Acoustic signals associated with the multifractal breakage patterns of brittle and crispy foods

Abstract

Food breakage is an important issue in industry and is coupled to acoustic signals. The aim of this work was to analyse the breakage phenomenon with time in commercial crispy and brittle foods, using acoustic techniques and mechanical-textural features using Digital Image Analysis (DIA) and fractal analysis. Breakage patterns were coupled to the acoustic signals of six brittle foods by capturing the audio during breaking and then, applying DIA to audio signals and breakage patterns, which depicted multifractal spectra. Results showed that samples with less irregular acoustic patterns presented higher spectrum amplitudes and low generalised fractal dimension (GFD) (1.245 ± 0.045) and lacunarity (Ʌ) (0.269 ± 0.209) while materials presenting the largest irregularity had shorter spectrum amplitudes and depicted high GFD (1.656 ± 0.177) and Ʌ(0.745 ± 0.007). For global analysis of the transverse and longitudinal rupture pattern, four breakage zones were defined. In all cases, multifractal breakage patterns were associated to multifractal acoustic signals.