Humidity and how it affects roast profiles (Gilbert Murray)

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    Shane Lewis

    I was roasting a few days ago and the humidity was high due to pending rain. My roasts were 5 lb in an 8 lb drum. My time profiles were early. 1c went a good 3 to 4 min early. I tried to stretch the time but 2 c came early also. Net result, a roast spanning from city to Vienna. Using the roast profiles for the 8 lb drum as starting point do you have any advice or ratios on how much to back down heat and increase time during high humidity?

    My results from these roasts were somewhat flat. Now I was roasting for an event and got good response but I knew, and the lady sponsoring the event who tasted a sample previously knew this was not the quality that the drum is capable of. Any advice on how to avoid this type of problem would be greatly appreciated.


    Shane Lewis

    From Larry Monday:
    (Living in Houston Texas Humidity is always a concern. As i dont have as much scientific knowledge as Shane’s answer above I do know that there can always be variations of roasts based on many factors. My concern with the humidity in our area isnt as much as during the roast process but during the storage and cooling of the beans as they are more suceptable to the humidity and water vapor in their storage or cooling stage. If the beans were exposed to excessive humidity or lack thereof prior to roast then this could cause a variation of the roast as a bean that looses some of its moisture might roast quicker or the opposite may occur should it gain moisture by not being stored air tight. Additionally you might check the gas flow valves from your grill. Personally I feel that propane tanks are incosistant in the valve flows. I am sure you have noticed this in the ball valves being easy or more difficult to open and close from tank to tank. This could create a restricted gas flow in one tank and the next one you purchase might flow more free. One cool night not long ago I was roasting several pounds and the first roast came very quickly and I experienced a similar scenario that you explained. Humidity seemed low and air was very cool. My conclusion? I cranked down the heat on the grill and achieved a better result. This also occurred after I had switched to a new propane tank. Sometimes its just best to listen to the roast and toss the timer away.

    Larry in Houston

    Shane Lewis

    Sorry I’m just getting to this question, had a problem with the site sending email. Gil, I’m not aware of any humidity factors that might affect the roast. I’m not saying there aren’t any, as I learn new stuff ever day as do we all. But my logic is as follows: At 400-600F that is so far above the boiling point of 212F of water, that most moisture is is pretty well evaporated rather instantly since it’s already in a gaseous state. All that said, if anyone has any knowledge of how humidity affects roasts then please contribute. I’m curious, now that it’s been two weeks, how your roasts are going. I think the unevenness is more likely other factors. Give me a buzz, let’s chat it through.

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