Insect Extracts Research Articles

Biological activity and processing technologies of edible insects: a review.

The burgeoning global population growth has raised concerns regarding the expected increase in the demand for food, which could be partially tackled by identifying novel food sources. To this end, edible insects have recently attracted research interest. Several technologies for utilizing edible insect-derived proteins have been introduced; however, research into their functional utilization is insufficient. Herein, we reviewed the relevant literature on the importance of insects as food sources, extraction of edible insects, the nutritional value of insects, biological activities of components, and their applications in food industries. We summarized the studies primarily focused on the functional utilization of edible insects, suggesting that for successful incorporation and growth of edible insects in food and pharmaceutical industries, strategies to improve the extraction methods are required to explore the biological activity of edible insects. Furthermore, the awareness of edible insects with a focus on their allergens warrants consideration.

Antiparasitic Effects of Potentially Toxic Beetles (Tenebrionidae and Meloidae) from Steppe Zones.

Arthropods and specifically beetles can synthesize and/or sequester metabolites from dietary sources. In beetle families such as Tenebrionidae and Meloidae, a few studies have reported species with toxic defensive substances and antiparasitic properties that are consumed by birds. Here we have studied the antiparasitic activity of extracts from beetle species present in the habitat of the Great Bustard (Otis tarda) against four pathogen models (Aspergillus niger, Meloidogyne javanica, Hyalomma lusitanicum, and Trichomonas gallinae). The insect species extracted were Tentyria peiroleri, Scaurus uncinus, Blaps lethifera (Tenebrionidae), and Mylabris quadripunctata (Meloidae). M. quadripunctata exhibited potent activity against M. javanica and T. gallinae, while T. peiroleri exhibited moderate antiprotozoal activity. The chemical composition of the insect extracts was studied by gas chromatography coupled with mass spectrometry (GC-MS) analysis. The most abundant compounds in the four beetle extracts were hydrocarbons and fatty acids such as palmitic acid, myristic acid and methyl linoleate, which are characteristic of insect cuticles. The presence of cantharidin (CTD) in the M. quadripunctata meloid and ethyl oleate (EO) in T. peiroleri accounted for the bioactivity of their extracts.

Soil characteristics and nutritional traits of Mactrotermes natalensis (Isoptera: Macrotermitinae) as indicators of nutritional quality in Zimbabwe

Macrotermes natalensis is a widely consumed edible termite species that inhabits termitaria of different soil colours in southern Africa. However, there is paucity of data regarding the relationship between termitaria soil properties, nutritional composition and safety for edible soldier termites. We hypothesised that soil properties viz. metal composition, and colour are positively correlated to mineral composition, bioactive compounds and level of contamination by heavy metals in soldier termites. Replicated insects samples were collected from termitaria of different soil colour types from Bikita district, Zimbabwe. Soil and insect mineral composition were determined using standard methods. Antioxidant properties of methanol insect extracts were estimated using the DPPH test. A cluster analysis was performed to relate soil colour to soil and insect minerals compositions and DPPH. Soil Zn and Cu significantly varied (P 50%) was independent of soil colour, soil and insect mineral composition. There is a possible risk of Pb poisoning associated with consumption of soldier Macrotermes natalensis irrespective of termitaria soil colour; however, the risk is more pronounced in insects gathered from yellowish-brown soils.

