Enzyme-mediated solvent extraction of carotenoids from marigold flower (Tagetes erecta)   总被引：2，自引：0，他引：2  

Barzana E  Rubio D  Santamaria RI  Garcia-Correa O  Garcia F  Ridaura Sanz VE  López-Munguía A 《Journal of agricultural and food chemistry》2002,50(16):4491-4496

Marigold flowers are the most important source of carotenoids for application in the food industry. However, the extraction gives almost 50% losses of the carotenoids depending on conditions for silaging, drying, and solvent extraction. In the past decades, macerating enzymes have been successfully applied to improve the extraction yield of valued compounds from natural products. In this work, an alternative extraction process for carotenoids is proposed, consisting of a simultaneous enzymatic treatment and solvent extraction. The proposed process employs milled fresh flowers directly as raw material, eliminating the inefficient silage and drying operations as well as the generation of hard to deal with aqueous effluents present in traditional processes. The process developed was tested at the 80 L scale, where under optimal conditions a carotenoid recovery yield of 97% was obtained.  相似文献   

Effects of pig slurry application on soils and soil humic acids     

Plaza C  Senesi N  García-Gil JC  Brunetti G  D'Orazio V  Polo A 《Journal of agricultural and food chemistry》2002,50(17):4867-4874

The effect of three annually consecutive additions of pig slurry at two rates (90 and 150 m3 x ha(-1) x year(-1) on soils and soil humic acids (HAs) was investigated in a field experiment under semiarid conditions. Soils and pig slurries were analyzed by standard methods. The HAs were isolated from soils and pig slurry by a conventional procedure based on alkaline extraction, acidic precipitation to pH 1, purification by repeated alkaline dissolutions and acidic precipitations, water washing, dialysis, and final freeze-drying. The HAs obtained were analyzed for elemental (C, H, N, S, and O) and acidic functional group (carboxylic and phenolic) composition, and by UV-vis, FT-IR, fluorescence, and ESR spectroscopies. With respect to the control soil, the pig slurry amended soils had greater pH and electrical conductivity, slightly larger total N content, and smaller values of C/N ratio. A decrease of total organic C was observed only in soils amended for 2 and 3 years at the higher slurry rate. With respect to control soil HA, pig slurry HA was characterized by larger contents of S- and N-containing groups, smaller acidic functional group and organic free radical contents, a prevalent aliphatic character, extended molecular heterogeneity, and smaller aromatic polycondensation and humification degrees. Amendment with pig slurry HA determines a number of modifications in soil HAs, including increase of C, S, and COOH contents, C/N ratios, and aliphaticity and decrease of extraction yields and N, O, phenolic OH, and organic free radical contents. These effects are generally more evident after the first year of slurry application and tend to disappear with increasing number of treatments. Most probably, over the years the slightly humified slurry HA is mineralized through extended microbial oxidation, whereas only the most recalcitrant components, such as S-containing, phenolic, and aliphatic structures, are partially accumulated by incorporation into soil HA.  相似文献   

Subcellular localization and isoenzyme pattern of peroxidase and polyphenol oxidase in beet root (Beta vulgaris L.)     

Escribano J  Gandía-Herrero F  Caballero N  Pedreño MA 《Journal of agricultural and food chemistry》2002,50(21):6123-6129

The two enzymes involved in enzymatic browning reactions, polyphenol oxidase (PPO) and peroxidase (PO), have been partially purified and extracted from different fractions of beet root. PPO is mainly located in the membrane fraction, and it was also found in the soluble fraction. In both cases PPO was in its latent state. However, PO activity was higher in the soluble fraction than in the membrane fraction. Nevertheless, the highest values of specific activity for PO were obtained from the solubilized enzyme from acetone powders. Under native isoelectric focusing (IEF), several PPO isoenzymes were present in the pH range of 4.8-5.8. All of these isoenzymes shared a single band with a similar apparent mass under sodium dodecyl sulfate-polyacrylamide gel electrophoresis. PO was also analyzed by IEF, showing a complex isoenzyme pattern in all fractions. The characteristic basic PO isoenzyme of high pI found in both the soluble fraction and the solubilized enzyme from acetone powders was not detected in the membrane fraction. The kinetic characterization of PPO and PO from all fractions was carried out.  相似文献   

Organic carbon content under different types of land use and soil in peninsular Spain   总被引：16，自引：0，他引：16  

Juan Carlos Rodríguez-Murillo 《Biology and Fertility of Soils》2001,33(1):53-61

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Formation of Amadori compounds in dehydrated fruits.     

