Allergenicity assessment of the edible cricket Acheta domesticus in terms of thermal and gastrointestinal processing and IgE cross-reactivity with shrimp

A systematic review of allergen cross-reactivity: Translating basic concepts into clinical relevance

Access to the molecular culprits of allergic reactions allows for the leveraging of molecular allergology as a new precision medicine approach-one built on interdisciplinary, basic, and clinical knowledge. Molecular allergology relies on the use of allergen molecules as in vitro tools for the diagnosis and management of allergic patients. It complements the conventional approach based on skin and in vitro allergen extract testing. Major applications of molecular allergology comprise accurate identification of the offending allergen thanks to discrimination between genuine sensitization and allergen cross-reactivity, evaluation of potential severity, patient-tailored choice of the adequate allergen immunotherapy, and prediction of its expected efficacy and safety. Allergen cross-reactivity, defined as the recognition of 2 or more allergen molecules by antibodies or T cells of the same specificity, frequently interferes with allergen extract testing. At the mechanistic level, allergen cross-reactivity depends on the allergen, the host's immune response, and the context of their interaction. The multiplicity of allergen molecules and families adds further difficulty. Understanding allergen cross-reactivity at the immunologic level and translating it into a daily tool for the management of allergic patients is further complicated by the ever-increasing number of characterized allergenic molecules, the lack of dedicated resources, and the need for a personalized, patient-centered approach. Conversely, knowledge sharing paves the way for improved clinical use, innovative diagnostic tools, and further interdisciplinary research. Here, we aimed to provide a comprehensive and unbiased state-of-the art systematic review on allergen cross-reactivity. To optimize learning, we enhanced the review with basic, translational, and clinical definitions, clinical vignettes, and an overview of online allergen databases.

Recent advances in edible insect processing technologies

Alternative foods have emerged as one of the hot research topics aiming at alleviating food shortage. Insects are one of the alternative foods due to their rich nutrients. Processing is a critical step to develop insect foods, while there is a lack of comprehensive reviews to summarize the main studies. This review aims to demonstrate different processing methods in terms of their impact on insect nutrition and their potential risks. Heat treatments such as boiling and blanching show a negative effect on insect nutrition, but essential to assure food safety. Insects treated by high-pressure hydrostatic technology (HPP) and cold atmospheric pressure plasma (CAPP) can achieve a similar sterilization effect but retain the nutritional and sensory properties. Drying is a practical processing method for industrial insect production, where oven drying serves as a cost-effective method yielding products comparable in quality to freeze-dried ones. In terms of extraction technology, supercritical carbon dioxide and ultrasound-assisted technology can improve the extraction efficiency of proteins and lipids from insects, enhance the production of composite insect-fortified foods, and thus facilitate the development of the insect food industry. To address the widespread negative perceptions and low acceptance towards insect foods among consumers, the primary development direction of the insect food industry may involve creating composite fortified foods and extracting insect-based food components.

Allergic Reaction to a Commercially Available Insect Snack Caused by House Cricket (Acheta domesticus) Tropomyosin

SCOPE

Edible insects contain allergens with potential cross-reactivity to other invertebrates. Here, this study examines IgE-reactive proteins in a house cricket snack (Acheta domesticus) leading to an allergic reaction in a 27-year old man followed by a similar reaction days later after eating shrimps.

METHODS AND RESULTS

Prick to prick tests verify the IgE-mediated allergy to crickets and skin prick testing confirms a type I sensitization to house dust mite without any clinical relevance for the patient, and to shrimp extracts, but is negative for several other foods. Serological testing reveals a sensitization to shrimps, shrimp tropomyosin, and house dust mite tropomyosin. IgE-immunodetection shows that the cricket allergic patient is sensitized to two proteins of 45 and >97 kDa using aqueous control cricket extract, but to only one protein at around 45 kDa when using the causative, seasoned insect snack extract. Mass spectrometry data and IgE-inhibition experiments clearly identify this protein belonging to the tropomyosin allergen family.

CONCLUSION

This case report suggests that cricket tropomyosin may be an elicitor of allergic reactions even in previously not allergic patients, although it cannot be excluded the patient reacted additionally to other ingredients of the snack.