DNA BARCODING OF COMMON MALAYSIAN SPIDERS USING THE CYTOCHROME OXIDASE I (COI) GENE

For the last twenty years, many newly described spiders were collected from Malaysia and in fact, more than 11,000 species were recorded in Peninsular Malaysia as well as in Sabah and Sarawak states. Scientists have put an immense effort on untangling the spider biology from its physical structure and behavior to silks and venoms. However, working with spiders is impeded by the difficulties in species identification via solely morphological methods. Thus, DNA barcoding is an alternative technique that employs standard fragment to facilitate species identification. Isolation of genomic DNA from three Malaysian spiders were performed using NucleoSpin® DNA insect extraction kit. Amplification of reference mitochondrial cytochrome oxidase I (COI) gene employing PCR with two set of primers followed by the DNA sequencing and validation through phylogenetic analysis were carried out. The commercial extraction kit was effective for the recovery of good quality of intact genomic DNA band as indicated by the integrity analysis. Both set of primers successfully amplified 100% of the samples with approximately 600 – 700 bp of PCR products. The obtained sequences (610 bp to 692 bp) were compared with the sequences available in Gene Bank. BLAST and phylogenetic analysis revealed that the analyzed individual samples belong to Nephila pilipes, Neoscona nautica and Crossopriza lyoni, respectively. Phylogenetic analysis provided unique insight into the evolutionary relationship of each analyzed sample. This study aids in an accurate identification of the selected local spider species at molecular level using the COI gene.

Beneficial Effects of Insect Extracts on Nonalcoholic Fatty Liver Disease.

It is well known that nonalcoholic fatty liver disease (NAFLD) is a common disease worldwide because of unhealthy changes in dietary habits. In this study, we determined the effects of Tenebrio molitor Linnaeus, 1758 extract (TML) and Allomyrina dichotoma Linnaeus, 1771 larvae extract (ADL) in cellular and animal models. In vitro, TML and ADL treatments did not cause cytotoxicity, but attenuated the accumulation of lipid in HepG2 cells induced by free fatty acids. In vivo, mice were orally treated with TML and ADL for 10 weeks during high-fat diet feeding. TML and ADL administration significantly reduced the weight of body, liver tissue, and adipose tissue. Serum lipid profiles, hepatic functional parameters, and glucose levels were ameliorated by TML and ADL. Moreover, TML and ADL suppressed increased lipogenesis and inflammation-related makers, and improved antioxidant enzyme activity. In liver tissue, the decreased lipid accumulation by administration of TML and ADL was observed using Oil Red O and Hematoxylin and Eosin staining. Therefore, we suggest that TML and ADL may be having a therapeutic potential and is used to develop a therapeutic agent for NAFLD.

Anti-Thrombotic, Anti-Oxidant and Haemolysis Activities of Six Edible Insect Species.

In Korea, various insect species such as crickets and grasshoppers, as well as honey bee and silkworm pupae, have been consumed as food and used in oriental medicine. In this study to evaluate useful the bioactivities and potentially adverse effects of edible insects, ethanol extracts of Allomyrina dichotoma (AD), Tenebrio molitor (TM), Protaetia brevitarsis (PB), Gryllus bimaculatus (GB), Teleogryllus emma (TE), and Apis mellifera (AM) were prepared and evaluated with regard to their anti-thrombosis, anti-oxidant and haemolysis activities against human red blood cells. AD and TE extracts showed strong anti-oxidant activities, which were not related to polyphenol content. All ethanol extracts, except AM extract, showed strong platelet aggregation activities. The platelet aggregation ratios of the extracts were 194%–246% of those of the solvent controls. The effects of the AD, TM, PB, GM, and AM extracts on thrombin, prothrombin and various coagulation factors were negligible. Only the extract of TM showed concentration-dependent anti-coagulation activities, with a 1.75-fold aPTT (activated Partial Thromboplastin Time) extension at 5 mg/mL. Of the six insect extracts, TM and AM extracts exhibited potent haemolytic activity. Our results on the insect extracts’ functional properties suggest that edible insects have considerable potential not just as a food source but as a novel bio-resource as well.

