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Book 1, Lesson 4
Fermentation

In the 1939 edition of the International Standard Bible Encyclopedia, the author of the subject, “Wine,” says that it was impossible to keep grape juice from fermenting in ancient Palestine. He thinks the people were not able to preserve fresh juice without modern methods.

Many people today take for granted that all grape juice in Bible times naturally fermented and became intoxicating. Is this true? How is alcoholic wine made? Is it easier to preserve than grape juice?

I. TWO KINDS OF FERMENTATION

Ferment means to boil up or surge up. Bacteria, yeast and mold enzymes cause fermentation.

Two kinds of fermentation are important to wine growers. Vinous fermentation from yeast produces alcohol. Acetous fermentation from bacteria turns the juice sour. If acetic acid bacteria get into any alcoholic drink, they will ferment and turn the alcohol to vinegar.

Vinous Fermentation Produces Alcohol

Alcoholic winemakers want only vinous fermentation. Vinous fermentation requires 4 indispensable conditions:

  1. the right amount of sugar
  2. the right amount of water
  3. the right amount of yeast
  4. a temperature between 40 and 80 degrees.

a) and b) Sugar and Water

If juice has less than 18 percent sugar the wine will be thin and sour and will not keep. An amount of sugar over 26 percent will make the yeast slow down and stop fermentation.1

Winemakers can use an hydrometer to measure the density of the juice. It will tell them how heavy the juice is with sugar. If there is too much sugar, they can add water. If the juice is too light, they add sugar. This must be done very carefully.

c) Yeast

The skins of grapes carry a powdery cover called the “bloom.” This is made up of molds, bacteria and many kinds of wild yeast, including the true wine yeast. After crushing the grapes to break them and to get the juice to flow out, professional alcoholic winemakers often kill all the yeast in the juice. Then they measure and add a pure strain of yeast.

Wild yeast found in the bloom on the grape skins will make alcoholic wine from squeezed grapes if the sugar, water and temperature conditions are right. But vinegar bacteria and molds which are also found in the bloom ruin the wine. Winemakers warn that wild yeast causes “the astringint taste (biting taste) of some wines and the turning to vinegar of others.”2

Yeast is a single cell living microorganism, biologically classified as fungi, that grows on the nutrients in the grape juice. It can live with or without oxygen. With oxygen it reproduces rapidly by budding. Without oxygen, the yeast stops multiplying and the enzymes in the yeast begin to convert sugar into alcohol and carbon dioxide. This second process is called fermentation.

Because of the way yeast works, wine fermentation has two stages: primary and secondary or aerobic and anaerobic fermentations. During the first stage of fermentation, called the primary stage, or the aerobic stage, winemakers put yeast into the juice and control the oxygen because they want to multiply the yeast. The juice is stirred daily. The primary stage may last 4 to 7 days. About 70% of the fermentation activity occurs during these first few days.

Even though the yeast’s energy is focused on reproducing itself during primary fermentation, alcohol is also being produced. As yeast enzymes begin to turn sugar into alcohol and carbon dioxide, clots of white foam show up on the surface of the must (juice). The foam is carbon dioxide bubbles and since they are heavier than air, they form a protective layer on top of the fermenting juice, keeping out the air. The juice will almost look as if it is boiling.3

In the secondary stage of fermentation, or the anaerobic stage, winemakers, who carefully sanitize everything, keep the mix in an air tight fermenter. A device called an airlock allows carbon dioxide to escape without letting oxygen or unwanted organisms in. The remaining 30% of fermentation occurs in the secondary stage at a much slower pace. It may last, continually slowing down, from two to three weeks, depending on the amount of sugar in the fermenting juice.

