Advanced Search
Now showing items 1-10 of 99
Ácidos hidroxamicos cíclicos de gramíneas: distribución en la planta y efectos sobre la síntesis de adenosin-5 - trifosfatos en cloroplasto.
(Universidad de Chile., 1983)
Se analizó, mediante colorimetría el contenido de Hx en extractos etéreos de maíz LH rinconada. Se encontró desde niveles no detectables (< 3 mg/Kg TF) en frutos no germinados hasta sobre un 20 % del peso seco en nomófilos de 5 días....
The content of Hx in ethereal extracts of corn LH corner was analyzed by colorimetry. It was found from undetectable levels (< 3 mg/Kg TF) in non-germinated fruits up to 20% of the dry weight in 5-day-old nomophils....
The content of Hx in ethereal extracts of corn LH corner was analyzed by colorimetry. It was found from undetectable levels (< 3 mg/Kg TF) in non-germinated fruits up to 20% of the dry weight in 5-day-old nomophils....
Estudio de estabilidad química y organoléptica de una bebida analcóholica gasificada sabor naranja
(Universidad de ChilePrograma Cybertesis, 2006)
por medio de medición de pH y determinación de acidez titulable, el deterioro físico, por medio de colorimetría HunterLab y Munsell y el deterioro sensorial a través de panel de jueces entrenados y de panel de consumidores. En cada punto de toma de...
Geomorfología comparada entre las terrazas marinas separadas por el Valle del Maipo en San Antonio y Santo Domingo (Chile Central)
(2017)
muestreadas al norte del valle del río Maipo…………………26
Análisis de arena limo y arcilla al norte del valle del río Maipo…………………………………..27
Análisis estadístico de granulometría de arenas al norte del valle del río Maipo…………………28
Colorimetría de arenas al...
del río Maipo……………………39 Análisis de arena limo y arcilla de las muestras localizadas al sur del valle río Maipo…………...40 Análisis estadístico de granulometría de arenas al sur del valle del río Maipo................................42 Colorimetría de...
del río Maipo……………………39 Análisis de arena limo y arcilla de las muestras localizadas al sur del valle río Maipo…………...40 Análisis estadístico de granulometría de arenas al sur del valle del río Maipo................................42 Colorimetría de...
Efecto de la maduración de las olivas y heladas tempranas sobre la calidad química y organoléptica del aceite de oliva virgen extra
(Universidad de Chile, 2022)
, con una máquina modelo Frantoíno a 26±1°C. Los aceites se envasaron en frascos de vidrio color ámbar, y se congelaron a −23°C hasta su análisis. En los AOVEs se determinó: acidez libre, IP, K232, K270, colorimetría y tocoferoles según AOCS (1993); H...
Olive oil is the juice of the fruit of the olive tree (Olea europaea L.) extracted by mechanical processes and is the main source of fat in the Mediterranean diet. Its good valuation is due to the organoleptic and nutritional properties given by the profile of fatty acids, volatile and antioxidants compounds. The consumption of this oil has been associated with the decreased risk of cancer, cardiovascular and neurodegenerative diseases. The olive tree is resistant to low temperatures, until freezing causes damage to the cellular tissue. Another factor that affects olives is the degree of ripeness, since during this process changes in the chemical composition of the fruits are observed. The aim of this study was to evaluate the effects of frost and ripening stage on the quality of Arbequina extra virgin olive oil (EVOO). Physicochemical parameters of quality, antioxidants and volatile compounds in EVOO and glucose content in olive paste were evaluated. The olives were harvested for five months (from May to September), freezing half of each harvest in a refrigerator at −3±1°C for 12 hours. The oil was extracted from fresh and thawed olives with a Frantoíno model machine at 26±1°C. The oils were packed in amber glass bottles and frozen at −23°C until analysis. In the EVOOs it was determined: free fatty acid, PV, K232, K270, colorimetry and tocopherols according to AOCS (1993); H-ORACFL according to Prior et al., (2003), profile of phenols according to Mateos et al., (2001) and sensory evaluation of olive oils by an external service. Data were analyzed by ANOVA and Fisher's multiple comparisons intervals (LSD), principal component analysis and Partial Least Squares Discriminant Regression (PLS-DA). According to the quality parameters and the sensory evaluation conducted, the oils from fresh and frozen olives kept the category of extra virgin. An increase in PV and free fatty acid was seen as the maturation stage progressed. As the olives matured, the content of α-tocopherol and total phenolic compounds decreased significantly in oils from fresh and frozen olives. The first oleuropein derivative (3,4-DHPEA-EDA) predominated in frozen olive oils by the action of the enzyme β-glucosidase on oleuropein in freeze-damaged tissue. Oils from frozen olives presented a lower concentration of volatile compounds, and no significant differences (p>0,05) were found between ripening stages in AOVEs from fresh and frozen olives. The most abundant volatile compounds were (E)-2-hexenal, hexanal, (E)-2-hexenol and 1-hexanol. No significant differences (p>0,05) were seen in volatile compounds characteristic of frost between EVOOs from fresh and frozen olives. The PCA and PLS-DA models showed that there is a clear distinction between EVOOs from fresh and frozen olives, and between ripening stages. A negative correlation was found between glucose content and fat yield in Arbequina variety olive paste during ripening...
