49 research outputs found
Enhanced phycocyanin and protein content of <i>Arthrospira</i> by applying neutral density and red light shading filters: a small-scale pilot experiment
No full text© 2019 Society of Chemical Industry BACKGROUND: The cyanobacterium Arthrospira contains proteins and the blue pigment phycocyanin that can be used as a natural colourant in the food industry. The aim of this study was to investigate a strategy for increasing the yield of phycocyanin and protein from Arthrospira cultures by shading the cultures with neutral density and red light filters. Experiments were conducted under three different irradiance conditions: (i) laboratory tests under relatively low light intensities (100 μmol m −2 s −1 ), (ii) laboratory tests under relatively high light intensities (516 μmol m −2 s −1 ) and (iii) scaled-up tests under natural conditions by cultivating Arthrospira in raceway ponds in a greenhouse. RESULTS: In all cases, shading of cultures with red filters resulted in biomass with increased phycocyanin content achieving a maximum of 134, 71 and 121 mg g −1 under low light intensity, high light intensity and natural conditions, respectively. Under high light intensity and natural conditions, shaded cultures displayed phycocyanin of higher purity and increased protein content, which reached up to 43 and 65%, respectively. CONCLUSIONS: Shading of Arthrospira cultures by low-cost polyester red light filters may be an effective way for enhancing phycocyanin production and improving its purity in outdoor ‘spirulina farms’. © 2019 Society of Chemical Industry.sponsorship: The authors thank Research Foundation Flanders (FWO, grant nos. 1S16118N and 12D8917N) and EU Interreg V Vlaanderen-Nederland project 'De Blauwe Keten' for funding this research. (Research Foundation Flanders (FWO)|1S16118N, Research Foundation Flanders (FWO)|12D8917N, EU Interreg V Vlaanderen-Nederland project 'De Blauwe Keten')status: Publishe
Evaluatie van het potentieel van micro-algenbiomassa als bron van nieuwe anti-oxidanten met specifieke focus op polyfenolen
No full textSince the beginning of the new millennium, research efforts as well as commercial activities concerning mass cultivation and applications of microalgae have gained momentum. The main current and future applications of microalgae are situated in four fields, i.e. biofuel production, wastewater treatment, aquaculture and high-value products. Antioxidants are a commercially important class of high-value products that could be obtained from microalgae. Antioxidants are omnipresent with applications in food and feed industry, cosmetics as well as in the chemical industry. The main objective of this PhD study was therefore to evaluate the potential of microalgae as a source of antioxidants, in view of future applications in food products, and to learn more about the different metabolites that contribute to the antioxidant activity of these unicellular photosynthetic organisms.From our results, it can be concluded that microalgae contain relatively high amounts of antioxidants and are therefore an appealing alternative to higher plants for the production of natural antioxidant preparations. Although microalgae are well known for their high carotenoid content, other components are important as well in relation to the antioxidant activity. In some microalgal extracts, the presence of pigments can interfere with evaluation of antioxidant activity by traditional assays that are based on spectrophotometric measurements. Therefore, the use of voltammetry as an alternative methodology for measuring antioxidant activity was investigated. Antioxidant measurement by square wave voltammetry correlated well with other established antioxidant assays and proved to be a reliable method to assess antioxidant activity in complex matrices. It was further found that antioxidant activity of microalgae highly depends on nutrient availability and growth stage. It was obvious that cultivating under nutrient limitation, especially when nitrogen is limited, leads to biomass that is poor in antioxidant activity. Although phenolic content and carotenoid content were significantly lower in biomass from nutrient deficient cultures, production of the antioxidant vitamins C and E was enhanced under nutrient limited conditions, particularly when phosphorus was the limiting nutrient. The fact that vitamins C and E contents increased upon nutrient stress while total antioxidant activity decreased suggests that the contribution of these vitamins to total antioxidant activity of the biomass is relatively little.Interestingly, microalgae do contain significant amounts of phenolics, comparable to those of carotenoids. A minor part (ppb levels) of the phenolics appear to be flavonoids, a class of polyphenols that until recently was believed to be totally absent in microalgae. In this PhD, the presence of recognized key intermediates of flavonoid biosynthesis (chalcones, dihydrochalcones, and dihydroflavonols) was demonstrated for the first time in microalgae, which points to the existence in microalgae of a plant-like flavonoid biosynthetic pathway and raises the fundamental question on the ancestral physiological function of flavonoids.status: Publishe
Humulus Lupulus: Hop Alpha-acids Isomerization. A Review.
