Insects are recognized as a highly promising protein source for the future, particularly due to their high nutritional value, efficiency and potential to alleviate food insecurity [1
]. Additionally, insect production offers a more sustainable alternative with a smaller ecological footprint compared to traditional livestock farming practices involving vertebrates like cattle and swine, which are related to surface and groundwater contamination by nutrients, toxins and pathogens as well as the significant release of substantial amounts of ammonia, among other environmental problems [2
]. In fact, insect farming is awakening interest (mostly due to sustainability issues) in recent years in markets that have not been traditional consumers of these kinds of products, like European and Northern American countries. Hence, the demand for insect-based products is on the rise, leading to increased production and trade volumes [4
]. According to the International Platform of Insects for Food and Feed, insect food business operators produced about 500 tonnes of insect-based products in 2019 and are expected to produce about 260,000 tonnes by 2023.
Some of the most common insects that are being farmed for food and feed purposes include crickets like Acheta domesticus
, mealworms like Tenebrio molitor
and flies like Musca domestica
and Hermetia Illucens
(black soldier fly, BSF). In particular, the BSF has several major advantages over other insect species. For instance, BSF larvae can break down different types of organic material like fruits, vegetables and animal manure [5
]. Their use for the latter organic material is pretty interesting since, as mentioned by Erickson et al. [8
], BSF larvae inactivate pathogen bacteria like Escherichia coli
O157:H7 and Salmonella
species, which are present in animal manure.
Currently, the production of insects at an industrial scale is carried out by a reduced number of companies, with their main target group being pets and livestock feed [2
]. Hence, the information about insect processing methods is scarce and usually only available at a laboratory scale [10
]. Satisfying the quality standards related to insect protein digestibility for animal feed holds utmost importance. However, an even more crucial factor is to ensure food safety [11
]. The first step in obtaining edible insect products is to harvest and separate them from the residues, followed by their killing and washing [12
]. In the case of larvae/worms, they are usually separated by sieving and sacrificed by blanching to reduce the microbial population, with the food spoilage and poisoning degradative enzymes being inactivated as well [13
The aim of drying processing technologies is to reduce the total water content. This limits the degradative reactions, which at the same time increases the shelf-life of foods [14
]. Some examples of the drying techniques used are roasting and sun-drying (traditional processes) or more recent ones like freeze-drying and drying assisted by microwaves. In particular, to obtain edible insect meal and powder, some of the most used techniques are drying by the sun, oven or freezing [15
One of the key processes in obtaining protein-enriched ingredients from edible insects is the defatting step due to the high fat content of insects [17
]. Moreover, insects that have undergone defatting exhibit elevated nutritional value and enhanced functionality compared to raw insect protein [18
]. One of the mostly widely used extraction processes of lipids in the food industry is performed using hexane due to its high oil recovery ability [19
]. However, the use of hexane is not currently considered a good option as it presents some constraints in health, safety, environmental and economic terms; thus, other options were recently investigated for its substitution [20
]. Some examples of alternative methods are aqueous extraction, three-phase partitioning and supercritical fluid extraction (SFE) with CO2
and mechanical pressing [21
]. In the case of mechanical pressing (dry processing), this step is performed using a screw press at an industrial scale. Moreover, additional heating improves the defatting process by mechanical pressing [22
]. With regard to alternative defatting techniques, defatting by means of SFE with CO2
showed promising results (95% oil recovery from Tenebrio molitor
). However, this treatment method shows high operating costs at an industrial scale [23
]. Therefore, SFE using CO2
could become in a real alternative technique when it is optimized and, thus, the costs are reduced.
