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Sunflower (Helianthus annuus L.) oil was coloured with pigments extracted from green leaves. Different amounts (0, 200, 400, 600, and 800 ppm) of oleoresin extracted from oregano (Origanum vulgare L.) as antioxidant, were added to the coloured oil. As controls, coloured oil without oleoresin (A.C.) and pure oil (A.P.) were used. The samples were stored at room temperature (10-20 ºC) in the dark for up to six months. During this time the oxidation of oleic acid, linoleic acid, peroxides index and the chlorophyll pigments were analized and the colour of the oil was determined. During the first month, only the ratio of chlorophyll to pheophytin changed, whereas all the other parameters stayed constant, independently to the amount of antioxidant added. Since among the treatments A.C. and A.P. not significant differences (p >0,05) were found, for oleic and linoleic methyl ester acids and peroxides index, it can be concluded that the edible, coloured sunflower oil shows an equivalent stability to the pure oil, when stored at darkness for three or six month. There was not observed an evident antioxidant action with the added oregano oleorresin to the coloured oil.Se estudió la estabilidad de aceite comestible de girasol (Helianthus annuus L.) de marca comercial sin antioxidantes, coloreado con pigmentos obtenidos de hojas verdes. Al aceite coloreado se adicionó oleorresina de orégano, como antioxidante, en cuatro concentraciones diferentes (200, 400, 600 y 800 ppm). Como controles, se utilizó aceite coloreado sin oleorresina (A.C.) y aceite puro (A.P.). Se almacenó en oscuridad y temperatura ambiente (10-20 ºC) por seis meses. Se evaluó la oxidación de lípidos (ésteres metílicos de ácidos oleico y linoleico e índice de peróxidos), pigmentos clorofílicos y color.El total de los pigmentos clorofilicos adicionados a las muestras de aceite comestible de girasol se mantuvo estable durante los tres primeros meses, evidenciándose sólo cambios en la proporción de clorofila a,b y feofitina a,b en el primer mes. Dado que no se encontraron diferencias significativas (p >0,05) entre los tratamientos A.P. y A.C., para ésteres metílicos de ácidos oleico y linoleico e índice de peróxidos, se podría concluir que el aceite comestible de girasol coloreado muestra una estabilidad equivalente al aceite puro, cuando es almacenado en oscuridad por tres o seis meses. No se observó un claro efecto de la acción antioxidante que tendría la oleorresina de orégano adicionada al aceite coloreado.

Purpose: Copper (Cu) contamination has been increasing in land ecosystems due to economic development activities. Excessive amount of Cu in soils is toxic to both plants and microorganisms. Biochar (BC) is known to immobilize soil Cu. The objectives of this research were to investigate the effects of chicken-manure-derived BC (CMB) on Cu immobilization, and growth of native metallophyte Oenothera picensis in a Cu-contaminated soil. Materials and methods: A Cu-contaminated sandy soil (338 mg Cu kg−1) was spiked and equilibrated with additional Cu (0, 100, and 500 mg Cu kg−1). The spiked soil was then amended with CMB (0, 5, and 10 % w/w) and incubated for 2 weeks. The metallophyte was grown on these treatments under greenhouse conditions for 3 months. Pore water solutions were collected from the plant pots every 30 days. After the harvest, soil and pore water pH, soil Cu fractions, pore water Cu concentration, soil microbial activity, plant biomass weight, and Cu concentration in plant parts were determined. Results and discussion: The CMB increased the pH of soils and soil pore water, and probably also soil major nutrients. It reduced the exchangeable fraction of Cu but increased its organic matter and residual fractions. At the same time, it decreased the Cu concentration in the soil pore water. The CMB increased basal respiration and dehydrogenase activity. The CMB application produced up to three and seven times more root and shoot biomass, respectively. In addition, shoots accumulated lesser Cu than control but roots did more. Plants survived in soil that was spiked with 500 mg Cu kg−1, only when CMB dose was 10 %. Conclusions: The CMB affected the Cu uptake in plant by altering the mobility, bioavailability, and spatial distribution of Cu in soils. The increase in available nutrients and decrease in Cu toxicity facilitated plant growth. The increased microbial activity probably also promoted the plant growth and reduced the Cu bioavailability. Therefore, CMB can be used to remediate Cu-contaminated soils. Refereed/Peer-reviewed