Over the past years, several insect species have gained increased attention as feedstock for food, feed, and industrial applications. One such species is Hermetia illucens, whose larvae can convert low-value organic waste into valuable fat-and protein-rich biomass. Previous research on extracting their lipids, proteins, and chitin has repeatedly focused on one life stage, while in practice different life stages coexist in the same rearing batch. In this study, the feasibility of the sequential extraction of said components from the larval, prepupal, and pupal stage of H. illucens was investigated. Additionally, the chemical composition of the life stages and their extracts was analysed. Following the lipid extraction with petroleum ether, insect proteins were extracted via solubilisation at pH 11.0 and precipitation at pH 4.0. This procedure delivered protein recoveries ranging between 27-57 % for the three life stages, with the extracts having high protein contents (85-98 %). After protein extraction, the residual impure chitin was treated sequentially with HCl and NaOH for further purification. No residual amino acids were detected by UPLC analysis of the purified chitin, which showed acetylation degrees of ± 90 %. Overall, it was concluded that the extraction procedure is indeed suitable for all investigated life stages of H. illucens, allowing for the extraction high-value biomolecules for use in industrial applications.

HighlightsEnzymes are highly advantageous for consistent retting of flax aiming at composite applications.Pectinase enzymes play a major role in releasing fibers from the bast.Compromise between properties of enzymatically extracted fibers and composite performance.Recovery of enzymes important in view of overall process economy.

Saccharomyces cerevisiae is the organism of choice for many food and beverage fermentations because it thrives in high-sugar and high-ethanol conditions. However, the conditions encountered in bioethanol fermentation pose specific challenges, including extremely high sugar and ethanol concentrations, high temperature, and the presence of specific toxic compounds. It is generally considered that exploring the natural biodiversity of Saccharomyces strains may be an interesting route to find superior bioethanol strains and may also improve our understanding of the challenges faced by yeast cells during bioethanol fermentation. In this study, we phenotypically evaluated a large collection of diverse Saccharomyces strains on six selective traits relevant for bioethanol production with increasing stress intensity. Our results demonstrate a remarkably large phenotypic diversity among different Saccharomyces species and among S. cerevisiae strains from different origins. Currently applied bioethanol strains showed a high tolerance to many of these relevant traits, but several other natural and industrial S. cerevisiae strains outcompeted the bioethanol strains for specific traits. These multitolerant strains performed well in fermentation experiments mimicking industrial bioethanol production. Together, our results illustrate the potential of phenotyping the natural biodiversity of yeasts to find superior industrial strains that may be used in bioethanol production or can be used as a basis for further strain improvement through genetic engineering, experimental evolution, or breeding. Additionally, our study provides a basis for new insights into the relationships between tolerance to different stressors.

The application of enzymes as alternative to dew retting of flax was studied in correlation to the characteristics of composites reinforced with these natural fibers. Fiber fineness and mechanical properties of biocomposites were evaluated. Furthermore, moisture absorption by biocomposites was studied and fracture surfaces were investigated using Scanning Electron Microscopy. Compared to dew retted fiber composites, improvements in mechanical performance can be observed for composites impregnated with fibers extracted after enzymatic treatments. All enzymatic treatments resulted in finer fibers than green fibers and led to biocomposites with a reduced equilibrium moisture content and lower diffusion coefficient. This study illustrates the high potential of enzymatic retting, in particular with polygalacturonase. Also, the manual extraction procedure used, produced fibers with an E-modulus up to 84 GPa and strength up to 800 MPa, likely due to reduced fiber damage, which illustrates the hidden potential of flax fibers.

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