Low protein digestibility-corrected amino acid score and net nitrogen-to-protein conversion factor value of edible insects.

The amount of chitin, a nitrogen-containing dietary fiber, in edible insects can mislead the exact nitrogen-to-protein conversion factor (NPF) and true protein content. We determined the amino acid score (AAS), protein digestibility-corrected AAS (PDCAAS), chitin content, and net NPF of five edible insects. Additionally, the effect of the amino acid composition of migratory locust on rat growth were investigated. The AAS of the insects were ranged from 63 to 94. The chitin contents were ranged from 1.6 g/100 g to 10.7 g/100 g. The PDCAAS, calculated by AAS and gut-intestinal digestibility, ranged from 44 to 81, which was lower than casein (97). The net NPF ranged from 4.93 to 5.76, which were lower than the conventional value. Dietary migratory locust, whose PDCAAS was the lowest, decreased growth and altered lipid metabolism. Therefore, a lower PDCAAS and overestimation of net NPF of insects can affect the true protein calculations and growth.

The Preparation and Physiochemical Characterization of Tenebrio molitor Chitin Using Alcalase.

Chitin is mostly produced from crustaceans, but it is difficult to supply raw materials due to marine pollution, and the commonly used chemical chitin extraction method is not environmentally friendly. Therefore, this study aims to establish a chitin extraction process using enzymes and to develop edible insect-derived chitin as an eco-friendly new material. The response surface methodology (RSM) was used to determine the optimal conditions for enzymatic hydrolysis. The optimal conditions for enzymatic hydrolysis by RSM were determined to be the substrate concentration (7.5%), enzyme concentration (80 µL/g), and reaction time (24 h). The solubility and DDA of the mealworm chitosan were 45% and 37%, respectively, and those of the commercial chitosan were 61% and 57%, respectively. In regard to the thermodynamic properties, the exothermic peak of mealworm chitin was similar to that of commercial chitin. In the FT-IR spectrum, a band was observed in mealworm chitin corresponding to the C=O of the NHCOCH3 group at 1645 cm-1, but this band showed low-intensity C=O in the mealworm chitosan due to deacetylation. Collectively, mealworm chitosan shows almost similar physical and chemical properties to commercial chitosan. Therefore, it is shown that an eco-friendly process can be introduced into chitosan production by using enzyme-extracted mealworms for chitin/chitosan production.

Bioactive Peptide Discovery from Edible Insects for Potential Applications in Human Health and Agriculture.

In the past decade, there has been fast-growing interest among researchers to discover bioactive peptides from edible insects and to evaluate their potential applications in the management of human, livestock, and plant health. This review summarizes current knowledge of insect-derived peptides and their potential role in tackling human health issues and solving agriculture problems by protecting crops and livestock against their pathogens. Numerous bioactive peptides have been identified from edible insect species, including peptides that were enzymatically liberated from insect proteins and endogenous peptides that occur naturally in insects. The peptides exhibited diverse bioactivities, encompassing antioxidant, anti-angiotensin-converting enzyme, anti-dipeptidyl peptidase-IV, anti-glucosidase, anti-lipase, anti-lipoxygenase, anti-cyclooxygenase, anti-obesity, and hepatoprotective activities. Such findings point to their potential contribution to solving human health problems related to inflammation, free radical damage, diabetes, hypertension, and liver damage, among others. Although most of the experiments were performed in vitro, evidence for the in vivo efficacy of some peptides is emerging. Evidence of the protective effects of insect-derived endogenous antimicrobial peptides in combating farm animal and plant pathogens is available. The ability of insect-derived endogenous neuropeptides to protect plants against herbivorous insects has been demonstrated as well. Nevertheless, the potency of peptides identified from insect protein hydrolysates in modulating livestock and plant health remains a knowledge gap to be filled.

Edible insects prevent changes to brain monoamine profiles from malnourishment in weaned rats.

