Effect of storage time and temperature on the volatile composition of Malvasia diCandia Aromatica white wine by GC×GC-MS

The within-variability of the vineyard affects the grape composition, including sugars, acids, aromacompounds, and polyphenols; therefore, it strongly influences the sensory and chemical characteristics of thewines [1]. In this scenario, precision agriculture techniques and selective harvesting are powerful tools tomanage vineyard variability and to enhance the sustainability of the winemaking process and the quality ofwines [2]. This study aimed to assess the effect of vine vigor (high and low), time, and storage temperature onthe aroma profile of Malvasia di Candia Aromatica white wines from Piacenza’s province hills.In our trial, the vineyard vigor map was obtained through MECS-VINE sensor [3], then translated into aprescription map with which the grapes were harvested by a vigour-selective mechanical harvester (NH Braud9080L with Enocontrol system, Italy). For each vigour zone (Low Vigor, LV; High Vigor, HV; Control, C) 30kg of grape were collected, immediately pressed and fermented at 14°C. At the end of alcoholic fermentation,the wines were bottled in dark glass and stored for 6 months at 5°C; 15°C and 25°C. The wines were sampledat 0 days (T0), 90 days (T1) and 180 (T2) days and the volatile organic compounds (VOCs) were analyzed byHS-SPME-GC×GC-qMS (Shimadzu, Italy) equipped with a 1D SLB-5ms apolar column and a 2DSupelcoWAX polar capillary column. VOCs were identified by matching with NIST20 libraries and the linearretention index. The data analysis (ANOVA, PLS-DA, Fold Change Analysis) was performed byMetaboAnalyst platform. A pool of 112 volatile compounds was quantified in experimental wines, amongthese: 63 terpenes, 5 norisoprenoids, 34 esters, and 5 higher alcohols. At T0, the LV wines showed higherconcentrations of terpenes compared to HV and C wines. The most relevant compounds in terms ofconcentration were Linalool, Geraniol, and L-α-Terpineol that were detected at significantly higherconcentrations in LV. In order to evaluate the effect of time and temperature of storage the dataset was run witha PLS-DA statistical model, the variable importance in projection (VIP) analysis was used, and then coupledwith Fold Change analysis (FC). For the storage time, the most characterizing compounds were mainlyterpenes that were mainly down-accumulated over time (e.g., trans-Geranylacetone, trans-Nerolidol, α-Pinene,trans-2-Pinanol, and Linalool). On the other hand, for storage temperature, more heterogeneous results wereobtained: both terpenes and esters characterized the modification of the aromatic profile and were both down-and up-regulated. Among terpenes, a general reduction of Linalool and Geraniol, and the increase of theiroxidated and derivates forms were detected (e.g., Linalool 3,7-oxide, Nerol oxide). Relevant up-regulationwere also detected in charge of TDN and TPB,1. The obtained preliminary data confirmed the expecteddifferences in aroma composition among wines coming from different vigour zone, especially for thedifferences highlighted by terpenes [2]. According to the data, the aroma compounds follow literature availablepatterns, especially when stored for a long time at higher temperatures [4].References1. Smart, R. E., et al. "Canopy microclimate modification for the cultivar Shiraz. I. Definition ofcanopymicroclimate." Vitis 24.1 (1985): 17.2. Bramley, R. G. V., J. Ouzman, and Paul K. Boss. "Variation in vine vigour, grape yield and vineyard soils andtopography as indicators of variation in the chemical composition of grapes, wine and wine sensory attributes."Australian Journal of Grape and Wine Research 17.2 (2011): 217-229.3. Gatti, Matteo, et al. "MECS-VINE®: A new proximal sensor for segmented mapping of vigor and yieldparameters on vineyard rows." Sensors 16.12 (2016): 2009.4. Slaghenaufi, Davide, and Maurizio Ugliano. "Norisoprenoids, sesquiterpenes and terpenoids content ofValpolicella wines during aging: Investigating aroma potential in relationship to evolution of tobacco andbalsamic aroma in aged wine." Frontiers in chemistry 6 (2018): 66.