Integrative Metabolomics for Assessing the Effect of Insect (Hermetia illucens) Protein Extract on Rainbow Trout Metabolism

Nutrition of high trophic species in aquaculture is faced with the development of sustainable plant-based diets. Insects seem particularly promising for supplementing plant-based diets. However, the complex effect of whole insect meal on fish metabolism is not well understood, and even less is known about insect meal extracts. The purpose of this work was to decipher the metabolic utilization of a plant-based diet supplemented with the gradual addition of an insect protein extract (insect hydrolysate at 0%, 5%, 10% and 15%). 1H-NMR profiling was used to assess metabolites in experimental diets and in fish plasma, liver and muscle. A significant dose-dependent increase in growth and feed efficiency with increasing insect extract amounts was observed. The incremental incorporation of the insect extract in diet had a significant and progressive impact on the profile of dietary soluble compounds and trout metabolome. The metabolites modulated by dietary insect extracts in plasma and tissues were involved in protein and energy metabolism. This was associated with the efficient metabolic use of dietary free amino acids toward protein synthesis through the concomitant supply of balanced free amino acids and energy substrates in muscle. The findings provide new insights into how the dietary food metabolome affects fish metabolism.

Extracts from the edible insects Acheta domesticus and Tenebrio molitor with improved fatty acid profile due to ultrasound assisted or pressurized liquid extraction

Extracts from the edible insects Acheta domesticus and Tenebrio molitor were obtained by ultrasound-assisted extraction (UAE) and pressurized-liquid extraction (PLE) using ethanol (E) or ethanol:water (E:W). Extraction yield, fatty acid profile, nutritional impact and cholesterol content were determined and compared with the initial insects. The highest extraction yield corresponded to PLE-T. molitor extracts. A decrease in total saturated fatty acid (SFA) and monounsaturated fatty acid (MUFA) contents, and an increase in the total polyunsaturated fatty acid (PUFA) content were observed for both UAE-E:W insect extracts, due to an enrichment in linoleic acid. The lipid indices (PUFA/SFA ratio, atherogenic and thrombogenic indices) for both UAE-E:W extracts were significantly improved compared with the initial insects. Although either extraction procedure led to cholesterol enrichment, the UAE-E:W conditions favoured the lowest concentration. Therefore, insects extracts with improved fatty acid profile can be selectively obtained, being UAE-E:W conditions preferred from the nutritional point of view.

Efficacy of D-Glucose-13C6 as a Label for Amino Acid Identification and Quantification in Mediterranean Fruit Flies (Diptera: Tephritidae)

The efficacy of D-glucose labeled with 13C6 (D-glucose-13C6) in the study of amino acid metabolism in insects was determined by incorporating either D-glucose-13C6 or unlabeled D-glucose into larval and adult diets of the Mediterranean fruit fly (medfly), Ceratitis capitata (Wiedemann) (Diptera: Tephritidae). Feeding treatments were: (a) labeled glucose diet for larvae + unlabeled glucose diet for adults; (b) unlabeled glucose diet for larvae + labeled glucose diet for adults; (c) labeled glucose diet for larvae + labeled glucose diet for adults; and (d) unlabeled glucose diet for larvae + unlabeled glucose diet for adults. Amino acid content of extracts from unmated adults and mated adults was determined with gas chromatography-mass spectrometry (GC-MS). L-alanine, L-aspartic acid, L-cysteine, L-glutamic acid, L-glycine, L-isoleucine, L-leucine, L-methionine, L-proline, L-phenylalanine, L-serine, L-threonine, L-tyrosine, and L-valine were identified from the insect extracts. In the treatment that fed unlabeled glucose larval and adult diets (control), amino acid content was lower after mating than before mating except for L-cysteine (e.g., 13-fold increase). Amino acid content in insects fed D-glucose-13C6 also decreased after mating except for L-valine, L-leucine, L-tyrosine, and L-isoleucine, all of which remained comparatively equal before and after mating, and L-threonine which increased almost 12-fold after mating. Only trace amounts of L-tyrosine and L-isoleucine were detected before and after mating in those fed labeled diets. These results suggest that stable isotopes can be used as labels for insect metabolic studies.

