Microstructural studies of pasta and starch pasta

Abstract

The processing methods for mung bean starch noodles were used to form "starch pasta" from various isolated wheat starches. The objective of this research was to evaluate the changes in the surface and internal structure of pasta and "starch pasta" made from various flours and wheat starch before and after cooking. Cooked "starch pasta" revealed a honeycomb-like internal structure similar to cooked pasta when viewed by scanning electron microscopy (SEM). The honeycomb-like structure of cooked pasta is mainly due to the coagulated protein embedded in the gelatinized starch. Swelling of cooked pasta is mainly due to the hydration and coagulation of protein rather than the gelatinized starch. The diameter of cooked starch pasta does not increase as much as that of cooked pasta. A fibrillar protein network of high cooking quality pasta was enveloped in a gelatinized starch, whereas low cooking quality products contained more diffuse gelatinized starch in a less extensive protein framework. Determination of pasta cooking quality was more dependent on a continuous protein network than the physicochemical properties of the gelatinized starch. In the absence of coagulated protein "starch pasta" strands fractured into small pieces and did not swell. This was in contrast to the pasta made from flour or durum wheat semolina which became swollen after 20 minutes of cooking.