Hey Jason, which size of whipping siphon should I get? I'm looking at either the .5 liter or the 1 liter, what do you think is best? Do I need to get the iSi Thermo siphon? I'll normally be cooking for 4-10 people, if that matters.
Hi Dan, that's a great question! Because I just got done writing my book Modernist Cooking Made Easy: The Whipping Siphon so I'm pretty up to speed on siphons and how they're used in different applications and group sizes. Here's what I've found.
When it comes to the type of siphon, there are 3 main ones to look at: insulated thermos-style, heat-resistant, and standard. For all my testing I used the iSi Gourmet Whip and I never missed the thermo function. I always have either a refrigerator or hot water bath (or just a pot with hot water in it) around so I didn't need it to stay insulated.
I also like how I can change the temperature quickly with the Gourmet Whip. For instance, fill a siphon the day before, refrigerate it overnight until 30 minutes before dinner, then put it in a water bath to serve it hot. The Thermo one can't do that as quickly or easily. If you're going to be away from a fridge or water bath then the Thermo function might be more valuable.
I do highly recommend getting a heat-resistant whipping siphon. From pouring in hot liquids to cool or heating up the siphon to serve soups or sauces is something I use a lot.
Siphons come in a few different sizes ¼ liter, ½ liter, 1 liter (½ pint, 1 pint, 1 Quart). When trying to determine what size to buy, the best answer is "It depends".
For my testing, I used both the .5 liter and 1 liter versions and they both were perfect at different times. I typically cooked for 2-4 people, with a few parties of 8-10 or larger. I could manage most dishes with either siphon, but each one had it's strengths.
For accents like froths, sauce-like foams, infused alcohols, and other things served in small portions the ½ liter was more than enough for all sized groups, while the 1 liter could be too big for the smaller groups.
For mousse, aerated soups, carbonated beverages, carbonated fruit, marinated vegetables, and other large portions the 1 liter was the better one for all group sizes since it held more.
I didn't use the smaller siphon, but I rarely found myself wanting something smaller than the ½ liter siphon. If you are planning on doing a lot of small infusions, or other very small servings then this size might be good for you.
So I'd just look at what applications you plan on using it for most of the time and start with the size that matches that. For accents and alcohols go smaller, for full dishes / carbonation go larger. And if you end up buying a second bottle, I'd probably get the other size, then you can get a real good feel for which one you're using more.
I hope that helps some. Whipping siphons are awesome, there's so much you can do with them so enjoy!