Enzymes are bio-chemicals that catalyse reactions. Without them, life as we know it would not exist, or in some instances just be very, very, slow.
Wine is technically the enzymatic transformation of grape juice. In wine making enzymes are important processing tools originating in the grape, yeast and a plethora of other microbes. It is the winemaker’s ability to predict and control the outcome of thousands of enzymatic reactions that produces a quality wine.
In this brief snippet of the wine-enzyme world, the addition of commercially formulated enzymes will be reviewed, whilst avoiding as much jargon as possible.
Commercial enzymes were first used in winemaking during the 1970’s following steps made by fruit juice manufacturers to utilise pectinases for improved clarification and yield.
Commercial enzymes have been developed from a range of fungi genera including Aspergillus, Rhizopusand Trichoderma. The OIV (International Organisation of Vine & Wine) governs the methods of commercial enzyme production in the E.U. At the moment only Aspergillusniger and some Trichodermaspecies have been allowed as source organisms.
Enzymes are naturally occurring and in commercial winemaking formulations are added to help speed up their processes. The most commonly recognised enzyme group are the pectinases, the group that is used the most in wine making. Those who make jam will know that it is pectin that causes the preserve to set. Pectinases break down the pectin chains in the early processing stages. The last thing we want is thousands of litres of wine-grape jelly!
The main enzymatic activity in commercial enzyme preparations is the breakdown of pectin, hemicellulose, cellulose and glycosides. Most commercial formulations will contain enzymes derived from the pectinase family.
Enzyme formulations are designed to have different functions. Some are responsible for aroma release and others are used for colour extraction, clarification, sedimentation and pressing. Pectinases help to breakdown the cellular structures in grapes to release colour, flavour and aroma precursor compounds.
‘Natural’ or minimal intervention winemaking may omit the use of commercial enzymes and the endogenous enzymes present in the grapes slowly facilitate these processes. Avoiding the addition of commercial enzymes results in longer periods of time being needed in order for the lower concentration of endogenous enzymes to achieve a desired result. For example, juice settling may be reduced to 24 hrs using commercial formulations. This process could take several days, or in some cases be incomplete if endogenous enzymes are relied on solely.
Due to the low pH environment of the grape must and possible sulphur dioxide additions, it is difficult for endogenous enzymes to function to their full potential, and their beneficial action is limited. Enzyme formulations are used to alleviate this limiting factor by simply increasing the enzyme concentration.
There are no specific ‘wine enzymes’. Enzymes are classified into 6 different groups (oxidoreductases, transferases, hydrolases, lysases, isomerases and ligases – the pectinases being from the Lysase group). Enzymes are not specific by design; they have distinct functions that can be found in various bio-chemical processes. In enzyme formulations, there may be a number of different enzymes from the group responsible for the breakdown of pectin.
In red wine formulations there will be a higher concentration of pectinase active enzymes that help break down cell structures to release the maximum amount of colour from the skin cells. In a white wine formulation, this active enzyme component will be of a lower ratio.
Enzymes are added at various times during a wine making process, such as at the crushing stages to increase juice extraction, to wine to improve filterability before bottling, or to wine in barrel to speed up lees ageing. Enzyme formulations come in a powdered or liquid format that are simply added and homogenised.
The main advantage of using commercial enzymes is to speed up the winemaking process. This is of particular importance in stages when the juice or wine is vulnerable to spoilage organisms. The winemaker should find the fastest and safest route through these vulnerable states in order to protect the consumer’s health and to deliver a quality wine.
As with any ingredient in a recipe enzyme additions can have negative effects if used incorrectly. When making any addition, the timing, temperature, pH, rate (mass per litre), variety and fruit quality play important roles in the effect it will have. A wine maker relies heavily on the manufacturers’ guidelines and reputation of a product.
Improvements to the purity of the enzymes in commercial formulations have been made over the last 40 years, but as a natural product, there will sometimes be variations in each formulation. Enzymes such as anthocyanase and cinnamyl esterase can cause colour loss and organoleptic spoilage and have been found in some commercial enzyme formulations. Because of this, products are created and developed to minimise or eradicate any negative enzyme impurities and possible side activities.
These cases are rare as the increasing knowledge of the role enzymes in wine making and technological advances in testing and development mean that more control is available to the manufacturer and the wine maker. It is these developments made in wine science that maintain the integrity of the art.
Wines of Momentary Destination
Hornsey, I. (2007) ‘The Chemistry & Biology of Winemaking’ The Royal Society of Chemistry Publishers
Konig, H. et al (2009) ‘Biology of Microorganisms on Grapes, in Must and in Wine’ Springer Publishing.
Moreno-Arribas, V. & Polo, C. (2009) ‘Wine Chemistry & Biochemistry’ Springer Publishing
Reynolds, A.G. (2010) ‘Managing Wine Quality – Vol. 2: Oenology & Wine Quality’ Woodhead Publishing
Ribereau-Gayon, P. et al (2006) ‘Handbook of Enology, Vol. 1 &2’ Wiley Publishers