An analysis of emerging food safety and fraud risks of novel insect proteins within complex supply chains

Food consumption play a crucial role in human life, yet conventional food production and consumption patterns can be detrimental to the environment. Thus, research and development has been directed towards alternative proteins, with edible insects being promising sources. Edible insects have been recognised for their sustainable benefits providing protein, with less emission of greenhouse gas, land and water usage compared to sources, such as beef, chicken, and dairy products. Among the over 2000 known edible insect species, only four, namely yellow mealworm (Tenebrio molitor), migratory locust/grasshopper (Locusta migratoria), grain mould beetle, also known as lesser mealworm which is a larval form of Alphitobius diaperinus (from the family of Tenebrionidae of darkling beetles) and house cricket (Acheta domesticus), are currently authorised in specific products through specific producers in the EU. The expansion of such foods into Western diets face challenges such as consumer barriers, gaps in microbiological and chemical safety hazard data during production and processing, and the potential for fraudulent supply chain activity. The main aim of this study was to map the supply chain, through interviews with personnel along the supply chain, coupled with searches for relevant publications and governmental documents. Thus, the main potential points of food safety and fraud along the edible insect supply chain were identified. Feed substrate was identified as the main area of concern regarding microbiological and chemical food safety and novel processing techniques were forecast to be of most concern for future fraudulent activity. Despite the on-going authorisation of insect species in many countries there are substantial food safety and authenticity information gaps in this industry that need to be addressed before edible insects can be viewed as a safe and sustainable protein sources by Western consumers.

Food allergen detection by mass spectrometry: From common to novel protein ingredients

Food allergens are molecules, mainly proteins, that trigger immune responses in susceptible individuals upon consumption even when they would otherwise be harmless. Symptoms of a food allergy can range from mild to acute; this last effect is a severe and potentially life-threatening reaction. The European Union (EU) has identified 14 common food allergens, but new allergens are likely to emerge with constantly changing food habits. Mass spectrometry (MS) is a promising alternative to traditional antibody-based assays for quantifying multiple allergenic proteins in complex matrices with high sensitivity and selectivity. Here, the main allergenic proteins and the advantages and drawbacks of some MS acquisition protocols, such as multiple reaction monitoring (MRM) and data-dependent analysis (DDA) for identifying and quantifying common allergenic proteins in processed foodstuffs are summarized. Sections dedicated to novel foods like microalgae and insects as new sources of allergenic proteins are included, emphasizing the significance of establishing stable marker peptides and validated methods using database searches. The discussion involves the in-silico digestion of allergenic proteins, providing insights into their potential impact on immunogenicity. Finally, case studies focussing on microalgae highlight the value of MS as an effective analytical tool for ensuring regulatory compliance throughout the food control chain.

Current technologies, regulation, and future perspective of animal product analogs - A review

The purpose of this study was to investigate the recent development of meat analog, industrialization, and the related legal changes worldwide. Summarizing the current status of the industrialization of meat analog, studies on plant-based meat, mycoprotein, and edible insects were mainly conducted to investigate their sensory properties (texture, taste, flavor, and color resembling meat), nutritional and safety evaluations, acquisition method of meat alternatives, and commercialization. Cultured meat is mainly studied for developing muscle satellite cell acquisition and support techniques or materials for the formation of structures. However, these technologies have not reached the level for active industrialization. Even though there are differences in the food categories and labeling between countries, it is common to cause confusion or to relay false information to consumers; therefore, it is important to provide accurate information. In this study, there were some differences in the food classification and food definition (labeling) contents for each country and state depending on the product shape or form, raw materials, and ingredients. Therefore, this study can provide information about the current research available on meat alternatives, improve regulation, and clarify laws related to the meat analog industry, which can potentially grow alongside the livestock industry.

An in silico approach to unveil peptides from Acheta domesticus with potential bioactivity against hypertension, diabetes, cardiac and pulmonary fibrosis

Entomophagy is a sustainable alternative source of proteins for human nutrition. Acheta domesticus is one of the three insect species that complies with the European Union Regulation on novel foods, but to date, there are no reports on their potential bioactive peptides. In this study, an in silico approach was applied to simulate the gastrointestinal (GI) digestion of six A. domesticus proteins and identify new peptides with potential anti-hypertensive and/or anti-diabetic properties, resulting from their capability to inhibit the somatic Angiotensin-I converting enzyme (sACE) and/or dipeptidyl peptidase 4 (DPP-4), respectively. A molecular docking protocol was applied to evaluate the binding interactions between the 43 peptides ranked with high probability of being bioactive and three drug targets: DPP-4 and two catalytic domains (N- and C-) of sACE. Five peptides (AVQPCF, CAIAW, IIIGW, DATW and QIVW) showed high docking scores for both enzymes, suggesting their potential to inhibit the DPP-4 and both catalytic domains of sACE, thus possessing multifunctional bioactive properties. Two peptides (PIVCF and DVW) showed higher docking scores for the N-domain of sACE, indicating a potential action as selective inhibitors and consequently with anti-cardiac and pulmonary fibrosis bioactivities. This is the first study identifying peptides originated from the simulated GI digestion of A. domesticus with potential activities against hypertension, diabetes, cardiac and pulmonary fibrosis.

