This is a final research report from Hort Innovation’s historical archives. Please note that as these reports may date back as far as the 1990s, the content and recommendations within them may be superseded by more recent research.

What was it all about?

SmartFresh [a.i. 3.3 per cent 1-methylcyclopropene (1-MCP)] previously known as EthylBloc could block the action of ethylene in harvested fruit and vegetables. Ethylene is a natural fruit ripening hormone. Therefore, SmartFresh could be extremely useful as a post harvest treatment to extend the storage life of strawberries.

A series of experiments were conducted in 2001 using strawberry cv. Selva fruit picked in Autumn and late Spring/early summer, to evaluate the potential of SmartFresh to extend the storage life of strawberries. SmartFresh was used at the concentration range of 15 to 2000 parts per billion (ppb) for 2 to 4 hours and applied to pre-cooled fruit (2.5°C pulp temperature) and warm (15°C pulp temperature) fruit. The fumigation room temperatures were 2.5°C and 20°C respectively.

In general, SmartFresh did not have a significant effect on the storage quality (firmness, colour, gloss) of strawberry cv. Selva, compared to fruit not treated with SmartFresh over a storage period of 2 to 9 days at 5°C. However, there were some exceptions to this. For example, the firmness of fruit treated with 15 ppb 1-MCP in the absence of exogenous ethylene was significantly firmer compared to fruit not treated with Smartfresh.

Previous reports found that the level of rots in strawberries may have increased if the fruit was exposed to high concentrations of SmartFresh greater than 50 ppb. In this study, the incidence of rots was generally acceptable for up to 4 days and there was no significant effect of SmartFresh at concentrations ranging from 100 ppb to 2000 ppb on the incidence of rots. Rots were more a problem associated with picking damage and injuries associated with squeezing the fruit into punnets at packing. Rapid cooling after harvest significantly reduced the incidence of rots.

Improved objective quality assessment methods for strawberries were needed. Consumers wanted bright red berries with high gloss and free from rots and blemishes. However, visual assessments varied depending on who did the assessment. Researchers needed objective methods to remove the guesswork. Rots could be assessed visually because any level of rot is unacceptable, but colour gloss and firmness need to be assessed using objective measurements. Methods to measure objective quality assessments needed to be evaluated, to enable accurate measurement of changes in strawberry quality. Such measures could then be used by the strawberry industry to quantify strawberry quality.

SmartFresh did not significantly extend the storage life of strawberry cv. Selva. in the studies reported here. However, before it could be concluded that SmartFresh had no significant effect on the storage life of strawberries longer treatment times up to 24 hours needed to be tested. Furthermore, objective quality assessment methods needed to be developed to quantify strawberry fruit quality.