Pasteurization……..HELP!

[kegage]

I will get the devastating part of this out of the way first. Due to, what I believe, is temperature shock I have lost two gallons of sake.

The Set Up: I did most of the secondary fermentation, of a six gallon batch, in a five gallon carboy. I racked that into one gallon and three liter glass wine bottles, and allowed these bottles to sit on the counter overnight to warm to room temperature. The plan was to pasteurize and age the sake in these bottles.

The Procedure: Filled two stock pots about half full with cold tap water and placed on burner with the flame set as low as I could manage it. I then paced the bottle in the pot with the cap off, and inserted the probe of a thermometer with the temperature alarm set at 140F.

The first bottle broke at about the five minute mark. I turned off the heat to both pots and removed the unbroken bottle from its pot. After several minutes of many “gosh darns” and dagnabits”, I believed that the breakage occurred due to the direct contact of the glass bottle with the metal pot. To insulate the glass from the metal I folded two dish towels four times and placed them on the bottom of the remaining pot, placed the second bottle on top of the towels. This raised the bottle about one inch off the bottom of the pot. I then repeated the above heating procedure. The second bottle also broke at about the five minute mark.

Observations:
1)The temperature of the sake was lower than I expected it to be. About 63-65F.

2) The temperature of the water in the pots was still cold to the touch. It had not warmed to any perceivable degree.

3) Both bottles broke in the same time frame, and in exactly the same manner.

Speculations:
1) It is possible that there were micro fissures in the second bottle caused by the same stresses that caused the first bottle to break. However it showed no visible cracks or was leaking.

2)Given that the sake temperature was 63-65F, and the cold tap water temperature was still at its normal temperature (approximately 75F), is it possible the difference in the temperatures between the bottle and the tap water was enough to cause temperature shock?

I would appreciate any advice, experience pointers, or speculation the forum cares to give.
Thanks in advance,

Kevin
P.S. Now I have to make more sake sooner than I had planned. Well shucky darns!

[taylor_madeak]

Gas or electric stove, Kev?

[kegage]

Gas, Bob

[dray]

I hate to ask, but did you cap the bottles first?

[taylor_madeak]

I suspect the gas stove might be the culprit, they put out more heat in a more concentrated space than electric stoves to, resulting in hot spots that can shock your glass. Try putting a trivet or a cast iron pan between your water bath and the flame.

[kegage]

I had the bottles uncapped.

A friend of mine also suggested something like a trivet, but he was speaking of a rack in the pot to elevate the bottle off the bottom of the pan.

I, of course, am a little antsy about trying it again without being pretty sure of success. Don't want to lose any more. I will do a test with a bottle filled with water before I try the real thing.

It was also suggested to use a plactic bottle, like the Arizona Tea bottles, but I am not sure if that could affect the sake.

Another suggestion, from the owner of the brew shop here, was to "bake" the bottles in the oven by slowly bringing the temperature up. He said that is the way beer is pasturerized, but I had not heard of it. Something I just don't know, I guess.

On a slightly different subject: If you remember, I was doing experiments to see if tane-koji could be produced from freeze dried koji. I believe I have figured most of dfficulties out, and have what I believe is going to be a very successful batch underway right now. If you are still interested, I will write that up and send it to you in the near future.

Thanks again,

Kevin

[kegage]

Update: I did the experiment described in my last post, and was successful.

The Basics: Measured the temp of the sake to determe what the temp of the water in the bottle should be. I then monitered the temp of the tap water, adjusting the hot and cold, until the tap water temp matched the sake temp. Did the same for the water in the pot so that the temp of the sake (water) and the water in the pot matched.

Started the pasturization procedure using a cast iron skillet for a trivet as Bob suggested. I also put a small baking cooling rack in the bottom of the pot and placed the bottle on the rack.

Due to the "trivet", even with the burner on high the temp rose extremely slowly.
After two hours and the sake temp only being 85F degrees. I got impatient (rare for me) and decided to see if putting the pot on the heat directly would cause thermal shock. Removed the trivet, reduced the heat to low and put the pot on the burner. The temp increased faster. I decided to chance things and slowly turned the heat up to medium. The desired 140F temp was reached in less than an hour.

I will be trying for real today using the above method. Wish me luck.

[kegage]

Update to the Update: As written yesterday I used the procedure I desribed to attempt to actually pasturize some of my sake. I am please to report it was successful and wroked exactly the same way the experiment did.

Thanks again Bob and company for all of you help and advice.

Kevin

[taylor_madeak]

No problem, Kev, I'm glad you got it sorted out.