[The Leaven – exploring the relationship between science and religion (cont)]
In the molecular era, it is now known that fermentation is not only responsible for the leavening of bread but it is also the principle process in brewing and wine making. It ‘s worthwhile taking time to consider how wine was perceived in the biblical era and how its use is viewed in current religious ceremony. Present society now understands that the intoxicating agent of wine is alcohol, a by-product of the yeast fermentation process. It is also understood that unfermented fresh grape juice, or must, is relatively free from alcohol. These principles were not understood by ancient societies, as the knowledge behind the biology of fermentation did not exist. When leaven is used in making bread it is viewed as an impurity and therefore omitted from many sacrificial ceremonies. In contrast wine, which is also produced by a similar fermentation process involving yeast, was not only permitted in sacrifices but was sometimes a principal component.
Wine production occurs naturally in the environment. Grape skins are covered with yeasts and bacteria, mainly members of the yeast family Saccharomyces. When grapes are crushed they ferment, especially in warm climates as yeast fermentation occurs between 20 and 40°C with an optimum growth temperature of around 30°C. The main fermentation is aerobic and takes a few days. It then continues anaerobically at a slower rate for some time. When fermentation is complete the resulting wine is racked from the sediment, a substance containing precipitated organic matter and yeast. In the biblical era wine is produced in animal skins or in jars designed specifically for the fermentation process. In the New Testament the fermentative characteristics of wine were well recognised as is evident in some of the passages. The following parable uses the properties of fermentation to describe how a flexible way of thinking was needed to accept new and fresh ideas:
Nor does anyone pour new wine into used wineskins, for the skins will burst, the wine will pour out, and the skins will be ruined. Instead, new wine is poured into fresh wineskins, and both will keep in good condition
[Matt. 9.17; Mk. 2.22; Lk. 5.37]
Wine is not referred to in the Bible as leaven or unleavened although it does feature in sacrifices and rituals. In the Old Testament it is used in large quantities as part of a daily sacrificial offering that also included animals and unleavened bread [Ex.29.38-46; Num. 28.1-8]. Wine is also offered on the Sabbath and on the first day of the month, where the quantity varies depending on the type of animal used in the sacrifice . Most notably, wine was offered in the daily sacrifice during the festival of the unleavened bread:
The proper wine-offering is two measures of wine with each bull, one and a half measures with the ram, and one measure with each lamb.
It does seem, in respect to sacrifices, that leaven was not associated with wine in the same way as it is associated with bread. Perhaps this is because the process of wine production was not as accessible to the overall population as bread making, therefore it is less likely to be used in domestic ceremonies due to lack of availability. Also as wine is intoxicating and bread is not, perhaps fermentation in bread was simply thought of as a different process. In addition wine is rarely associated with food poisoning although it is possible for some microbial toxins to be found in wine. Generally if wine becomes contaminated during fermentation it is undrinkable and becomes cloudy, perhaps at this stage it might have been viewed as impure and corrupt. Pathogenic microbes usually require an optimal pH similar to that found in animals, this is why ethanol with a high pH is normally used in sterilisation. In fact this could be the reason why alcohol, similarly to salt, is used in these sacrifices, for its ability to sterilise and remove contamination.