Potential Protein and Biodiesel Sources from Black Soldier Fly Larvae: Insights of Larval Harvesting Instar and Fermented Feeding Medium

Bio-upcycling of cheese whey: Transforming waste into raw materials for biofuels and animal feed

Cheese whey (CW), by-product of cheese production, has potential as a valuable resource due to its nutritional composition. Although options for CW degradation have been explored, a biological treatment with black soldier fly larvae (BSFL) has not been reported. This study evaluated the growth and composition of BSFL in four experimental diets with CW under different conditions. Results show that the use of CW allows larval development and weight gain, also, the conversion into larval biomass was up to 0.215. Diets ED3 (fresh CW, 38 °C) and ED4 (fresh CW, room temperature) allowed higher weight accumulation (final weight up to 0.285 g); the highest fat accumulation (12 % higher than control) was observed in ED3 (up to 45.57 %), which had less protein. Moreover, higher amounts of saturated fatty acids are generated. This study highlights the importance of an appropriate pretreatment designed for a specific waste to control desired by-products.

Performance and emission characteristics of a diesel engine fuelled by biodiesel from black soldier fly larvae: Effects of synthesizing catalysts with citric acid

Biodiesel has several environmental benefits, such as biodegradability, renewability and lower soot emissions. However, biodiesel has undesirable properties such as higher viscosity and density and low calorific value compared to petroleum diesel, resulting in high Brake Specific Fuel Consumption (BSFC), reduced Brake Power (BP) and increased NOX emissions creating an environmental concerns in biodiesel development. This study investigated the effects of synthesizing transesterification catalysts (CaO and NaOH) with Citric Acid (CA) on the quality of biodiesel and biodiesel blends produced from Black Soldier Fly Larvae (BSFL) (Hermetia Illucens). The quality of biodiesel and blends was determined based on fuel properties, engine performance and emission composition characteristics. The tests were performed on a single-cylinder, four-stroke, Compression Ignition (CI) diesel engine at five loads at a constant speed of 1500 rpm. The results showed that synthesizing the catalysts with CA significantly affected the fatty acid profile of the biodiesel compared to physical fuel properties. B100 (pure BSFL biodiesel) exhibited higher BSFC by 10.57-13.97 % and lower BP by 4.21-7.83 % than diesel fuel. However, the Brake Thermal Efficiency (BTE) of biodiesel was higher than that of diesel fuel by 0.82-4.34 % at maximum load. Synthesizing catalysts with CA improved the viscosity of biodiesel by 0.93-2.81 % and effectively reduced NOX, HC and Smoke opacity by 2.23-3.16 %, 4.95-5.83 % and 20.51-41.15 %, respectively.

Revealing the effects of fermented food waste on the growth and intestinal microorganisms of black soldier fly (Hermetia illucens) larvae

The escalating global food waste (FW) issues necessitate sustainable management strategies. Black soldier fly larvae (BSFL) offer a promising solution for FW management by converting organic matter into insect protein. However, the fermentation of FW during production, collection, and transportation induces changes in FW's physicochemical properties and bacterial communities, requiring further exploration of its impact on BSFL growth and gut microbiota. The results showed that feeding FW fermented for different durations (0-10 d) slightly affected the BSFL yield. Feeding FW fermented for 8 d, characterized by a lower pH and higher biodiversity, resulted in a slight increase in larval biomass (222 mg/larvae). Nearly all groups harvested the peak larval biomass after 10 day's bioconversion. The fermentation significantly altered the microbial community of FW, with an increase in the abundance of unclassified_f_Clostridiaceae and a decrease in Lactobacillus abundance. As bioconversion progressed, intricate and mutualistic microbial interactions likely occurred between the BSFL gut and FW substrate, restructuring each other's microbial community. Specifically, the abundance of unclassified_f_Clostridiaceae increased in the BSFL gut, while its abundance in the initial larval gut was extremely low (<1 %). Despite the substrate microbial changes and interactions, a stable core gut microbiota was identified across all BSFL samples, primarily composed of nine genera dominated by Enterococcus and Klebsiella. This core gut microbiome may play a crucial role in facilitating the adaptation of BSFL to various environmental conditions and maintaining efficient FW bioconversion. These findings enhance our understanding of the role of BSFL gut microbiota in FW bioconversion.

