Aspects on Starches Modified by Ionizing Radiation Processing

Abstract

Starch is one of the most studied natural polymers due to its widespread and applications as well as to the global interest regarding renewable, cheap, and easy to process resources. The native form of starch is frequently subjected to different processing methods in order to modify its structure and thus to obtain some functional properties suitable in specific industrial applications. Radiation-based method is a "green tool" for modification of natural polymers, such as starch, cellulose, pectin, and chitosan, alginate, having advantages over conventional methods that involve chemical agents associated with environmental toxicity. Radiation processing of natural polymers involves a simple, ecofriendly, and fast process that has harmless feature and provides advanced materials with unique properties. The chapter intends to be an overview of the major findings in the last decade concerning the starches modified by ionizing radiation processing. Therefore, aspects strongly related to changes in physicochemical, functional, and structural properties of starches from various botanical origins are approached. The main key points of this topic are highlighted by a critical evaluation of the mentioned aspects and future perspectives are suggested.

Electron beam irradiated maize starch: Changes in structural, physicochemical properties, and digestibility

“…Previous studies determined the changes in digestibility during irradiation (Polesi et al, 2018). Based on the results in this study, there were many factors affected on EB irradiated starch: (i) the depolymerization of starch molecules (Pimpa et al, 2007), (ii) the formation of cross-linkages causing the increase of DRC (Brașoveanu and Nemțanu, 2018), and (iii) the breaking down of large crystals to smaller ones (Brasoveanu et al, 2013). The increase of RDS could be elevated by depolymerization resulting in the formation of smaller molecules that were easily attacked by digestive enzymes.…”

“…In contrast, the dose of >9 kGy caused a decrease in DRC. Researchers found that the formation of cross-linkages in starch molecules leading to this increase (Brașoveanu and Nemțanu, 2018). Other researchers reported dose up to 50 kGy did not affect on DRC.…”

“…The nature of modification in starch by electron beam (EB) irradiation depends on various factors such as dose of irradiation, nature of irradiation, source of starches. Irradiation could be an effective treatment for starch modification through cross-linking, grafting and degradation reactions (Pimpa et al, 2007;Brașoveanu and Nemțanu, 2018). Base on determining factors (dose, moisture, rate) of EB treatment, most of the previous studies reported the effect of radicals on starch, resulting in changes in structure, physico-chemical properties and digestibility.…”

Water Absorption Kinetics in Composites Degraded by the Radiation Technique

“…A possible explanation for these results consists of the appearance of free radicals at the interaction between accelerated electrons and plasticized starch, which were able to induce molecular changes and fragmentation in starch molecule. Thus, by glycosidic linkage decomposition, the number of macromolecules having small chains increased, and smaller starch granules were formed [ 12 , 13 , 14 , 17 ]. Additionally, due to electron beam irradiation, both C–C and C–O scissions occurred.…”

“…In addition, the free radicals produced by irradiation in composites may contribute to the oxidation of functional groups, and the oxidized macromolecules can suffer chain cleavage with decreases in molecular weight [ 11 ]. For example, the effect of an accelerated electron beam on starch consists of glycosidic bond decomposition, which further leads to macromolecule decomposition and the appearance of molecules with smaller chains [ 12 , 13 , 14 , 15 ].…”