Effect of semi-drying on the antioxidant components of tomatoes

Three tomato cultivars (Excell, Tradiro, and Flavourine) grown under hydroponic conditions in a commercial greenhouse in New Zealand were semi-dried at 42 °C. The semi-dried tomatoes contained low levels of 5-hydroxymethyl-2-furfural and were significantly (p < 0.05) darker (lower CIELAB L* values) and had a higher mean a*/b* value (1.6) than the fresh tomatoes (1.2). The mean total phenolics in the semi-dried samples of tomatoes (300 mg gallic acid equivalents, GAE/100 g dry matter (DM)) was significantly lower than that of fresh tomatoes (404 mg GAE/100 g DM). The mean total flavonoid, and lycopene contents in the fresh samples (206 mg rutin equivalents/100 g DM, 63 mg/100 g DM, respectively) also showed a significant decrease after semi-drying (179 mg rutin equivalents/100 g, 54 mg/100 g DM, respectively). Ascorbic acid content in fresh tomatoes (284 mg/100 g DM) decreased to 223 mg/100 g DM after drying. The total antioxidant activity of the semi-dried tomatoes (1783 μmole trolox equivalents antioxidant capacity (TEAC)/100 g DM) was significantly (p < 0.05) lower than that of the fresh samples (2730 μmole TEAC/100 g DM).     

The antioxidant properties of whey permeate treated fresh-cut tomatoes

The aim of this research was to analyse the effects of three types of cheese whey permeate treatment on the antioxidant properties of fresh-cut tomatoes. Tomatoes were treated with whey permeate concentrate (PC), delactosed permeate (DP) and delactosed concentrate (DC), stored at 4 °C for 10 days and compared to samples treated with the industry standard, chlorine (120 ppm). Samples treated with DP retained significantly higher antioxidant activity (FRAP) and total phenols (TP), when compared with those treated with PC and DC. DP showed significantly higher results than chlorine for DPPH, FRAP and TP. In DPPH assay, all whey permeate-treated samples showed similar antioxidant activity, while ascorbic acid and lycopene were unaffected by treatment. Among the three whey permeates, delactosed permeate showed the best results in maintaining the antioxidant properties of tomato, suggesting it could be used to enhance the antioxidant activity of fresh-cut tomato and retain the antioxidant components during storage.     

Changes in post-harvest phytochemical qualities of broccoli florets during ambient and refrigerated storage

The effect of ambient and refrigerated storage temperature on post-harvest phytochemical qualities of broccoli florets was investigated during storage. Fresh broccoli florets were packed in polypropylene (PP) micro-perforated film bags and stored, under open ambient storage conditions (15 ± 1 °C, 55 ± 2% RH), and laboratory refrigerated storage (4 ± 0.5 °C, 50 ± 2% RH) for a total period of 144 h. Quality of broccoli florets was evaluated in terms of physiological weight loss (PLW), ascorbic acid content, chlorophyll content, β-carotene and total antioxidant activity. Samples packed in PP micro-perforated film showed significantly (P < 0.05) lower losses of PLW, ascorbic acid, chlorophyll, β-carotene and total antioxidant activity (5.51%, 4.53%, 18.9%, 4.04% and 16.4%, respectively), during storage for up to 144 h under refrigerated conditions. For better phytochemical retention, the broccoli florets should be packed in PP micro-perforated film bags and stored under refrigerated conditions.     

Effects of UV-C,red light and sun light on the carotenoid content and physical qualities of tomatoes during post-harvest storage

Mature-green (breaker-stage) tomatoes were harvested and treated daily with short bursts of UV-C, red light or sun light for up to 21 days. Control untreated tomatoes were kept in the dark for the same period. The effects of the treatments on the levels of the major tomato carotenoids, skin colour, tissue firmness and total soluble refractive solids were evaluated throughout storage. Results indicated that the concentration of lycopene in tomato exocarp was significantly increased after 4 days and dramatically enhanced by UV-C or red light treatments. However, the concentration of β-carotene was not affected by UV-C or red light treatments, and decreased by sun light treatment during 21 days of storage, compared to the control samples. The colour (a∗ and b∗ values) and force required to penetrate the tomatoes was, to a small but significant extent, influenced by the light treatments. However, the total soluble refractive solids of all tomato samples remained the same throughout storage. The findings reported here could be employed to improve tomato nutritional qualities lycopene content without inducing significant changes to the physical properties of tomatoes during post-harvest storage.     

