José Empis

Evolution of pigment composition in Chlorella vulgaris

The onset of carotenogenesis in Chlorella vulgaris and the change in nature and concentration of pigments with time was studied. The succession of pigments observed was interpreted in terms of relative efficiencies of carotenoid interconversion pathways, and this might be used to monitor the progress of the carotenogenic process. This work is relevant to the use of dry Chlorella biomass, as a naturally encapsulated form of a natural colouring ingredient, in animal feed.

Relative stabilities of microalgal carotenoids in microalgal extracts, biomass and fish feed: effect of storage conditions

Carotenoids, whose functional importance has become the object of much attention in the last years, are a source of vitamin A and food colouring agents for both animals and/or humans. As consumer demand for natural carotenoids increases, there is a natural barrier to their utilisation insofar as their low stability to oxidative environments is concerned. The aim of this work was to test stability of carotenoids present in microalgal biomass, such as Chlorella vulgaris (Cv) and Haematococcus pluvialis (Hp), already proven to be efficient colouring agents and of their acetone extracts, both as such and in formulated feeds, under different storage conditions, namely at room temperature under light exposure, at room temperature in the dark, frozen at −18 °C, with added antioxidant (0.01% ascorbic acid at room temperature) and stored under vacuum or nitrogen atmosphere. The best storage conditions for microalgal dry biomass carotenoids were under vacuum in both microalgae, when retention totaled 80 and 90%, respectively, for Cv and Hp, even after 1.5 years. Carotenoid extract stabilities were found to be much shorter, and loss of carotenoid pigments was almost total after 15 and 30 days, respectively, for Cv and Hp. In formulated diets, carotenogenic biomass revealed stability during the maximum storage period of six months. As a conclusion, both microalgal dry biomasses may constitute natural, encapsulated and relatively concentrated forms of edible carotenoids, which exhibit good preservation without any special storage conditions, both as such or in finished fish feed.

Chlorella vulgarisused to Colour Egg Yolk

Dry biomass obtained from stressed cells of Chlorella vulgaris (rich in carotenoid pigments) was used as such in animal feed, instead of the commercial synthetic pigment. The in vivo effect of microalgal biomass as substitute pigment was ascertained with Hisex brown hens kept laying during 37 days under conventional conditions, and strongly suggested that yolk pigmentation was comparable to that obtained using commercial pigments, when comparable weight of colourant was formulated into the feed.

Potential use of a microalga (Chlorella vulgaris) in the pigmentation of rainbow trout (Oncorhynchus mykiss) muscle

The main purpose of this work was to evaluate the colouring effect of carotenoids present in dry biomass obtained from stressed cells ofChlorella vulgaris. Total carotenoids represented only 0.2% of dry algal biomass and consisted mainly of canthaxanthin, lutein, astaxanthin and their esters. — A rainbow trout feeding trial was conducted in order to investigate the effects of dietary algal incorporation as a pigment source, in comparison to that obtained with synthetic pigments, both astaxanthin and canthaxanthin. — The colour intensities measured in muscle were compared, in each case, with those which constitute the Salmonids Roche Colour Card, and proved similar after both 3 and 6 weeks feeding, with a significant increase detected, but at the end of experiment (9 weeks) the increase was shown only in spectrophotometric (quantitative) results.Chlorella vulgaris biomass, which is storable without any special precautions, thus appears to be a promising source of carotenoids to use in commercial fish finishing diets, quite comparable in efficiency with the existing synthetic pigments. Algal biomass micronization, which was also tried out, was not found to be advantageous for the efficiency of colouring, no evidence having been found of any difference in its absorption and in the distribution of pigment through muscle, even if a 150-g rainbow trout, which has a rather short digestive tract, was used.

Use of Chlorella vulgaris as a carotenoid source for rainbow trout: effect of dietary lipid content on pigmentation, digestibility and retention in the muscle tissue

Apparent digestibility, deposition and retention of carotenoids in the muscle of rainbow trout, Oncorhynchus mykiss, were investigated comparing the feeding of pigments from Chlorella vulgaris against commercially available pigments at two different total lipid contents (15% and 20% lipid). Algal biomass (ALG) was included in rainbow trout diets and muscle pigmentation was compared to that obtained in trout fed diets containing a 5:3 mixture of canthaxanthin and astaxanthin (MIX) (reflecting the relative concentrations of these carotenoids in the dry alga) or those fed a diet containing astaxanthin only (AST). Apparent digestibilities of pigments and nutrients were determined by the indirect method, using Cr2 O3 as indicator, and the colour intensity and pigment concentration were assessed in the muscle, using the Roche colour card for salmonids and UV-vis spectrophotometry. After 6 weeks feeding, colour intensity was similar for the various pigment sources, achieving levels 12 to 13, yet significantly higher in fish fed the diet with the higher lipid content (≈ 20%) (p<0.05). Pigment concentration in the muscle was also higher in the fish fed the high-fat diet. Muscle pigment concentrations were similar for fish fed diets ALG and MIX, and over 1.5 times higher than for diet AST (p<0.05) after 6 weeks. Apparent digestibility of dry matter, crude protein, lipid, total energy and specific carotenoid concentrations were also measured. Increased dietary fat content was shown to increase the deposition and the retention of carotenoids in muscle, and the difference increased with time (deposition increase of 10–20% at week 3 and 30–40% at week 6 and retention increase of 10–15% at week 3 and 30% at week 6). Pigment digestibility also apparently increases (10–20%) under those conditions despite the fact that no significant effects in terms of apparent digestibility increase were found for dry matter, protein, lipids or energy.

