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The metabolism of phenolic compounds is a key factor in the development of wound-induced enzymatic browning of fresh-cut lettuce. In the present study, the lettuce midribs discriminant metabolites, selected in a previous untargeted metabolomics study, were thoroughly identified. Our results showed that their basal contents correlated with browning developed after 5 days of storage. 5- trans-Chlorogenic acid and 5- cis-chlorogenic acid were positively correlated with browning, while sinapaldehyde and its 4-β-d-glucoside and 4-(6'-malonyl)-β-d-glucoside conjugates were negatively correlated. Using targeted metabolomics, the metabolites were analyzed in lettuce heads with different degrees of development and different browning susceptibility and these biomarkers were confirmed. Despite the large variability in the browning process of lettuce, the chlorogenic acids/sinapaldehyde derivatives ratio showed a linear correlation ( r2 = 0.79) with the fresh-cut lettuce browning developed in 24 Romaine lettuce cultivars, validating the relevance of these biomarkers. These results show that the analysis of the basal content of these metabolites could be used in lettuce breeding programs to select cultivars that are more appropriate for the fresh-cut industry.

Enzymatic browning is one of the main causes of quality loss in lettuce as a prepared and ready-to-eat cut salad. An untargeted metabolomics approach using UPLC-ESI-QTOF-MS was performed to explain the wound response of lettuce after cutting and to identify the metabolites responsible of browning. Two cultivars of Romaine lettuce with different browning susceptibilities were studied at short time intervals after cutting. From the total 5975 entities obtained from the raw data after alignment, filtration reduced the number of features to 2959, and the statistical analysis found that only 1132 entities were significantly different. Principal component analysis (PCA) clearly showed that these samples grouped according to cultivar and time after cutting. From those, only 15 metabolites belonging to lysophospholipids, oxylipin/jasmonate metabolites, and phenolic compounds were able to explain the browning process. These selected metabolites showed different trends after cutting; some decreased rapidly, others increased but decreased thereafter, whereas others increased during the whole period of storage. In general, the fast-browning cultivar showed a faster wound response and a higher raw intensity of some key metabolites than the slow-browning one. Just after cutting, the fast-browning cultivar contained 11 of the 15 browning-associated metabolites, whereas the slow-browning cultivar only had 5 of them. These metabolites could be used as biomarkers in breeding programs for the selection of lettuce cultivars with lower browning potential for fresh-cut applications.

7 páginas, 6 figuras, 4 tablas., The effect of soil amendments prepared from organic wastes (sewage sludge and urban solid waste) at two concentrations (45 t ha−1 as D1 and 135 t ha−1 as D2) was evaluated on phytochemicals and microbial quality of rocket, a highly valuable vegetable. The addition of sewage sludge to the soil increased rocket yield 5.5 times compared to control and urban solid waste. Organic amendments increased the water content and the maturity stage of the leaves, which contributed to a reduction in the content of total and individual glucosinolates as well as flavonols and anthocyanins. However, higher content of vitamin C was observed after cultivation with sewage sludge at D2 compared to control leaves (204.6 and 177.4 mg 100 g−1 of fw, respectively). This study shows that sewage sludge at optimum doses can be considered a suitable amendment because of increased crop yield without detrimental effects on phytochemicals, including vitamin C content, when the leaves reached the commercial maturity stage., The research leading to these results has received funding from CICYT (Project AGL2007-65056) and the European Community’s Seventh Framework Programme (FP7) under grant agreement no 244994 (project VEG-i-TRADE). M.V.S. is holder of a “Ramón y Cajal” contract from the MCINN and A.M.S of a Postdoctoral grant from MCINN.

This study describes the effect of water stress and storage time on the content of anthocyanins and other phenolics in different genotypes of fresh sweet basil (Ocimum basilicum L.). Purple and green Iranian cultivars and a Genovese variety were exposed to a control (100% of the field capacity, FC) and to water stress of mild and severe deficit irrigation treatments (25 and 50 DI corresponding to 75 and 50% FC, respectively). The individual characterization by HPLC-DAD-ESI/MS(n) and the MS fragmentation pathway of anthocyanins are described. A 50% increase in the anthocyanin content was observed in 50 DI after storage. Water stress markedly enhanced the content of phenolic acids after storage in the three genotypes. Water stress can be an efficient way to help the sustainability of water resources, enriching the content of phenolic compounds that may be beneficial to human health.