Changes in bioactive compounds and antioxidant capacity of fresh-cut cashew apple

In this study, ascorbic acid, total polyphenols and proanthocyanidins of fresh-cut cashew apple were quantified. Antioxidant capacity was determined in whole juice and in polyphenols extracts by three methods: 2,2-diphenyl-1-picrylhydrazyl (DPPH), ferric reducing antioxidant power (FRAP) and ??-carotene bleaching. Effect of cutting and storage for 24 h at 2 °C, 27 °C and 40 °C on these compounds were also evaluated. Cashew apple presented 163 mg of ascorbic acid per 100 g of fresh weight (FW). Soluble and hydrolysable polyphenols contents were 12.79 mg GAE/100 g FW and 18.53 mg GAE/100 g FW and proanthocyanidins were 9.27 mg/100 g FW. Antioxidant capacity of juice and polyphenols extract was high for DPPH method. Storage temperatures affected bioactive compounds on cut cashew apple. The content of ascorbic acid decreased in all temperatures. Proanthocyanidins were more sensitive to 40 °C than to other temperatures. The content of polyphenols and antioxidant capacity of juice by DPPH assay did not change. However, the reducing power was lower in samples kept at high temperatures. A strong positive correlation between ascorbic acid and FRAP (r = 0.99) and a negative correlation between DPPH and FRAP (r = − 0.79) were observed. No correlations were found between polyphenols and antioxidant capacity indicating the importance of phenolic composition in the extracts. The results confirm the importance of temperature and injury on the quality of cashew apple.     

Variation in antioxidant components of tomato during vine and post-harvest ripening

The variation in the antioxidant content (lycopene, β-carotene, ascorbic acid and total phenolics) was evaluated on two tomato genotypes during vine and post-harvest ripening. Tomatoes were sampled and analysed at seven ripening stages according to the colour value. The data indicate that ripening conditions affected both the antioxidant accumulation kinetics and the final content, which was higher in post-harvest-ripened fruits. In particular, lycopene mainly accumulated in the very last period of ripening and its content was not linearly related to colour changes. Antioxidant accumulation and other ripening indexes were not significantly different in the two tomato genotypes. © 1999 Society of Chemical Industry     

Bioactive Compounds and Antioxidant Activity of Tomato Cultivars

The bioactive compounds of 16 tomato cultivars, grown in the same field for 2 years (2003 and 2004) were investigated. Lycopene (5.7–26.3 mg kg^?1) was the predominant carotenoid, while β-carotene (2.1–11.2 mg kg^?1) and a small amount of lutein (0.02–0.49 mg kg^?1) were found in all tomato cultivars. Kagome 77, the richest source of total carotenoids and L-ascorbic acid, also showed the highest antioxidant activity. β-Carotene and lutein contents of tomatoes differed between 2 years statistically. Antioxidant activities of tomatoes were found between 48 and 118 μmol TEAC 100 g^?1. A significant correlation was only observed between L-ascorbic acid (2.2–13.8 mg 100 g^?1) and antioxidant activity using TEAC assay.     

Kinetic modelling of the degradation of quality of osmo-dehydrofrozen tomatoes during storage

Tomato slices were submitted to osmotic pretreatment in a high DE maltodextrin syrup and were subsequently frozen. The objective was to evaluate the quality stabilisation of the osmo-dehydrofrozen samples during their frozen storage over a wide temperature range from −5 to −20 °C. Colour change, total lycopene content and vitamin C (l-ascorbic acid) loss were kinetically studied, and their temperature dependence was modelled by the Arrhenius equation. Dehydrofrozen samples exhibited significantly improved stability, with the rates of colour change, total lycopene and l-ascorbic acid loss being reduced by up to 64% for osmotically pretreated tomatoes, compared to the untreated samples.     

Changes in phenolic composition and antioxidant activity of white wine during bottle storage: Accelerated browning test versus bottle storage

Polyphenol content, antioxidant activity, reducing power, colour and changes during storage over nine months in bottles and after accelerated browning were studied in selected Hellenic varietal white wines. The following phenolic compounds were identified in the wines: Caftaric, coutaric, fertaric, ferulic, caffeic, p-coumaric and gallic acids, (+)-catechin and (−)-epicatechin. The results showed that the contents of most of the phenols diminished with time, with the exception of caffeic, ferulic and p-coumaric acids. Antioxidant activity increased with storage whereas reducing power remained significantly unaffected. Accelerated browning did not significantly alter the concentrations of tartaric acid esters but it increased the concentrations of the hydroxycinnamic and gallic acids. (+)-Catechin concentration was not affected while (−)-epicatechin decreased. Antioxidant activity did not show any significant change but reducing power was reduced after the end of the browning test. As for the absorbance at 420 nm, it remained unchanged during storage, but it was significantly increased after accelerated browning.     

