A Scientist and His Hobby the TECHNOLOGY of WINE-MAKING

Conclusions Preliminary laboratory tests and later wind The thermal design study for a Pyroceram ra tunnel tests showed that the large compressive stress dome for a Mach 4 missile was successfully con at the point of the radome would not cause any ducted. Investigation of the effect on thermal stress structural problem. Finally, correlation of strain of blunting the radome disclosed that little or no gauge measurements made during wind tunnel tests reduction in maximum tensile thermal stress may be demonstrated that both the theoretical method expected with a 1.35-in.-radius nose. Thus, one used to predict temperature gradients and the cannot automatically assume that the increased cylindrical theory used to determine thermal drag caused by blunting is justified by the reduc stresses give acceptable results for use in radome tion in thermal stress. thermal design. a scientist and his hobby the TECHNOLOGY of WINE-MAKING G. H. Mowbray Wine has been called many things was "the mirror of the heart"; to Others have expressed their feelings since the first known reference to it Shakespeare, "a good familiar crea less kindly, if no less poetically. Mil in Middle Eastern writings dating ture"; and to William Gilbert, "a ton spoke of "the sweet poison of from 2100 B. C. To Aeschylus it panacea for ev'ry conceivable ill." misused wine"; Pope, of "inflaming wine, pernicious to mankind"; while in Proverbs we are warned that "it biteth like an adder and stingeth like a serpent." No matter which of these positions one espouses-and all of them have merit on occasion -officially, wine is the fermented juice of the grape used as a bever age, or so says the Oxford Diction ary.! Federal description, however, is a little more verbose, defining grape wine as "wine produced by the normal alcoholic fermentation of the juice of sound, ripe grapes (in- G. H. Mowbray, an experimental psycholo gist, is a member of the staff of the Theoretical Problems Group of the Re search Center. Dr. Mowbray is the author of " Some Human Perceptual Limits" in the Digest of Jan.-Feb. 1962. 1 Oxford Universal Dictionary on Historical The author in his vineyard keeps a close watch on the growth and health of highly Principles, 3rd ed. (rev. ), Clarendon Press, prized imported vines. London, 1955. 18 APL Technical Digest eluding restored or unrestored pure condensed grape must), with or without the addition, after fermen tation, of pure condensed grape must, and with or without added fortifying grape spirits or alcohol, but without other addition or subtrac tion except as may occur in cellar treatment ; Provided, that the prod uct may be ameliorated before, dur ing or after fermentation, by either of the following methods . ..."2 For practical purposes there are .. only three basic types of wine. They can be denoted briefly as fortified wine, sparkling wine, and natural WIne. Fortified wines are natural wines to which has been added the dis tilled spirit of the grape, i.e. brandy. Sampling red wine to determine its sugar content, G. H. Mowbray is seen here in the cool cellar area where fermentation takes place. They may be either sweet or dry ; thus, they may have a sweetness beverages that need not concern us has an alcoholic content that does (artificially derived ) that may be here. The production of true cham not exceed about 13 %, and it may detectable to the palate, or they may pagne is a tedious and time-consum be red, white, or rose. It is not very be lacking in sweetness-some say ing process that results in a unique intoxicating except in larger quanti "tart," although this is by no means drink that is almost universally ties than most people are willing to an exact description. The fonner appreciated. Its effervescence is pro consume. When drunk with a meal are the ports, sherries, muscatels, duced by a carefully controlled sec it adds a touch of festivity as noth and madeiras. Basically, they are ondary bottle fermentation that de ing else can do. In fact, an ordinary naturally fermented wines that have mands constant care and handling. meal consumed with wine becomes been fortified with brandy, with or The resulting product is a wine of something extraordinary. The old without the addition of sugar prod about 14% alcohol that has no saying that a meal without wine is ucts. They are known generally as equal in terms of finesse, finish, and like a day without sun has much to dessert or aperitif wines. The sweet palatability. The desirability of these recommend it. Today, there is no ones (port, madeira, muscatel, etc.) wines is recognized by connoisseurs excuse for the fonner although the are usually served after dinner with as well as