Physicochemical structure of chitin in the developing stages of black soldier fly

Turning black soldier fly rearing by-products into valuable materials: Valorisation through chitin and chitin nanocrystals production

The industry of insect-based proteins as feed and food products has been encountering a huge development since the last decade, and industrial-scale factories are now arising worldwide. Among all the species studied, Black Soldier Fly is one of the most promising and farmed. This rearing activity generates several by-products in the form of chitin-rich biomass that can be valorised to keep a virtuous production cycle embedded in the scope of the bioeconomy. Herein, we report the isolation of chitin and, for the first time, chitin nanocrystals (ChNCs) from all the BSF rearing by-products, i.e., moults (larval exuviae, puparium) and dead adults. Extraction yields, were dependent on the type of by-products and ranged from 5.8 % to 20.0 %, and the chemical structure of the extracts exhibited typical features of α-chitin, confirmed by FTIR, NMR, XRD and TGA analysis. Both STEM in SEM and AFM analysis confirmed the isolation of chitin nanocrystals presenting a rod-like morphology. The average nanocrystal height estimated by AFM ranged from 13 to 27 nm depending on the by-product sample. The following results highlighted the potential of BSF rearing by-products, promoting an approach to valorise those industrial waste and paving the way towards insect-based biorefinery.

Eryngo essential oil nanoemulsion stabilized by sonicated-insect protein isolate: An innovative edible coating for strawberry quality and shelf-life extension

New bioactive coatings with eryngo essential oil (EEO) nanoemulsions stabilized by ultrasonically-treated lesser mealworm protein isolate (LMPI) were developed to extend strawberry shelf life and quality. EEO due to high carvone (43.03 %), phenolics (87.45 mg gallic acid equivalent/g), flavonoids (13.56 mg quercetin equivalent/g), and carotenoids (635.07 mg/kg) contents exhibited a significant antioxidant activity comparable to ascorbic acid (AA) and BHT. Nanoemulsions stabilized with 9 % sonicated LMPI showed smaller droplet size, higher negative ζ-potential, and greater stability, turbidity, and encapsulation efficiency of EEO compared to those stabilized with native LMPI. The FTIR spectra showed that sonicated LMPI had structural changes enhancing its emulsifying activity, with key peaks indicating the presence of hydrogen bonds, carbonyl groups, and protein conformations in both EEO and LMPI. Strawberries coated with optimal EEO-loaded nanoemulsions showed superior quality with minimal storage-dependent physicochemical, textural, color, and sensory changes compared to control samples. This edible coating also maintained higher total monomeric anthocyanin and AA contents with lower peroxidase activity during storage than EEO-based coatings. However, no significant difference in superoxide dismutase activity between samples covered by EEO and EEO-loaded nanoemulsions over 14 days of storage was found. Bioactive nanoemulsions stabilized by insect proteins would be an eco-friendly and safe approach to upholding quality standards in stored fruits and vegetables.

Physical and chemical characterization of chitin and chitosan extracted under different treatments from black soldier fly

The shell of Hermetia illucens L. contains considerable amounts of chitin, which has various biological activities. So far, few studies have focused on chitin of Hermetia illucens L. as a source of chitosan and oligosaccharides. There is great potential for utilizing Hermetia illucens L. chitin to produce chitosan films in biomaterials. We studied different extraction conditions for chitin and extracted it from black soldier fly (BSF) (Hermetia illucens L.). Three processing steps were adopted: (1) demineralization, (2) deproteinization, and (3) decolorization. The chemical components (moisture, ash, protein, fat, residual protein, and residual mineral contents) and physicochemical characteristics of the chitin and chitosan extracted under these three conditions were determined. In addition, Fourier transform infrared spectroscopy and X-ray diffraction were used to analyze the extracted chitin and commercial samples, and the results showed that demineralization-deproteinization-decolorization treatments could achieve the highest chitin yield (7.18 ± 0.11 %), chitosan yield (64.22 ± 0.79 %), and the best purity (residual protein 0.56 ± 0.01 % and residual ash 0.58 ± 0.04 %), making it the best treatment method. Using this method, the residues produced from farmed BSF can be recycled and used as a new source of chitin.

In vitro antifungal activity and in vivo edible coating efficacy of insect-derived chitosan against Botrytis cinerea in strawberry

Strawberry is a perishable fruit, susceptible to development of rot by a range of fungi, in particular Botrytis cinerea. Chitosan represents an alternative to agrochemicals for improving shelf-life and fighting fungal pathogens. A chitosan-based coating derived from pupal exuviae of Hermetia illucens has been recently formulated for improving shelf-life of strawberry stored at 4 °C and mixed condition (4 °C and room temperature). The effects of a decolored (PEDEC) and not decolored (PEND) chitosan from the black soldier fly were evaluated and compared with commercial chitosans from crustaceans (CCs), in vitro and in vivo. An inhibition/reduction of fungal growth and a disturbance of normal fungal morphology were observed, being MIC of 0.5 mg mL-1 and 1 mg mL-1 and growth inhibition of 70 % and 4% for PEND and PEDEC, respectively. Both edible coatings distributed via aerograph showed equal or better potential application than CCs in controlling B. cinerea in strawberry post-harvest treated. Different effects for chitosans depended on their different molecular weight and deacetylation degree distributions, and the presence or absence of melanin pigments in their structure. PEND could act directly against the fungus, with effects predominantly associated with fungitoxic properties; PEDEC might principally provide viable alternatives, such as the elicitation of biochemical defense responses in fruits, for example through total phenols, in particular the flavonoids.

