Sunday, July 3, 2011

Basic Home Wine Making - Step one: Fermentation

Wine is made by the action of yeast fermenting natural fruit sugars into alcohol. Vitis vinifera - wine grapes are the perfect fruit for making wine as they usually contain enough natural sugars, when ripe, to produce an alcohol level that is strong enough to be stable and inhibit spoilage. No other fruit contains enough natural sugars to produce a stable wine. Natural wild yeasts are found everywhere, especially on the outside skins of of fruit, so by simply crushing grapes and allowing the wild yeast to mix with the juice will produce wine. This is how it all began. Other fruits and juices can be used to make wine at home, but sugar must be added to produce enough alcohol to make a stable wine. A stable wine should contain around 12% alcohol. At this level the antiseptic property of alcohol will inhibit the growth of spoilage organisms and the wine is stable. Below this level wine is very susceptible to mold and bacteria. Alcohol levels much higher than 14% will not only prevent the growth of unwanted bacteria but will inhibit wine yeast as well.

Unfortunately many other organisms, along with the wild yeasts, occur everywhere and some of these organism can spoil wine. Acetobacter is a very common bacteria that will turn good wine into bad vinegar. Modern winemaking does not rely on wild yeast to produce wine. Purified yeast strains have been developed for specific wine making requirements. Other techniques are used to prevent unwanted organisms from contaminating the wine.

Home wine makers can benefit from using purified wine yeasts and by preventing spoilage organisms from reaching the wine. Keeping all equipment and containers clean and sanitary is the most important rule for making good wine. Using a closed fermentation system is another technique for making good wine at home. Closed fermentation simply means using a sealed container that blocks both air and any unwanted bad things from contaminating the wine. During the fermentation process yeast converts sugars into alcohol and carbon dioxide gas. It is necessary to have some way to vent off this excess CO2 gas otherwise pressure can build up inside a sealed container and it will overflow making a big mess and  may even rupture the container. This is easily avoided by the use of a one-way valve or airlock. These are commonly available at any wine-making supply shop or on the Internet. They work by allowing the excess gas to "bubble" out through a one-way liquid trap while blocking air from entering your closed fermentation container.

White grape wines are typically made by fermenting grape juice that is pressed and strained from crushed grapes while red grape wines are made by fermenting crushed red grape pulp for several days before pressing out the juice. This is done to extract the red pigments which are contained in the grape skins. Home winemakers can use many different fruits and juices for making wine. Home grown berry wines are usually made in the same manner as red grape wine and the wine starts with crushed fruit pulp and after several days of fermentation the pulp is strained off and the juice pressed out. Either way the first fermentation period is called primary fermentation and will be very active - foaming and churning away inside the container. In a week to ten days this active period will slow down considerably as most of the sugars are consumed and converted into alcohol.

A large glass jug makes an excellent closed fermentation system to make wine from fruit juice but a bucket is needed when working with crushed fruit pulp. Just remember not to fill your container too full. Four to six inches of air space is needed to be safe - otherwise the excess foam that is produced during the primary fermentation can overflow your container and will make a big mess. You can attach a large plastic tube called a blow-off hose to a jug as illustrated below to create a giant airlock. This is my method when working with juice.

After the active fermentation slows down you should siphon the new wine to another container to finish fermentation and to settle out the yeast. Be careful when you siphon the wine to leave behind as much of the sludge as you can. You can watch it clearing through a glass jug and it will be ready to bottle when it is clear. You want to keep the second jugs filled almost to the top. You can add a little water or some finished wine to top up the jug. Always use an airlock to keep air and bad stuff from getting into your wine. I usually start out making 6 gallons so I have a little extra to keep my 5 gallon jugs topped up.

For making a small batch you can find smaller 3 gallon glass jugs at winemaking suppliers. Start with the 3 gallon glass jug and mix up 2 gallons of juice leaving extra space in the jug - after the primary fermentation period, siphon the new wine into a couple 1 gallon jugs to finish. If you are lucky you can find a 6.5 or 7 gallon glass jug at a winemaking shop or on the internet. These are perfect for larger batches and have enough extra space for starting out with 6 gallons of juice and then siphon it into a 5 gallon glass jug to finish clearing. 