Total phenolics, flavonoids and antioxidant activity of tropical fruit pineapple

Pineapple has several beneficial properties including antioxidant activity. The fruit of pineapple was extracted with ethyl acetate, methanol and water. The phenolic content of the extracts was determined by Folin-Ciocalteu method and antioxidant activity was assayed through some in vitro models such as antioxidant capacity by phosphomolybdenum, ??-carotene-linoleate, and radical scavenging activity using ??,??-diphenyl-??-picrylhydrazyl (DPPH) method. The phenolic contents of the extracts as caffeic acid equivalents were found to be highest in methanol (51.1%) followed by ethyl acetate (13.8%) and water extract (2.6%). Antioxidant capacity of the extracts as equivalent to ascorbic acid (??mol/g of the extract) was in the order of methanol extract > ethyl acetate extract > water extract. In comparison with butylated hydroxyanisole (BHA), at 100 ppm of concentration, the antioxidant and free radical scavenging activities of the extracts assayed through ??-carotene-linoleate and DPPH method were also found to be highest with methanol extract followed by ethyl acetate and water extracts. The results indicated that the extent of antioxidant activity of the extract is in accordance with the amount of phenolics present in that extract and the pineapple fruit being rich in phenolics may provide a good source of antioxidant.     

Changes in physicochemical characteristics and volatile compounds of apricot (Prunus armeniaca L. cv. Bergeron) during storage and post-harvest maturation

The effects of storage and post-harvest maturation on the physicochemical characteristics and volatile constituents of Bergeron apricot were investigated during the 2007 season over two experiments. Fruits, harvested at two distinct stages of maturity, in two different experimental orchards, were stored in cold chambers at +1 °C for up to 3 weeks and then subjected to a post-harvest maturation in ripening chambers at 20 °C and 60–70% RH up to 7 days. Firmness, soluble solids (SS), titratable acidity (TA), and the levels of the main volatiles were determined. Physicochemical changes included a significant decrease of firmness during both storage and post-harvest maturation whereas the levels of SS and TA were found to be very similar. The results also indicated that, whatever their initial stage of maturity at harvest, the rates of softening of apricots during storage and/or post-harvest maturation were very comparable. During post-harvest maturation, the levels of C₆-compounds decreased drastically whereas, at the same time, those of esters, lactones and terpenic compounds greatly increased. During storage at 1 °C, a decrease of C₆-compounds was also observed. As regards other compounds, there were some statistically different results between samples but the changes observed for lactones, esters and terpenic compounds were relatively small in comparison to those observed during post-harvest maturation at 20 °C. The results also showed that, at the end, qualitative and quantitative differences can be observed in the “ready-to-eat” apricots according to their initial stage of maturity at harvest. On average, apricots harvested at the most advanced stage of maturity have, on average, the highest levels of soluble solids and the highest levels of volatile compounds of interest.     

Variation in contents of phenolic compounds during growth and post-harvest storage of pigeon pea seedlings

The variation in contents of seven phenolic compounds in pigeon pea seedlings during growth and storage was investigated. Maximum contents of vitexin, isovitexin and orientin were found in leaves growing 40 days, which were 0.99 ± 0.06, 6.63 ± 0.35 and 30.89 ± 1.92 mg/g DW. Apigenin and luteolin were extensively distributed in leaves, stems and roots. Pinostrobin and cajaninstilbene acid were mainly accumulated in leaves, the peak values 3.53 ± 0.18 and 2.49 ± 0.13 mg/g DW appeared at the 60th day. Slight and steady increases of seven phenolic compounds were found in room temperature (25 °C) stored pigeon pea leaves up to 120 days. The highest accumulation of seven phenolic compounds at chilling temperature (4 °C) was observed at the 45th day, after which the contents decreased sharply. The stems extracts exhibited more efficient DPPH radical-scavenging ability while the roots extracts demonstrated the strongest lipid peroxidation inhibitory activity.     

