*3.2. Particle Size Distribution*

Table 2 shows particle size indexes of cricket and mealworm meals at pH 4.0, 5.5 and 7.0, as well as hydrolysates generated with or without pretreatment of insect meals with HHP. As expected, and whatever the pH, higher particle sizes were obtained for both edible insect meals compared to their respective hydrolysates. At pH 4.0, cricket meal particles (D3,2 = 52.7 µm) were bigger than those at pH 5.5 (D3,2 = 47.0 µm) and pH 7.0 (D3,2 = 37.3 µm). The same tendency was observed for cricket hydrolysates. Since pH 4.0 is close to the isoelectric point (pI) of commercial cricket meal (pI close to 3.85) [60], the repulsive forces between the proteins decrease, inducing their aggregation [61]. Surprisingly, the particle size (D3,2) of mealworm meal increased with increasing pH (4.0–7.0) (values ranging from 17.0 to 41.4 µm), whereas the pI of the proteins was 3.95 [60]. This tendency was the same for mealworm hydrolysates and could be explained by the formation of disulfide bonds between mealworm proteins or even by the formation of protein–lipid complexes [62]. For both insects, the pretreatment of meals with HHP did not modify the particle sizes.




 M: insect meal, HT: control hydrolysate, HP: Hydrolysate whose insect meal has been pretreated at high hydrostatic pressures before enzymatic digestion. Values, except crude protein, represent the mean of three replicates ± standard deviation. Results with different letters are significantly different (*p* < 0.05). 2 Interaction was not significant, so lower-case letters ( a , b , c , d , e ) represent insect effect on results and upper-case letters (A, B , C) represent treatment effect on results.


**Table 2.** Particle size distribution indexes of cricket and mealworm meals and hydrolysates generated with or without HHP pretreatment of meals.

M: insect meal, HT: control hydrolysate, HP: Hydrolysate generated by the treatment of insect meal with high hydrostatic pressures prior to enzymatic hydrolysis, D(3,2): area-based mean particle diameter. Values represent the mean of three replicates ± standard deviation. <sup>1</sup> Results with different letters within an insect are significantly different (*p* < 0.05). <sup>2</sup> Lower-case letters (<sup>a</sup> , b ) represent insect–treatment interaction and upper-case letters (A, B ) represent insect–pH interaction.
