By Julia Phillips, Dec 1 2016 08:46PM
Most of us could probably answer that one! For me, it has always been bubbles throughout the glass and a layer of mousse (the foamy bit on top after pouring a glass in case you’re wondering) residing on the top. However, I have been interested in what the ‘perfect glass of Prosecco’ should look like in terms of the bubbles and mousse as there seemed to be variations and I wanted to understand why.
My curiosity started a few years ago at my trade launch when my Prosecco had hardly any bubbles or mousse whilst using my special Riedel (the world’s best) glasses. These were the very same glasses which were full of bubbles and mousse at Riedel UK and my photo shoot a few weeks prior. I later discovered that as fabric softener had been used on the polishing cloths, the softener transfers to the glasses and it had killed all the bubbles. No one told me that one before!
Home testing. New glass on the left (bubbles and mousse). Clean glass on the right (a thin ring of mousse and bubbles forming from the centre).
Riedel advised me it was best to use a dishwasher to wash and dry their glasses, and then polished with a microfiber cloth (which hasn’t touched softener, obviously). I followed these instructions but was still left disappointed with Prosecco bubbles only appearing to form from the centre of the glass and the mousse quickly dissipating. It just wasn’t how they performed when they were new and ‘straight out of the box’.
Still getting frustrated and after further investigation, I discovered that there can be a build up of a non-rinsable residue which causes a film to form on the glass, affecting bubble formation. Ah this must be it I thought! It was suggested I use neat lemon juice to rid the residue, but disappointingly again it made no difference.
Some time later, I learnt about a chemical product that strips the glass of the non-rinsable residue which is used commercially in the pub industry. Surely this will solve my bubble issue?! I bought the product ‘Renovate’ made by Proton, the UK’s leading chemical product manufacturers of glassware cleaning solutions. As the product is intended to be used commercially the product didn’t have instructions for use with a domestic dishwasher so I contacted Proton. I spoke with Damien, Proton’s Research & Development Manager - a complete chemistry and glass cleaning genius! Following Damien’s advice, I set about using my Renovate, new dishwasher settings and new detergent with high expectations. Disaster! It didn’t work. How could it not work!?
Following more conversations with Damien and further testing with Steve at Riedel UK (MD and glass guru), I finally understood the reason for the lack of bubbles/mousse. So here it is:
• My glasses didn’t have a non-rinsable residue on them. They hadn’t been used long enough for that to develop, so the Renovate product didn’t have a job to do.
• When the glasses were first used in Riedel’s showroom (and for my photo shoot), they were new out of the box. After a polish, it is highly likely they would still have cardboard particles, tiny specks from the production process and dust in them. These particles act as nucleation points to give the bubbles something to form from, so a spread of bubbles throughout the glass is to be expected.
• My glasses after washing were in fact ‘too clean’ to allow the glass to be completely filled with bubbles and residing mousse.
• Most sparkling wine glasses are manufactured with a nucleation point etched at the centre of the bottom of the inside of the glass. This point is there to help bubbles to form.
• As Riedel’s glasses are made from high quality crystal glass with virtually no manufacturing imperfections they are completely smooth apart from the intentional nucleation point. This is why the bubbles only appeared from the centre (after the glasses were thoroughly cleaned) and why sometimes on inferior or ‘dirty’ glasses you may see the bubbles dispersed throughout the glass.
Bubbles forming from the nucleation point; the perfect glass of Prosecco.
My early assumption of how a glass of Prosecco should look (or indeed Champagne, Cava or other sparkling wines) (ie, full of bubbles and a layer of mousse) was now changing if the ‘world’s best glasses’ don’t produce that effect. During another visit to Riedel, we tested new ‘out of the box’ Riedel Prosecco Superiore glasses vs the same glasses cleaned in a dishwasher. As a result, I then discovered with the help of Steve, why the Riedel Prosecco Superiore glasses really do give the perfect result after cleaning:
• More mousse was evident on the new glasses vs the cleaned glasses. The mousse soon disappeared on the cleaned glasses. The layer of foamy mousse may add to the visual effect, but it formed a cap and prevented some of the aroma from escaping compared to the more intense aromas given off in the cleaned glass.
• About 80% of our sense of taste comes from aroma - the Prosecco didn’t taste as good in the new glass compared to the cleaned glass.
• The bubbles in the new glass didn’t last as long as the bubbles in the cleaned glass. This is because there are essentially more nucleation points in the new glasses caused by the dust and other particles, therefore releasing more carbon dioxide in the form of bubbles. The bubbles in the clean glass were still fizzing after 1 hour of testing, whereas the bubbles in the new glass had almost gone.
This is in addition to the glass being the perfect shape to accentuate the wonderful characteristics of fine Prosecco Superiore, which are to be appreciated and enjoyed to the very last drop.
The perfect glass of Prosecco (not that you can see the bubbles on the photo – they are there!)
So finally, I had my answer, which had been puzzling me for the last few years. I now know what the ’perfect glass of Prosecco’ should look like. I would much rather sacrifice a few bubbles and mousse for:
• a superior aroma
• a superior taste
• longer lasting bubbles
• a beautifully gleaming (and there’s another story), crystal clear elegant glass
rather than a glass shared with cardboard particles, a layer of dust and who knows what else giving less aroma, lacking on taste and goes flatter quicker (not that Prosecco is in my glass for too long!).
Special thanks to Steve McGraw at Riedel UK and Damien Sleath at Proton, whom without their help, I would still be extremely mystified.