Crispness and Crunchiness Judgment of Apples Based on Contact Acoustic Emission

Abstract

Contact acoustic emission (AE) measurement, together with a puncture test, were used to evaluate the crispness and crunchiness of three apple cultivars. A storage program was used to induce changes in apple crispness and crunchiness. The instrumental measurements were compared with the results of sensory evaluation. It was found that crispness and crunchiness could be evaluated instrumentally by measuring firmness, AE events, mean AE amplitude or the product of AE events and mean AE amplitude. For one cultivar, however, firmness was not correlated with any sensory attribute. Generally, the best correlation with sensory attributes was found for the exponential value of AE events. Contact AE allows the measurement of sensory crispness or crunchiness for a given apple cultivar or independently for any apple cultivar. Contact AE can be considered as a useful method for the evaluation of sound properties of wet‐crisp foods. PRACTICAL APPLICATIONS Contact acoustic emission method can be used for instrumental evaluation of crispness and crunchiness of apples. The method allows more accurate evaluation of these attributes than firmness measurement. There is a chance to extend the application to other wet‐crisp foods and to use the method together with other destructive tests, like texture profile analysis or single edge notched bend.

The effect of Ca2+ and cellular structure on apple firmness and acoustic emission

“…For the instrumental prediction of the sensory attributes of apples, like crispness, crunchiness, hardness or overall texture, the use of a summary number of AE events [7] or AE counts [6] in puncture tests gave satisfactory results. The prediction could be improved when both the sum of AE counts and fruit firmness were included in a principal component regression (PCR) model [25].…”

“…Recently, the AE method, which uses a sensor in contact with the sample, has been shown as a useful method for testing plant tissue cracking [5,9] and for instrumental evaluation of apple texture [6,7,25]. For the instrumental prediction of the sensory attributes of apples, like crispness, crunchiness, hardness or overall texture, the use of a summary number of AE events [7] or AE counts [6] in puncture tests gave satisfactory results.…”

“…The previous studies proposed hypothesize that AE signal is generated mainly by ruptured cell walls due to elastic properties and the capability of generating elastic waves when ruptured [5,7]. The amplitude of AE signal is proportional to stress at the moment of energy release [28]; therefore, one can expect that the tensile strength of cell walls affects acoustic measurement due to the greater amount of energy released in the process.…”

“…Acoustic emission (AE) is the phenomena of sound generation during rapid mechanical breakdown of a material and, as a method of material characterization, is also currently investigated for instrumental texture evaluation of parenchymatous tissue [3][4][5][6][7].…”

Extruded Bread Classification on the Basis of Acoustic Emission Signal With Application of Artificial Neural Networks

“…Tests carried out both in the case of dry (Duizer, 2001;Marzec et al, 2007aMarzec et al, , 2007b and wet (Zdunek et al, 2010a(Zdunek et al, , 2010b farm and food products indicate that, depending on storage conditions, changes in mechanical parameters of food products could be noticed by changes in AE signal. What is more, differences in the signal for the same product type but different varieties, such as rye bread and wheat bread are perceived (Marzec et al, 2007b).…”