Small and delicious - but does it store?
HortResearch scientists are working to find out more about the new grape-sized kiwifruit, Actinidia arguta. Storage and shelf-life capabilities are important factors in the future marketability of the sweet, bite- sized fruit.
Dr Elspeth MacRae and Linda Boyd have completed a KNZ-funded project to determine if a new arguta selection had similar storage and shelf-life properties if grown in different environments, and if storage and shelf-life responses were similar to those of the previous season.
The second objective was to determine the feasibility of harvesting the selection earlier in the season, rather than in the conventional manner when fruit first become soft. They wanted to find out if such fruit were able to store, have a good shelf-life and good flavour comparable to fruit harvested in the conventional manner.
Fruit maturity was monitored in vines growing at Te Puke Research Orchard. Once seeds in the fruit were all mature a subsample of fruit was harvested for storage. The remainder of the fruit from Te Puke, and Nelson, were harvested when one percent of fruit on the vine were ripe, ie. as in 1998. Fruit were stored for six weeks or eight weeks, followed by shelf- life determinations at 5 or 20oC. Some fruit were monitored for 12 to 16 weeks storage.
The results confirm the need to harvest this selection when one percent of fruit are soft. Fruit can be stored for eight weeks at 0oC and have three to four weeks shelf-life at 5oC. Fruit stored in a similar manner to the previous season, allowing at least eight weeks storage followed by three to four weeks shelf-life, if fruit were held in a chiller or refrigerator display unit. Pitting was the only storage problem and it was minor.
Fruit from Nelson and Te Puke were similar in storage response. Fruit from the first crop from a commercial orchard in Nelson softened slightly faster in storage, and to a lower fruit firmness, than the fruit from older vines in research orchards. Fruit harvested before one percent of the fruit on the vine were ripe (soft) did not store as well, and showed more storage defects and inferior flavour than fruit harvested when one percent were ripe.
"This means that it will not be possible to harvest fruit while all fruit are hard. Attention will need to be given to harvesting and handling procedures that can deal with the presence of soft and semi-soft fruit. These procedures are relatively labour intensive for industry and will need to be better streamlined," said Dr MacRae.
"It is recommended that future work on the selection concentrates on this aspect, and that further arguta selections of interest be compared for storage behaviour, using it as the benchmark."