Efecto del choque térmico de arazá (eugenia stipitata me vaugh) sobre la tolerancia al frío

Los frutos de arazá (Eugenia stipitata) fueron cosechados en su madurez fisiológica y calentados a 50 °C durante O, 10, 20 ó 30 min antes de ser refrigerados a 7 °C durante 14 días y maduración complementaria a 25 °C durante 3 días

Extracción y medida de peroxidasa en pulpa de arazá (Eugenia stipitata MC Vaugh)

A technique for both extraction and activity measurement of peroxidase extracted from arazá (Eugenia stipitata Mc Vaugh) is described. Peroxidase from arazá pulp fruit was extracted using a combination of protein precipitation with acetone and extraction with 50 mM sodium buffer phosphate (pH 6.0). Optimum activity using guaiacol as H-donor was obtained at pH from 5.0 to 6.5, temperature from 60 to 75 °C, H2O2 between 10 to 15 mM and guaiacol from 80 to 160 mM. Thermal inactivation showed a first-order inactivation kinetic. Reactivation was observed when extracts were heated at 80 °C and afterwards incubated at 25 °C

Antioxidant capacity and total phenolic content of air-dried cape gooseberry (physalis peruviana l.) at different ripeness stages

Because the use of drying at high temperatures might negatively affect the functional properties of fruits, the effect of air-drying at 60°C on the total phenolic content (TPC) and antioxidant capacity (AOC) of cape gooseberry fruit was evaluated at three ripeness stages. The AOC was evaluated with 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), ferric reducing ability of plasma (FRAP), 1,1-diphenyl-2-picrylhydrazyl (DPPH), and β-carotene-linoleate assays. The TPC and AOC increased in the fresh fruit as the ripeness stage increased. The TPC increased from 401.8±19.8 to 569.3±22.3 mg GAE/100 g dry weight (DW). The AOC values obtained with ABTS in the fresh fruit (ranging from 79.4±4.5 to 132.7±12.9 µmol trolox/g fruit DW) were comparable to those obtained with FRAP (ranging from 82.9±16.3 to 153.9±31.7 µmol trolox/g fruit DW). The values assessed with DPPH ranged from 21.0±3.2 to 34.1±5.1 µmol trolox/g fruit DW. The β-carotene-linoleate assay gave values ranging from 5.8±1.1 to 12.7±2.0 µmol α-tocoferol/g fruit DW. Air-drying the cape gooseberry fruit had a small influence on the TPC. The air-dried fruit had AOC values ranging from 27 to 164% of the value of the fresh fruit. While the ABTS assay produced higher values in the air-dried fruit than in the fresh fruit, the FRAP, DPPH, and β-carotene-linoleate assays resulted in lower values in the air-dried fruit

Antioxidant capacity and total phenolic content of air-dried cape gooseberry (physalis peruviana l.) at different ripeness stages

Because the use of drying at high temperatures might negatively affect the functional properties of fruits, the effect of air-drying at 60°C on the total phenolic content (TPC) and antioxidant capacity (AOC) of cape gooseberry fruit was evaluated at three ripeness stages. The AOC was evaluated with 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), ferric reducing ability of plasma (FRAP), 1,1-diphenyl-2-picrylhydrazyl (DPPH), and β-carotene-linoleate assays. The TPC and AOC increased in the fresh fruit as the ripeness stage increased. The TPC increased from 401.8±19.8 to 569.3±22.3 mg GAE/100 g dry weight (DW). The AOC values obtained with ABTS in the fresh fruit (ranging from 79.4±4.5 to 132.7±12.9 µmol trolox/g fruit DW) were comparable to those obtained with FRAP (ranging from 82.9±16.3 to 153.9±31.7 µmol trolox/g fruit DW). The values assessed with DPPH ranged from 21.0±3.2 to 34.1±5.1 µmol trolox/g fruit DW. The β-carotene-linoleate assay gave values ranging from 5.8±1.1 to 12.7±2.0 µmol α-tocoferol/g fruit DW. Air-drying the cape gooseberry fruit had a small influence on the TPC. The air-dried fruit had AOC values ranging from 27 to 164% of the value of the fresh fruit. While the ABTS assay produced higher values in the air-dried fruit than in the fresh fruit, the FRAP, DPPH, and β-carotene-linoleate assays resulted in lower values in the air-dried fruit

Antioxidant capacity and total phenolic content of air-dried cape gooseberry (physalis peruviana l.) at different ripeness stages

