Nutritional Properties of Selected Edible Insects ^†

Abstract

This study aimed to determine the nutritional properties of selected edible insects as a potential future food. A total of eight species of edible insects, including the dubia roach (Blaptica dubia), super worm (Zophobas morio) larvae, locust (Locusta migratoria), silkworm (Bombyx mori) pupae, house cricket (Acheta domesticus), sago palm weevil (Rhynchophorus ferrugineus) larvae, black soldier fly (Hermetia illucens) larvae, and grasshopper (Oxya Yezoensis) have been obtained and analyzed for their macronutrient contents. Results showed that grasshopper (68.18 g/100 g) has the highest protein content, which is comparable to conventional animal meats. This indicates that the edible insect is a valuable alternative protein and provides essential amino acids. Thus, some edible insects could serve as a source of sustainable nutrients for daily requirements and mitigating food insecurity in the future.

1. Introduction

The global population is projected to reach 9.8 billion by 2050, and almost 1 billion individuals are suffering from chronic hunger globally [1,2]. There is an urgent need to have a sustainable food solution. Food production must increase by 60% to meet the demand, and the animal protein sources must increase by 70 to 80% [3]. However, the scarcity of arable land and inefficiencies in current food systems necessitate a reassessment of dietary habits and food production methods to minimize food waste and explore alternative food sources [2,4,5].

Entomophagy, or insect consumption, has recently gained global attention for its health, environmental, and economic advantages. By supplying distinctive, delectable, and nourishing foods to the populations in Latin America, Asia, Australia, and Africa [4], it has become a cultural heritage in these regions. About 2 billion people worldwide consume over 2000 species of edible insects, mostly in developing countries [6]. Most of these edible insect species are beetles and caterpillars; the remaining include bees, wasps, ants, grasshoppers, locusts, crickets, dragonflies, termites, and flies [7].

Edible insects are high in protein, fat, minerals, vitamins, and fiber, offering significant potential in addressing food insecurity [8]. In addition to other emergent food sources like lab-grown meat, microorganisms, and algae, insects are notable for their sustainability and usefulness [9]. Insects can be served raw, cooked, baked, or processed into powders for products like bread and biscuits [10,11,12].

Notably, insects are particularly efficient food sources due to their short lifespan, rapid reproduction rates, low carbon footprints, and minimal habitat or nutritional requirements. In addition, insect farming offers environmental advantages, such as the effective bioconversion of feed and lower demand for agricultural land compared to conventional animal farming [13,14]. Numerous insect farms have been constructed worldwide, particularly in Thailand and Southeast Asia [5]. There is a growing market for insect-based foods, as seen by the rising production of insect flour, cricket protein bars, and insect snacks [15]. Despite insects not being a common diet in the country, it is important to evaluate the potential of these insects as food sources for the near future. Therefore, this study aims to determine the main nutritional composition of the selected edible insects.

2. Materials and Methods

2.1. Insect Samples

The insect samples of sago palm weevil (SP) (Rhynchophorus ferrugineus) larvae, black soldier fly (BSF) (Hermetia illucens) larvae, cricket (CK) (Acheta domesticus) adult, dubia roach (DR) (Blaptica dubia) adult, grasshopper (GH) (Oxya yezoensis) adult, locust (LC) (Locusta migratoria) adult, silkworm (SW) (Bombyx mori) pupae, and superworm (SU) (Zophobas morio) larvae were obtained from JR Unique Foods, Udon Thani, Thailand (https://jrunique.com, accessed on 29 November 2024). All samples were obtained in the form of powder.

2.2. Nutritional Composition Analysis

The moisture content of the insect samples was determined using the Association of Official Analytical Chemists (AOAC) method 950.46 [16]. Five grams of insect powder was placed on a crucible and determined by the oven-drying method (105 °C for 24 h). The crude fat content was determined using the Soxhlet extraction according to method 934.01 [16]. The sample size was 2.0 g and extracted with petroleum ether for 4 h at a 6 drop/second drip rate. Crude protein content was determined by the Kjeldahl method 990.03 [16]. Ash content was obtained by incinerating 5 g of an insect powder sample in a muffle furnace at 550 °C for 24 h, according to method 920.153 [16]. The total carbohydrate content was calculated by subtracting the percentage of moisture, ash, lipid, and protein contents from 100 g samples [17]. The total energy value for the samples was calculated from the total crude protein, fat, and carbohydrate contents using Equation (1). All nutritional analyses are reported as mean values ± standard deviation of at least three replicates.

Total energy (kJ/100 g sample) = (total crude protein × 17) + (total crude fat × 37) + (carbohydrate × 17)

(1)

2.3. Statistical Analysis

All experiments were carried out in triplicate (n = 3), and the results were presented as mean ± standard deviations. Statistical analysis was performed using Statistical Package for the Social Science (SPSS) software version 29.0. The significant differences between the measurable variables were determined by one-way analysis of variance (ANOVA). The differences between the means at a 95% (p < 0.05) confidence level were considered statistically significant.

