1-Methylcyclopropene (1-MCP), storage time, and shelf life and temperature affect phenolic compounds and antioxidant activity of ‘Jonagold’ apple

Authors: MA, YURONG - Shandong Agricultural University; BAN, QINGFENG - Shandong Agricultural University; SHI, JINGYIN - Shandong Agricultural University; DONG, TIANTIAN - Shandong Agricultural University; Jiang, Cai-Zhong; WANG, QINGGUO - Shandong Agricultural University

Submitted to: Postharvest Biology and Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/26/2018
Publication Date: 12/31/2018
Citation: Ma, Y., Ban, Q., Shi, J., Dong, T., Jiang, C., Wang, Q. 2018. 1-Methylcyclopropene (1-MCP), storage time, and shelf life and temperature affect phenolic compounds and antioxidant activity of ‘Jonagold’ apple. Postharvest Biology and Technology. 150:71-79. https://doi.org/10.1016/j.postharvbio.2018.12.015.
DOI: https://doi.org/10.1016/j.postharvbio.2018.12.015

Interpretive Summary: Apple, one of the most consumed fruit, is rich in bioactive compounds such as phenolics. Apple phenolics have many physiological functions, such as antioxidation, antisepsis, anti-inflammation, antitumor and prevention of coronary disease. Major phenolics in apples include chlorogenic acid, phloridzin, procyanidin B1 and B2, catechin, epicatechin, quercetin glycosides, and cyaniding-3-galatoside. Profile of phenolics in apples is largely dependent on the variety of apples. Their distribution in peel and flesh also varies. The contents of phenolics in apples also changed during the development in fields and after harvest. Nonetheless, there was discrepancy in the literature regarding postharvest changes in apple phenolics. For instance, no significant changes occurred in simple phenolics, flavonoids and anthocyanin content of later picked ‘Delicious’ and ‘Ralls’ apples after cold storage for 4 or 5 months, whereas significant decrease in content of simple phenolics was found in early picked apples after 3 months storage. As an inhibitor of ethylene, 1-methylcyclopropene (1-MCP) is widely used in the storage of apples. Its influence on the changes of phenolics varies according to the apple variety tested. The beneficial combined effects of pre-storage 1-MCP treatment and Controlled atmosphere (CA) storage on phenolic composition in ‘Cripps Pink’ apples during 160 d storage were also found. Moreover, it was found that phenolic compounds responded differently to 1-MCP treatment. 1-MCP maintained the concentration of anthocyanin, but showed no influence on flavonols and flavan-3-ols. Despite the changes in phenolics after harvest of apples and the effects of 1-MCP were extensively studied, the results were not consistent. Also, few research was focused on the changes of phenolics, flavonoids and antioxidant activity during shelf life. Furthermore, different individual phenolics in response to cold storage, shelf life and 1-MCP treatment were rarely referred to. Therefore, in this study, the diverse influence of storage time, shelf life, shelf temperature and 1-MCP treatment on phenolics, flavonoids and antioxidant activity as well as their differences between apple peel and flesh of ‘Jonagold’ apple were investigated. We found that hyperoside and chlorogenic acid were the most abundant phenolic compounds in the peel and flesh, respectively. The flesh had lower concentrations of individual phenolics, total phenolics, flavonoids and lower antioxidant activity than the peel. In addition, the profiles of phenolics as well as the changing patterns of individual phenolics also differed between the peel and the flesh. After long-time storage (180 d), the most deterioration was observed in the level of hyperoside (26.7 %) in the peel and total phenolics (35.0 %) in the flesh. During the 90 to 180 d storage period, there was a dramatic decrease in hyperoside and rutin in the peel, chlorogenic acid in the flesh, flavonoids and antioxidant activity both in the peel and the flesh. Individual phenolics exhibited different stabilities at early stage after harvest. Shelf temperature, shelf life and 1-MCP had little influence on the stability of hyperoside in the peel of fresh harvested apples, whereas dramatic influence on chlorogenic acid was observed in the flesh. Application of 1-MCP significantly alleviated the reduction in the contents of hyperoside in the peel, chlorogenic acid in the flesh, total phenolics, flavonoids and antioxidant activity in both the peel and flesh during storage and shelf life. These results provide meaningful information for understanding the response of phenolic compounds to cold storage, shelf life and 1-MCP treatment.

Technical Abstract: The effects of 1-methylcyclopropene (1-MCP) treatment, storage time, and shelf life and temperature on phenolic concentrations and antioxidant activity in apple peel and flesh of ‘Jonagold’ apple (Malus domestica Borkh) have been investigated. Hyperoside and chlorogenic acid were the most abundant phenolic compounds in the peel and flesh, respectively. The flesh had lower concentrations of individual phenolics, total phenolics, flavonoids and lower antioxidant activity (determined by 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging assay) than the peel. In addition, the profiles of phenolics as well as the changing patterns of individual phenolics also differed between the peel and the flesh. After long-time storage (180 d), the greatest decrease of concentrations was the concentrations of hyperoside (27 %) in the peel and total phenolics (35 %) in the flesh. Also, during the 90–180 d storage period, hyperoside and rutin in the peel, chlorogenic acid in the flesh, and flavonoids and antioxidant activity decreased in both peel and flesh tissues. Individual phenolics exhibited different stabilities during the early stages after harvest. 1-MCP reduced the reduction in the concentrations of hyperoside in the peel, chlorogenic acid in the flesh, and total phenolics, flavonoids and antioxidant activity in both the peel and flesh tissues during storage and shelf life. However, for quercetin and rutin, the protective effect of 1-MCP was only observed during the shelf life period. Overall, phenolic compounds responded variously to storage, shelf life, shelf temperature and 1-MCP treatment.