Because the use of drying at high temperatures might negatively affect the functional properties of fruits, the effect of air-drying at 60°C on the total phenolic content (TPC) and antioxidant capacity (AOC) of cape gooseberry fruit was evaluated at three ripeness stages. The AOC was evaluated with 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), ferric reducing ability of plasma (FRAP), 1,1-diphenyl-2-picrylhydrazyl (DPPH), and β-carotene-linoleate assays. The TPC and AOC increased in the fresh fruit as the ripeness stage increased. The TPC increased from 401.8±19.8 to 569.3±22.3 mg GAE/100 g dry weight (DW). The AOC values obtained with ABTS in the fresh fruit (ranging from 79.4±4.5 to 132.7±12.9 µmol trolox/g fruit DW) were comparable to those obtained with FRAP (ranging from 82.9±16.3 to 153.9±31.7 µmol trolox/g fruit DW). The values assessed with DPPH ranged from 21.0±3.2 to 34.1±5.1 µmol trolox/g fruit DW. The β-carotene-linoleate assay gave values ranging from 5.8±1.1 to 12.7±2.0 µmol α-tocoferol/g fruit DW. Air-drying the cape gooseberry fruit had a small influence on the TPC. The air-dried fruit had AOC values ranging from 27 to 164% of the value of the fresh fruit. While the ABTS assay produced higher values in the air-dried fruit than in the fresh fruit, the FRAP, DPPH, and β-carotene-linoleate assays resulted in lower values in the air-dried fruit

Antioxidant capacity and total phenolic content of air-dried cape gooseberry (Physalis peruviana L.) at different ripeness stages Capacidad antioxidante y contenido total de fenoles de uchuva

ABSTRACT RESUMEN Because the use of drying at high temperatures might negatively affect the functional properties of fruits, the effect of air-drying at 60°C on the total phenolic content (TPC) and antioxidant capacity (AOC) of cape gooseberry fruit was evaluated at three ripeness stages. The AOC was evaluated with 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), ferric reducing ability of plasma (FRAP), 1, Air-drying the cape gooseberry fruit had a small influence on the TPC. The air-dried fruit had AOC values ranging from 27 to 164% of the value of the fresh fruit. While the ABTS assay produced higher values in the air-dried fruit than in the fresh fruit, the FRAP, DPPH, and β-carotene-linoleate assays resulted in lower values in the air-dried fruit. Debido a que el secado a altas temperaturas puede afectar negativamente las propiedades funcionales de las frutas, se evaluó el efecto del secado con aire a 60°C sobre el contenido total de fenoles (CTF) y la capacidad antioxidante (CAO) de frutos de uchuva en tres estados de madurez. CAO se evaluó por los métodos ácido 2,2'-azino-bis(3-etilbenzotiazolin-6-sulfonico) (ABTS), habilidad reductora de hierro en plasma (FRAP), 1,1-difenil-2-picrilhidrazil (DPPH) y β-caroteno-linoleato. En la fruta fresca los valores de CTF y CAO se incrementaron al aumentar el estado de madurez. CTF se incrementó desde 401,8±19,8 hasta 569,3±22,3 mg GAE/100 g peso seco, PS. Los valores de CAO obtenidos por ABTS en la fruta fresca (desde 79,4±4,5 hasta 132,7±12,9 µmol trolox/g fruta PS) fueron similares a los obtenidos por FRAP (desde 82,9±16,3 hasta 153,9±31,7 µmol trolox/g fruta PS). Los valores obtenidos por DPPH variaron entre 21,0±3,2 a 34,1±5,1 µmol trolox/g fruta PS. El ensayo de β-caroteno-linoleato arrojó valores entre 5,8±1,1 a 12,7±2,0 µmol α-tocoferol/g fruta PS. El secado con aire tuvo una influencia pequeña en los valores de CTF. La fruta seca tuvo valores de CAO que representaron entre 27 a 164% de los valores obtenidos en la fruta fresca, con valores mayores en la fruta seca que en la fresca para ABTS y valores menores para FRAP, DPPH y β-caroteno-linoleato

Effectiveness of sucrose during the frozen storage of arazá (eugenia stipitata mcvaugh) pulp

The effects of sucrose on the quality of frozen arazá pulp were investigated. Five levels of sucrose (0, 5, 10, 20, and 30%) were evaluated in combination with freezing at low speed, storage during one month, and thawing at two different speeds. Sensory quality and water loss after centrifugation (WLAC) were evaluated in the samples. Before freezing sucrose addition(5-30%) to the pulp did not affect the sensory quality of the samples, but a negative effect on WLAC at 5-10% sucrose was observed. Furthermore, addition of 20-30% sucrose to arazá pulp, in combination with low speed-freezing, frozen storage, and low-speed-thawing, can be a useful technique to preserve the texture of arazá pulp. The described treatment gave results comparable to those obtained for the fresh pulp and much better than those obtained when freezing was done at high speed

Estudio de la actividad enzimática poligaracturinasa en la corteza de pitaya amarilla (acanthocereus pitajaya)

