Juan Garrido-Fernández

Color-pigment correlation in virgin olive oil

The chlorophyll and carotenoid content of virgin olive oils from five varieties harvested at varying degrees of ripeness were determined. Colors were evaluated from the chromatic ordinates L*, a*, b* of the absorption spectrum. Oil color changes for different varieties or stages of ripeness are directly related to pigment content and a* and b* values. The statistical study made on both series of parameters proves that there is a good correlation between them. The carotenoid content and b* have one of the best correlation coefficients (r) and is easily measured. This methodology evaluates chlorophyll and carotenoid content, an additional attribute for evaluation of virgin olive oil quality.

Pigments present in virgin olive oil

The qualitative and quantitative control of pigments in ripe olives and in extracted virgin olive oil has increased our knowledge of the influence on these compounds in the areas of ripening of the fruit, storage time in the factory and the oil extraction process. As the harvesting time of the fruits increases, pigment content decreases. During storage, the presence of lipoxygenase has been detected, as well as a considerable decrease in chlorophylls and a small decrease in carotenoids. During the extraction process, the chlorophyllic fraction is destroyed in the greater part, and although the carotenoid fraction is also affected, its concentration increases in the oil with respect to that in the fresh fruit. In the pigment degradation, in addition to the acid-catalyzed reaction, the presence of lipoxygenase suggests a role for this enzyme.

Action of chlorophylls on the stability of virgin olive oil

Virgin olive oil was used as substrate to study the influence of chlorophylls on its oxidative stability in light and in darkness. Chlorophylls a and b were added to this substrate, after which oils were stored at 36 ± 2°C for three months under artificial light (1340 lux) or in darkness. The effect of light was greater than that of the additives. The prooxidant action of chlorophylls in the presence of other pigments of the oil was not observed in this assay. During early storage, the rate of peroxide formation was lower in the samples with added chlorophylls, but later it equalled that of the control. In darkness, stability was greater in the samples containing chlorophylls, indicating a slight antioxidant effect, which was more marked for chlorophyll a.

Dertermination of chlorophylls and carotenoids by high-performance liquid chromatography during olive lactic fermentation

Abstract Eighteen pigments, including chlorophylls, carotenoids and their degradation products, were separated by reversed-phase ion-pair high-performance liquid chromatography during the lactic fermentation and later preservation phase of green table olives. The method consists of an elution gradient using two solvents: water-ion-pair reagent-methanol (1:1:8, v/v/v) and methanol-acetone (1:1, v/v). Absorbance detection of all the pigments is carried out spectrophotometrically at 430 nm. Pigment concentrations are calculated from an extension of Beers law. This procedure is compared with the external standard method. The analysis of variance showed no significant differences between the results given by the two methods.

Diet explains interpopulation variation of plasma carotenoids and skin pigmentation in nestling white storks.

Carotenoids have a dietary origin in birds, but mechanisms by which they are absorbed in the gut, transported in the blood, metabolized at various sites, and deposited in the integument remain poorly understood. Variation in both plasma carotenoid levels and external color may reflect different access to dietary carotenoids or individual physiological differences in the uptake and deposition of carotenoids. We compared total plasma carotenoid concentration in nestling white storks (Ciconia ciconia) from 11 Spanish colonies in two consecutive years. The main food item in one of the colonies was the red swamp crayfish (Procambarus clarkii), a recently introduced species. Storks in the remaining colonies ate a variety of foods but no crayfish. Total plasma carotenoid levels in the colony where crayfish were consumed were about five times higher than in any other colony. These differences were maintained after controlling for the significant interyear variability, as well as for sex, age, and body mass of birds. Skin pigmentation also differed, being intensely orange in storks that consumed crayfish but white (unpigmented) in the remaining individuals. With thin‐layer chromatography (TLC) and electronic absorption spectroscopy, astaxanthin was confirmed as the major carotenoid in crayfish as well as in the plasma, skin, and body fat of crayfish‐eating storks, whereas lutein was the main carotenoid in plasma samples from the other colonies. These results indicate that a newly available carotenoid in the environment, astaxanthin, can be absorbed in large quantities from the gut and be transported in the blood before deposition in different tissues.

Lipoxygenase activity during pepper ripening and processing of paprika

Abstract The crude enzymatic extract obtained directly by trituration of the fruits of Capsicum annuum in phosphate buffer followed by filtration was shown to be suitable for the measurement of lipoxygenase activity. The use of Triton X-100 did not improve extraction and the use of DTT to protect the enzyme against oxidizers was not necessary. The optimum pH was 7 for the extraction and 6.5 for measurement of activity. The number of previous harvests from the plant had a marked effect on the levels of lipoxygenase activity during ripening of the fruits from two varieties of pepper. During drying, there was a progressive loss of activity in both varieties.

Environmental-induced acquisition of nuptial plumage expression: a role of denaturation of feather carotenoproteins?

