Challenges in the Application of Circular Economy Models to Agricultural By-Products: Pesticides in Spain as a Case Study.

The income and residue production from agriculture has a strong impact in Spain. A circular economy and a bioeconomy are two alternative sustainable models that include the revalorization of agri-food by-products to recover healthy biomolecules. However, most crops are conventional, implying the use of pesticides. Hence, the reutilization of agri-food by-products may involve the accumulation of pesticides. Even though the waste-to-bioproducts trend has been widely studied, the potential accumulation of pesticides during by-product revalorization has been scarcely assessed. Therefore, in this study, the most common pesticides found in eight highly productive crops in Spain are evaluated according to the available published data, mainly from EFSA reports. Among these, oranges, berries and peppers showed an increasing tendency regarding pesticide exceedances. In addition, the adverse effects of pesticides on human and animal health and the environment were considered. Finally, a safety assessment was developed to understand if the reutilization of citrus peels to recover ascorbic acid (AA) would represent a risk to human health. The results obtained seem to indicate the safety of this by-product to recover AA concentrations to avoid scurvy (45 mg/day) and improve health (200 mg/day). Therefore, this work evaluates the potential risk of pesticide exposure through the revalorization of agri-food by-products using peels from citruses, one of the major agricultural crops in Spain, as a case study.

Kinetic Extraction of Fucoxanthin from Undaria pinnatifida Using Ethanol as a Solvent.

Fucoxanthin (Fx) has been proven to exert numerous biological properties, which makes it an interesting molecule with diverse industrial applications. In this study, the kinetic behavior of Fx was studied to optimize three variables: time (t-3 min to 7 days), temperature (T-5 to 85 °C), and concentration of ethanol in water (S-50 to 100%, v/v), in order to obtain the best Fx yield from Undaria pinnatifida using conventional heat extraction. The Fx content (Y1) was found through HPLC-DAD and expressed in µg Fx/g of algae sample dry weight (AS dw). Furthermore, extraction yield (Y2) was also found through dry weight analysis and was expressed in mg extract (E)/g AS dw. The purity of the extracts (Y3) was found and expressed in mg Fx/g E dw. The optimal conditions selected for Y1 were T = 45 °C, S = 70%, and t = 66 min, obtaining ~5.24 mg Fx/g AS; for Y2 were T = 65 °C, S = 60%, and t = ~10 min, obtaining ~450 mg E/g AS; and for Y3 were T = 45 °C, S = 70%, and t = 45 min, obtaining ~12.3 mg Fx/g E. In addition, for the selected optimums, a full screening of pigments was performed by HPLC-DAD, while phenolics and flavonoids were quantified by spectrophotometric techniques and several biological properties were evaluated (namely, antioxidant, antimicrobial, and cholinesterase inhibitory activity). These results could be of interest for future applications in the food, cosmetic, or pharmaceutical industries, as they show the Fx kinetic behavior and could help reduce costs associated with energy and solvent consumption while maximizing the extraction yields.

Emerging Strategies to Combat Methicillin-resistant Staphylococcus aureus (MRSA): Natural Agents with High Potential.

Infectious diseases have always been a concern for human health, responsible for numerous pandemics throughout history. Even with the advancement of medicine, new infectious diseases have been discovered over the years, requiring constant effort in medical research to avoid future problems. Like the emergence of new diseases, the increase in resistance of certain bacterial strains also becomes a concern, carried out through the misuse of antibiotics, generating the adaptation of certain microorganisms. Worldwide, the resistance developed by several bacterial strains is growing exponentially, creating awareness and developing novel strategies to control their evolution a mandatory research topic. Methicillin-resistant Staphylococcus aureus (MRSA) is an example of a bacterial strain that causes serious and mortal infections. The fact is that this bacterial strain started to develop resistance against commonly used antibiotics, first to penicillin and against methicillin. Thus, the treatment against infections caused by MRSA is limited and difficult due to its capacity to develop defense mechanisms against the antibiotic's action. Given the urgency to find new alternatives, the scientific community has been developing interesting research regarding the exploitation of natural resources to discover bioactive molecules that are able to inhibit/kill MRSA. In this sense, several natural matrices, namely plants, have shown great potential against MRSA, due to the presence of phenolic compounds, molecules with high antimicrobial capacity due to their chemical structure and arrangement.

Machine Learning to Predict the Adsorption Capacity of Microplastics.

Nowadays, there is an extensive production and use of plastic materials for different industrial activities. These plastics, either from their primary production sources or through their own degradation processes, can contaminate ecosystems with micro- and nanoplastics. Once in the aquatic environment, these microplastics can be the basis for the adsorption of chemical pollutants, favoring that these chemical pollutants disperse more quickly in the environment and can affect living beings. Due to the lack of information on adsorption, three machine learning models (random forest, support vector machine, and artificial neural network) were developed to predict different microplastic/water partition coefficients (log Kd) using two different approximations (based on the number of input variables). The best-selected machine learning models present, in general, correlation coefficients above 0.92 in the query phase, which indicates that these types of models could be used for the rapid estimation of the absorption of organic contaminants on microplastics.

Single-Cell Proteins Obtained by Circular Economy Intended as a Feed Ingredient in Aquaculture.

