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8 pages, 4 figures, 1 table., The use of regulated deficit irrigation (RDI) strategies is becoming a common practice in areas with low water availability. Little information is available about the effects of RDI on the antioxidant content of fruits. In this study, the influence of RDI on the content of vitamin C, phenolic compounds and carotenoids was investigated. Two irrigation strategies, fully irrigated (FI) and RDI, were compared at two levels of thinning, commercial and half of the commercial crop load. RDI strategies affected the content of vitamin C, phenolics and carotenoids of Flordastar peaches. RDI caused fruit peel stress lowering the content of vitamin C and carotenoids, while increasing the phenolic content, mainly anthocyanins and procyanidins. Fruit weight was the only quality index influenced by the crop load as it increased in FI fruits at low crop load. In general, fruits from commercial crop load had slightly higher content of antioxidants to fruits from low crop load, although these influences were only observed in the peel. Additionally, the influence of irrigation controlled by two sensors related to plant water level, maximum daily trunk shrinkage (MDS) and sap flow (SF) on the antioxidant constituents of peaches was evaluated. The response of the fruits to SF sensor was similar to that observed for RDI strategy. According to the tested water sensors, SF did not act as a good plant-based water indicator for use in irrigation scheduling, as it caused an increase in the content of phenolics, similar to that observed for fruits subjected to RDI. Therefore, selection of RDI strategies and plant water indicators should be taken into account as they affect the content of antioxidants of peaches., We are grateful to the IRRIQUAL project (FP6-FOOD-CT-2006-023120) and CSD-67 Grant (Consolider-Ingenio 2010 Programme) for financial support.

7 pages, 5 figures, 1 table., This study investigated the efficacy of ultraviolet-C (254 nm) and induced stilbenes to inhibit Aspergillus carbonarius and Aspergillus tubingensis and control ochratoxin A production in grapes. In addition, the stilbene synthesis as a response to UV-C treatment and to infection of ochratoxigenic Aspergillus was compared. The initial microbial inactivation by a previously optimized UV-C illumination protocol for increasing trans-resveratrol content in grapes (50 W/m2, 40 cm, 60 s) was similar on undamaged and damaged grapes, achieving 1.2 and 1.3 log conidia/100 g reductions, respectively. After 5 days of storage at 22 °C, UV-C treatment and the stilbenes induced by UV-C inhibited ochratoxigenic Aspergillus growth in undamaged grapes. UV-C elicited the biosynthesis of trans-resveratrol, while microbial infection and tissue damage triggered the biosynthesis of trans-piceid. trans-Resveratrol was not synthesized as a consequence of ochratoxigenic Aspergillus contamination. However, when trans-resveratrol was synthesized by UV-C, it contributed to inhibiting the development of ochratoxin A producing aspergilli. Furthermore, UV-C treatment also contributed to decrease ochratoxin A production by ochratoxigenic aspergilli. Therefore, UV-C is a promising emerging technology either for reducing the potential ochratoxigenic risk in grapes, which is of particular interest to the wine industry, and also for increasing trans-resveratrol content of grapes, which would provide an added value to the wine., We are grateful to Spanish CICYT (Comisin Interministerial de Ciencia y Tecnologa) project AGL2007-65056 for financial support and M.V.S. to the CSIC (Spanish National Research Council) for the I3P contract (I3PDR-7-01).

