Influence of 1-Methylcyclopropene on the Antioxidants of ‘Red Cap’ Apples during Transportation and Shelf Life

Abstract

The dietary properties of apples make them, along with the other fruits and vegetables, the basis of many slimming or pro-health diets. Availability of apples throughout the year is ensured by various storage technologies, including the use of ripening inhibitors. This experiment focused on the assessment of the effect of various variants of inhibition of apple ripening processes, i.e., 1-methylcyclopropene (1-MCP), ultra-low-oxygen storage (ULO) or modified atmosphere (MAP), in order to provide the consumer with apples with comparable high nutritional values. An important aim of the experiment was to determine the effect of the above-mentioned factors on changes in the content of polyphenols and antioxidant capacity in conditions of apple distribution at high temperatures, i.e., above 25 °C. The experiment consisted of several stages of fruit distribution: (I)—treatment of 1-MCP apples immediately after harvest, (II)—storage in ULO, (III)—simulated long-distance transport under normal atmosphere cold storage (NA) and Modified Atmosphere Packaging (MAP), (IV)—simulated rotation (15 days) under high-temperature conditions of 25 °C. Evaluation gave the basic characteristics of the fruits that characterize their health-promoting properties, i.e., total polyphenols (TPC), phenolic acids and flavonols, and antioxidant activity (AA). All indicators were assessed separately for apple peel and flesh. The experiment showed that the content of antioxidants in apple peel is from 230 to 370% higher than in the flesh, depending on the group of ingredients assessed. The peel of fruit treated with 1-MCP was distinguished by a higher content of phenolic acids and flavonols than the untreated fruit, especially after 20 weeks of stored in ULO. The effect of 1-MCP on AA in the peel of the fruit was moderate; however, apples untreated with 1-MCP were more likely to lose AA, especially when transported under normal cold storage conditions. The content of assessed compounds in the apple flesh was more stable than in the peel. The content of TPC and phenolic acids in apple flesh either decreased or remained almost unchanged after 15 days of shelf life. An increase in AA was observed in fruit flesh not stored in ULO, especially in apples treated with 1-MCP. After 10 and 20 weeks of storage in ULO, AA was not determined by experimental factors. The use of 1-MCP and the transport of apples in MAP can reduce the loss of phenolics after long-distance transport and distribution.