Sealing the Bottles

It has been suggested that containers made of clay (e.g., the amphora of the bronze age) were adopted for use during the thousands of years of winemaking that preceded the ability to produce suitable glass vessels. Sealing the amphora, as reported by archeologists and historians, was accomplished with clay or leaves covered with clay, rags, wax, pine resin (producing retsina), and even today’s popular choice, cork. With the exception of the latter, where only a small amount of air can leak in, it appears that too much air would enter and the flavor of the wine would change. In part, the effort to seal the amphora was futile, as the clay amphora would leak too. But waxes and resins helped seal out air and, in the process, often changed the flavor of the beverage. Again, historically, it appears from analysis of the contents remaining in the old vessels that various flavoring agents, such as berries, fruits, leaves, flowers, and even metals such as lead were intentionally added to wines to suit the tastes of the consumer. Nonetheless, oxidation and bacteria (e.g., Acetobacter aceti, known to convert ethanol [CH3CH2OH] to acetaldehyde [CH3CHO] and thence to acetic acid [CH3CH2OH]) would often make the beverage unpalatable (by today’s tastes). So, tastes were adjusted to fit the beverage available! It was also found that wines that had additional ethanol present were resistant to bacterial action, so tastes (even into the twentieth century) were developed for “fortified” wines (vide infra, Chapter 21) such as Port, Sherry, and Madeira that were to be shipped in casks. More recently shipment of the latter in glass bottles (since late in the nineteenth century) along with cork stoppers have become common. Most recently, synthetic (i.e., polymer) stoppers and aluminum screw caps have been used for all of these beverages because most wine is produced to be consumed within a few years of its bottling. This fairly recent change has arisen as an accommodation to large-scale production, long-distance shipping, and storage in commercial sales facilities, none of which encourage saving wine for aging.