Assessment of between-bottle homogeneity, particle size, and element content of candidate reference materials of black cricket (Gryllus assimilis) employing energy-dispersive X-ray fluorescence spectrometry.

Abstract

Crickets are widely consumed edible insects with high nutritional value, requiring reliable analytical methods for elemental characterization. Their complex matrix can cause matrix effects, making suitable reference materials essential for quality control. Because certified cricket reference materials are scarce, particularly in Brazil, this study aimed to prepare and characterize a national reference material candidate using black cricket (Gryllus assimilis). The production process was adapted to the matrix and included grinding, lyophilization, and packaging, yielding a batch of 25 bottles. The influence of particle size and between-bottle homogeneity was evaluated. Homogeneity was assessed by ANOVA, supported by Levene and Shapiro-Wilk tests, using five randomly selected bottles and three subsamples of 0.250 g per bottle. Elemental characterization was performed by energy-dispersive X-ray fluorescence. Expanded uncertainties were estimated with a coverage factor of k = 2 at approximately 95% confidence. Results showed satisfactory between-bottle homogeneity (p-value > 0.05) and indicated that particle sizes below 500 µm did not significantly affect concentrations. The candidate presented average mass fractions ± expanded uncertainty of Ca (1531.0 ± 176.5 mg kg⁻¹), Cl (5559.4 ± 1381.2 mg kg⁻¹), Cu (22.9 ± 1.7 mg kg⁻¹), Mg (1083.1 ± 295.8 mg kg⁻¹), P (10 397.0 ± 1084.6 mg kg⁻¹), and S (7608.1 ± 398.0 mg kg⁻¹). Coefficients of variation were below 11%, and expanded uncertainties remained under 30%. These results demonstrate adequate precision, reproducibility, and matrix suitability of the proposed material. The study supports continued evaluation of intra-bottle homogeneity, stability, and certification to enable its availability for laboratories performing elemental analysis of cricket-based foods, strengthening analytical reliability and food safety assessment in emerging insect protein chains worldwide. This contribution addresses national needs and supports sustainable nutrition research efforts.