Effect of heat processing on the nutrient composition, colour, and volatile odour compounds of the long-horned grasshopper Ruspolia differens serville

Effect of fortifying sorghum and wheat with Longhorn grasshopper (Ruspolia differens) powder on nutritional composition and consumer acceptability of biscuits

This study aimed at improving the nutrient composition and protein quality of biscuits made from sorghum and wheat through fortification with Longhorn Ruspolia differens powder (RDP) for use as a supplementary food targeting children vulnerable to protein-energy malnutrition (PEM). Ten biscuit formulations were prepared by replacing a part of wheat and sorghum-wheat flours with 5, 15, 20, and 40% RDP. To establish the nutrient content of biscuits, proximate and mineral compositions were determined. The amino acid composition, reactive lysine and in vitro protein digestibility were determined for protein quality. Compositing wheat or wheat-sorghum biscuits with RDP increased the protein, fat, ash, and crude fiber by percentages as high as 118, 37, 133, and 573%, respectively. Mineral content increased with, iron, zinc, and potassium as high as 161, 219, and 169%, respectively. The lysine, reactive lysine and in vitro protein digestibility of the fortified biscuits increased significantly, relative to the 100% cereal biscuits. Fortification with RDP significantly improved the amino acid content of the biscuits but had a marginal effect on improvement of the lysine score and did not meet the reference pattern for children aged 3-10 years. The Protein Digestibility Corrected Amino Acid Score (PDCAAS) of wheat-sorghum and wheat biscuits improved by 6% to 47% and 2% to 33%, respectively, compared to the control biscuits. The fortified biscuits were liked by the consumers. The RDP-fortified biscuits have the potential to alleviate PME in developing countries.

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.

Effect of cooking methods on nutritional value and microbial safety of edible rhinoceros beetle grubs (Oryctes sp.)

Although edible rhinoceros beetle (Oryctes sp.) larvae are popularly consumed in many countries worldwide, they are prepared using different methods such as boiling, roasting, toasting, and deep-frying, whose effect on nutritional value and microbial safety is scarcely known. Here we investigated the effect of these methods on the nutritional value and microbial safety of Oryctes sp. larvae. Our hypothesis was that cooking the grubs using the four methods had no effect on their nutritional content and microbial loads and diversity. The grubs were analyzed for proximate composition, and fatty and amino acid profiles using standard chemical procedures; and microbial safety using standard culturing procedures. Deep-frying reduced protein and carbohydrate content, but elevated fat content. Boiling lowered ash content, but increased fibre and carbohydrate composition. Roasting and toasting increased protein and ash contents, respectively. Forty fatty acids were detected in the larvae, of which levels of only five were not significantly affected by cooking method, while the levels of the others were differentially affected by the different cooking methods. Amino acid profiles and levels were largely comparable across treatments, but lysine and arginine were higher in all cooked grubs than raw form. All the cooking methods eliminated Enterobacteriaceae, Shigella sp. and Campylobacter sp. from the grubs. Except boiling, all methods reduced total viable count to safe levels. Salmonella sp. were only eliminated by toasting and roasting; while boiling promoted growth of yeast and moulds. Staphylococcus aureus levels exceeded safety limits in all the cooking methods. These findings offer guidance on the type of method to use in preparing the grubs for desired nutritional and safety outcomes.

Consumption of edible insects and insect-based foods: A systematic review of sensory properties and evoked emotional response

Low consumer acceptance of edible insects and insect-based products is one of the main barriers to the successful implementation of entomophagy in Western countries. This rejection is mainly caused by consumers' negative emotional responses, psychological/personality traits, and attitudes toward food choices. However, as the role of intrinsic product characteristics on such food choices has not been adequately studied, a systematic review was conducted following the PRISMA method, to analyze studies that have assessed hedonic evaluations, sensory profiling, or emotional responses to edible insects or insect-based products. The majority of studies performed with whole insects and insect flour highlight that insect-based products are more negatively evaluated than control products. Although the sensory properties of insects are affected by species and processing conditions, they are generally negative across sensory dimensions. In particular, insects and insect-based products are generally associated with odor and flavor/taste attributes that are related to old/spoiled food. These negative attributes can be linked to the fat fraction of edible insects, with insect oils being very negatively evaluated by consumers. On the other hand, defatted fractions and deodorized oils are not associated with these negative attributes, further supporting the hypothesis that the fat fraction is responsible for the negative odor and flavor/taste attributes. However, there is still a lack of studies assessing the sensory profile of edible insects and insect-based products, as well as consumers' emotional responses to their consumption. Future studies should focus on the effects of different processing conditions, products incorporating insect fractions (namely protein concentrates/isolates and defatted fractions), and evaluation by target consumer groups.