The lack of consistency in homogeneous color throughout the season of pigmented baby leaf lettuce is a problem for growers because of the rejection of the product and consequently the economic loss. Changes in color as well as individual and total phenolic composition and content as a response to the climatic variables were studied following the analysis of three pigmented baby leaf lettuces over 16 consecutive weeks from February to May, which corresponded to the most important production season in winter in Europe. Color and phenolic content were significantly (P ≤ 0.001) affected by cultivar, harvest week, and climatic variables that occurred in the last week before harvest. Radiation and temperature showed positive correlations with the content of phenolic acids and flavonoids that increased in all three cultivars as the season progressed. Cyanidin-3-O-(6''-O-malonyl)-glucoside content showed positive correlations with temperature and radiation but only in Batavia cultivars whereas in red oak leaf the correlation was with cold temperatures. Regarding hue angle, a positive correlation was shown with the number of hours at temperatures lower than 7 °C. A relationship between hue angle and the content of anthocyanins was not possible to establish. These results suggest that the colorimetric measurement of color cannot be used as a good indicator of anthocyanin accumulation because other pigments such as chlorophylls and carotenoids may contribute as well to the leaf color of pigmented lettuce. This study provides information about the impact of genotype and environment interactions on the biosynthesis of phenolic compounds to explain the variability in the leaf color and product appearance.

7 pages, 12 figures., Postharvest treatment of seedless white table grapes (var. ‘Superior') with different gas ozone concentrations (3.88 and 1.67 g/h) for 1, 3, and 5 h induced an increase in stilbenoid biosynthesis [trans-resveratrol, piceatannol, and viniferinas (resveratrol dehydrodimers and dehydrotrimers)] during storage at 22 °C and 95% relative humidity. The maximal resveratrol concentration was reached after 2 days of storage, and this amount was similar to that induced by optimized UV-C treatments (1 min, 510 W, 40 cm). Although similar resveratrol concentrations accumulated in grapes after both UV-C and O3 treatments (maximum ozone production and time), the ozone treatment was more efficient in inducing viniferins accumulation in grape berries. A sequence in the biosynthesis of stilbenoids was observed, starting with the resveratrol monomer, continuing with the resveratrol dehydrodimers ε-viniferin and δ-viniferin, and ending with four different resveratrol dehydrotrimers. These trimers were different from α-viniferin, a trimer previously reported to be induced in grapes after biotic and abiotic stresses. Two α-viniferin isomers were also detected in the ozone-treated grapes, although at very low concentrations that prevented their quantification., This work has been financially supported by the Spanish CICYT Projects AGL-2001-1269 and PTR-95-0808-OP and by the Commission of The European Communities, specific RTD Program ‘Quality of Life and Management of Living Resources’, Project QLK1-CT-2002-02364 (‘Novel enzyme-aided extraction technologies for maximized yield and functionality of bioactive components in consumer products and ingredients from byproducts’, acronym ‘MAXFUN’). R.GB.. is a holder of a contract from the MAXFUN project. E.C. is holder of a postdoctoral contract from AINIA (Spain). D.B. is holder of a fellowship from the Ministerio de Educación y Ciencia (Spain).

6 pages, 4 tables, 5 figures., Spinach leaves harvested at three maturity stages from eight commercial cultivars (CC) and eight advanced breeding lines (ABL) were evaluated for oxygen radical absorbing capacity (ORAC), total phenolics, and flavonoid composition and content. ABL had higher levels of total phenolics, total flavonoids, and ORAC than CC. Midmaturity spinach leaves had higher levels of total phenolics, total flavonoids, and antioxidant capacity than immature and mature leaves. The contents of individual flavonoids varied in response to maturation, with the predominant glucuronated flavones decreasing and patuletin and spinacetin derivatives increasing. Both total phenolics and total flavonoids correlated well with ORAC (rxy = 0.78 and 0.81, respectively) demonstrating that flavonoids were major contributors to antioxidant capacity. Our results indicate that spinach genotypes should be harvested at the midmaturity stage for consumers to benefit from elevated levels of health promoting flavonoids present in the leaves. Additionally, plant breeders can select for increased phenolic content to increase antioxidant capacity of spinach genotypes., This work was funded by an Initiative for Future Agricultural and Food Systems/Cooperative State Research, Education, and Extension Service grant.

