Metatartaric acid instability

Metatartaric acid instability accounts for initially surprising observations concerning wines treated in this way. One sample, stored at 0°C in a refrigerator, had no precipitation, while calcium tartrate precipitation occurred in another sample stored at 20-25°C when it was no longer protected due to hydrolysis of the metatartaric acid. 

Other methods to achieve bitartrate stability, rarely used in the North Coast, are addition of metatartaric acid, electrodialysis, reverse osmosis, and ion exchange. Concern with potential bitartrate instability varies from winery to winery. Some enologists prefer to keep the processing of wine to a minimum. They rely solely on cool fermentation and winter storage temperatures to precipitate excess bitartrates. They trust their customers will overlook any additional bitartrate crystals that precipitate out in bottled wines. 

With this in mind, its effectiveness has been compared to that of two other tartrate stabilization methods continuous contact cold stabilization and the addition of metatartaric acid (Table 1.21). This comparison was carried ont by measuring spontaneous crystallization after the addition of KHT (Section 1.6.4). The values obtained indicate the effectiveness of protective colloids, even if they do not necessarily correspond to the instability temperatnres. The addition of 15 g/hl of Mannostab to wine 2 and 25 g/hl... 

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