Spit or swallow? There are a few issues surrounding this decision when wine tasting, including whether you experience the wine properly when you spit, the social acceptability of spitting, and the most elegant way of doing it. To an extent the issues overlap a little, but I would like to focus on the amount of alcohol your body absorbs while tasting. Even with this focus, there are number of factors to consider.
Perhaps most importantly there is your ability to get home safely afterwards, critical if you are driving of course. Professionally, it is also important not to have your palate blunted by the effects of alcohol towards the end of the tasting, though this needs to be weighed against the possibility of not properly experiencing the wine if you don’t swallow. Finally, there are longer term health concerns surrounding alcohol consumption. However much we might be tempted to dismiss the latest government advice, there is certainly a limit beyond which alcohol consumption is unhealthy. But I am not going to preach here. I shall merely do my best to examine the evidence for how much alcohol we take on board when tasting wine. However, as you will find out, it doesn’t depend merely on whether you spit or not.
Firstly, I should point out that there is a lot of anecdotal evidence kicking about the Internet on the subject of intoxication and wine tasting, a lot of it contradictory. Some involves the use of consumer-quality breathalyser equipment, which as far as I can establish is very unreliable, but I did also find a reference to judges of an Australian wine competition being breathalysed by the police (presumably in the pursuit of science rather than a convictions) after a hard day’s work tasting and spitting an unspecified number of wines. The judges were found to be comfortably under the Australian drink drive limit. That seems to be at odds with a lot of other anecdotal evidence of tasters not feeling fit to drive after a day of tasting and spitting, and I think the devil is in the detail, e.g. number of wines tasted.
The only hard evidence I have found for swallow vs spit comparisons of blood alcohol concentration is a single study, The Bac(chus) experiment: blood alcohol concentrations after wine tasting, which was published a few years ago in 2012. It used a very specific experimental protocol, but nevertheless provides a good starting point.
The basic idea was to simulate a common wine tasting format, with and without spitting. Firstly with white wines and then with red, the subjects were required to do the following 5 times: rinse part of a 15 ml sample through the mouth for 15 seconds and spit, wait 1 minute, rinse the rest of the sample through the mouth for 15 seconds and spit, wash the mouth with water, wait 5 minutes. Between the white and red wines, there was an additional 5 minutes of waiting. Then, 15 minutes after the last wine, a blood sample was taken for analysis. Two weeks later the experiment was repeated, except this time the subjects swallowed the wine. 10 subjects participated in the first part of the experiment, but it seems 3 of them dropped out for the second part. The authors say the wine strength was 11.5-13.5%, and also give some details about the experimental subjects, but those details do not seem to be too important to the broad conclusions about spitting.
The blood samples were taken when the BAC (blood alcohol concentration) could be expected to be about at its maximum. For the spitting part of the experiment the BACs were in the range 0.01-0.06, which can be compared to the legal limit for driving in the Netherlands (where the research was carried out) of 0.5. The authors assume that these levels of BAC are due to absorption though the inside of the cheek. For the swallowing part of the experiment the range was 0.3-0.63. In other words, if you spat your BAC would be about an order of magnitude less than the drink-drive limit, while if you didn’t you would stand a good chance of losing your licence if caught. Worryingly for a scientific paper, and hardly a great advertisement for Open Access publishing, the authors do not state what unit they use for BAC, but as they are in the Netherlands it would be g/L – grams of alcohol per litre of blood. Note that in England and Wales the drink-drive limit is 80 mg/100mL, or 0.8 in the Dutch system.
So that’s the story for the precise set of conditions used in the experiment, but how may any changes to those circumstances affect the BACs? Let’s start with some factors mentioned by the authors. Firstly, if you have food in your stomach initially, or if you eat when tasting, it will tend to slow down the absorption of ingested alcohol as the alcohol will spend more time in your stomach, where the rate of absorption is less than in the small intestine. Note that the experimental subjects started on an empty stomach, and did not eat anything while tasting. The authors also point out that it takes about an hour for the body to eliminate the alcohol contained in a glass of wine. So an hour spent between finishing the tasting and starting to drive should, at very least, make a big impact on the amounts of alcohol swallowed in this experiment. Also more time spent in the actual tasting would reduce the BACs.
The authors also point out that if you drink more wine then you will get more alcohol in your blood. Pretty obvious really, but I think this is an important practical concern. 15ml is a usable pour, but a lot smaller than I am used to. There is 15ml in the ISO glass shown here, and it is well below the widest part of the glass. Also bear in mind that the rate at which the body can metabolise alcohol is more or less fixed, and it is when the absorption rate exceeds this that BAC increases. That suggests that if you double your alcohol consumption in the same period of time, your maximum BAC will more than double.
I also suspect that the spitting technique, and use of water, is important. I don’t know anyone who rinses their mouth after every wine in a tasting, and if you do not do this then of course wine stays in contact with the cheeks, and alcohol will continue to be absorbed by them, for a much longer period of time. There is also the issue that some residual wine may sneak down you throat when you swallow saliva.
For me personally at least, everything points to the benefits of spitting at tastings, even small tastings of 10 wines or so, and even if not driving. Unless you really enjoy the act of swallowing when tasting, or really believe it is necessary to properly judge the wine, why do it? The benefits have already been mentioned above: accident prevention, health and acuity of flavour perception. I would much rather save my weekly quota of alcohol units for the times when I am really enjoying wine, than use them when tasting. But if you enjoy combining tasting and drinking wine, or ignore government health warnings anyway, I suppose that is a very different situation. As for needing to swallow to properly judge a wine, there are some reasons to believe swallowing gives you a more complete impression of the wine, but I am not convinced it makes vary much difference. Besides, I think there is already enough artifice in conventional wine tasting to render any judgement moot when it comes to real life, whether you swallow or not.
Anyway, must go now to meet some friends and open a few bottles with a meal. Tonight I shall swallow.