A Rapid, Simple, Laboratory and Field-Adaptable DNA Extraction and Diagnostic Method Suitable for Insect-Transmitted Plant Pathogen and Insect Identification

Watch a presentation about this research by first author Karolina Pusz-Bochenska. Surveillance for insect-transmitted pathogens of plants involves sampling insects in the field, followed by transport of the samples to the laboratory for DNA extraction and molecular analysis. Sample transport and DNA extraction are time consuming and can delay the implementation of measures to mitigate the effects of insect-transmitted plant pathogens. Looking for a fast and reliable method to extract DNA in the field where insects were collected, we used Flinders Technology Associates PlantSaver cards, which are designed for plant DNA extraction. Insect DNA extraction can be achieved in the field, and extracted DNA can be amplified using the field-adaptable method, loop-mediated isothermal amplification (LAMP), in less than 1 h. Additionally, we demonstrate the feasibility and accuracy of the paper extraction method for molecular identification to the species level using mitochondrial cytochrome oxidase 1 amplification and sequencing on 11 genera of insects including beetles, leafhoppers, flies, psyllids, and aphids. The method was suitable for insects collected using three common methods: live-trapped and frozen, stored in ethanol, or trapped on sticky cards. Moreover, by testing leafhoppers collected in 2018 in the field, we demonstrated that the LAMP assay using the chaperonin-60 target detects a higher proportion of samples positive for ‘Candidatus Phytoplasma asteris’ than conventional PCR targeting 16S rRNA. Lastly, the paper extraction method was used to determine the prevalence of leafhoppers carrying the plant pathogenic bacterium ‘Ca. P. asteris’, which causes aster yellows from a laboratory-reared colony using PCR-based tests (conventional PCR, qPCR, and droplet digital PCR) and the non-PCR-based LAMP assay.

Improvement of Insect Tea Extract on D-galactose Induced Aging in Mice

Milk fat globule-EGF factor 8 (MFG-E8) is one of the major proteins in milk fat globule membrane. In this study, mouse-derived C2C12 myoblast cells were served as an experimentally tractable model system for investigating the molecular basis of skeletal muscle cell specification and development. To examine the biochemical adaptations associated with myocytes formation comprehensively, a liquid chromatography coupled with tandem mass spectrometry label-free semi-quantitative approach was used to analyse the myogenic C2C12 proliferation program. Over 1987 proteins were identified in C2C12 cells. The MFG-E8 (200 μg/mL) and MFG-E8 (500 μg/mL) with significant differences were compared based on the relative abundance. The result profiles of regulation of MFG-E8 to the expression of proteins in C2C12 cells revealed that differential waves of expression of proteins linked to intracellular signaling, transcription, cytoarchitecture, adhesion, metabolism, and muscle contraction across during the C2C12 cell proliferation process. Based on the analysis of KEGG and STRING database, further to verification the expression of PI3K and ERK phosphorylation levels by Western blot. This study found that the data of proteomic was complementary to recent MFG-E8 studies of protein expression patterns in developing myotubes and provided a holistic framework for understanding how diverse biochemical processes are coordinated at the cellular level during skeletal muscle development.

Characterization, antioxidant activity, and inhibitory effect on pancreatic lipase of extracts from the edible insects Acheta domesticus and Tenebrio molitor

Extracts from the edible insects Acheta domesticus and Tenebrio molitor were obtained by ultrasound-assisted extraction (UAE) and pressurized-liquid extraction (PLE) using ethanol (E) or ethanol:water (E:W). Characterization by GC–MS was performed and total phenolic compounds (TPC), antioxidant activity (DPPH) and pancreatic lipase inhibitory capacity were assayed.Most extracts, mainly ethanolic extracts, predominantly presented lipids as free fatty acids, followed by aminoacids, organic acids, carbohydrates, hydrocarbons and sterols. The UAE-E:W extracts were different, being characterized by organic acids for A. domesticus, or aminoacids for T. molitor. All the extracts exhibited antioxidant activity, which correlated with TPC values, being the E:W extracts the most effective. All the extracts showed inhibitory activity of lipase, although those from T. molitor and extracted by PLE were the most effective.Therefore, bioactive insect extracts can be selectively obtained by advanced methods of extraction, being aqueous ethanol preferred for antioxidant activity and PLE for inhibitory lipase activity.

