Efficacy of instrumental measurements for determination of minimum requirements of firmness, soluble solids, and acidity of several apple varieties in comparison to consumer expectations

Firmness, soluble solids content and acidity are important factors determining eating quality of apples. Tests with consumers confirmed that acceptance can be predicted by instrumental measurements of total soluble solids (refractometer), titratable acidity and firmness measurements for some apple varieties. 'Golden Delicious' of acceptable eating quality should attain a minimum of 12degrees Brix for total soluble solids, a minimum acidity of 3.2 g/l (malate) and a minimum reading of 44 N for firmness. For Elstar firmness should exceed 46 N and soluble solids should be above 12degrees Brix. Elstar with acidity less than 4.0 g/l or high acidity (>6.5 g/l) were not liked by consumers. Firmness readings of 'Gala' should attain 56 N. However, acceptance by consumers of 'Gala' and 'Elstar' seemed less dependent on firmness, soluble solids content and acidity but dependent on aroma quality and juiciness. In this respect, future optimisation of storage should take aroma aspects into account. (C) 2002 Elsevier Science B.V. All rights reserved.