Influence Of The Sample Loading On The Contribution Of Competitive Effects For Granular Starch Exposed To Radio-Frequency Plasma

Plasma treatment can modify starch through two competitive reactions, crosslinking and depolymerization (degradation), depending on the experimental conditions. This work intends to clarify how the load of starch could play an important role in the dominant effect of the two reactions that occur during plasma treatment of starch. Therefore, different quantities of granular starch on the surface unit were exposed to the radio-frequency (RF) plasma under the same experimental conditions (13.56 MHz, 40 W, 10 min, in air). Properties such as pH, paste clarity, colorimetric and spectral features, and rheological behavior have changed with different patterns after exposure of starch to plasma, depending on the Sample loading. As a result, a process model was discussed. It considered hypothetically that only a layer of the sample surface was strongly degraded while the sample rest underwent the crosslinking process. It proved that crosslinking can occur preponderantly when the load of sample increases. Industrial relevance: Plasma treatment is an emerging and environmentally friendly method used recently to modify the functional properties of native starch. These changes are generally caused through two major competitive processes - crosslinking and degradation - depending on the experimental conditions (i.e., type of plasma generation, gas composition, sample preparation, voltage levels, exposure time). The question is whether the Sample loading, defined as the quantity of native starch placed as a uniform layer on the surface unit, might play a significant role in the predominant effect of these competitive reactions. Thus, in order to elucidate the role of the Sample loading as an input factor of the plasma treatment, we investigated the relationship between the induced-plasma effects and the Sample loading of granular starch. The findings showed that starch properties can be changed with different patterns after exposure of starch to plasma, depending on the Sample loading. A process model was brought to the reader's attention. It considered that only a layer of the sample surface was strongly degraded while the rest of the sample underwent crosslinking process. It proved that crosslinking can occur preponderantly when the load of the sample increases. Noteworthy that the Sample loading as an input factor must be taken into account in the technological design of starch exposure to plasma since it may significantly influence the manner in which starch is modified.