Anti-Photoaging Effects of Four Insect Extracts by Downregulating Matrix Metalloproteinase Expression via Mitogen-Activated Protein Kinase-Dependent Signaling.

Insects are some of the most diverse organisms on the planet, and have potential value as food or medicine. Here, we investigated the photoprotective properties of insect extracts using hairless mice. The alleviating wrinkle formation effects of insect extracts were evaluated by histological skin analysis to determine epidermal thickness and identify collagen fiber damage. Moreover, we investigated the ability of the insect extracts to alleviate UVB-induced changes to matrix metalloproteinases (MMPs), oxidative damage, the mitogen-activated protein kinases (MAPKs) signaling pathway, and the expression of pro-inflammatory cytokines. Insect extracts reduced UVB-induced skin winkles, epidermal thickening, and collagen breakdown, and alleviated the epidermal barrier dysfunction induced by UVB, including the increased loss of transepidermal water. Moreover, the expression of skin hydration-related markers such as hyaluronic acid, transforming growth factor-beta (TGF-β), and procollagen was upregulated in the group treated with insect extracts compared to the vehicle-treated group after ultraviolet B (UVB) exposure. UVB irradiation also upregulated the expression of MMPs, the phosphorylation of MAPKs, and pro-inflammatory cytokines, which were all attenuated by the oral administration of insect extracts. These results indicate the photoaging protection effect of insect extracts and the underlying mechanism, demonstrating the potential for clinical development.

Edible insects: Cross-recognition of IgE from crustacean- and house dust mite allergic patients, and reduction of allergenicity by food processing

BackgroundInsects have become increasingly interesting as alternative nutrient sources for feeding humans and animals, most reasonably in processed form. Initially, some safety aspects — among them allergenicity — need to be addressed. ObjectiveTo reveal the cross-reactivity of shrimp-, mite- and flies-allergic patients to different edible insects, and further to assess the efficacy of food processing in reducing the recognition of insect proteins by patients' IgE and in skin prick testing of shrimp-allergic patients. MethodsIgE from patients allergic to crustaceans, house dust mite or flies was evaluated for cross-recognition of proteins in house cricket Acheta domesticus (AD), desert locust Schistocerca gregaria (SG) and Yellow mealworm Tenebrio molitor (TM). Changes in IgE-binding and SPT-reactivity to processed insect extracts were determined for migratory locust (Locusta migratoria, LM), after different extraction methods, enzymatic hydrolysis, and thermal processing were applied. ResultsIgE from patients with crustacean-allergy shows cross-recognition of AD, SG and stable flies; house dust mite allergics' IgE binds to AD and SG; and the flies-allergic patient recognized cricket, desert locust and migratory locust. Cross-reactivity and allergenicity in SPT to LM can be deleted by conventional processing steps, such as hydrolysis with different enzymes or heat treatment, during the preparation of protein concentrates. ConclusionThe results show that crustacean-, HDM- and stable flies-allergic patients cross-recognize desert locust and house cricket proteins, and crustacean-allergic patients also flies proteins. Furthermore, this study shows that appropriate food processing methods can reduce the risk of cross-reactivity and allergenicity of edible insects.