Background: Childhood malnutrition can have devastating consequences on health, behavior, and cognition. Edible insects are sustainable low cost high protein and iron nutritious foods that can prevent malnutrition. However, it is unclear whether insect-based diets may help prevent changes to brain neurochemistry associated with malnutrition.Materials and Methods: Weanling male Sprague-Dawley rats were malnourished by feeding a low protein-iron diet (LPI, 5% protein and ∼2 ppm Fe) for 3 weeks or nourished by feeding a sufficient protein-iron diet (SPI, 15% protein 20 ppm FeSO4) for the duration of the study. Following 3 weeks of LPI diet, three subsets of the malnourished rats were placed on repletion diets supplemented with cricket, palm weevil larvae, or the SPI diet for 2 weeks, while the remaining rats continued the LPI diet for an additional 2 weeks. Monoamine-related neurochemicals (e.g. serotonin (5-HT), dopamine (DA), norepinephrine) and select monoamine metabolites were measured in the hypothalamus, hippocampus, striatum, and prefrontal cortex using Ultra High-Performance Liquid Chromatography.Results: Five weeks of LPI diets disrupted brain monoamines, most notable in the hypothalamus. Two weeks supplementation with cricket and palm weevil larvae diets prevented changes to measures of 5-HT and DA turnover in the hippocampus and hypothalamus. Moreover, these insect diets prevented the malnutrition-induced imbalance of 5-HT and DA metabolites in the hippocampus, striatum, and hypothalamus.Conclusion: Edible insects such as cricket and palm weevil larvae could be sustainable nutrition intervention to prevent behavioral and cognitive impairment associated abnormal brain monoamine activities that results from early life malnutrition.

Physico-chemical and colloidal properties of protein extracted from black soldier fly (Hermetia illucens) larvae.

The black soldier fly larvae (BSFL), Hermetia illucens (Linnaeus), has been largely utilized for animal feed. Due to its interesting composition, BSFL has great potential to be further implemented in the human diet. Herein we compared the flour and protein extract composition based on their moisture, ash, amino acids, mineral, and protein content. To have wide knowledge on protein profile and behavior, SDS-page electrophoresis, Fourier-transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC) were used to give information about protein structure and thermal stability, respectively. The flour and protein extract contained respectively 37.3% and 61.1% of protein. DSC graph reported a glass transition temperature around 30 °C, recognizable by a shift in the curve, and an endothermic peak for solid melting at around 200 °C. FTIR analysis showed the main amide bands (A, B, I, II, III) for the flour and protein extract. The foam properties of BSFL protein extract were explored under different temperatures treatment, and the best foam stability was reached at 85 °C with 15 min of treatment. The data highlight the promising techno-functional properties of BSFL protein extract, and that the nutritional composition might be suitable for further use of BSFL as food fortification system.

Effects of Edible Insect Tenebrio molitor Larva Fermentation Extract as a Substitute Protein on Hepatosteatogenesis and Proteomic Changes in Obese Mice Induced by High-Fat Diet.

Mealworms (Tenebrio molitor larva) are an edible insect and a protein-rich food; however, research on mealworms as a substitute protein is insufficient. In this study, mealworm fermentation extract (TMP) was assessed as a replacement for soy protein (SP) in a control diet (CON) or a high-fat diet (HFD) of mice for 12 weeks. TMP substitution reduced body weight, body weight gain, body fat mass (perirenal and mesenteric), fat size, glucose intolerance, and insulin resistance compared to the HFD-SP group. TMP alleviated hepatic steatosis (lipid contents and lipid droplets) in high-fat-fed mice and down-regulated the PPARγ, CD36, and DGAT2 gene levels. Proteomic analysis showed that a HFD for 12 weeks up-regulated 20 proteins and down-regulated 17 proteins in mice fed SP. On the other hand, TMP reversed the protein profiles. TMP significantly down-regulated KHK, GLO1, ATP5H, SOD, and DDAH1 and up-regulated DLD, Mup1, CPS1, Ces3b, PDI, and HYOU1 compared to the HFD-SP group. These proteins are involved in the glucose, lipid, and amino acid metabolism, as well as in oxidative stress and endoplasmic reticulum stress. Thus, substituting SP for TMP helped improve HFD-induced obesity, steatosis, and insulin resistance in mice. These results suggest that TMP is a potential substitute for commonly used protein sources.

Nutritional Composition of Edible Insects Consumed in Africa: A Systematic Review.

Edible insects are an important protein rich natural resource that can contribute to resilient food security. Edible insects not only play an important role in traditional diets, but are also an excellent source of protein in traditional dishes in Africa. We systematically searched Web-of-Science and Google Scholar from year 2000-2019 for studies on the consumption of insects and their nutritional composition in Africa, resulting in 98 eligible papers, listing 212 edible insect species from eight orders. These insects were rich in protein, fats, and fibre. The highest protein content was reported for Lepidoptera (range: 20-80%). Coleoptera had the highest carbohydrate content (7-54%), while Lepidoptera had the highest fat content (10-50%). Considering the excellent source of nutrition, and potential socio-economic benefits, from edible insects, they can contribute strongly to improved food security, and rural development in developing countries. In addition, edible insects can be used as a sustainable food source to combat food shortages in the future, for example, providing resilience during times of drought or other climate stressors.

