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62 practical winery & vineyard February 2015 w i n e m a k i n g ics (Phase 3). Given the physico-chemi- cal phenomena involved, it is clear that direct measurement of the quantity of oxygen supplied by the oak wood to a model solution is scarcely feasible. The experiment was repeated many times with stave fragments from the same piece of wood, and also with other wood samples. The example shown in Figure 1 corresponds to two staves from the same source. In this experiment, the stave was removed from the solution at the stage corresponding to maximum O 2 concen- tration. This was in order to evalu- ate only the speed of consumption of oxygen by the alcohol-water solution containing the oak wood extractives. In this way, we were able to make an initial approximation of the average balance between the residual oxygen yielded by the wood and its consumption by phe- nolic compounds. We have shown that, under experi- mental conditions, the rate of oxygen consumption by the solution containing wood extractives (Phase 3) is between 20 and 30 µg/L per day. These values are low compared to the average rate of oxygen dissolution observed during the first days of maceration (Phase 1) that approaches 300 µg/L per day for the OENOBLOCKs in infusion bag. same staves. In the example of the use of staves, and of barrel alternatives in general, the extraction is rapid because it takes place simultaneously in three directions across the oak vessels: radial, tangential and longitudinal. Given the preliminary results, it became evident that the rate of oxy- gen consumption by the phenolic com- pounds yielded by the wood could interfere with accurate assessment of the quantity of oxygen supplied by the wood. For this reason we optimized the maceration conditions so as to minimize the consumption of oxygen by these compounds. This step allowed us to obtain a linear, replicable method, i.e. the quantity of oxygen measured (maxi- mum O 2 ) is proportional to the number of staves macerated. Influence of anatomical structure of the wood and toast "Grain" is a term used by coopers to describe the average width of growth rings, and in consequence the growth rate of a tree. They traditionally make reference to two "standards" to define grain type: Limousin oak with quick growth (4 mm or more), large structure for "coarse grain;" and Allier oak with R E G I S T E R T O D AY WWW.CRAFTBEVERAGEEXPO.COM We offer a Special Rate for artisan wine producers like you.