaturated fatty acids, carotenoids, vitamin E and sterols that have been inversely related to cardiovascular diseases. However, their antioxidant capacities have received far less attention compared with hydrophilic phytochemicals in this fruit. In this context, this study evaluated the effect of the stage of ripeness of ‘Hass’ avocado on the content of lipophilic and hydrophilic phytochemicals and their correlation with the antioxidant capacity. In every ripeness stage the fatty acids, total phenolic and flavonoid content as well as the antioxidant capacity were evaluated. Physiological and physico-chemical analysis were also performed including respiration rate, ethylene production, firmness, color (L*, °Hue, and Chroma), dry matter and oil content. In general, total phenols increased during ripening, while flavonoids slightly decreased. The main fatty acid identified was oleic acid (about 67-70% of total content). In general, a significant increase in monounsaturated and saturated fatty acids was observed during avocado ripening while polyunsaturated fatty acid content decreased (p < 0.05). Lipophilic extracts showed higher values of antioxidant capacity than hydrophilic, however, both extracts had similar trends for DPPH, TEAC and ORAC assays. DPPH and TEAC assays had a positive correlation with some unsaturated fatty acids. Avocado at different ripeness stages showed a better antioxidant capacity in the lipophilic fraction, which correlated with the fatty acid content evaluated.