Influence of ripening on the ethylene and carbon dioxide production during storage of plum fruits

KOŽISKOVA, J., GOLIAS, J.: Infl uence of ripening on the ethylene and carbon dioxide production during storage of plum fruits. Acta univ. agric. et silvic. Mendel. Brun. , 2012, LX, No. 8, pp. 133–140 The fruits of 13 plum cultivars were analysed at two diff erent stages of maturity: fi rst when they were ready for picking according to conventional commercial criteria, and again a er seven days of maturation at 20 °C in a normal oxygen atmosphere during shelf life. Firmness, soluble solids concentration (SSC), respiration rate and the production of ethylene were measured. In the period of over-ripening SSC increased, and no diff erences were found in relation to the cultivar. The fruits in this period were physiologically in a phase of reduced intensity of respiration, while production of ethylene increased and was associated with the earliness of the cultivar. Cultivars with a short vegetation period produce more ethylene while late-maturing cultivars have a low potential for ethylene production. Based on post-harvest changes in the tested quality factors, the late-ripening plum cultivars (cv.) ‘Jojo’, ‘Topend’, ‘President’, ‘Tophit’ and ‘Elena’ have higher storage potential. Changes in ethylene production in response to shelf life seem to play a regulatory role in fruit fi rmness. A high signifi cant negative correlation was detected between levels of skin fi rmness and ethylene production. plum fruits, cultivar, ripening, ethylene, respiration, fi rmness Plums (Prunus domestica L.) are members of the Rosaceae family, genus Prunus along with other stone fruits such as peaches, apricots, nectarines, cherries. Based on a survey done by Blažek (2007) the author commented that plums constitute the most numerous and diverse group of fruit tree species traded internationally. Plums rank as the fourth most important fruit species of temperate area. The plum has been categorised as a climacteric fruit, with a high rate of respiration between the end of the fruit’s development and the start of the ripening process. The increase in respiration is concomitant with an enhancement of ethylene synthesis (KAYS and PAULL, 2004), which is cultivar-dependent. Ethylene is thought to function as a plant hormone responsible for coordinating and initiating ripening events in climacteric fruit (BAPAT et al., 2010; ALEXANDER and GRIERSON, 2002). It triggers the processes of ripening and senescence. The main consequences of this behaviour are a reduced shelf life and a decrease in the quality parameters, such as skin and mesocarp colour changes, autocatalytic ethylene production, chlorophyll degradation, sugar accumulation, occurrence of decay and fruit so ening (TRAINOTTI et al., 2007; GIOVANNONI, 2001). The latter is critical for the plum fruit industry, as it directly dictates fruit shelf life and quality (VALERO et al., 2007). There is a lack of reference data for diff erent varieties, particularly for European plums (USENIK et al., 2008). The plum fruit is highly perishable. Ripening, so ening and deterioration of the plum fruit a er harvest, which results in their short shelf life at ambient temperature, occur very quickly (MENNITI et al., 2004). Therefore, they require special care during handling and storage (ABDI et al., 1998). As part of the senescence process, the over-ripe stage of 134 J. Kožiskova, J. Golias a climacteric fruit is considered to be when the fruit loses part of its marketable characteristics, such as texture, colour and fl avour. According to CRISOSTO et al. (2004), plums with fl esh fi rmness below 9 and 13 N are considered to be in the over-ripe stage, hence commercially unmarketable. The change in fruit fi rmness has been a reliable parameter for measuring ripening changes (KADER, 2002), since it correlates to ethylene production (KHAN and SINGH, 2007). The management and control of fruit ripening is important for the successful transport and marketing of fresh fruit. An increased shelf life period could be useful for improving distribution and could favour long-distance transport. Today, the extended availability of seasonal fruit in the marketplace is commonplace thanks to both postharvest technologies and fruit varieties that allow for longer periods of storage. Each season, consumers increase their requirements and demand higher quality products. Flavour is remarkably important among the attributes consumers use to assess fruit quality. The purpose of this study was to evaluate the physicochemical changes in 13 plum cultivars during their ripening and over-ripening stages. The fruit were harvested at the ripe stage and ripened at ambient atmosphere and room temperature for a period of 7 days. From a traditional fresh market point of view, studying the over-ripening stage may not be of practical interest since the fruit is commercially unmarketable. However, the focus is mainly on the amount of ethylene being synthesized. The aim of this study is to analyze the infl uence of maturation on measured quality changes in European (Prunus domestica L.) plums and to fi nd any correlations between the measured parameters. This research also helps to reveal aspects that may help to explain some of the physiological diff erences among the varieties being evaluated. For this purpose, experiments were carried out on 13 plum fruit cultivars with diff ering climacteric behaviour. MATERIALS AND METHODS