Evaluation of spectrophotometric methods for antioxidant compound measurement in relation to total antioxidant capacity in beverages

The validity of different colorimetric methods used to quantify various families of antioxidant compounds was evaluated with standard compounds. The colorimetric tests for global evaluation of flavonoids, anthocyans, and flavanols were found generally unreliable, as reactions could be different for individual compounds within a family (anthocyanins or flavonols or flavan-3-ols) and not specific to one family. In the flavonoid test, for example, flavonols reacted very well, anthocyanins did not react, and flavanons reacted only slightly. The same methods were applied also to beverages known for their antioxidant content (apple, orange, grape, and vegetable juices, ice tea, and red wine) and the data were compared with the results of HPLC analysis of specific compounds. The values obtained in a colorimetric test were generally higher than the sum of the values obtained for the corresponding individual compounds by HPLC analysis, mainly because other compounds can interfere with the colorimetric tests. For example, in wine, anthocyanin concentrations obtained by colorimetric test were 9068 ± 1407 μmol/100 ml (mean ± SEM), higher than the sum of the six main anthocyanidins detected by HPLC, only 41 μmol/100 ml. The relative antioxidant capacity values determined for beverages on the basis of colorimetric tests could exceed by far the values previously measured in radical-scavenging tests (for instance, the antioxidant capacity attributable to anthocyans in wine on the basis of the colorimetric test was 50 times higher than the total antioxidant capacity measured by the ORAC assay). In conclusion, colorimetric tests for flavonoids, anthocyans, and flavanols appeared generally unreliable for estimating their content and thus the antioxidant capacity reliable to these compounds.     

Antioxidant responses in minimally processed celery during refrigerated storage

This work studies the effect of storage temperature (0, 4 and 10 °C) and time on the antioxidant capacity of cut celery packaged in polystyrene trays sealed with PVC film. Samples were taken at 0, 7, 14, 21 and 28 days of storage to determine total phenols, chlorogenic acid and ascorbic acid. The browning potential and antioxidant capacity of the product were also evaluated. The antioxidant power presented similar behaviour for the three temperatures tested, decreasing after the first 7 days and then increasing up to day 14. Such increase coincided with an elevation of the ascorbic acid content, which was stronger for higher temperatures. As a general conclusion, minimally processed celery retained its initial antioxidant capacity for a period of 21 days at 0 °C, showing the lowest levels of browning potential at this temperature.     

Total phenols,ascorbic acid, β-carotene and lycopene in Portuguese wild edible mushrooms and their antioxidant activities

The antioxidant activities of three Portuguese wild edible mushroom species, Leucopaxillus giganteus, Sarcodon imbricatus, andAgaricus arvensis, were evaluated. Methanolic extracts were screened for their reducing power, 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical-scavenging capacity, inhibition of erythrocytes hemolysis and antioxidant activity using the β-carotene linoleate model system. The amounts of ascorbic acid, β-carotene and lycopene found in the mushroom extracts were very low. Otherwise, the high contents of phenolic compounds might account for the good antioxidant properties found in all species. L. giganteus had the highest content of phenols and proved to be the most active, presenting lower EC₅₀ values in all the antioxidant activity assays.     

Changes in physio-biochemical metabolism,phenolics and antioxidant capacity of different Chinese pea varieties during germination

In this study, changes in physiological and biochemical metabolism, phenolics and antioxidant capacity of six different Chinese pea varieties during germination were investigated. Results showed that germination had a positive effect on the physiological indexes and bioactive substances of pea. The bud length, root length, fresh weight and respiration rate of pea sprouts increased with germination time. The content of free and bound phenolics in germinated peas increased significantly. Meanwhile, activated phenylalanine ammonia-lyase (PAL), cinnamate 4-hydroxylase (C4H) and 4-coumaric acid coenzyme A ligase (4CL) led to the accumulation of phenolics. Antioxidant capacity of pea sprouts increased with the extension of germination time. From the perspective of principal component analysis, compared with the other five varieties, Longwan 7 can be distinguished by free phenolic content in the later stage of germination. The result provides a new perspective for further development of pea as a functional food for human consumption.     