8 pages, 4 figures, 3 tables., Integrated, organic, and soil-less production systems are the principal production practices that have emerged to encourage more sustainable agricultural practices and safer edible plants, reducing inputs of plaguicides, pesticides, and fertilizers. Sweet peppers grown commercially under integrated, organic, and soil-less production systems were compared to study the influence of these sustainable production systems on the microbial quality and bioactive constituents (vitamin C, individual and total carotenoids, hydroxycinnamic acids, and flavonoids). The antioxidant composition of peppers was analyzed at green and red maturity stages and at three harvest times (initial, middle, and late season). Irrigation water, manure, and soil were shown to be potential transmission sources of pathogens to the produce. Coliform counts of soil-less peppers were up to 2.9 log units lower than those of organic and integrated peppers. Soil-less green and red peppers showed maximum vitamin C contents of 52 and 80 mg 100 g-1 fresh weight (fw), respectively, similar to those grown in the organic production system. Moreover, the highest content of total carotenoids was found in the soil-less red peppers, which reached a maximum of 148 mg 100 g-1 fw, while slightly lower contents were found in integrated and organic red peppers. Hydroxycinnamic acids and flavonoids represented 15 and 85% of the total phenolic content, respectively. Total phenolic content, which ranged from 1.2 to 4.1 mg 100 g-1 fw, was significantly affected by the harvest time but not by the production system assayed. Soil-less peppers showed similar or even higher concentrations of bioactive compounds (vitamin C, provitamin A, total carotenoid, hydroxycinnamic acids, and flavonoids) than peppers grown under organic and integrated practices. Therefore, in the commercial conditions studied, soil-less culture was a more suitable alternative than organic or integrated practices, because it improved the microbial safety of sweet peppers without detrimental effects on the bioactive compound content.

11 pages, 6 tables, 3 figures., A comparative study of antioxidant compounds, flavonoids and vitamin C, and also antioxidant activity was carried out in four species of Brassicaceae vegetables used for salads: watercress (Nasturtium officinale R. Br.), mizuna [Brassica rapa L. subsp. nipposinica (L.H. Bailey) Haneltand], wild rocket [Diplotaxis tenuifolia (L.) DC.], and salad rocket [Eruca vesicaria (L.) Cav.]. The characterization of individual phenolic compounds by HPLC-DAD-MS/MS-ESI in watercress and mizuna completes the polyphenol study previously reported for wild rocket and salad rocket. The qualitative study of flavonoids in watercress leaves showed a characteristic glycosylation pattern with rhamnose at the 7 position. Isorhamnetin 3,7-di-O-glucoside was identified in mizuna leaves and may be considered a chemotaxonomical marker in some B. rapa subspecies. Brassicaceae species showed differences in the quantitative study of flavonoids, and the highest content was detected in watercress leaves. Watercress and wild rocket leaves had the highest content of vitamin C. The antioxidant activity evaluated by different methods (ABTS, DPPH, and FRAP assays) showed a high correlation level with the content of polyphenols and vitamin C. In conclusion, the Brassicaceae leaves studied, watercress, mizuna, wild rocket, and salad rocket, presented a large variability in the composition and content of antioxidant compounds. These baby leaf species are good dietary sources of antioxidants with an important variability of bioactive compounds., The authors are grateful to the Spanish CICYT (AGL2007-65056/ALI) for financial support and to AMS for a FPU grant from MEC (AP2003-3990). This research group belongs to the Spanish Consolider-Ingenio 2010 program CSD2007-00063 FUN-C-FOOD.

7 pages, 3 figures, 6 tables., Thirty-seven apricot varieties, including four new releases (Rojo Pasión, Murciana, Selene, and Dorada) obtained from different crosses between apricot varieties and three traditional Spanish cultivars (Currot, Mauricio, and Búlida), were separated according to flesh color into four groups. The L*, a*, b*, hue angle, and chroma color measurements on the skin and flesh as well as other quality indices including flesh firmness, soluble solids, titratable acidity, and pH were plotted against the total carotenoid content measured by HPLC. Among the 37 apricot varieties, the total carotenoid content ranged from 1512 to 16500 μg 100 g-1 of edible portion, with β-carotene as the main pigment followed by β-cryptoxanthin and γ-carotene. The wide range of variability in the provitamin A content in the apricot varieties encouraged these studies in order to select the breeding types with enhanced carotenoid levels as the varieties with a higher potential health benefit. The carotenoid content was correlated with the color measurements, and the hue angle in both flesh and peel was the parameter with the best correlation (R = 0.92 and 0.84, respectively). An estimation of the carotenoid content in apricots could be achieved by using a portable colorimeter, as a simple and easy method for field usage applications., We are grateful to Spanish CICYT (Comisión Interministerial de Ciencia y Tecnología) Project AGL2001-1122-CO2-01 for financial support. D.R. is holder of a grant from Consejo Superior de Investigaciones Científicas (reference I3PBPD 2001-1).