Fungal Communities Associated with Bark Beetles in Pinus radiata Plantations in Northern Spain Affected by Pine Pitch Canker, with Special Focus on Fusarium Species

Fusarium spp., as well as other endophytic or pathogenic fungi that form communities, have been reported to be phoretically associated with bark beetles (Coleoptera; Scolytinae) worldwide. This applies to Fusarium circinatum Nirenberg and O’Donnell, the causal agent of pine pitch canker (PPC), which threatens Pinus radiata D. Don plantations in northern Spain. The main objective of this study was to study the fungal communities associated with bark beetles and their galleries in stands affected by PPC, with special attention given to Fusarium species. Funnel traps and logs were placed in a P. radiata plot known to be affected by F. circinatum. The traps were baited with different attractants: four with (E)-pityol and six with ethanol and α-Pinene. In addition, fresh green shoots with Tomicus piniperda L. feeding galleries were collected from the ground in 25 P. radiata plots affected by PPC. Extracts of whole insects and gallery tissues were plated on agar medium to isolate and identify the associated fungi. A total of 24 different fungal species were isolated from the bark beetle galleries constructed in logs and shoots, while 18 were isolated from the insect exoskeletons. Ten different Fusarium species were isolated from tissue and insects. Fusarium circinatum was isolated from bark beetle exoskeletons (1.05% of the Pityophthorus pubescens Marsham specimens harboured F. circinatum) and from the galleries (3.5% of the T. piniperda feeding galleries harboured the pathogen). The findings provide information about the fungal communities associated with bark beetles in P. radiata stands in northern Spain.

Hepatoprotective Effects of Insect Extracts in an Animal Model of Nonalcoholic Fatty Liver Disease.

Insects represent the largest and most diverse group of organisms on earth and are potential food and drug resources. Recently, we have demonstrated that a Forsythia viridissima extract prevented free fatty acid-induced lipid accumulation in an in vitro cellular nonalcoholic fatty liver disease (NAFLD) model. In this study, we aimed to evaluate the hepatoprotective effects of extracts of the insects Protaetia brevitarsis seulensis Kolbe, 1886 (PB), Oxya chinensis sinuosa Mishchenko, 1951 (OC), and Gryllus bimaculatus De Geer, 1773 (GB) in a high-fat diet (HFD)-induced NAFLD animal model, as well as to elucidate the underlying mechanisms. The effects of the supplementation with PB, OC, and GB extracts were evaluated histopathologically and histochemically. PB, OC, and GB extract supplementation inhibited the HFD-induced increase in body weight and body fat mass and ameliorated other adverse changes, resulting in decreased liver function parameters, lower serum triglyceride and cholesterol levels, and increased serum adiponectin levels. The expression of hepatic genes involved in lipid droplet accumulation and in fatty acid uptake also decreased upon treatment of HFD-fed mice with the extracts. These results provide evidence of the protective effects of the PB, OC, and GB extracts against HFD-induced fatty liver disease in an animal model.

Application of synchrotron radiation phase-contrast microtomography with iodine staining to Rhodnius prolixus head during ecdysis period

Synchrotron radiation phase-contrast microtomography (SR-PHC-CT) has become an important tool in studies of insects, mainly Rhodinius prolixus, the insect vector of Chagas disease. A previous work has shown that SR-PHC-CT is an excellent technique in studies about the ecdysis process of R.prolixus head. The term ecdysis refers to the set of behaviors by which an insect extracts itself from an old exoskeleton. The exoskeleton formation is indispensable for the evolutionary success of insect species, so failure to complete ecdysis will, in most cases result in death, making this process an excellent target in the search for new insect pest management strategies. Understanding the behavior of the ecdysis process is fundamental for the non-proliferation of Chagas disease. Despite it has been possible to identify the moulting process in the first work, main structures of the R.prolixus head could not be identified. In this work, it was developed a staining protocol which enabled the identification of these important structures using Iodine at SYRMEP beamline of ELETTRA. In the 3D images, it was possible to segment essential structures in the process of ecdysis. These structures have never been presented previously in the moulting period with SR-PHC-CT.

Involvement of phenoloxidase in browning during grinding of Tenebrio molitor larvae.

