Instrumental Textural Analysis of Muscadine Grape Germplasm

Abstract

Twenty-six muscadine grape (Vitis rotundifolia Michx.) cultivars and selections were evaluated for a range of skin and flesh texture attributes. Two Vitis vinifera L. and one Vitis labruscana Bailey table grape cultivars were included for comparison. Penetration tests using a flat cylindrical probe were used to assess whole berry texture. Ideal whole berry texture is firm and easily broken down during mastication, which was measured as small berry deformation at first peak and berry maximum force, respectively. Muscadine berry deformation at first peak ranged from 4.35 to 7.82 mm and berry maximum force ranged from 5.7 to 13.9 N. V. vinifera table grape berries were firmer (3.14 to 3.19 mm berry deformation at first peak) and more tender (4.0 to 4.9 N berry maximum force) than muscadine berries. Berry penetration work was strongly correlated with both berry deformation at first peak and berry maximum force and ranged from 13.0 to 54.1 mJ in the muscadine germplasm. Penetration tests of muscadine berry flesh revealed a range of flesh firmness from very soft (0.65 N) to firm (3.06 N) but none was as firm as the V. vinifera berry flesh (3.9 N). Penetration tests of muscadine berry skins revealed newer selections bred for table use had relatively tender skins with a skin break force of 12.1 N, which was not different from V. vinifera samples. Berry penetration work and flesh maximum force were determined to be the most useful characteristics for routine screening of breeding program material.