Ultrasound, microwave and enzyme-assisted multiproduct biorefinery of Ascophyllum nodosum

This study investigated the multiproduct (fucoidans, β-glucans, proteins, carotenoids, fatty acids, amino acids and polyphenols) valorization of the invasive macroalgae Ascophyllum nodosum within a green biorefinery concept using ultrasound (US), microwave (MW) treatment followed by supercritical CO2 (SC-CO2) with co-solvent and enzymatic extraction. Water and 50% aqueous ethanol were used as green extraction solvents. The extraction methods using 50% ethanol as extraction solvent improved the yields of phenolic compounds and glucan and enhanced in vitro antioxidant activity. The characterization of SC-CO2 extracts revealed that pretreatment with US and MW improved the 2-fold yield of carotenoids, total phenolics and fatty acids. However, US/MW pretreatment and enzymatic extraction did not improve the yields of proteins and free amino acids. Overall, using concurrent green US/MW-assisted extraction methods enhanced the yields of the bioactive compounds in a short duration and provided extracts with a better antioxidant capacity in the field of food applications.

Recovery of Protein from Industrial Hemp Waste (Cannabis sativa, L.) Using High-Pressure Processing and Ultrasound Technologies

Hemp seeds are currently used mainly for oil extraction, generating waste that could be potentially exploited further as a source of proteins and other bioactives. This study aims to valorise hemp waste (Cannabis sativa, L.) from previous oil extraction as a source of protein by analysing the effect of high-pressure processing (HPP) pre-treatments (0-600 MPa; 4-8 min) combined with conventional or ultrasound-assisted extraction (UAE) methods on protein recovery/purity, amino acid composition, and protein structure. Overall, maximum protein recovery (≈62%) was achieved with HPP (200 MPa, 8 min) with UAE. The highest protein purity (≈76%) was achieved with HPP (200 MPa, 4 min) with UAE. Overall, UAE improved the extraction of all amino acids compared to conventional extraction independently of HPP pre-treatments. Arg/Lys ratios of the protein isolates ranged between 3.78 and 5.34, higher than other vegetable protein sources. SDS-PAGE did not show visible differences amongst the protein isolates. These results seem to indicate the advantages of the use of UAE for protein recovery in the food industry and the need for further studies to optimise HPP/UAE for an accurate estimation of processing costs and their effects on the composition and structure of proteins to contribute further to the circular economy.

Effect of solvent composition on the extraction of proteins from hemp oil processing stream

BACKGROUND

Hempseed meal, a by-product of the hempseed oil processing stream, is a potential alternative source for food proteins. Efficient extraction of proteins from hempseed meal is challenging owing to differences in the structure and solubility of various protein fractions present in the seed. In the present study, protein was extracted from hempseed meal using four different solvents, including aqueous NaOH, KOH, NaHCO₃ and NaCl, at four different concentrations with the aim of improving the recovery of protein fractions rich in essential amino acids.

RESULTS

Extraction using alkaline solvents provided superior protein recovery (60-78%) compared with NaCl solution and control extractions (20-48% and 21%, respectively). The concentration of alkali or salt (0.25-1 mol L^-1 ) had a minor but significant impact on the yield. Amino acid composition analysis revealed that hempseed meal contains 24% (54.5 ± 0.19 mg g^-1 ) essential amino acids of total amino acids, and extraction with NaOH, KOH, NaHCO₃ or NaCl did not improve the selective extraction of essential amino acids compared to control experiments. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis allowed the identification of edestin and albumin in the extracts obtained with NaHCO₃ and NaCl solvents, with results further showing that the type of extraction solvent influences protein extraction selectivity.

CONCLUSION

Although alkali solvents provide superior extraction yields, extraction with water resulted in extracts containing the highest proportion of proteins bearing essential amino acids. According to the results of SDS-PAGE, extraction using alkali solvents induced protein crosslinking. © 2022 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Influence of molecular weight fractionation on the antimicrobial and anticancer properties of a fucoidan rich-extract from the macroalgae Fucus vesiculosus

The objective of this study was to investigate the antimicrobial and anticancer properties of a fucoidan extract and subsequent fractions isolated from the macroalgae Fucus vesiculosus. The fractions obtained (>300 kDa, <300 kDa, <100 kDa, <50 kDa and <10 kDa) could inhibit the growth of B. subtilis, E. coli, L. innocua and P. fluorescens when assayed at concentrations between 12,500 and 25,000 ppm. The bacterial growth was monitored by optical density (OD) measurements (600 nm, 24 h) at 30 °C or 37 °C, depending upon on the strain used. The extracted fractions were also tested for cytotoxicity against brain glioblastoma cancer cells using the Alamar Blue assay for 24 h, 48 h and 6 days. The >300 kDa fraction presented the lowest IC50 values (0.052% - 24 h; 0.032% - 6 days). The potential bioactivity of fucoidan as an antimicrobial and anticancer agent was demonstrated in this study. Hence, the related mechanisms of action should be explored in a near future.

Antimicrobials from Seaweeds for Food Applications

The exponential growth of emerging multidrug-resistant microorganisms, including foodborne pathogens affecting the shelf-life and quality of foods, has recently increased the needs of the food industry to search for novel, natural and eco-friendly antimicrobial agents. Macroalgae are a bio-diverse group distributed worldwide, known to produce multiple compounds of diverse chemical nature, different to those produced by terrestrial plants. These novel compounds have shown promising health benefits when incorporated into foods, including antimicrobial properties. This review aims to provide an overview of the general methods and novel compounds with antimicrobial properties recently isolated and characterized from macroalgae, emphasizing the molecular pathways of their antimicrobial mechanisms of action. The current scientific evidence on the use of macroalgae or macroalgal extracts to increase the shelf-life of foods and prevent the development of foodborne pathogens in real food products and their influence on the sensory attributes of multiple foods (i.e., meat, dairy, beverages, fish and bakery products) will also be discussed, together with the main challenges and future trends of the use of marine natural products as antimicrobials.

Noninvasive measurement of steroid hormones in zebrafish holding-water

Zebrafish (Danio rerio) has recently emerged as a new animal model in neuroendocrinology and behavior (e.g., stress physiology and ecotoxicology studies). In these areas, the concentrations of steroid hormones in the blood are often used to study the endocrinological status of individuals. However, due to the small body size of zebrafish, blood sampling is difficult to perform and the amount of plasma obtained per sample for assaying hormones is very small (ca. 1-5 μL), and therefore most studies have been using whole-body hormone concentrations, which implies sacrificing the individuals and hampers sequential sampling of the same individual. Here a noninvasive method to assay steroid hormones from zebrafish holding-water, based on the fact that steroids are released into the fish holding-water through the gills by passive diffusion, is validated. Cortisol and the androgen 11-ketotestosterone (KT) were measured in water samples and compared to plasma levels in the same individuals. Cortisol released to holding-water correlates positively with plasma concentrations, but there was a lack of correlation between KT water and circulating levels. However, KT levels showed a highly significant sex difference that can be used to noninvasively sex individuals. An ACTH challenge test demonstrated that an induced increase in circulating cortisol concentration can be reliably detected in holding-water levels, hence attesting the responsiveness of holding-water levels to fluctuations in circulating levels.