Effect of processing and storage on the antioxidant ellagic acid derivatives and flavonoids of red raspberry (Rubus idaeus) jams     

Zafrilla P  Ferreres F  Tomás-Barberán FA 《Journal of agricultural and food chemistry》2001,49(8):3651-3655

From red raspberries, ellagic acid, its 4-arabinoside, its 4' (4' '-acetyl) arabinoside, and its 4' (4' '-acetyl)xyloside, as well as quercetin and kaempferol 3-glucosides, were identified. In addition, two unidentified ellagic acid derivatives were detected. The free radical scavenging activity of the ellagic acid derivatives was evaluated by using the DPPH method and compared to that of Trolox. All of the isolated compounds showed antioxidant activity. The effect of processing to obtain jams on raspberry phenolics was evaluated. The flavonol content decreased slightly with processing and more markedly during storage of the jams. The ellagic acid derivatives, with the exception of ellagic acid itself, remained quite stable with processing and during 6 months of jam storage. The content of free ellagic acid increased 3-fold during the storage period. The initial content (10 mg/kg of fresh weight of raspberries) increased 2-fold with processing, and it continued increasing up to 35 mg/kg after 1 month of storage of the jam. Then a slight decrease was observed until 6 months of storage had elapsed. The increase observed in ellagic acid could be explained by a release of ellagic acid from ellagitannins with the thermal treatment.  相似文献   

Postharvest induction modeling method using UV irradiation pulses for obtaining resveratrol-enriched table grapes: a new "functional" fruit?   总被引：4，自引：0，他引：4  

Cantos E  Espín JC  Tomás-Barberán FA 《Journal of agricultural and food chemistry》2001,49(10):5052-5058

A modeling method for the induction of resveratrol synthesis by UV irradiation pulses in Napoleon table grapes is proposed. The method is based on the combination of four main parameters: irradiation power (IW), irradiation time (IT), irradiation distance (ID), and number of elapsed days to achieve the highest resveratrol accumulation (D(m)). Maximum resveratrol content (11-fold higher than untreated grapes) was achieved using the combination: IW = 510 W, IT = 30 s, ID = 40 cm, and D(m) = 3 days. Sensory characteristics and main features of irradiated grapes (color, weight, firmness, flavor, size, ripening index and vitamin C content) remained unaltered after 1 week of storage. UV induction signal migrated to the hidden side of the grape skin with a delay of 3 days as compared to the directly irradiated side. Phenolic compounds were not detected in Napoleon grape flesh. Resveratrol content per standard serving (200 g) of irradiated grape was about 3 mg, an amount more than 10-fold higher than that of untreated Napoleon grapes. This means that a serving of irradiated grape (unpeeled) could supply the resveratrol content equivalent to 3 glasses of a red wine with high resveratrol content ( approximately 1 mg/glass). Therefore, controlled UV irradiation pulses are useful as a simple postharvest treatment (and alternative to genetic engineering) to obtain possible "functional" grapes (with enhanced health-promoting properties) as a dietary source of high resveratrol content.  相似文献   

Phytoextraction of Cd and Pb and physiological effects in potato plants (Solanum tuberosum var. Spunta): importance of root temperature.   总被引：1，自引：0，他引：1  

M Baghour  D A Moreno  G Víllora  J Hernández  N Castilla  L Romero 《Journal of agricultural and food chemistry》2001,49(11):5356-5363