The constant increment in the world's population leads to a parallel increase in the demand for food. This situation gives place the need for urgent development of alternative and sustainable resources to satisfy this nutritional requirement. Human nutrition is currently based on fisheries, which accounts for 50% of the fish production for human consumption, but also on agriculture, livestock, and aquaculture. Among them, aquaculture has been pointed out as a promising source of animal protein that can provide the population with high-quality protein food. This productive model has also gained attention due to its fast development. However, several aquaculture species require considerable amounts of fish protein to reach optimal growth rates, which represents its main drawback. Aquaculture needs to become sustainable using renewable source of nutrients with high contents of proteins to ensure properly fed animals. To achieve this goal, different approaches have been considered. In this sense, single-cell protein (SCP) products are a promising solution to replace fish protein from fishmeal. SCP flours based on microbes or algae biomass can be sustainably obtained. These microorganisms can be cultured by using residues supplied by other industries such as agriculture, food, or urban areas. Hence, the application of SCP for developing innovative fish meal offers a double solution by reducing the management of residues and by providing a sustainable source of proteins to aquaculture. However, the use of SCP as aquaculture feed also has some limitations, such as problems of digestibility, presence of toxins, or difficulty to scale-up the production process. In this work, we review the potential sources of SCP, their respective production processes, and their implementation in circular economy strategies, through the revalorization and exploitation of different residues for aquaculture feeding purposes. The data analyzed show the positive effects of SCP inclusion in diets and point to SCP meals as a sustainable feed system. However, new processes need to be exploited to improve yield. In that direction, the circular economy is a potential alternative to produce SCP at any time of the year and from various cost-free substrates, almost without a negative impact.

Fucoxanthin's Optimization from Undaria pinnatifida Using Conventional Heat Extraction, Bioactivity Assays and In Silico Studies.

Brown macroalgae are a potential source of natural pigments. Among them, Undaria pinnatifida is recognized for its high concentration of fucoxanthin (Fx), which is a pigment with a wide range of bioactivities. In this study, three independent parameters were optimized for conventional heat extraction (CHE) to maximize the recovery of Fx from Undaria pinnatifida. Optimal conditions (temperature = 45 °C, solvent = 70%, and time = 61 min) extracted 5.1 mg Fx/g dw. Later, the bioactivities of the Fx-rich extracts (antioxidant, antimicrobial, and neuroprotective) were assessed using in vitro and in silico approaches. In vitro assays indicated that Fx has a strong antioxidant capacity and even stronger antimicrobial activity against gram-positive bacteria. This data was supported in silico where Fx established a high binding affinity to DR, a Staphylococcus aureus protein, through aa ALA-8, LEU-21, and other alkane interactions. Finally, the in vitro enzymatic inhibition of AChE using Fx, was further supported using docking models that displayed Fx as having a high affinity for aa TYR72 and THR 75; therefore, the Fx extraction behavior explored in this work may reduce the costs associated with energy and solvent consumption. Moreover, this paper demonstrates the efficiency of CHE when recovering high amounts of Fx from Undaria pinnatifida. Furthermore, these findings can be applied in different industries.

Benefits and Drawbacks of Ultrasound-Assisted Extraction for the Recovery of Bioactive Compounds from Marine Algae.

The increase in life expectancy has led to the appearance of chronic diseases and interest in healthy aging, in turn promoting a growing interest in bioactive compounds (BCs) and functional ingredients. There are certain foods or products rich in functional ingredients, and algae are one of them. Algae consumption has been nominal in Europe until now. However, in recent years, it has grown significantly, partly due to globalization and the adoption of new food trends. With the aim of obtaining BCs from foods, multiple methods have been proposed, ranging from conventional ones, such as maceration or Soxhlet extraction, to more innovative methods, e.g., ultrasound-assisted extraction (UAE). UAE constitutes a novel method, belonging to so-called green chemistry, that enables the extraction of BCs requiring lower amounts of solvent and energy costs, preserving the integrity of such molecules. In recent years, this method has been often used for the extraction of different BCs from a wide range of algae, especially polysaccharides, such as carrageenans and alginate; pigments, including fucoxanthin, chlorophylls, or ß-carotene; and phenolic compounds, among others. In this way, the application of UAE to marine algae is an efficient and sustainable strategy to pursue their deep characterization as a new source of BCs, especially suitable for vegetarian and vegan diets.

Bee Venom: An Updating Review of Its Bioactive Molecules and Its Health Applications.

Bee venom (BV) is usually associated with pain since, when humans are stung by bees, local inflammation and even an allergic reaction can be produced. BV has been traditionally used in ancient medicine and in acupuncture. It consists of a mixture of substances, principally of proteins and peptides, including enzymes as well as other types of molecules in a very low concentration. Melittin and phospholipase A2 (PLA2) are the most abundant and studied compounds of BV. Literature of the main biological activities exerted by BV shows that most studies focuses on the comprehension and test of anti-inflammatory effects and its mechanisms of action. Other properties such as antioxidant, antimicrobial, neuroprotective or antitumor effects have also been assessed, both in vitro and in vivo. Moreover, human trials are necessary to confirm those clinical applications. However, notwithstanding the therapeutic potential of BV, there are certain problems regarding its safety and the possible appearance of adverse effects. On this perspective, new approaches have been developed to avoid these complications. This manuscript is aimed at reviewing the actual knowledge on BV components and its associated biological activities as well as the latest advances on this subject.