Artificial fruit for monitoring the thermal history of horticultural produce in the cold chain

Abstract

There is a need for more realistic monitoring of fruit pulp temperature history throughout the cold chain at a higher spatial resolution inside the cargo. Particularly solutions that are easy to install in a commercial setting are required. For this purpose, a novel kind of fruit simulator -an artificial fruit -has been designed, manufactured and tested. Using a biomimetic approach, it was engineered specifically to match the thermal response of real fruit as close as possible. The artificial fruit is composed out of a thin plastic shell, which mimics the exterior size, shape, surface texture and color of the fruit of interest. This shell is filled with a mixture that has similar thermal properties as real fruit as it is basically composed out of the same components. Two self-powered data loggers with a built-in sensor are integrated in the artificial fruit. These different components of the artificial fruit were combined successfully into a manufactured prototype. The thermal response of an artificial apple fruit during cooling was evaluated against that of 10 real apples. The cooling time of the artificial fruit was within 5% of that of the real fruits. The artificial fruit also had a more accurate thermal response than that of water-filled fruit simulators, with which differences up to 16% were found. The uniformity in size, shape and sensor location of the artificial fruit also enables it to measure fruit pulp temperature in a much more repeatable manner than with real fruit. A particular advantage of the artificial fruit is that it can be packed directly with the fresh produce in a commercial setting, by which multiple locations inside the cargo can easily be monitored. This novel sensor system thus provides an improved method to identify heterogeneities in cargo cooling, and associated quality issues. The artificial fruit is especially of interest for monitoring fruit pulp in precooling facilities, cold stores, ripening facilities and refrigerated containers.

Development of an artificial fruit prototype for monitoring mango skin and flesh temperatures during storage and transportation

“…To simulate the flesh, agar concentrations of 5, 10 and 15% were used with each artificial skin. Previous studies have shown that these agar concentrations have similar thermal behavior to those of fruit flesh (De Castro et al, 2004Soto-Reyes et al, 2015;Defraeye et al, 2017). However, studies attempting to simulate mango flesh have never been accomplished before.…”

“…Recent studies have accurately conducted fruit thermal simulations. A thermal simulator made for apples had skin composed of a fine plastic layer which simulates the geometry of size, shape and surface texture (Defraeye et al, 2017). Its flesh consisted of water-carbohydrate-air (WCA) compound mixed with gel (Defraeye et al, 2017).…”

“…A thermal simulator made for apples had skin composed of a fine plastic layer which simulates the geometry of size, shape and surface texture (Defraeye et al, 2017). Its flesh consisted of water-carbohydrate-air (WCA) compound mixed with gel (Defraeye et al, 2017). Prototype skin and flesh temperatures were measured and the coefficient of determination (R²) to evaluate the artificial apple fruit reached 95% significance (Defraeye et al, 2017).…”

“…However, fruit flesh temperature shows a thermal lag due to its inertia and fruit physiology does not react as fast as changes in air temperature. In addition, for climacteric fruit, maturity stage can also affect cooling time due to the effect of physico-chemical quality parameters on flesh thermal behavior (Defraeye et al, 2017;Vasconcelos et al, 2019). Our previous study has shown that mango cooling time is strongly affected by physico-chemical quality (Vasconcelos et al, 2019).…”

“…Previous studies have attempted to develop artificial oranges and apples prototypes to monitor fruit tissue temperatures (De Castro et al, 2004Vigneault et al, 2006;Tanaka et al, 2012;Soto-Reyes et al, 2015;Defraeye et al, 2017). However, these studies did not consider the effect of fruit physico-chemical quality on fruit thermal behavior.…”