Sensory, Instrumental and Acoustic Characteristics of Extruded Snack Food Products

Abstract

Corn based extrudates produced at three moisture contents and stored at four water activities were evaluated by sensory evaluation and instrumental tests in order to assess how processing and storage affect the sensory characteristics of the products. Acoustic signatures were collected by recording the sounds produced as the samples were bitten through with the back molars. These signatures were analyzed by fast Fourier transformation and the Kolmogorov dimension of fractal analysis. Products with a low moisture content and water activity were crisper than those at a higher moisture content and water activity. Fourier transformations of the data showed peaks between 1 and 2 kHz and between 6 and 7 kHz. Fractal analysis of the normalized raw time‐amplitude curves showed significant positive correlations between fractal dimensions and the sensory characteristics of crispness, crumbliness and pitch.

Standard Scales for Crispness, Crackliness and Crunchiness in Dry and Wet Foods: Relationship With Acoustical Determinations

“…Biting with the back molars Duizer et al 1998 Fractures in an abrupt manner after applying a relatively small force on the product.…”

Crispy banana obtained by the combination of a high temperature and short time drying stage and a drying process

“…If the increase in hardness occurs as water activity increases, this can be explained by the fact that water acts as a plasticizer, thereby increasing the hardness of the material. This is due to the fact that the plasticized structure does not disintegrate easily, allowing the sample to remain intact and offering more resistance to deformation (Duizer and Campanella, 1998;De Belie et al, 2000). Katz and Labuza (1981) discussed the importance of water activity (a w ) in crispness of snack food products.…”

Evaluation of the Internal Quality of Agricultural Products using Acoustic Vibration Techniques

“…Stec et al (1989) examined 'Hayward' kiwifruit of differing degrees of ripeness and found that the preferred firmness at eating ripeness varied among panelists. Duizer et al (1998) found that sensory characteristics (crispness, pitch, and crumbliness) correlated significantly to the fractal dimension. Harker et al (2002) investigated the relationship between various instrumental and sensory measurements of the texture of apples ('Cox's Orange Pippin', 'Pacific Rose', 'Granny Smith', 'Royal Gala', 'Fuji', and 'Red Delicious').…”

“…The FFT has been a powerful tool in frequency analysis (Dacremont, 1995;Lee et al, 1988). A more recent approach for evaluating amplitude-time curves is the determination of their jaggedness or fractal dimensions (De Belie et al, 2002;Duizer et al, 1998). Peleg ( , 1997 reviewed the use of fractal analysis in food science and discussed its use as a measure of the irregular stress-strain relationship for cellular solid foods.…”

“…Usually, such meaning is given by verbal definitions. For instance, Duizer et al (1998) defined "crispness" as the combination of the noise produced and the breakdown of the product as it is bitten entirely through with the back molars. Definitions of sensory texture attributes are critical in sensory evaluation.…”