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Amylose and amylopectin

2 October 2012 One Comment

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The chemistry of cooking the perfect pasta – Amylopectin, amylose and protein

A few friends and I are planning a “learn to cook” vacation in Italy next spring. Being competitive by nature and to ensure I don’t appear a complete novice, I have become obsessed with cooking the perfect pasta. From Agnolotti to Zitoni, it feels like I have made and cooked them all.

So, what is my definition of perfect pasta? The perfect pasta should be slightly al dente, not soft or gummy. It will be sticky enough to hold sauce, but not so sticky that it sticks to itself. It set me wondering what the science behind the perfect pasta might be.

It seems that there are three key components to pasta; the sticky part of starch, the not so sticky part of starch, and protein, each having its role.

The chemistry of pasta:

The sticky starch (amylopectin) is a highly branched, soluble polysaccharide. If your cooked tagliatelle sticks together, ending up looking like a ball of yarn, amylopectin is the starch doing the sticking.

The not so sticky starch (amylose) is a starch molecule that becomes gelatinized at temperatures above 65 degrees Celsius. It’s tightly packed, not as branched a molecule, compared to amylopectin.  It is insoluble in water and acts as an emulsifier, blocking tiny fat molecules, helping even the oiliest of sauces bind to the pasta.

The protein mainly comes from egg, a little from the flour, but protein is an important part in pasta making. As it cooks, it forms a sort of string bag that holds the starch granules in place. To accomplish this, the goal is to form a net around both types of starch before the “not so sticky” starch gels, and floats away from your pasta. 

It is important to note, that starches from various sources contain different amounts of amylose and amylopectin, which influence physicochemical properties such as gelatinization, water absorption and paste viscosity. In cooking terms, the amylose/amylopectin (Am/Ap) ratio in the starch affects the pasta sticking to itself and also how the sauce coats the pasta. Be sure to buy the right starch for the job.

So perhaps a key addition to every serious pasta maker’s kitchen alongside the pasta maker, drainer, etc., would be something to measure the Am/Ap ratio of your starch.  Does anyone have any ideas?