7 pages, 6 figures, 2 tables., The effect of fresh-cutting and subsequent cold storage on phenolic compounds from five long-term-stored potato cultivars (Agria, Cara, Liseta, Monalisa, and Spunta) was studied. Fresh-cutting induced the biosynthesis of three flavonols, which were identified by HPLC-DAD-ESIMS as quercetin 3-rutinoside, quercetin 3-diglucoside, and quercetin 3-glucosylrutinoside. The flavonols were detected after a lag period of 3 days of cold storage. The content ranged from 6 to 14 mg/100 g of fresh weight depending on the cultivar after 6 days of storage. Chlorogenic acid as the main caffeic acid derivative and the amino acids tyrosine and tryptophan were also quantified. The effect of cold storage under light or in dark was studied with new-season-harvested Monalisa potatoes. The flavonol induction was higher in fresh-cut potatoes stored under light than in the dark. However, caffeic acid derivatives were not affected. Domestic cooking such as boiling, microwaving, and frying provoked a partial loss of the flavonols, which were retained in the range of 4−16 mg per serving (213 g). Steam-cooking resulted in the highest retention of caffeic acid derivatives and aromatic amino acids compared with the other cooking methods studied. This means that due to the large amount of potatoes consumed in the Western diet, fresh-cut potatoes can be a significant source of health-promoting phenolics., We are grateful to FEDER- Ministerio de Ciencia y Tecnología for financial support (Grants AGL2000-0452-P4-03, AGL2001-1125, and AGL2001-1269). J.A.T. has a fellowship from the Ministerio de Educación, Cultura y Deporte (FPU), and E.C. is holder of a grant from the Ministerio de Ciencia y Tecnología (MIT-F2).

8 pages, 4 figures, 2 tables., Phenolic compounds, vitamin C (l-ascorbic acid and l-dehydroascorbic acid), and antioxidant capacity were evaluated in orange juices manufactured by different techniques. Five processes at industrial scale (squeezing, mild pasteurization, standard pasteurization, concentration, and freezing) used in commercial orange juice manufacturing were studied. In addition, domestic squeezing (a hand processing technique) was compared with commercial squeezing (an industrial FMC single-strength extraction) to evaluate their influences on health components of orange juice. Whole orange juice was divided into soluble and cloud fractions after centrifugation. Total and individual phenolics were analyzed in both fractions by HPLC. Commercial squeezing extracted 22% more phenolics than hand squeezing. The freezing process caused a dramatic decrease in phenolics, whereas the concentration process caused a mild precipitation of these compounds to the juice cloud. In pulp, pasteurization led to degradation of several phenolic compounds, that is, caffeic acid derivatives, vicenin 2 (apigenin 6,8-di-C-glucoside), and narirutin (5,7,4‘-trihydroxyflavanone-7-rutinoside) with losses of 34.5, 30.7, and 28%, respectively. Regarding vitamin C, orange juice produced by commercial squeezing contained 25% more of this compound than domestic squeezing. Mild and standard pasteurization slightly increased the total vitamin C content as the contribution from the orange solids parts, whereas concentration and freezing did not show significant changes. The content of l-ascorbic acid provided 77−96% of the total antioxidant capacity of orange juice. Mild pasteurization, standard pasteurization, concentration, and freezing did not affect the total antioxidant capacity of juice, but they did, however, in pulp, where it was reduced by 47%., This work has been funded by a Spanish CICYT (Comisión Interministerial de Ciencia y Tecnología) grant, Projects ALI98-0843 and AGL2001-1125. A.G.I. is holder of a predoctoral grant from the Spanish Ministry of Education and Culture.

