Effect of vibration stress on quality of packaged grapes during transportation

This study was conducted to determine vibration characteristics of packaged grapes during truck transportation and mechanical injury by such vibration stress. Vibration impact generated during a major freight distribution route of packaged grapes in Korea was measured in terms of the power spectral density (PSD). By using the PSD profile measured at the rear side of truck, a simulated transportation experiment was carried out to investigate how vibration stress influenced quality deterioration in grapes. The quality degradation of grapes under vibration stress and grapes without vibration stress was determined by measuring quality index indicators such as weight loss, soluble solids content (SSC), and ethylene production. Both grape groups were stored at refrigeration condition (1-2 °C, 65-75% RH) for 30 consecutive days. As compared to the control grape group, the decrement of weight loss and SSC in grape group suffered from vibration was 6% and 1.3° Brix, respectively; while ethylene production was increased by 7 nL/g․hr. The results clearly showed that vibration stress could result in the degradation and rapid ripening of packaged grapes.