Italy: Kiwi storage prediction

Kiwis (Actinidia deliciosa) are harvested raw and stored in refrigerated units until they are ripe and ready for consumption. During this period, they undergo two transformations - their flesh softens and amid turns into sugar, i.e. total soluble solids measured in Brix degrees.

The total soluble solid concentration is deeply connected to sweetness, organoleptic qualities and the enjoyment of consumers. Most of them prefer Hayward kiwis with a sugar level above 14° Brix.

Flesh firmness is an important indicator of post-harvesting shelf-life. In New Zealand, the minimum firmness must be 9.81 N to guarantee a reasonable shelf-life and enable transport to different markets.

According to a study published on 6th January on the online Journal of Food Engineering, predicting the total soluble solid concentration and flesh firmness with non-destructive techniques such as VIS-NIR spectroscopy would enable the strategic marketing of kiwis.

Researchers from Massey University (New Zealand) assessed the accuracy of visible-near-infrared (VIS-NIR) spectroscopy upon harvesting (data input) to predict total soluble solid concentration and flesh firmness after 5 months of storage (data output) using the Blackbox model.

"Although these models enables us to predict total soluble solid concentration and flesh firmness, the accuracy is not as yet useful for the processing line, especially for what concerns sorting, as we still have to work on reducing the prediction error," explain the researchers.

Source: Mo Li, R.R. Pullanagari, T. Pranamornkith, I.J. Yule, Andrew East, 'Quantitative prediction of post storage 'Hayward' kiwifruit attributes using at harvest Vis-NIR spectroscopy', 2017, Journal of Food Engineering, doi: 10.1016/j.jfoodeng.2017.01.002, www.sciencedirect.com/science/article/pii/S026087741730002X