Integrated ultrasonic-transglutaminase modification of lesser mealworm protein isolate: A pioneering cobalamin delivery vehicle in gluten-free breads

A combined approach of microbial transglutaminase (MTGase) crosslinking and high-intensity ultrasound (HIU) was implemented to improve the physicochemical, rheological, structural, and thermal properties, as well as the targeted release of vitamin B12 of lesser mealworm protein isolate (LMPI)-based gels. Prolonging HIU to 60 min significantly reduced LMPIs' size, polydispersity, zeta-potential, and fluorescence intensity while increasing surface hydrophobicity, free amino (FAGs), and sulfhydryl (FSGs) groups. The MTGase-catalyzed LMPI gels effectively decreased the content of FAGs and FSGs. LMPI gels from 60 and 75 min HIU and MTGase catalysis exhibited a shear-thinning flow behavior, superior thermal stability, and improved water retention and gel strength with the most controlled release of vitamin B12 during in vitro simulated gastrointestinal digestion. Incorporating freeze-dried gel powders from 60 min HIU-treated MTGase-catalyzed LMPI and pea protein isolate into the dough of a new gluten-free bread improved physicochemical, textural, and sensory properties, with notable vitamin B12 retention rate.

Update on Chitin and Chitosan from Insects: Sources, Production, Characterization, and Biomedical Applications

Insects, renowned for their abundant and renewable biomass, stand at the forefront of biomimicry-inspired research and offer promising alternatives for chitin and chitosan production considering mounting environmental concerns and the inherent limitations of conventional sources. This comprehensive review provides a meticulous exploration of the current state of insect-derived chitin and chitosan, focusing on their sources, production methods, characterization, physical and chemical properties, and emerging biomedical applications. Abundant insect sources of chitin and chitosan, from the Lepidoptera, Coleoptera, Orthoptera, Hymenoptera, Diptera, Hemiptera, Dictyoptera, Odonata, and Ephemeroptera orders, were comprehensively summarized. A variety of characterization techniques, including spectroscopy, chromatography, and microscopy, were used to reveal their physical and chemical properties like molecular weight, degree of deacetylation, and crystallinity, laying a solid foundation for their wide application, especially for the biomimetic design process. The examination of insect-derived chitin and chitosan extends into a wide realm of biomedical applications, highlighting their unique advantages in wound healing, tissue engineering, drug delivery, and antimicrobial therapies. Their intrinsic biocompatibility and antimicrobial properties position them as promising candidates for innovative solutions in diverse medical interventions.

Valorization of Hermetia illucens breeding rejects by chitins and chitosans production. Influence of processes and life cycle on their physicochemical characteristics

Breeding of the black soldier fly is carried out to produce proteins. It is accompanied by releases during the life cycle of this insect. This work is a study of the valorization of these rejects through the production of chitins and chitosans with controlled characteristics. An extraction process is developed with an order of treatments and reaction conditions that provide chitins with high contents. These contents increase as the stages of the life cycle progress and drop for the adult. However, the exuviae chitins present organic impurities which will be eliminated at the N-deacetylation reaction for pupe and after a purification treatment for chitosan from larval stages. All these chitins have an α structure although certain physicochemical characteristics of the larval exuviae chitins are close to those presented by γ chitin. The observed shifts are linked to the effect of impurities rather than to a difference in structure. N-deacetylation of chitins makes possible the valorization of all rejects by the production of pure chitosans with high yields which retain a porous structure for the exuviae and fibrous for the adult which allow complementary applications. These chitosans are highly to completely deacetylated and their molar masses can vary depending on the process and life stage.

Pretreatment of chitin depolymerization by expansin-like protein to improve hydrolysis efficiency

Chitin is a polysaccharide similar to cellulose that contains abundant hydrogen bonds. Expansin-like proteins disrupt hydrogen bond networks, causing cellulose to swell and accelerating its degradation. We examined the effects of pretreatment with two expansin-like proteins, CxEXL22 (Arthrobotrys sp. CX1) and HcEXL (Hahella chejuensis), on chitin depolymerisation and enzymatic degradation. The efficiency of chitin degradation increased more than two-fold after pretreatment with expansin-like proteins. Following pretreatment with expansin-like proteins, chitin had a lower crystallinity index, greater d-spacing and crystallite size, and weaker hydrogen bonds, and the loosened porous microfibrils were more exposed than in untreated chitin. The rupture characterisation of crystalline chitin indicated that expansin-like proteins loosened the hydrogen bonds of the chitin polysaccharide chains, causing significant depolymerisation to expose more porous structures and enhance chitin accessibility.

Isolation and Structure Analysis of Chitin Obtained from Different Developmental Stages of the Mulberry Silkworm (Bombyx mori)

Chitin, a ubiquitous biopolymer, holds paramount scientific and economic significance. Historically, it has been primarily isolated from marine crustaceans. However, the surge in demand for chitin and the burgeoning interest in biopolymers have necessitated the exploration of alternative sources. Among these methods, the mulberry silkworm (Bombyx mori) has emerged as a particularly intriguing prospect. To isolate chitin from Bombyx mori, a chemical extraction methodology was employed. This process involved a series of meticulously orchestrated steps, including Folch extraction, demineralization, deproteinization, and decolorization. The resultant chitin was subjected to comprehensive analysis utilizing techniques such as attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), 13C nuclear magnetic resonance (NMR) spectroscopy, and wide-angle X-ray scattering (WAXS). The obtained results allow us to conclude that the Bombyx mori represents an attractive alternative source of α-chitin.