Alternative Protein Sources and Novel Foods: Benefits, Food Applications and Safety Issues

The increasing size of the human population and the shortage of highly valuable proteinaceous ingredients has prompted the international community to scout for new, sustainable, and natural protein resources from invertebrates (e.g., insects) and underutilized legume crops, unexploited terrestrial and aquatic weeds, and fungi. Insect proteins are known for their nutritional value, being rich in proteins with a good balance of essential amino acids and being a valuable source of essential fatty acids and trace elements. Unconventional legume crops were found rich in nutritional, phytochemical, and therapeutic properties, showing excellent abilities to survive extreme environmental conditions. This review evaluates the recent state of underutilized legume crops, aquatic weeds, fungi, and insects intended as alternative protein sources, from ingredient production to their incorporation in food products, including their food formulations and the functional characteristics of alternative plant-based proteins and edible insect proteins as novel foods. Emphasis is also placed on safety issues due to the presence of anti-nutritional factors and allergenic proteins in insects and/or underutilized legumes. The functional and biological activities of protein hydrolysates from different protein sources are reviewed, along with bioactive peptides displaying antihypertensive, antioxidant, antidiabetic, and/or antimicrobial activity. Due to the healthy properties of these foods for the high abundance of bioactive peptides and phytochemicals, more consumers are expected to turn to vegetarianism or veganism in the future, and the increasing demand for such products will be a challenge for the future.

EAACI Molecular Allergology User's Guide 2.0

Since the discovery of immunoglobulin E (IgE) as a mediator of allergic diseases in 1967, our knowledge about the immunological mechanisms of IgE-mediated allergies has remarkably increased. In addition to understanding the immune response and clinical symptoms, allergy diagnosis and management depend strongly on the precise identification of the elicitors of the IgE-mediated allergic reaction. In the past four decades, innovations in bioscience and technology have facilitated the identification and production of well-defined, highly pure molecules for component-resolved diagnosis (CRD), allowing a personalized diagnosis and management of the allergic disease for individual patients. The first edition of the "EAACI Molecular Allergology User's Guide" (MAUG) in 2016 rapidly became a key reference for clinicians, scientists, and interested readers with a background in allergology, immunology, biology, and medicine. Nevertheless, the field of molecular allergology is moving fast, and after 6 years, a new EAACI Taskforce was established to provide an updated document. The Molecular Allergology User's Guide 2.0 summarizes state-of-the-art information on allergen molecules, their clinical relevance, and their application in diagnostic algorithms for clinical practice. It is designed for both, clinicians and scientists, guiding health care professionals through the overwhelming list of different allergen molecules available for testing. Further, it provides diagnostic algorithms on the clinical relevance of allergenic molecules and gives an overview of their biology, the basic mechanisms of test formats, and the application of tests to measure allergen exposure.

The Review of Cooking, Drying, and Green Extraction Methods on General Nutritional Properties of Mealworms and Locusts

The processing of edible insects as an alternative source of nutrition may be a key driver in the development of a sustainable food and feed system. This review will study two industrial types of insects-mealworms and locusts-and summarize evidence related to the impact of processing on their micro- and macronutritional characteristics. The focus will be on their potential use as food for human consumption as opposed to animal feed. Literature has indicated that these two insects have the potential to provide protein and fat qualities comparable to or better than traditional mammalian sources. For example, mealworms-the larval form of the yellow mealworm beetlepossess a higher fat content, while adult locusts are rich in fibers, especially chitin. However, due to the different matrix and nutrient compositions, the processing of mealworms or locusts at a commercial scale needs to be tailored to minimize nutritional loss and maximize cost efficiency. The stages of preprocessing, cooking, drying, and extraction are the most critical control points for nutritional preservation. Thermal cooking applications such as microwave technology have demonstrated promising results, but the generation of heat may contribute to a certain nutritional loss. In an industrial context, drying using freeze dry is the preferred choice due to its uniformity, but it can be costly while increasing lipid peroxidation. During the extraction of nutrients, the use of green emerging technologies such as high hydrostatic pressure, pulsed electric field, and ultrasound may provide an alternative method to enhance nutrient preservation.