Serious home winemakers will have many different sized containers, both glass jugs and plastic buckets, for making wines.

Wednesday, March 2, 2011

Great Wine-making Resource Website

There is a great website with a set of calculators that can make the chemistry involved in making wine much easier for the average home wine-maker. The site is called VinoEnology and includes a separate page with a very useful set of  calculators for determining additions and dilution rates for sugar-water, acid blend, and sulfites among others.

Correct Acid or pH levels along with the proper use of sulfite is a critical aspect in producing consistently good wine and preventing spoilage. Chaptalization is the process of adding sugar to must or juice before fermentation. This is very important for fruit and berry wine-makers as these ingredients, although very high in flavor, are usually too low in sugar and the volume of juice required to produce a palatable wine-like fermented beverage. Dilution calculation is also necessary when using grape juice concentrates for the home wine-maker.

This calculator is very easy to use with complete instructions. Testing for acid level is a necessary step to determine the amount needed. Most hobby wine-makers learn to do very simple acid titration analysis with kits available at any good hobby wine-making supplier. A laboratory grade pH meter is another method but these are quite expensive and require accurate calibration.

All other calculators on this site are just as easy to use and can be very helpful. In addition all of these calculators are available as an App for your iPhone or Android.

Wednesday, February 23, 2011

Wine-making: Art and chemistry combined.

I enjoy creating and sharing food and wine among friends, but that doesn't explain it completely. I am fascinated with the process of combining ingredients and watching the magic of nature and chemistry transform this mixture into something more then the sum of it's parts. Enjoying the results of my labor is just a happy reward along with the learning experience associated with my failures. As I was surfing the web I found a blog that put into words my very feelings much better that I could have.

Winemaking – Flow of Chemistry and Art  Posted on a blog titled: "Philosophically Disturbed"

Learning about food and wine and meeting like-minded people...

Sunday, February 20, 2011

Rhu de Barb le blanc

Alaska Rhubarb Wine:

Ingredients for 5 Gals. finished rhubarb wine.

15 lbs fresh picked Alaska Rhubarb
15 lbs sugar
3/4 teaspoon Sodium Metabisulfite OR 6 Campden tablets crushed
1 1/2 teaspoon Grape Tannin
2 pkgs Red Star Pasteur Champagne Yeast - in 1/2 Gal. white grape juice starter.

Starting Specific Gravity = 1.105  (approx. 26 degrees brix)

All of my wine-making equipment and containers are cleaned and rinsed with a dilute bleach solution and rinsed again just before use with a Sodium Metabisulfite solution. This includes fermenters, carboys, utensils, siphon hose, fruit press, air locks, stoppers, etc. Keeping everything clean is the number one secret to making good wine.

Yeast starter was prepared with 1 can Alexander's Sun Country white grape concentrate and 3 cans water. Yeast was pitched and kept under airlock for 3 days.

Rhubarb stalks were washed and chopped into 1" pieces and added to a 10 Gal. plastic primary fermenter along with 15 lbs of sugar. This was covered and allowed to sit 24 hours to help extract the juice from chopped rhubarb. The next day I added 4.5 Gal. of water to bring the total volume up to 6 Gals. including sugar and chopped rhubarb. Acid content analysis by titration test was not done to the fresh must as rhubarb is a very acidic ingredient and adding supplemental acid for flavor balancing is not necessary.

Sodium Metabisulfite and Grape Tannin powder were mixed into the must and the yeast starter was pitched. The primary fermenter was covered with a plastic sheet. Primary fermentation continued with daily stirring of the must. After 7 days the rhubarb pulp was removed and pressed and the new wine was transfered to a glass carboy and topped with additional water to 6 Gals. Specific Gravity after primary fermentation was 1.046

The glass carboy containing the new wine was stored in a cool dark location and allowed to clear and was racked again after 3 months. When clear and stable the wine was bottled into standard wine bottles and corked.