Vibration behavior of long shape vegetables

Abstract

The acoustic response method is one of the most important dynamic methods used for assessment of the mechanical texture of different fruits and vegetables. The method is based on the mechanical excitation of the sample and the assessment of its resonant frequency. Different approaches are known for the interpretation of the vibration behavior of the samples having definite shapes. According to the most widely used interpretation, the stiffness of the sample ( s ) is dependent on the resonant frequency ( f ) and the mass ( m ) of the sample. The aim was to extend the acoustic response method to typically non-spherical samples (carrot, cucumber, etc.) to find a correct interpretation of the behavior of the sample and to introduce a stiffness coefficient suitable for characterization of the mechanical properties of a long shaped sample. According to Finite Element Modeling and experimental tests on carrot samples a close correlation was found between the resonant frequency and the effective length of the sample in a given shape range. A principally new stiffness coefficient was proposed for long shaped samples. It was found to be suitable for the characterization of the hardness of the vegetables in a wide size range.

Non-destructive postharvest maturity evaluation of golden delicious apple

“…From the resulting frequency spectrum, the characteristic frequency was selected. The characteristic frequency and the sample mass were used to calculate the acoustic stiffness coefficient [5,16] …”

“…Since then, more and more research groups carried out experiments using the acoustic method. More fruits' and vegetables' stiffness, such as pear [2], peach [3], tomato [4], carrot [5], were measured successfully by this technique.…”

Quality changes of pear during shelf-life

“…From the resulting frequency spectrum the first resonance frequency was selected (Chen and De Baerdemaeker, 1993;Schotte et al, 1999). There is significant connection between the peak (characteristic) frequency of the acoustic signal and the sample's firmness, but the frequency of the vibration depends on the size, shape and texture of the product (Chen and De Baerdemaeker, 1993;Zsom-Muha and Felfödi, 2007). The characteristic frequency and the sample mass were used to calculate the firmness coefficient (Schotte et al, 1999;Valente et al, 2009 The impact method is based on the observation that the impact hammer's deceleration or the force on the rigid surface during impact of the fruit depends on the sample's firmness and elasticity (Delwiche et al, 1987;Felföldi and Fekete, 2000).…”

Chilling injury investigation by non-destructive measuring methods during banana cold storage

“…Due to its physiology and origin, among improper cold storage conditions mature green banana fruits easily suffer a chilling injury (CI) called physiological damage with its unique visible symptoms (smoky peel surface discoloration, dark-brown streaked subepidermal tissue discoloration, failure to ripen, and in severe cases, flesh browning), mainly depending on the exposure time and sensitivity to chilling temperatures under CI threshold of 13-14 °C (Kader, 2016). Objective and quantitative methods for quality assessment are required for quality control of horticultural products (Zsom-Muha and Felföldi, 2007). Chlorophyll content and chlorophyll fluorescence related novel non-destructive optical measuring methods offer the possibility to non-invasively characterise fruit responses (e.g.…”