Endogenous chitinase might lead to differences in growth performance and intestinal health of piglets fed different levels of black soldier fly larva meal

This study aimed to investigate the effects of different levels of black soldier fly (BSF) replacing soybean meal (SBM) in diets on the performance and health condition of piglets. A total of 180 weaned piglets were allocated into 5 treatments: BSF0 (corn-soybean meal basal diet), BSF25 (BSF replacing 25% SBM), BSF50 (BSF replacing 50% SBM), BSF75 (BSF replacing 75% SBM) and BSF100 (BSF replacing 100% SBM). During the whole period, in comparison with BSF0, average daily gain (ADG) and average daily feed intake increased in the BSF25 and BSF50 groups, whereas ADG decreased in the BSF75 and BSF100 groups (P < 0.05). The result of quadratic fitting curve showed that piglets exhibited the highest ADG when BSF replaced around 20% SBM. Compared with BSF0, organic matter and dry matter digestibility improved in the BSF25 group, whereas ether extract digestibility decreased in the BSF100 group (P < 0.05). In comparison with BSF0, piglets from the BSF25 group showed a higher duodenal ratio of villus height to crypt depth, increased jejunal sucrase activity, serum neuropeptide Y and ghrelin levels, elevated ileal immunoglobulin (Ig) A, IgG and IgM contents and a lower leptin level, and piglets from the BSF100 group exhibited an increased relative weight of kidney (P < 0.05). However, no significant differences were observed in the expression level of tight junction proteins and chitin-degrading enzyme. Additionally, compared with BSF0, the abundance of short chain fatty acid producing bacteria such as Ruminococcaceae, Faecalibacterium and Butyricicoccus increased, and potential pathogenic bacteria decreased in piglets from the BSF25 group, whereas piglets from the BSF100 group had a greater abundance of harmful bacteria. In conclusion, BSF replacing 25% SBM in diets could improve digestive parameters, immune function and intestinal microbiota, and thus improved growth performance of piglets. However, BSF replacing 100% SBM showed an adverse effect on piglet performance, and the reason might be related to the limited amount of chitin-degrading enzyme.

Edible insects as emerging food products-processing and product development perspective

Edible insects (EI) are also becoming as a part of the diet due to their nutritional value and health benefits in many regions of the world. These EI are inexhaustible sources accessible by garnering from the wild with high feed conversion efficiency. Appreciating the budding of EI in justifiable food production, enlightening food security and biodiversity conversion, is promising a sufficient supply of the insect resource for future food to the world. These insects are processed to develop new products, improve organoleptic and nutritional parameters as well as the extension of shelf life. In this review, we discuss the edible insect characteristics, the potential application of EI in food industry, processing, pretreatments, drying, extraction of edible compounds like protein, lipid and chitin various food products formulation, safety regulation. Availability of broad nutritional spectrum of EI includes protein, mono and poly unsaturaturated fatty acids, amino acids, vitamins, amino aids and minerals has been used as an ingredient in development of various forms of food products such as flours in the form of whole insect powder, protein isolate, canned products, extruded products, hard candies, spreads, liquor infusion, cookies and other products.

Effects of Black Soldier Fly Larvae (Hermetia illucens Larvae) Meal on the Production Performance and Cecal Microbiota of Hens

The effects of Hermetia illucens larvae meal (HILM) as a feed supplement on production performance and cecal microflora were studied in 900 Hy-line Brown laying hens. Laying hens (60 weeks old) were randomly divided into four groups. Each group had five replicates, and each replicate had 45 hens. The control group was fed with a corn-soybean-based diet, and the experimental groups were fed with 1% HILM, 2% HILM, or 3% HILM. Results were as follows: (1) With the increase in HILM level, the laying rate increased linearly (p ≤ 0.05), and the feed/egg and cracked-egg rate decreased linearly (p ≤ 0.05). (2) Community composition analysis showed that the dominant bacteria in each group were Bacteroidetes and Firmicutes, followed by Actinobacteria and Proteobacteria, which accounted for more than 97% of 16S rRNA gene sequence of the total cecal bacteria. (3) Alpha diversity analysis at the operational taxonomic unit classification level showed that the HILM-addition groups had higher community richness and community diversity than the control group. (4) Principal co-ordinates analysis showed that the cecum samples in each group were significantly separated (p ≤ 0.05). At the phylum level, the relative abundance of Bacteroidetes in the HILM addition groups was significantly lower than that in the control group (p < 0.001), and the relative abundance of Firmicutes in the HILM addition groups was significantly higher than that in the control group (p < 0.001). In conclusion, dietary HILM supplementation had a significant effect on the production performance and cecal microflora of laying hens at the late laying period under the conditions of this experiment but had no adverse effect on the intestinal dominant flora.

Lesser mealworm (Alphitobius diaperinus L.) larvae oils extracted by pure and binary mixed organic solvents: Physicochemical and antioxidant properties, fatty acid composition, and lipid quality indices

Insect oil is one of the most sustainable lipid sources with remarkable health effects. Herein, the type of organic solvents (i.e., n-hexane, ethanol, and isopropanol) and their binary mixtures was evaluated based on the quantity (e.g., yield extraction) and quality (e.g., bioactive compounds, thermal stability, DPPH scavenging rate, fatty acid profile, and nutritional indices) of lesser mealworm oils. The oils extracted by ethanol/isopropanol and ethanol/n-hexane significantly showed the highest extraction yield and efficiency, lightness, accelerated thermal stability, phenolics, tocopherols, vitamin D, campesterol, β-sitosterol, phosphatidylinositol and phosphatic acid, linoleic acid, and hypocholesterolemic/hypercholesterolemic ratio, while these organic mixtures meaningfully extracted lipids with the lowest peroxide value, free fatty acid, and atherogenicity and thrombogenicity indices. These solvents compared to pure ones could dissolve membrane and internal lipids with the complete disintegration of external structures. The ethanol/isopropanol mixture would be a promising solvent for n-hexane substitution to extract this oil on an industrial scale.

