Identification of Aroma Volatile Compounds In Juice of California-grown Pomegranate Cultivars

The pomegranate (Punica granatum) is one of the oldest cultivated fruits as well as richest in history and folklore. Its juice becomes the base for sauces and flavorings for drinks, savory dishes, and sweets due to pomegranate arils´ fruity and sweet characteristics. Pomegranate-rich diets have been demonstrated to help protect the brain, cardiovascular and central nervous system, reduce type 2 diabetes etc. based upon demonstrated anti-inflammatory, anti-carcinogenic and anti-mutagenic characteristics. This has led to a remarkable surge in production and consumption of pomegranate products. Recently, increased consumer awareness of the health benefits of consuming phytonutrient-rich fruits, and keen marketing, has created demand for juices and functional beverages containing pomegranate. However, there is little information concerning the aroma of juices from around the world. The aim of this work was to define the aroma profiles of pomegranate juice in selected cultivars from the germplasm program at the USDA in Davis, California. Cultivars were specifically chosen to represent high versus low in aril color, acidity, sugars/sweetness and astringency/bitterness. They included: ‘Haku-botan’, ‘Nikitski ranni’, ‘Wonderful’ (commercial), ‘Myagkosemyannyi Rozovyi’, ‘Fleischman’s’, ‘Salavatski’, ‘Sin Pepe’, ‘Nusai’, ‘Ovadan’, DPUN0081 ‘Wonderful’, and ‘Kara Gul’. Fruit were harvested in 2011, washed, dried, chilled (8 °C), individually wrapped, boxed carefully and transported overnight to the Food Processing & Sensory Quality, Agricultural Research Service, Southern Regional Research Center in New Orleans where they were mechanically pressed in a juice pilot plant. A DVB/Car/PDMS SPME volatile headspace extraction was accomplished with 10-ml juice and isoamyl isovalerate in 20-ml vials for 12.5 minute exposure at 40 °C, prior to injection into a HP6890/5973 GC-MS with a DB-5 column. Compounds were identified in triplicate runs by HP ChemStation software searched against the NIST, Wiley libraries and authentic standards. Preliminary analyses have identified ethanol, hexanal, 3-hexen-1-ol, 2-nonanone and alpha-terpineol to be recovered in the pressed whole-fruit juice in most of the different cultivars. Other compounds (e.g. different C₆ aldehydes and alcohols, pinenes, terpinolenes, isocineole, terpineols, limonene, linalool) which could help to distinguish the germplasm cultivars “uniqueness” and/or utility for juicing will be differentiated. A long-term goal is to determine important compounds in juices that have flavor importance, and conserve them during juice filtration and pasteurization.