M L Sanz  M D del Castillo  N Corzo  A Olano 《Journal of agricultural and food chemistry》2001,49(11):5228-5231

The presence of Amadori compounds in commercial dehydrated fruits has been shown through HPLC analysis of the corresponding 2-furoylmethyl-amino acids obtained by acid hydrolysis. Furosine (2-furoylmethyl-lysine) was the main 2-furoylmethyl derivative observed in dried figs and apricot samples, whereas in prunes and dates similar amounts of furosine and 2-furoylmethyl-gamma-aminobutyric acid were detected. A considerable variation of 2-furoylmethyl-amino acid contents among commercial raisin samples was observed. 2-Furoylmethyl-gamma-aminobutyric acid and 2-furoylmethyl-arginine, the most abundant 2-furoylmethyl-amino acids, ranged between 9.9 and 75.8 mg/100 g sample and 10.0 and 62.5 mg/100 g sample, respectively. Most of the Amadori compounds present in raisins seem to have originated during the commercial shelf life period rather than during processing. Determination of 2-furoylmethyl-amino acids could be used as a method of controlling commercial dehydrated fruit and selecting storage conditions.  相似文献   

Microbial community structure in forest soils treated with a fire retardant     

M. Díaz-Raviña  E. Bååth  A. Martín  T. Carballas 《Biology and Fertility of Soils》2006,42(6):465-471

The influence of a fire retardant (Firesorb, an acrylic–acrylamide copolymer) on the microbial community structure determined by phospholipid fatty acid (PLFA) analysis was examined under laboratory conditions using two different textured soils under pine forest. Firesorb was added to unheated and heated soil samples (350°C for 10 min followed by reinoculation, to mimic a forest fire) at three levels of application (none, usual and three times the usual levels), and measurements were made after 12 weeks of incubation. The relative importance of the three factors considered on the PLFA profiles was as follows: soil heating ≫ soil texture ≈ Firesorb treatment. In the unheated soils, Firesorb had a larger effect than soil texture, while the opposite was found in the heated soils. Soil heating reduced the total PLFAs, while Firesorb tended to increase them in both the unheated and heated soils. Soil heating decreased the PLFAs indicative of gram-positive (G⁺) bacteria and tended to increase the fatty acids associated with gram-negative (G⁻) bacteria and, to a lesser extent, the PLFA 18:2ω6, considered to be predominantly of fungal origin. Firesorb treatment decreased the G⁻/G⁺ bacteria ratio in the heated soils but tended to increase it in the unheated soils, the effect being dose dependent.  相似文献   

Heterogeneous aspects of lipid oxidation in dried microencapsulated oils     

Velasco J  Marmesat S  Dobarganes C  Márquez-Ruiz G 《Journal of agricultural and food chemistry》2006,54(5):1722-1729

This work was aimed at studying lipid oxidation in dried microencapsulated oils (DMOs) during long-term storage. Samples were prepared by freeze-drying of emulsions containing sodium caseinate and lactose as encapsulating components. Evaluation of lipid oxidation was approached by quantitative analysis of nonvolatile lipid oxidation products and tocopherol. Lipid oxidation products were analyzed by separation of polar compounds by adsorption chromatography followed by HPSEC with refraction index detection for quantitation of oxidized triglyceride monomers, dimers, and oligomers. The analytical method applied enabled the detection of different oxidative patterns between the free and encapsulated oil fractions. The free oil fraction of DMOs showed a typical oxidative pattern for oils in continuous phase, which consisted of a clear induction period, in which hydroperoxides (oxidized triglyceride monomers) accumulated, before oxidation accelerated. The end of the induction period was marked by the total loss of tocopherol and the initiation of polymerization. On the contrary, the encapsulated oil showed a pattern characteristic of a mixture of oils with different oxidation status. Thus, high contents of advanced oxidation compounds (polymerization compounds) were detected when the antioxidant (tocopherol) was still present in high amounts. It is concluded that the encapsulated oil was comprised of oil globules with very different oxidation status. The results obtained in this study gave evidence of heterogeneous aspects of lipid oxidation in a dispersed-lipid food system.  相似文献   