It is worth mentioning that the current studies on insect larvae processing are primarily focused on individual evaluations of the three previously described processes—sacrifice, drying and defatting—without consideration for their collective application towards the final product of insect meal [24
]. While several studies examined the different methods of sacrifice, drying or defatting, there remains a gap in research that explores the interconnectedness of these three technological processes as successive operations within a single, cohesive production process. Exploring the collective application of sacrifice, drying and defatting processes as successive operations in the production process of insect proteins is important for several reasons: product quality and safety, efficiency and cost effectiveness, nutritional value optimization, sustainability, etc. [1
In short, there are diverse challenges to insect processing to be addressed, such as (i) the development of efficient technologies, (ii) the promotion of environmentally friendly practices and (iii) the establishment of cost competitiveness. Although several authors evaluated the environmental impact of insect production, most of these studies’ final product focus was whole larvae/worms with few processing steps included [26
]. Considering that farming and processing of insect proteins contribute the most to the overall environmental impact and may not always be favorable when compared to traditional protein feeds [31
], obtaining a true environmental assessment from insect production systems is of vital importance for the further expansion and up-scaling of the insect industry. Thus, the present study aims to analyze the environmental impacts associated with insect protein production including all processing steps (sacrifice, drying and defatting) and covering different available technologies (blanching, freezing, oven drying, lyophilization, hot pressing and SFE with CO2
). These technologies are combined in order to study the interconnectedness of these three technological processes. In addition, the resulting processing treatments are compared to determine which processing treatment is the most environmentally friendly.
The results obtained from the production and processing of 1 kg of the BSF protein are shown in the present section. In the first part, a contribution analysis of the impact categories is presented, followed by a process contribution analysis. Finally, a comparison among the processing treatments studied is shown.
3.1. Contribution Analysis of Impact Categories
Based on the normalized and weighted results, the most relevant impact category was identified as land use, with a cumulative contribution of 99.08, 92.82, 99.04 and 98.87% of all environmental impacts to BOP, BOS, BLP and FOP, respectively. Moreover, energy use, freshwater ecotoxicity, water use and climate change impact categories were selected. The five selected impact categories contributed to 100% of the total environmental impacts in the BOP, BLP and FOP processing treatments, while they contributed to 99.40% in the BOS processing treatment (Table 6
3.2. Processes Contribution Analysis
Environmental impacts were caused by different processes involved in the BSF protein production and processing. Figure 3
and Figure 4
depict the relative contributions of the different processes involved in all the studied impact categories.
Corn and wheat bran cultivation, recollection and processing were found to be the processes with the most significant contribution, accounting for more than 85% of the environmental burdens in the land use impact category for all processing treatments (Figure 3
Regarding the energy use impact category, electricity production and corn grain cultivation processes were the most relevant for the BOP, BLP and FOP processing treatments. In particular, electricity accounted for 65.86% and corn grain cultivation for 17.81% (averaged across the three treatments). For the BOS processing treatment, electricity production accounted for 64.02%, while carbon dioxide production contributed 31.38% of the energy use impact category (Figure 3
In terms of the impact on freshwater ecotoxicity, the key factors for all processing treatments were determined to be electricity production and corn grain cultivation, recollection and processing for the BOP, BLP and FOP processing treatments. On average, these factors accounted for 50.71% and 34.43%, respectively. However, for the BOS group, electricity production was the most relevant contributor, accounting for 81.32% of the impact (Figure 4
Regarding water use, the most significant processes varied among the different processing treatments. For all treatments, corn grain cultivation, recollection and processing, followed by electricity production, were identified as the primary factors. However, their contributions differed significantly. In the case of the BOP, BLP and FOP processing treatments, corn cultivation accounted for 56.62%, while electricity production contributed 33.17% to water use. In contrast, for the BOS processing treatment, electricity production was the dominant factor, accounting for 78.18%, followed by corn cultivation, which contributed 18.22% (Figure 4
In terms of the climate change impact category, electricity production and corn cultivation were found to be the most significant processes across all BOP, BLP and FOP groups, contributing over 80% of the environmental burdens. In the case of the BOS experimental group, electricity production (71.34%) and CO2
production (20.32%) were identified as the primary contributors to the climate change impact category (Figure 4
3.3. Comparison of Processing Treatments
In the following section, the production and processing of 1 kg of the BSF protein using standard and alternative insect processing technologies are analyzed and compared. The results obtained in the comparison of 1 kg of the BSF protein obtained through the combination of the different technologies are shown in Table 7
The environmental impacts of the BOS treatment were consistently higher across all selected impact categories. Specifically, land use, energy use, freshwater ecotoxicity, water use and climate change were observed to be 1.07, 8.72, 4.70, 3.11 and 6.34 times higher, respectively, compared to the BOP control group, which served as the benchmark insect processing technology.
