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- Potencial biotecnológico das microalgasPublication . Carvalho, A. P.; Meireles, L. A.; Malcata, F. X.; Oliveira, G.; Raposo, M. F.; Morais, R.
- Effect of salt concentration and light intensity on carotenogenesis of Haematococcus pluvialisPublication . Rijo, Paula; Tsavalos, A.; Morais, R.; Young, A.
- Spray-drying of Dunaliella salina to produce a β -carotene rich powderPublication . Leach, G.; Oliveira, G.; Morais, R.Powders of Dunaliella salina biomass were obtained by spray drying a cell concentrate under different drying regimes. A three-factor, two-level experimental design was employed to investigate the influence of inlet temperature, outlet temperature and feed solids on b-carotene recovery. The effect of microencapsulation in a polymer matrix of maltodextrin and gum arabic was also studied. All powders were stored under specific conditions to assess the stability of the native b-carotene. There was a trend indicating that lower outlet temperature yielded higher carotenoid recoveries, b-carotene recovery varying between 57% and 91%. Microencapsulated biomass yielded 100% recoveries. All non-microencapsulated powders were unstable in terms of b-carotene content in the presence of natural light and oxygen showing 90% degradation over a 7-day period. The incorporation of a microencapsulating agent had a significant increase in the storage stability. Results indicated a first-order degradation of the b-carotene in microencapsulated powders with kinetic constants of 0.06 day-1 and 0.10 day-1. HPLC analysis showed no effect of drying processes on isomer composition (9-cis-b-carotene and all-trans-b-carotene ratio). This behaviour was also observed during storage of the microencapsulated powders.
- Evaluation of different cell disruption processes efficiency on encysted cells of Haematococcus pluvialis: effects on astaxanthin recovery and implications for bio-availabilityPublication . Mendes-Pinto, M. M.; Raposo, M. F. de J.; Bowen, J.; Young, A. J.; Morais, R.
- Evaluation of different cell disruption processes on encysted cells of Haematococcus pluvialis: effects on astaxanthin recovery and implications for bio-availabilityPublication . Mendes-Pinto, M.M.; Raposo, M.F.J.; Bowen, J.; Young, A.J.; Morais, R.Although Haematococcus pluvialis is one of the most importantnatural sources of the carotenoid astaxanthin as a pigmentor for theaquaculture industry, the thick sporopollenin cell wall in the cysts hindersastaxanthin extraction and its subsequent bio-availability to fish. A rangeof physical and chemical processes were tested to promote the disruptionof the encysted cells. The efficacy of these processes was evaluated interms of astaxanthin recovery, which was assessed by determining theextent of leaching of astaxanthin into an organic solvent. The processestested were: autoclave 30 min, 121 °C, 1 atm; HCl 0.1 M, 15min and 30 min; NaOH 0.1 M, 15 min and 30 min; enzymatictreatment with a mixture of 0.1% protease K and 0.5% driselase in aphosphate buffer, pH 5.8, 30 °C, for one hour; spray drying, inlet180 °C, outlet 115 °C; and mechanical disruption, with acell homogeniser developed for this purpose. The mechanical(homogenisation) and autoclave treatments were the most effective in termsof extraction and availability.
- Functional vegetable-based sausages for children consumptionPublication . Burri, S.; Tato, I; Nunes, M.L.; Morais, R.
- On the utilization of the algal biomass grown in a brewery effluent in animal feedPublication . Raposo, M. Filomena de J.; Oliveira, Susana; Castro, Paula M. L.; Bandarra, Narcisa; Morais, R.
- Effect of carotenoid source and dietary lipid content on blood astaxanthin concentration in rainbow trout (Oncorhynchus mykiss)Publication . Barbosa, M. J.; Morais, R.; Choubert, G.Astaxanthin concentration in the blood of rainbow trout was studied in a feeding trial with two different astaxanthin sources: green algae Haematococcus pluvialis and commercial beadlets of 8% astaxanthin content (CAROPHYLL® Pink), and two different dietary lipid levels. The green algae contained 1.4% of carotenoids on a dry matter basis: free astaxanthin (<1%), astaxanthin monoester (24.3%); astaxanthin diester (70.2%) and lutein (4.8%). Algal biomass was mechanically ground to disrupt the cell wall before incorporation in the feed. Hydrolysis of astaxanthin esters from algae occurred during the pelletization even at a low process temperature (43°C). Rainbow trout with an initial mean body weight of 150 g were fed experimental diets supplemented at a rate of 100 mg pigment/kg diet combined with two different lipid levels (9 and 24%) during 5 days. Astaxanthin concentration in the serum ranged from 5.3 μg/ml (8.9 nmol/ml) to 9.0 μg/ml (15.1 nmol/ml). Astaxanthin concentration in the serum was higher for fish fed high lipid level diets, independently of the astaxanthin source. No differences in the astaxanthin serum concentration were found for fish fed diets supplemented with either natural or synthetic astaxanthin, respectively 9.0±1.9 and 8.4±2.4 μg astaxanthin/ml serum, when dietary lipid level was high (24%). On the other hand, there was a higher blood astaxanthin concentration in fish fed diets supplemented with algal biomass (7.0±2.4 μg astaxanthin/ml serum) compared to synthetic astaxanthin (5.3±2.0 μg astaxanthin/ml serum) when dietary lipid level was low (9%)
- The growth of microalgae using an effluent from a brewery as the culture nutrient mediumPublication . Raposo, M Filomena de J; Oliveira, Susana; Castro, Paula M. L.; Bandarra, Narcisa; Morais, R.
- Three triterpenoids and one flavonoid from the liverwort Asterella blumeana grown in vitroPublication . Neves, M.; Morais, R.; Gafner, S.; Hostettmann, K.This is the first report on the chemical constituents of Asterella blumeana. Three triterpenoids (22-hydroxyhopane, 22,29-dihydroxyhopane, 6a,22-dihydroxyhopane) and one flavonoid (isoscutellarein- 7,8,4'-trimethyl ether) were isolated from the CH2Cl2 extract of the liverwort Asterella blumeana grown in vitro. The structures of isolated compounds were established by spectroscopic methods (UV, EI mass spectroscopy, 1H- and 13C-NMR). 22,29-dihydroxyhopane is a new natural compound.