Textural Analysis of Muscadine Grapes, Poster Board #281

Muscadine grape (Vitis rotundifolia) berries have a relatively tough skin and a range of flesh textures from soft to firm.  Fourteen muscadine cultivars and selections and two Vitis vinifera samples were evaluated for berry texture using a TA-XT2i texture analyzer (Stable Micro Systems, Surrey, U.K.) equipped with a 2 mm cylinder punch.  Test speed was 1 mm/second and contact force was 1 g.  Berries were punctured at the equator and maximum force and deformation at first peak were recorded for 40 berries for each genotype.  The 2 mm cylinder punch demonstrated good separation of both within muscadine genotypes and between muscadine and vinifera table grape cultivars.  Deformation at first peak (DFP) represents the distance the probe moves from initial contact with the berry surface until the skin ruptures.  Maximum force (MF) represents the maximal force recorded by the probe until skin rupture.  Ideal fresh market grape berry texture is generally considered to be a tender skin in combination with a crisp flesh.  A tender skin would be represented by a low MF and a crisp flesh would be represented by a small DFP.  DFP varied nearly two fold among muscadine genotypes.  The highest DFP occurred among genotypes like ‘Cowart’, GA 5-1-28, and ‘Nesbitt’ with soft pulps similar to Vitis labrusca berries.  The lowest DFP occurred among UGA selections and releases like ‘Lane’, GA 6-1-219, and GA 4-3-147 which were selected for firm flesh.  Notably, GA 4-3-147 had a DFP similar to the vinifera table grapes.  Lowest MF among muscadine genotypes was recorded in GA 4-3-147 at nearly 8 N and highest MF was 12.5 N for ‘Nesbitt’.  However, even the lowest MF for the muscadine genotypes was still over twice that of the vinifera table grapes.  Texture analysis of muscadine showed a wide range for both DFP and MF.  Selections chosen for firm flesh resulted in DFP similar to vinifera table grapes.  While there was good variation for MF among muscadine genotypes, much improvement still needs to be made to have skin tenderness comparable to vinifera berries.