In contrast, both the BLP and BOP processing treatments demonstrated comparable environmental performance across all selected impact categories. However, the FOP processing treatment exhibited superior environmental performance in all selected impact categories. Specifically, land use, energy use, freshwater ecotoxicity, water use and climate change were found to be 1.84, 1.50, 1.58, 1.68 and 1.55 times lower, respectively, compared to the BOP processing treatment. In general, the outcomes of this investigation indicated that the FOP treatment displayed lower environmental impacts across all selected impact categories, whereas the BOS treatment consistently demonstrated higher impacts compared to the other treatments under examination.
This study investigates and compares different processing technologies for insect protein production in terms of their environmental impacts. It particular, it aims to contribute to the development of sustainable and efficient insect value chains by analyzing the potential environmental burdens associated with each processing method. The BOS treatment consistently had higher environmental impacts mostly due to energy-intensive CO2-based extraction, whereas the FOP processing was the eco-friendliest, with lower impacts across all categories, indicating its potential for improving insect protein production’s environmental impact through optimized processing.
The selection of impact categories in LCA studies for insect production may vary de-pending on the specific context and objectives of the study. Nevertheless, common impact categories examined in insect production include land use, climate change, energy use and water use, as supported by previous studies [24
]. Similarly, the most relevant impact categories identified in this study included land use, energy use, freshwater ecotoxicity, water use and climate change. These categories were chosen based on their relevance to the environmental impacts associated with insect protein production and processing. In particular, the analysis performed in this study revealed that land use had the highest contribution to the overall environmental impact across all processing treatments studied.
The analysis of process contributions provided insights into the specific stages that significantly influenced the environmental impacts of the processing treatments. Corn and wheat bran cultivation, collection and processing emerged as the most relevant processes across several impact categories, particularly land use. In this particular case, corn and wheat bran cultivation environmental impacts were attributed to land occupation. Considering that corn and wheat were destined for a BSF feed substrate, alternative feeds must be considered and further studied, as was reported in previous studies [5
]. These findings emphasize the need for sustainable sourcing practices and efficient resource management in the insect industry, such as optimizing feed production. Moreover, electricity production was consistently identified as a significant process contributing to multiple impact categories, in particular climate change, freshwater ecotoxicity and energy use. This highlights the importance of transitioning towards renewable energy sources to reduce the environmental burden associated with insect production.
The comparison of processing treatments revealed important differences in their environmental performance. The BOS treatment consistently demonstrated higher environmental impacts across all selected categories compared to the BOP control group. These elevated impacts can be attributed primarily to the substantial energy demand associated with SFE extraction using CO2, which emerged as the key driver behind these findings. In this sense, the SFE extraction process can have a high energy demand due to several contributing factors, such as high pressure and temperature requirements, compression of supercritical fluid, heat transfer, cooling, etc. On the other hand, both the BLP and BOP treatments showed comparable environmental performance, indicating that the use of alternative drying methods (lyophilization) did not significantly affect the overall environmental impacts when compared to the standard processing technologies. The FOP processing treatment stood out as the most environmentally friendly option among the evaluated processing treatments. It exhibited lower environmental impacts in all selected categories compared to the rest of processing treatment. These results suggest that replacing the sacrifice step with freezing instead of blanching has the potential to enhance the environmental performance of insect processing. The freezing–oven drying–hot pressing combination proved to be a more sustainable approach, suggesting that optimizing the processing sequence can lead to improved environmental performance in insect protein production.
In conclusion, this study shed light on the environmental impacts of different processing treatments for insect protein production. By analyzing the contributions of various impact categories and processes, valuable insights were gained regarding the sustainability of insect protein production and the importance of selecting appropriate processing technologies, offering valuable insights for stakeholders, decision makers and researchers. Throughout this manuscript, it is evident that different combinations of processes significantly influenced both environmental impacts and the efficiency of fat and protein extraction, as illustrated in the inventory data. From an environmental standpoint, the results highlighted the most environmentally favorable operational processes for insect protein production while pinpointing critical areas for improvement, primarily related to the raw materials utilized for insect feed. These findings provide guidance for decision makers, emphasizing the importance of considering the use of secondary raw materials for insect feed. Consequently, future research should prioritize demonstrating the safety of such materials for the insect sector. This approach has the potential to mitigate the primary environmental impact category identified in this study: land use.