The use of underutilized biomass improves resource-use efficiency and reduces agricultural waste, particularly in temperate systems cultivating tropical crops. Papaya (Carica papaya L.), grown as an annual crop in these systems, produces substantial trunk biomass that is typically discarded after harvest. This study evaluated the potential of papaya trunk xylem rays as an edible resource through compositional, sensory, and functional analyses. Trunks were harvested at the end of the fruiting period (December) and after exposure to a cold wave (January) and were classified by organ types and maturity level. Xylem rays showed moisture and carbohydrate contents comparable to those of green papaya fruit, and were judged as edible by all panelists (100%) in December-harvested samples. However, exposure to a cold wave reduced sweetness and increased bitterness, resulting in decreased overall acceptability. Nevertheless, boiling effectively reduced bitterness and improved palatability even in cold-exposed samples. In addition, xylem rays exhibited higher total polyphenol content than green papaya fruit, while showing comparable DPPH radical scavenging activity. These results suggest that xylem rays have potential as an edible plant resource with antioxidant-related properties, contributing to resource-use efficiency and potentially providing opportunities for biomass valorization in temperate production systems.
Oka et al. (Sun,) studied this question.