9 pages, 5 tables, 3 figures., Sweet peppers (Capsicum annuum L.) cv. Vergasa have been studied at four maturity stages (immature green, green, immature red, and red). The individual phenolics (hydroxycinnamic acids and flavonoids), vitamin C (ascorbic acid and dehydroascorbic acid), and individual carotenoids were characterized and quantified. Five hydroxycinnamic derivatives and 23 flavonoids were characterized and quantified from the pericarp of sweet pepper by high-performance liquid chromatography−diode array detection−electrospray ionization−mass spectrometry. Identification was carried out by their UV spectra, chromatographic comparisons with authentic markers, identification of hydrolysis products, and tandem mass spectrometry analysis. Hydroxycinnamic derivatives, O-glycosides of quercetin, luteolin, and chrysoeriol, and a large number of C-glycosyl flavones have been characterized. Some of these compounds were found for the first time in nature. Clear differences in the individual and total phenolic content were detected between the different maturity stages. Immature green pepper had a very high phenolic content while green, immature red, and red ripe peppers showed a 4−5-fold reduction. Ascorbic acid was the main form of vitamin C, and its content increased as the pepper reached maturity. The red ripe stage had a relevant impact on the carotenoids content. Thus, immature green peppers showed the highest content of polyphenols, while red ripe fruits had the highest content of vitamin C and provitamin A., We are grateful to Spanish CICYT (Comisión Interministerial de Ciencia y Tecnología) Projects AGL2000-0452-P4-03 and AGL2001-1269 for financial support.

7 pages, 1 figure, 13 tables., Genotypic variation in composition and antioxidant activity was evaluated using 25 cultivars, 5 each of white-flesh nectarines, yellow-flesh nectarines, white-flesh peaches, yellow-flesh peaches, and plums, at the ripe (ready-to-eat) stage. The ranges of total ascorbic acid (vitamin C) (in mg/100 g of fresh weight) were 5−14 (white-flesh nectarines), 6−8 (yellow-flesh nectarines), 6−9 (white-flesh peaches), 4−13 (yellow-flesh peaches), and 3−10 (plums). Total carotenoids concentrations (in μg/100 g of fresh weight) were 7−14 (white-flesh nectarines), 80−186 (yellow-flesh nectarines), 7−20 (white-flesh peaches), 71−210 (yellow-flesh peaches), and 70−260 (plums). Total phenolics (in mg/100 g of fresh weight) were 14−102 (white-flesh nectarines), 18−54 (yellow-flesh nectarines), 28−111 (white-flesh peaches), 21−61 (yellow-flesh peaches), and 42−109 (plums). The contributions of phenolic compounds to antioxidant activity were much greater than those of vitamin C and carotenoids. There was a strong correlation (0.93−0.96) between total phenolics and antioxidant activity of nectarines, peaches, and plums.

6 pages, 1 figure, 3 tables., Total phenolic content and antioxidant capacity of 11 commercial cultivars and 15 advanced breeding lines of spinach were determined over two growing seasons known to vary in biotic and abiotic stresses. Flavonoid composition and content of fall-grown commercial cultivars and advanced breeding lines were also determined. Over-winter spinach, which was planted in late fall and harvested in the spring, had much higher levels of total phenolics and antioxidant capacity than spinach planted in early fall and harvested in late fall, indicating that growing conditions, as well as biotic and abiotic stresses, influenced phenolic metabolism. Genotype also appeared to play an important role in affecting phenolic metabolism and antioxidant capacity in spinach. Advanced breeding lines of spinach, which show increased disease resistance, had higher levels of total phenolics, individual and total flavonoids, and antioxidant capacity than commercial cultivars. Our results indicate that plant breeders can select for increased phenolic content to increase antioxidant capacity in spinach cultivars, or the crops can be grown in different seasons or under certain stress conditions to elevate levels of antioxidants.