Olive oil is the juice of the fruit of the olive tree (Olea europaea L.) extracted by mechanical processes and is the main source of fat in the Mediterranean diet. Its good valuation is due to the organoleptic and nutritional properties given by the profile of fatty acids, volatile and antioxidants compounds. The consumption of this oil has been associated with the decreased risk of cancer, cardiovascular and neurodegenerative diseases. The olive tree is resistant to low temperatures, until freezing causes damage to the cellular tissue. Another factor that affects olives is the degree of ripeness, since during this process changes in the chemical composition of the fruits are observed. The aim of this study was to evaluate the effects of frost and ripening stage on the quality of Arbequina extra virgin olive oil (EVOO). Physicochemical parameters of quality, antioxidants and volatile compounds in EVOO and glucose content in olive paste were evaluated. The olives were harvested for five months (from May to September), freezing half of each harvest in a refrigerator at −3±1°C for 12 hours. The oil was extracted from fresh and thawed olives with a Frantoíno model machine at 26±1°C. The oils were packed in amber glass bottles and frozen at −23°C until analysis. In the EVOOs it was determined: free fatty acid, PV, K232, K270, colorimetry and tocopherols according to AOCS (1993); H-ORACFL according to Prior et al., (2003), profile of phenols according to Mateos et al., (2001) and sensory evaluation of olive oils by an external service. Data were analyzed by ANOVA and Fisher's multiple comparisons intervals (LSD), principal component analysis and Partial Least Squares Discriminant Regression (PLS-DA). According to the quality parameters and the sensory evaluation conducted, the oils from fresh and frozen olives kept the category of extra virgin. An increase in PV and free fatty acid was seen as the maturation stage progressed. As the olives matured, the content of α-tocopherol and total phenolic compounds decreased significantly in oils from fresh and frozen olives. The first oleuropein derivative (3,4-DHPEA-EDA) predominated in frozen olive oils by the action of the enzyme β-glucosidase on oleuropein in freeze-damaged tissue. Oils from frozen olives presented a lower concentration of volatile compounds, and no significant differences (p>0,05) were found between ripening stages in AOVEs from fresh and frozen olives. The most abundant volatile compounds were (E)-2-hexenal, hexanal, (E)-2-hexenol and 1-hexanol. No significant differences (p>0,05) were seen in volatile compounds characteristic of frost between EVOOs from fresh and frozen olives. The PCA and PLS-DA models showed that there is a clear distinction between EVOOs from fresh and frozen olives, and between ripening stages. A negative correlation was found between glucose content and fat yield in Arbequina variety olive paste during ripening...
Efecto del déficit de irrigación y fertilización potásica en el potencial impacto del fenómeno de heladas sobre la calidad del aceite de oliva virgen extra variedad ‘arbequina’
(Universidad de Chile, 2023)
aceites se determinó acidez libre, índice de peróxidos, coeficientes de extinción específicos y tocoferoles según metodología AOCS (1993), colorimetría (ISO 11664-4:2011; Norma UNE 72031/83), perfil de volátiles (Romero, N. y cols., 2015), perfil de...
