Explorative study of using infrared imaging for temperature measurement of pallet of fresh produce

Abstract

Food industry is currently using thermal imaging to measure temperature of fresh produce, but there is no comparative study between temperatures measured traditionally by temperature probes and the temperatures measured by thermal imaging reported in the literature. This paper is exploring the possibility to use surface temperature measured by infrared (IR) thermal imaging versus temperatures measured by a network of temperature sensors. Two different types of vegetables (chard and cucumber) were covered with three different types of covers (Tyvek® material, Metalized PET and Metalized PET with bubble wrap layer) which are designed to protect shipments of produce against temperature abuses. Each cover/produce combination was exposed to a temperature warm up regime in order to simulate a break in the cold chain during distribution, and it was monitored with the thermal IR camera and temperature sensors for comparisons. Results of temperature measured by thermal imaging showed a differential between 1.9 and 6 °C compared to temperature measured by thermal sensors. These found differences are unacceptable for fresh produce temperature control. The high emissivity of metalized PET produced significant reading errors when using the IR camera. Tyvek® cover had more consistent results due to a higher emissivity value that is closer to the value used by the IR camera. This study is of great value since it is giving instructions of how the thermal camera should be used for temperature measurements for covered pallets.