Evolution of flavonols during Merlot winemaking processes

Identification of specific analytical fingerprints associated to grape variety, origin, or vintage is of great interest for wine producers, regulatory agencies, and consumers. However, assessing such varietal fingerprint is complex, time consuming, and requires expensive analytical techniques. Voltammetry is a fast, cheap, and user-friendly analytical tool that has been used to investigate and measure wine phenolics.

In a collective marketing strategy, the Protected Designation of Origin (PDO) can be used as a quality indicator. To highlight terroir specificities, it is useful to know how the wines are positioned on the local, national or international market from a sensory point of view. This is especially true for a comparison of varietal wines (e.g. Sauvignon blanc). We focus on the case of two closed Loire Valley PDO (France): Quincy and Reuilly. Three distinct tastings were organized. Firstly, at the local level comparing the 2 PDO (11 and 9 wines, 17 professional assessors); secondly at a regional level adding 3 closed PDO: Menetou-Salon, Sancerre and Pouilly-Fumé (3 wines per PDO, 16 assessors) and thirdly at an international level comparing these 5 PDO with Sauvignon Blanc wines coming from South Africa, New Zealand and Chile (1 to 3 wines per PDO, 19 assessors). All the wines were from the 2019 vintage and were considered to have a traditional elaboration process without contact with oak. A sensory descriptive analysis was performed using an aroma wheel allowing to combine a Check-All-That-Apply methodology, often used in sensory benchmarking, with a hierarchical structuration of the attributes. The aim is to facilitate data acquisition in a professional context without common training, to consider the hierarchical relationships among the attributes during the data analysis and to be able to characterize wines with a large range of sensorial variability. We use univariate, multivariate and clustering analyses. Similarities and differences between Quincy and Reuilly PDO wines and other Sauvignon blanc wines were identified. Specific attributes can distinguish the two PDO and different proximities exist with other local PDO, while clear differences were observed compared to international wines. Our study contributes to propose and discuss a method to do a wine sensory benchmarking highlighting sensory specificities linked to origin.

Study the influence of sample preparation methods on the volatile organic compounds (VOCs) profiling for fermentative beverages by GCxGC-TOFMS analysis. METHODS: Five common sample preparation methods were tested on pooled red wine, white wine, cider, and beer. Studied methods were DHS, Liquid-liquid extraction, mSBSE, SPE and SPME. VOCs were analyzed by GCxGC-TOFMS followed by data analysis with ChromaTOF. RESULTS: The volatile organic compounds (VOCs) profiling results were very dependent on the sample preparation methods.

The enzymatic browning of grape must is still a major problem in oenology today [1] being particularly serious when the grapes have been infected by grey rot [2]. Browning is an oxidation process that causes certain foods to turn brown, which often leads to them being rejected by consumers [3]. This is a particular problem in the case of wine, because grape must is very vulnerable to enzymatic browning [4].

AIM: Loop-mediated isothermal amplification (LAMP) [1] is a modern technology for fast and sensitive amplification of specific DNA sequences under isothermal conditions. Its simple handling and no need for dedicated equipment together with an evaluation of the amplification event by in-tube detection make this method advantageous and economically affordable for on-site investigations in the industry.