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

Heat processing is commonly used to prepare edible insects for consumption. This study aimed at determining the effect of boiling and subsequent oven roasting on Ruspolia differens' nutrient composition, colour and odor compounds. Boiling leads to: a significant increase in protein and decrease in fat content on a dry matter basis; a minimal influence on its amino and fatty acids profile; a significant reduction in its ash content due to leaching of phosphorus, potassium and sodium; a significant increase in iron, zinc, copper, manganese and calcium content; and a fivefold reduction in the amount of vitamin B12. Roasting leads to a relative increase in the amount of calcium and trace mineral elements but doesn't affect other nutrients. Roasting results into a more uniform colour intensity when green and brown polymorphs are roasted together. Lipid oxidation is responsible for the colour and aroma of heat processed R. differens.

Dietary enrichment of edible insects with omega 3 fatty acids.

Edible insects are advocated as sustainable and healthy food and feed. However, commercially produced insects are often low in n-3 fatty acids and have suboptimal n-6/n-3 ratios. A certain amount and proportion of these FAs is required to optimize human health. Flaxseed oil consists primarily (57%) out of alpha-linolenic acid. An experiment was conducted to quantify the effect of flaxseed oil provision on fatty acid composition and to determine the quantity needed to attain a beneficial n-6/n-3 ratio. Three species were used in the experiment: house crickets (Acheta domesticus [L.]), lesser mealworms (Alphitobius diaperinus [Pfanzer]) and black soldier flies (Hermetia illucens [L.]). These were provided with either a control diet or a diet enriched with 1%, 2%, or 4% flaxseed oil during their larval/nymphal stage. Fatty acid profiles of diets and insects were determined via GC-MS. The three species had distinct fatty acid profiles on all four diets, but responded similarly to flaxseed oil addition. For each percent added to the diet, the alpha-linolenic acid content of the insects increased by 2.3%-2.7%. Four percent addition increased the n-3 fatty acid content 10-20 fold in the three species and thereby strongly decreased n-6/n-3 ratios from 18-36 to 0.8-2.4. A ratio below 5 is considered optimal for human health and was achieved by 2% flaxseed oil inclusion for house crickets and lesser mealworms, and at 1% inclusion for black soldier flies. Adding a source of n-3 fatty acids to insect diets can thus improve the nutritional quality of insects.

From entomophagy to entomotherapy.

Insects are the most diverse group of organisms with one million species that account for 80% of the world's species. Particularly in East Asia, edible insects serve as a source of nutrients. Among these, silkworms and honeybees are well-known sources of food and have been used for the treatment of a large number of human disorders. This review focuses on the utilization of insects as food (entomophagy) as well as for their pharmacological properties (entomotherapy) that have been tested in vitro as well as in vivo.

Iron-polyphenol complexes cause blackening upon grinding Hermetia illucens (black soldier fly) larvae.

Insects are a promising alternative protein source. One of the bottlenecks in applying insects in food is the fast darkening initiated during grinding. Besides enzymatic browning, non-enzymatic factors can cause off-colour formation, which differs between species. This study investigates the impact of iron, phenoloxidase, and polyphenols on off-colour formation in insect larvae. Hermetia illucens showed a blackish colour, whereas Tenebrio molitor turned brown and Alphitobius diaperinus remained the lightest. This off-colour formation appeared correlated with the iron content in the larvae, which was 61 ± 9.71, 54 ± 1.72 and 221 ± 6.07 mg/kg dw for T. molitor, A. diaperinus and H. illucens, respectively. In model systems, the formation of iron-L-3,4-dihydroxyphenylalanine (L-DOPA) bis- and tris-complexes were evidenced by direct injection into ESI-TOF-MS, based on their charges combined with iron isotope patterns. The reversibility of the binding of iron to phenolics, and thereby loss of blackening, was confirmed by EDTA addition. Besides complex formation, oxidation of L-DOPA by redox reactions with iron occurred mainly at low pH, whereas auto-oxidation of L-DOPA mainly occurred at pH 10. Tyrosinase (i.e. phenoloxidase) activity did not change complex formation. The similarity in off-colour formation between the model system and insects indicated an important role for iron-phenolic complexation in blackening.