Direct identification of edible insects by MALDI-TOF mass spectrometry

Rapid analysis technologies with chemometrics for food authenticity field: A review

In recent years, the problem of food adulteration has become increasingly rampant, seriously hindering the development of food production, consumption, and management. The common analytical methods used to determine food authenticity present challenges, such as complicated analysis processes and time-consuming procedures, necessitating the development of rapid, efficient analysis technology for food authentication. Spectroscopic techniques, ambient ionization mass spectrometry (AIMS), electronic sensors, and DNA-based technology have gradually been applied for food authentication due to advantages such as rapid analysis and simple operation. This paper summarizes the current research on rapid food authenticity analysis technology from three perspectives, including breeds or species determination, quality fraud detection, and geographical origin identification, and introduces chemometrics method adapted to rapid analysis techniques. It aims to promote the development of rapid analysis technology in the food authenticity field.

Development of real-time PCR method for rapid and accurate detection of Centipedes (Scolopendra mutilans) in food

Centipedes contain pharmacologically active compounds used as important medicinal material. However, the poisons produced by centipedes can cause human diseases; therefore, its use as a food ingredient is prohibited. This is the first report to develop a real-time PCR method for detection of centipedes. The primer and probe targeting the mitochondrial cytochrome c oxidase subunit 1 (COI) gene were newly designed. The specificity was verified using ten species and was confirmed to amplify only the centipede species. The real-time PCR method exhibited good linearity with a high-determination coefficient (R 2 = 0.999) and a detection limit was 0.001 ng. The performance of our method was also verified using five real-time PCR platforms under Universal and Fast PCR conditions. Finally, its applicability to processed food was evaluated using binary insect mixtures, and at least 0.1% of centipedes was detected. Therefore, our method can specifically and sensitively detect centipedes in food, contributing to food safety.

Authentication of Edible Insects’ Powders by the Combination of DART-HRMS Signatures: The First Application of Ambient Mass Spectrometry to Screening of Novel Food

This feasibility study reports the use of direct analysis in real-time high-resolution mass spectrometry (DART-HRMS) in profiling the powders from edible insects, as well as the potential for the identification of different insect species by classification modeling. The basis of this study is the revolution that has occurred in the field of analytical chemistry, with the improved capability of ambient mass spectrometry to authenticate food matrices. In this study, we applied DART-HRMS, coupled with mid-level data fusion and a learning method, to discriminate between Acheta domesticus (house cricket), Tenebrio molitor (yellow mealworm), Locusta migratoria (migratory locust), and Bombyx mori (silk moth). A distinct metabolic fingerprint was observed for each edible insect species, while the Bombyx mori fingerprint was characterized by highly abundant linolenic acid and quinic acid; palmitic and oleic acids are the statistically predominant fatty acids in black soldier fly (Hermetia illucens). Our chemometrics also revealed that the amino acid proline is a discriminant molecule in Tenebrio molitor, whereas palmitic and linoleic acids are the most informative molecular features of the house cricket (Acheta domesticus). Good separation between the four different insect species was achieved, and cross-validation gave 100% correct identification for all training samples. The performance of the random forest classifier was examined on a test set and produced excellent results, in terms of overall accuracy, sensitivity, and specificity. These results demonstrate the reliability of the DART-HRMS as a screening method in a future quality control scenario to detect complete substitution of insect powders.

Detection of Alphitobius diaperinus by Real-Time Polymerase Chain Reaction With a Single-Copy Gene Target

Use of edible insects as an alternative source of proteins in food and feed is increasing. These last years, numerous companies in Europe have started producing insects for food and feed purposes. In the European Union, the use of edible insects for human consumption falls within Regulation (EU) No. 2015/2283 on novel foods. For feed, Commission Regulation (EU) 2017/893 authorizes seven insect species as processed animal proteins for aquaculture. Methods of authentication are required to check the conformity of the products. In this study, we propose a real-time polymerase chain reaction (PCR) method for the specific detection of the lesser mealworm (Alphitobius diaperinus), one of the species included in the shortlist of authorized insects. The selected target is the cadherin gene with a single-copy (per haploid genome) illustrated by our experimental evidence. The PCR test amplified a 134-bp fragment of the cadherin gene. The qualitative method was assessed toward several performance criteria. Specificity was checked against 54 insect species next to other animal and plant species. The sensitivity, efficiency, robustness, and transferability of the PCR assay were also successfully tested. Finally, the applicability of the test was assessed on real-life processed samples (industrial meals) of A. diaperinus. The study also showed that there seems to be a huge confusion on the correct labeling of the marketed mealworms. We did not succeed to get Alphitobius laevigatus samples. They all appeared to belong to the A. diaperinus taxon.

ATR-FTIR Spectroscopy Combined with Multivariate Analysis Successfully Discriminates Raw Doughs and Baked 3D-Printed Snacks Enriched with Edible Insect Powder

In a preliminary study, commercial insect powders were successfully identified using infrared spectroscopy combined with multivariate analysis. Nonetheless, it is necessary to check if this technology is capable of discriminating, predicting, and quantifying insect species once they are used as an ingredient in food products. The objective of this research was to study the potential of using attenuated total reflection Fourier transform mid-infrared spectroscopy (ATR-FTMIR) combined with multivariate analysis to discriminate doughs and 3D-printed baked snacks, enriched with Alphitobius diaperinus and Locusta migratoria powders. Several doughs were made with a variable amount of insect powder (0–13.9%) replacing the same amount of chickpea flour (46–32%). The spectral data were analyzed using soft independent modeling of class analogy (SIMCA) and partial least squares regression (PLSR) algorithms. SIMCA models successfully discriminated the insect species used to prepare the doughs and snacks. Discrimination was mainly associated with lipids, proteins, and chitin. PLSR models predicted the percentage of insect powder added to the dough and the snacks, with determination coefficients of 0.972, 0.979, and 0.994 and a standard error of prediction of 1.24, 1.08, and 1.90%, respectively. ATR-FTMIR combined with multivariate analysis has a high potential as a new tool in insect product authentication.