Graphical Abstract

Overcoming obstacles in insect utilization

Edible insects have long been part of human diets in some countries, and they are expected to become an important alternative food source because of their nutritional value and favorable environmental impact. However, insects’ consumption safety and consumer acceptance are still significant barriers to market positioning, mainly in Western regions. Therefore, several processing technologies have been applied to develop insect-based food products and derivatives to increase consumer safety, shelf-life, and sensorial properties, including appearance. The processing pathway for insects as food might then be focused on eliminating such concerns. However, even though there is enough information related to processing techniques for edible insects, the use of the treated material has been limited as a substitute rather than a main constituted nutritional component. Moreover, there is little information about novel technologies and uses of insect derivatives compared to the minimally processed insect, as in the case of flours. This review presents the food safety (biological and chemical hazards) and cultural aspects of difficulties of eating insects and the role of processing raw material, extraction of insect derivatives (lipids and proteins), and food prototypes development on safety and consumer acceptance.

Graphical abstract

Nutritional Composition, Health Benefits, and Application Value of Edible Insects: A Review

For thousands of years, edible insects have been used as food to alleviate hunger and improve malnutrition. Some insects have also been used as medicines because of their therapeutic properties. This is not only due to the high nutritional value of edible insects, but more importantly, the active substances from edible insects have a variety of biofunctional activities. In this paper, we described and summarized the nutritional composition of edible insects and discussed the biological functions of edible insects and their potential benefits for human health. A summary analysis of the findings for each active function confirms that edible insects have the potential to develop functional foods and medicines that are beneficial to humans. In addition, we analyzed the issues that need to be considered in the application of edible insects and the current status of edible insects in food and pharmaceutical applications. We concluded with a discussion of regulations related to edible insects and an outlook on future research and applications of edible insects. By analyzing the current state of research on edible insects, we aim to raise awareness of the use of edible insects to improve human health and thus promote their better use and development.

Recent Insight on Edible Insect Protein: Extraction, Functional Properties, Allergenicity, Bioactivity, and Applications

Due to the recent increase in the human population and the associated shortage of protein resources, it is necessary to find new, sustainable, and natural protein resources from invertebrates (such as insects) and underutilized plants. In most cases, compared to plants (e.g., grains and legumes) and animals (e.g., fish, beef, chicken, lamb, and pork), insect proteins are high in quality in terms of their nutritional value, total protein content, and essential amino acid composition. This review evaluates the recent state of insects as an alternative protein source from production to application; more specifically, it introduces in detail the latest advances in the protein extraction process. As an alternative source of protein in food formulations, the functional characteristics of edible insect protein are comprehensively presented, and the risk of allergy associated with insect protein is also discussed. The biological activity of protein hydrolyzates from different species of insects (Bombyx mori, Hermetia illucens, Acheta domesticus, Tenebrio molitor) are also reviewed, and the hydrolysates (bioactive peptides) are found to have either antihypertensive, antioxidant, antidiabetic, and antimicrobial activity. Finally, the use of edible insect protein in various food applications is presented.

Extraction and Characterization of Protein Concentrates from Limpets (Patella vulgata) and Peptide Release Following Gastrointestinal Digestion

This study investigated the characterization of proteins from the Irish limpet (Patella vulgata) and assessed the in vitro biological activities of hydrolysates obtained following gastrointestinal digestion (INFOGEST) of a limpet protein concentrate (LPC). The physicochemical properties and the digestibility of the LPC were investigated, along with the angiotensin-converting enzyme (ACE) inhibition and antioxidant activities of the LPC-digested samples. All the digested samples examined outperformed the LPC in terms of activity. Peptides were identified using LC-MS/MS after digestion. A total of 38 and 19 peptides were identified in LPC-G and LPC-GI, respectively, using a database search and a de novo approach. Most of the identified peptides had hydrophobic amino acids, which may contribute to their antioxidant and ACE inhibitory activities. The findings of this study showed that LPC has high nutritional quality with good digestibility and could serve as a potential source of antioxidative and ACE inhibitory peptides following gastrointestinal digestion.

Food allergen control: Tropomyosin analysis through electrochemical immunosensing

Regulations of the EU obliges the indication of the presence of allergens on food labels. This work reports the development of an electrochemical immunosensor to determine tropomyosin (TPM) - a major shellfish allergen - prevailing in the muscles of crustacean species. Two linear ranges between the signal and TPM concentration were obtained: between 2.5 and 20 ng mL^-1 and between 30 and 200 ng mL^-1, with a lowest limit of detection of 0.47 ng mL^-1. The selectivity of the optimized immunoassay, tested with other food allergens (e.g., Cyp c 1, a fish allergen), assures the effective detection of TPM, enabling successful control of foodstuff labelling. Several (12) foods, containing high and low TPM concentrations and TPM-free samples, were analysed using the sensor. A conventional ELISA kit and recovery assays were used to evaluate the accuracy of the results.

