title: Application of vibration response technique for the firmness evaluation of pear fruit during storage.
abstract: Storage conditions of pear affect its subsequent softening process and shelf life. Measurements of firmness have traditionally been carried out according to the Magness Taylor (MT) procedure; using a texture analyzer or penetrometer in reference texture tests. In this study, a non-destructive method using Laser Doppler vibrometer (LDV) technology was used to estimate texture firmness of pears. This technique was employed to detect responses to imposed vibration of intact fruit using a shaker. Vibration transmitted through the fruit to the upper surface was measured by LDV. A fast Fourier transform algorithm was used to process response signals and the desired results were extracted. Multiple Linear Regression models using fruit density and four parameters obtained from modal tests showed better correlation (R(2) = 0.803) with maximum force in Magness Taylor test compared to the models that used only modal parameters (R(2) = 0.798). The best polynomial regression models for pear firmness were based on elasticity index (EI) and damping ratio (η) with R(2) = 0.71 and R(2) = 0.64, respectively. This study shows the capability of the LDV technique and the vibration response data for predicting ripeness and modeling pear firmness and the significant advantage for commercially classifying of pears based on consumer demands.
authors.affiliation: Agricultural Machinery Engineering Department, Science and Research Branch, Islamic Azad University, Tehran, Iran.
authors.forename: Z
authors.initials: Z
authors.lastname: Oveisi
authors.affiliation: Agricultural Machinery Engineering Department, Science and Research Branch, Islamic Azad University, Tehran, Iran.
authors.forename: S
authors.initials: S
authors.lastname: Minaei
authors.affiliation: Agricultural Machinery Engineering Department, Faculty of Agricultural Engineering and Technology, University of Tehran, Karaj, Iran.
authors.forename: S
authors.initials: S
authors.lastname: Rafiee
authors.affiliation: Agricultural Engineering Research Institute, Karaj, Iran.
authors.forename: A
authors.initials: A
authors.lastname: Eyvani
authors.affiliation: Agricultural Machinery Engineering Department, Science and Research Branch, Islamic Azad University, Tehran, Iran.
authors.forename: A
authors.initials: A
authors.lastname: Borghei
keywords: Firmness; Laser doppler vibrometer; Multivariate linear regression; Non-destructive measurement; Storage