**2. Development**

#### **2.1 Sensory barriers to the massification of insect consumption**

There are several insect-based foods on the market such as cereal bars, drinks, pastas, candies, snacks, hamburgers, for human consumption [51, 52] and made with different concentrations of insect flour and oil [53–55]. The main problem lies with the acceptance of this type of food by people who are not familiar with entomophagy

*Perspective Chapter: Technological Strategies to Increase Insect Consumption – Transformation… DOI: http://dx.doi.org/10.5772/intechopen.108587*

(insect consumption), such as people from Western cultures, who often feel disgust, perceive insects as unpleasant, and reject their consumption [56]. In several surveytype studies, it was found that insect consumption could be better accepted if "insects did not look like insects" [57–59].

People who would be willing to consume insects describe some unpleasant sensory characteristics, such as: i) unpleasant odors [60, 61], identified as smelling of fungi, algae, fishy, and earthy [62–64], ii) unpleasant tastes of fish, fungi, bitterness [65, 66], iii) dark brown color of flour causing rejection [67], iv) grainy and rough texture of flour and whole insects [62, 63], and soft and oily texture in larvae [68] (**Figure 1A and B**), and v) unpalatable appearance of whole insects (**Figure 1C**) and meals, such as BSFL meal (**Figure 1E**) [69]. Additionally, processing to convert whole larvae/insects into meal (**Figure 1D**) can worsen these sensory perceptions, as Maillard reactions occur during the thermal process [70]. These reactions alter the color, odor, and flavor of insect flours in a negative way [71] and reduce the availability of some nutrients such as vitamin B12, potassium, phosphorus, sodium, some amino acids such as lysine [66]. There is also generation of unpleasant volatiles such as aldehydes, ketones, alcohols, esters, hydrocarbons, sulfur compounds and phenols, which generate unpleasant aromas [65, 72]. Thermal processing also generates darkening; for example, fly and mealworm larvae are cream-colored with yellow and orange shades (**Figure 1A**) and the meal obtained from these is dark brown (**Figure 1E**), due to the generation of brown and black coloring pigments such as melanoidins [66, 73]. The chitinous exoskeleton of insects is resistant to crushing [74]; therefore, the flour obtained after the milling process has granular texture, due to the large particle size (1.0–1.4 mm) of insect flours [53, 75], compared with flours of plant origin for example, wheat flour, which has a small particle size of about 100–150 μm [76].

The color of insect oil varies in yellow shades, and their melting point is variable depending on the profile and fatty acid content. For example, oil from BSFL contains lauric acid as the main fatty acid (21–29% of the total fatty acids, depending on the larval diet) [77]. Lauric acid is a saturated fatty acid, which gives the oil a high melting temperature (≈ 43°C). The oil is solid at room temperature, limiting its use as a food ingredient and making the incorporation into feed and/or diet formulations complex [78]. During oil processing, negative sensory changes also occur, mainly in oils with higher polyunsaturated fatty acid content, which tend to oxidation, producing odors and flavors described as "rancid and unpleasant" [60, 61]. Crude oil contains various components such as gums, free fatty acids, aromatic residues, and pigments, which negatively affect flavor, nutritional value, appearance, and stability [79].

#### **Figure 1.**

*Appearance of whole insects, A: BSFL, B: mealworm larvae, C: adult house crickets, D: processing of insects into food ingredients, such as flour (E) and oil (F).*

The addition of whole or processed insects to a food negatively affects its sensory quality, even if added in small amounts (<5% for flour), because they contribute to characteristic flavors and aromas, considered unpalatable to people, affect the appearance and texture, and darken the product [54, 80–82]. Therefore, the addition of insect-based ingredients to foods remains a major challenge.

### **2.2 Common food ingredients from insects: meal and oil**

The main insect-based ingredients produced in the world have been whole meal and defatted meal and oil, which are obtained by relatively simple processing and are widely used in the food industry [50]. The following processes are used to obtain flour: blanching, drying, grinding, and addition of additives [83, 84]. Blanching is the process where whole insects (larvae and/or adults) are placed in boiling water, and then removed and immersed in ice water to stop the thermal process. Blanching is used as a pretreatment to reduce the microbial load of bacteria and fungi and inactivate the degradative enzymes responsible for spoilage, but does not affect bacterial spores [85–88]. Blanching time can be from seconds to 16 minutes, with a 5-minute average, and this process can be repeated several times for differing periods of time. The ratio of insects/water used has been 1/10–1/12. The time of immersion in ice water is from 30 seconds to 5 minutes. Between the blanching and cooling processes in water, the insects can be drained and crushed. Sterilizing solutions of 5% NaCl can also be used in this process [50]. The second process the insects receive is drying to reduce total water content and water activity, decreasing degradation reactions, including enzymatic reactions and those produced by microorganisms [89, 90]. The drying methods used include air convention dryer, solar drying, oven drying, smoke drying, frying pan, freeze drying, microwave-assisted drying, fluidized bed drying, oven drying with air circulation, and ultrasound-assisted aqueous extraction. Of all these methods, the most widely used for the industrial production of insect meal is oven drying in conventional hot air drying, using temperature ranges between 40 and 80°C for 8 to 48 hours until the sample reaches constant weight [50]. The last process is milling, which mechanically reduces the whole insect to the consistency of powder or flour [91]. For grinding, the use of a roller mill [75], blade mill [92, 93], colloid mill [94], or mechanical disruptor [60] has been described with times varying between 2 and 10 minutes, depending on the method chosen [60, 93].

To obtain defatted meal, it is necessary to extract the oil. Oil extraction is commonly performed with organic solvents, such as hexane, ethanol, isopropanol, methanol, petroleum ether, acetone, diethyl ether, and their mixtures [94–102]. Solvent extraction techniques involve partitioning between two immiscible liquids, continuous extractions, or batch extraction of solids. This process consists of three stages: pretreatment, desolventization, and solvent refining [103]. Although extraction with organic solvents has been the most widely used for oil extraction, other methods recognized as "green" for being more innocuous have also been studied, such as extraction with supercritical CO2 [104–106]. The latter is a promising process, with a good percentage of defatting; however, it is more expensive. High hydrostatic pressure extraction has also been investigated [107, 108]. Insect oil has been used in the formulation of human food [109, 110], salmonid diets [111, 112], complete feeds, and pet snacks [48].

The two most important nutritional components in insect meal are protein and fat. The ranges of crude protein and crude fat content of whole and defatted meal of the insects most commonly used in human food development and most consumed by animals are presented in **Table 1** [14, 94, 99, 113–120]. Of the three insects