The hydrometer enables winemakers to gauge both the primary and secondary stages of winemaking. When the alcohol content in the juice rises to a certain point, the alcohol itself kills the yeast. At the end of fermentation the yeast settles to a firm layer on the bottom of the fermenting vat.

d) Temperature

One winemaker says that experiment has shown time and again that yeast cells ferment best at a temperature between 60 degrees and 75 degrees Fahrenheit. This is the temperature range for achieving the best results. Yeast will ferment at 40 degrees and also up to a temperature of 100 degrees over which the cells are killed. They are unhappy and ailing over 80 degrees.4  (Note: a temperature tolerant yeast advertised in 2005 will ferment at higher temperatures; it has special recommendations for handling.)

Another wine expert tells us that yeast does not ferment well below 49 degrees Fahrenheit. He also says that if the fermenting juice is allowed to stay for any length of time above 80 degrees, it may spoil. Since harmful bacteria like high temperatures, they multiply rapidly and soon ruin the wine.5

Fermentation itself raises the temperature of the juice. Professional winemakers check the temperature carefully and if necessary, they cool down the big vats of fermenting liquid.

Acetous Fermentation in Fermented Wine Produces Vinegar

Winemakers call it “spoiling” when certain bacteria turn alcoholic wine into acetic acid or vinegar.6 Acetic fermentation “. . .  is the most dread of all wine diseases to both amateur and professional.”7

The vinegar bacteria can be airborne, but it is also carried by the vinegar fly. These tiny flies are the ones we see around rotten fruit. One writer says they appear “as if by magic if you leave a ferment exposed.”8 Vinegar bacteria are one reason why winemakers keep air from the juice. Air is dangerous to the wine.

If juice is too thin (juice with not enough sugar, or too much water) it will ferment to alcohol first. This is vinous fermentation. But immediately after that, acetous fermentation starts and it turns to vinegar.

All alcoholic wine will turn to vinegar if air gets to it.9

Man Must Control Fermentation to Get His Alcoholic Drink 

Alcoholic winemakers carefully raise the right kind of wine grapes, or buy a special concentrate. They put in the correct yeast. They measure the sugar in the must. They keep the fermenting juice at the right temperature, and protect the juice from air. If man did not take these steps, his alcoholic wine would soon be vinegar. Vinegar exposed to air breaks down to water and a few salts.

Grape juice does not ferment in the grape itself. Only as the juice is squeezed out of the fruit can it ferment. Fermentation is part of the death process of the fruit. Fermentation, putrefaction (smell of rotting) and decay (gradually going bad) are processes of decomposition (breaking up).

II.  FERMENTATION IN HOT COUNTRIES

In Bible lands the summers are dry and extremely hot. From the beginning of June to the beginning of August the heat increases, and the hot season lasts until early October. In 1867, Captain Wilson said the temperature was 110 degrees Fahrenheit after sunset in July at Engedi. The nights were so warm the people slept on the house tops.Warm growing seasons cause fruit to be sweeter because heat produces more sugar.

The grapes of Bible lands were very sweet. Harvest time or vintage in September was still hot. The valleys of Eshcol and Sorek, famous for their grapes, had temperatures in the vintage months of 100 degrees.10

These two facts: a) the very sweet fruit with high sugar content and b) the hot temperature at harvest time, would lead the grape juice to start fermenting  from bacteria. It would turn sour.11

The juice from the palm tree acts just like grape juice. Mandelslo, who lived in 1640, told about getting palm juice out of the top of the palm tree by making a cut in the bark and fastening a pot under it all night. He said it was very sweet wine. He called the juice wine. But, he said, if the juice was collected during the day, it corrupted immediately because of the heat and was good only for vinegar. Palm wine, a traveler said in 850, if drunk fresh is sweet like honey; but if it is kept it turns to vinegar. Palm toddy, Rev. Macleod, D.D., said would be tolerated by the severest teetotaler. There was no alcohol in it.12

The Jewish people near Jericho and Engedi made very sweet palm “wine” called luscious liquor or drink. They boiled the juice to keep it sweet.

Sweet is the natural taste that everyone likes. It is important to know that ancient people in hot climates loved sweet drinks. The Bible says Canaan was a land flowing with milk and honey.