Olive oil is an essential component in the diet of many people, due to its nutritional and functional properties, granted mainly by the profile of fatty acids and minor components such as phenolic compounds, which together with volatile compounds provide the organoleptic qualities responsible for the flavor of the oil, highly valued by consumers. In recent years, the demand for this product has increased, promoting olive plantations in higher latitude areas. Even the olive tree is highly cold-tolerant, the influence of low temperatures can cause the phenomenon of early frost, which affects the quality of EVOO. Deficit irrigation and potassium fertilization of the soil have been studied as cultivation strategies that could attenuate the damage caused by early frosts that affect olives, through the accumulation of solutes and bioactive compounds, making them much more tolerant and resistant to frost, and also to advance the ripening process before the occurrence of frosts. The aim of this study was to evaluate the effect of deficit irrigation and potassium fertilization as a way to increase the osmotic capacity of 'Arbequina' olives, on the potential impact of frost on the quality of extra virgin olive oil and its bioactive compounds. 'Arbequina' olives were harvested at three stages of ripening (May to July) during 2021. Half of the harvest was submitted to forced freezing for 7 h at -3 ± 1°C before oil extraction, while the other half had its oil extracted immediately. Sugars were determined in the olive pulp by HPLC. In the oils, free acidity, peroxide value, specific extinction coefficients and tocopherols were determined according to AOCS methodology (1993), colorimetry (ISO 11664-4:2011; Standard UNE 72031/83), volatile compounds (Romero, N. et al., 2015), phenolic compounds (Fuentes et al., 2018) and antioxidant capacity (Huang et al., 2002). Data were analyzed using ANOVA and Fisher’s Multiple Comparison Interval LSD. A second-order model was fitted to the data using Box-Behnken Design (BBD) and relationships and correlations were studied through multivariate analysis (PCA and OPLS-DA). All the oil samples analyzed in the laboratory, both from fresh and frozen olives, remained within the limits established by the IOC standard, so they were classified as EVOOs. The oils from frozen olives showed a lower peroxide value and were also more luminous, greener, and yellower. Samples with higher irrigation had a higher content of volatile compounds, and, in early stages of maturation, the samples showed a lower content of phenolic compounds. This behavior was more pronounced in oils from fresh olives. The combined effect of irrigation and potassium fertilization allowed frozen olive oils to maintain their quality compared to fresh olive oils, as evidenced by the values of quality parameters, tocopherol content, antioxidant capacity and the absence of volatile compounds responsible for the defect caused by early frosts. Funding: ANID Fondecyt Project 1191682....
Olive oil is an essential component in the diet of many people, due to its nutritional and functional properties, granted mainly by the profile of fatty acids and minor components such as phenolic compounds, which together with volatile compounds provide the organoleptic qualities responsible for the flavor of the oil, highly valued by consumers. In recent years, the demand for this product has increased, promoting olive plantations in higher latitude areas. Even the olive tree is highly cold-tolerant, the influence of low temperatures can cause the phenomenon of early frost, which affects the quality of EVOO. Deficit irrigation and potassium fertilization of the soil have been studied as cultivation strategies that could attenuate the damage caused by early frosts that affect olives, through the accumulation of solutes and bioactive compounds, making them much more tolerant and resistant to frost, and also to advance the ripening process before the occurrence of frosts. The aim of this study was to evaluate the effect of deficit irrigation and potassium fertilization as a way to increase the osmotic capacity of 'Arbequina' olives, on the potential impact of frost on the quality of extra virgin olive oil and its bioactive compounds. 'Arbequina' olives were harvested at three stages of ripening (May to July) during 2021. Half of the harvest was submitted to forced freezing for 7 h at -3 ± 1°C before oil extraction, while the other half had its oil extracted immediately. Sugars were determined in the olive pulp by HPLC. In the oils, free acidity, peroxide value, specific extinction coefficients and tocopherols were determined according to AOCS methodology (1993), colorimetry (ISO 11664-4:2011; Standard UNE 72031/83), volatile compounds (Romero, N. et al., 2015), phenolic compounds (Fuentes et al., 2018) and antioxidant capacity (Huang et al., 2002). Data were analyzed using ANOVA and Fisher’s Multiple Comparison Interval LSD. A second-order model was fitted to the data using Box-Behnken Design (BBD) and relationships and correlations were studied through multivariate analysis (PCA and OPLS-DA). All the oil samples analyzed in the laboratory, both from fresh and frozen olives, remained within the limits established by the IOC standard, so they were classified as EVOOs. The oils from frozen olives showed a lower peroxide value and were also more luminous, greener, and yellower. Samples with higher irrigation had a higher content of volatile compounds, and, in early stages of maturation, the samples showed a lower content of phenolic compounds. This behavior was more pronounced in oils from fresh olives. The combined effect of irrigation and potassium fertilization allowed frozen olive oils to maintain their quality compared to fresh olive oils, as evidenced by the values of quality parameters, tocopherol content, antioxidant capacity and the absence of volatile compounds responsible for the defect caused by early frosts. Funding: ANID Fondecyt Project 1191682....