Isolated and identified pathogenic bacteria from black soldier fly larvae with "soft rot" reared in mass production facilities and its incidence characteristics

The black soldier fly larvae (BSFL) can transform organic waste into high-end proteins, lipids, chitin, biodiesel, and melanin at an industrial scale. But scaling up of its production capacity has also posed health risks to the insect itself. In this investigation, larval "soft rot" which is occurring in mass production facilities that cause larval developmental inhibition and a certain degree of death was reported. Responsible pathogen GX6 was isolated from BSFL with "soft rot" and identified to be Paenibacillus thiaminolyticus. No obvious impact on larval growth was observed when treated with GX6 spores, whereas mortality of 6-day-old BSFL increased up to 29.33% ± 2.05% when GX6 vegetative cells (1 × 10⁶ cfu/g) were inoculated into the medium. Moreover, higher temperature further enhanced the BSFL mortality and suppressed larval development, but increasing substrate moisture showed the opposite effect. The middle intestine of infected larvae became swollen and transparent after dissection and examination. Transmission electron microscopy (TEM) observation indicated that GX6 had destroyed the peritrophic matrix and intestinal microvilli and damaged epithelial cells of larval gut. Furthermore, 16S rRNA gene sequencing analysis of intestinal samples revealed that gut microflora composition was significantly altered by GX6 infection as well. It can be noticed that Dysgonomonas, Morganella, Myroides, and Providencia bacteria became more numerous in the intestines of GX6-infected BSFL as compared to controls. This study will lay foundations for efficient control of "soft rot" and promote healthy development of the BSFL industry to contribute to organic waste management and circular economy.

Effects of partial or complete replacement of soybean meal with commercial black soldier fly larvae (Hermetia illucens) meal on growth performance, cecal short chain fatty acids, and excreta metabolome of broiler chickens

Black soldier fly larvae meal (BSFLM) is receiving great attention as a rich source of protein and antimicrobials for poultry. Therefore, we evaluated the effects of partially or completely replacing soybean meal (SBM) with commercial BSFLM on growth performance, tibia traits, cecal short chain fatty acid (SCFA) concentrations, and excreta metabolomes in broiler chickens (Gallus gallus domesticus). A total of 480 day-old male Ross × Ross 708 chicks were assigned to 6 diets (8 replicates/diet): a basal corn-SBM diet with in-feed bacitracin methylene disalicylate (BMD), a corn-SBM diet without BMD (0% BSFLM), and four diets in which the SBM was substituted with 12.5, 25, 50, and 100% BSFLM. Body weight (BW), feed intake (FI) and cumulative feed conversion ratio (cFCR) were monitored on days 14, 28, and 35. Cecal SCFA levels were determined on days 14, 28, and 35. Tibia traits and excreta metabolomes were determined on day (d) 35. On d14, birds fed 12.5 and 25% BSFLM had a similar BW, FI, and cFCR as birds fed BMD (P > 0.05). On d 35, birds fed 12.5% BSFLM had a similar BW, FI and cFCR as birds fed BMD or 0% BSFLM (P > 0.05). For each phase, birds fed 100% BSFLM had a lower BW, FI and higher cFCR than birds fed BMD or 0% BSFLM (P < 0.05). On d 35, BW decreased linearly, quadratically, and cubically with increasing levels of BSFLM (P < 0.01). Overall (d 0-35), BSFLM linearly, quadratically, and cubically decreased FI and quadratically and cubically increased cFCR (P < 0.01). Quadratic responses were observed for tibia fresh weight (P = 0.049) and ash content (P = 0.022). BSFLM did not impact cecal SCFAs levels. The excreta metabolome of birds fed 100% BSFLM clustered independently from all other groups and exhibited greater levels of putatively identified methionine, lysine, valine, glutamine, histidine and lower levels of arginine as compared to all diets. Taken together, substitution of SBM with ≤25% of BSFLM in the starter phase may be used as an alternative to BMD.

A novel chitinous nanoparticles prepared and characterized with black soldier fly (Hermetia illucens L.) using steam flash explosion treatment

This is the first report of the use of steam flash explosion (SFE) to prepare chitinous nanoparticles from black soldier fly (BSF). SFE treatment was performed at a steam pressure of 0.45 to 1.60 MPa with a holding time of 60 s. As the pressure increased, the particle size of the chitinous particles decreased. Under SFE at 1.60 MPa, chitinous nanoparticles with sizes ranging from 59 to 162 nm were produced. SEM, AFM, Raman spectroscopy, FT-IR spectroscopy, ¹H NMR, TGA, and DSC were used to characterize the BSF chitin materials. It was demonstrated that SFE treatment deacetylated chitin to obtain chitosan with 91.24 % deacetylation. In addition, the polymer backbone was maintained, and the degree of polymerization of chitosan nanoparticles was reduced. The activity of the cationic groups of chitosan nanoparticles was improved, thereby enhancing the temperature sensitivity of the polymeric material. It can be concluded that the SFE one-step processing method is a simple and efficient way to prepare homogeneous biomaterial nanoparticles. This study has implications for the development of chitosan nanomaterials for biomedical applications.

Black soldier fly, Hermetia illucens as a potential innovative and environmentally friendly tool for organic waste management: A mini-review

The application of black soldier fly (BSF), Hermetia illucens based technology to process organic wastes presents a practical option for organic waste management by producing feed materials (protein, fat), biodiesel, chitin and biofertilizer. Therefore, BSF organic wastes recycling is a sustainable and cost-effective process that promotes resource recovery, and generates valuable products, thereby creating new economic opportunities for the industrial sector and entrepreneurs. Specifically, we discussed the significance of BSF larvae (BSFL) in the recycling of biowaste. Despite the fact that BSFL may consume a variety of wastes materials, whereas, certain lignocellulosic wastes, such as dairy manure, are deficient in nutrients, which might slow BSFL development. The nutritional value of larval feeding substrates may be improved by mixing in nutrient-rich substrates like chicken manure or soybean curd residue, for instance. Similarly, microbial fermentation may be used to digest lignocellulosic waste, releasing nutrients that are needed for the BSFL. In this mini-review, a thorough discussion has been conducted on the various waste biodegraded by the BSFL, their co-digestion and microbial fermentation of BSFL substrate, as well as the prospective applications and safety of the possible by-products that may be generated at the completion of the treatment process. Furthermore, this study examines the present gaps and challenges on the direction to the efficient application of BSF for waste management and the commercialization of its by-products.

