Velásquez-Castillo Lía Ethel, Leite Mariani Agostinetto, Tisnado Victor Jesús Aredo, Ditchfield Cynthia, Sobral Paulo José do Amaral, Moraes Izabel Cristina Freitas
Postgraduate Program in Materials Science and Engineering, University of São Paulo, USP/FZEA, Av. Duque de Caxias Norte, 225, Pirassununga 13635-900, SP, Brazil.
Department of Food Engineering, Faculty of Animal Science and Food Engineering, University of São Paulo, Pirassununga 13635-900, SP, Brazil.
Foods. 2023 Jan 28;12(3):576. doi: 10.3390/foods12030576.
Quinoa starch nanocrystals (QSNCs), obtained by acid hydrolysis, were used as a reinforcing filler in cassava starch films. The influence of QSNC concentrations (0, 2.5, 5.0, 7.5 and 10%, /) on the film's physical and surface properties was investigated. QSNCs exhibited conical and parallelepiped shapes. An increase of the QSNC concentration, from 0 to 5%, improved the film's tensile strength from 6.5 to 16.5 MPa, but at 7.5%, it decreased to 11.85 MPa. Adequate exfoliation of QSNCs in the starch matrix also decreased the water vapor permeability (~17%) up to a 5% concentration. At 5.0% and 7.5% concentrations, the films increased in roughness, water contact angle, and opacity, whereas the brightness decreased. Furthermore, at these concentrations, the film's hydrophilic nature changed (water contact angle values of >65°). The SNC addition increased the film opacity without causing major changes in color. Other film properties, such as thickness, moisture content and solubility, were not affected by the QSNC concentration. The DSC (differential scanning calorimetry) results indicated that greater QSNC concentrations increased the second glass transition temperature (related to the biopolymer-rich phase) and the melting enthalpy. However, the film's thermal stability was not altered by the QSNC addition. These findings contribute to overcoming the starch-based films' limitations through the development of nanocomposite materials for future food packaging applications.
通过酸水解获得的藜麦淀粉纳米晶体（QSNCs）被用作木薯淀粉薄膜的增强填料。研究了QSNC浓度（0、2.5、5.0、7.5和10%，/）对薄膜物理和表面性能的影响。QSNCs呈现出圆锥形和平行六面体形状。QSNC浓度从0%增加到5%时，薄膜的拉伸强度从6.5 MPa提高到16.5 MPa，但在7.5%时，降至11.85 MPa。QSNCs在淀粉基质中的充分剥离也使水蒸气透过率降低了约17%（浓度达到5%时）。在5.0%和7.5%的浓度下，薄膜的粗糙度、水接触角和不透明度增加，而亮度降低。此外，在这些浓度下，薄膜的亲水性发生了变化（水接触角值>65°）。添加SNC增加了薄膜的不透明度，且未引起颜色的重大变化。其他薄膜性能，如厚度、水分含量和溶解度，不受QSNC浓度的影响。差示扫描量热法（DSC）结果表明，较高的QSNC浓度会提高第二玻璃化转变温度（与富含生物聚合物的相有关）和熔化焓。然而，添加QSNC并未改变薄膜的热稳定性。这些发现有助于通过开发用于未来食品包装应用的纳米复合材料来克服淀粉基薄膜的局限性。