Evaluation of Roasting and Grilling Effects on Chemical Composition, Volatile Profiles, and Toxicity of Stink Bugs (Tessaratoma papillosa): Implications for Utilization as Functional Food Ingredients

The stink bug (Tessaratoma papillosa) is a highly popular edible insect in Thai traditional cuisine, but little research has investigated the effects of heat treatment on the quality of stink bugs. Therefore, we aimed to evaluate the effects of roasting and grilling on the chemical changes and volatile compounds of late nymph and adult stink bugs. In general, all treated samples showed increases in phenolic acid, tocopherols, and amino acid contents and a decrease in the content of fiber compared with raw stink bugs (p < 0.05). Cinnamic acid significantly increased by over 200% in late nymph insects and 30% in adult insects after roasting, whereas syringic acid decreased after cooking (p < 0.05). The most predominant volatile compound found in all samples was 5-methyl-octadecane and it decreased after cooking, while volatile alkane compounds increased after cooking. The processed sample extracts showed higher toxicity on oral cancer KB and cervical cancer Hela cells than on Vero cells. We have demonstrated that different cooking methods affected the chemical components which may result in quality attributes if stink bug is to be used as a functional ingredient/food. It may be helpful to improve the nutritional and functional values of stink bugs during deep processing.

Effects of drying on the nutritional, sensory and microbiological quality of edible stinkbug (Encosternumdelgorguei)

Entomophagy has recently gained attention as a potential solution to the problems of food and nutritional security. One example is the consumption of edible stinkbug. Different drying techniques may affect the nutritional, microbiological and sensory properties of the edible stinkbugs. Thus, the study assessed the effects of toasting, microwave, oven and sun drying on the nutritional composition, microbiological quality and sensory attributes of processed edible stinkbugs. Drying significantly (p < 0.05) increased the crude protein and fat content of the edible stink bugs with the highest values being recorded for the toasted samples (66.65 & 37.17% respectively). Highest Ca, K, Zn, Mg, Fe and P values were recorded after microwave drying. Reduction of 2.94 and 2.99 log cycles of the total viable count (TVC) was observed in oven and microwave dried edible stinkbugs. Toasting and microwave drying eliminated the yeasts and moulds, Enterobacteriaceae and lactic acid bacteria (LAB) in edible stinkbugs. The appearance, aroma, taste, texture and overall acceptability scores were in the same order for toasted > oven dried > microwave dried > sun dried edible stinkbugs. Toasting, oven and microwave drying can be used for processing of edible stinkbugs.

Aroma characterization and consumer acceptance of four cookie products enriched with insect (Ruspolia differens) meal

This research aims to advance knowledge on the impact of four processing methods on volatile compounds from insect-based baked products (cookies) to provide insights on consumer acceptance. Samples were exposed to double step enzyme digestive test, volatiles characterized through headspace analysis, while semi-trained panelists were recruited for the sensory test. Blanched and boiled samples of R. differens had considerably higher digestibility (83.42% and 81.61%, respectively) (p < 0.05) than toasted and deep-fried samples. Insect-based cookie products integrated with blanched and boiled R. differens meal expressed higher digestibility (80.41% and 78.73%, respectively) that was comparable to that of commercial cookie products (control cookies-CTRC with 88.22%). Key volatile compounds common between the various cookie products included, nonanal, octanal, methyl-pyrazine, hexanal, tetradecane, 2-pentylfuran, 2-heptanone, 2E-octenal, 2E-heptenal and dodecane. Among the volatile compounds, pleasant aromas observed were 2E,4E-dodecadienal, pentanal, octanal, methyl pyrazine, furfurals, benzaldehyde, and 2-pentyl furan, which were more pronounced in cookies fortified with boiled, toasted and deep-fried R. differens meal. There was a greater resemblance of sensory characteristics between control cookies and those fortified with deep-fried R. differens. These findings underscore the significant influence of aroma compounds on consumer acceptability and preference for insect-based baked food products, which allows for future process-modification of innate aromas of insect-based meals to produce high-valued pleasant consumer driven market products.

