Making Wine: Grape Harvest

 There are many readers writing to us every month and asking for advices and suggestions about problems concerning the production of wine, a sign the “self” production of the nectar of Bacchus is still an activity done by many wine lovers. Besides appreciating it in glasses, it seems our readers also own a vineyard in which, with the same passion, cultivate vines in order to make wine. The many letters we receive about enology - and we are aware of the fact we cannot answer to all of them, either through the pages of DiWineTaste or personally - convinced us to publish a series of articles expressly dedicated to wine making. Of course we do not have pretensions to transforming our readers in expert wine makers: our goal is more humble, we simply want to provide our readers useful information about home wine making, even better, useful information about home production of a wine with the least possible number of faults.

	The grapes are ready for harvesting

 Before beginning the adventure of home wine making, it is time to write a premise about some concepts which will be part of our articles about enology, being aware of the fact what we are about to write could disappoint some readers as well as not being agreed by many. In our articles we will also talk about chemistry and about its use in wine making, as the connection between the two is so tight - as well as useful - that would be stupid to neglect or deny the use of chemistry in the production of wine. After all, wine is undeniably the result of a series of chemical phenomena, including fermentation, therefore, even in case it will not be used any chemistry at all, wine will do that on its own. We should also say the use of chemistry is agreeable only in case it is used in an indispensable way for the production of a genuine and sound wine, while limiting as much as possible faults and playing an indispensable role in the prevention and prophylaxes. It is absolutely deprecable - and not agreed at all - when chemistry is used in order to adulterate wine, even worse when it is cause of disorders for the body. Chemistry is certainly useful, but it is not a game: it is always and appropriate to use it in the strictly necessary measure.

 It was probably happen to anyone to taste a home made wine together with the words of the producer who, proudly, emphasized the fact his or her wine was absolutely genuine and to which «nothing was added», as this would be enough to make an excellent nectar. Although we understand the proud and pleasure in offering a home made wine, produced with passion and conviction, it usually happens that in the glass one sometimes find a wine which is to the limit of being drinkable, sometimes disgusting as well, with evident and serious faults a better prevention and care could have helped to avoid. The most probable cause is that to the wine nothing was added and nothing was done in order to prevent and avoid faults. What we want our readers understand is that a wine is made - first of all - by having a good prime matter: grape. To make a good wine, grape, and therefore its juice, must be ruined the least possible, while preventing the unavoidable negative chemical reactions which take place - naturally or in presence of specific factors - from crushing to bottling. Chemistry, of course used in the right way in enology, must exclusively be used for this: to ensure the integrity of the must and wine, while preventing as much as possible the development of faults and defects, therefore ensuring a better and fundamental hygiene, an indispensable factor for quality.

 Like we said, in order to make a good wine, it is indispensable to have, first of all, quality grapes. When quality grapes are available, the only preoccupation is to process them properly, limiting as much as possible to worsen its quality. This unpleasing inconvenience inevitably happens when the appropriate measures of prevention and prophylaxes are not used. Once again, it is good to remember wine is the result of a series of complex chemical processes, positive and negative ones for quality, and it is therefore appropriate to limit and prevent the negative ones while favoring the positive ones. If it is true a quality grape can only be ruined, the opposite it is not true: a bad quality grape cannot be improved and you cannot expect to make a good wine from it. The old saying “wines is made first of all in the vineyard” represents an indisputable truth. Moreover, having quality grapes - sound, with no faults or molds - not only means obtaining a better wine, but also making a limited use of chemistry.

 The determination of the harvesting period fundamentally depends on two main factors: the integrity of grapes and in particular the presence of mold; the type of wine to be made. The moment of harvesting is usually determined when the grape is considered to be sufficiently ripe or when it reaches its highest level of ripeness expressed by its content in sugar. This condition can be achieved only in case the grapes are perfectly sound: in case of the presence of mold in berries, its development compromises the quality and health of grape, forcing to advance the date of harvesting. The control of grape ripeness is more complex, as it is necessary to do analyses about the quantity of the main components in relation to the type of wine to be made. The typical condition for home wine making does not require, generally speaking, the availability of special equipments in order to do accurate analyses on the grapes - and in particular on acidity - before proceeding with harvesting. The type of analysis done in these cases - also representing a fundamental examination - is about the quantity of sugar, a measure considered to be enough at the time of harvesting for home wine making.

 At the time of harvesting, it is important the grape has the best balance among its essential components and represented by sugar, acids and coloring substances. During the ripening process, in grapes take place the following phenomena:

• sugar increases
• acid decreases
• coloring substances increase
• aromas increase

 The best balance is not always represented by the condition in which the grape reached the highest level of ripeness, that is by the highest quantity of sugar possible. There are cases in which it is better to keep a higher quantity of acids, such as in case of the production of base wines for sparkling wines, or in case of particular grapes whose wines are more agreeable with an appreciable acidity, such as Sauvignon Blanc. Moreover, it should be remembered acidity offers a good support for the perception of aromas and, last but not the least, represents a fundamental requisite for white wines. By exclusively considering white and red wines, as an example, can be defined the following three generic cases:

