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  • Author or Editor: W. F. McClure x
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Abstract

The relationship of holding temperature and stage of ripeness to decay development of blueberries (Vaccinium corymbosum L) was determined comparing 6 sets of 5 ripeness classes (light-sorted; 740-800 nm) stored at 1.1°, 10.0°, and 22.2°C. On each of 6 dates, 1 set (3 temperatures × 5 ripenesses × 4 replications) was removed from storage and sorted for decay. Regardless of cultivar or stage of ripeness, all blueberries stored at 22.2° decayed rapidly (within 5 days). Only when the blueberries were held at 1.1° did the time and expense of light-sorting appear economically justifiable; i.e., overripe berries (% soluble solids (SS)/% acid (Ac) ratio = 30) required about 12 days while just-ripe blue fruits (SS/Ac = 10) required about 32 days to develop 20% decay. Estimates of maximum degree of ripeness (SS/Ac) for fresh marketing (< 20% decay at retail) were made: Trans-Atlantic (up to 20,) transcontinental (up to 27), and local (⋜ 1200 km) (up to 30). Fruit riper than SS/Ac = 30 should be processed within 24 hours.

Open Access

Abstract

Spectral curves of fresh berries of both bronze and black muscadine grapes representing a wide range of ripenesses were obtained with a multipurpose spectrophotometer at the Pioneering Instrumentation Laboratory of the U.S. Department of Agriculture at Beltsville, Md. Using these curves, wavelength-pairs of 546-610 nm for bronze and 740-800 nm for black grapes were selected. A Berrymatic (high-speed fibre-optic sorter) developed for sorting blueberries was fitted with pairs of narrow band interference filters of the above wavelengths. Several tests over a 2-year period indicated that both black and bronze grapes can be light-sorted according to ripeness, as confirmed by destructive analyses of pH, soluble solids and acids in the fruits. Berry size and orientations of the berry on the light-sorter with respect to the light path influenced readings.

Open Access