Page 11 - Grapevine Sept-Oct 2019
P. 11

In The Winery

            is the case, it is best to “quarantine” that particular   collect a representative sample.  The surface of the
            lot of wine until the proper blending time making    wine may have a lower SO2 reading and false num-
            sure not to infect other batches.                    bers other than these that do not reflect the major-
                                                                 ity of the wine.  Please keep in mind this sampling
              The author wants to emphasize for the purpose      choice could be a large source of cross-contamina-
            of this article the lab test results are correct and   tion if not done properly because certain items may
            the lab technicians are not at fault.  The numbers   contact each wine as samples are collected.
            reflect the sample given to the lab but the sample
            is not representative of the complete batch of wine    Ball Valves: Known to be the largest offender of
            in that tank.  Take the opportunity to resample a    panic and false a test results from the lab.  Ball
            wine that shows suspicious numbers in the lab.       valves often have high spoilage counts, if not
            Remain open-minded and always quiz yourself to       cleaned properly, lending toward off values most
            the possibilities of improper sampling.              particularly with Volatile Acidity and Sulfur Dioxide
                                                                 just to name two.  Other tests may give false
              Below are some pointers to help with the scope of  reports in terms of the tank’s actual contents.  One
            sampling properly                                    should flush ball valves diligently when taking sam-
                                                                 ples and one should be able to clean these valves
                             Tank Sampling                       well while not in use.

              Sample Valve: Perhaps one of the easiest situa-      Butterfly Valves: These offer an excellent source
            tions to monitor a large quantity of wine, yet, this   to sample a tank’s contents if a sample valve is
            process must be taken seriously with particular      not present.  Care should be taken to flush these
            attention to the contents.                           valves, too.  This flushing is more to remove solids
                                                                 and less to remove any potentially spoiled wine.
              If taking a sample from a stainless tank under-    The butterfly valve often will collect solids in them
            stand where the sample is coming from in ref-        and deliver an unrepresentative sample unless
            erence to the contents of the tank.  If a cloudy     flushed prior to sampling.
            sample is taken from a sample valve near the bot-
            tom of the tank, understand it may not be cloudy                      Barrel Sampling
            throughout the whole tank and most likely very
            clear at the top of the tank.  Was the sample valve     This is often the easiest yet most winemakers
            cleaned after it’s previous use?  Was the valve      try and dodge this exercise making large decisions
            flushed of its spoiled contents to bleed off any high   after tasting one barrel in a particular batch.  One
 Sample Your Juices & Wines   VA or bacterially loaded wine, prior to sampling,   needs to isolate the vessels of a certain lot of juice
            that may have formed in the unsealed body of that
                                                                 or wine.  With proper record keeping and a logical
            valve?  This flushing action of the sample valve, due  marking of each container this process is not too
 By: Thomas J. Payette, Winemaking Consultant
            to the positive pressure in the vessel, has little risk   bad.  One may sample an equal portion from each
            for cross-contamination and it is recommended        vessel of a particular lot (recommended for blend-
            in order to obtain a representative sample of the    ing session exercises) or fifty percent of the vessels
            tank’s contents.                                     for that lot.  Many times the winemaker can hedge
                                                                 this knowing a particular test or cellar action will be
              From the top lid or manhole: Perhaps one of the    run in the future.  One could use the fifty percent
            best ways to sample in well managed cellars if all   rule, or even less, if only addressing minor actions.
            the tanks are kept topped up and a catwalk exist to   Knowing the wine will be racked from barrel in 6
            each man way.  This gives the winemaker a chance     months may lend toward running further tests,
            to visually inspect the wine tank contents while tak-  double checking current data and making larger
            ing the sample.  Caution should be expressed not to  corrections at that time if needed.
            sample the surface of the wine but to get the col-
            lection flask well under the surface of the wine to     Stratification: If taking a sample from the very top

            877-892-5332                  The Grapevine • September - October 2019                            Page 9
   6   7   8   9   10   11   12   13   14   15   16