MALDI-TOF Mass Spectrometry Applications for Food Fraud Detection

Chemical analysis of food products relating to the detection of the most common frauds is a complex task due to the complexity of the matrices and the unknown nature of most processes. Moreover, frauds are becoming more and more sophisticated, making the development of reliable, rapid, cost-effective new analytical methods for food control even more pressing. Over the years, MALDI-TOF MS has demonstrated the potential to meet this need, also due to a series of undeniable intrinsic advantages including ease of use, fast data collection, and capability to obtain valuable information even from complex samples subjected to simple pre-treatment procedures. These features have been conveniently exploited in the field of food frauds in several matrices, including milk and dairy products, oils, fish and seafood, meat, fruit, vegetables, and a few other categories. The present review provides a comprehensive overview of the existing MALDI-based applications for food quality assessment and detection of adulterations.

Peptide fingerprinting of Hermetia illucens and Alphitobius diaperinus: Identification of insect species-specific marker peptides for authentication in food and feed

Insects have been proposed as new source of proteins to meet the growing demand connected to the increasing world population. In the EU the inclusion of insect proteins in feed and food is strictly regulated. Hence, analytical methods able to discriminate and identify different insect species in food and feed are a necessity. In this work, a peptidomic approach was applied to determine peptide biomarkers for two edible insect species: lesser mealworm and black soldier fly. Three species specific peptide biomarkers were identified using LC-MS/MS. The two insects were mixed with fish standard feed at different concentrations, to evaluate the feasibility of their use as markers in complex matrices. The detection of marker peptides was confirmed down to 1% insect amount. The data here reported constitutes the first proof of concept for the potential application of the peptide marker approach for the identification and quantification of insect ingredients.

DNA barcoding reveals incorrect labelling of insects sold as food in the UK

Background

Insects form an established part of the diet in many parts of the world and insect food products are emerging into the European and North American marketplaces. Consumer confidence in product is key in developing this market, and accurate labelling of content identity is an important component of this. We used DNA barcoding to assess the accuracy of insect food products sold in the UK.

Methods

We purchased insects sold for human consumption from online retailers in the UK and compared the identity of the material ascertained from DNA barcoding to that stated on the product packaging. To this end, the COI sequence of mitochondrial DNA was amplified and sequenced, and compared the sequences produced to reference sequences in NCBI and the Barcode of Life Data System (BOLD).

Results

The barcode identity of all insects that were farmed was consistent with the packaging label. In contrast, disparity between barcode identity and package contents was revealed in two cases of foraged material (mopane worm and winged termites). One case of very broad family-level description was also highlighted, where material described as grasshopper was identified as Locusta migratoria from DNA barcode.

Conclusion

Overall these data indicate the need to establish tight protocols to validate product identity in this developing market. Maintaining biosafety and consumer confidence rely on accurate and consistent product labelling that provides a clear chain of information from producer to consumer.

Nutritional value, protein and peptide composition of edible cricket powders

There are various indicators, including FAO and EU sources, that edible insects could become one of the solutions to the problem of global food supply. This report was aimed at improving the knowledge on powdered crickets (Acheta domesticus). The analyses of the basic nutritional composition revealed that cricket powders were rich in protein (42.0-45.8% of dry matter) and fat (23.6-29.1% of dry matter). In terms of mineral content, CPs were rich in Ca, Mg and Fe. Most of all, the levels of Cu, Mn and Zn were especially high (2.33-4.51, 4.1-12.5, 12.8-21.8 mg/100 g of dry matter, respectively). Furthermore, the analyses into the proteins indicated that the cricket powders were treated with high temperatures and allowed the determination of four cricket-specific peptides that showed sufficient thermostability to serve as markers for authentication.

Development of a fast real-time PCR assay based on TaqMan probe for identification of edible rice grasshopper (Oxya chinensis) in processed food products

Interest in using insects as an alternative source of food for humans is increasing. However, few analytical methods provide accurate information about the presence of insect species in processed foods. In this study, we developed a fast real-time PCR assay based on a TaqMan probe that can be performed within 40 min to detect edible rice grasshopper in commercial food products. A rice grasshopper-specific primer pair and probe targeting the cytochrome c oxidase subunit 1 (COI) gene were newly designed, having an amplicon size of 110 bp. The specificity of this primer pair and probe was verified using 19 insects and five crustaceans and no cross-reactivity was obtained against the non-target species. The absolute limit of detection (LOD) was 0.5 pg of rice grasshopper DNA, and as low as 0.1% of rice grasshopper was detected in raw, heat-treated, and autoclaved binary insect mixtures. To evaluate the effect of food matrix, binary mixtures containing rice grasshopper in wheat were used additionally, and at least 0.1% of target species was detected using this assay. The applicability of this assay was confirmed using nine commercial food samples labeled as containing rice grasshopper or locust. The fast real-time PCR developed in this study is a specific and sensitive method for identifying edible rice grasshopper in various food samples.