Monitoring small-scale alcoholic fermentations using a portable FTIR-ATR spectrometer and multivariate analysis

The two most deadly viruses infecting and threatening the productivity of grapevines worldwide are leafroll and red blotch viruses. There is no cure for viral diseases other than roguing the symptomatic vines and replacing them with certified vines derived from clean, virus-tested stocks. Given that phloem plays a central role in virus infection, this study aimed to purge the virus by girdling the phloem of leafroll-infected vines at different phenological stages of infected grapevines. Phloem-girdling was performed on canes at veraison to varying regions between the proximal and distal clusters.

Anthocyanins and phenolic compounds play a crucial role in winemaking, contributing to the profile, flavor, color, texture, and stability of wine. Grape clusters, specifically Vitis vinifera L. cv. Grenache, were handpicked from a commercial vineyard sited in Tudelilla, La Rioja, Spain (42°18′ 52.26″, Long. -2°7′ 59.15″, Alt. 582 m) on five distinct dates from veraison to harvest during the 2015 season. Non-contact spectral measurements were conducted on intact grape berries using a VIS-NIR spectrometer operating in the 570 – 1000 nm spectral range under controlled laboratory conditions, positioned at a distance of 25 cm from the berries. The quantification of 16 anthocyanins and phenols in 120 grape clusters was performed using HPLC, established as the reference method for validating the spectral tool.

Winemakers are increasingly experimenting with new techniques, such as spontaneous fermentation, prolonged yeast contact, higher pH, minimal sulphur dioxid, filtration and clarification or oxidative ageing. Along with this, the risk of microbial spoilage increases, and so the off-flavour mousiness, long time underestimated, is becoming more frequent. Characteristic of the mousy off-flavour is the delayed perception after swallowing the wine. After a few seconds the flavour appears, reminiscent of a dirty mouse cage. There are three known compounds that cause mousy off-flavor: 2-ethyltetrahydropyridine, 2-acetyltetrahydopyridine, and 2-acetylpyrroline. Yeasts such as Dekkera/Brettanomyces and heterofermentative lactic acid bacteria like Lactobacillus hilgardii can release these compounds.

La place prépondérante que prend le Massif Jurassien en Franche-Comté confère à la région un caractère montagneux qui a orienté l’agriculture vers l’élevage laitier. Cette vocation pastorale marquée et de rudes conditions climatiques sont à l’origine de la production, attestée depuis l’Antiquité, d’un fromage de réserve pour la longue période hivernale. Cette tradition fromagère, liée à des prairies naturelles, a perduré jusqu’à nos jours. La qualité et la spécificité du produit actuel, le fromage de Comté, ont été reconnues dès 1952 par l’attribution d’un label et dès 1958, par la reconnaissance d’un périmètre d’appellation d’origine contrôlée, l’A.O.C. Comté (fig. 1).

Over the last few years a drastic reduction has been noted in the survival rate of vine cuttings in nurseries, as well as in young vineyards in the Western Cape Province of South Africa. The low average take percentages of young vines can be attributed to several factors, including fungal, bacterial and viral diseases, insect and nematode pests,