I purchased a new package of yeast. It's a about a 2x2x3 inch vacuum packed brick of granulated yeast for baking. I've purchased and used it twice before without a problem. It's always had normal taste and smell in the finished bread or rolls. This time the rising rolls had a strange odor and similar taste. The process takes 15 minute kneading, 1 hour rise, 1 hour roll rise, 14 min bake. The only Variables are the dry regular rise yeast and the 1/2 cup of whole milk. The granulated yeast is stored in airtight jars in refrigerator. The milk had a very small amount of cream on top. Rise and bake was perfect. Why the smell and taste problem? The yeast is a product of Mexico.

  • 2
    Are you saying you have baked using this package of yeast twice already, or that you've used this brand twice before and this time with a new package something doesn't seem right?
    – GdD
    Commented May 3, 2023 at 13:53
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    Is it normal for your milk to have cream on top? Is it a non-homogenized brand?
    – MJ713
    Commented May 4, 2023 at 2:38

2 Answers 2


You could try testing the yeast in isolation by blooming or proofing it.

Take half a cup of warm, not hot, water (about 100°F), dissolve a teaspoon of sugar in it, sprinkle in a good spoonful of yeast, stir, and then wait for it to bubble. Should take about ten minutes. If you get the weird smell again, you've found the problem; if you get a normal yeasty smell, the problem was probably a different ingredient. (If it doesn't bubble at all, either your yeast died of old age or you made the water too cold or hot.)


I highly doubt that the yeast is the source of your problem here, if you used it twice before without issues it's probably still fine. Most likely the smell has been caused by bacterial growth from another source, likely the milk, which is a good medium for bacteria. If your milk was close to going off it may have already had some off flavors in it, and if it was already starting to have significant bacterial growth that would have accelerated when it was rising/proofing.

I would suggest using fresh milk, or heating the milk to 72°C/165°F to kill the bacteria before using it. You'll need to cool it down before you use it, so plan accordingly.

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    I don't think it's the milk. I have relatives who don't know about official food safety, and for them, baking is a way to make use of milk that has gone off. When used this way, the off-tastes of the spoiled milk are not noticeable. The only thing that does become noticeable is when they use homemade yogurt that has gone off, because it overferments and the acetic acid becomes overpowering - but that never happens with milk. Also, modern ESL or UHT milk is even less of a suspect, because when they spoil, the taste change is almost imperceptible.
    – rumtscho
    Commented May 3, 2023 at 10:04
  • If someone is used to those types of flavors in their baking then it won't be 'off' to them @rumtscho , but for someone who is used to bread tasting a certain way spoiled milk will taste wrong.
    – GdD
    Commented May 3, 2023 at 10:13
  • I wouldn't say that I'm used to this type of flavor, because I rarely eat at my relatives', and I never put spoiled milk in my own baked goods, and neither did my mother when I was growing up. For me, the difference in taste is not noticeable, I only know it because my relatives tell me about it, or when I'm present when they bake.
    – rumtscho
    Commented May 3, 2023 at 10:17
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    I understood the OP's statement "I purchased and used it twice before" to mean that he had purchased and used the same product on two previous occasions, and this was the third time that he purchased it. That is, he's not baked three times with the current batch of yeast, but rather had success with two previous batches and this third batch is not behaving the same. But possibly this is a misreading. Commented May 3, 2023 at 13:51

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