The effect of modified atmosphere packaging (MAP) and cooking on the flavonoids and vitamin C content (ascorbic + dehydroascorbic acid; AA + DHAA) of fresh-cut spinach was evaluated. The total flavonoid content (approximately 1000 mg kg(-)(1) f.w.) remained quite constant during storage in both air and MAP atmospheres, while vitamin C (750 mg kg(-)(1)f.w.) was better preserved in MAP-stored spinach. AA was transformed to DHAA during storage, and its concentration was higher in MAP-stored tissues. The free-radical scavenging activity of the isolated flavonoids was tested, and only those flavonoids with either a dihydroxyl grouping or acylated with ferulic acid showed significant activity. A decrease in the total antioxidant activity was observed during storage, particularly important in MAP-stored spinach. The higher content of DHAA and lower content of both AA and antioxidant flavonoids in the MAP-stored samples could explain this antioxidant activity decrease. Boiling extracted 50% of total flavonoids and 60% vitamin C in the cooking water. However, flavonoid glucuronides were extracted more in the cooking water than the other glycosides. The vitamin C content of the cooked tissue was higher in those samples stored in MAP.

Five flavonoids from Swiss chard leaves (Beta vulgaris subsp. cycla) cultivar “green” were isolated and identified as vitexin 2‘‘-xyloside and its 6‘‘-malonated derivative, kaempferol 3-gentiobioside, isorhamnetin 3-gentiobioside, and isorhamnetin 3-vicianoside. 6‘‘-Malonyl-2‘‘-xylosyl vitexin is a new naturally occurring flavonoid. In fact, this is the first time that a flavonoid C-glycoside acylated with a dicarboxylic acid is reported in nature. The flavonoid content of fresh leaves (green cultivar) was in the range 2.4−3.0 mg/g fresh weight (f.w.). Cultivar “yellow” contained only flavone C-glycosides (2.1−2.3 mg/g f.w.), while the flavonols were not detected. Their vitamin C content was between 0.4 and 0.5 mg/g f.w., and after domestic processing an 80% loss was observed. Modified atmosphere packaging (MAP) (7% O2 and 10% CO2) had no effect on total flavonoid content after 8 days of storage, although it increased flavonoid extraction during cooking in boiling water. In contrast, vitamin C content dec...

Carbon dioxide-enriched atmospheres are used to reduce the incidence and severity of decay and to extend the postharvest life of strawberries. The influence of CO2 on the postharvest quality parameters of strawberries, particularly the stability of anthocyanins and other phenolic compounds, was investigated. Freshly harvested strawberries were placed in jars ventilated continuously with air or air enriched with 10%, 20%, or 40% CO2 at 5 °C for 10 days. Samples were taken initially, and after 5 and 10 days of storage, and color (L* a* b* color space), pH, TA, TSS, and firmness were measured. Anthocyanins and other phenolics were analyzed by HPLC. Elevated CO2 degraded internal color while air-treated fruit remained red. Internal and external tissues differed in composition and concentration of phenolic compounds. CO2had a minimal effect on the anthocyanin content of external tissues but induced a remarkable decrease in anthocyanin content of internal tissues. Factors, such as pH and copigmentation, that could explain this degradation are discussed.

Wound-induced changes in phenolic metabolism causes stem browning (butt discoloration) in harvested lettuce. Stem tissue near the harvesting cut exhibited increased phenylalanine ammonialyase (PAL) activity and accumulation of caffeic acid derivatives. These o-diphenols can be oxidized by the enzyme polyphenol oxidase (PPO) to produce brown pigments. This browning reaction can readily be followed by measuring a* values. Browning was reduced by washing stem disks with solutions of 0.3 M calcium chloride, 1.0 mM 2,4-dichlorophenoxyacetic acid (2,4-D), or 0.5 M acetic acid. These browning inhibitors appear to act in different ways. Calcium chloride decreased PAL activity to 60% of the control, but did not substantially affect the accumulation of phenolic compounds. The mechanism of calcium action could be to decrease PPO activity or to preserve membrane structure. PAL activity was inhibited 60% by 2,4-D, and the biosynthesis of phenolic compounds was strongly inhibited but not suppressed. Acetic acid completely inhibited PAL activity and the production of wound-induced phenolics. PAL was irreversibly inhibited by acetic acid, and this may explain its role as a browning inhibitor.