Insects are investigated as alternative protein source to meet the increasing demand for proteins in the future. Enzymatic browning occurring during grinding of insect and subsequent extraction of proteins can influence the proteins’ properties, but it is unclear which enzymes are responsible for this phenomenon. This study was performed on larvae of three commonly used insect species, namely Tenebrio molitor, Alphitobius diaperinus and Hermetia illucens. Oxygen consumption measurements on protein extracts showed activity on L-tyrosine, L-3,4-di-hydroxy-phenylalanine (L-DOPA) and L-dopamine, indicating phenoloxidase as a key player in browning. Furthermore, no reaction on 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) was observed, ruling out an important contribution of laccase to browning. The browning reaction was most prominent at pH 6 for T. molitor and A. diaperinus, and 7 for H. illucens. As the enzyme activity of H. illucens was the lowest with the darkest color formation, this was likely caused by another factor. The activity of phenoloxidase was confirmed for T. molitor and A. diaperinus by activity measurements after fractionation by anion-exchange chromatography. Color measurements showed the presence of activity on both L-DOPA and L-tyrosine in the same fractions. Both substrates were converted into dopachrome after incubation with enzyme-enriched fractions. No DOPA-decarboxylase, tyrosine hydroxylase and peroxidase activities were observed. By using native PAGE with L-DOPA as staining-solution, active T. molitor protein bands were resolved and characterized, identifying a tyrosinase/phenoloxidase as the active enzyme species. All together, these data confirmed that tyrosinase is an important enzyme in causing enzymatic browning in T. molitor and likely in A. diaperinus.

Studies on the formation of 4-aminocarminic acid

Dried bodies of the female insect Dactylopius coccus Costa were extracted using various extraction solvents. Whereas the amount of extracted carminic acid was between 4 and 24 % of insect material, 4-aminocarminic acid was detected in the extracts in only in low amounts of about 0.1 % of insect material. Compared to ratios of 4-aminocarminic acid to carminic acid, which had been reported to be present in some food additive and beverage samples, ratios in the insect extracts were very low (between 1:211 and 1:154, w/w). However, mixing carminic acid and ammonium hydroxide resulted in formation of significant amounts of 4-aminocarminic acid. Depending on the molar ratio of carminic acid to ammonia, the ratio of 4-aminocarminic acid to carminic acid was up to 1:1.2 (w/w). Spontaneous formation of 4-aminocarminic acid leading to a false positive result was also observed for the analysis of a ketchup sample when ammonia was used during sample preparation.

Interfacial and emulsifying properties of mealworm protein at the oil/water interface

The increasing global population and consumer demand for protein will render the provision of protein a serious future challenge. The lower environmental impact of insect farming makes the consumption of insects an appealing solution, although consumers in developed countries often respond to the idea of eating insects with disgust. One approach to accustom consumers to insects as part of their diet is through the application of functional insect extracts as food ingredients. Here, the interfacial and emulsion properties of protein extracted from Tenebrio molitor (MP) was investigated in comparison to commercial whey protein (WP). The MP showed higher interfacial activity and faster adsorption kinetics at the oil/water interface. The mean droplet size of high shear processed oil-in-water (o/w) emulsions (20% w/w oil) stabilised with MP assumed a process limited value at the lowest protein concentration, included in this study, of 0.44% w/w based on aqueous phase. Stepwise increase in protein concentration to 0.88%, 1.75% and 2.63% revealed, in the case of WP stabilised emulsions, that the same process limited droplet diameter was reached at 1.75% protein addition. With a view to potential future application of MP as a food emulsifier MP stabilised emulsions were exposed to common formulation and process conditions such as varied pH, salt, heat, chilling and freezing. Except for flocculation after heating to 90 °C and at pH close to the isoelectric point (IEP) of the MP, the microstructure of the emulsions remained unchanged. MP shows promise as a food emulsifier and represents a vehicle for the introduction of insect protein into the diet of societies not accustomed to eating insects.