To save the grape harvest from spoiling something had to be done to preserve the juice sweet immediately. One way to save it was to boil it. 

III.  PRESERVING FERMENTED WINE

Ancient wine makers had a very difficult time keeping their juice from spoiling while it was fermenting. Wine makers today can use pasteurization, refrigeration and other inventions to control fermentation.Preserving the wine after fermentation so that it would not spoil was hard for ancient wine makers too. But wine makers today also have to carefully follow through a step by step program of treating the wine after fermentation. Even the way the wine is put into bottles is important. 

As you think about it, does it seem easier to preserve alcoholic wine than to preserve unfermented grape juice? The truth is that it is just as easy and maybe easier to preserve the fresh juice.

Wine May Sour Quickly

Marcos Cato (234 – 150 B.C.), a Roman writer, listed some rules for selling wine in jars. The buyer was given three days to taste the wine after he bought it. If it was sour or musty, the sale didn't go through. Dr. Bacchiocchi says, “The fact that the purchaser was to taste the wine within three days of purchase or take it as it was, shows how quickly wine was subject to turn sour or musty.”13

Ancient Methods of Preserving Wine

Wine makers used boiled down must, resin, marble dust, lime sulphur fumes, crushed iris and salt to preserve their wine. Sometimes the wine had a bad odor that was absorbed by the brims of the wine jars. Cato advised making a cream of boiled must, crushed iris and Campanian melilot and smearing it over the brims of the jars.14

If the wine turned bitter, it could be sweetened by using special recipes. One was to “heat a thick clear piece of roofing tile thoroughly in the fire. When it is hot coat it with pitch, attach a string, lower it gently to the bottom of the jar, and leave the jar sealed for two days.”15

Columella, who lived at the time of the apostles, said the best fermented wine could be kept without a preservative. This wine must have been rare because he too gave much advice on ways to preserve alcoholic wine. He thought salt should be used to prevent a moldy taste. Three chapters of his work, On Agriculture, explain how to use pitch in solid or liquid form as a preservative. He wrote at great length about the use of must. “Let us . . . preserve our wine with boiled down must of a year old, the soundness of which has been already tested.” 16

Boiled down must kept better than the fermented wine. It was boiled down to one half or one third of its volume. Spices and preservatives such as pitch and turpentine resin were added to it.

As we read the ancient writers we can see that preserving wine was no simple matter. “In fact,” writes Dr. Bacchiocchi, “in some places the risk of preserving fermented wine was so great that . . . all the vintage was boiled down and preserved as sweet, unfermented grape juice.”17

Endnotes

  1. Homer Hardwick, Winemaking at Home, Thomas Y. Crowell, New York, 1972, p.52.
  2. Walter S. Taylor and Richard P. Vine, Home Winemaker's Handbook, Harper and Row, New York, 1968, p.38.
  3. Ibid., p.71.
  4. B.C.A.Turner and C.J.J.Berry, The Winemaker's Companion, Simon and Schuster, New York, 1972, p.82.
  5. Hardwick, Winemaking,p.45.
  6. Taylor and Vine, Home Winemaker's, p.22.
  7. Hardwick, Winemaking, p.105.
  8. Turner and Berry, Winemaker's Companion, p.71.
  9. Ralph Auf der Heide, Illustrated Wine Making Book, Doubleday and Co. Inc., Garden City, N.Y., 1973, p.45.
  10. Dr. William Patton, Bible Wines, Sane Press, Oklahoma City, p.22.
  11. Ibid., p.18.
  12. Ibid., pp.18,19.
  13. Dr. Samuele Bacchiocchi, Wine in the Bible, Biblical Perspective, Berrien Springs, Michigan, 1989, p.111.
  14. Ibid., p.112.
  15. Ibid., p.112.
  16. Ibid., p.113.
  17. Ibid., p.114.

 

 

 

 

 

 

 

 

   
 
Copyright 2005
Woman's Christian Temperance Union
of South Dakota