The PWL were sorted and degutted by cutting off the edible insects’ black end (fecal part). It was then washed adequately in potable water and drained. Two grams of seasonings and a pinch of salt were added to 400 g of edible insects and stir-fried on low heat for 15 min. The stir-fried insects were set aside for further preparation.

The silkworm pupae were thoroughly sorted. The discolored (black) insects were removed, and the others that retained their natural brown color were further processed. About 400 g of the pupae were thoroughly washed, minimally salted, seasoned (2 g), and stir-fried on low heat for 15 min. After cooling, the insects were set aside for later use.

The conventional proteins (beef, chicken, and mackerel fish) were obtained in small cut sizes from the market. The beef, chicken, and fish were prepared separately. The fish was degutted, and the fins were removed. After thoroughly washing with potable water, each protein source (400 g) was prepped with 4 g seasonings, 4 g salt, 30 g of diced onions, and 30 mL of water. The meat, chicken, and fish were boiled for 10 min under medium heat and later stir-fried for 5 min under low heat.

Other ingredients: The outer layer of the carrot was scraped and then washed before grating. The grated carrots were then stir-fried in 20 mL of soya bean oil for 5 min and divided into five portions after cooling. The outer layer of the cabbage was removed and washed in a mild salt solution before shredding with a sharp knife into thin layers. The pepper sauce was prepared by blending tomatoes, habanero pepper, and onion bulbs (60 g). The resultant mixture was fried in 35 mL of soya bean oil with a pinch of salt and 4 g of seasoning cube for 15 min.

Each filling (Figure S1) was prepared by mixing 150 g shredded cabbage, 80 g stir-fried carrot, 70 g protein source (beef, fish, chicken, PWL or silkworm pupae), and 35 g pepper sauce. A total of five different fillings were then obtained.

The old-fashioned oat (285 g) was weighed in three batches into the cup of the grinder (1,500 W Euro Premium Domestic mixer/grinder, India) and 1,275 mL of potable water was used in blending in total. The grinding period took a total of 30 min until a smooth texture was obtained. The slurry was carefully transferred into a bowl, and 0.5 g of table salt was added with a little stir. The mixture was allowed to rest for 20 min. After resting, a full scoop of the batter was evenly spread into the pre-heated non-stick frying pan and heated on both sides for 4 min each. The resultant flatbread was 40 g in weight after cooling. The prepared fillings (20 g) (Figure S1) were then incorporated into different flatbreads and wrapped up to obtain the GF oat-based break wraps (Figure S2). Five wraps were obtained based on the protein sources (Table 1).

The AOAC [19] standard methods were employed to evaluate the proximate composition of the five breakfast wraps. Hexane was used for fat extraction using the Soxhlet method. The Kjeldahl method was employed to determine the nitrogen content of the samples. The nitrogen was converted to protein using 6.25 as the conversion factor. Crude fiber content was determined by the acid and alkali digestion of the samples. To obtain percentage ash, the samples were incinerated at 550°C in a muffle furnace (Carbolite, S33-6RB, Hope, England). The GF wraps were oven-dried until constant weights were obtained to obtain the moisture content. All analyses were replicated.

The nutritive elements of the breakfast wraps were determined using the AOAC methods [20]. One gram of the sample was digested with nitric/perchloric/sulphuric acid (9:2:1, v/v/v) and filtered. The obtained filtrate was made up to mark (5 mL) in a volumetric flask. Iron, calcium, zinc, magnesium, and selenium were determined using an Atomic Absorption Spectrophotometer. Phosphorus was determined using the Vanado-molybdate method. For sodium and potassium, a flame photometer (Sherwood Flame Photometer 410; Sherwood Scientific Ltd., Cambridge, UK) was used, and sodium chloride and potassium chloride were used as standards.

The AA profiles of the five wraps were determined using Applied Bio-systems PTH Amino Acid Analyzer following the procedure of AOAC [20]. A known sample was dried to constant weight, defatted using chloroform/methanol mixture of ratio 2:1 in a Soxhlet extraction apparatus for 15 h, hydrolyzed with 7 mL of 6 N HCl, evaporated in a rotary evaporator and loaded into the Amino Acid Analyzer. One hundred and 15 mg of the ground samples were then analyzed for nitrogen. Tryptophan in the wraps was determined as described by Yust et al. [25]. Samples were hydrolyzed with sodium hydroxide (4 M), dried, and defatted appropriately before hydrolysis. The hydrolyzed samples were evaporated in a rotary evaporator before the AA analysis using the analyzer. Protein indices such as total AA, total essential AA, total sulphur AA were calculated from the amino acid profile.

