Algal products beyond lipids: Comprehensive characterization of different products in direct saponification of green alga Chlorella sp

Carotenoids Biosynthesis, Accumulation, and Applications of a Model Microalga Euglenagracilis

The carotenoids, including lycopene, lutein, astaxanthin, and zeaxanthin belong to the isoprenoids, whose basic structure is made up of eight isoprene units, resulting in a C40 backbone, though some of them are only trace components in Euglena. They are essential to all photosynthetic organisms due to their superior photoprotective and antioxidant properties. Their dietary functions decrease the risk of breast, cervical, vaginal, and colorectal cancers and cardiovascular and eye diseases. Antioxidant functions of carotenoids are based on mechanisms such as quenching free radicals, mitigating damage from reactive oxidant species, and hindering lipid peroxidation. With the development of carotenoid studies, their distribution, functions, and composition have been identified in microalgae and higher plants. Although bleached or achlorophyllous mutants of Euglena were among the earliest carotenoid-related microalgae under investigation, current knowledge on the composition and biosynthesis of these compounds in Euglena is still elusive. This review aims to overview what is known about carotenoid metabolism in Euglena, focusing on the carotenoid distribution and structure, biosynthesis pathway, and accumulation in Euglena strains and mutants under environmental stresses and different culture conditions. Moreover, we also summarize the potential applications in therapy preventing carcinogenesis, cosmetic industries, food industries, and animal feed.

Production of microalgae with high lipid content and their potential as sources of nutraceuticals

In the current global scenario, the world is under a serious dilemma due to the increasing human population, industrialization, and urbanization. The ever-increasing need for fuels and increasing nutritional problems have made a serious concern on the demand for nutrients and renewable and eco-friendly fuel sources. Currently, the use of fossil fuels is creating ecological and economic problems. Microalgae have been considered as a promising candidate for high-value metabolites and alternative renewable energy sources. Microalgae offer several advantages such as rapid growth rate, efficient land utilization, carbon dioxide sequestration, ability to cultivate in wastewater, and most importantly, they do not participate in the food crop versus energy crop dilemma or debate. An efficient microalgal biorefinery system for the production of lipids and subsequent byproduct for nutraceutical applications could well satisfy the need. But, the current microalgal cultivation systems for the production of lipids and nutraceuticals do not offer techno-economic feasibility together with energy and environmental sustainability. This review article has its main focus on the production of lipids and nutraceuticals from microalgae, covering the current strategies used for lipid production and the major high-value metabolites from microalgae and their nutraceutical importance. This review also provides insights on the future strategies for enhanced microalgal lipid production and subsequent utilization of microalgal biomass.

GRAPHICAL ABSTRACT

High Protein Substitutes for Gluten in Gluten-Free Bread

Gluten-free products have come into the market in order to alleviate health problems such as celiac disease. In this review, recent advances in gluten-free bread are described along with plant-based gluten-free proteins. A comparison with animal-based gluten-free proteins is made reporting on different high protein sources of animal origin. Sea microorganisms- and insect-based proteins are also mentioned, and the optimization of the structure of gluten-free bread with added high protein sources is highlighted along with protein digestibility issues. The latter is an issue for consideration that can be manipulated by a careful design of the mixture in terms of phenolic compounds, soluble carbohydrates and fibres, but also the baking process itself. Additionally, the presence of enzymes and different hydrocolloids are key factors controlling quality features of the final product.

Food and Beverages Containing Algae and Derived Ingredients Launched in the Market from 2015 to 2019: A Front-of-Pack Labeling Perspective with a Special Focus on Spain

Algae are a source of functional ingredients, with a large spectrum of healthy and functional compounds. Therefore, this study aimed to provide an overview on commercialized food and beverages made from algae and derived ingredients, with emphasis on the Spanish market, relying on the front-of-pack labeling. For this reason, the Mintel Global New Products Database was searched for foods and beverages containing “algae” ingredients, launched during the period 2015–2019. A total of 13,090 items were found worldwide, including 5720 items in Europe, in which 436 items were in Spain. Regardless of the market (global, European, and Spanish), a similar number of products categories (n = 20), dominant categories (dairy and desserts and ice cream) and dominant algal ingredient (carrageenans) were found. Nutritional information retrieved from Spanish products underlined that algae-based snacks had significantly lower energy, fat, and salt content compared to algae-free counterparts. On the contrary, spirulina- enriched ready to drink beverages had significantly higher energy and salt than algae-free. As such, reading the nutritional labeling is crucial to selecting products that suit consumer needs or/and expectations. Furthermore, only 8% of products reported the algal species and the level of inclusion, so this study emphasizes the importance of labeling legislation to provide complete product information to consumers.

Biorefinery of Dunaliella salina: Sustainable recovery of carotenoids, polar lipids and glycerol

Dunaliella salina is well-known for its high content in carotenoids and glycerol. Nevertheless, Dunaliella salina has also a high content in lipids, including polar lipids, which are suitable for nutraceutical/cosmeceutical applications. This work proposes a sustainable process to maximise the potential of Dunaliella salina for the production of distinct fractions of carotenoids, glycerol, polar lipids and proteins, which may contribute to improve the revenues of the microalgae industry. In this work, extraction with non-hazardous solvents and organic solvent nanofiltration are integrated, in order to obtain added-value products and glycerol. Also, aiming to separate carotenoids from glycerides, a saponification process is proposed. High overall recoveries were obtained for carotenoids (85%), glycerol (86%), polar lipids (94%) and proteins (95%). In order to evaluate the profitability of the proposed biorefinery, an economic assessment was accomplished. Both CAPEX and OPEX (Capital and Operating expenditure) were calculated, likewise the Return of Investment (ROI).

Microbial fuel cell powered by lipid extracted algae: A promising system for algal lipids and power generation

In this study, a promising microbial fuel cell (MFC) system has been developed, wherein algae is cultivated in the cathode chamber, algae biomass is harvested and lipids are extracted. The lipid extracted algal (LEA) biomass was then used asan electron donor substrate. The performance of MFCs fed with LEA biomass was compared with that of fruit waste fed MFCs (FP-MFCs), wherein LEA-fed MFC was superior in all aspects. Power density of 2.7Wm^-3 was obtained by LEA-fed MFCs which is 145% and 260% higher than FP MFC and control MFC respectively. The volumetric algae productivity of 0.028kgm^-3day^-1 in cathode chamber was achieved. The system was able to generate 0.0136kWhKg^-1CODday^-1 of electric energy and 0.0782kWhm^-3day^-1 of algal oil energy. The proposed system is a net energy producer which does not rely heavily on the external supply of electron donor substrates.