Fishmeal Protein Replacement by Defatted and Full-Fat Black Soldier Fly Larvae Meal in Juvenile Turbot Diet: Effects on the Growth Performance and Intestinal Microbiota

A 12-week feeding trial was conducted to investigate the effect of the same fishmeal protein level replaced by black soldier fly larvae (Hermetia illucens) meal (BSFL) with different lipid contents on the growth performance and intestinal health of juvenile turbot (Scophthalmus maximus L.) (initial body weight 12.64 g). Three isonitrogenous and isolipidic diets were formulated: fish meal-based diet (FM), diets DF and FF, in which 14% fish meal protein of the FM diet was replaced by defatted and full-fat BSFL, respectively. There were no significant differences in growth performance, intestinal morphology, and mucosal barrier function between the DF and the FM group. However, diet FF markedly reduced the growth performance, intestinal perimeter ratio, and the gene expression of anti-inflammatory cytokine TGF-β (P < 0.05). Compared to group FF, the communities of intestinal microbiota in group DF were more similar to group FM. Moreover, diet DF decreased the abundance of some potential pathogenic bacteria and enriched the potential probiotics, such as Bacillus. Diet FF obviously altered the composition of intestinal microbiota and increased the abundance of some potential pathogenic bacteria. These results suggested that the application of defatted BSFL showed more positive effects on fish growth and intestinal health than the full-fat BSFL, and the intestinal microbiota was closely involved in these effects.

The Variety of Applications of Hermetia illucens in Industrial and Agricultural Areas-Review

Hermetia illucens (Diptera: Stratiomyidae, Linnaeus, 1978), commonly known as the black soldier fly (BSF), is a saprophytic insect, which in recent years has attracted significant attention from both the scientific community and industry. The unrestrained appetite of the larvae, the ability to forage on various organic waste, and the rapid growth and low environmental impact of its breeding has made it one of the insect species bred on an industrial scale, in the hope of producing fodder or other ingredients for various animals. The variety of research related to this insect has shown that feed production is not the only benefit of its use. H. illucens has many features and properties that could be of interest from the point of view of many other industries. Biomass utilization, chitin and chitosan source, biogas, and biodiesel production, entomoremediation, the antimicrobial properties of its peptides, and the fertilizer potential of its wastes, are just some of its potential uses. This review brings together the work of four years of study into H. illucens. It summarizes the current state of knowledge and introduces the characteristics of this insect that may be helpful in managing its breeding, as well as its use in agro-industrial fields. Knowledge gaps and under-studied areas were also highlighted, which could help identify future research directions.

Monitoring Compositional Changes in Black Soldier Fly Larvae (BSFL) Sourced from Different Waste Stream Diets Using Attenuated Total Reflectance Mid Infrared Spectroscopy and Chemometrics

Black soldier fly (Hermetia illucens, L.) larvae are characterized by their ability to convert a variety of organic matter from food waste into a sustainable source of food (e.g., protein). This study aimed to evaluate the use of attenuated total reflectance (ATR) mid-infrared (MIR) spectroscopy to monitor changes in the composition as well as to classify black soldier fly larvae (BSFL) samples collected from two growth stages (fifth and sixth instar) and two waste stream diets (bread and vegetables, soy waste). The BSFL samples were fed on either a soy or bread-vegetable mix waste in a control environment (temperature 25 °C, and humidity 70%). The frass and BSFL samples harvested as fifth and sixth instar samples were analyzed using an ATR-MIR instrument where frequencies at specific wavenumbers were compared and evaluated using different chemometric techniques. The PLS regression models yield a coefficient of determination in cross-validation (R2) > 0.80 for the prediction of the type of waste used as diet. The results of this study also indicated that the ratio between the absorbances corresponding to the amide group (1635 cm−1) and lipids (2921 + 2849 cm−1) region was higher in diets containing a high proportion of carbohydrates (e.g., bread-vegetable mix) compared with the soy waste diet. This study demonstrated the ability of MIR spectroscopy to classify BSFL instar samples according to the type of waste stream used as a diet. Overall, ATR-MIR spectroscopy has shown potential to be used as tool to evaluate and monitor the development and growth of BSFL. The utilization of MIR spectroscopy will allow for the development of traceability systems for BSFL. These tools will aid in risk evaluation and the identification of hazards associated with the process, thereby assisting in improving the safety and quality of BSFL intended to be used by the animal feed industry.

Nutritional Composition of Black Soldier Fly Larvae (Hermetia illucens L.) and Its Potential Uses as Alternative Protein Sources in Animal Diets: A Review

The rapidly growing population has increased demand for protein quantities and, following a shortage of plant-based feed protein sources and the prohibition of animal-based feed protein, has forced the search for new sources of protein. Therefore, humans have turned their attention to edible insects. Black soldier fly larvae (BSFL) (Hermetia illucens L.) are rich in nutrients such as fat, protein and high-quality amino acids and minerals, making them a good source of protein. Furthermore, BSFL are easily reared and propagated on any nutrient substrate such as plant residues, animal manure and waste, food scraps, agricultural byproducts, or straw. Although BSFL cannot completely replace soybean meal in poultry diets, supplementation of less than 20% has no negative impact on chicken growth performance, biochemical indicators and meat quality. In pig studies, although BSFL supplementation did not have any negative effect on growth performance and meat quality, the feed conversion ratio (FCR) was reduced. There is obviously less research on the feeding of BSFL in pigs than in poultry, particularly in relation to weaning piglets and fattening pigs; further research is needed on the supplementation level of sows. Moreover, it has not been found that BSFL are used in ruminants, and the next phase of research could therefore study them. The use of BSFL in animal feed presents some challenges in terms of cost, availability and legal and consumer acceptance. However, this should be considered in the context of the current shortage of protein feed and the nutritional value of BSFL, which has important research significance in animal production.

