Extension of Shelf-life by Limited Duration of Propylene and 1-MCP Treatments in Three Kiwifruit Cultivars

Abstract

In order to extend the "eating window", the optimum ripening phase suitable for eating, the combination of treatment with propylene (an ethylene analog) and 1-methylcyclopropene (1-MCP; an ethylene inhibitor) was assessed in three kiwifruit cultivars: 'Rainbow Red' Actinidia chinensis, 'Sanuki Gold' A. chinensis, and 'Hayward' A. deliciosa. Propylene treatment initiated the ripening process by inducing fruit softening, increasing soluble solid content (SSC), and decreasing titratable acids (TA), with or without endogenous ethylene production, depending on the duration of exposure. Once endogenous ethylene was induced, it accelerated fruit ripening, resulting in an over-ripening phase and shortening of the "eating window". 'Rainbow Red' and 'Sanuki Gold' fruit treated with propylene continuously or for 48 h initiated endogenous ethylene production that led to an "eating window" lasting only 2 days (range of 3-5 days after the start of treatment), whereas it lasted for 7 days (range 3-10 days) in 'Hayward' fruit. Limited propylene treatment of the three cultivars for 24 h induced ripening without the detection of ethylene production, suggesting that the optimum ripening phase suitable for eating can be attained without endogenous ethylene production, resulting in a longer "eating window". 'Rainbow Red' and 'Sanuki Gold' fruit treated with propylene for 48 h followed by 1-MCP treatment had extended "eating window" and shelf-life, with the suppression of endogenous ethylene. These results illustrate the practicability of different durations of propylene treatment in facilitating kiwifruit ripening and the additional benefit of 1-MCP treatment to the extend shelf-life of new high-quality kiwifruit cultivars, 'Rainbow Red' and 'Sanuki Gold'.

Characterization of Ripening-related Genes Involved in Ethylene-independent Low Temperature-modulated Ripening in ‘Rainbow Red’ Kiwifruit during Storage and On-vine

“…The fruit have a high SSC of >18% and a TA of ~1% making it a premium cultivar (Asiche et al, 2016;Murakami et al, 2014). Gradual softening of 'Rainbow Red' fruit during low temperature storage has been previously reported (Asiche et al, 2018;Murakami et al, 2014).…”

“…Fruit firmness was measured as previously described (Asiche et al, 2016;Mworia et al, 2010) using a penetrometer (model SMT-T-50; Toyo Baldwin, Tokyo, Japan) fitted with a 5 mm plunger at a speed of 30 mm·min −1 ). SSC was measured from juice extracts using a digital refractometer (Atago Co. Ltd, Tokyo, Japan) and expressed as brix (%).…”

“…The major postharvest problem in kiwifruit handling is the incidence of ripening rot caused by Botryoshaeria spp., Phomopsis spp., and Diaporthe actinidia (Kinugawa, 2000;Koh et al, 2005;Manning et al, 2016;Yano and Hasegawa, 1993). Infected fruit produce disease-induced ethylene that triggers a perceived climacteric-type ripening in healthy adjoining fruit (Asiche et al, 2016). Therefore, low temperature storage is used to extend kiwifruit storage life since it reduces the incidence of ripening rot (Arpaia et al, 1987;Pranamornkith et al, 2012).…”

“…Generally, fruit are classified as either climacteric or nonclimacteric based on the presence or absence of a marked rise in respiration and ethylene production during ripening as well as their response to exogenous ethylene (McMurchie et al, 1972). Kiwifruit are considered climacteric fruit since exogenous ethylene accelerates fruit ripening characterized by softening, a decrease in titratable acidity (TA), an increase in soluble solids content (SSC), and development of aroma (Antunes et al, 2000;Asiche et al, 2016;Mworia et al, 2010;Pratt and Reid, 1974).…”

Effect of Storage Temperature on Fruit Ripening in Three Kiwifruit Cultivars

“…Fruit were exposed to room temperature for 2 h before assessment. Fruit skin was sliced off from two opposite cheeks along the equatorial region and outer pericarp firmness was subsequently measured using a penetrometer (model SMT-T-50; Toyo Baldwin, Tokyo, Japan) fitted with a 5-mm plunger (Asiche et al, 2016). The SSC of the fruit juice was determined using a digital Atago PR-1 refractometer (Atago Co. Ltd, Tokyo, Japan) and expressed as Brix (%).…”