Reducing postharvest food losses in organic spinach with the implementation of high tunnel production systems

Fresh produce constitutes 44% by weight of the global food losses and waste. Postharvest losses of fresh produce are closely related to the preharvest field conditions during growth. In the Central US, many small acreage vegetable growers are utilizing high tunnels, which have been successful in increasing the yield of several crops. Little is known about the effect of this production system on the postharvest losses. This study tested the hypothesis that the production system will affect the postharvest losses of organic spinach (Spinacia oleracea, “Corvair”) when stored at 3 or 13 °C. Comparative open field and high tunnel trials were conducted from 2015 to 2017. Postharvest losses were evaluated with regard to the spinach quality characteristics and shelf life. During storage at 3 °C, there were no major quality differences between the spinach grown in the two production systems. During storage at 13 °C, in both years, spinach grown in the high tunnels had 1.2 to 2.3% higher water content than spinach grown in the open field. In the second year, high tunnel spinach stored at 13 °C had a lower respiration rate (P < 0.05) and a slower rate of yellowing as indicated by higher chlorophyll content (P < 0.001), significantly lower lightness values, and significantly higher hue values than open field spinach. The high tunnel spinach demonstrated longer shelf life in year 1 and higher quality towards the end of storage in year two when compared to open field spinach when stored at 13 °C. This is the first study to examine the effect of the high tunnel production system on the postharvest quality and losses of spinach. Our results indicate that high tunnels can reduce the postharvest food losses of spinach when stored at 13 °C, due to increased water content and decreased senescence rate.