All about Food. B:9 Most of the blog will be about my various cooking experiments with some reviews of local restaurants thrown in once in a while. Reviews/food experiences from other place will be included also.

Sunday, November 26, 2006

Gelatin versus Agar-Agar (and math rant)

I wanted to try out a Bavarois recipe that I got from one of my mom's cookbooks. The recipe calls for gelatin, but unfortunately, the only gelatin that's for sale in the local stores is cherry-flavored. I decided to use agar-agar to substitute for gelatin. I started doing research on the net, and I found that almost all the sites said to substitute equal amount by weight of gelatin with agar-agar, even though agar-agar sets firmer than gelatin (therefore ruin the ideal texture of the dish).

I became troubled by people keep calling agar-agar "vegetarian gelatin" because gelatin and agar-agar are NOT exact equivlant. Being a biologist, I always knew that agar-agar is derived from seaweed while gelatin is an animal product, and agar-agar is a kind of poly-saccharide while gelatin is proteins, so two chemically distinctive items. Because of the difference in chemical properties, the physical properies of each item are different also. Agar-agar needs to be boiled before it can dissolve in liquid (just like all those agarose gels/petri dishes I poured back in the lab) and it sets at room temperature. Gelatin, on the other hand, cannot be boiled in liquid and it needs a lower temperature to gel.

In my research for answers to my questions, I found an interesting article about different brands of gelatin can produce different levels of firmness. He contacted the company about the differences in the gelatin, and their answer was a formula that converted one "bloom" (gelling factor of the gelatin) factor to another. The author of the article got angry because he didn't understand it. What's so hard to figure this out? Weight (Bloom 2) = weight (Bloom 1) x square root (Bloom1/Bloom2). I'm not sure why he freaked out about this basic math showing the ratio between the two products. It's not like they wanted him to solve a calculus or even an algebra problem. The article was very interesting and it does show the problem of how to standardize recipes when the intrinsic property of an essential ingredient differs from one to another, but the guy really shouldn't have freaked out about simple math.

This reminds me of something else food and math related that I came across a while back. Someone wanted to make a cheesecake in a 25 cm round pan, but the recipe is for a cake in a 20 cm round pan so the person wanted to know what needs to be changed in the recipe to accommodate the new pan size. Someone replied that the person should increase the amount of ingredients by 25-30%. I really have no idea how that person got that answer because the area of a 25 cm round pan is about 1.5 times greater than a 20 cm round pan so you'll need a 50% or so increase of ingredient. Again, simple geometry math needed to figure this out.



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