Life cycle assessment: Sustainability of biodiesel production from black soldier fly larvae feeding on thermally pre-treated sewage sludge under a tropical country setting

More energy is needed nowadays due to global population growth. Concurrently, sewage sludge generation has also increased steadily stemming from the inevitable urbanization. As such, black soldier fly larvae (BSFL) can be potentially deployed to solve both issues. This paper investigates the environmental sustainability of biodiesel production derived from sludge-fed BSFL feedstock. A cradle-to-gate life cycle assessment (LCA) was performed through SimaPro software utilizing the ReCiPe 2016 Midpoint (H) and Endpoint (H) methods. The entire LCA covered 3 main stages, including the thermal pre-treatment of sludge, BSFL rearing and processing, and lastly lipid extraction and biodiesel production. LCA showed that the sludge pre-treatment stage had the highest environmental impact, while BSFL rearing and processing had the least due to the suitable geographical climate. Electricity usage during the pre-treatment stage was the main contributing component, followed by chemical usage during biodiesel production. After normalizing, it was observed that land occupation, marine ecotoxicity, freshwater ecotoxicity and freshwater eutrophication were more impactful than the commonly studied global warming potential (GWP). Lipid content and biodiesel conversion efficiency were determined as the sensitive factors which could influence the LCA outcome. In comparison with other types of biodiesel, BSFL biodiesel had a milder impact in terms of climate change, land occupation, terrestrial acidification, marine and freshwater eutrophication. Furthermore, this biological reduction of sludge through BSFL valorization avoided sludge landfilling, which reduced up to 100 times GWP. Therefore, sludge-fed BSFL biodiesel production is an environmentally-sound and highly potential solution that should be investigated comprehensively.

Insect biorefinery: A circular economy concept for biowaste conversion to value-added products

With rapid growing world population and increasing demand for natural resources, the production of sufficient food, feed for protein and fat sources and sustainable energy presents a food insecurity challenge globally. Insect biorefinery is a concept of using insect as a tool to convert biomass waste into energy and other beneficial products with concomitant remediation of the organic components. The exploitation of insects and its bioproducts have becoming more popular in recent years. This review article presents a summary of the current trend of insect-based industry and the potential organic wastes for insect bioconversion and biorefinery. Numerous biotechnological products obtained from insect biorefinery such as biofertilizer, animal feeds, edible foods, biopolymer, bioenzymes and biodiesel are discussed in the subsequent sections. Insect biorefinery serves as a promising sustainable approach for waste management while producing valuable bioproducts feasible to achieve circular bioeconomy.

Black soldier fly (Hermetia illucens) larvae as potential feedstock for the biodiesel production: Recent advances and challenges

Black soldier fly larvae (BSFL) Hermetia illucens is fastest growing and most promising insect species especially recommended to bring high-fat content as 5th generation bioenergy. The fat content can be fully optimized during the life-cycle of the BSFL through various organic dietary supplements and environmental conditions. Enriched fat can be obtained during the larval stages of the BSF. The presence of high saturated and unsaturated fatty acids in their body helps to produce 70 % of extractable oil which can be converted into biodiesel through transesterification. The first-generation biodiesel process mainly depends on catalytic transesterification, however, BSFL had 94 % of biodiesel production through non-catalytic transesterification. This increases the sustainability of producing biodiesel with less energy input in the process line. Other carbon emitting factors involved in the rearing of BSFL are less than the other biodiesel feedstocks including microalgae, cooking oil, and non-edible oil. Therefore, this review is focused on evaluating the optimum dietary source to produce fatty acid rich larvae and larval growth to accumulate C16-18 fatty acids in larger amounts from agro food waste. The process of optimization and biorefining of lipids using novel techniques have been discussed herein. The sustainability impact was evaluated from the cultivation to biodiesel conversion with greenhouse gas emissions scores in the entire life-cycle of process flow. The state-of-the-art in connecting circular bioeconomy loop in the search for bioenergy was meticulously covered.

Effects of salvaged cyanobacteria content on larval development and feedstock humification during black soldier fly larvae (Hermetia illucens) composting

Cyanobacteria salvage is widely used to deal with massive cyanobacterial blooms. Improper disposal of salvaged cyanobacteria would cause secondary pollution. Black soldier fly (Hermetia illucens) larvae (BSFL) can bio-convert organic wastes into larval biomass, which is rich in protein and lipid. This study evaluated the possibility of using BSFL composting for salvaged cyanobacteria treatment. Results showed that increasing salvaged cyanobacteria waste (CW) content (from 0 to 50%, dry weight basis) extended BSFL development time, e.g., BSFL fed with 50% CW needed 14 days more to finish development than Control (0% CW). The CW content (0-20%) in feeding substrates had no significant effect on BSFL body length and weight. Whereas further increase of CW content (from 20 to 50%) led to significant reductions in substrate-to-BSFL biomass conversion ratio, body size, body weight, and crude protein content of BSFL. Meanwhile, the presence of salvaged cyanobacteria in the feeding substrate reduced the degradation efficiency of feeding substrate. The dissolved organic matter (DOM) results demonstrated that the increased salvaged cyanobacteria content made it more difficult for BSFL to degrade the feeding substrate into simple organic matter and further into humic-like substances. Furthermore, salvaged cyanobacteria in feeding substrates affected the intestinal microbial community significantly. With 20% CW content in the feeding substrate, the relative abundance of Firmicutes decreased from 92.43 to 81.24%, while the relative abundance of Proteobacteria and Bacteroidetes increased from 4.10 to 2.93-8.75% and 7.51%, respectively. BSFL composting is feasible to convert salvaged cyanobacteria into insect biomass. However, the salvaged cyanobacteria content in the feeding substrate should be carefully controlled (e.g., less than 30%).