Se determinó la actividad poligalacturonasa en corteza de pitaya amarilla (Acanthocereus pitajaya). El buffer fosfato de sodio 20 mM pH 7,0 con NaCl 0,5 M se constituyó en el sistema más efectivo para la extracción. Se obtuvieron valores óptimos de actividad a pH 5,0 en buffer citratos, a una temperatura de 40 °C. Los valores de KM y VMÁX hallados para esta enzima fueron 2,9 mg ácido poligalacturónico/ml y 0,076 nmol de azúcares reductores/s, respectivamente. Los resultados muestran que la poligalacturonasa está vinculada con el ablandamiento de este fruto.Polygalacturonase activity was determinated in yellow pitaya fruit (Acanthocereus pitajaya). Protein concentrations and activities of the enzyme in the extracts weredetermined. Buffer sodium phosphate 20 mM pH 7,0 with NaCl 0,5 M was the most effective extraction system. The enzyme exhibited optimum activity at pH 5,0 in buffer citrate at 40 °C. The KM of the enzyme was 2.9 mg/mL for polygalacturonic acid and VMÁX of 0.076 nmol of reducing groups/s. Results show that polygalacturonase is related with softening on yellow pitaya fruit

Búsqueda de las mejores condiciones para la extracción y medida de actividad de celulasa y xilanasa extraídas de la corteza de pitaya amarilla (acanthocereus pitajaya)

Para pitaya amarilla (Acanthocereus pitajaya) se ha encontrado que el ablandamiento excesivo de la cáscara contribuye al deterioro del fruto, al aplicar diferentes técnicas de conservación en fresco. Dado que tanto la celulasa como la xilanasa se han vinculado con el ablandamiento de la cáscara de frutos, este trabajo se basó en la búsqueda de las mejores condiciones de extracción y medida de actividad de celulasa y xilanasa. El mejor sistema de extracción fue buffer fosfato 20 mM, NaCl 0,5 M, pH 7,0. Para la medida de actividad de celulasa es necesario incubar durante 60 min a 37 ºC, con un volumen de extracto enzimático crudo de 30 µL, empleando buffer acetato 100 mM a pH 5,0; los valores de constante aparente de Michaelis Menten (KM aparente) y velocidad máxima (VMÁX) fueron 0,279 mg/mL y 0,00014 nmol glucosa/min, respectivamente. Para determinar la actividad de xilanasa se establecieron 15 min de tiempo de incuba-ción, a 50 ºC, empleando 30 µL de extracto enzimático crudo a pH 4,0 (buffer acetato 100 mM); los valores de KM aparente y VMÁX para xilanasa fueron 0,073 mg/mL y 0,0011 nmol glucosa/min, respectivamente

Extracción y medida de actividad de pectin metil estearasa en pitaya amarilla (acanthocereus pitajaya), enzima relacionada con el ablandamiento

RESUMENEn diversas técnicas aplicadas para la conservación en fresco de la pitaya amarilla (Acanthocereus pitajaya) se ha encontrado que el ablandamiento excesivo de su corteza contribuye al deterioro de su calidad. Puesto que pectinmetilestearasa (PME) se ha vinculado con el ablandamiento de frutos este estudio se desarrolló con el objeto de determinar el efecto de la incorporación de los aditivos tritón X-100, NaCl y cisteína en buffer fosfatos 20 mM pH 7,0 sobre la cantidad de proteína extraída y sobre la actividad de PME. También se evaluó la necesidad de recu-rrir al proceso de diálisis en buffer fosfatos 20 mM pH 7,0. En la medida de actividad se pusieron a punto el tiempo de incubación, la concentración del cofactor NaCl, pH, temperatura y concentración de sustrato (pectina cítrica). Se encontró que el mejor sistema de extracción fue el compuesto por buffer fosfato 20 mM, pH 7,0 con concen-traciones de NaCl que pueden estar entre 0,0 a 1,0 M. La medida de actividad se puede realizar empleando pectina cítrica entre 0,40 a 0,75%, a valores de pH entre 5,0 a 8,0, con incubación a una temperatura entre 40 a 45 °C, durante 2,5 min. Palabras claves: pectinmetilesterasa, pectina, ablandamiento, frutas, pitaya. ABSTRACT Using diverse techniques applied to keep the freshness of yellow pitaya (Acanthocereus pitajaya) fruit it has been found that excessive softening of its crust leads to quality deterioration. Since pectinmethyl esterase (PME) has been related to fruit softening in this study we evaluated the protein levels and the PME activity after the addition of Triton X-100 1% and NaCl in concentrations from 0 to 2 M in buffer 20 mM phosphate pH 7.0. Effects of cysteine addition and dialysis were also evaluated for the extraction Acta biol. Colomb., Vol. 14 No. 2, 2009 73 - 82 processes. Factors that can affect the activity of PME such as incubation time, different NaCl concentration, as value level of pH during the incubation, temperature and pectin (citric pectin) concentration were evaluated. The best system found in this study for PME extraction was buffer phosphate 20 mM, pH 7.0 and NaCl from 0.0 to 1.0 M. The best system for the activity measurement is to use pectin from 0.40 to 0.75%, keep the pH between 5 and 8 and incubate from 40 to 45 °C during 2.5 min. Key words: Pectinmetilesterase, pectin, softening, fruits, pitaya