Use of Aloe vera gel coating preserves the functional properties of table grapes     

Serrano M  Valverde JM  Guillén F  Castillo S  Martínez-Romero D  Valero D 《Journal of agricultural and food chemistry》2006,54(11):3882-3886

Table grapes (Vitis vinifera L. cv. Crimson Seedless) were coated with Aloe vera gel according to our developed patent (SP Patent P200302937) and then stored for 35 days at 1 degrees C, and the subsequent shelf life (SL) was monitored at 20 degrees C. Uncoated clusters showed a rapid loss of functional compounds, such as total phenolics and ascorbic acid. These changes were accompanied by reduction of the total antioxidant activity (TAA) and increases in total anthocyanins, showing an accelerated ripening process. On the contrary, table grapes coated with Aloe vera gel significantly delayed the above changes, such as the retention of ascorbic acid during cold storage or SL. Consequently, Aloe vera gel coating, a simple and noncontaminating treatment, maintained the functional properties during postharvest storage of table grapes.  相似文献   

Purification of xylitol obtained by fermentation of corncob hydrolysates     

Rivas B  Torre P  Domínguez JM  Converti A  Parajó JC 《Journal of agricultural and food chemistry》2006,54(12):4430-4435

Hydrolysates obtained by autohydrolysis-posthydrolysis of corncobs were detoxified with charcoal, concentrated, supplemented with nutrients, and fermented with Debaryomyces hansenii. After biomass removal, the fermented media contained 0.1137 kg of nonvolatile components (NVC)/kg of liquor, which corresponded mainly to xylitol (0.6249 kg/kg of NVC) but also to minor amounts of inorganic components (measured as ashes), proteins, nonfermented sugars (xylose and arabinose), uronic acids, arabitol, and other nonvolatile components (ONVC). The media were subjected to further processing (sequential stages of adsorption, concentration, ethanol precipitation, concentration, and crystallization) to obtain food-grade xylitol. Adsorption experiments were carried out at various solid-to-liquor ratios. Under selected conditions (1 kg of charcoal/15 kg of liquors), the xylitol content increased to 0.6873 kg/kg of NVC, and almost total decoloration was achieved. The resulting liquor was concentrated by evaporation to increase its NVC content to 0.4032 kg/kg of liquor (corresponding to a xylitol concentration of 0.280 kg/kg of liquor), and ethanol was added to precipitate a part of the NVC (mainly proteins, but also uronic acids, ashes, and other nonvolatile compounds). Refined liquors (containing 0.7303 kg of xylitol/kg of NVC) were concentrated again, and ethanol was added (to reach 40-60% volume of the stream) to allow crystallization at -10 or -5 degrees C. Under selected conditions, 43.7% of xylitol contained in the initial fermentation broth was recovered in well-formed, homogeneous crystals, in which xylitol accounted for 98.9% of the total oven-dry weight. Material balances are presented for the whole processing scheme considered in this work.  相似文献   

Fluorescence, browning index, and color in infant formulas during storage     

Ferrer E  Alegría A  Farré R  Clemente G  Calvo C 《Journal of agricultural and food chemistry》2005,53(12):4911-4917

Free and total fluorescent compounds, browning index, and color formation were measured in milk-based powdered infant formulas (IF) during 2 years of storage at 20 and 37 degrees C. The excitation spectra from 415 nm emission show three peaks (ex lambda1 = 270 nm, lambda2 = 325/315 nm, lambda3 = 350 nm) and from 347 nm excitation two emission peaks (415 and 520 nm), and no wavelength shifts were observed. Temperature and time of storage exert in general no significant effect on the development of fluorescence emission intensity and browning index. However, an important increase in pentodilysine was recorded-probably because of the iron and ascorbic acid contents of the samples-as well as in browning index in adapted IF. In both IF a color increase (deltaE) throughout storage was observed, this increase being greater in samples stored at 37 degrees C than in those stored at 20 degrees C. The increase in color with time fitted a linear regression model. Color appeared to be an indicator of sufficient sensitivity to measure the effect of temperature or storage time.  相似文献