Characterizing starch structure in a gluten‐free pasta by using iodine vapor as a tool

Abstract

The suitability of starch–iodine complex to highlight differences in chain mobility and crystallinity of starch in rice pasta was investigated. Two pasta samples were produced starting from the same rice flour (RF) and using a conventional extrusion process without (Process A) and with (Process B) a preliminary extrusion‐cooking step. Based on the absorption/scattering coefficient (K/S) spectra (obtained after equilibration above K2SO4 and exposure to iodine vapor), Pasta A showed a behavior similar to RF. Process B exhibited a greater iodine binding capacity suggesting greater starch chain mobility. Moreover, the extrusion‐cooking conditions seem to favor the loss of starch crystallinity and the formation of larger amorphous regions. The organization of starch polymers observed in Pasta B could account for its higher capacity to water absorption during cooking.

In Vitro Starch Digestibility of Commercial Gluten‐Free Pasta: The Role of Ingredients and Origin

“…Despite that, the remaining digestible starch had high levels of RDS. Marti and others (, ) proposed the use of cooking‐extrusion technology for improving the ancient noodle production technology, suggesting that the application of heating and cooling step promoted the formation of a product characterized by 2 regions: a core with remnant crystals and an amorphous external region (Marti and others , b; Barbiroli and others ). This structure likely accounts for the high levels of RS and RDS fraction assessed in oriental noodles.…”

Textural attributes of wheat and gluten free pasta

“…Rice parboiling can represent a preprocessing suitable by itself to induce a new macromolecular structure, able to assure good texture after cooking behavior in pasta products. The average molecular weight of amylose and amylopectin, as well as their molecular organization within the granule, affected starch functionality and, consequently, cooking performances (Marti et al, 2011b;2011c). The strong interactions of amylopectin and/or amylose promoted by the extrusion-cooking process suggested that in the product the amylopectin matrix is likely a combination of amylose and amylopectin chains.…”

Effect of iodine in semolina matrices

“…Although there is some evidence that starch-protein interactions interfere with glucan polymereiodine complex formation in a dilute solution (Liu et al, 2009), in a previous study it was demonstrated that the presence of components other than starch (such as proteins, lipids and nonstarch polysaccharides) did not interfere with the formation of granular starch-iodine complexes in gluten-free matrices (Marti et al, 2011). The objectives of the present research were to explore the possibility of investigating starch-protein interactions in a semolina matrix by using iodine vapor at low moisture contents.…”

“…These were chosen because of differences in the pasta-making performances (Alveographic W 165 Â 10 À4 J, 125 Â 10 À4 J, 198 Â 10 À4 J, and 154 Â 10 À4 J for Latinur, PR22D40, Semolina 1, and Semolina 2, respectively). Starch samples were isolated from semolina according to Park et al (2006). The nitrogen content of all starches was less than 0.1% (Dumas combustion method; Leco EP 528, Leco Instruments Ltd Canada).…”

“…Semolina samples and starch isolated from semolina were exposed to iodine vapor at 0.97 a w as described by Saibene and Seetharaman (2006). Wide-angle X-ray diffraction measurements were carried out on samples after equilibration at 0.97 a w , before and after iodine exposure (Rigaku Powder Diffractometer equipment -Rigaku Co., Tokyo, Japan), according to Marti et al (2011). The K/S value of the samples after iodine exposure was measured at wavelengths ranging from 400 to 700 nm, at 10 nm intervals, using a CM 3500-d Spectrophotometer (Konika Minolta, Mahwah, NJ, USA).…”