Fractionation and exploitation of the component value of DDGS

一些发酵过程，如酿造，使用谷物淀粉作为碳水化合物的来源。通常，谷物颗粒的残余物直到发酵过程结束才被分离。在酒精厂或生产燃料酒精的工艺中，液体物流然后经过蒸馏，留下液体残留物（“稀酒糟”）。在大规模操作中，液体和谷物残渣被干燥以生产可用作动物饲料的“干酒糟和可溶物”（DDGS）。在英国，至少有两个大型小麦酒精厂将很快投入运营。这些将把低级饲料小麦（英国通常有剩余）转化为酒精，用作汽车燃料，同时生产大量成分相当一致的DDGS。IBTI的工业成员提出了一个挑战，即为该DDGS增加价值，该项目解决了这一问题。除了淀粉，谷物主要由蛋白质、纤维和其他非淀粉碳水化合物和脂肪组成。主要的动物饲料价值包含在蛋白质中，但高纤维含量意味着DDGS仅适用于反刍动物。在这个项目中，我们打算分离一些蛋白质，碳水化合物和脂肪，并使用它们来生产更高价值的产品，同时仍然保留将蛋白质成分用作动物饲料的选择，可能用于家禽。后者很重要，因为使用DDGS作为动物饲料取代进口大豆，从而可以减少与大豆生产和进口相关的温室气体（GHG）排放。因此，挑战分为两个部分：1）设计从DDGS中去除非淀粉碳水化合物和脂肪的方法，而不破坏饲料价值，2）找到从提取组分中获得附加值的方法。对于第一部分，我们组建了一个多学科团队，他们是解决该项目工程，生物和动物营养组成部分的专家。从工艺工程的角度来看，在添加“可溶物”之前，使用分离的酒糟作为我们的起始材料实际上是有意义的。这是很难获得的，所以我们将从DDGS中回收谷物成分。可以用有机溶剂去除脂肪，但这可能会在动物饲料中留下不希望的残留物。作为替代方案，我们将研究使用超临界二氧化碳（SCCO 2）萃取;一种温和，无残留的方法，用于制作无咖啡因的咖啡。纤维和其他碳水化合物将主要通过酶去除，但我们需要找到温和的物理预处理（热水或短时间蒸汽处理），以促进酶接触碳水化合物。在（2）中，我们将专注于提升碳水化合物和蛋白质组分。碳水化合物可以用于第二次发酵过程，如果有生物可以将碳水化合物转化为有用的产品。为了降低这一过程的成本，我们需要找到/创造一种可以直接使用大部分碳水化合物聚合物的生物体，而不是添加单独的酶，因此该计划的这一部分将侧重于确定合适的酶和编码它们的基因，以将其放入已建立的过程生物体中。通过二次发酵生产额外的燃料或其他化学品不仅可以提高经济效益，还可以改善该过程的温室气体平衡。小麦籽粒中所含的蛋白质在组成上是相当专业的，具有高频率的某些氨基酸。大量供应为制造特定化学品提供了一个独特的机会，利用这种可再生化学品方法的可行性将包括第二类活动。如果成功，这也将产生温室气体效益。连同脂肪部分的预计用途，我们将把整个工作的联合收割机数据合并成一个经济模型，供潜在用户进行独立评价。

Some fermentation processes, eg brewing, use cereal starch as their source of carbohydrate. Typically, the residue of the cereal grain is not separated until the end of the fermentation process. In distilleries or in processes designed to produce alcohol for fuel, the liquid stream then goes through distillation which leaves a liquid residue ("thin stillage"). In large scale operations, the liquid and grain residues are dried to produce "distillers dried grain and solubles" (DDGS) which can be used as animal feed. In the UK, at least 2 large-scale wheat to alcohol plants will soon be operating. These will convert low-grade feed-wheat (of which the UK typically has a surplus) to alcohol for use as an automotive fuel, co-producing large quantities of DDGS, of a fairly consistent composition. The industrial members of IBTI have set a challenge of adding value to this DDGS, which this project addresses. Apart from the starch, cereal grain is composed mainly of protein, fibre and other non-starch carbohydrate and fats. The main animal feed value is contained in the protein, but the high fibre content means that DDGS is only useful for ruminant animals. In this project we intend to separate some of the protein, carbohydrate and fats and use them to produce higher value products, while still retaining the option to use the protein component as an animal feed, possibly for poultry. The latter is important as using DDGS as animal feed replaces imported soybean and thus, can reduce the greenhouse gas (GHG) emissions associated with soybean production and importation. Therefore, the challenge breaks down into 2 parts: 1) devising methods to remove the non-starch carbohydrate and fat from the DDGS without destroying the feed value, and 2) finding ways to gain added value from the extracted components. For the first part we have assembled a multidisciplinary team who are experts in addressing the engineering, biological and animal nutrition components of this project. From a process engineering perspective it would actually make sense to use the separated distiller's grain, before addition of the "solubles", as our starting material. This would be difficult to obtain, so we will recover the grain component from the DDGS. Removal of the fats could be done with an organic solvent, but this might leave undesirable residues in the animal feed. As an alternative we will investigate the use of super-critical carbon dioxide (SCCO2) extraction; a gentle, residue free method used for making decaffeinated coffee. The fibre and other carbohydrates will be removed mainly with enzymes, but we will need to find gentle physical pre-treatments (hot water or a short steam treatment) to facilitate enzyme access to the carbohydrates.In (2), we will focus on upgrading the carbohydrate and protein components. The carbohydrate could be used in a second fermentation process, if an organism was available that could convert the carbohydrates to useful products. To reduce the cost of this process we would need to find/create an organism that could use most of the carbohydrate polymers directly, rather than adding separate enzymes, so this part of the programme will focus on identifying suitable enzymes and the genes that encode them to put into established process organisms. Producing additional fuel or other chemicals by a secondary fermentation will not only improve the economics but also the GHG balance of the process. The proteins contained in wheat grain are rather specialised in their make-up, having a high frequency of certain amino acids. Availability in large volumes offers a unique opportunity to make specific chemicals, and the feasibility of exploiting this renewable chemicals approach will comprise a second strand of activity. If successful, this will also have a GHG benefit. Together with projected uses of the fatty fraction we will combine data from the whole exercise into an economic model for independent evaluation by potential users.