Food waste is a global problem, causing significant environmental harm and resulting in substantial economic losses globally. Bread is the commonly wasted food item in the developed world and presents a severe problem for the majority of European nations. It is the second most wasted food item in the UK after potatoes, with an equivalent of 20 million slices of bread thrown away daily. Bread is a starchy material and a rich and clean source of easily extractable fermentable sugars – this is in direct contrast to lignocellulosic feedstocks where harsh physical, chemical and/or enzymatic pretreatment processes are required for release of fermentable sugars. Furthermore, these necessary lignocellulosic pretreatment methods often produce sugars contaminated with fermentation inhibitors. Therefore, bread waste presents a clear opportunity as a potential carbon source for novel commercial processes and, to this end, several alternative routes have been developed to utilize bread waste. Possibilities for direct recycling of bread waste within the food industry are limited due to the relatively short material lifetime, stringent process and hygiene requirements. Anaerobic digestion (AD) and incineration are commonly employed methods for the valorisation of bread waste, generating limited amounts of green energy but with little other environmental or economic benefits. Most food wastes and by-products in the UK including bakery waste are treated through AD processes that fail to harness the full potential of the these wastes. This short communication reviews the challenges of handling bread waste, with a focus on a specific UK scenario. The review will consider how bread waste is generated across the supply chain, current practices to deal with the waste and logistics challenges in waste collection. The presence of clean and high-quality fermentable sugars, proteins and other nutrients in bread make it an ideal substrate for generating chemicals, fuels, bioplastics, pharmaceuticals and other renewable products through microbial fermentations. We suggest potential applications for recycling bread waste into its chemical building blocks through a fermentative route where a circular biorefining approach could maximize resource recovery and environmental savings and eliminate waste to as close to zero as possible.

中文翻译：

---

使用循环生物精炼方法将面包废料回收成化学原料

食物浪费是一个全球性问题，造成严重的环境危害并在全球范围内造成巨大的经济损失。面包是发达国家普遍浪费的食品，对大多数欧洲国家来说是一个严重的问题。它是英国第二大浪费食品，仅次于土豆，每天扔掉的食物相当于 2000 万片面包。面包是一种淀粉材料，是易于提取的可发酵糖的丰富而清洁的来源——这与木质纤维素原料形成鲜明对比，木质纤维素原料需要严酷的物理、化学和/或酶促预处理过程来释放可发酵糖。此外，这些必要的木质纤维素预处理方法常常产生被发酵抑制剂污染的糖。因此，面包废料作为新型商业流程的潜在碳源提供了明显的机会，为此，已经开发了几种利用面包废料的替代途径。由于材料寿命相对较短、工艺和卫生要求严格，食品工业中直接回收面包废料的可能性受到限制。厌氧消化（AD）和焚烧是面包废物增值的常用方法，产生的绿色能源数量有限，但几乎没有其他环境或经济效益。英国的大多数食物垃圾和副产品（包括烘焙垃圾）都是通过厌氧消化工艺进行处理的，但无法充分利用这些废物的潜力。这篇简短的交流回顾了处理面包废物的挑战，重点关注英国的具体情况。该审查将考虑整个供应链中面包废物是如何产生的、处理废物的当前做法以及废物收集中的物流挑战。面包中含有清洁、优质的可发酵糖、蛋白质和其他营养物质，使其成为通过微生物发酵生产化学品、燃料、生物塑料、药品和其他可再生产品的理想基质。我们建议通过发酵途径将面包废物回收为其化学构件的潜在应用，其中循环生物精炼方法可以最大限度地提高资源回收和环境节约，并将废物消除到尽可能接近于零。