Phenolic metabolites present in rosemary honey and floral nectar were studied to find biochemical markers for honey floral origin. Rosemary nectar, from bee honey stomach, contained kaempferol 3-sophoroside (93%) and quercetin 3-sophoroside (7%) as the only significant constituents. All samples had a common flavonoid profile comprised of 15 flavonoids. Nectar glycosides were not detected in honey suggesting that they are hydrolyzed by the bee enzymes to render the corresponding aglycons. Honey flavonoid profiles were similar to those found for propolis, a plant resin collected by bees, and confirmed that the majority of the flavonoids present in honey originate from this source. The amount of kaempferol in the honey samples ranged between 0.4 and 1.2 μg/g. The coefficient of variation of kaempferol in the honey samples was much smaller than those observed for the rest of flavonoids, supporting its floral origin, and the propolis origin for the rest of flavonoids. The presence of kaempferol in rosemary honey cannot be considered as proof of its floral origin because this flavonol can originate from different flower nectars. However, its absence or presence in small levels (

The influence of deficit irrigation (Deficit) and reflective mulch (Reflective) of Caldesi 2000 nectarines on the content of individual phenolic compounds was studied at harvest and during storage for 2, 4, and 6 weeks at 2 °C during two consecutive years (2007 and 2008). Individual phenolic groups in the edible fruit part consisted mainly of proanthocyanidins (200 mg/100 g fw), lower content of phenolic acids (17 mg/100 g fw), and minor content of flavonols (5 mg/100 g fw) and anthocyanins (1.2 mg/100 g fw). Deficit irrigation increased the content of total phenolics, including proanthocyanidins and phenolic acids, reaching similar amounts in both years. Sun-exposed fruit (upper part of canopy) showed higher content than shaded fruit (lower part of canopy). However, Reflective significantly increased the content of total phenolics, particularly phenolic acids and proanthocyanidins, of fruit located in the lower part of the canopy. During storage, Deficit and Reflective did not affect the content of phenolic acids, flavonols, and proanthocyanidins when compared to the content at harvest. Optimizing cultural practices can be a way to increase the phenolic content of nectarines.

The phenolic compounds of 15 strawberry cultivars grown in Spain were analyzed and quantified: anthocyanins (20.2-47.4 mg/100 g of fw) (cyanidin 3-glucoside and pelargonidin 3-glucoside, 3-rutinoside, and 3-malonyl glucoside), flavonols (1.5-3.4 mg/100 g of fw) (quercetin 3-glucuronide and kaempferol 3-glucoside and 3-p-coumaroyl-glucoside), proanthocyanidins (53.9-163.2 mg/100 g), p-coumaroyl-glucose (0.84-6.70 mg/100 g), ellagitannins (9.67-22.86 mg/100 g) (sanguiin H-6, lambertianin C, and galloyl bis-HHDP-glucose), and ellagic acid glycosides (0.88-2.06 mg/100 g of fw) (two ellagic acid deoxyhexosides). Proanthocyanidins, the main phenolic compounds, were characterized by phloroglucinol degradation. Their mean degree of polymerization ranged from 3.4 for cv. Chiflon to 5.8 for cv. Ventana, the average value being 4.3. The terminal unit of proanthocyanidin oligomers was always (epi)catechin (17.36-29.93%) and (epi)catechin (61.66-75.39%) or (epi)afzelechin (4.50-10.54%) as extension units. Different combinations of (epi)catechin and (epi)afzelechin were detected, and their sequence of linkage was characterized by HPLC-MS-MS. Relative percentages of dimers, trimers, tetramers, and pentamers were evaluated by the extracted ion chromatogram (EIC) analysis.

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.