• for a dry white wine, with good acidity supporting aromas, it is best to harvest grapes a little earlier than its highest level of ripeness. The analysis of acidity is therefore fundamental in order to determine the period of harvesting
• for a white round wine, with a good alcohol content and color, it is best to harvest the grape at full ripeness, in order to ensure the highest possible quantity of sugar. The analysis of sugar is therefore fundamental in order to determine the period of harvesting
• in general terms, for red wines it is best to harvest the grapes at full ripeness with the highest quantity of sugar possible. In fact, this condition ensures the highest quantity of coloring substances, a lower acidity and a higher quantity of alcohol

 Despite the type of analysis to be done on the grape in order to determine the period of harvesting, it is indispensable to prepare a representative and statistically reliable sample. As the determination is based on the analyses done on samples measured few days apart one from another, it is best to write down the result of every analysis in order to have fundamental elements for a comparison. Grape berries, from which it will be obtained the must to be analyzed, will be picked from one or more rows, from different vines, possibly avoiding the external rows. In order to have a reliable measure, 250ml of grape juice will be enough. Particular care will be paid to the picking of berries from different parts of the plant and with different expositions. Berries are then crushed, preferably with a small press, in order to obtain a juice containing all the main elements in representative and significative quantity. On this regard, it should be remembered a soft crushing will make a juice rich in sugar and poor in acid. The must is then poured in a test tube, or in a small clean glass jar, and it is allowed to rest for some minutes in order to decant and in order to let solid parts to deposit on the bottom. Alternatively, it can be filtered by using some cotton wool.

 The analysis of sugar, besides allowing the determination of the ripeness levels of the grape, also allows the calculation of the probable content of alcohol at the end of alcoholic fermentation. The determination of sugar in a sample of must can be done in two ways, both easily usable in home wine making. The first method consists in using a densimeter, of which the most common one is the Babo densimeter. As the density of a liquid changes according to temperature, it is appropriate to know the reference temperature at which the densimeter was calibrated to. The reference temperature is usually 20° C, therefore the measure of a must at a different temperature from the one of calibration, gives a result that must be properly corrected. In order to get the right measure, it is added or subtracted 0.06 for every degree in excess or in defect from 20° C. The measure is done by filling the densimeter's tube with the sample to be measured, while paying attention to not get any foam, until it is completely filled, therefore it is measured the temperature. It is then introduced the densimeter in order to spill the must in excess while paying attention it does not touch the side of the tube. The result can be read by reading the value from the scale relative to the floating point at the surface.

	A portable refractometer

 The value read on the densimeter refers to the so called “Babo” degree, where each degree corresponds to 10 grams of sugar in 1000 grams of must. In order to calculate the probable quantity of alcohol after the end of alcoholic fermentation, it is enough to subtract 4 from Babo degrees and multiply by 0.85 in case of white wines, 0.80 in case of red wines. It should be remembered this is however an approximate value. The second method for the determination of sugar in the must makes use of a refractometer, which also offers the advantage of a more reliable result than the densimeter as it is not altered by the density of other solid substances found in the must besides sugar. Moreover, refractometer allows a more practical and immediate measure, it requires few drops of the must, however it should be considered, in order to have a reliable measure, they must be taken from a significative sample, as explained above. A portable refractometer, which can be used to measure samples directly in the vineyard, generally gives values in Brix, Babo and Oechsle degrees, thanks to the presence of the relative three scales.

 Refractometers are generally calibrated to the measuring of samples at a temperature of 20° C, however the most modern and common models automatically provide for the proper corrections according to temperature, therefore giving a directly usable value. The measure with a refractometer is done by lifting the transparent shield, then few drops are put over the prism, then the transparent shield is closed while paying attention it adheres perfectly and that must drops are uniformly distributed. In order to get a more accurate measure, it is best to wait about 30 seconds in order to allow the must to reach the same temperature of the refractometer. At this point the refractometer is pointed towards a natural light source and the result is read by directly looking through the eyepiece, properly correcting the view until sharp, just like a telescope. Before and after measuring every sample, it is indispensable to clean both the prism and the transparent shield with distilled water, perfectly drying and wiping it with a cotton cloth.

 The measure of samples will be done every two or three days, carefully writing down the result of each analysis. Despite the measuring method used, the harvest will be done when the value of the last analysis is equal to the ones of the next to last analysis. This condition indicates the full ripeness of grapes, that is the highest quantity of sugar and acid, however remembering that, as the ripening process goes on - therefore getting overripe - acid will decrease in quantity while compromising the overall balance of the must. A good habit is to keep an archive of all measures in order to compare them in the following years: an useful reference about the vineyard over time.

 The rule “a good wine is obtained by a good grape” must be scrupulously followed during the operation of harvesting as well. This means the grape must arrive to the cellar sound and undamaged, while paying attention to not crush the clusters with the subsequent loss of juice from the berries. The harvesting is done by using specific scissors, by cutting clusters at the stem and gently laying them in a small harvesting basket. The basket is then emptied in small cases containing about 15-20 kilograms, in order not to crush the clusters on the bottom because of the weight of the ones over them. During the harvest, it will be paid attention on the quality of clusters, therefore rejecting the ones affected by mold or however damaged or faulty, in order not to spoil the must and therefore the wine. The cases will finally be transported to the cellar where the grape will be subsequently crushed and destemmed, therefore obtaining the must which will become your wine.