Showing papers by "Francisco J. Heredia published in 2011"

Effects of salinity stress on carotenoids, anthocyanins, and color of diverse tomato genotypes.

Abstract: One nonanthocyanin-accumulating (Ailsa Craig) and three anthocyanin-accumulating tomato genotypes (Anthocyanin fruit type, Atroviolaceum, and Sun Black) were analyzed to assess differences in their carotenoid and anthocyanin levels and color and to evaluate the effects of nutrient solutions with different salt concentrations on these parameters. The carotenoid content of control Atroviolaceum tomatoes was ca. 2-2.5-fold higher relative to the other two types, and the color of its puree could be visually distinguished from those of other genotypes. Salinity stress led in some cases to a 2-3-fold increase in the lycopene content. Saline treatment increased the accumulation of total anthocyanins in fruits of Sun Black (2-fold increase), while it reduced it in fruits of Anthocyanin (10-fold decrease). In general, the treatment increased the differences in color of different purees. These results indicate that salinity stress can lead to similar or higher increases in tomato carotenoids than those achieved by genetic engineering. In addition, these changes were accompanied by visually discernible color differences in tomato products. Our findings show the considerable potential of exploiting saline soils to obtain tomatoes with higher levels of secondary metabolites like carotenoids and anthocyanins.

Visual and instrumental evaluation of orange juice color: a consumers' preference study

Abstract: This study was aimed at (1) finding out correlations between the instrumental and the sensory evaluation of color attributes (lightness, chroma and hue) in orange juices (OJs) and (2) evaluating consumer preferences on OJs color. Fresh hand squeezed OJs from five varieties of oranges were evaluated by image analysis (DigiEye System, VeriVide Ltd., Leicester, UK) and spectroradiometer. Eighteen trained panelists classified the OJs in increasing order of hue (yellowish–reddish), chroma (dull–vivid) and lightness (clear–dark) and scored the colorimetric parameters on a continuous scale of 10 cm, anchored at the ends. Hue and lightness were well correlated with the instrumental measurement but not chroma. One hundred eleven consumers were asked to order the five OJs according to their color liking. A significant preference (P < 0.05) was observed for the OJs with intermediate hue and lightness values (Valencia Midnight). Consumers' segmentation was also explored by cluster analyses. PRACTICAL APPLICATIONS For the first time, the correlations between instrumental color parameters obtained with DigiEye and the sensory evaluation of color in orange juice (OJ) has been explored. These correlations have demonstrated that trained panelists can effectively evaluate orange juice hue and lightness. Small chroma differences (<2.96 CIELAB units) are not well appreciated by a trained panel and therefore would not be relevant for the industry. Consumers' preference for OJ color suggests that the preferred hues are the most orangish against other more reddish or yellowish ones. However, there are different segments of the population that show preference for more reddish hues.

Influence of Turbidity Grade on Color and Appearance of Virgin Olive Oil

Abstract: The appearance of most of the commercialized olive oils involves both their color and turbidity depending on the different technologies used for their elaboration. This research has been carried out to study the filtration impact on the colorimetric changes of virgin olive oils. Naturally turbid olive oils were blended at different proportions (100, 80, 60, 40, 20 and 0%) with their corresponding filtered replicates to obtain a scale of six levels of turbidity and simulating different turbidity grades. Tristimulus colorimetry, particularly the CIELAB uniform color, was used to follow color changes. As turbidity of the oil increased in the blend, yellowish oils, darker, and less saturated were obtained. Univariate correlations between the colorimetric parameters and turbid content were achieved with second degree polynomial equations, being chroma ( $$ C_{{_{\text{ab}} }}^{ *} $$ ) and hue (h ab) the best correlated parameters. The color differences ( $$ \Updelta E_{{_{\text{ab}} }}^{ *} $$ ) calculated between turbid oils (100%) and the consecutively decreasing turbid oils blends ranged from 3.18 to 18.72 CIELAB units, revealing differences in color visually perceptible to the human eye.

Effect of time and storage conditions on major volatile compounds of zalema white wine

Abstract: Changesinqualityattributesduringbottledstorageof whitewinewerestudied.Different storage conditions, temperature, bottle position and exposure to light were studied over 1 year and their effects on major volatile compounds were evaluated. Ethyl lactate and diethyl succinate contents increased after 12 months of storage, whereasisoamylacetatedecreasedoverthisperiod.Theanalysisof variancerevealed thatthetemperaturehadastatisticallysignificanteffectonmostvolatilecompounds studied. Multivariate statistical techniques (specifically principal component analysis and linear discriminant analysis) confirmed that temperature is the most important factor, so the samples were distributed into two groups according to storage temperature.Aroughdifferentiationamongwinesaccordingtothelengthofstoragewas also obtained using linear discriminant analysis.

