Productions of biofuels (bioenergy processes) use biobased (sustainable) feedstocks, and convert energy — latent plant or algal molecules (formed by photosyn­thesis) to molecules more suited or amenable as fuels (see chapters 10,11,15,18—20 of this book). The key in­termediate, platform molecules of bioenergy processes, such as glucose for starchy or cellulosic bioethanol production, may be used to produce nonfuel biochemi­cals, such as organic acids, polyols, polymers or plastics (Clark et al., 2012; Dapsens et al., 2012; Koutinas et al., 2007, 2006). As the economics and scale of biofuel and biochemical productions continue to grow, it becomes more important to enhance the values of various co — and by-products, so that the biofuel or biochemical pro­duction can be upgraded or expanded to a more efficient biorefinery capable of maximally utilizing biobased feedstocks. Such expansion is desirable considering the colocation and energy/material source sharing, as well as the integrability of the existing phytochemical production technologies (mentioned in Section (Produc­tion of Industrial Phytochemicals)), with the bioenergy processes. Many approaches might be taken to recover phytochemicals during bioenergy or biochemical production processes. For instance, an upstream frac­tionation (e. g. dry milling or air classification) might be added to allow further processing of crudely sepa­rated feedstock components.

Coproduction from Starch — or Sugar-Based Bioenergy Processes

Starch — or sugar(cane)-based bioethanol processes are fully commercialized, and are the major bioethanol pro­viders at present. The main feedstocks are corn and sugarcane, and to a less extent, potato, cassava and sugar beet. Starch is converted by amylolytic enzymes to fermentable sugars (mainly glucose), sucrose is squeezed out from cane or beet, and sugars are fer­mented by yeast to ethanol. For corn ethanol processes, the main coproducts are DDGS for feed, as well as steep liquor, gluten meal, corn oil, and fiber from wet milling (Zhang et al., 2012, Figure 20.6). Main by-products are corn stover and cob for corn ethanol processes, and bagasse for sugarcane ethanol process. These by­products are currently being developed as feedstocks for lignocellulosic ethanol. Many phytochemicals of industrial interest might be obtained or derived from the co — or by-products of starch — or sugar-based bio­energy processes, as exemplified in Section (Coproduc­tion from Processing (Biorefinery) of Staple Crops). Obtaining betaine from sugar beet has been shown (Kripp, 2006). It has also been reported that polyolefins (e. g. polypropylene and polyethylene), polymerized polyurethane or other biomaterials may be made from DDGS (Diebel et al., 2012, Tatara et al., 2007; Chees — brough et al., 2008).