8 pages, 4 figures, 1 table., “Rocket” is a collective name used to term some species within the Eruca and Diplotaxis genera, whose leaves are characterized by a more or less pungent taste. Different approaches have been carried out to differentiate both genera that have similar leaf morphologies. Following our research in flavonoid profiling of the Brassicaceae family using high-performance liquid chromatography/ultraviolet−diode array detection/electrospray ionization mass spectroemtry, we have investigated Eruca vesicaria and Diplotaxis tenuifolia leaf samples as new ingredients of fresh salads. The MS/MS study allowed the identification of new naturally occurring quercetin mono- and diacyl-tri-O-glucosides and the elucidation of the flavonoid glycosylation and acylation patterns. Important differences between flavonoid profiles of E. vesicaria and D. tenuifolia were observed. E. vesicaria contained kaempferol derivatives as principal compounds whereas D. tenuifolia instead accumulated quercetin derivatives. The exhaustive study of the profiling of these species could help further studies concerning the bioavailability of these flavonoids for epidemiological or clinical intervention studies because these species have considerable potential as healthy leafy salads because of the bioactive phytochemicals., We are grateful to Spanish CICYT (Comisio´n Interministerial de Ciencia y Tecnología) project AGL2004-03060 for financial support. A.M.S. is the holder of a grant FPU from Ministerio de Educación y Ciencia (Spain) reference AP2003-3990.

9 pages, 8 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: white, yellow, light orange, and orange (mean hue angles in flesh were 88.1, 85.0, 77.6, and 72.4, respectively). Four phenolic compound groups, procyanidins, hydroxycinnamic acid derivatives, flavonols, and anthocyanins, were identified by HPLC-MS/MS and individually quantified using HPLC-DAD. Chlorogenic and neochlorogenic acids, procyanidins B1, B2, and B4, and some procyanidin trimers, quercetin 3-rutinoside, kaempferol 3-rhamnosyl-hexoside and quercetin 3-acetyl-hexoside, cyanidin 3-rutinoside, and 3-glucoside, were detected and quantified in the skin and flesh of the different cultivars. The total phenolics content, quantified as the addition of the individual compounds quantified by HPLC, ranged between 32.6 and 160.0 mg 100 g-1 of edible tissue. No correlation between the flesh color and the phenolic content of the different cultivars was observed., We are grateful to the Spanish CICYT (Comisión Interministerial de Ciencia y Tecnología) Projects AGL2001-1122-CO2-01 for financial support. D.R. is holder of a grant from Consejo Superior de Investigaciones Científicas (Reference I3P-BPD 2001-1).

10 pages, 6 figures, 1 table., The use of ozonated water as a sanitizer to extend the shelf life of fresh-cut lettuce and the effect on the antioxidant constituents (polyphenols and vitamin C) were investigated. Fresh-cut iceberg lettuce (Lactuca sativa L.) was washed at 4 °C using three different ozonated water dips [10, 20, and 10 activated by ultraviolet C (UV-C) light mg L-1 min total ozone dose], and the dips were compared with water and chlorine rinses. Treated lettuce was packaged in air or active modified atmosphere packaging (MAP) (4 kPa of O2 + 12 kPa of CO2 balanced with N2) and stored for 13 days at 4 °C. Despite its strong oxidizing activity, ozonated water did not stimulate the respiratory activity of fresh-cut lettuce. Moreover, ozonated water maintained the initial visual appearance of fresh-cut lettuce and controlled browning during storage in air. Initially, ozonated water and chlorine reduced the total mesophilic population by 1.6 and 2.1 log, respectively, when compared with water. Active MAP was effective in controlling total microbial growth, achieving 2.0 log reduction in relation to samples stored in air at the end of storage. On the other hand, active MAP caused a 2.0−3.5 reduction of coliforms on sanitized samples compared with water-washed samples. The most efficient treatments were ozone 20 and ozone 10 activated by UV-C, which were as effective as chlorine. Changes in individual phenolic compounds were independent of the washing treatments. In air, chlorogenic and isochlorogenic acid contents increased noticeably after 13 days while monocaffeoyltartaric and dicaffeoyltartaric acids remained unchanged. MAP effectively suppressed accumulation of caffeoylquinic derivatives, whereas caffeoyltartaric derivatives decreased during MAP storage to reach similar levels. The content of vitamin C (ascorbic acid and dehydroascorbic acid) decreased during storage, particularly under MAP. Ozonated water could be an alternative sanitizer to chlorine for fresh-cut lettuce due to good retention of sensorial quality and browning control with no detrimental reduction in the antioxidant constituents., We are grateful to Spanish CICYT (Comisión Interministerial de Ciencia y Tecnologia) Projects AGL2001-1269 and AGL2004-03060 for financial support. D.B. is the holder of a grant from the Ministerio de Ciencia y Tecnologia (Spain), reference BES-2002-0216.