No full textThis paper gives an extensive overview of the research performed in relation to hop a-acids isomerization. The objective is to present a summary on developments and findings which can serve as a background for future work regarding more efficient use of humulones and isohumulones. To this end, first, an overview of the research which has been performed in relation to the a-acids isomerization mechanism and kinetics is provided. Following, the influence of common parameters, such as temperature, pH, the concentration of humulones, metal ion catalysts, etc., on a-acids isomerization is presented. In this review, structures and mechanisms that are presented correspond to original data found in literature and were, consequently, not adapted to the newly proposed structure of a-acids and iso-a-acids (According to Urban et al. [1]).status: Publishe
Microalgae as a Novel Source of Antioxidants for Nutritional Applications
No full text© 2015 Elsevier Inc. All rights reserved. Lipid oxidation is an important factor in determining shelf life of foods, and it can be counteracted by the addition of antioxidants. Traditionally used synthetic antioxidants are increasingly being replaced by natural alternatives. Microalgae could be a novel source of food-grade antioxidants because they are rich in carotenoids, vitamins, and phenolics. This chapter provides an overview of the process of lipid oxidation and commonly used antioxidants. Furthermore, the biological background of antioxidant formation in microalgae as a response to oxidative stress is described. Important enzymatic and nonenzymatic antioxidant defense mechanisms of microalgae are defined, and factors influencing their formation are discussed. Finally, an overview of the current knowledge and future prospects on the use of microalgal antioxidants to retard lipid oxidation in foodstuff is given.status: Publishe
Microalgae as a source of (phenolic) antioxidants for food, feed and industrial applications
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Influence of high pressure homogenization on free fatty acid formation in Nannochloropsis sp
No full textAlthough Nannochloropsis lipids have many potential applications in biofuels and high value products, their extraction is limited by the tough cell wall of this species. High pressure homogenization (HPH) can be used to improve the extraction efficiency. However, this can possibly induce free fatty acid (FFA) formation, which has a negative impact on oil quality. In this study, the HPH pressure and number of passes were varied in a full factorial design to study the impact of these factors on FFA formation, lipid extraction efficiency and fatty acid profile.
It was found that substantial amounts of FFA were formed during HPH treatments when compared to the non-disrupted biomass. The FFA formation was mostly influenced by the number of passes applied, which can explained by a combined effect of the longer time residing as a wet paste and the temperature increase during the treatment. The large amount of FFA formed during the least intensive HPH treatment is in contrast with only a slight increase of the lipid extraction efficiency, which indicates that minor damage to the cell is sufficient to induce lipolytic reactions. The relative fatty acid profile after HI extraction was not influenced by the HPH treatment.sponsorship: The research presented in this paper was financially supported by Flanders Innovation Hub for Sustainable Chemistry (FISCH) in the FISCH-ICON (IWT) project OMEGA-EXTRACT and by Flanders Innovation & Entrepreneurship (VLAIO strategic research grant L. Balduyck). The authors thank Proviron Industries nv (Hemiksem, Belgium) for the cultivation and harvesting of the microalgae and the Laboratory of Food Technology (Department of Microbial and Molecular Systems, KU Leuven, Kasteelpark Arenberg 22, Leuven, Belgium) for the use of the high pressure homogenizer. The authors sincerely thank Dr. Sam Eyley (KU Leuven Kulak, Kortrijk, Belgium) for revising the language of the manuscript. (Flanders Innovation Hub for Sustainable Chemistry (FISCH), Flanders Innovation & Entrepreneurship (VLAIO strategic research grant))status: Publishe
Supercritical CO2 extraction of lipids and other valuable products from microalgae
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Supercritical CO2 extraction of lipids and other valuable products from microalgae
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Supercritical CO2 extraction of lipids and other valuable products from microalgae
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