Bob’s blog from Around Hermitage June 2019
We are fortunate that the Hunter wine industry grew from the enthusiasm of pioneers who were inheritors of the mindset of the age of enlightenment. They formed the Hunter River Vineyard Association in 1847 with a view to exchanging ideas and experience, acknowledging they came from a country devoid of a wine-growing culture.
That is not to say they were not wine drinkers, indeed their knowledge included the great wines of Burgundy, Bordeaux claret and German white wines. Some such as Wyndham and Busby had been on the Grand Tour of France and Italy in the post-Napoleonic era. Wine, of course, was one of the great civilizing influences but no one knew how it was really made.
These men were keen observers of nature and interested in all aspects of viticulture and winemaking. Possibly because of a lack of inherited knowledge they were open to trial and error and the application of the scientific method of experiment and observation. James King of Illawong was probably the best connected with what was happening in Europe. He corresponded with Justus von Liebig the leading scientist of the day and exchanged ideas as well as sending samples to him of wine for analysis.
Liebig is known as the father of the fertilizer industry having discovered the importance of NPK (nitrogen, phosphorus, and potassium ) to plant growth among other things about the time things were getting underway in the Hunter. The invention of nitrogen-based fertilizer and the observation that plants fed on CO2 derived from the air are just two of his major contributions.
Liebig had wide interests and developed a means of extracting beef for long term preservation in the form of “Oxo cubes” and more importantly developed the first commercial infant feeding formula – “Liebig's Soluble food for infants”. This saved many lives as TB was commonly transferred by wet nurses to babies and as such, was a major advance in public health.
Searing of meat to retain juices and flavor is a concept we can be grateful to Liebig for! Drawing on his research on plant nutrition and animal metabolism he argued eating not only meat fibre but also the juices which contained inorganic chemicals was important. The medical journal The Lancet, acclaimed Liebig for revealing the “true principles of cookery”.
Well, wine and food do go together!
It was his interest in the process of fermentation that drew him into the circle of the Hunter River Vineyard Association (HRVA) of which he became an honorary member. Famously he challenged Pasteur over the nature of yeast in fermentation around the 1860s.
Today we know the cells of the yeast Saccharomyces consume sugar in grape juice and transform it into alcohol and CO2 in approximate parts. However, prior to Pasteur, many believed fermentation was a purely chemical process whereby sugar split into alcohol and CO2. It was around 1835 that with the help of
microscopes that fermentation in beer was observed to involve single cell yeast multiplying in vast numbers as the process advanced, that the chemical theory started to falter.
Liebig was among the scientists who observed the process in beer at that time, postulating the yeast consumed the sugar like a small animal and excreted the alcohol from its bowels!
Spoilage of milk and beer were discovered to be due to Bacteria by Pasteur, in again a living process. A biological, not chemical process was involved. Two years later, in 1857, Pasteur presented his “Memoir on Fermentation of Lactic acid” and in 1860 his “Memoir on the fermentation of Alcohol” with carefully researched results showing growth and reproduction of yeast was the cause of fermentation.
Pasteur showed yeast cells on grape skins led to fermentation, juice extracted from inside the grape, uncontaminated, did not ferment.
In nature, without living organisms, without live yeast, no fermentation exists was Pasteur's definitive statement.
James King had been in contact with Von Liebig during this time and was aware of the move to a biological theory of fermentation was in the air. Discussions at the HRVA in 1852 around the topic, caused the Reverend Henry Carmichael, owner of the Porphyry Vineyard, to caution members so as not to bring the association into disrepute by denying the chemical nature of fermentation. The chemical nature of fermentation was along the lines of the Spontaneous Generation theory.
Pasteur put to death the theory of Spontaneous Generation, which from Greek and Roman times until the late nineteenth century espoused among other things, that some life form arose spontaneously from nonliving matter. Mice, for instance, could arise spontaneously from rubbish heaps, fleas could arise from house dust or maggots from dead flesh! When yeast were seen as important to fermentation some adherents to the Spontaneous Generation theory suggested again the yeast arose from the organic matter. It was Pasteur using his microscope that showed in fact the yeast were already growing on the grape skins and contaminated the juice at the start of fermentation.
Pasteur used a series of retort flasks experiments to refute the spontaneous generation theory and to show how microorganisms could contaminate sterile media. He developed the germ theory as well as proving the fallibility of spontaneous generation. He showed microorganisms responsible for contamination of wine, bacteria for gangrene and puerperal fever. It was his work showing how wine heated for 30 minutes at 68 degrees C could be prevented from spoilage that led to the process of Pasteurization.
Liebig, by the time the leading scientist of Europe, challenged Pasteur to explain how the yeast made the conversion of sugar to wine- something Pasteur admitted he could not do. Nothing in science is settled, not even climate.
In 1897 Eduard Buchner accidentally discovered that fermentation could occur in the absence of living cells. He ground up yeast cells and added sugar to preserve the contents for later use. Subsequently, he noted the sugar was fermenting which led him to discover the enzymes in the cells were responsible, for which he was awarded a Nobel Prize in chemistry.
James King had been in contact with Von Liebig during this time and was aware of the move to a biological theory of fermentation was in the air. Discussions at the HRVA in 1852 around the topic, caused the Reverend Henry Carmichael, owner of the Porphyry Vineyard, to caution members so as not to bring the association into disrepute by denying the chemical nature of fermentation. The chemical nature of fermentation was along the lines of the Spontaneous Generation theory.
Coming back to the Hunter Valley in 1847 James King was interested in stuck ferments. King had corresponded with Von Liebig about the issue. King’s solution was to add an actively fermenting wine to the stuck ferment to kick it along. Of course, by then the idea of Levin or yeast being central to fermentation was suspected but not proven.
Another key figure in the development of the Australian wine industry was William Macarthur. On a visit to the Hunter, King had explained his method of dealing with stuck ferments a problem they all faced. King having explained his approach to Macarthur, it became the subject of the inaugural address by Macarthur to the NSW Vineyard Association unfortunately without acknowledgment of King! This led to a temporary falling out between the two, however by the time of the Paris Exhibition of 1855 they came together and both were awarded medals and had their wines served to Napoleon III at the closing dinner.
It was Pasteur who found some yeasts are efficient converters of sugar to alcohol and some not. Some yeasts will stop fermenting as low as six percent alcohol and others continue on up to sixteen or greater levels. He noted even among efficient yeast there are different strains and viticultural regions tend to produce different strains. This leads to a discussion of natural or cultivated yeasts in winemaking, possibly for another day.
Timing is everything they say and here as our wine industry was getting underway one of the longest standing mysteries of civilization- how wine undergoes fermentation was about to be solved. The HRVA, a product of enlightened pioneers is not acting in isolation but rather seeking answers to key questions and despite the distances, through correspondence with one of the key players is in touch. Possibly not having the burden of tradition we were able to respond more flexibly to the changes that ensued.
My sources include the Maitland Mercury and Illustrations from original articles published by Pasteur and available in the Library of Sydney University.
#aroundhermitage#huntervalley#bobsblog
Author: Robert Lusby AM
©Around Hermitage Association