Variability in nutrient composition of the edible long-horned grasshopper (Ruspolia differens) in Uganda and its potential in alleviating food insecurity

Ruspolia differens Serville (Orthoptera: Tettigonidae) is a highly nutritious and luxurious insect delicacy that is consumed as a food source in many African countries. However, the nutrient profile of R. differens in different geographical regions have received limited research interest. Here, we provide comprehensive evidence of geographical impact on the nutrient profile of R. differens and its potential to meet the recommended dietary intake of the population. Our results demonstrated that proximate composition, fatty acids, amino acids, minerals, vitamins, and flavonoid contents of R. differens collected from five districts in Uganda varied considerably. The crude protein (28-45%), crude fat (41-54%), and energy (582-644 Kj/100 g) contents of R. differens exceed that reported from animal origins. The highest crude protein, crude fat, and carbohydrate contents of R. differens were recorded in Kabale, Masaka, and Kampala, respectively. A total of 37 fatty acids were identified with linoleic acid (omega-6 fatty acid) being the most abundant polyunsaturated fatty acid in R. differens from Kabale, Masaka, and Mbarara. All essential amino acids were recorded in R. differens, particularly histidine with values exceeding the daily requirement for adults. Mineral and vitamin content differed significantly across the five districts. The highest quantity of flavonoids was recorded in R. differens from Hoima (484 mg/100 g). Our findings revealed that R. differens could be considered as functional food ingredients capable of supplying essential macro- and micronutrients that are critical in curbing the rising food insecurity and malnutrition in the regions.

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

Comparing the aromatic profile of seven unheated edible insect species

Insects and insect-based products have gained increasing interest as human food because of their many technological, nutritional and environmental advantages, but they are still rejected by many Western consumers. Analytical knowledge of flavour compounds could contribute to enhancing product attractiveness to consumers. Therefore, the goal of this study was to examine the volatile compound profiles of 7 unheated insects: Zophobas morio (ZM), Tenebrio molitor (TM), Locusta migratoria (LM), Galleria mellonella (GM), Blaptica dubia (BD), Alphitobius diaperinus (ALD) and Acheta domesticus (ACD). A total of 67 compounds were identified. Carboxylic acids were predominant in ALD, BD, GM, TM and ZM, while ketones were the major family in ACD and linear hydrocarbons in LM. ZM contained the highest number of unpleasant odour compounds, including indole, also present in BD and GM, which is characterised by a low detection threshold.

Nutritional Quality of Four Novel Porridge Products Blended with Edible Cricket (Scapsipedus icipe) Meal for Food

Currently, no data exist on the utilization of the newly described cricket species (Scapsipedus icipe) meal as additive in food products, though they have high protein (57%) with 88% total digestibility as well as a variety of essential amino acids. This article presents the first report on the effects of processing techniques and the inclusion of cricket meal (CM) on the nutrient and antinutrient properties of four porridge products compared to a popularly consumed commercial porridge flour (CPF). Porridge enriched with CM had significantly higher protein (2-folds), crude fat (3.4-4-folds), and energy (1.1-1.2-folds) levels than the CPF. Fermented cereal porridge fortified with CM had all three types of omega-3 fatty acids compared to the others. The vitamin content across the different porridge products varied considerably. Germinated cereal porridge with CM had significantly higher iron content (19.5 mg/100 g). Zinc levels ranged from 3.1-3.7 mg/100 g across the various treatments. Total flavonoid content varied significantly in the different porridge products. The phytic acid degradation in germinated and fermented porridge products with CM was 67% and 33%, respectively. Thus, the fortification of porridge products with cricket and indigenous vegetable grain powder could be considered an appropriate preventive approach against malnutrition and to reduce incidences in many low-and middle-income countries.

