Available online at http://journal-of-agroalimentary.ro Journal of Agroalimentary Processes and Technologies 2019, 25 (2), 51-58 Journal of Agroalimentary Processes and Technologies _______________________________________________ Corresponding author: e-mail: maria.iancu@ulbsibiu.ro Influence of enzymes action on chromatic characteristics and aromatic profile of pre fermented grape juice Maria-Lidia Iancu 1* , Ovidiu Tița 1 , Anca–Maria Stoia 1 1 "Lucian Blaga" University of Sibiu, Faculty of Agricultural Sciences, Food Industry and Environmental Protection, Department of Agricultural Sciences and Food Engineering, 5-7, Ion Raţiu Street, Sibiu, 550012, Romania .____________________________________________________________________________________ Abstract Was tested the limit of perception, the amplitude of the aromatic profile on nine flavor descriptors and the chromatic characteristics for the liquid obtained from white and black grapes, table varieties, which were processed by the action of the enzymes which acted as pectin lyase, pectin esterase, polygalacturonase, hemicellulase, in the form of enzymatic preparations of known action. The chromatic features were highlighted by means of the spectrophotometric technique with optical density measurements in the UV/Vis range and calculating color intensity and hue. The odorants were identified by sensory analysis with the development of the aromatic profile. Although only the Lallzyme EX-V enzymatic preparation has been recommended for the improvement of the chromatic properties, others such as Lallzyme HC (for clarification) and Rohavin Clear (for clarification) have contributed to changing the color perception of pre-fermented juices. They were highlighted the following flavor descriptors: a (fruit, apple, wax), b (citrus, floral, lemon, wax, magnolia), e (lilac, citrus, floral, woody); f (mint, cold, woody), h (sweetish, fruit tutti frutti). The highest values in the intensity of the perception of the flavor components were obtained in the Rohavin Clear variant and ranged between 2.4 and 2.5 out of maximum 3 points, thus proving a synergistic action of the pectinase and the polygalacturonase. Keywords: grapes, pectinolytic enzymes, UV/Vis spectrophotometer, pre-fermented juices, ODE (odor description) ______________________________________________________________________________________ 1. Introduction Since ancient times, natural enzymes produced by microorganisms have been used to process grapes. Nowadays, enzymes from exogenous sources are widely used in different industrial processes. Pectinases are used in making fruit or vegetable juice, in the wine industry, for treating wastewater, or in extracting vegetable oil [1-3]. The enzymatic hydrolysis is the most appropriate technique to generate color and flavor precursors in grape juice and then wine [4]. The color and the flavor components of the grape juice are given by the chemical substances that form the precursors for the same characteristics in wine as well [5]. The color and the flavor components of the grape juice are given by the chemical substances that form the precursors for the same characteristics in wine as well [6]. An important role in the extraction of flavor and color components is played by the use of exogenous enzymes in the form of enzymatic preparations. Their action is to release flavonoids, tannin, anthocyanins from the cells of the tissues from the skin of the grain and its vicinity. The preparations with similar activity in winemaking [7] are also used for juice production [8]. There are two categories of commercial preparations that contain clarification enzymes and color extraction enzymes.