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.

Food waste and soybean curd residue composting by black soldier fly

This study attempted to manage the food waste and soybean curd residue generated in Taiwan's National Ilan University by black soldier fly-aided co-composting. The food waste and soybean curd residue were co-composted with rice husk as a bulking agent in 4:1 ratio and 0.42 mg BSF/g waste. The higher organic matter degradation of 31.9% was found in Container B (black soldier flies aided food waste and rice husk co-composting) with a rate constant of 0.14 d-1. In Container D (black soldier flies aided soybean curd residue and rice husk co-composting), the organic matter degradation of 29.4% was found with a rate constant of 0.29 d-1. The matured compost of 6.02 kg was obtained from 20 kg of food waste, while 5.83 kg of matured compost was generated from 20 kg of soybean curd residue. The physico-chemical parameters of the final matured compost were in the favorable range of Taiwan's compost standards. The germination index was 188.6% and 194.78% in Containers B and D, respectively. The present study will expand the application of BSF at the institutional level which prove to be a feasible solution for rapid, clean, and efficient composting of post-consumer food wastes.

Fungal Fermented Palm Kernel Expeller as Feed for Black Soldier Fly Larvae in Producing Protein and Biodiesel

Being the second-largest country in the production of palm oil, Malaysia has a massive amount of palm kernel expeller (PKE) leftover. For that purpose, black soldier fly larvae (BSFL) are thus employed in this study to valorize the PKE waste. More specifically, this work elucidated the effects of the pre-fermentation of PKE via different amounts of Rhizopus oligosporus to enhance PKE palatability for the feeding of BSFL. The results showed that fermentation successfully enriched the raw PKE and thus contributed to the better growth of BSFL. BSFL grew to be 34% heavier at the optimum inoculum volume of 0.5 mL/10 g dry weight of PKE as compared to the control. Meanwhile, excessive fungal inoculum induced competition between BSFL and R. oligosporus, resulting in a reduction in BSFL weight. Under optimum feeding conditions, BSFL also registered the highest lipid yield (24.7%) and protein yield (44.5%). The biodiesel derived from BSFL lipid had also shown good compliance with the European biodiesel standard EN 14214. The high saturated fatty acid methyl esters (FAMEs) content (C12:0, C14:0, C16:0) in derived biodiesel made it highly oxidatively stable. Lastly, the superior degradation rate of PKE executed by BSFL further underpinned the sustainable conversion process in attaining valuable larval bioproducts.

Evaluation of Antibacterial and Antifungal Properties of Low Molecular Weight Chitosan Extracted from Hermetia illucens Relative to Crab Chitosan

This study shows the research on the depolymerisation of insect and crab chitosans using novel enzymes. Enzyme preparations containing recombinant chitinase Chi 418 from Trichoderma harzianum, chitinase Chi 403, and chitosanase Chi 402 from Myceliophthora thermophila, all belonging to the family GH18 of glycosyl hydrolases, were used to depolymerise a biopolymer, resulting in a range of chitosans with average molecular weights (Mw) of 6-21 kDa. The depolymerised chitosans obtained from crustaceans and insects were studied, and their antibacterial and antifungal properties were evaluated. The results proved the significance of the chitosan's origin, showing the potential of Hermetia illucens as a new source of low molecular weight chitosan with an improved biological activity.

Black soldier fly larvae for treatment and segregation of commingled municipal solid waste at different environmental conditions

The commingled nature of the municipal solid waste in many developing nations is one of the primary reasons behind the failure to its successful management. Although there are technologies to effectively treat and process well-segregated and classified waste, they are ineffective in managing the commingled waste. Commingled waste has neither calorific value enough to support waste-to-energy operations nor is it suitable for producing quality compost to generate market value. In this article, a novel Black Soldier Fly Larva (BSFL) -based technology has been proposed and tested to auto-segregate and treat the biodegradable fraction of the Commingled Municipal Solid Waste (CMSW). Several BSFL feeding experiments on five different CMSW compositions were conducted at various temperatures and relative humidity conditions. BSFL could selectively consume the biodegradable fraction of the CMSW to convert it into its body mass and separate itself from the rest of the waste, which mainly consisted of inert and recyclable waste fractions that can be further treated using appropriate waste treatment technology. The mature larvae or the pre-pupae grown at the expense of the biodegradable waste fraction can find several commercial uses. The larvae's consumption rate and weight gain were dependent on the environmental conditions; 30 °C and relative humidity of 65-75% provided the highest consumption rate and most significant weight gain. The batch experiments in the laboratory proved that BSFL could be promising for the treatment of CMSW. The experimental data presented may help design a process for further scaling up an effective treatment method for CMSW, which might benefit many developing nations in managing their waste effectively and economically.