13 pages, 3 figures, 14 tables., The phenolic compounds of 25 peach, nectarine, and plum cultivars were studied and quantified by HPLC−DAD−ESIMS. Hydroxycinnamates, procyanidins, flavonols, and anthocyanins were detected and quantified. White and yellow flesh nectarines and peaches, and yellow and red plums, were analyzed at two different maturity stages with consideration of both peel and flesh tissues. HPLC−MS analyses allowed the identification of procyanidin dimers of the B- and A-types, as well as the presence of procyanidin trimers in plums. As a general rule, the peel tissues contained higher amounts of phenolics, and anthocyanins and flavonols were almost exclusively located in this tissue. No clear differences in the phenolic content of nectarines and peaches were detected or between white flesh and yellow flesh cultivars. There was no clear trend in phenolic content with ripening of the different cultivars. Some cultivars, however, had a very high phenolic content. For example, the white flesh nectarine cultivar Brite Pearl (350−460 mg/kg hydroxycinnamates and 430−550 mg/kg procyanidins in flesh) and the yellow flesh cv. Red Jim (180−190 mg/kg hydroxycinnamates and 210−330 mg/kg procyanidins in flesh), contained 10 times more phenolics than cultivars such as Fire Pearl (38−50 mg/kg hydroxycinnamates and 23−30 mg/kg procyanidins in flesh). Among white flesh peaches, cultivars Snow King (300−320 mg/kg hydroxycinnamates and 660−695 mg/kg procyanidins in flesh) and Snow Giant (125−130 mg/kg hydroxycinnamates and 520−540 mg/kg procyanidins in flesh) showed the highest content. The plum cultivars Black Beaut and Angeleno were especially rich in phenolics.

7 pages, 1 figure, 5 tables., Hand-squeezed navel orange juice contains 839 mg/L phenolics, including flavanones, flavones, and hydroxycinnamic acid derivatives. The flavanones are the main phenolics in the soluble fraction (648.6 mg/L) and are also present in the cloud fraction (104.8 mg/L). During refrigerated storage of fresh juice (4 °C), 50% of the soluble flavanones precipitate and integrate into the cloud fraction. Commercial orange juices contain only 81−200 mg/L soluble flavanones (15−33%) and the content in the cloud is higher (206−644 mg/L) (62−85%), showing that during industrial processing and storage the soluble flavanones precipitate and are included in the cloud. An in vitro simulation of orange juice digestion shows that a serving of fresh orange juice (240 mL) provides 9.7 mg of soluble hesperidin (4‘-methoxy-3‘,5,7-trihydroxyflavanone-7-rutinoside) and 4.7 mg of the C-glycosylflavone vicenin 2 (apigenin, 6,8-di-C-glucoside) for freshly squeezed orange juice, whereas pasteurized commercial juices provide 3.7 mg of soluble hesperidin and a higher amount of vicenin 2 (6.3 mg). This means that although orange juice is a very rich source of flavanones, only a limited quantity is soluble, and this might affect availability for absorption (11−36% of the soluble flavanones, depending on the juice). The flavanones precipitated in the cloud are not available for absorption and are partly transformed to the corresponding chalcones during the pancreatin−bile digestion., This work has been financially supported by the Spanish CICYT (Grant ALI98-0843). A.G.-I. is grateful to the Spanish MEC for a predoctoral fellowship.

9 pages, 4 figures, 6 tables., The antioxidant activity of pomegranate juices was evaluated by four different methods (ABTS, DPPH, DMPD, and FRAP) and compared to those of red wine and a green tea infusion. Commercial pomegranate juices showed an antioxidant activity (18−20 TEAC) three times higher than those of red wine and green tea (6−8 TEAC). The activity was higher in commercial juices extracted from whole pomegranates than in experimental juices obtained from the arils only (12−14 TEAC). HPLC-DAD and HPLC-MS analyses of the juices revealed that commercial juices contained the pomegranate tannin punicalagin (1500−1900 mg/L) while only traces of this compound were detected in the experimental juice obtained from arils in the laboratory. This shows that pomegranate industrial processing extracts some of the hydrolyzable tannins present in the fruit rind. This could account for the higher antioxidant activity of commercial juices compared to the experimental ones. In addition, anthocyanins, ellagic acid derivatives, and hydrolyzable tannins were detected and quantified in the pomegranate juices., This research project was supported, in part, by a grant from Paramount Farming Co., Bakersfield, CA.