◆ How did you come to be a winemaker living in New Zealand?Takahiro Koyama -- I lived in Taiwan until I was 15, before returning to Japan to go to high school. I then went to college in the United States for 4 years, during which time I visited wineries in the Napa Valley, which was my first real wine experience. After graduation, I worked in Tokyo which was a bit of a culture shock. So in my late 20s I started thinking 'maybe I should do something outside of Japan, and make something Iike,' and that was the beginning of my interest in winemaking.Getting more serious, I went to wine school at Academie du Vin in Tokyo to study wine basics. This led me to winemaking, and I looked for a university with a viticulture and oenology course. I wanted to make Pinot Noir and Riesling, so my final destination was Lincoln University in New Zealand. I started a 3-year undergraduate course and practical work in 2003 when I was 33.◆ What is the history of your vineyards and the terroir?Mountford was first planted in 1991, with more planted on the hillside in 2000, and then more Alsace varieties in 2004. Then after new owners came along they planted 4 hectares more in 2009. And I have contracts with two vineyards, Williams which was planted in 2000 and Pearson's in 2004. And the Riesling Tussock Terrace vineyard was started in 2005.You can divide Waipara into 2 different soil types. The bottom flat part of Waipara is more gravel soil, which is 95% of the soil in the area, but where we are in Mountford and the Williams vineyard is on an eastern hillside and the soil is clay and limestone underneath which ideal for Pinot Nair and Chardonnay. And I have two other vineyards which are on gravel and limestone, and the wines are so different even within Waipara. This gives me a lot of winemaking options.We always talking about growing degree days as well, and Waipara is in-between Burgundy and Champagne, which is ideal for Pinot Noir, Chardonnay and Riesling and those sorts of varieties, so that is why we have started making sparkling wine as well from 2016, which we are just releasing now. We are making two different types of sparkling wines - one is 100% Riesling Sparkling, and the other is a blend of Pinot Nair and Chardonnay.◆ How long did it take you establish a winemaking style you were happy with?There were two winemakers who really influenced me. The first was CP Lin who was the winemaker at Mountford when I joined. The second was Jim Clendenen at Au Bon Climat in California, where I worked a vintage. They both have a similar winemaking style. Unlike many New Zealand they don't do a long post-fermentation maceration, and that is the kind of wine I like.Over time the biggest change in my winemaking is the timing of when to pick the grapes. In the late 1990s and early 2000s, to make most New Zealand Pinots we waited for the fruit to be really ripe with high alcohol, and that made for a big wine. These days I am looking for a more elegant style and pick about 10 days earlier, aiming for an alcohol level of 13.5 instead of 14.5. For Pinot Nair I use 100% natural yeast. However, for Riesling, I use cultured yeast, because I do very low temperature fermentation.◆ What is the attraction of Riesling?Riesling is my favourite white varietal. As a winemaker it is a dream varietal because you can make sparkling, dry, or slightly sweet through to really sweet wines, depending on the vintage. Riesling was one of the first white wines I drank, and when I tasted a fantastic dry Riesling from Keller it took my appreciation to another level.It inspired me to write an email to Klaus-Peter Keller asking him if I could work a vintage, which he agreed to. Riesling is very elegant - you never blend at Koyama Wines and Mountford Estate it with other varieties, or use oak. It is just the grape itself with this fantastic aroma and acidity. This year we had a lot of rain, but we could still make really good wine even with the botrytis.◆ Tell us about your Sparkling Riesling adventureMaking sparkling wine is very different from other winemaking and a real challenge with a lot to learn. So in 2015, my winemaking friends and I went to Champagne and met with sparkling winemakers to learn how they pick the grapes, press them, and make the wine. I started with sparkling Riesling, and then a Pinot Nair/Chardonnay.While they make a lot of sparkling Riesling in Germany, you don't see it anywhere else. For the sparkling Riesling I made two styles - one is Brut with 8 grams of residual sugar, and the other is Brut Natural with 2 grams of residual sugar, and is completely dry. For sparkling Riesling, the increased acidity is critical. The bubbles are really fine because of the fermentation in the bottle. Usually sparkling wines have a yeasty character, but while this Riesling has some of this, it also shows a Riesling varietal character.Our first sparkling Riesling vintage of just 1500 bottles will be released in June. I want to gradually increase production, but it depends on getting botrytis-free fruit each vintage. The difference with Riesling is that with Pinot and Chardonnay you make the base wine and let it go through malolactic fermentation, but we don't do that for Riesling. I try to age the Pinot and Chardonnay blend in the bottle for at least two years, to get the yeasty, bread, toasty character. However, in Riesling I want to retain varietal character, so it is aged in the bottle for just one year after it is disgorged.◆ What plans do you have in the future for Mountford and Koyama?The biggest project for the last few years was making the sparkling wines. We also took over Mountford, which is a huge project. We have made a significant investment in bringing the vineyards up to par, and will continue to do so. And we have this beautiful hillside vineyard, probably the steepest in Waipara, which is producing wonderful grapes as the vines age. Our goal is to produce outstanding Pinot from these hillside vineyards, as the vine age gets close to 20 years and the fruit expresses the complexity of the terroir even more.Takahiro in center