Chilling-related browning of ‘Wonhwang’ pear cortex is associated with the alteration of minerals and metabolism

Authors: LWIN, HNIN PHYU - Chung-Ang University; TORRES, CAROLINA - Washington State University Extension Service; Rudell, David; LEE, JINWOOK - Chung-Ang University

Submitted to: Scientia Horticulturae
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/5/2023
Publication Date: 7/7/2023
Citation: Lwin, H., Torres, C.A., Rudell, D.R., Lee, J. 2023. Chilling-related browning of ‘Wonhwang’ pear cortex is associated with the alteration of minerals and metabolism. Scientia Horticulturae. 321. Article 112321. https://doi.org/10.1016/j.scienta.2023.112321.
DOI: https://doi.org/10.1016/j.scienta.2023.112321

Interpretive Summary: ‘Wonhwang’ is a variety of Asian pear with a growing market share in Republic of Korea and Asia, in general. This pear can only be stored for up to 3 months under refrigeration with any expectation of acceptable market quality following the important distribution and retail period of the cold chain where any economic losses are compounded. Unfortunately, this pear cultivar is prone to develop internal browning during cold storage, rendering the fruit unmarketable. We anticipated that natural chemical levels would be different between symptomatic (browned) tissue, surrounded asymptomatic tissue, and healthy flesh tissue from fruit not afflicted with internal browning. Our results indicate that, indeed, levels of natural chemicals associated with cellular energy production, fruit flavor, and nutritive value were all different. These results will be the basis for further work directed towards using fruit chemistry to indicate whether pears are destined to develop costly internal browning for early mitigation or removal from the cold chain.

Technical Abstract: ‘Wonhwang’ pear (Pyrus pyrifolia Nakai) is affected by a wide range of physiological disorders, especially internal browning (cortex browning) during long-term cold storage and subsequent shelf life. Postharvest fruit quality and metabolic changes of many Asian (P. pyrifolia) pears are well characterized, but little is known about the minerals and metabolites associated with internal browning induction and development in ‘Wonhwang’ pear during cold storage. The present study compares minerals and metabolites in cortex tissues of healthy fruit as well as symptomatic (browned) and sound tissues from fruit with internal browning that developed during long-term cold storage. P, K, Ca, sorbitol, shikimic acid, palmitic acid (C16:0), linoleic acid (C18:2), a-linolenic acid (C18:3), methionine, 1-hexenol, and (Z)-3-hexenal were lower in browned tissue than in healthy and sound tissues. In contrast, levels of glucose, fructose, fumaric acid, valine, leucine, isoleucine, lysine, phenolic compounds, lignoceric acid (C24:0), ethyl esters, and some volatile aldehydes were highest in browned tissue, compared with the other tissues. Many ethyl esters, aromatic amino acids, branched-chain amino acids, phenolic compounds, soluble solids content, fructose, and glucose were associated with internal browning. Furthermore, tryptophan metabolism, arginine biosynthesis, alanine, aspartate, and glutamate metabolism, a-linolenic acid metabolism, and glycine, serine, and threonine metabolism were the pathways most impacted by internal browning. Overall, the largest metabolic differences appeared between damaged and asymptomatic cortex as several metabolic pathways were influenced by internal browning.