Chemical Composition, Nutrient Quality and Acceptability of Edible Insects Are Affected by Species, Developmental Stage, Gender, Diet, and Processing Method

Edible insects have been considered as either nutritious food itemsper se, or as wholesome ingredients to various dishes and components of traditional subsistence. Protein, fat, mineral and vitamin contents in insects generally satisfy the requirements of healthy food, although there is considerable variation associated with insect species, collection site, processing method, insect life stage, rearing technology and insect feed. A comparison of available data(based on dry weight) showed that processing can improve the nutrient content, taste, flavour, appearance and palatability of insects, but that there are additional factors, which can impact the content and composition of insect species that have been recommended for consumption by humans. This review focuses on factors that have received little attention in connection with the task to improve acceptability or choice of edible insects and suggests ways to guarantee food security in countries where deficiencies in protein and minerals are an acute and perpetual problem. This review is meant to assist the food industry to select the most suitable species as well as processing methods for insect-based food products.

Impact of Processing Technology on Macro- and Micronutrient Profile of Protein-Enriched Products from Fish Backbones

Impacts of processing technology (mechanical separation and pH-shift processing) on protein recovery from salmon, herring and cod backbones and the content of macro- and micronutrients in the recovered protein enriched products were investigated. Mechanical separation led to higher protein recovery compared with the pH-shift process and using both techniques, recovery ranked the species as herring > salmon > cod. However, the pH-shift process up-concentrated protein from herring and salmon backbones more efficiently than mechanical separation by removing more fat and ash. This consequently reduced n-3 PUFA and vitamin D content in their protein isolates compared with the backbones and mechanically separated meat (MSM). Cod protein isolate, however, contained higher levels of these nutrients compared with MSM. Mechanical separation concentrated vitamins E and C in salmon MSM but not for cod and herring. Opposite, pH-shift processing reduced levels of these two vitamins for cod and herring backbones, while vitamins D and C were reduced for salmon. For minerals, selenium, calcium, magnesium, and potassium were lower in protein isolates than MSM, while copper, zinc, iron and manganese were similar or higher. Overall, there is a major potential for upcycling of fish backbones to food ingredients, but processing technology should be carefully balanced against the desired nutrient profile and final application area.

Chemistry and Sensory Characterization of a Bakery Product Prepared with Oils from African Edible Insects

Globally, there is growing interest to integrate insect-derived ingredients into food products. Knowledge of consumer perception to these food products is growing rapidly in the literature, but similar knowledge on the use of oils from African edible insects remains to be established. In this study, we (1) compared the chemistry of the oils from two commonly consumed grasshoppers, the desert locust Schistocerca gregaria and the African bush-cricket Ruspolia differens with those of olive and sesame oils; (2) compared the proximate composition of a baked product (cookie) prepared from the oils; (3) identified the potential volatiles and fatty acids contributing to the aroma and taste; and (4) examined acceptance and willingness to pay (WTP) for the baked product among consumers with no previous experience of entomophagy. Our results showed that the insect oils were compositionally richer in omega-3 fatty acids, flavonoids, and vitamin E than the plant oils. Proximate analysis and volatile chemistry revealed that differences in aroma and taste of the cookies were associated with their sources of oils. Consumers' acceptance was high for cookies prepared with R. differens (95%) and sesame (89%) oils compared to those with olive and S. gregaria oils. Notably, cookies prepared with insect oils had more than 50% dislike in aroma and taste. Consumers' willingness to pay for cookies prepared with insect oils was 6-8 times higher than for cookies containing olive oil, but 3-4 times lower than cookies containing sesame oil. Our findings show that integrating edible insect oils into cookies, entices people to ''take the first step" in entomophagy by decreasing insect-based food products neophobia, thereby, contributing to consumers' acceptance of the baked products. However, future research should explore the use of refined or flavored insect oils for bakery products to reduce off-flavors that might have been perceived in the formulated food products.