Several avian species show a bright carotenoid-based coloration during spring and following a period of duller coloration during the previous winter, despite carotenoids presumably being fully deposited in feathers during the autumn moult. Carotenoid-based breast feathers of male linnets (Carduelis cannabina) increased in hue (redness), saturation and brightness after exposing them to outdoor conditions from winter to spring. This represents the first experimental evidence showing that carotenoid-based plumage coloration may increase towards a colourful expression due to biotic or abiotic environmental factors acting directly on full-grown feathers when carotenoids may be fully functional. Sunlight ultraviolet (UV) irradiation was hypothesized to denature keratin and other proteins that might protect pigments from degradation by this and other environmental factors, suggesting that sunlight UV irradiation is a major factor in the colour increase from winter to spring. Feather proteins and other binding molecules, if existing in the follicles, may be linked to carotenoids since their deposition into feathers to protect colourful features of associated carotenoids during the non-breeding season when its main signalling function may be relaxed. Progress towards uncovering the significance of concealment and subsequent display of colour expression should consider the potential binding and protecting nature of feather proteins associated with carotenoids.

Greater flamingos Phoenicopterus roseus use uropygial secretions as make-up

It was long thought that the colour of bird feathers does not change after plumage moult. However, there is increasing evidence that the colour of feathers may change due to abrasion, photochemical change and staining, either accidental or deliberate. The coloration of plumage due to deliberate staining, i.e. with cosmetic purposes, may help individuals to communicate their quality to conspecifics. The presence of carotenoids in preen oils has been previously only suggested, and here we confirm for the first time its presence in such oils. Moreover, the carotenoids in the uropygial secretions were the same specific pigments found in feathers. We show not only that the colour of feathers of greater flamingos Phoenicopterus roseus became more colourful due to the application of carotenoids from uropygial secretions over the plumage but also that the feathers became more colourful with the quantity of pigments applied over them, thus providing evidence of cosmetic coloration. Flamingos used uropygial secretions as cosmetic much more frequently during periods when they were displaying in groups than during the rest of the year, suggesting that the primary function of cosmetic coloration is mate choice. Individuals with more colourful plumage initiated nesting earlier. There was a correlation between plumage coloration before and after removal of uropygial secretions from feathers’ surfaces, suggesting that the use of these pigmented secretions may function as a signal amplifier by increasing the perceptibility of plumage colour, and hence of individual quality. As the cosmetic coloration strengthens signal intensity by reinforcing base-plumage colour, its use may help to the understanding of selection for signal efficacy by making interindividual differences more apparent.

Preparation of Cu(II) complexes of oxidized chlorophylls and their determination by thin-layer and high-performance liquid chromatography

Abstract Different allomerization products of pheophytins a and b have been obtained by alkaline treatment in the presence of atmospheric oxygen and isolated by normal phase thin-layer chromatography (NP-TLC) and semi-preparative high-performance liquid chromatography (HPLC). 3 1 ,3 2 -Didehydro-151-hydroxy-15 1 -hydroxy-rhodochlorin-15-acetic acid δ-lactone-15 2 -methyl-17 3 -phytyl ester ( a and b ) and 3 1 ,3 2 -Didehydro-rhodochlorin-15-glyoxylic acid-17 3 -phytyl ester ( a and b ) have been identified as principal products. Identification was based on UV-Vis and mass spectra, retention times and R F values. The molecular mass of allomerized pheophytins was confirmed by positive-ion fast-atom bombardment mass spectrometry and positive/negative ion electrospray mass spectrometry. The corresponding Cu(II) complexes of these compounds were prepared by chelation reaction with CuCl 2 and separated by reversed-phase ion-pair high-performance liquid chromatography (RP-IP-HPLC) using a gradient of water and ion suppressor-methanol-acetone. The Chromatographic characteristics in NP-TLC and RP-IP-HPLC of the Cu(II) complexes are reported. The corresponding UV-Vis spectra obtained with an on-line diode-array detector have been included.

The liver but not the skin is the site for conversion of a red carotenoid in a passerine bird

Carotenoids may provide numerous health benefits and are also responsible for the integumentary coloration of many bird species. Despite their importance, many aspects of their metabolism are still poorly known, and even basic issues such as the anatomical sites of conversion remain controversial. Recent studies suggest that the transformation of carotenoid pigments takes place directly in the follicles during feather growth, even though the liver has been previously recognised as a storing organ for these pigments with a certain potential for conversion. In this context, we analysed the carotenoid profile of plasma, liver, skin and feathers of male Common Crossbills (Loxia curvirostra). Interestingly, the derivative feather pigment 3-hydroxy-echinenone was detected in the liver and in the bloodstream (i.e. the necessary vehicle to transport metabolites to colourful peripheral tissues). Our results demonstrate for the first time with empirical data that the liver may act as the main site for the synthesis of integumentary carotenoids. This finding contradicts previous assumptions and raises the question of possible inter-specific differences in the site of carotenoid conversion in birds.