Here are four best ways to test the quality and viability of instant yeast:

1. 1.Observe fermentation activity:

2. Dissolve instant yeast in warm water, add appropriate amount of sugar and flour, stir evenly and place in a warm environment. Watch to see if the yeast begins to ferment and form bubbles. If the yeast is active, the dough will rise quickly.

    

   2.Water activation test:

3. Add a small portion of instant yeast to warm water and add a small amount of sugar. Stir well and let it sit for a few minutes. If the yeast is active, foam will appear in the water and the volume will increase.

    

   3.Fermentation time test:

4. Use instant yeast to make a standard dough and let it ferment in a warm environment. Record the time required for fermentation. If the yeast activity is good, the dough will rise quickly and in a short time.

    

   4.Yeast proofing test:

5. Make a standard dough using instant yeast and a proportion of flour, sugar and water. Divide the dough into two parts, one with instant yeast and the other without. After fermenting for a period of time, compare the volume growth of the two doughs. If the dough added with instant yeast rises more, it means the yeast activity is higher.

    

   Through the testing of the above four methods, the quality and vitality of instant yeast can be initially evaluated. Please note that before testing, make sure the yeast is stored in good conditions and avoid being expired or damp.

Other related:

1.Bread Improver Substitutes | What Methods Can I Use ?

2.Instant Dry Yeast vs Active Dry Yeast: What’s the Difference?

3.Brewer’s Yeast for Dogs:Benefits and Risks - Hz-Focus

4.Role of Yeast in Beer, Wine, and Bread Production

5.What are the types of yeast, don't use the wrong yeast

6.How to Activate Instant Dry Yeast?

7.How Much Yeast In A Packet? 

8.The Best 6 Methods for Storing Yeast