Arêas J A
Dept. de Alimentos e Nutrição Experimental Faculdade de Ciências Farmacêuticas, USP, Brazil.
Crit Rev Food Sci Nutr. 1992;32(4):365-92. doi: 10.1080/10408399209527604.
Protein extrusion has frustrated earlier predictions regarding its impact in the development of food products. The main reason for this disappointing performance has been its failure to yield fabricated food products with textural quality close enough to that of natural products at competitive prices. Texturized soya protein by extrusion is presently the only commercial success in this area, being incorporated into several convenience products, increasing their protein content and quality and conferring them some desirable sensory properties. Technological and scientific gaps in the extrusion texturization are still to be bridged if this technique is to be applied for upgrading unconventional protein. The precise mechanisms responsible for protein texturization through extrusion are still unclear. Proteins show a very wide range of extrusion behavior that is probably related to large differences in their association properties. New peptide bonds, formed by free amino and carboxylic groups of the protein, were postulated as being responsible for the cross-linking that takes place in protein extrusion. However, disulfide bonds and electrostatic and hydrophobic interactions are regarded presently as the texturization mechanism in this process. The recently suggested suspension (or filled "melt") model for biopolymer extrusion offered a new framework for testing extrusion of novel proteins. According to this view, the large differences between the association properties of proteins produce different types of aggregates. Some of them can be insoluble under extrusion conditions and act as a dispersed phase within the melt phase. The extrusion performance of a protein will thus depend on the amount of insoluble aggregate produced inside the extruder and on protein-protein interactions that occur after the superheated molten mass leaves it.
蛋白质挤压技术在食品产品开发中的影响与早期预测相悖。其表现令人失望的主要原因在于，该技术无法以具有竞争力的价格生产出质地与天然产品相近的人造食品。目前，通过挤压制成的组织化大豆蛋白是该领域唯一取得商业成功的产品，已被应用于多种方便食品中，既能增加产品的蛋白质含量和质量，又赋予其一些理想的感官特性。若要将此技术应用于提升非常规蛋白质，挤压组织化过程中的技术和科学差距仍有待弥合。通过挤压实现蛋白质组织化的确切机制仍不明确。蛋白质呈现出极为广泛的挤压行为，这可能与其缔合特性的巨大差异有关。由蛋白质的游离氨基和羧基形成的新肽键被认为是蛋白质挤压过程中发生交联的原因。然而，目前二硫键以及静电和疏水相互作用被视为该过程中的组织化机制。最近提出的生物聚合物挤压悬浮（或填充“熔体”）模型为测试新型蛋白质的挤压提供了一个新框架。根据这一观点，蛋白质缔合特性的巨大差异会产生不同类型的聚集体。其中一些在挤压条件下可能不溶，并在熔体相中充当分散相。因此，蛋白质的挤压性能将取决于挤出机内产生的不溶性聚集体的数量，以及过热熔体离开挤出机后发生的蛋白质 - 蛋白质相互作用。