Development of incurred chocolate bars and broth powder with six fully characterised food allergens as test materials for food allergen analysis

The design and production of incurred test materials are critical for the development and validation of methods for food allergen analysis. This is because production and processing conditions, together with the food matrix, can modify allergens affecting their structure, extractability and detectability. For the ThRAll project, which aims to develop a mass spectrometry-based reference method for the simultaneous accurate quantification of six allergenic ingredients in two hard to analyse matrices. Two highly processed matrices, chocolate bars and broth powder, were selected to incur with six allergenic ingredients (egg, milk, peanut, soy, hazelnut and almond) at 2, 4, 10 and 40 mg total allergenic protein/kg food matrix using a pilot-scale food manufacturing plant. The allergenic activity of the ingredients incurred was verified using food-allergic patient serum/plasma IgE, the homogeneity of the incurred matrices verified and their stability at 4 °C assessed over at least 30-month storage using appropriate enzyme-linked immunosorbent assays (ELISA). Allergens were found at all levels from the chocolate bar and were homogenously distributed, apart from peanut and soy which could only be determined above 4 mg total allergenic ingredient protein/kg. The homogeneity assessment was restricted to analysis of soy, milk and peanut for the broth powder but nevertheless demonstrated that the allergens were homogeneously distributed. All the allergens tested were found to be stable in the incurred matrices for at least 30 months demonstrating they are suitable for method development.

Safety of frozen and dried formulations from whole house crickets (Acheta domesticus) as a Novel food pursuant to Regulation (EU) 2015/2283

Following a request from the European Commission, the EFSA Panel on Nutrition, Novel Food and Food Allergens (NDA) was asked to deliver an opinion on the safety of frozen and dried formulations from house crickets (Acheta domesticus) as a novel food pursuant to Regulation (EU) 2015/2283. The NF is proposed in three formulations: (i) frozen, (ii) dried, (iii) ground. The main components of the NF are protein, fat and fibre (chitin) in the dried form of the NF, and water, protein, fat and fibre (chitin) in the frozen form of the NF. The Panel notes that the concentrations of contaminants in the NF depend on the occurrence levels of these substances in the insect feed. The Panel further notes that there are no safety concerns regarding the stability of the NF if the NF complies with the proposed specification limits during its entire shelf-life. The NF has a high-protein content, although the true protein levels in the NF are overestimated when using the nitrogen-to-protein conversion factor of 6.25, due to the presence of non-protein nitrogen from chitin. The applicant proposed to use the NF in the form of a snack, and as a food ingredient in a number of food products. The target population proposed by the applicant is the general population. The Panel notes that, considering the composition of the NF and the proposed conditions of use, the consumption of the NF is not nutritionally disadvantageous. The Panel notes that no genotoxicity and no subchronic toxicity studies with the NF were provided by the applicant. Considering that no safety concerns arise from the history of use of A. domesticus or from the compositional data of the NF, the Panel identified no other safety concerns than allergenicity. The Panel considers that the consumption of the NF might trigger primary sensitisation to A. domesticus proteins and may cause allergic reactions in subjects allergic to crustaceans, mites and molluscs. Additionally, allergens from the feed may end up in the NF. The Panel concludes that the NF is safe under the proposed uses and use levels.

Allergens from Edible Insects: Cross-reactivity and Effects of Processing

PURPOSE OF REVIEW

The recent introduction of edible insects in Western countries has raised concerns about their safety in terms of allergenic reactions. The characterization of insect allergens, the sensitization and cross-reactivity mechanisms, and the effects of food processing represent crucial information for risk assessment.

RECENT FINDINGS

Allergic reactions to different insects and cross-reactivity with crustacean and inhalant allergens have been described, with the identification of new IgE-binding proteins besides well-known pan-allergens. Depending on the route of sensitization, different potential allergens seem to be involved. Food processing may affect the solubility and the immunoreactivity of insect allergens, with results depending on species and type of proteins. Chemical/enzymatic hydrolysis, in some cases, abolishes immunoreactivity. More studies based on subjects with a confirmed insect allergy are necessary to identify major and minor allergens and the role of the route of sensitization. The effects of processing need to be further investigated to assess the risk associated with the ingestion of insect-containing food products.