Understanding dietary carbohydrates in black soldier fly larvae treatment of organic waste in the circular economy

Black soldier fly larvae (BSFL) treatment is promising for organic waste valorisation in the circular economy; however, waste variability impacts the process performance and quality of produced larvae. Specifically, variation in the carbohydrate profile of treated wastes has been suggested to have a significant impact on BSFL treatment performance and quality of produced larvae, with particular carbohydrates either positively or negatively influencing these variables. This study examines the hypothesis that the types of carbohydrates within the substrate can have significant influence on larval survival, waste reduction, bioconversion, and waste conversion efficiency, as well as the crude lipid content and fatty acid profiles of the produced larvae. The carbohydrates explored were D glucose, sucrose, D (-) fructose, corn and wheat starch, D (+) galactose, D (+) mannose, D (+) xylose, D (-) arabinose and xylan from beechwood. Young larvae were grown for 9 days on chicken feed-based diets containing various carbohydrate additives each at 20 dry mass %. Treatments containing hemicellulose constituents galactose and arabinose produced the most adverse effects on process performance relative to the benchmark. Xylan was significantly detrimental to bioconversion (-14.7 ± 3.8%) and waste conversion efficiencies (-19.0 ± 4.4%). There were minimal significant effects on performance from mono- and di-saccharides and starch additives. Larvae crude lipid contents were significantly increased by wheat starch (+12.6 ± 3.0%) and decreased by galactose (-15.0 ± 1.4%) and xylan additives (-27.5 ± 3.4%), however fatty acid profiles were largely unaffected and were dominated by lauric acid. These results indicate that despite an otherwise balanced and nutritious substrate, the carbohydrate profile of organic waste should be an important consideration in BSFL treatment when ensuring process performance and larval lipid contents. The consequences of these results for BSFL treatment of real wastes are discussed. Large scale treatment facilities should formulate substrates accordingly and identify methods to mitigate the anti-nutritional effects of poor carbohydrate profiles, particularly those high in hemicelluloses and their constituents.

The Nutritional Profiles of Five Important Edible Insect Species From West Africa-An Analytical and Literature Synthesis

Background: Undernutrition is a prevalent, serious, and growing concern, particularly in developing countries. Entomophagy—the human consumption of edible insects, is a historical and culturally established practice in many regions. Increasing consumption of nutritious insect meal is a possible combative strategy and can promote sustainable food security. However, the nutritional literature frequently lacks consensus, with interspecific differences in the nutrient content of edible insects generally being poorly resolved.

Aims and methods: Here we present full proximate and fatty acid profiles for five edible insect species of socio-economic importance in West Africa: Hermetia illucens (black soldier fly), Musca domestica (house fly), Rhynchophorus phoenicis (African palm weevil), Cirina butyrospermi (shea tree caterpillar), and Macrotermes bellicosus (African termite). These original profiles, which can be used in future research, are combined with literature-derived proximate, fatty acid, and amino acid profiles to analyse interspecific differences in nutrient content.

Results: Interspecific differences in ash (minerals), crude protein, and crude fat contents were substantial. Highest ash content was found in H. illucens and M. domestica (~10 and 7.5% of dry matter, respectively), highest crude protein was found in C. butyrospermi and M. domestica (~60% of dry matter), whilst highest crude fat was found in R. phoenicis (~55% of dry matter). The fatty acid profile of H. illucens was differentiated from the other four species, forming its own cluster in a principal component analysis characterized by high saturated fatty acid content. Cirina butyrospermi had by far the highest poly-unsaturated fatty acid content at around 35% of its total fatty acids, with α-linolenic acid particularly represented. Amino acid analyses revealed that all five species sufficiently met human essential amino acid requirements, although C. butyrospermi was slightly limited in leucine and methionine content.

Discussion: The nutritional profiles of these five edible insect species compare favorably to beef and can meet human requirements, promoting entomophagy's utility in combatting undernutrition. In particular, C. butyrospermi may provide a source of essential poly-unsaturated fatty acids, bringing many health benefits. This, along with its high protein content, indicates that this species is worthy of more attention in the nutritional literature, which has thus-far been lacking.

