► Cheese whey was used as carbon source for Chlorella vulgaris growth. ► Mixotrophic microalgae grew faster than photoautotrophic cells. ► Maximum starch productivity was achieved under mixotrophic ...conditions. ► Highest pigment content (0.74%) was obtained in the photoautotrophic culture.
Growth parameters and biochemical composition of the green microalga Chlorella vulgaris cultivated under different mixotrophic conditions were determined and compared to those obtained from a photoautotrophic control culture. Mixotrophic microalgae showed higher specific growth rate, final biomass concentration and productivities of lipids, starch and proteins than microalgae cultivated under photoautotrophic conditions. Moreover, supplementation of the inorganic culture medium with hydrolyzed cheese whey powder solution led to a significant improvement in microalgal biomass production and carbohydrate utilization when compared with the culture enriched with a mixture of pure glucose and galactose, due to the presence of growth promoting nutrients in cheese whey. Mixotrophic cultivation of C. vulgaris using the main dairy industry by-product could be considered a feasible alternative to reduce the costs of microalgal biomass production, since it does not require the addition of expensive carbohydrates to the culture medium.
The concept of a biorefinery that integrates processes and technologies for biomass conversion demands efficient utilization of all components. Hydrothermal processing is a potential clean technology ...to convert raw materials such as lignocellulosic materials and aquatic biomass into bioenergy and high added-value chemicals. In this technology, water at high temperatures and pressures is applied for hydrolysis, extraction and structural modification of materials. This review is focused on providing an updated overview on the fundamentals, modelling, separation and applications of the main components of lignocellulosic materials and conversion of aquatic biomass (macro- and micro- algae) into value-added products.
Among the most important factors influencing beer quality is the presence of well-adjusted amounts of higher alcohols and esters. Thus, a heavy body of literature focuses on these substances and on ...the parameters influencing their production by the brewing yeast. Additionally, the complex metabolic pathways involved in their synthesis require special attention. More than a century of data, mainly in genetic and proteomic fields, has built up enough information to describe in detail each step in the pathway for the synthesis of higher alcohols and their esters, but there is still place for more. Higher alcohols are formed either by anabolism or catabolism (Ehrlich pathway) of amino acids. Esters are formed by enzymatic condensation of organic acids and alcohols. The current paper reviews the up-to-date knowledge in the pathways involving the synthesis of higher alcohols and esters by brewing yeasts. Fermentation parameters affecting yeast response during biosynthesis of these aromatic substances are also fully reviewed.
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•Potential use of algal proteins as sustainable alternative to animal-based proteins.•Algae-based foods placed on global market.•Strategies to enhance protein content of macro- and ...microalgae.•Nutritional and functional properties of algal biomass and its protein extracts.•Integrated production of algal proteins towards “greener” process approaches.
Animal-based proteins are the most consumed worldwide given their well-balanced nutritional composition. However, the growing demand for animal proteins will not be sustainable due to their low conversion efficiency and high environmental footprint. Specific consumers’ dietary restrictions and modern trends emphasize the importance of finding alternative sustainable non-animal sources to meet future food (and, in particular, protein) global needs. Algal biomass is considered a relevant alternative, presenting advantages over terrestrial biomass such as higher growth rate, low water consumption, no competition for arable land, carbon–neutral emissions, and production of numerous bioactive compounds. This review provides an overview of recent research advances on algae as source of proteins, including production strategies from relevant protein-producing species. Particular emphasis will be given to algae protein current applications and forthcoming challenges of their use. Nutritional and functional aspects of algae biomass or its protein-enriched fractions will be overviewed.