Samples were extracted using the Soxhlet extraction method [19]. Fifty milliliters of the extracted oil were esterified using 3.4 mL of 0.5 M KOH in dry methanol at 95°C for 5 min. Neutralization of the resultant mixture was done using 0.7 M HCl. Approximately 3 mL of boron trifluoride (14%) in methanol was added. To achieve a total methylation process, the concentration of the mixture was carried out at 90°C for 5 min. Re-distilled normal hexane was then used to extract the fatty acid methyl esters. For the gas chromatography analysis, the content was concentrated to 1 mL and 1 g/L was injected into the injection port of the GC coupled with a flame ionization detector (FID) (Buck Scientific 91). The fatty acid analysis was carried out under the following conditions: column type: RESTEK 10 m MXT-2887, carrier gas: nitrogen, nitrogen gas: 10 psi, compressed air: 35 psi, hydrogen gas pressure: 15 psi, detector: FID, initial temperature: 50°C, final temperature: 250°C. The peaks were identified by comparison with standard fatty acid methyl esters.

The glycemic index (GI) of individual wrap was estimated by determining how many carbohydrates (i.e., ingredients that contributed to CHO of the meal) were in each portion of the food. Then, the proportion of each carbohydrate added to the breakfast wrap was determined. The number of grams contributed by each component was divided by the total grams of carbohydrates in the food. The proportions of each wrap component were multiplied by the predetermined GI (obtained from the online GI database) of that component. The total GI of the breakfast wrap was then obtained by summation of the results (proportion of each component multiplied by its GI) of the individual components [26].

The method described by Salmerón et al. [27] was employed to determine the glycemic load (GL) for each breakfast wrap. Each food’s unique GL was determined by multiplying its GI rating by the proportion of carbohydrates it contains in a typical serving using the equation below: GL = (Net carbohydrate g × GI)/100, where, net carbohydrate = total carbohydrates in the food served.

The milled wraps were assessed microbiologically using the method of Harrigan and McCance [28]. The diluents and different agars were diluted and sterilized appropriately by autoclaving at 121℃ and 0.15 MPa for 15 min. One gram of the sample was aseptically weighed, added into 9 mL sterile saline solution, and thoroughly homogenized. The samples were serially diluted up to 10^–3 using sterile syringes. The process was repeated for the other four samples. Ultimately, 1 mL of an appropriate dilution was aseptically taken with the aid of a sterile syringe and transferred into the sterile petri dishes; the appropriate sterilized agar (cooled to 45°C) was poured into the petri dish, allowed to set, and incubated at 35°C for 24 h and 25°C for 72 h for bacteria and fungi, respectively. Enumeration of observable growths was carried out at the end of the incubation period. The colony-forming unit was obtained by multiplying the number of colonies by the dilution factor. Total mesophilic viable bacteria were examined using nutrient agar (NA), while fungi were determined using potato dextrose agar (PDA). Other microorganisms like Salmonella spp., Escherichia coli, and total coliforms were determined using deoxycholate citrate agar (DCA), eosin-methylene blue (EMB), Mac Conkey agar (MCA), respectively.

The sensory attributes of the five breakfast wraps were evaluated by twenty untrained panelists who were healthy and familiar with the consumption of edible insects and other conventional protein sources. The purpose of the assessment was communicated to the testers, and they were required to state allergies, if any. None of them were allergic to any of the sources of protein. The samples were presented to the panelists in a randomized-coded manner. Panelists had to rinse their mouths before and after tasting each sample and rate the wraps on a nine-point hedonic scale. The GF oat breakfast wraps were evaluated for taste, appearance, texture, aroma, and overall acceptability.

The data obtained after the experiment were prepared using Microsoft Excel and subjected to analysis of variance (ANOVA) to obtain the descriptive analysis. The significant differences between the GF wraps were assessed using the New Duncan Multiple Range Test (DMRT) of Statistical Package for Social Science (SPSS) software (version 22.0). Statistical significance was accepted at P < 0.05.

Table 2 shows the nutritional composition of five breakfast wraps in terms of moisture, ash, crude fat, crude fiber, protein, and carbohydrates. Moisture content was within the range of 15.01–22.18%. The protein content of GF-oat wraps followed this significant order: chicken > fish > beef > PWL > silkworm pupae. Breakfast wraps with PWL had the highest significant crude fiber content compared to the other wraps. The ash contents ranged from 2.62% to 5.54% for the wraps. GF-wrap with beef had a higher significant fat content of 18.96 % than the other wraps. The wraps with PWL and SWP had significantly higher carbohydrate content.

