Physicochemical and digestibility properties of double-modified banana ( Musa paradisiaca L.) starches     

Carlos-Amaya F  Osorio-Diaz P  Agama-Acevedo E  Yee-Madeira H  Bello-Pérez LA 《Journal of agricultural and food chemistry》2011,59(4):1376-1382

Banana starch was chemically modified using single (esterification or cross-linking) and dual modification (esterification-cross-linking and cross-linking-esterification), with the objective to increase the slowly digestible starch (SDS) and resistant starch (RS) concentrations. Physicochemical properties and in vitro digestibility were analyzed. The degree of substitution of the esterified samples ranged from 0.006 to 0.020. The X-ray diffraction pattern of the modified samples did not show change; however, an increase in crystallinity level was determined (from 23.79 to 32.76%). The ungelatinized samples had low rapidly digestible starch (RDS) (4.23-9.19%), whereas the modified starches showed an increase in SDS (from 10.79 to 16.79%) and had high RS content (74.07-85.07%). In the cooked samples, the esterified starch increased the SDS content (21.32%), followed by cross-linked starch (15.13%). Dual modified starch (cross-linked-esterified) had the lowest SDS content, but the highest RS amount. The esterified and cross-linked-esterified samples had higher peak viscosity than cross-linked and esterified-cross-linked. This characteristic is due to the fact that in dual modification, the groups introduced in the first modification are replaced by the functional group of the second modification. Temperature and enthalpy of gelatinization decreased in modified starches (from 75.37 to 74.02 °C and from 10.42 to 8.68 J/g, respectively), compared with their unmodified starch (76.15 °C and 11.05 J/g). Cross-linked-esterified starch showed the lowest enthalpy of gelatinization (8.68 J/g). Retrogradation temperature decreased in modified starches compared with unmodified (59.04-57.47 °C), but no significant differences were found among the modified samples.  相似文献   

Serological and molecular detection of <Emphasis Type="Italic">Mycobacterium avium</Emphasis> subsp. <Emphasis Type="Italic">paratuberculosis</Emphasis> in cattle of dairy herds in Colombia     

Fernández-Silva JA  Abdulmawjood A  Akineden O  Bülte M 《Tropical animal health and production》2011,43(8):1501-1507

The objective of this study is the detection of Mycobacterium avium subsp. paratuberculosis (MAP) by serum enzyme-linked immunosorbent assay (ELISA), fecal polymerase chain reaction (PCR), and fecal culture in Colombian dairy herds. Serum and fecal samples from asymptomatic cows (n = 307) of 14 dairy herds were tested for MAP by an unabsorbed ELISA test (ELISA-A). Serum and fecal samples from positive ELISA-A animals (n = 31) were further tested by an absorbed ELISA test (ELISA-B) and PCR. Fecal samples from animals of herds positive by ELISA-A and PCR (n = 105) were inoculated onto three different culture media. ELISA-A produced positive results in 10% of the serum samples and 71% of the herds. ELISA-B and PCR results were positive in two and six serum and fecal samples from positive ELISA-A animals, respectively. Fecal samples were negative for MAP on all culture media. The results of this study confirmed the presence of MAP in local dairy herds and the difficulties of MAP detection in asymptomatic animals by ELISA, PCR, and fecal culture.  相似文献   

COMPUTED TOMOGRAPHIC ANATOMY OF THE CANINE INNER AND MIDDLE EAR     

Marco  Russo  DVM  PHD  Eucenio M.  Covelli  MD  Leonardo  Meomartino  DVM  PHD  Christopher R.  Lamb  MA  Vetmb  Arturo Brunetti  MD 《Veterinary radiology & ultrasound》2002,43(1):22-26

A series of high-resolution computed x-ray tomography (CT) images of the normal canine middle and inner ear are presented to serve as a reference for optimal interpretation of clinical CT images of animals with diseases affecting this region.  相似文献   

A Procedure for Choosing Tree-Stem Volume Equations Previously Fitted in a Forest     

Arturo A. Alvarado-Segura  Karen I. De La Cruz-De La Cruz 《Journal of Sustainable Forestry》2020,39(6):595-607

ABSTRACT

Tree-stem volumes constitute critical measurements for forest management. We propose a general two-criterion procedure for choosing the most reliable and robust volume equation(s), among a set of them previously fitted in a forest. Also, the proposal can be used as an additional criterion when fitting new equations to a single sample. Through simulated volumes, we considered how well a model estimates the volume generated by itself (the more accurate estimation, the better) and measured a model’s variability of the mean errors when it estimates volumes rebuilt by other models (the lower variability, the better). The procedure is exemplified with volume equations of Pinus patula in the Forestry Management Unit 1302 in Hidalgo, Mexico. In the example, we found that a linearized form of the combined-variable equation results reliable and robust. This selection coincided with the one made with data of a recent 150 trees sample (validation), where the rebuilt-estimated mean volume differs 0.034 m3 from the observed mean volume; it represents around US$2.6. Therefore, it is shown that simulation becomes an effective tool to identify equations that do not reproduce the volume of trees well in the current forest and helps to choose reliable and robust equations.  相似文献   

Simultaneous fluorometric determination of chlorophylls a and B and pheophytins a and B in olive oil by partial least-squares calibration     

Galeano Díaz T  Durán Merás I  Correa CA  Roldán B  Rodríguez Cáceres MI 《Journal of agricultural and food chemistry》2003,51(24):6934-6940

