When it comes to pitching yeast, it is generally recommended to avoid temperatures as high as 90 degrees Fahrenheit. Yeast is a living organism, and like most living things, it has an optimal temperature range in which it thrives. While yeast can tolerate higher temperatures to some extent, pitching yeast at 90 degrees can potentially lead to stress and even death of the yeast cells.
Pitching yeast at too high temperatures can result in a variety of negative effects on your beer or wine. One of the main concerns is the production of off-flavors. When yeast is stressed due to high temperatures, it can produce compounds that can give your beverage an undesirable taste. These off-flavors can range from esters, which can contribute to fruity or solvent-like aromas, to phenols, which can give your drink a medicinal or band-aid-like taste.
Moreover, high temperatures can also lead to a rapid and vigorous fermentation process, which might not be ideal for your beer or wine. A fast fermentation can sometimes result in incomplete attenuation, meaning the yeast may not fully consume all the sugars, leaving your beverage sweeter than intended. Additionally, a rapid fermentation can also lead to the production of fusel alcohols, which can contribute to a harsh and hot alcohol taste.
In my personal experience, I have found that pitching yeast at temperatures closer to the lower end of the recommended range (around 70-80 degrees Fahrenheit) yields better results. This allows the yeast to ferment at a more controlled and optimal pace, resulting in a cleaner and more balanced final product.
If you find yourself in a situation where your beer or wine must be pitched at a higher temperature, there are some steps you can take to mitigate the potential negative effects. One option is to employ a yeast strain that is known to be more heat-tolerant. Some yeast strains, such as Belgian saison yeasts, can handle higher temperatures without producing excessive off-flavors. However, it is still important to stay within a reasonable range and avoid extreme temperatures.
Another technique you can use is to gradually lower the temperature of the yeast-water mixture before pitching it into your beverage. This can be achieved by adding small amounts of cooler water to the yeast suspension over a period of time, allowing the yeast to acclimate to the lower temperature gradually. This method can help reduce the shock to the yeast cells and minimize the potential negative impact on your fermentation.
While it is generally not recommended to pitch yeast at 90 degrees Fahrenheit, it is crucial to stay within the optimal temperature range for yeast health and fermentation success. By keeping the temperature closer to the recommended range and employing appropriate techniques, you can ensure a smoother fermentation process and a better-tasting final product.