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.

On the nitrogen content and a robust nitrogen-to-protein conversion factor of black soldier fly larvae (Hermetia illucens)

Currently, a broad discussion exists in the literature regarding insect protein analysis. At its core, main difficulties and uncertainties are the inconsistent use of analysis methods and nitrogen-to-protein conversion (k_P) factors. While the Kjeldahl and Dumas methods are both used in the literature, their result represents inherently different nitrogen fractions. Thus far, no correlation between them is established for insect matrices, which is a major uncertainty. Although much effort has been made towards more accurate k_P factors, calculation of these was based on merely one sample while the chemical composition varies depending on rearing conditions. Using a broad variation in black soldier fly (BSF) larvae samples in the present study, a correlation between Kjeldahl and Dumas and a robust k_P factor have been established. Moreover, the nitrogen distribution of BSF samples was also assessed after accurate chitin analyses. A highly significant linear correlation existed between the results of Kjeldahl and Dumas (slope, 1.009; intercept, - 0.008; R², 0.9997). Consequently, both methods were deemed interchangeable for BSF larvae. Using amino acid data, a practical, more accurate and robust k_P factor of 4.43 was obtained. Concerning the chitin content, the average of all BSF larvae samples was 5.95 ± 0.86 g N-acetylglucosamine/100 g dry matter and no correlation with the k_P factor was observed. Regarding the nitrogen distribution of the samples, it was found that the contribution of nitrogenous compounds other than protein and chitin is not only high but also prone to variation (12-30% of the total nitrogen content).

Electricity Markets during the Liberalization: The Case of a European Union Country

This paper analyzes electricity markets in Slovenia during the specific period of market deregulation and price liberalization. The drivers of electricity prices and electricity consumption are investigated. The Slovenian electricity markets are analyzed in relation with the European Energy Exchange (EEX) market. Associations between electricity prices on the one hand, and primary energy prices, variation in air temperature, daily maximum electricity power, and cross-border grid prices on the other hand, are analyzed separately for industrial and household consumers. Monthly data are used in a regression analysis during the period of Slovenia’s electricity market deregulation and price liberalization. Empirical results show that electricity prices achieved in the EEX market were significantly associated with primary energy prices. In Slovenia, the prices for daily maximum electricity power were significantly associated with electricity prices achieved on the EEX market. The increases in electricity prices for households, however, cannot be explained with developments in electricity prices on the EEX market. As the period analyzed is the stage of market deregulation and price liberalization, this can have important policy implications for the countries that still have regulated and monopolized electricity markets. Opening the electricity markets is expected to increase competition and reduce pressures for electricity price increases. However, the experiences and lessons learned among the countries following market deregulation and price liberalization are mixed. For industry, electricity prices affect cost competitiveness, while for households, electricity prices, through expenses, affect their welfare. A competitive and efficient electricity market should balance between suppliers’ and consumers’ market interests. With greening the energy markets and the development of the CO2 emission trading market, it is also important to encourage use of renewable energy sources.

The Influence of Food Waste Rearing Substrates on Black Soldier Fly Larvae Protein Composition: A Systematic Review

Simple Summary

The Black Soldier Fly (BSF) is a viable option for countering the environment detriments caused by food waste and can provide a sustainable protein source to feed the growing global population. This systematic literature review investigated the impacts of various foodstuffs and food waste rearing substrates on the protein and amino acid composition of BSF larvae. From the 23 articles included, BSF larvae fed ‘Fish waste Sardinella aurita’ for two days produced the highest total protein content at 78.8% and rearing substrates ‘Fruit and vegetables’ reported the lowest protein content at 12.9% of the BSF total mass. However, variation in rearing and analytical methodologies between each study potential undermines the extent to which the rearing substrates may have influenced the overall protein content of BSF larvae, their application in nutrition is still in its infancy.

Abstract

The Black Soldier Fly (BSF) offers the potential to address two global challenges; the environmental detriments of food waste and the rising demand for protein. Food waste digested by BSF larvae can be converted into biomass, which may then be utilized for the development of value-added products including new food sources for human and animal consumption. A systematic literature search was conducted to identify studies investigating the influence of food waste rearing substrates on BSF larvae protein composition. Of 1712 articles identified, 23 articles were selected for inclusion. Based on the results of this review, BSF larvae reared on ‘Fish waste Sardinella aurita’ for two days reported the highest total protein content at 78.8% and BSF larvae reared on various formulations of ‘Fruit and vegetable’ reported the lowest protein content at 12.9%. This review is the first to examine the influence of food waste on the protein composition of BSF larvae. Major differences in larval rearing conditions and methods utilized to perform nutritional analyses, potentially influenced the reported protein composition of the BSF larvae. While this review has highlighted the role BSF larvae in food waste management and alternative protein development, their application in nutrition is still in its infancy.