Recent advances in the utilization of insects as an ingredient in aquafeeds: A review

The aquafeed industry continues to expand in response to the rapidly growing aquaculture sector. However, the identification of alternative protein sources in aquatic animal diets to replace conventional sources due to cost and sustainability issues remains a major challenge. Recently, insects have shown tremendous results as potential replacers of fishmeal in aquafeed. The present study aimed to review the utilization of insects in aquafeeds and their effects on aquatic animals' growth and feed utilization, immune response and disease resistance, and fish flesh quality and safety. While many insect species have been investigated in aquaculture, the black soldier fly (Hermetia illucens), and the mealworm (Tenebrio molitor) are the most studied and most promising insects to replace fishmeal in aquafeed. Generally, insect rearing conditions and biomass processing methods may affect the product's nutritional composition, digestibility, shelf life and required insect inclusion level by aquatic animals. Also, insect-recommended inclusion levels for aquatic animals vary depending on the insect species used, biomass processing method, and test organism. Overall, while an appropriate inclusion level of insects in aquafeed provides several nutritional and health benefits to aquatic animals, more studies are needed to establish optimum requirements levels for different aquaculture species at different stages of development and under different culture systems.

Immunomodulatory potential of black soldier fly larvae: applications beyond nutrition in animal feeding programs

Insect-derived ingredients, including whole larvae, protein-rich meal, and oil, have been extensively studied in recent years and shown to be a sustainable source of quality nutrition for virtually all animal species and life stages. In addition to the ability to use these ingredients as a source of essential nutrition, more recent research has demonstrated the potential for the immunomodulatory activity of various components of insect-derived ingredients. For all insects studied, antimicrobial peptides make up a critical part of the insects’ innate immune system and these peptides have antimicrobial efficacy when purified from hemolymph and tested in vitro. From black soldier fly larvae, in particular, lauric acid is a predominant fatty acid deposited into the insect, and lauric acid also has potential antimicrobial activity in vitro and in vivo. Finally, the chitin and chitosan components of the insect exoskeleton may modulate microbial activity in a variety of ways. In companion animals, poultry, and livestock species, insect-derived ingredients have shown the potential to reduce the impact of actual or simulated disease challenge on several parameters of animal health and well-being. This review describes the current state of knowledge of the immunomodulatory potential of insect-derived ingredients.

Antimicrobial properties of chitosan from different developmental stages of the bioconverter insect Hermetia illucens

Growing antimicrobial resistance has prompted researchers to identify new natural molecules with antimicrobial potential. In this perspective, attention has been focused on biopolymers that could also be functional in the medical field. Chitin is the second most abundant biopolymer on Earth and with its deacetylated derivative, chitosan, has several applications in biomedical and pharmaceutical fields. Currently, the main source of chitin is the crustacean exoskeleton, but the growing demand for these polymers on the market has led to search for alternative sources. Among these, insects, and in particular the bioconverter Hermetia illucens, is one of the most bred. Chitin can be extracted from larvae, pupal exuviae and dead adults of H. illucens, by applying chemical methods, and converted into chitosan. Fourier-transformed infrared spectroscopy confirmed the identity of the chitosan produced from H. illucens and its structural similarity to commercial polymer. Recently, studies showed that chitosan has intrinsic antimicrobial activity. This is the first research that investigated the antibacterial activity of chitosan produced from the three developmental stages of H. illucens through qualitative and quantitative analysis, agar diffusion tests and microdilution assays, respectively. Our results showed the antimicrobial capacity of chitosan of H. illucens, opening new perspectives for its use in the biological area.

Characterization of chitin and chitosan derived from Hermetia illucens, a further step in a circular economy process

Due to their properties and applications, the growing demand for chitin and chitosan has stimulated the market to find more sustainable alternatives to the current commercial source (crustaceans). Bioconverter insects, such as Hermetia illucens, are the appropriate candidates, as chitin is a side stream of insect farms for feed applications. This is the first report on production and characterization of chitin and chitosan from different biomasses derived from H. illucens, valorizing the overproduced larvae in feed applications, the pupal exuviae and the dead adults. Pupal exuviae are the best biomass, both for chitin and chitosan yields and for their abundance and easy supply from insect farms. Fourier-transform infrared spectroscopy, X-ray diffraction and scanning electron microscope analysis revealed the similarity of insect-derived polymers to commercial ones in terms of purity and structural morphology, and therefore their suitability for industrial and biomedical applications. Its fibrillary nature makes H. illucens chitin suitable for producing fibrous manufacts after conversion to chitin nanofibrils, particularly adults-derived chitin, because of its high crystallinity. A great versatility emerged from the evaluation of the physicochemical properties of chitosan obtained from H. illucens, which presented a lower viscosity-average molecular weight and a high deacetylation degree, fostering its putative antimicrobial properties.

Frass derived from black soldier fly larvae treatment of biodegradable wastes. A critical review and future perspectives

Inadequately treated biodegradable waste is considered an environmental, social and economic threat worldwide, which call for great attention. Waste treatment with larvae of the black soldier fly (BSF, Hermetia illucens) complies with the concepts of circular economy, as it enables the transformation of these wastes into marketable products, closing loops and promoting circularity. The processing residues of the treatment (frass) is constantly generated in waste management facilities in large volumes, and this product can be used as an organic fertilizer in agriculture, stimulating a transition to a circular economy. However, many aspects related to frass are still unknown, such as its varying composition of nutrients, microorganisms and bioactive compounds, its post-processing requirements for improved biological stabilization, its behavior in the soil and action in the plants' metabolism, among other aspects. In this review article, we highlight the potential of frass from BSF larvae treatment of biodegradable waste in the world market regarding its possible use as a fertilizer, summarize recent results with this novel product and point towards future research perspectives.