The vitamin composition of GF oat wrap filled with beef, chicken, fish, African PWL, and SWP is displayed in Figure 1. Comparatively, the vitamin A content of GF oat wrap with PWL competed well with that of beef, with an average value of 528.96 μg RAE/100 g. The vitamin B1 content of silkworm pupae wrap almost doubled that of the other wraps. The methylcobalamin (vitamin B12) in the insect wraps was significantly higher, followed by the wrap with fish, then chicken and beef. Contrary to the vitamins mentioned above, vitamin C was prominent in chicken and beef wraps, although they were not significantly different from GF-wraps with edible insects. In terms of vitamin E, all the GF-wraps were not significantly different except the chicken wrap. The values ranged from 4.29 mg/g to 4.97 mg/g. Sabolová et al. [32] reported that edible insect larvae can be a good dietary source of tocopherols and phytosterols. In 2010, Kinyuru et al. [33] reported α-tocopherol levels in Ruspolia differens from 161 mg/100 g to 170 mg/100 g (dry weight basis).

The content of mineral elements, expressed in mg per 100 g, is presented in Figure 2 and Table 3. In the present study, eight nutritive elements were evaluated in the individual wraps, five breakfast wraps in total, and variations in the levels of minerals resulting from the protein filling were observed. From the results, wrap with PWL could be regarded as a good source of calcium, while silkworm pupae wrap could be a good source of calcium and magnesium. Banjo et al. [34] reported a high magnesium content (7.54 to 8.21 g/100 g) found in grasshoppers and weevils. GF-wrap with beef had the predominant amount of potassium, phosphorus, and sodium, with 46.99 mg/100 g, 6.22 mg/100 g, and 4.67 mg/100 g, respectively. The zinc content for insect fillings and the conventional proteins differs significantly. Selenium and iron were abundant in wrap with mackerel fish fillings.

The AA composition of the GF oat breakfast wraps filled with different conventional and unconventional (insect) protein sources is shown in Table 4. Nutritionally, all the essential AA in all the wraps exceeded the FAO/WHO [35] recommended daily allowances except for lysine, tryptophan, and methionine. However, they can still meet above 50% of the recommended dietary allowances (RDA) for adults. Likewise, the quantity of the protein in the wraps can be adjusted to meet the daily protein needs. Leucine was discovered to be one of the most prevalent essential AA in the wraps. Overall, GF wrap filled with PWL had significantly higher essential and non-essential AA than the other wraps. Histidine from dietary sources is pivotal for children because of their body’s inability to effectively produce histidine, making it nutritionally essential for infants. The histidine contents of the GF wraps were about 18% higher than the daily requirement. The oat wraps contain appreciable amounts of glutamate and aspartate with values ranging from 9.49–12.67 mg AA/100 g protein and 6.37–8.51 mg AA/100 g protein. The total essential AA of the wraps with edible insects exceeded that of those with chicken and mackerel fish and were comparable to wraps with beef (Table 5).

The wrap with PWL displayed the highest composition of linoleic acid and overall polyunsaturated fatty acid (PUFA) (Table 6). There was a considerable variation in monounsaturated fatty acid (MUFA) levels among the samples, with the highest value of 31.78% in beef breakfast wrap, while the GF-wrap with chicken had the lowest value of 26.08%. Although beef is high in saturated fat, it also has some monounsaturated fat [36]. The SFA ranged from 50.69 % to 53.93 %, with wrap with silkworm pupae having the highest value. Arachidic acid (C20:0) was the most predominant SFA, followed by palmitic acid and then lauric acid.

The estimated GI of the GF-oat wraps is shown in Figure 3. The GI of the wraps was in this ascending order: GF-oat with PWL < GF-oat with SWP < GF-oat with fish < GF-oat with beef < GF-oat with chicken. A similar observation of low GI was reported by Zielińska et al. [37] for muffins enriched with cricket and mealworm powders. This shows that an insect diet may be preferable to fish, beef, and chicken for a low GI diet.

