Genetic variation in sugar composition among muscadine, Florida hybrid bunch and bunch grape genotypes

Sheikh M Basha,¹ Hemanth KN Vasanthaiah,¹ Devaiah M Kambiranda,¹ Kokila Easwaran,² Gilbert Queeley<sup>3

1</sup>Center For Viticulture and Small Fruit Research, Florida A&M University, Tallahassee, FL, USA; ²Centre for Plant Molecular Biology, Tamil Nadu Agricultural University, Coimbatore, India; ³Cooperative Extension, College of Engineering Technology and Agricultural Sciences, Florida A&M University, Tallahassee, FL, USA

Abstract: Sugar content and composition of the bunch grape (Vitis vinifera) berry and its hybrids has been investigated extensively while limited information exists on the sugar content and composition of muscadine (Vitis rotundifolia) grapes. In this study, selected commercial grape cultivars belonging to muscadine, bunch, and Florida hybrid bunch market types were studied for content and composition of sugars in ripe berries for 2 consecutive years. Berry sugars were analyzed by high-performance liquid chromatography (HPLC), and the amount of sucrose, glucose, and fructose was quantified based on their peak area. Glucose and fructose were the predominant sugars in berries of bunch, and Florida hybrid bunch grape genotypes and were present in almost equal amounts. In contrast, the muscadine berry contained sucrose, glucose, and fructose. Sucrose was not detected in bunch and Florida hybrid bunch grape genotypes. Glucose constituted 46.0%–53.0% of the total berry sugars while fructose ranged between 47.0% and 53.0% among the bunch cultivars studied. In Florida hybrid bunch cultivars, the glucose percentage varied from 39.0% to 56.0% while fructose varied from 44.0% to 53.0%. In muscadine genotypes, sucrose constituted 17.0%–47.0%, glucose 27.0%–39.0%, and fructose 26.0%–47.0%. The proportion of glucose and fructose was almost equal in all three categories while the level of sucrose varied widely among the muscadine genotypes indicating that variable sucrose accumulation and/or hydrolysis may influence the berry sucrose content among the grape genotypes.

Keywords: grapes, HPLC, sugars, sucrose, glucose, fructose, statistical analysis