Chitin and derivative chitosan-based structures - Preparation strategies aided by deep eutectic solvents: A review

The high molecular weight of chitin, as a biopolymer, challenges its extraction due to its insolubility in the solvents. Also, chitosan, as the N-deacetylated form of chitin, can be employed as a primary material for different industries. The low mechanical stability and poor plasticity of chitosan films, as a result of incompatible interaction between chitosan and the used solvent, have limited its industrialization. Deep eutectic solvents (DESs), as novel solvents, can solve the extraction difficulties of chitin, and the low mechanical stability and weak plasticity of chitosan films. Also, DESs can be considered for the different chitosan and chitin productions, including chitin nanocrystal and nanofiber, N,N,N-trimethyl-chitosan, chitosan-based imprinted structures, and DES-chitosan-based beads and monoliths. This review aims to focus on the preparation and characterization (chemistry and morphology) of DES-chitin-based and DES-chitosan-based structures to understand the influence of the incorporation of DESs into the chitin and chitosan structure.

Chitin Determination in Residual Streams Derived From Insect Production by LC-ECD and LC-MS/MS Methods

Chitin, a biopolymer present in fungi and arthropods, is a compound of interest for various applications, such as in the agricultural and medical fields. With the recently growing interest in the development of insect farming, the availability of chitin-containing residual streams, particularly the molting skins (exuviae), is expected to increase in the near future. For application purposes, accurate quantification of chitin in these insect sources is essential. Previous studies on chitin extraction and quantification often overlooked the purity of the extracted chitin, making the outcomes inconsistent and prone to overestimation. The present study aims to determine chitin content in the exuviae of three insect species mass-reared worldwide: black soldier fly (BSF), mealworm, and house cricket. Chitin was chemically extracted using acid and alkali treatments to remove minerals and proteins. The purity of extracted chitin was evaluated by hydrolyzing the chitin into glucosamine, followed by quantitative determination of the latter using two liquid chromatography methods: electrochemical detection (ECD) and tandem mass spectrometry (MS/MS). Both methods proved accurate and precise, without the need for labor-intensive derivatization steps. Pearson's correlation and Bland-Altman plots showed that the glucosamine determination results obtained by the two methods were comparable, and there is no consistent bias of one approach vs. the other. The chitin content in extracted residues ranged between 7.9 and 18.5%, with the highest amount found in BSF puparium. In summary, the study demonstrated that (1) the residual streams of the insect farming industry have a great potential for utilization as an alternative chitin source, and (2) both LC-ECD and LC-MS/MS are reliable for the quantitative determination of glucosamine in insect chitin.

Antimicrobial Activity of Chemically and Biologically Treated Chitosan Prepared from Black Soldier Fly (Hermetia illucens) Pupal Shell Waste

Globally, the broad-spectrum antimicrobial activity of chitin and chitosan has been widely documented. However, very little research attention has focused on chitin and chitosan extracted from black soldier fly pupal exuviae, which are abundantly present as byproducts from insect-farming enterprises. This study presents the first comparative analysis of chemical and biological extraction of chitin and chitosan from BSF pupal exuviae. The antibacterial activity of chitosan was also evaluated. For chemical extraction, demineralization and deproteinization were carried out using 1 M hydrochloric acid at 100 °C for 2 h and 1 M NaOH for 4 h at 100 °C, respectively. Biological chitin extraction was carried out by protease-producing bacteria and lactic-acid-producing bacteria for protein and mineral removal, respectively. The extracted chitin was converted to chitosan via deacetylation using 40% NaOH for 8 h at 100 °C. Chitin characterization was done using FTIR spectroscopy, while the antimicrobial properties were determined using the disc diffusion method. Chemical and biological extraction gave a chitin yield of 10.18% and 11.85%, respectively. A maximum chitosan yield of 6.58% was achieved via chemical treatment. From the FTIR results, biological and chemical chitin showed characteristic chitin peaks at 1650 and 1550 cm⁻¹—wavenumbers corresponding to amide I stretching and amide II bending, respectively. There was significant growth inhibition for Escherichia coli, Bacillus subtilis,Pseudomonas aeruginosa,Staphylococcus aureus, and Candida albicans when subjected to 2.5 and 5% concentrations of chitosan. Our findings demonstrate that chitosan from BSF pupal exuviae could be a promising and novel therapeutic agent for drug development against resistant strains of bacteria.

Production of natural chitin film from pupal shell of moth: Fabrication of plasmonic surfaces for SERS-based sensing applications

Commercially available types of chitin or chitin isolate are usually in powder form and are nanofibrous in microstructure. However, the surface characteristics of natural chitin in the body of insects are currently understudied. Herein, natural chitin film was successfully produced from bio-waste of insect pupae of the Japanese giant silkworm. Two different surface morphologies of the chitin film were observed. We report for the first time a micropapillary surface structure of chitin which was observed on the dorsal side of the film. To further potential of the micropapillary structured natural chitin in sensing applications, we develop a protocol for generating a nanoscopic film of Ag using thermal evaporation. The Ag-deposited natural chitin films exhibited surface-enhanced Raman scattering (SERS) activity to an extent depending on the structure of the film. In conclusion, materials science has been expanded by addition of a natural, three-dimensional chitin film with utilizable properties.