Sustainable management of Se-rich silkworm residuals by black soldier flies larvae to produce a high nutritional value and accumulate ω-3 PUFA

Waste disposal and utilisation of its important components are pioneering goals for achieving sustainable development and a clean environment. Silkworm pupae (SWP) are considered a by-product of the sericulture industry and may contain a high concentration of selenium (Se) in some regions, making them a potentially hazardous waste posing health risks. This study examined six treatments of Se-rich SWP (0-100%) as a substrate for black soldier fly (BSF) larvae. Growth performance and protein content of BSF larvae were not affected by increasing SWP content. The total fat, mono-, and poly-unsaturated fatty acids in BSF pre-pupae increased with increasing SWP inclusion in the substrate, from P0 (pre-pupae fed control treatment) through P100 (pre-pupae fed 100% SWP treatment), by 18.83, 61.14, and 62.42%, respectively. The results of significance were: (1) BSF pre-pupae did not accumulate Se, maintaining the same amount of Se in their bodies (~0.18 mg/kg); (2) omega-3 fatty acids represented by linolenic acid in BSF increased by 1,223.35% from P0 to P100, with 70.65% recovered from the SWP; (3) valine percentage increased in BSF compared with the percentage of SWP by 25.30%; and (4) BSF larvae were observed reducing SWP waste by more than one-third. BSF larvae can reduce the waste from sericulture industry and exploit the beneficial properties and components of SWP, converting them into safe and highly nutritious products.

Rhizopus oligosporus-Assisted Valorization of Coconut Endosperm Waste by Black Soldier Fly Larvae for Simultaneous Protein and Lipid to Biodiesel Production

Coconut endosperm waste (CEW) was treated by Rhizopus oligosporus via in situ and ex situ fermentations together with bioconversion into valuable black soldier fly larval biomass. The ex situ fermentation could overall enrich the nutritional compositions of CEW by hydrolyzing its complex organic polymers and exuding assimilable nutrients to enhance the black soldier fly larvae (BSFL) growth. Nevertheless, the larval gut bacteria were competing with Rhizopus oligosporus in in situ fermentation, derailing the hydrolysis processes and larval growth. Accordingly, the highest growth rates achieved were around 0.095 g/day, as opposed to only 0.065 g/day whilst using 0.5 wt% of Rhizopus oligosporus to perform ex situ and in situ fermentations, respectively. These were also underpinned by the greater amount of total CEW consumed when employing ex situ fermentation, with comparable metabolic costs to feeding on in situ-fermented CEW. The mature BSFL were subsequently harvested and the amounts of protein and lipid produced were assessed in terms of their feasibility for biodiesel production. While the statistical analyses showed that the larval protein yields derived from both fermentation modes were insignificant, the BSFL could attain higher lipid and protein productivities upon feeding with ex situ- rather than in situ-fermented CEW mediums. Better yet, the larval biodiesel quality measured in terms of the fatty acid methyl ester composition were not varied significantly by Rhizopus oligosporus through the fermentation process. Thereby, the presence of 1.0 wt% Rhizopus oligosporus was considered optimum to perform ex situ fermentation, giving rise to the acceptable growth of BSFL loaded with the highest lipid yield and productivity for producing biodiesel and protein simultaneously.

Impact of Processed Food (Canteen and Oil Wastes) on the Development of Black Soldier Fly (Hermetia illucens) Larvae and Their Gut Microbiome Functions

Canteens represent an essential food supply hub for educational institutions, companies, and business parks. Many people in these locations rely on a guaranteed service with consistent quality. It is an ongoing challenge to satisfy the demand for sufficient serving numbers, portion sizes, and menu variations to cover food intolerances and different palates of customers. However, overestimating this demand or fluctuating quality of dishes leads to an inevitable loss of unconsumed food due to leftovers. In this study, the food waste fraction of canteen leftovers was identified as an optimal diet for black soldier fly (Hermetia illucens) larvae based on 50% higher consumption and 15% higher waste reduction indices compared with control chicken feed diet. Although the digestibility of food waste was nearly twice as high, the conversion efficiency of ingested and digested chicken feed remains unparalleled (17.9 ± 0.6 and 37.5 ± 0.9 in CFD and 7.9 ± 0.9 and 9.6 ± 1.0 in FWD, respectively). The oil separator waste fraction, however, inhibited biomass gain by at least 85% and ultimately led to a larval mortality of up to 96%. In addition to monitoring larval development, we characterized physicochemical properties of pre- and post-process food waste substrates. High-throughput amplicon sequencing identified Firmicutes, Proteobacteria, and Bacteroidota as the most abundant phyla, and Morganella, Acinetobacter, and certain Lactobacillales species were identified as indicator species. By using metagenome imputation, we additionally gained insights into the functional spectrum of gut microbial communities. We anticipate that the results will contribute to the development of decentralized waste-management sites that make use of larvae to process food waste as it has become common practice for biogas plants.