Use of kinetic, Weibull and PLSR models to predict the retention of ascorbic acid, total phenols and antioxidant activity during storage of pasteurized pineapple juice

In this study, the usefulness of different mathematical models to predict the retention of ascorbic acid (AA), total phenols (TP) and DPPH radical scavenging activity (SA) of pasteurized pineapple juices during storage has been evaluated. The results indicate that first-order kinetic model provided the best prediction of the degradation of AA (MAE = 0.0059; MRE = 0.0117; MSE = 0.0001; R² = 0.9995) whereas Weibull model provided the less satisfactory prediction (MAE = 0.2387; MRE = 0.2911; MSE = 0.0769; R² = 0.9993). In addition, zero-order (MAE = 0.0016; MRE = 0.0017; MSE = 0.0000; R² = 0.9992) and first-order (MAE = 0.0027; MRE = 0.0029; MSE = 0.0000; R² = 0.9989) kinetic models are adequate models for application in the prediction of TP loss, and first-order kinetic (MAE = 0.0294; MRE = 0.0549; MSE = 0.0015; R² = 0.9845) and Weibull (MAE = 0.0533; MRE = 0.0881; MSE = 0.0044; R² = 0.9823) models are recommended to predict the change of SA. These results show that the behaviors of AA, TP and SA during storage of juices can be accurately described by different prediction models. Therefore, the selection of the most adequate model is of great importance to predict nutritional deterioration in food products during storage.     

Antioxidant capacity,ascorbic acid,total phenols and carotenoids changes during harvest and after storage of Hayward kiwifruit

The influences of harvest time and storage on the quality indices and nutritional content of kiwifruit were evaluated. Antioxidant capacity, ascorbic acid, total phenol content, carotenoids, soluble solids content and flesh firmness were determined in kiwifruit gathered at two different time (T1: 17-11-2005 and T2: 24-11-2005) and stored at 0 °C, for 2 or 6 months (S1 and S2, respectively). At the end of the cool storage, fruits were maintained for a week at 25 °C (S1 + 7d and S2 + 7d).     

Changes in phenolic profile and antioxidant activity during production of diced tomatoes

Tomatoes and tomato-based products are rich in antioxidants such as carotenoids, vitamin C and polyphenols. The industrial processing of diced tomatoes involves heat treatments in which these antioxidant compounds may be potentially affected. In this study, we evaluate the effect of each separate step in the dice-making process. Three technological processes were investigated: Hot, Cold and Cold treated with calcium salt (CaCl₂). Four stages were monitored in each process: (1) fresh tomatoes; (2) peeled tomatoes; (3) diced tomatoes; and (4) final product after sauce addition. The main tool for minimising or counteracting the eventual processing damage was the strategy of ‘reconstitution’, achieved by adding a sauce rich in seeds and peels with high levels of antioxidants and phenolics to the diced tomatoes. Different analyses were carried out in order to evaluate the effect of each processing step. First, total polyphenols (TP) were evaluated using Folin–Ciocalteau (F–C) assay and antioxidant activity using ABTS⁺ and DPPH assays. Flavonols, flavanones, hydroxycinnamic and phenolic acids were then quantified using liquid chromatography/electrospray ionisation tandem mass spectrometry (HPLC–ESI–MS/MS). The combination of principal component analysis (PCA) and analysis of variance (ANOVA) revealed that each processing step induces alterations in the antioxidant and phenolic profile, and in particular sauce addition and calcium treatment significantly affected the levels of antioxidants and phenolics during the dice-making process.     

Changes occurring in compositional components of black soybeans maintained at room temperature for different storage periods

Changes in compositional components of black soybeans, including isoflavone, anthocyanin, protein, oil, and fatty acid, were investigated for the first time in soybeans maintained at room temperature for different storage periods. Isoflavone and anthocyanin profiles in hydrolysed extracts were characterised by column chromatography and HPLC-DAD-ESI/MS spectrometry analysis. These components decreased markedly during storage, whereas protein, oil, and fatty acid showed a slight decrease. The individual isoflavones and anthocyanins observed in black soybeans were as follows, in order of abundance: genistein > daidzein > glycitein; cyanidin-3-O-glucoside > dephinidin-3-O-glucoside > petunidin-3-O-glucoside. In particular, genistein (518.4 → 415.7 → 274.8 μg/g) and cyanidin-3-O-glucoside (6.53 → 2.92 → 1.49 mg/g) showed the greatest decrease for a storage time of two years. The scavenging activities of DPPH and ABTS radicals during storage also decreased in comparison with those of observed before storage. Our results can be used to improve our understanding of the relationship between storage times and the components from black soybeans.