Application of tristimulus colorimetry to evaluate colour changes during the ripening of Colombian guava (Psidium guajava L.) varieties with different carotenoid pattern

Abstract: Summary The pigment composition of three Colombian guava varieties, Regional roja, Regional blanca, and Palmira ICA-1, in unripe, turning and full ripe maturity stages was studied. Lycopene was identified as the major carotenoid of Regional roja and Palmira ICA-1 (18.25 and 28.07 mg kg−1 fruit, respectively in full ripe fruits) although a small amount of lutein was also found in the two varieties. β-Carotene was only found in Palmira ICA-1, whilst no detectable levels of carotenoids were found in the white-fleshed guava (Regional blanca). A good correlation between the total carotenoid content and the colour parameters of guava peel was found, such that the Regional roja and Regional blanca varieties could be discerned by colour coordinates. The most remarkable differences were found when comparing the pulp colour.

Effects of β‐cyclodextrin addition and farming type on vitamin C, antioxidant activity, carotenoids profile, and sensory analysis in pasteurised orange juices

Abstract: Summary The effects of organic farming, pasteurisation and addition of β-cyclodextrin on the content of vitamin C, colour, carotenoids and antioxidant capacity of orange juices were studied. After pasteurisation at 98 °C (20 s) and subsequently storage along 145 days at room temperature (20–25 °C), the loss of vitamin C content was around 30%. The effects of the thermal process on carotenoid were clearly observed in lutein (loss of 16% for organic and traditional 8%) and especially β-cryptoxanthin (loss of 30%). The colour changes were noticeable after the pasteurisation of orange juice and subsequent storage, with significant decreases being observed in lightness and the coordinate a*, while increases were found for coordinates b*, Hue* and chroma. The antioxidant capacity was 0.075 ± 0.01 and 0.053 ± 0.01 mMT mL−1 for organic and conventional, respectively, with losses around 40% being found at the end of the storage period. The addition of β-cyclodextrin caused no significant effects on the parameters under analysis. These data showed that strong thermal treatments, such as pasteurisation, adversely affect the nutritional and sensory quality of orange juices.

Application of multivariate statistical analyses to the study of factors affecting white wine volatile composition

Abstract: The influence of different storage conditions on the volatile composition of young white wine was evaluated during 1 year of storage. The wine was bottled and stored under different conditions of temperature, position and illumination. During storage, a significant increase in total content esters (mainly due to the increase in ethyl butyrate, ethyl acetate and diethyl succinate) and total content acids was detected. Also total content alcohols and carbonyl compounds decreased during storage. Storage time, temperature and illumination have a significant effect on esters content, whereas carbonyl compounds are affected by temperature, and alcohols content is affected by illumination. Stepwise linear discriminant analysis was applied to the experimental data. The results showed that the samples were well classified as a function of storage temperature. On the other hand, a certain trend was observed when the wine samples were classified according to storage time. The samples corresponding to two and four months of storage were well differentiated from the rest. PRACTICAL APPLICATIONS From a sensory point of view, the aroma influences greatly the quality of wines. The loss of aromatic characteristics in young white wine, as well as browning, take place over a variable period of time which ranges from one month to several years, depending on wine type and storage conditions. Assessment of possible factors affecting the useful lifespan of young white wine is of great interest for the wine making industry. Knowing the chemical composition of wine, specifically aromas, and its evolution relating to different storage and preservation conditions is an important tool in quality control.

Optical spectroscopy and pattern recogition techniques for discriminating and classifying Scotch whiskies

Abstract: The present study shows how optical spectroscopy can be innovatively used as a rapid and non-destructive tool to differentiate distinctive single malt Scotch whiskies with respect to commercial-grade blends, and for their classification according to the region of production. Absorption and fluorescence spectroscopy were combined with multivariate data analysis so as to build a discriminating map. The map showed that the clusters representing the single malt whiskies from selected distilleries were sharply separated from the cluster grouping the other whiskies of commercial-grade. Moreover, the cluster of single malt whisky was split into two subgroups, representing samples from two main macro-areas, the islands and the highlands, respectively.