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  • Author or Editor: Aislinn Mumford x
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Near infrared (NIR) spectroscopy can be applied to nondestructively assess soluble solids concentration (SSC) of ripening, physiologically mature ‘Geneva 3’ kiwiberries (Actinidia arguta). Spectrographic signatures were captured using a handheld NIR produce quality meter to build predictive models of internal fruit quality for ‘Geneva 3’ kiwiberries that had been held under cold storage (CS) conditions (0 to 1 °C, >90% relative humidity) as well as those not subjected to CS. The CS model, constructed using scans of 133 berries following 4 to 6 weeks in CS, predicts SSC using NIR wavelengths in the range of 729 to 975 nm. A total of 507 berries fresh from the vine were used to construct a predictive model for SSC of non-CS fruit using the same wavelength range. In each case, model predictive performance was investigated using split-half cross-validation, resulting in mean absolute error (MAE) values of 1.2% and 0.8% SSC for the CS and non-CS model, respectively. Each full model was then used to predict SSC of kiwiberries subjected to the alternative CS condition. The non-CS model maintained a low MAE (1.6% SSC) when applied to CS fruit, but the MAE of the CS model applied to non-CS fruit rose considerably (4.5% SSC). The performance of a combined model was tested against both CS and non-CS models, and a benefit to using tailored, CS-specific models was found, particularly in light of cross-seasonal results. As it has proven in many crops, NIR spectroscopy appears to be a promising tool for nondestructively assessing SSC in ‘Geneva 3’ kiwiberry fruit, with accuracy being enhanced by training models specific to postharvest regimes and/or defined ranges of SSC.

Open Access

Maturity at harvest is an important determinant of fruit quality in kiwiberry [Actinidia arguta (Siebold & Zucc.) Planch. ex Miq.], a climacteric fruit that is harvested after reaching physiological maturity but not yet ready-to-eat ripeness. Although a recommended cultivar for commercial kiwiberry producers in the northeastern United States is ‘Geneva 3’, no published research exists regarding recommended harvest and postharvest practices for this variety. In this study, conducted across two seasons, ‘Geneva 3’ kiwiberries were harvested at a range of mean maturities (6.5, 8.0, and 10.0°Brix), held in cold storage for various durations (4, 6, and 8 weeks), and then ripened at room temperature. At regular time points during ripening (0, 3, 6, 9, and 12 days), visual quality was assessed, and measurements were taken of soluble solids content, dry matter content, and firmness as a means of characterizing fruit quality. Results show that berries harvested at 6.5°Brix largely became visually unacceptable under cold storage conditions and resulted in lower overall quality fruit. Harvesting at 8.0°Brix resulted in high-quality fruit amenable to cold storage, and such quality was not enhanced by delaying harvest to 10.0°Brix. Fruit harvested at 8.0°Brix after 4 weeks in cold storage was found to be acceptable for consumption for, on average, a 3-day window after ripening at room temperature for 4 days. After 6 weeks in cold storage, the consumability window shortened to ∼2 days, starting after 3 days of ripening at room temperature. After 8 weeks in cold storage, the fruit were found to be largely visually unacceptable for fresh eating. In summary, the results indicate that harvesting ‘Geneva 3’ kiwiberries at 8.0°Brix produces berries with the greatest storability (at least 6 weeks in cold storage), the longest window of peak consumability, and the highest overall quality, while mitigating the risks associated with leaving physiologically mature fruit to ripen further in the field.

Open Access