823–831. Crop Post-Harvest: Science and Technology

247 Crop Post-Harvest: Science and Technology , First Edition. Edited by Debbie Rees, Graham Farrell and John Orchard. © 2012 Blackwell Publishing Ltd. Published 2012 by Blackwell Publishing Ltd. 12 Kiwifruit, Guava, Passion Fruit and Lychee Graham Farrell The account presented here concentrates on recent findings and new initiatives in the post-harvest aspects of four commodities with important roles in an expanding market for exotic fruits and vegetables. General, comprehensive volumes on the post-harvest behaviour and handling of these fruits, inter alia, are given by Nagy and Shaw 1980, Morton 1987, Mitra 1997, Wills et al. 1998, Thompson 2003 and Gross et al. 2002. Warrington and Weston 1990 provide an in-depth study of all aspects of kiwifruit from a New Zealand perspective. KIWIFRUIT The genus Actinidia comprises about 50 species of kiwifruit, mostly from temperate forests in south-western China. The main commercial variety is Hayward Actinidia deliciosa A. Chev. C. F. Liang A.R. Ferg., preferred for its good storage characteristics over other varieties, but A. chinensis Planch. and the hardy kiwifruit A. arguta Sieb. Zucc. Planch. ex Miq. are also cultivated com- mercially. Kiwifruit has been an economic success mainly because of its good keeping qualities over long periods at 0°C Hewett et al. 1999. Mature fruits are broadly oval, green-brown in colour and densely covered with fine hairs. The pulp is bright green with a mass of small black seeds. Kiwifruit plants are vines with the fruits borne on long pedicels Cheah Irving 1997. Production Italy is the main producer of kiwifruit, followed by New Zealand and Chile Rushing 2002. California is the major producer in the United States, accounting for 95 of all kiwifruit produced nationally. Chinese production is forecast to increase rapidly, reaching about 0.5 million tons MT and accounting for half of world output by the end of 2006 Huang et al. 2004. Table 12.1 shows some production figures by region. Harvesting Kiwifruit are nonclimacteric and are among the few fruits that retain large amounts of starch at maturity. Hydrolysis of starch continues after harvest even at low temperatures and is complete a few weeks later, when the starch is converted to soluble sugars mainly glucose and fructose, with some sucrose. At the limit of carbohydrate accumulation kiwifruit will have reached the best quality for consumption and so delays in harvest will not further improve the flavour Strik 2000. In the past, maturity was based on arbitrary harvest dates, fruit colour or firmness but these characters are not good guides to maturity. However, firmness is used in the United States, with a minimum force of 6.4 kg, using a penetrometer with an 8 mm tip, considered appropriate, together with a minimum soluble solids content SSC of 6.5 Crisosto et al. 1999. Penetrometer readings should be taken on fruit at 37–39°C Crisosto 1997. In New Zealand, measurement of firmness using a noncontact laser air-puff method has been described by McGlone and Jordon 2000. Positive correlations between SSC and fruit maturity and eating quality have been established, and so refractometer