Effects Of Drying Conditions On The Properties Of Plant Protein Films

Different drying methods and conditions have a significant impact on the propertiesofthe plant protein films and efficiency of the plant protein films formation process. In thisthesis, Soy Protein Isolate (SPI), Wheat Gluten (WG), zein were raw materials, and selectedthe appropriate process to obtain a film of protein solution, and then using water bathheating, blast heating, vacuum heating three ways by controlling various conditions to drythe liquid film. The difference of Tensile Strength (TS), Elongation (E), the Water VaporPermeability (WVP), water solubility and light transmission rate were determined theinfluence of different conditions. And preliminary researched the regularities of SPI filmsmoisture change during the drying process.The results showed that the drying rate by vacuum heating of three films was larger,but the drying rate by blast heating was the slowest at lower temperatures. As thetemperature increased, the drying time of the three drying methods were closer.The appropriate heating can improve the mechanical properties of the plant proteinfilms. As the temperature rised, the TS and E of the three films were increased at first andthen decreased in general. According to water bath and blast heating, the TS, E of SPI filmsand WG films reached a high value at60℃,70℃, zein films’ TS also reached a maximumvalue at70℃, but the E of zein films by blast heating reached a maximum value at80℃.The TS of SPI films were biggest at70℃by vacuum heating, but the E changed little withtemperature. The TS and E of WG films, zein films were the biggest at50℃.Considerate completely, the three films each selected three dry conditions, thendiscussed their impact on other properties of protein films. At the three conditions, for SPIfilms, the WVP was closed which drying under room temperature. For WG films, WVP waslower than which drying under normal room temperature, and for zein films, the WVP ishigher than which drying under normal room temperature. When temperature were70℃,the water vapor barrier property of WG films and zein films were strongest accordingvacuum heating. At the three conditions, the water solubility of SPI films was low and had little difference between which under normal room temperature. The water solubility of WGfilms which drying by water bath heating at60℃had little difference between which undernormal room temperature. But the water solubility of WG films which drying by water bathheating and blast heating at70℃was higher than which drying under normal roomtemperature, in addition, the water solubility of WG films was highest by water bathheating. Moreover, when temperature were70℃, the water solubility of WG films and zeinfilms were strongest according vacuum heating. The light transmission rate of SPI films,WG films, zein films under these drying conditions was lower than which drying undernormal room temperature; The light transmission rate of SPI films was lowest under blastheating at60℃, and had little difference conditions under two other drying conditions.When temperature were70℃, the light transmission rate of WG films and zein films werethe highest according water bath heating and the lowest according blast heating.Considering the drying time, cost, and the mechanical properties, WVP, watersolubility and light transmission rate of the films, the most suitable drying condition of SPIfilms, WG films and zein films was water bath at60℃, water bath at70℃, and water bathat70℃, respectively. Thethree filmsare more suitable for applications in three directions,respectively: require local high water solubility (such as instant noodles oil bag packaging,pharmaceutical packaging, etc.), a plastic packaging bags alternatives, require the strongability toresistant water (such as the product packaging which extent the shelf life,andpackaging ofdehydrated vegetables and seasoning powder, etc.).