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Keywords:

  • canning;
  • color;
  • freezing;
  • genotype;
  • jam;
  • strawberries

ABSTRACT:  This investigation was to evaluate fruit color and study the effect of processing on color quality of strawberry products. Three color instruments with different viewing angles, viewing areas, and sample presentation geometries were compared for their effectiveness in measuring CIEL*C*ho color values for fresh fruits of 6 strawberry genotypes. There were significant differences between genotypes as well as between instruments. Fruits from the Totem genotype were frozen, canned, and made into jam. Color changes were measured along with the following compositional determinations: total monomeric anthocyanins (ACN), total phenolic content (TPC), and percent polymeric color. ACN in fresh strawberries ranged from 37.1mg to 122.3 mg per 100 g of fresh fruit. Freezing resulted in an apparent increase in ACN and transfer of 70.2% of the anthocyanins from the berries into juice. Physical transfer of pigments to syrup also occurred with canning: there was approximately 70% loss in ACN, about 20% increase in polymeric color, and 23.5% decrease in TPC. Pronounced color change and substantial losses in ACN and TPC of strawberry jams occurred during processing and 9 wk of storage. Storage of jams at 38 °C compared to 21 °C over a period of 9 wk resulted in marked losses of ACN and TPC.