Material flow analysis and life cycle assessment of food waste bioconversion by black soldier fly larvae (Hermetia illucens L.)

This study provided a systematic analysis on material flow and environmental impacts of a food waste (FW) bioconversion plant using black soldier fly larvae (BSFL), with a daily capacity of 15 tons of FW (wet weight). Food waste feed (FWF) used for BSFL bioconversion consisted of 80% FW (collected from households, restaurants, and canteens) and 20% rice hull powder. Material flow analysis conducted on a dry weight basis showed that 6% of FWF was transformed into BSF pre-pupae, 51% was stored in matured compost, and 43% was emitted to the air. Emissions of high environmental concern such as methane, nitrous oxide and ammonia (NH₃) were sampled and quantified by laboratory analysis. The life cycle assessment revealed that the overall impact was 17.36 kg CO₂-eq/t FW for global warming potential, 5.54 kg SO₂-eq/t FW for acidification, 24.05 mol N-eq/t FW for terrestrial eutrophication, 0.54 kg N-eq NH₃/t FW for marine eutrophication, and 0.18 kg PM_2.5-eq/t FW of particulate matter up to 2.5 μm diameter. Moreover, emissions from post-composting, energy consumptions of drying and chemical fertilizer substitution ratio were detected by contribution analysis as the main contributors to those impacts. Finally, sensitivity analysis indicated that the substitution ratio of mineral fertilizer and protein feed as well as energy consumption were the most influential parameters, therefore control of the post-composting process of residual material should be closely monitored because it was responsible for significant environmental load caused by N-related emissions.

A review of organic waste enrichment for inducing palatability of black soldier fly larvae: Wastes to valuable resources

The increase of annual organic wastes generated worldwide has become a major problem for many countries since the mismanagement could bring about negative effects on the environment besides, being costly for an innocuous disposal. Recently, insect larvae have been investigated to valorize organic wastes. This entomoremediation approach is rising from the ability of the insect larvae to convert organic wastes into its biomass via assimilation process as catapulted by the natural demand to complete its lifecycle. Among the insect species, black soldier fly or Hermetia illucens is widely researched since the larvae can grow in various environments while being saprophagous in nature. Even though black soldier fly larvae (BSFL) can ingest various decay materials, some organic wastes such as sewage sludge or lignocellulosic wastes such as waste coconut endosperm are destitute of decent nutrients that could retard the BSFL growth. Hence, blending with nutrient-rich low-cost substrates such as palm kernel expeller, soybean curd residue, etc. is employed to fortify the nutritional contents of larval feeding substrates prior to administering to the BSFL. Alternatively, microbial fermentation can be adopted to breakdown the lignocellulosic wastes, exuding essential nutrients for growing BSFL. Upon reaching maturity, the BSFL can be harvested to serve as the protein and lipid feedstock. The larval protein can be made into insect meal for farmed animals, whilst the lipid source could be extracted and transesterified into larval biodiesel to cushion the global energy demands. Henceforth, this review presents the influence of various organic wastes introduced to feed BSFL, targeting to reduce wastes and producing biochemicals from mature larvae through entomoremediation. Modification of recalcitrant organic wastes via fermentation processes is also unveiled to ameliorate the BSFL growth. Lastly, the sustainable applications of harvested BSFL biomass are as well covered together with the immediate shortcomings that entail further researches.

Liminal presence of exo-microbes inoculating coconut endosperm waste to enhance black soldier fly larval protein and lipid

The anaerobic decomposition of coconut endosperm waste (CEW), residue derived from cooking, has been insidiously spewing greenhouse gasses. Thus, the bioconversion of CEW via in situ fermentation by exo-microbes from commercial Rid-X and subsequent valorization by black soldier fly larvae (BSFL) was the primary objective of the current study to gain sustainable larval lipid and protein. Accordingly, various concentrations of exo-microbes were separately homogenized with CEW to perform fermentation amidst feeding to BSFL. It was found that 2.50% of exo-microbes was the threshold amount entailed to assuage competition between exo-microbes and BSFL for common nutrients. The presence of remnant nutrients exuded from the fermentation using 2.50% of exo-microbes was confirmed to promote BSFL growth measured as maximum larval weight gained and growth rate. Although the BSFL could accumulate the highest protein (16 mg/larva) upon feeding with CEW containing 2.50% of exo-microbes, more lipid (13 mg/larva) was stored in employing 0.10% of exo-microbes because of minimum loss to metabolic processes while prolonging the BSFL in its 5th instar stage.

