Influencia de las condiciones de conservación en el color del aceite de oliva virgen de la variedad "Arbequina". Aplicaciones de la colorimetría triestímulo en relación con otros parámetros de calidad

In this paper conservation, light and temperature conditions were studied over an eight month period to determine their effect on the physicochemical parameters of extra-virgin olive oil as well as the organoleptic traits and its colour. Olives in different stages of maturity were used. Triestimulus Colorimetry was applied as a possible objective measure of colour and, the predictive capacity of colorimetric parameters to determine the state of conservation was explored. Samples of four oils of the “Arbequina" variety were taken in various maturation stages. They were filtered and bottled in triplicate under three different conservation conditions: light and room temperature (transparent glass bottles), darkness and room temperature (opaque glass bottles wrapped in aluminium foil), darkness and sub-room temperature (opaque glass bottles kept at 5 degrees C). The following parameters were analyzed: acidity level, peroxide level, K270 and K232 coefficients, bitterness and stability levels, the organoleptic valuation, carotenoid and chlorophylic pigment and colour parameters by Triestimulus Colorimetry. Samples were taken each month. To begin with, a study was done of the physicochemical parameters and of the organoleptic traits under different conservation conditions. Results showed that, overtime, and independently of the conservation system, values varied inducing a quality devaluation. This was most notable in these oils which had been exposed to direct sunlight. The oils which had been kept at cooler temperature showed a greater proximity to the initial valuation. An envolving study of the chromatic parameters of the oils was done at the same time. The samples which had not been exposed to light showed an increase in clarity, a decrease in chromatic values or colour intensity and a lightening in hue. Towards the end of the study, appreciable visual differences in colour were observed in all cases. Especially in those exposed to light. Carotenoid pigment concentration decreased gradually in all cases and chlorophylic pigment underwent a brusque degradation in those samples which were exposed to light during the first month of conservation. A Multiple Lineal Regression study of the oils was done to determine, through Triestimulus Colorimetry, any possible statistical prediction of the elapse of time