Method to Evaluate Foaming Performance

in this work, a methodology to evaluate foaming capacity and stability is proposed. With this method the foam volume decay is followed and the overrun [(foam volume -solution volume)isolution volume] plotted against time. The integral of overrun decay for a jixed period was tried out as a single parameter to describe foam properties, i.e. foaming capacity and foam stability. It was concluded that using this single parameter; the foaming stability index (ES.I.),, the application of statistical experimental design methodology to optimise foaming becomes straightforward. As an example of an application of this method, the denaturation extent of the protein was optimised to improve the foaming properties of Lupin protein isolate. 0 1998 Elsevier Science Limited. A 11 rights reserved

β-Cyclodextrin Complexes of Benzaldehyde, Vanillin and Cinnamaldehyde: A Raman Spectroscopic Study1

Abstract Raman spectra of benzaldehyde, vanillin and trans-cinnamaldehyde, and of their complexes in β-cyclodextrin are presented and discussed. The guest molecules provide both an aromatic ring for privileged interaction with the cyclodextrin cavity, and characteristic vibrations (e.g., vC=O, vC=C, vCCϕ (ϕ=phenyl), vC-Hϕ) with group frequencies in spectral regions free from cyclodextrin bands which are useful for probing the guest perturbed by complex formation with β-cyclodextrin. In particular, the C=O bond is shown to be a good vibrational spectroscopic probe to monitor the effects of both the medium, through its dielectric constant, and of specific interactions, namely of the hydrogen bonding type. The first of these effects is evaluated theoretically and a Kirkwood-Bauer-Magat plot for benzaldehyde is used to estimate the effective dielectric constant for the guest in the benzaldehyde-β-cyclodextrin complex. The above mentioned Raman spectroscopic results are interpreted and discussed.

Isolation of bacterial strains capable of using lupanine, the predominant quinolizidine alkaloid in white lupin, as sole carbon and energy source

Seven Gram-negative bacterial strains, capable of using lupanine, the predominant quinolizidine alkaloid in white lupin, as sole carbon and energy source, were isolated from soil in whichLupinus albus andL. luteus had been grown. A metabolic profile system (BIOLOG) identified only three of the seven isolates, two asXanthomonas oryzae pvoryzae E and one asGluconobacter cerinus. The maximum specific growth rates of the seven isolates when incubated at 27°C in a medium containing as sole carbon source 2 g L−1 of lupanine, ranged from 0.05 to 0.13 h−1 and the concentration of dry biomass at the stationary phase ranged from 0.7 to 1.1 g L−1. Unidentified strains IST20B and IST40D exhibited the highest maximum specific growth rates (0.13h−1), removed 99% of the initial lupanine after 30 h of incubation, and the dry biomass yields did not exceed 0.4 g per g lupanine consumed. Strain IST20B is of potential use forL. albus debittering because, after 32 h growth in aqueous extracts ofL. albus, 85% of initial alkaloids were removed while the concentration of soluble protein was only reduced by 8%.

Inclusion of carvone enantiomers in cyclomaltoheptaose (β-cyclodextrin): thermal behaviour and H→D and D→H exchange

The inclusion compounds of carvone enantiomers in cylcomaltoheptaose (beta-cyclodextrin, betaCD) are studied at defined temperatures above room temperature and in relation to H-->D and D-->H exchanges. Loss of water molecules and release of carvone molecules from the betaCD cavity are caused by increase of temperature above room temperature and are measured by the integrated intensities of the O-H and C-H Raman stretching bands, respectively. In turn, H-->D and D-->H exchanges are monitored by the integrated intensities of the O-H and O-D Raman stretching bands, respectively. All of these processes were followed in real time with a Raman spectrometer equipped with CCD detection. The results indicate that distinct carvone enantiomers lead to the formation of different betaCD inclusion hydrates that have different water content and hydration structures. In particular, the results suggest that SCarv-betaCD has a greater water content, dehydrates strongly for temperatures above room temperature, and exchanges protons faster than the RCarv-betaCD complex.

Dynamics of hydration and dehydration processes of β-cyclodextrin monitored in real time by Raman spectroscopy

The integrated intensity of the O–H Raman stretching band of crystalline β-cyclodextrin hydrate exhibits a linear response to variations of ambient humidity for humidities > 15% and varies with temperature in a similar way as the sample thermogram; it is used to monitor, in real time, the hydration and dehydration processes which follow approximately first-order kinetics.