Valorization of exo-microbial fermented coconut endosperm waste by black soldier fly larvae for simultaneous biodiesel and protein productions

The conventional practice in enhancing the larvae growths is by co-digesting the low-cost organic wastes with palatable feeds for black soldier fly larvae (BSFL). In circumventing the co-digestion practice, this study focused the employment of exo-microbes in a form of bacterial consortium powder to modify coconut endosperm waste (CEW) via fermentation process in enhancing the palatability of BSFL to accumulate more larval lipid and protein. Accordingly, the optimum fermentation condition was attained by inoculating 0.5 wt% of bacterial consortium powder into CEW for 14-21 days. The peaks of BSFL biomass gained and growth rate were initially attained whilst feeding the BSFL with optimum fermented CEW. These were primarily attributed by the lowest energy loss via metabolic cost, i.e., as high as 22% of ingested optimum fermented CEW was effectively bioconverted into BSFL biomass. The harvested BSFL biomass was then found containing about 40 wt% of lipid, yielding 98% of fatty acid methyl esters of biodiesel upon transesterification. Subsequently, the protein content was also analyzed to be 0.32 mg, measured from 20 harvested BSFL with a corrected-chitin of approximately 8%. Moreover, the waste reduction index which represents the BSFL valorization potentiality was recorded at 0.31 g/day 20 BSFL. The benefit of fermenting CEW was lastly unveiled, accentuating the presence of surplus acid-producing bacteria. Thus, it was propounded the carbohydrates in CEW were rapidly hydrolysed during fermentation, releasing substantial organic acids and other nutrients to incite the BSFL assimilation into lipid for biodiesel and protein productions simultaneously.

A Review on Insights for Green Production of Unconventional Protein and Energy Sources Derived from the Larval Biomass of Black Soldier Fly

The purpose of this review is to reveal the lipid and protein contents in black soldier fly larvae (BSFL) for the sustainable production of protein and energy sources. It has been observed from studies in the literature that the larval lipid and protein contents vary with the rearing conditions as well as the downstream processing employed. The homogenous, heterogenous and microbial-treated substrates via fermentation are used to rear BSFL and are compared in this review for the simultaneous production of larval protein and biodiesel. Moreover, the best moisture content and the aeration rate of larval feeding substrates are also reported in this review to enhance the growth of BSFL. As the downstream process after harvesting starts with larval inactivation, various related methods have also been reviewed in relation to its impact on the quality/quantity of larval protein and lipids. Subsequently, the other downstream processes, namely, extraction and transesterification to biodiesel, are finally epitomized from the literature to provide a comprehensive review for the production of unconventional protein and lipid sources from BSFL feedstock. Incontrovertibly, the review accentuates the great potential use of BSFL biomass as a green source of protein and lipids for energy production in the form of biodiesel. The traditional protein and energy sources, preponderantly fishmeal, are unsustainable naturally, pressingly calling for immediate substitutions to cater for the rising demands. Accordingly, this review stresses the benefits of using BSFL biomass in detailing its production from upstream all the way to downstream processes which are green and economical at the same time.

In-Situ Yeast Fermentation to Enhance Bioconversion of Coconut Endosperm Waste into Larval Biomass of Hermetia illucens: Statistical Augmentation of Larval Lipid Content

The aim of this study was to spur the lipid accumulation by larvae of Hermetia illucens or black soldier fly (BSFL) via feeding with yeast fermented medium. The Saccharomyces cerevisiae, a single cell yeast, was introduced at different concentrations (0.02, 0.1, 0.5, 1.0, 2.5 wt %) to execute an in-situ fermentation on coconut endosperm waste. The rearing of BSFL was started simultaneously and the rearing was stopped once the BSFL reached the fifth instar. With the increasing of yeast concentration, the rearing duration of BSFL was shortened from 15.5 to 13.5 days. Moreover, it was found that at 0.5 to 1.0 wt % yeast concentration, the lipid yield and lipid productivity of BSFL were statistically enhanced to their highest peaks, namely, at 49.4% and 0.53 g/day, respectively. With regard to biodiesel composition, BSFL-derived biodiesel contained mainly C12:0, C14:0, C16:0 and C18:1. The higher amount of saturated fatty acids could strengthen the oxidative stability biodiesel produced as compared with non-edible oils or microalgal lipid. At last, the addition of yeast was also found to improve the waste reduction index of coconut endosperm waste (CEW) from 0.31 to 0.40 g/day, heralding the capability of BSFL to valorize organic waste via bioconversion into its biomass to serve as a feedstock for biodiesel production.