Corncob was successively pretreated by liquid hot water (LHW) and ethanol organosolv (EO) in an integrated process. LHW was performed at 200 °C for 30 min, and EO was performed using uncatalyzed ...ethanol–water solutions, according to a design of experiments. The effects of the most influential operational variables (ethanol concentration, temperature and time) on yield and chemical composition of the fractions were assessed. Results showed the factor with the greatest effect was ethanol concentration (p < 0.05), leading to a high-purity lignin (86.7%–93.1%) with a total phenolic content of around 25 mg GAE/g. Moreover, the solids recovered from the high ethanol concentration conditions presented the lowest lignin contents (15.4%–17.2%) with good preservation of cellulose (82.5%–88.6% of glucans). The lignin antioxidant capacity showed that all lignin samples presented radical scavenging activity (IC50 of 0.17 mg/mL and 0.016 mg/mL on DPPH (2,2‑diphenyl‑1‑picrylhydrazyl) and ABTS (2,2′‑azino‑bis(3‑ethylbenzothiazoline‑6‑sulphonic acid) assays, respectively) with values close to the commercial antioxidant BHT. Moreover, the chemical (FTIR) and thermal (DSC and TGA) characterization showed lignins with similar properties that were compared with lignin from direct ethanol organosolv process. Results showed that the integrated process of LHW-EO was the most effective way to obtain lignin with high purity and antioxidant capacity.
•The integrated process was more effective in lignin extraction than the direct organosolv process;•The integrated process led to a high purity lignin and a good preservation of the cellulose fraction;•The integrated process recovered lignin with enhanced antioxidant capacity.
Micro- and nanoencapsulation is an emerging technology in the food field that potentially allows the improvement of food quality and human health. Bio-based delivery systems of bioactive compounds ...have a wide variety of morphologies that influence their stability and functional performance. The incorporation of bioactive compounds in food products using micro- and nano-delivery systems may offer extra health benefits, beyond basic nutrition, once their encapsulation may provide protection against undesired environmental conditions (e.g., heat, light and oxygen) along the food chain (including processing and storage), thus improving their bioavailability, while enabling their controlled release and target delivery. This review provides an overview of the bio-based materials currently used for encapsulation of bioactive compounds intended for food applications, as well as the main production techniques employed in the development of micro- and nanosystems. The behavior of such systems and of bioactive compounds entrapped into, throughout in vitro gastrointestinal systems, is also tracked in a critical manner. Comparisons between various in vitro digestion systems (including the main advantages and disadvantages) currently in use, as well as correlations between the behavior of micro- and nanosystems studied through in vitro and in vivo systems were highlighted and discussed here for the first time. Finally, examples of bioactive micro- and nanosystems added to food simulants or to real food matrices are provided, together with a revision of the main challenges for their safe commercialization, the regulatory issues involved and the main legislation aspects.
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•Micro- and nanoencapsulation is an emerging technology in the food industry.•Novel delivery systems for food applications can be produced by bio-based materials.•Design of bio-based delivery systems can be tailored by processing conditions.•Bio-based delivery systems allow incorporation of bioactives offering extra benefits.•In vitro models are crucial to understand the behavior of bio-based delivery systems.
Aiming at the enhancement of food products' nutritional and health value, the incorporation of nutraceuticals has attracted increasing interest in the last years. However, they often exhibit low ...water solubility and stability, limiting their direct incorporation into food products. Also, they show very low bioavailability due to limited bioaccessibility, poor absorption and/or chemical transformation within the gastrointestinal tract. This renders their health benefits extremely difficult to be realized by the consumers.
In the present review the recent innovations regarding the formulation and design of bio-based micro and nano-delivery systems to encapsulate nutraceuticals is discussed; it also gives an overview of the challenges associated to their development; and highlights some strategies to enhance nutraceuticals' bioavailability. An insight about delivery systems' potential toxicity (in particular at nano-scale) is also provided.
Recent developments in the design of bio-based delivery systems offer the possibility of stabilizing and enhancing nutraceuticals' functionality within food products. In fact, different strategies can be used to enhance nutraceuticals' bioavailability: i) nano-delivery systems, besides showing a huge potential for the protection of valuable nutraceuticals during food processing/digestion, can be used to increase their bioavailability; ii) absorption enhancement technologies have been successfully used to increase nutraceuticals' membrane permeation; and iii) excipient foods have been shown to improve nutraceuticals' biological activity. However, the application of these enabling technologies to food is hindered by very pertinent issues that can be summarized in the effective preservation/maximization of the nutraceuticals' bioactivity and safety, once inside the human body.