Three consecutive years of field experiments were carried out to investigate the effect of different root-zone temperatures, induced by the application of mulches, on the concentration and accumulation of Cd and Pb and on bioindicators (chlorophylls, catalase, peroxidase and cell wall fractions) in different organs of potato plants (roots, tubers, stems, and leaflets). Four different plastic covers were employed (T1, transparent polyethylene; T2, white polyethylene; T3, white and black coextruded polyethylene, and T4, black polyethylene), using uncovered plants as the control (T0). The different treatments had a significant effect on the mean root-zone temperatures (T0 = 16 degrees C, T1 = 20 degrees C, T2 = 23 degrees C, T3 = 27 degrees C, and T4 = 30 degrees C) and induced significantly different responses in the Cd and Pb concentrations and phytoaccumulation, with T2 (23 degrees C) and T3 (27 degrees C) giving high concentrations of Cd in the roots and low concentrations in other organs. In relation to Pb, T2 and T3 reached higher levels in the tubers and lower levels in the roots, stems, and leaves. In terms of phytoaccumulation, the roots and tubers were the most effective organs for Cd and Pb. On the other hand, the highest values of peroxidase and catalase activities were obtained for T3. In addition, most of the carbohydrate fractions in both the roots and the tubers were highest for T3. Meanwhile, the lowest pigment values were registered for T1 (20 degrees C). For phytoremediation, it is necessary to ascertain the relevance and control of the thermal regime of the soil to optimize the phytoextraction of pollutant elements (Cd and Pb).  相似文献   

Oxidation of salsolinol by banana pulp polyphenol oxidase and its kinetic synergism with dopamine   总被引：1，自引：0，他引：1  

Sojo MM  Nuñez-Delicado E  Sánchez-Ferrer A  García-Carmona F 《Journal of agricultural and food chemistry》2000,48(11):5543-5547

Salsolinol, a tethrahydroisoquinoline present in banana and biosynthesized from dopamine, was oxidized by banana pulp polyphenol oxidase to its corresponding salsolinol-o-quinone. This oxidation was pH-dependent and showed a maximum at acidic pH values. At physiological pH of 5.0, the values obtained for the kinetic parameter (V(m) and K(m)) were 62.5 microM/min and 1.7 mM, respectively. When dopamine was added to the reaction medium to imitate physiological conditions, salsolinol was co-oxidized by dopamine-quinone. When this phenomenon was studied oxygraphically, an unexpected activation of dopamine oxidation was found in the presence of salsolinol. This activation was related with the enzyme's kinetic mechanism and was named "kinetic synergism", because a bad substrate activated a good one. A possible physiological role is discussed.  相似文献   

Cyclodextrins as activator and inhibitor of latent banana pulp polyphenol oxidase     

Sojo MM  Nuñez-Delicado E  García-Carmona F  Sánchez-Ferrer A 《Journal of agricultural and food chemistry》1999,47(2):518-523

The effect of cyclodextrins (CDs) on o-diphenol oxidation catalyzed by banana polyphenol oxidase (PPO) was studied. The oxidation of dopamine, the natural substrate of banana, in the presence of cyclodextrins was unaffected, because this hydrophilic phenol does not form inclusion complexes with CDs. However, when a hydrophobic phenol such as tert-butylcatechol (TBC) was used, a marked inhibition was observed with beta-, hydroxypropyl-beta-, and maltosyl-beta- CDs. This inhibition was due to the complexation of TBC in the CD core, demonstrating that banana pulp PPO worked only toward free substrate and not toward the complex TBC-CDs. In addition, the effect of some inhibitors in the presence of CDs and dopamine as substrate was studied. Increasing concentrations of CDs, in the presence of two inhibitors (4-iodophenol and cinnamic acid) were able to activate the inhibited enzyme to reach the noninhibited level by complexing the inhibitors in the hydrophobic core of the CDs. This dual effect of CDs as activator and inhibitor was tested in crude banana pulp extracts, with surprising activation effects never before described being observed.  相似文献   

Effect of postharvest storage and processing on the antioxidant constituents (flavonoids and vitamin C) of fresh-cut spinach   总被引：7，自引：0，他引：7  

Gil MI  Ferreres F  Tomás-Barberán FA 《Journal of agricultural and food chemistry》1999,47(6):2213-2217

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.  相似文献   

Simple and inexpensive flow L-glutamate determination using pumpkin tissue     

Arruda NJ  Filho JL  Montenegro MC  Araújo AN  Silva VL 《Journal of agricultural and food chemistry》2003,51(24):6945-6948