3. Results and Discussion

Nutritional Composition

The nutritional composition of the insect powder is shown in

Table 1. Proximate composition of selected insects in g/100 g (d.b.).

Nutrient Content (g/ 100 g)	SP	BSF	CK	DR	GH	LC	SW	SU
Moisture	4.52 ± 0.32 c	5.55 ± 0.06 c	3.46 ± 0.03 d	3.03 ± 0.16 ef	6.37 ± 0.10 b	6.52 ± 0.32 b	2.84 ± 0.04 f	11.20 ± 0.06 a
Crude fat	52.27 ± 0.19 a	27.6 ± 0.04 c	20.36 ± 0.42 e	27.70 ± 0.09 c	5.54 ± 0.23 f	5.54 ± 0.21 f	23.77 ± 0.59 d	35.87 ± 0.51 b
Crude protein	29.47 ± 0.21 g	39.35 ± 0.11 f	46.54 ± 0.08 e	47.90 ± 0.31 d	68.18 ± 0.45 a	66.45 ± 0.22 b	58.41 ± 0.13 c	39.09 ± 0.34 f
Ash	5.38 ± 0.15 a	5.19 ± 0.43 a	3.46 ± 0.03 b	5.25 ± 0.63 a	4.65 ± 0.23 a	4.88 ± 0.20 a	4.65 ± 0.72 a	4.70 ± 0.67 a
Carbohydrate	8.76 ± 0.64 e	23.56 ± 0.60 b	27.13 ± 0.58 a	16.63 ± 0.70 c	16.28 ± 0.16 c	17.76 ± 0.78 c	10.63 ± 0.86 d	10.29 ± 0.34 de
Energy (kcal/100 g)	637.27 ± 0.85 a	551.09 ± 6.56 b	483.94 ± 1.91 e	512.53 ± 2.70 c	394.03 ± 1.45 f	393.10 ± 1.36 f	495.58 ± 5.03 d	290.58 ± 4.20 g

Values are reported as mean ± standard deviation (n = 3). Different letters of the mean values indicate significant differences at p < 0.05. SP: Sago palm weevil; BSF: Black soldier fly; CK: Cricket; DR: Dubia roach; GH: Grasshopper; LC: Locust; SW: Silkworm; SU: Superworm.

. There were significant differences (p < 0.05) between the samples for all nutritional contents. The moisture content of the insect powder was determined at below 5 g/100 g (d.b.) since they were freeze-dried and stored in hermetically sealed packaging. This helps to maintain their low water activity and extend the shelf life [5]. Among the samples, DR had the lowest moisture content (3.03 g/100 g), while SU had the highest (11.20 g/100 g). The moisture content of BSF (5.55 g/100 g) and CK (3.46 g/100 g) was slightly lower than the values reported by Kamau et al. [18], where dried cricket and black soldier fly larvae powders were 4.52 g/100 g and 6.41 g/100 g, respectively. Results showed that edible insects with significantly lower moisture content often have a higher fat content. The difference in moisture content may be attributed to the insect species, developmental stages and the dehydration method applied in the preparation of powders. The SP powder in this study had a moisture content of 4.52 g/100 g. SP had lower protein and higher fat content, which indicates that the SP powder likely had fewer hydrophilic sites, contributing to its moisture retention characteristics [18].

The crude fat content of the insect powders varies significantly (p < 0.05) between species. The crude fat content of SP is the highest (52.27 g/100 g), while LC has the lowest (5.54 g/100 g). The difference in crude fat content of Coleoptera (sago palm weevil larvae) and Orthoptera (locust adult and grasshopper adult) is influenced by a combination of factors, including species-specific physiology, diet, environmental conditions, and metamorphic stages [8]. Supporting this observation, the larvae and pupae (e.g., SP, BSF, SW, SU) had higher fat content in this study. Additionally, the fat content of SU (35.87 g/100 g) is consistent with the findings by Perez-Santaescolastica et al. [19]. In addition to being a main source of energy, the fats of the edible insects provide our body with essential fatty acids that play an important role in maintaining human health. Studies have shown that insects have a fatty acid composition similar to that of poultry and fish but are richer in unsaturated fatty acids, particularly polyunsaturated fatty acids [19,20].