La suplementación con zinc reduce la concentración de ácidos grasos libres en pacientes con diabetes tipo 2
(Soc. Chilena Nutrición, 2020)
pacientes con DT2 el efecto de 24 meses
de suplementación con zinc sobre las concentraciones
séricas de AGL en ayuno. Para este propósito: se realizó la
determinación de AGL en ayuno por colorimetría enzimá-
tica, zinc plasmático por espectrofotometría de...
radioinmunoensayo (Siemens Healthcare Diagnostics Inc., Los Angeles, CA, USA). La glucosa, colesterol total, colesterol de HDL, y triglicéridos fueron determinados por colorimetría de punto final (DIALAB GmbH, Wr. Neudorf, Austria), y se calculó el colesterol de...
radioinmunoensayo (Siemens Healthcare Diagnostics Inc., Los Angeles, CA, USA). La glucosa, colesterol total, colesterol de HDL, y triglicéridos fueron determinados por colorimetría de punto final (DIALAB GmbH, Wr. Neudorf, Austria), y se calculó el colesterol de...
Estudio geoquímico ambiental y mapa de riesgos de la Cuenca del río Huasco, III Región de Atacama, Chile
(Universidad de Chile, 2017)
Evaluación de dos estrategias de pigmentación en salmón coho (Oncorhynchus kisutch)
(Universidad Austral de Chile, 2005)
coloración de los steaks y filetes evaluada mediante colorimetría de refractancia está
representada por los valores de a* correspondiente a la cromaticidad rojo-verde (Minolta CR-
200) (cuadro 5). Los valores presentados tanto por los steaks como por los...
medición por colorimetría de refractancia demuestra claramente que cuando se incrementa el contenido de astaxantina en el músculo, el valor de a* aumenta. Sin embargo, la pigmentación determinada en este trabajo fue menor a los 16-18 ppm de astaxantina...
medición por colorimetría de refractancia demuestra claramente que cuando se incrementa el contenido de astaxantina en el músculo, el valor de a* aumenta. Sin embargo, la pigmentación determinada en este trabajo fue menor a los 16-18 ppm de astaxantina...
Variación de materia orgánica del suelo en ecosistemas esclerófilos con diferentes grados de perturbación antrópica en la Reserva nacional Roblería del Cobre de Loncha, Región Metropolitana
(Universidad de Chile, 2013)
por calcinación a 650 ºC. El CAH y CAF se determinaron mediante el
método de Kononova y colorimetría según Rheim Ulrich. El mayor porcentaje de materia
orgánica (13,75%) se encontró bajo P en la fracción fina del suelo y en el rango de
profundidad 0...
extraíble. 14 Luego se procedió a la purificación de las fracciones (ácidos húmicos y ácidos fúlvicos), posteriormente el carbono húmico y carbono fúlvico se determinó por colorimetría de acuerdo al método de Rhiem Ulrich, utilizando un...
extraíble. 14 Luego se procedió a la purificación de las fracciones (ácidos húmicos y ácidos fúlvicos), posteriormente el carbono húmico y carbono fúlvico se determinó por colorimetría de acuerdo al método de Rhiem Ulrich, utilizando un...
Variación de materia orgánica del suelo en ecosistemas esclerófilos con diferentes grados de perturbación antrópica en la Reserva nacional Roblería del Cobre de Loncha, Región Metropolitana
(Universidad de Chile, 2013)
por calcinación a 650 ºC. El CAH y CAF se determinaron mediante el
método de Kononova y colorimetría según Rheim Ulrich. El mayor porcentaje de materia
orgánica (13,75%) se encontró bajo P en la fracción fina del suelo y en el rango de
profundidad 0...
extraíble. 14 Luego se procedió a la purificación de las fracciones (ácidos húmicos y ácidos fúlvicos), posteriormente el carbono húmico y carbono fúlvico se determinó por colorimetría de acuerdo al método de Rhiem Ulrich, utilizando un...
extraíble. 14 Luego se procedió a la purificación de las fracciones (ácidos húmicos y ácidos fúlvicos), posteriormente el carbono húmico y carbono fúlvico se determinó por colorimetría de acuerdo al método de Rhiem Ulrich, utilizando un...