Effect of Processed Beverage By-Product-Based Diets on Biological Parameters, Conversion Efficiency and Body Composition of Hermetia illucens (L) (Diptera: Stratiomyidae)

Simple Summary

The Black Soldier Fly insect (BSF) Hermetia illucens (L.) (Diptera: Stratiomyidae) metabolizes low degraded ingredients and converts them into larval enriched nutrients. In the present study, the effect of processed beverage by-products, such as spent coffee grounds and brewer’s spent grains and their mixtures on biological parameters (larval development, survival), conversion efficiency and body composition of the BSF insect was evaluated. The effect of different rearing densities of BSF on the above parameters were also studied. Insect larvae were reared successfully in all tested diets, except for sole spent coffee grounds. Substrate mass reduction, protein conversion and bioconversion rates were higher on the reference feed, followed by brewer’s spent grains and brewer’s spent grains—spent coffee grounds mixture enriched with brewer’s yeast. Density did not affect any larval parameter except for fat. Our results illustrate that low value beverage by-products can be successfully utilized as constituents of a successful BSF diet.

Abstract

The effect of spent coffee grounds (SCG), brewer’s spent grains (BSG) and their mixtures with the addition of brewer’s yeast (BY) were tested in two rearing densities of the Black Soldier Fly, Hermetia illucens (L.). Different treatments were investigated on larval development, survival, yield, protein conversion (PrCR) and bioconversion rate (BCR), substrate mass reduction and body composition of the insect. BSF larvae were able to develop sufficiently in all diets, except on sole SCG. The addition of BY enhanced the performance properties of diets, especially in the case of SCG, where larvae underperformed. Substrate mass reduction, PrCR and BCR were affected only by feed and exhibited higher values on reference feed, followed by BSG and SCG+BSG enriched with BY. Density did not have a significant effect on various larval nutrients, except for fat, which was higher on larvae fed enriched feeds with BY and in the 300 larval density. The interaction between feed and density strongly affected the nitrogen and protein levels, larval yield and ash. Generally, diets which contained SCG exhibited high larval crude protein levels. Our results illustrate that low value beverage by-products can be successfully utilized as constituents of a successful BSF diet.

Proteomic Study Reveals Major Pathways Regulating the Development of Black Soldier Fly

Nowadays, biodegrading organic waste, as a solution to confront environmental challenges, has attracted wide attention. A dipteran insect, black soldier fly (BSF), exhibits outstanding capability to convert organic waste into proteins and lipid resources, and thus, much interest has been shown in it. However, information of fundamental biology of BSF is still limited besides its recycling efficiency. In this work, we present a complete proteomic database of BSF at all instars (before prepupa). We further formulated the pathways corresponding to BSF development and built a relationship with the current genetic database. To achieve this, we investigated the proteomics of BSF during different periods. We identified 5036 proteins, and among them, 3905 proteins were annotated in the protein function database. illustrated three pathways related to major physiological processes including the insulin signaling pathway for feeding and growth, fatty acid biosynthesis pathway for fatty acid using, and toll/immune deficiency pathway for immune behavior. The proteins in these three pathways were matched with a published genetic database, and this reference library could be used for future BSF genetic engineering. In conclusion, this work provided a comprehensive protein library of BSF and expands the basic knowledge of BSF for future research.

Sustainable Superheated Water Hydrolysis of Black Soldier Fly Exuviae for Chitin Extraction and Use of the Obtained Chitosan in the Textile Field

Interest in insects as waste biomass bioconverters and their use as valuable resources for fat, proteins, and chitin has increased considerably in the last few years. In this study, proteins were extracted from defatted black soldier fly (BSF) (Hermetia illucens) exuviae by green hydrolysis using superheated water at 150 °C for 20 h, and the remaining chitin was deacetylated into chitosan and used as a finishing agent for polyester fabrics. A total amount of 7% fat, 40% proteins, and 20% chitin was obtained from BSF exuviae. Different hydrolysis times ranging from 1 to 20 h were tried until the complete purification of chitin. The purity of chitin and the obtained chitosan after deacetylation was assessed by Fourier transform infrared spectroscopy and thermal analysis. A preliminary study was successfully carried out to use the obtained chitosan as a finishing agent for polyester pretreated fabrics using citric acid as a grafting agent. The presence of chitosan on the fabric was verified by scanning electron microscopy and by dyeing of the pretreated polyester fabric using a reactive dye with sulfonated groups that are able to be absorbed by electrostatic attraction because of the created cationic nature of the fiber surface treated by chitosan.

Obtaining chitin, chitosan and their melanin complexes from insects

Interest in insects as a source of valuable biologically active substances has significantly increased over the past few years. Insects serve as an alternative source of chitin, which forms up to 40% of their exoskeleton. Chitosan, a deacetylated derivative of chitin, attracts the attention of scientists due to its unique properties (sorption, antimicrobial, film-forming, wound healing). Furthermore, some insect species are unique and can be used to obtain chitin- and chitosan-melanin complexes in the later stages of ontogenesis. Due to the synergistic effect, chitosan and melanin can enhance each other's biological activity, providing a wide range of potential applications.

Larvae Mediated Valorization of Industrial, Agriculture and Food Wastes: Biorefinery Concept through Bioconversion, Processes, Procedures, and Products

Each year, the food supply chain produces more than 1.3 billion tons of food and agricultural waste, which poses serious environmental problems. The loss of the massive quantity of secondary and primary metabolites retrievable from this resource is a significant concern. What if there is a global solution that caters to the numerous problems arising due to the humongous volume of waste biomass generated in every part of the world? Insects, the tiny creatures that thrive in decaying organic matter, which can concentrate the nutrients present in dilute quantities in a variety of by-products, are an economically viable option. The bioconversion and nutritional upcycling of waste biomass with insects yield high-value products such as protein, lipids, chitin and frass. Insect-derived proteins can replace conventional protein sources in feed formulations. Notably, the ability of the black soldier fly (BSF) or Hermetia illucens to grow on diverse substrates such as agri-food industry side streams and other organic waste proves advantageous. However, the data on industrial-scale extraction, fractionation techniques and biorefinery schemes for screening the nutritional potential of BSF are scarce. This review attempts to break down every facet of insect processing and analyze the processing methods of BSF, and the functional properties of nutrients obtained thereof.