The GH, LC, and SW powders exhibited significantly high crude protein contents of 68.18, 66.45, and 58.41 g/100 g (d.b.), respectively. These findings align with Hăbeanu et al. [20], where SW powder contained 55 g/100 g of protein. Compared to the Recommended Nutrient Intake (RNI) for adults (61 g/day for males, 52 g/day for females), these protein levels demonstrate that insect powders can serve as protein sources. Protein is composed of more than 20 amino acids, but eight of them cannot be synthesized by the body and must be obtained externally to meet nutritional requirements. Furthermore, the protein content of these insect powders is higher than the conventional animal proteins such as chicken (13.3–18.3 g/100 g), beef (22.6 g/100 g), and fresh milk (3.2 g/100 g) [21]. Protein is an essential component of life and is highly sought after by humans. It plays important roles in the immune response and antibodies for the immune function, and the formation of enzymes for the biochemical reactions in metabolic pathways. The edible insects reported in this study may offer an affordable source of protein, especially for low-income communities, and be used as an ingredient for product development.

The ash content of targeted insects shows significant differences, indicating that the elements in mineral profiling would vary distinctly. The ash content in all insect powders is found below 5.00 g/100 g (d.b.) except for SP (5.38 g/100 g d.b.), BSF (5.19 g/100 g d.b.), and DR (5.25 g/100 g d.b.). The ash content is below 5.00/100 g on a dry weight basis. An elevated ash content corresponds to a more significant presence of mineral elements beneficial for human health. Crickets exhibit a higher ash content than goat, broiler, and pork meat [22]. A high level of ash content in insect powders indicate that they are a good source of minerals. The ash contents of the samples varied due to differences in location, diet, and season in which the insects are reared and harvested [23]. The addition of edible insect powder in food products could potentially enhance the mineral content of the foods to meet the daily requirements.

The carbohydrate content ranged from 8.76 to 27.13 g/100 g (d.b.) across all samples. The two edible insect powders (CK and BSF) showed a significantly higher (p < 0.05) carbohydrate content as compared to other insect samples, determined at 27.13% and 23.56%, respectively. However, sample SP has the lowest observed carbohydrate content among the insect species studied. A previous study reported that the carbohydrate levels in edible crickets ranged from 2.5 to 47.2 g/100 g (d.b.), attributed to the diets of the insects [22]. Carbohydrates are an energy source in the diet that contributes to the overall caloric intake [24]. In addition to being an energy source, insect-derived carbohydrates (chitin) exhibit functional properties such as prebiotic potential and antimicrobial, antiviral, and anti-fungal activities. However, they are occasionally classified as anti-nutritional factors due to their non-digestible fiber content [25].

The energy content per 100 g of the studied insects varies significantly, indicating that different insect species offer varying levels of energy. Energy is primarily derived from carbohydrates, proteins, and fats in food. Since edible insects are rich in these macronutrients, they provide a higher energy content. No significant differences (p > 0.05) were observed for GH (394.03 kcal/100 g) and LC (393.10 kcal/100 g), probably due to the same metamorphic stage and order (Orthoptera), as well as their similar nutritional composition. SP is found to provide the highest energy content, with 607 kcal energy per 100 g. This might be mainly due to the high fat content of the insect, since fat contributed most significantly to energy. On the other hand, the insect sample that generated the lowest energy per 100 g consumption is SU.

Meanwhile, the energy provided by other edible insects typically ranges from 393.10 kcal/100 g to 551.09 kcal/100 g. For a diet requiring 2000 kcal, 100 g of edible insects per day covered at least 15% of the daily 2000 kcal diet. All studied edible insects were found to have a higher energy content than the chicken drumstick (125 kcal/100 g), beef sirloin (112 kcal/100 g), and pork shoulder (13.2 kcal/100 g) [23]. Nevertheless, the energy value of edible insects depends on their composition, mainly on the fat content. Larvae or pupae are usually richer in energy compared to adults [26].

Despite growing interest in utilizing insects for their nutritional benefits, several challenges hinder widespread acceptance. An emerging trend involves incorporating insect powder to boost the nutritional value of various food products, such as protein-rich snacks, energy bars, pasta, and baked goods [27]. A major concern is the potential for allergic reactions among individuals sensitive to crustaceans and dust mites due to shared allergens like tropomyosin and arginine kinase [28,29]. Psychological barriers, including food neophobia and disgust, also affect consumer willingness to engage in entomophagy. Research shows that individuals without prior insect consumption experience exhibit stronger aversions, emphasizing the need for sensory exposure and cultural acceptance [30]. Additionally, regulatory challenges and safety concerns regarding microbiological and chemical contaminants in insect-based products require further research and standardization [28,30]. Addressing these issues through improved processing, clear labeling, and consumer education will be crucial in promoting insects as a sustainable protein source.

4. Conclusions

In the present study, it was found that the dubia roach (Blaptica dubia) adult, locust (Locusta migratoria) adult, and superworm (Zophobas morio) larvae are good sources of protein and fats, which are comparable to conventional meats. Among these, grasshoppers (Oxya Yezoensis) emerge as the most promising option in terms of nutritional value. Insects could potentially be used for global food security issues. However, further study shall address the safety concerns, such as potential toxicity and allergenicity, and understand the functional properties of edible insects for broader applications.