Moisture is one of the components that constitutes the proximal composition of foods. The high moisture contents of the breakfast wraps may not be a concern because wraps are products expected to be consumed almost immediately after production. The quantity of protein in the various wraps can be attributed to the protein quantity in the different protein sources. Nonetheless, the SWP and PWL were good protein sources and compared favorably well with beef, chicken, and mackerel fish. According to Parker et al. [40], complementary foods incorporated with PWL had elevated protein contents comparable with the study results. High fiber in PWL wrap may be attributed to the fibrous exoskeleton associated with PWL. Beef is a known source of high fat [41] which could have contributed to the high fat content of the beef wrap. According to Akande et al. [16], the presence of chitinous polymer of the insects’ cuticles may be responsible for the higher carbohydrate content of wraps with PWL and SWP. Since, the energy contents of the wraps followed the same trend as the fat content, the energy levels mainly depend on the fat content, which favors the fillings with beef because of their higher fat content.

Vitamins and minerals, often called micronutrients, are vital elements required by humans and other forms of life in diverse quantities throughout life to coordinate various physiological processes for the maintenance of health [42]. The high vitamin B1 content of the SWP wrap confirms the assertion of Rumpold and Schlüter [12] that edible insects are good sources of B vitamins. The significant quantity of cobalamin in the insect wraps revealed the products may help combat degeneration of the spinal cord, megaloblastic, and pernicious anemia, amongst other illnesses associated with the deficiency of the vitamin. Similarly, Banjo et al. [34] reported the inclusion of edible insects (termites) to improve the β-carotene, niacin, vitamin B6, and B12 content of maize. The presence of vitamin C, also known as ascorbic acid, in the wraps can make the products a suitable source of antioxidant in the human body that helps prevent cell oxidation caused by free radicals. Variations in the vitamin E contents of the wraps may be attributed to the composition of the protein sources. Vitamin E comprises four tocopherols and four tocotrienols and is important for human metabolic processes.

Many studies have demonstrated that edible insects are good sources of nutrients, including minerals [43–47]. The variations in the levels of mineral contents of the wraps can be attributed to the differences in the mineral composition of the protein fillings. The higher calcium content of the insect wraps when compared with the other wraps supports the view of Ghosh et al. [48]. According to the authors, the calcium content in all studied insects was much higher than that in conventional foods of animal origin except chicken eggs. The supply of Fe and Zn is very important in human diets because of the worldwide deficiencies in these minerals among humans [48]. A diet rich in SWP can help prevent diseases associated with iron deficiency such as anemia and stunting. Based on the findings of the study, conventional proteins are preferable when a high zinc diet is desired. The lower zinc content of the insect wraps may be attributed largely on the food consumed by the insects during growth [48]. Chicken, fish, PWL and silkworm pupae may be considered for utilization for low-sodium diets. According to the study, chicken wrap is not a good source of potassium.

Edible insects are good sources of essential AA and have been reported to increase or improve the AA of foods such as pastries, complementary foods, and baked foods, to mention a few [17, 40, 43]. Comparatively, PWL wrap was outstanding in terms of all the AA. Elemo et al. [49] reported that PWL can act as a dietary AA supplement, particularly in developing nations where they are readily available because of their AA profile. As demonstrated by Williams et al. [50], tryptophan is a limiting AA in ants, bee (Apis mellifera), and silkworm (Bombyx mori), and lysine in termites. The study support the findings of limited lysine, tryptophan, and methionine in the wraps.

Linoleic (C18:2n6) and alpha-linolenic (C18:3n3) acids are essential fatty acids in the human diet because the human body cannot produce them [51]. Meanwhile, these acids have been linked with inflammatory regulation and overall body health [52, 53] because they belong to the omega-6 and omega-3 fatty acid groups, respectively. It is also known that consuming a diet rich in linoleic acid can help prevent hypertension and cardiac conditions such as coronary heart disease and atherosclerosis [54, 55]. This shows that the wrap with edible insects offers more potential health benefits than the conventional proteins. This agrees with the study of Cheseto et al. [56], who incorporated oil extracted from Schistocerca gregaria and Ruspolia differens into cookies. It was discovered that the insects’ oils had higher concentrations of omega-3 fatty acids, flavonoids, and vitamin E compared to oils from olive and sesame. Eventually, the cookies mirrored the fatty acid profile of the parent oils. Regardless, the distinctive nutritional concentration of PWL and, to some extent, silkworm pupae, in terms of PUFA, may be linked to the environment and the diet they feed or were reared on [56, 57].

According to Brouns et al. [58], the glycemic index, or GI, is a method of ranking foods from 0 to 100 based on the influence of such foods on blood sugar levels. Higher GIs indicate foods that will cause the blood sugar to rise higher and faster than foods with lower GIs. Patients with type 1 and type 2 diabetes can benefit from consuming low-GI diets because of their ability to control blood sugar and insulin levels and insulin resistance [59].