Schmid Vera, Trabert Antje, Keller Judith Schäfer, Bunzel Mirko, Karbstein Heike P, Emin M Azad
Institute of Process Engineering in Life Sciences, Chair of Food Process Engineering, Karlsruhe Institute of Technology (KIT), 76131 Karlsruhe, Germany.
Institute of Applied Biosciences, Department of Food Chemistry and Phytochemistry, Karlsruhe Institute of Technology (KIT), 76131 Karlsruhe, Germany.
Foods. 2021 Feb 24;10(3):485. doi: 10.3390/foods10030485.
Food by-products can be used as natural and sustainable food ingredients. However, a modification is needed to improve the technofunctional properties according to the specific needs of designated applications. A lab-scale twin-screw extruder was used to process enzymatically treated apple pomace from commercial fruit juice production. To vary the range of the thermomechanical treatment, various screw speeds (200, 600, 1000 min), and screw configurations were applied to the raw material. Detailed chemical and functional analyses were performed to develop a comprehensive understanding of the impact of the extrusion processing on apple pomace composition and technofunctional properties as well as structures of individual polymers. Extrusion at moderate thermomechanical conditions increased the water absorption, swelling, and viscosity of the material. An increase in thermomechanical stress resulted in a higher water solubility index, but negatively affected the water absorption index, viscosity, and swelling. Scanning electron microscopy showed an extrusion-processing-related disruption of the cell wall. Dietary fiber analysis revealed an increase of soluble dietary fiber from 12.6 to 17.2 g/100 g dry matter at maximum thermo-mechanical treatment. Dietary fiber polysaccharide analysis demonstrated compositional changes, mainly in the insoluble dietary fiber fraction. In short, pectin polysaccharides seem to be susceptible to thermo-mechanical stress, especially arabinans as neutral side chains of rhamnogalacturonan I.
食品副产品可作为天然且可持续的食品成分。然而，需要根据特定应用的具体需求进行改性，以改善其技术功能特性。使用实验室规模的双螺杆挤出机对商业果汁生产中酶处理过的苹果渣进行加工。为了改变热机械处理的范围，对原料应用了各种螺杆转速（200、600、1000分钟）和螺杆配置。进行了详细的化学和功能分析，以全面了解挤出加工对苹果渣成分、技术功能特性以及单个聚合物结构的影响。在适度的热机械条件下进行挤出增加了材料的吸水性、膨胀性和粘度。热机械应力的增加导致更高的水溶解度指数，但对吸水指数、粘度和膨胀产生负面影响。扫描电子显微镜显示了与挤出加工相关的细胞壁破坏。膳食纤维分析表明，在最大热机械处理下，可溶性膳食纤维从12.6克/100克干物质增加到17.2克/100克干物质。膳食纤维多糖分析表明成分发生了变化，主要在不溶性膳食纤维部分。简而言之，果胶多糖似乎易受热机械应力影响，尤其是鼠李半乳糖醛酸聚糖I的中性侧链阿拉伯聚糖。