•Delivery systems allow nutraceuticals' protection and their incorporation in foods.•Bio-based delivery systems can be specifically designed to enhance nutraceuticals' bioavailability.•Bioavailability enhancement strategies include nano-delivery systems, absorption enhancers and excipient foods.•It is crucial to evaluate the safety of nano-delivery systems in food.•Development of delivery systems that provide nutraceuticals' greatest functionality and safety remains a challenge.
•CO2 fixation rate by Chlorella vulgaris was optimized.•Growth parameters were affected by CO2 concentration and aeration rate.•Biochemical composition of algae did not change under different growth ...conditions.
Biofixation of CO2 by microalgae has been recognized as an attractive approach to CO2 mitigation. The main objective of this work was to maximize the rate of CO2 fixation (RCO2) by the green microalga Chlorella vulgaris P12 cultivated photoautotrophically in bubble column photobioreactors under different CO2 concentrations (ranging from 2% to 10%) and aeration rates (ranging from 0.1 to 0.7vvm). Results showed that the maximum RCO2 (2.22gL−1d−1) was obtained by using 6.5% CO2 and 0.5vvm after 7days of cultivation at 30°C. Although final biomass concentration and maximum biomass productivity of microalgae were affected by the different cultivation conditions, no significant differences were obtained in the biochemical composition of microalgal cells for the evaluated levels of aeration and CO2. The present study demonstrated that optimization of microalgal cultivation conditions can be considered a useful strategy for maximizing CO2 bio-mitigation by C. vulgaris.
•PHA present different biodegradation behaviour in different soil environments.•The blend of PHA with other materials, can change their biodegradation potential.•Microorganisms are the main ...responsible for PHA biodegradation in soil.
Polyhydroxyalkanoates (PHAs) are polymers with widespread applications, from medical devices to packaging. PHAs can be biodegradable in natural environments, such as soil, but the blend of PHA with other materials can change the polymer properties and consequently affect the biodegradation process. The composition of the microbial communities in soil also significantly affects the biodegradation, but other factors such as temperature, pH, and soil moisture, can also be determinant. These ecological and physic/chemical factors change in different seasons and in different soil layers. It is essential to know how these factors influence the PHAs’ biodegradation to understand the impact of PHAs in nature. This review compiles the results on PHA polymers and PHA blends biodegradation, with focus on laboratory tests. The main factors affecting PHA's biodegradation in soil, both in laboratory tests and in the environment are also discussed.
•Process conditions affect the mean droplet diameter.•Anionic nanoemulsions droplet diameter decreased with the increase in the homogenization pressure.•Anionic nanoemulsion is stable against ...creaming after 1year of storage.
This work evaluates the influence of the type of surfactant (Tween 20, SDS and DTAB) and processing conditions on the stability of oil-in-water nanoemulsions, measured in terms of hydrodynamic diameter (Hd), polydispersity index (PdI) and zeta potential (Zp). Nanoemulsions were prepared using high-pressure homogenization based on a 24 level factorial design. Results show that processing parameters such as homogenization pressure, surfactant concentrations and oil:water ratio significantly affected the values of Hd and PdI of nanoemulsions. The value of Hd of anionic nanoemulsions decreased (from 177 to 128nm) with the increase of the homogenization pressure. The increase in the surfactant concentration and the decrease of the oil:water ratio lead to a decrease of Hd for the cationic nanoemulsions (from 198 to 135nm). The increase of the oil:water ratio lead to a decrease of Hd for the non-ionic nanoemulsions (from 341 to 171nm); this is contrary to the usual assumption that higher content in oil results in higher values of Hd. Those nanoemulsions showed a good kinetic stability (evaluated after centrifugation, heating–cooling cycles and thermal stress) upon measuring the Hd during 28 and 35days of storage, without visual evidence of creaming and phase separation. After one year of storage the nanoemulsions produced with the anionic surfactant remained kinetically stable, without visual evidence of creaming and/or phase separation.
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