It has just occurred to me that I’ve never written about winemaking. Perhaps it’s because the impetus to my new found hobby, our daughter’s wedding, was such a distraction from our “normal” routine that I seem to have left lots of balls in the air for a while. Never-the-less, here we are in November and alas, my maiden vintage is all but all consumed.
For my first attempt I chose a simple wine – a Riesling Ice Wine. Ice wine gets its name from the time critical practice of harvesting newly frozen grapes late in the harvest season. The late harvest allows time for natural dehydration of the hanging grapes. The diminishment of water concentrates the sugars and maintains a high acidity. Then a late harvest immediately following the first freeze allows for a crush and juice extraction whereby frozen water crystals are left behind and the resulting juice exhibits an ultra high concentration of flavor and sugars. I started with prepackaged juice pressed from naturally frozen Riesling grapes.
The first order of business in each step of the winemaking process involves the sanitization of equipment and tools. For this I perform a thorough scrubbing with hot water followed by an immersion or shower with sodium (Na) metabisulfite diluted in water. After a quick rinse, everything is generally contaminant free.
For the primary fermentation process I used an 8 gallon (30L) food grade plastic bucket with a breathable lit. I combined about 5 gallons (19L) of juice with about 10 grams of dissolved bentonite. Bentonite is a type of expansive clay commonly used in basement waterproofing, cement, ceramics, adhesives and cat litter. Its ability to absorb relatively large amounts of protein molecules makes it a particularly useful clarification agent in white winemaking. This mixture is then diluted with about 2.5 gallons (9.5L) of water. Then I drew a test sample of the mixture and I took a reading of the specific gravity of the future wine using a hydrometer.
Specific gravity is the relative density of a liquid compared to 60-degree water. My hydrometer is a floating glass tube, bottom weighted to remain vertical. There are markings along the vertical sides that allow for a reading of its floating depth. In this case my unfermented ice wine juice weighed in at a specific gravity of 1.16. This reading would serve as a baseline for monitoring the fermentation process and determination of the potential alcohol content of the finished product. Next I sprinkled about 10 grams of cultured yeast on the juice and closed the lid. Thus began the magic of primary fermentation on day 1 of my first winemaking endeavor.
On day 8 I drew a sample, tested it and found the specific gravity to be 1.074. Something less than 1.080 is considered optimal for this wine. By comparing the initial to current specific gravity and utilizing a conversion formula I determined that my partially fermented “young wine” had yielded an approximate alcohol content of 9.8%. So far so good.
At this point I transferred the partially fermented liquid from my primary fermentation bucket into a freshly sanitized 6.5 gallon (25L) glass jug called a carboy. The term carboy is derived from the Persian word qarabah or “big jug”. I used a long plastic tube to siphon the liquid from the bucket to the carboy and left behind a mess of sludgy looking gunk comprised of the sediment from expended yeasts. The transfer process of drawing of wine from the sediment is called “Racking”. And once racked from bucket to carboy, the wine enters its secondary fermentation stage. This allows for a clean finish to the fermentation process with a diminished probability of contamination from prolonged exposure to wasted yeasts. I placed an airlock into the top of the carboy to prevent the intake of oxygen and airborne contaminants.
On days 19, 20 and 21 I sampled and tested the wine to ensure a stabilized specific gravity. Then the wine was racked into another carboy and I added a few grams of metabisulfite and sorbate. These act together to fight off contaminants such as rogue microbes, fungi, mold and wild yeasts. These additives also produce carbon dioxide (CO2). This unwanted gas was driven off by several minutes of vigorous stirring.
Next I added an isinglass fining agent. Isinglass is a gelatinous product of fish collagen. It serves to remove yeasts and hasten the clarification of wines. I drove off the remaining carbon dioxide (CO2) by another several minutes of vigorous stirring and then I replaced the airlock. Now we wait.
As the days go by you can see the coming of clarity as the suspended solids fall away. The clarification process is quite fascinating.
On day 34 I sampled and tested the wine. It still appeared a bit hazy so I replaced the airlock and waited some more. On day 62 the wine appeared to be totally clarified and brilliantly polished. I took final readings – specific gravity of 1.076. This calculates out to approximately 11.5% alcohol content.
I corked and labeled 30 bottles - a combination of 1.5L, 750ml and 375ml. These aged for 6 months and were then transported from Omaha to Seattle and served along with the other wines at Matt and Jenna’s wedding. This 2009 Riesling Ice Wine was a sweet, thick fruity explosion served extra cold and sipped delicately over desert; or in this case, wedding cake. Mmmm-boy!
Click here for a few more pictures of the process.
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