Why specify IDY? If, as I was told on the live chat, there's no difference between ADY and IDY (which has not been my experience by a long shot), why not just say "any dry yeast"? There's a huge difference even between yeasts labeled the same - I had an ADY that I was using up to a couple weeks ago, which was performing poorly (grocery store label). When I replaced it with Red Star ADY, the Red Star (from Costco in the 2 lb vacuum sealed bag) was noticeably smaller, dissolved more quickly, and performed much better in the 2nd and 3rd rises than the grocery store ADY. There was a very slight difference in the proofing, but both passed a proofing test. Nevertheless they did not perform at all the same - and this was with yeast that is at least nominally "the same" type. Though I've not bothered with anything but ADY for about 20 years now, I can't imagine that IDY performs exactly the same as ADY when I can see such a noticeable difference in different brands of ADY. I'm confused - help me out here? Here's something I wrote recently for future publication on our site- "What’s the difference between active dry yeast (ADY) and instant yeast? "In days gone by there was a significant difference between active dry yeast and instant yeast. Today, the difference is minimal, and the two can be used interchangeably – with slightly different results. Let’s look at ADY first. "Active dry yeast: The classic ADY manufacturing process dried live yeast cells quickly, at a high temperature. The result? Only about 30% of the cells survived. Dead cells “cocooned” around the live ones, making it necessary to “proof” the yeast – dissolve it in warm water – before using. "These days, ADY is manufactured using a much gentler process, resulting in many more live cells. Thus, it’s no longer necessary to dissolve ADY in warm water before using – feel free to mix it with the dry ingredients, just as you do instant yeast. "ADY, compared to instant yeast, is considered more “moderate.” It gets going more slowly, but eventually catches up to instant – think of the tortoise and the hare. Many bread-bakers appreciate the longer rise times ADY encourages; it’s during fermentation of its dough that bread develops flavor. "Instant yeast is manufactured to a smaller granule size than ADY. Thus, with more surface area exposed to the liquid in a recipe, it dissolves more quickly, and gets going faster than ADY. While you can proof it if you like, it’s not necessary; like ADY, simply mixing it into your bread dough along with the rest of the dry ingredients works just fine. "One caveat: in dough that’s high in sugar (generally, more than ¼ cup sugar per 3 cups of flour), the sugar evens things out, and instant yeast and ADY will perform the same." All of that said, ADY is often purchased in packets, from the grocery store, where oftentimes it's been mishandled. Despite its "good" expiration date, it may well have sat in a viciously hot warehouse for weeks, which will deteriorate any yeast quickly. Even if it's in a jar from the grocery, there's no telling what it's been through to get there. On the other hand, our experience is that the vacuum-packed bricks of instant yeast are sold at places where the turnover is faster; they also might not be subjected to the same conditions as supermarkets. For instance, our SAF Instant is shipped direct from the manufacturer, no stops along the way; and it goes immediately into cold storage, until we sell it. Bottom line: While they might come close to performing the same, given enough rising time, IDY has a better chance of being fresh than ADY. And that makes a huge difference. Hope this helps- PJH

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