High moisture extrusion technology assisted by enzymatic protein-protein crosslinking approach to improve the texture of plant-based meat analalogues

目前，植物性肉类行业严重依赖添加剂的使用，包括调味料、着色剂、油以及结合和发质剂。结合和发质剂添加剂，如甲基纤维素、胶（如角胶、瓜尔胶、结冷胶、黄原胶、海藻酸盐）和纤维（如豌豆、燕麦、竹子），可以创造出类似肉类的质地，供冷热食用。消费者越来越希望有清洁标签和更健康的植物性食品。大量的研究已经表明，添加剂，如甲基纤维素（MC）是不可消化的，没有营养价值，长期摄入后可能会对健康产生不利影响。由于反应条件温和，酶的特异性，通过酶交联修饰植物蛋白结构正受到关注。由于蛋白质的功能是由其分子结构决定的，因此蛋白质的酶交联具有很大的潜力，可以在不需要使用MC、胶和其他添加剂的情况下产生不同的分子内和分子间键，从而获得质地和消费体验。探索由谷氨酰胺转胺酶等酶催化的蛋白质-蛋白质交联的作用，将有助于了解它对挤出植物蛋白的胶凝、乳化、发泡和变形特性的影响。最近的一项研究表明，通过谷氨酰胺转胺酶成功地将蚕豆和燕麦蛋白交联，提高了其静电稳定性。转谷氨酰胺酶诱导的凝胶也显示出高的最终储存模量和应变硬化响应，表明机械强织构。这表明具有良好胶凝能力的酶交联蛋白具有很高的潜力，可以替代常用的胶凝添加剂。蛋白质通过一系列增加分子间相互作用的过程转化为凝胶。突出的共价相互作用是二硫化物键；然而，植物蛋白的半胱氨酸含量有限，这有助于凝胶强度。转谷氨酰胺酶和其他氧化酶，如酪氨酸酶和漆酶，可以潜在地诱导食物蛋白质的交联，以改善质地特性。由于食物系统含有复杂的成分，并且涉及大量的加工，对酶交联蛋白质的最佳方式缺乏了解仍然是一个挑战。我们的目标是开发一种新型的无化学物质的植物性肉制品结合系统，以取代目前使用的商业粘合剂/添加剂。我们将在分子水平上对蛋白质和选定添加剂之间的相互作用进行系统的研究，以确切地了解如何为肉类类似物创造合适的质地。然后，我们将专注于蛋白质-蛋白质交联技术，作为挤压的预处理步骤，复制这种相互作用并重新创建无添加剂的肉状纹理。我们还将评估不同植物蛋白的交联性能、营养价值和成本，以实现最佳的清洁标签解决方案。研究objectives1。深入了解不同蛋白质（如豌豆，大豆，鹰嘴豆，蚕豆），酶（交联剂）的化学性质，以及如何使用添加剂开发当前肉类替代产品的质地。2.筛选测试的蛋白质，酶和加工参数，通过实验方法的结构化设计。生成预测模型，以实现交联蛋白基质的最佳性能（如纹理、脆性、弹性）。了解交联蛋白基质在模型植物性肉类配方中的表现，以及制造工艺参数（如挤压、高剪切混合、巴氏杀菌）的影响。进行广泛的产品验证程序（与行业伙伴合作），包括大规模生产试验和感官测试。

Currently plant-based meat industry heavily relies on using additives, including, flavourings, colouring, oil and binding & texturizing agents The binding & texturizing additives such as methylcellulose, gums (e.g. carrageenan, guar, gellan, xanthan, alginate) and fibres (e.g. pea, oat, bamboo) are to create the meat-like texture for cold & hot consumption. There is a growing desire from consumers to have clean label and heathier plant-based food. A significant number of studies already shown that additives, such as methyl cellulose (MC) is not digestible, doesn't have a nutritional benefit, & may have an adverse heath effect after prolonged ingestion Modifying the plant protein structure by enzymatic crosslinking is gaining an interest due to mild reaction conditions and the specificity of the enzymes. Since the functionality of a protein is determined by its molecular structure the enzymatic crosslinking of the protein has great potential to create different intra and inter molecular bonding to achieve texture and consumption experience without the need of using MC, gums and other additives. Exploring the effects of protein-protein crosslinking catalysed by enzymes such as transglutaminase, will be useful in understanding the effects it has on gelling, emulsifying, foaming, texturing properties of the extruded plant proteins.A recent study showed that faba bean and oat proteins were successfully crosslinked by transglutaminase which improved the electrostatic stability. Transglutaminase-induced gels were also shown to have a high final storage modulus & strain hardening response indicating mechanically strong texture. This demonstrates the high potential of enzyme crosslinked proteins with good gelling capability which can be an alternative to commonly used gelling additives.Proteins are converted to gels by a range of processes that increase intermolecular interactions. The prominent covalent interaction is disulfide bonds; however plant protein has limited amount of cysteine that contribute to the gel strength. Transglutaminase & other oxidative enzymes such as tyrosinase & laccase can potentially induce crosslinking of food proteins to improve textural properties A lack of understanding on the optimum way of crosslinking the proteins by enzymes remains a challenge as food systems contain complex ingredients and involves a lot of processing. We aim to develop a novel and chemical-free binding system for plant-based meat products as a replacement of currently used commercial binders/additives.We will conduct a systematic study on the interactions between proteins and selected additives at molecular level to understand exactly how to create suitable textures for meat analogues. We will then focus on protein-protein crosslinking technologies, as a pre-treatment step to extrusion, to replicate such interactions and re-create the meat-like texture without additives. We will also evaluate different plant based proteins for crosslinking performance, nutritional benefits, and costs to achieve the most optimal clean label solution.Research objectives1.Achieve in-depth understanding of the chemistry of different proteins (e.g. pea, soy, chickpea, faba), enzymes (crosslinkers), & how the texture of current meat-alternative products is developed using additives. 2.Screen the tested proteins, enzymes, and processing parameters, via a structured design of experiment methodology. Generate predictive models to achieve optimal performance (e.g. texture, brittleness, elasticity) of crosslinked protein matrix.3.Understand how crosslinked protein matrix behaves in model plant-based meat formula, & the impact of manufacturing process parameters (e.g. extrusion, high shear mixing, pasteurisation).4.Conduct an extensive product validation program (in collaboration with industry partner), including large scale manufacture trials and sensory testing.