This work refers to a very easy to implementate flow injection system with potentiometric detection for l-glutamate determination in food samples. The proposed procedure is based on measurement of carbon dioxide produced by decarboxylation of l-glutamate catalyzed by l-glutamate decarboxylase (E.C. 4.1.1.1.5) from Cucurbita maxima (pumpkin). The FI potentiometric system includes an enzymatic reactor with a length of 8 cm and thickness of 5 mm packed with 200 mg of a C. maxima outer layer cut in to small pieces. The proposed procedure allowed l-glutamate determinations in the concentration interval of 10-100 mmol L(-1) for an injected sample volume of 50 microL. A phosphate buffer (0.1 mol L(-1), pH 5.5) solution flowing at 1.4 mL min(-1) was used as the carrier solution in the system. The results obtained in the analysis of food samples revealed a relative error lower than 5% when compared with those provided by the spectrophometric reference procedure. The immobilized reactor retained its initial activity for 21 days. It was possible to measure 40 samples/h with the flow system proposed.  相似文献   

FTIR study of glyphosate-copper complexes   总被引：4，自引：0，他引：4  

Undabeytia T  Morillo E  Maqueda C 《Journal of agricultural and food chemistry》2002,50(7):1918-1921

Complexes of the herbicide glyphosate (GPS) and the heavy metal Cu were studied by infrared spectroscopy under controlled pH, in order to know the mechanisms involved in the formation of these complexes. In CuGPS(-), the IR spectrum shows participation of the carboxylate and phosphonic moieties of the GPS molecule. The formation of the complex produces a lower symmetry in the phosphonate group because of loss of the resonance situation of PO(3)(2)(-) groups, with a subsequent split of their absorption bands. Carboxylate groups are participating by forming unidentate complexes. No conclusion is reached about the involvement of the amino group, but previous EPR findings indicate coordination of GPS to Cu via nitrogen. Consequently, glyphosate in this complex functions with a tridentate character by forming two chelate rings. A study of the CuGPSH species was not possible due to overlapping of its absorption bands with those of free GPS species.  相似文献   

Relationship between cyanogenic compounds in kernels, leaves, and roots of sweet and bitter kernelled almonds     

Dicenta F  Martínez-Gómez P  Grané N  Martín ML  León A  Cánovas JA  Berenguer V 《Journal of agricultural and food chemistry》2002,50(7):2149-2152

The relationship between the levels of cyanogenic compounds (amygdalin and prunasin) in kernels, leaves, and roots of 5 sweet-, 5 slightly bitter-, and 5 bitter-kernelled almond trees was determined. Variability was observed among the genotypes for these compounds. Prunasin was found only in the vegetative part (roots and leaves) for all genotypes tested. Amygdalin was detected only in the kernels, mainly in bitter genotypes. In general, bitter-kernelled genotypes had higher levels of prunasin in their roots than nonbitter ones, but the correlation between cyanogenic compounds in the different parts of plants was not high. While prunasin seems to be present in most almond roots (with a variable concentration) only bitter-kernelled genotypes are able to transform it into amygdalin in the kernel. Breeding for prunasin-based resistance to the buprestid beetle Capnodis tenebrionis L. is discussed.  相似文献   

Principal component analysis of biogenic amines and polyphenols in Hungarian wines   总被引：4，自引：0，他引：4  

Csomós E  Héberger K  Simon-Sarkadi L 《Journal of agricultural and food chemistry》2002,50(13):3768-3774

Biogenic amines, polyphenols, and resveratrol were analyzed quantitatively in 25 different Hungarian wines from the same wine-making region, harvest of 1998. Polyphenols were determined according to a spectrophotometric method, whereas other substrates were analyzed using overpressured-layer chromatography (OPLC). Principal component analyses (PCA) were performed on data matrices consisting of substrates (columns) and different sorts of wines (rows) from the region of Pécs (southern Hungary). It was found that four (unrotated) principal components account for >80% of the total variance in the data. The plots of component loadings showed significant groupings for concentrations of biogenic amines (and polyphenols). Similarly, the component scores grouped according to the different sorts of wines. The loading plots reveal that there is no need to measure all of the variables to achieve the same characterization. It is enough to measure one variable per group. Naturally, this conclusion is valid only within the limits of the present study; wines from other regions may behave differently.  相似文献