The resolution of quaternary mixtures of chlorophylls a and b and pheophytins a and b has been accomplished by partial least-squares (PLS) multivariate calibration, applied to the fluorescence signals of these pigments. The total luminescence information of the compounds has been used to optimize the spectral data set to perform the calibration. After preliminary studies, a method is described in acetone media, to avoid emulsions with the olive oil samples. Different scanning paths have been selected for each method. For the simultaneous determination of the pigments in olive oil samples, a comparative study of the results found by using excitation, emission, and synchronous spectral data, as analytical signal, was performed. The excitation spectra were selected as the better analytical signals for the determination of the pigments in olive oil samples. The optimum wavelength range to record the excitation spectra (lambda(em) = 662 nm) was selected to minimize the contribution of pheophytin a and to maximize the contribution of the other pigments, which are the minor constituents in olive oil. Determination of these pigments in olive oil samples was effected from the excitation spectra of dissolutions o suitable aliquots in acetone. Recovery values from olive oil, spiked with chlorophylls a and b and pheophytins a and b, were in the ranges of 70-112, 71-111, 76-105, and 82-109%, respectively.  相似文献   

Seasonal distribution of air-borne pathogenic and free-living amoebae in Mexico City and its suburbs     

Dr. Fermin Rivera  Patricia Bonilla  Elizabeth Ramirez  Arturo Calderon  Elvia Gallegos  Salvador Rodriguez  Ricardo Ortiz  Dolores Hernandez  Victor Rivera 《Water, air, and soil pollution》1994,74(1-2):65-87

A survey was carried out over a one-year period to isolate amoebae suspended in the air of Mexico City and its suburbs. Sampling stations were placed at the four cardinal points of the metropolitan area. Selective media were used to culture the amoebae isolated. Specialized taxonomic keys and physical and physiological tests were used for identification, and a statistical analysis was performed to determine the correlations between physico-chemical and biological parameters. 108 strains were isolated, of which 19 were pathogenic via intracerebral inoculation and 9 via intranasal inoculation. Species of the generaAcanthamoeba, Vahlkampfia andHartmannella were most abundant.Acanthamoeba polyphaga showed the highest abundance. Several times during the period of the study SO₂ O₃, CO, NO and NO₂ exceeded the permissible levels established by the Mexican government. The ability of amoebae to form cysts and cyst size were important factors for their presence, survival, abundance and diversity in the atmosphere. The main source of air-borne amoebae was the soil. Factors that favored the incidence and diversity of the isolates were wind speed and direction, low relative humidity, generation of frequent dust-storms, resuspension of amoebae by vehicular traffic, proximity to garbage dumps and large extensions of bare soil. Soil cover was a factor associated with a reduction in the incidence and diversity of the aerial amoebae. This study demonstrates that there are viable cysts of amoebae in the atmosphere of Mexico City, that may have potential importance in the case of certain kinds of human allergies and diseases. Further research is needed to find out the aerial presence of viable cysts of obligatory, amphizoic or opportunistic amoebic parasites, and to clarify the qualitative and quantitative effects of the local meteorological and physico-chemical environment on the free-living amoebae present in the atmosphere.  相似文献   

Indirect biomass estimations in Collembola     

Marian Caballero  Enrique Baquero  Arturo H. Ario  Rafael Jordana 《Pedobiologia》2004,48(5-6):551-557

We propose coefficients for regressions relating dry weight to body or tergite length in Folsomia candida, Entomobrya schoetti, Sminthurus viridis, and Hypogastrura vernalis (Collembola). Measurements were made on large batches of preserved, identified specimens. Batches were dessicated completely by critical-point drying and weighed. We compare our data with other published models and critically review the literature, finding questionable records.  相似文献   

The Endemic Copepod Calanus pacificus californicus as a Potential Vector of White Spot Syndrome Virus     

Fernando Mendoza-Cano  Arturo Sánchez-Paz  Berenice Terán-Díaz  Diego Galván-Alvarez  Trinidad Encinas-García  Tania Enríquez-Espinoza 《Journal of aquatic animal health》2013,25(2):113-117

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Antioxidant activity of Rhizophora mangle bark     

Sánchez J  Melchor G  Martínez G  Escobar A  Faure R 《Fitoterapia》2006,77(2):141-143

The antioxidant activity of Rhizophora mangle bark aqueous extract and its majoritary component and high molecular weight polyphenols' fraction were studied using deoxyribose assay. The total extract and its fraction showed scavenging activity of hydroxyl radicals and hability to chelate iron ions.  相似文献   

Alkyl esters of fatty acids a useful tool to detect soft deodorized olive oils     

Pérez-Camino Mdel C  Cert A  Romero-Segura A  Cert-Trujillo R  Moreda W 《Journal of agricultural and food chemistry》2008,56(15):6740-6744

Fatty acid alkyl esters (FAAEs) are a family of natural neutral lipids present in olive oils and formed by esterification of free fatty acids (FFAs) with low molecular alcohols. Inappropriate practices during the olive oil extraction process and bad quality of the olive fruits promote their formation. Quantification can be done by isolation with a silica gel solid phase extraction cartridge followed by analysis on a gas chromatograph equipped with a programmed temperature vaporizer injector using a polar capillary column. The application of the method to more than 100 Spanish olive oils from different categories, varieties, and geographical origin allowed for establishing the average content of FAAEs and distinguishing the Spanish protected denomination of origin (PDO) and extra virgin olive oils from other categories of olive oils. Those other categories of oils can be subjected to a mild refining process, which leads to blending with extra virgin olive oils. Studies on low quality oils subjected to mild refining showed that FAAEs remain after that process. Thereby, blends of extra virgin olive and mildly refined low quality olive oils can be detected by their alkyl ester concentrations.  相似文献