7 pages, 6 figures, 1 table., l-Galactono-γ-lactone dehydrogenase (GLDH) activity and vitamin C content as ascorbic acid (AA) plus dehydroascorbic acid (DHA) were evaluated in five potato tuber cultivars (Agata, Altesse, Franceline, Manon, and Monalisa). The effect of fresh-cutting and subsequent refrigerated storage of Manon potato under different atmospheres (air, 20% CO2 + air, 100% N2, and vacuum packaging) on GLDH activity and vitamin C content was also determined. GLDH from the five potato tuber cultivars showed typical inhibition kinetics by high substrate concentration in the synthesis of AA from its physiological precursor l-galactonic acid-γ-lactone (GL). GLDH activity was not correlated with the corresponding vitamin C content in any potato tuber cultivar. GLDH from all the cultivars presented a major isoform with isoelectric point (IEP) 5, which changed to IEP = 4.3 after minimal processing. In addition, the GLDH-catalyzed synthesis of AA by the new isoform showed typical Michaelis kinetics, in which the enzyme became more efficient to catalyze the reaction. Whether the change in the isoform pattern was due to either post-translational modifications or de novo synthesis of a new isoenzyme remains unanswered. Fresh-cutting increased GLDH activity from 4.7-fold (vacuum packaging) to 11-fold (air) after 6 days. In addition, 100% of vitamin C content was retained in air and decreased in the rest of atmospheres after this storage period, following the sequence vacuum packaging (89%) > 100% N2 (78%) > 20% CO2 + air (63%). This tendency was correlated with the corresponding GLDH activity detected in each storage atmosphere, except in the case of 20% CO2 + air. Vacuum packaging proved to be the best storage condition, because fresh-cut potatoes did not turn brown and retained 89% of initial vitamin C content., This work has been partially supported by a grant from CICYT, Spain, project PTR 1995-0625OP. J. A. T. has a fellowship from Ministerio de Educación, Cultura y Deporte (Spain), reference AP2001-2493.

6 pages, 6 tables, 1 figure., Orange juice manufactured at industrial scale was subjected to digestion under in vitro gastrointestinal conditions (pH, temperature, and enzyme and chemical conditions) to evaluate the influence of individual industrial processing treatments on flavanone solubility, stability, and ability to permeate through a membrane under simulated physiological conditions. Four industrial processes including squeezing, standard pasteurization, concentration, and freezing were evaluated. Hand squeezing was compared with industrial squeezing. After in vitro gastrointestinal digestion of the orange juices, the flavanones able to permeate through a dialysis membrane, and those remaining in the retentate were evaluated by HPLC as were those present in the insoluble fraction. In all of the assayed orange juices, a high content of precipitated chalcones (≈70% of the total flavanones) was formed under the physiological conditions of the gastrointestinal tract. Hand squeezing provided a higher concentration of flavanones in the permeated fraction and lower transformation to chalcones than industrial squeezing. Standard pasteurization did not influence the solubility and permeability of the orange juice flavanones and chalcones. Industrial concentration did not affect the amount of flavanones able to permeate but decreased the chalcones produced. Juices produced from frozen orange juice contained considerably smaller amounts of both soluble flavanones and insoluble chalcones., The authors are grateful to the Fundación Seneca and Consejería de Agricultura, Agua y Medio Ambiente (AGR/6/FS/99), and the Spanish Comisio´n Interministerial de Ciencia y Tecnología (CICYT/AGL2001-1125) for their financial support of this work, and F.V. is indebted for a grant.