Showing papers by "Francisco J. Heredia published in 2009"

Separation of structural, geometrical and optical isomers of epoxycarotenoids using triacontyl-bonded stationary phases.

Abstract: The efficiency of C 30 stationary phases in the separation of carotenes and diverse hydroxycarotenoids has been the subject of several studies. However, little is known concerning their ability to resolve epoxycarotenoids isomers, whose study is of great importance due to the functions they serve and the information they can reveal concerning the processing of foods. We have concluded that C 30 columns provide an excellent separation of structural, geometrical and optical isomers of epoxycarotenoids and that the presence of 5,8-epoxide groups leads to a better shape recognition, to the extent that over 10 geometrical-optical isomers of 5,8-epoxycarotenoids have been separated. Additionally, it was observed that these carotenoids elute later than their 5,6-epoxide counterparts, albeit the latter have a longer chromophore.

Color Measurements in Blue-Tinted Cups for Virgin-Olive-Oil Tasting

Abstract: Color measurements have been performed using eighteen virgin-olive-oil tasting cups with ten different commercial virgin olive oils, positioned in a color cabinet with a D65 source. Three geometries (spectroradiometer tilted 0°, 30°, and 60°) were employed, simulating different positions of the taster’s eye. Our main goal was to test whether traditional blue-tinted cups effectively conceal the color of virgin olive oils, as desired in sensorial analyses. None of the cups employed had all their geometrical dimensions within the standardized values, despite being cups used in official sensorial analyses. Measuring a magnitude similar to the spectral transmittance, we found substantial differences among the glasses of the eighteen tasting cups. Comparing color variability for one virgin olive oil in different tasting cups, and one tasting cup with different virgin olive oils, we discovered that: (1) variability was higher in the case of one virgin olive oil in different cups; (2) in both cases the variability increased with the tilt of the spectroradiometer; (3) even when the variability was lowest (i.e., 0° measurements for two oils in the same cup), the average color difference was above typical visual thresholds in simultaneous comparison experiments. In the most usual case of a successive comparison between two oils in the same tasting cup, it is expected that in most cases tasters will perceive color differences between the oils when their eyes are tilted 60° with respect to the horizontal, but not when they observe the cup in the horizontal direction. In summary, blue-tinted olive-oil-tasting cups reduce, but do not completely conceal, oil color. The use of opaque tasting cups with black walls is suggested.

Optimization of olive-fruit paste production using a methodological proposal based on a sensory and objective color analysis

Abstract: This paper deals with the optimization of the conditions to formulate paste based on olive fruits. The processing stages included: washing, blending, oil addition and preservation. Pair-comparisons and ranking tests were carried out by both a trained panel and a consumer panel to single out the preferred sample at each stage. The sensory attributes considered were taste, visual texture, texture in the mouth and overall preference. The results of the sensory analyses were processed statistically by means of ANOVA and the Friedman test to select the most appropriate processing conditions: washing for 30 minutes three times, blending at 2000 r.p.m, and the addition of 10 mL of oil. Several pasteurization conditions were assayed (62.5, 75, 85 and 95 °C for 15 minutes). No significant color differences (p < 0.05) were found for the objective color measurement (CIELAB) of the pastes submitted to the different pasteurization conditions. Based on the results of the preference test, the pasteurization conditions selected were heating at 85 °C for 15 minutes