For the production of high quality pasta, the choice of raw material is essential.
The type of durum wheat, and the characteristics of the semolina that is obtained, defines the quality of the pasta, in particular affected by the quality and protein content (12-16%) and especially by the gluten, corresponding to 80% of the total protein content; the content of carotenoids and the oxidase of the kernel endosperm (the tissue of the seed that surrounds and provides nourishment to the embryo) affect the typical deep yellow colour and its stability. Good semolina should have some basic characteristics:
- percentage of "ash" (minerals) less than 0.90%;
- adequate quality and quantity (at least 12%) of gluten (protein of the pasta);
- constant granulation, suitable to obtain best hydration during the mixing phase;
- purity, not only in terms of hygiene, but also for waste substances (bran and germ).
Starch and gluten, in fact, are the main components of the pasta, responsible for the transformations that occur during cooking, thereby determining the final result and so the actual quality of the product.
Starch is a carbohydrate constituting the 60-70% of wheat grain. Gluten is a viscous, glue-like, substance (from the Latin gluten = glue), which is generated by the interaction of proteins when the semolina is added to the water and the mixing process begins.
Gluten fills the spaces between the starch granules by forming a grating more or less uniform and regular. During cooking, these substances have the exact opposite behaviour: the starch tends to absorb water, swelling up to break releasing its content; while the two proteins of gluten, instead, coagulate to form a very compact grating that surrounds and holds the starch.
If the pasta is of poor quality tends to lose starch, which dissolves in water. The result is sticky pasta, without "character", and water which, after cooking, is cloudy and white.
In contrast, in high quality pasta gluten, transforming, prevents the starch from absorbing water, protecting the inner substance and then not only the taste of pasta, but also its texture.