by Internal Revenue Bu latter cannot be guaranteed under fruit or biscuits and cheeses, while reau agents who tax them exorbi any circumstances, even in Cali the drier ones, most often sherry, tantly. fornia. are served as appetizers before din Natural wines are the wines that Since the basic process involved ner. The dessert wines usually have are prod uced by the complete fer in the production of any wine begins an alcoholic content of 18 % to mentation of expressed grape juice. with a natural wine, that is what 25 % and are nearly always sweet That is to say, all of the sugars in will be described here. It is basically to-very-sweet. The sherries have a the juice of the grape are converted a simple one as practiced by our similar alcohol potential but gener to alcohol and carbon dioxide so ancestors, but in the name of stand ally are described as "dry." This is that the resulting wine can be de ardization it has become something not to deny the existence of sweet scribed as "dry." These are the table less than simple. sherries, for there are some, but wines of the world, with an alco A Little Chemistry they are in the minority. holic content varying between 9% In 1810, Gay-Lussac, the French Sparkling wines are epitomized by and 13 % for the most part. Oc chemist, first described the reaction the champagnes, although there are casionally, but only very occasionally, that occurs when freshly pressed a great many inferior wines that are their alcoholic content runs higher grape juice is converted to wine. His made acceptable to some by the ad (to 15 % ), but these are exceptions. analysis revealed the following: dition (naturally or artificially) of Exceptionally also, they contain re carbon dioxide. The latter are sold sidual sugar that has not been con C SH1 20S = 2 C 2H 50H + 2C02. under various names, usually pre verted to alcohol by fermentation, as (grape sugar = ceded by the adjective "sparkling." in the case of sauternes of Bordeau, alcohol + carbon dioxide) There are many federal restrictions barsac of the same region, and the This is the overall expression that on the production of sparkling-wine outstanding wines of the Rhine and says that a quantity of grape sugar the Moselle in Germany, of which, in the presence of the proper yeast 2 U.S. Federal Alcohol Administration, alas, there are all too few. is converted to a certain amount of Regulations No.4 Relating to Labeling and Advertising 0/ Wine, U .S. Government The bulk of the wine consumed alcohol plus some carbon dioxide. Printing Office, Washington, D .C ., 1948. the world over is natural wine. It While Gay-Lussac's formula is gen- 1u1),-August 196-1 19 erally correct, a great deal of an romycetes (the fermentation yeasts ) or "must," as it is technically known, alysis directed toward a more exact give the signal, a wild game of follows. determination of the process has oc musical chairs ensues, creating chaos SUGARS-The primary sugars are cupied wine chemists for the last out of what had been a somewhat dextrose and levulose, which are one hundred or more years. orderly arrangement. When order is usually present in a 1: 1 ratio at ma Careful observation of the above again restored, there is wine, and turity. Since levulose is nearly twice relations indicates that the fermen some products have been created as sweet as dextrose, the significance tation process is thus nothing more that were not in the original solu of this ratio is apparent. Fluctua than a molecular readjustment of tion. tions in the ratio caused by grape the carbon, hydrogen, and oxygen of Temperature is very important to variety, climate, or whatever, must grape sugar. However, there is much the total process because of the in be taken into account by the wine more to it than that. In the first fluence it exercises upon the rate of maker who desires a standard prod place there are two basic types of molecular exchanges and upon the uct. Practically no sucrose (cane grape sugar, namely levulose and solubility of various acids. sugar) is found in grapes of the best wine varieties, but other types dextrose, having the following forms: Theoretically, according to Gay may contain as much as 10 % . Traces Lussac's formula, yields of 51.1 % CH 0H of other sugars and related com 2 alcohol and 48.9 % carbon dioxide pounds such as the pentoses and I should be possible from a quantity CO pectins are usually present. of grape sugar. In actual fact the I alcoholic yield will depend on many CHOH ACIDs-The biological stability of things, among which are the amount LEVULOSE wine is largely the result of its be I of by-products, amount of sugar CHOH ing buffered to a relatively low pH.

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