###### Abstract  
Post-harvest activities, which include sorting, loading, unloading, and transporting, are potential factors that cause mechanical damage and bruises to fresh produce. This would directly impact fruit shelf-life and, therefore, cause economic losses. This study developed a finite element (FE) model for pear fruit where a steel impactor drop-based test was utilized. The FE model was validated by evaluating it as the experimental model in order to identify bruises of the pear fruit. Therefore, to minimize bruises on the pear fruit, a recycled polyethylene terephthalate (PET) spring-based design was proposed in order to serve as a cushioning design for pear fruits. Design of experiments and response surface methodology were performed in order to minimize the fruit bruise susceptibility response subject to different spring design parameters. The results revealed that reduced spring pitch and increased coil thickness would significantly minimize bruises of pear fruit. The recycled PET proposed design proved its efficiency in reducing FE pear fruit model bruises by about 50%. This study provides insights on assessing bruise susceptibility using finite element analysis and reusing plastic for fresh produce packaging, thus reducing loops in supply chains and achieving a circular economy. recycled polyethylene terephthalate; fruit cushion; packaging; bruising; mechanical damage; finite element analysis +
Footnote †: journal: Applied sciences  
have proven their efficiency and effectiveness in predicting bruise susceptibility, stress distribution, and deformation for a wide range of fruits and vegetables, including kiwi, fresh corn, blueberries and Goji, white radish, and pears [7; 9; 10; 11; 12; 13]. Timely identification of fruises and mechanical damage of fresh produce is a key procedure that helps enhance harvest and post-harvest procedures, therefore extending shelf-life and maintaining fruit quality [2]. Putting forward effective and useful packaging methods would minimize fruit bruising and losses in the post-harvest supply chain. Packaging is an efficient approach that serves to protect fresh crops and lower losses throughout the supply chain. Research on packaging designs for fruit cushioning is evolving. A packaging design for the Hongmeiren orange fruit has been proposed [14], and an expandable polyethylene (EPE) board was used in order to create partitions between the fruits. Each fruit was wrapped tightly with PU polyurethane foam. Authors have stated that internal packaging provides better fruit protection compared with bulk fruit packaging. Loss of citrus during transportation was reduced by about 60% when polypropylene-based crates were used for citrus packaging compared with polystyrene packages. Less environmental damage is associated with polystyrene crates, as they have the potential to be reusable and recyclable [15]. Foam-based packaging outperforms packages made from cardboard or rubber [16]. However, the performance of paper and foam board-based packaging alters depending on the fruit characteristics and tends to absorb moisture when not coated. Moreover, this type of packaging does not have the ability to be reused again and will end up being disposed of and landfilled, which will contribute to environmental damage. On the other hand, the adoption of polymer-based packages and reusable plastic containers leads to lower carbon emissions, less waste, and cost-effectiveness compared with corrugated fiberboard boxes [17; 18]. Reusable plastic packages require 39% less energy, 95% less solid waste, and 29% less total greenhouse gas emissions compared with corrugated fiberboard boxes [2]. Studies in the literature have studied early bruise detection and pear fruit response due to impact loading using the pendulum impactor test [19], hyperspectral imaging [20], structured-illumination reflectance imaging [21], and CT scanning [22]. The drop test is a commonly used test that assesses and quantifies the damage and bruise susceptibility of fruits. [PERSON] et al.