Farm‐scale production of fuel ethanol and wet grain from corn in a batch process

Abstract

The batch production of fuel grade ethanol and distillers' wet grain (wet solids) in a farm-scale process (1240-15,580 L/batch) is described. The employs yeast fermentation of amylase-treated corn mash and a two-stage distillation. Primary emphasis in this study was on the cooking, fermentation, and centrifugation steps. Without recycling, fermentation of the mash yield beers with 10.0-10.5% ethanol. Recycling of stillage supernatant at full, 75, or 50% strengths produced enriched mashes that after 48-h fermentation yielded beers with 5-;14% more ethanol. Recycling twice with full-strength supernatant at pH 7.0 increased the ethanol yield in the final beer 16.5%; however, the time to complete the final fermentation was extended form 48 to 72 h and salt buildup occurred. By recycling at pH 5.4, it was possible to avoid rapids salt buildup and obtain beers with 10.3-10.5% ethanol. Recycling resulted in increased levels of glucose, starch, crude protein, and fat in the beer and a reduced moisture content while the wet solids showed an increased starch content. Centrifugation after cooking or fermentation yield in the subsequently produced beer. Fermentation of a volume-resorted mash supernatant gave a beer with only 9.25% ethanol. Mash wet solids varied somewhat chemically from beer and stillage solids. An economic and energy balance analysis of various modes of plant operation are provided and plant considerations are suggested.

Seed‐specific expression of the wheat puroindoline genes improves maize wet milling yields

“…, 2007). In maize ethanol production, a batch method is generally used in which the amount of enzymes required as well as the time required for total conversion of starch to ethanol are two of the most important factors (Westby and Gibbons, 1982). We anticipate that ethanol production from dry milling processing could also be improved due to the use of softer textured PIN maize.…”

Development of a low-cost medium for production of nisin from Lactococcus lactis subsp. lactis

“…However, nisin titers were limited due to the low glucose concentration. CCS normally contains less than 10 g glucose/l (Westby and Gibbons 1982;Gibbons and Westby 1983), and we only supplemented with an additional 10 g glucose/l. Thus, if additional glucose or other suitable carbohydrates were added to CCS, it would not only be higher yielding than cheese whey, but could also produce higher concentrations of nisin at higher yield coefficients.…”

“…Removing this large amount of water consumes a tremendous amount of energy, and therefore using CCS or thin stillage as a nutrient source for a secondary fermentation is a desirable option (Bock et al 1997;Smith et al 2008). This material contains corn nutrients as well as yeast hydrolysate (Westby and Gibbons 1982;Gibbons and Westby 1983). In prior research with Clostridium thermoaceticum (Bock et al 1997) and Rhodospirillum rubrum (Smith et al 2008) we have shown that CCS can be a very effective replacement for yeast extract.…”

Effects of sodium meta bisulfite on diffusion fermentation of fodder beets for fuel ethanol production

“…In addition, yeast may have become more sensitive Figure 6 shows the effects of SMB makeup level on ethanol production during SBDF of the beet cube slurry. In the first batch of all four series, where 0.2% SMB was used, the maximum ethanol concentrations ranged from 4.2 to 5.2% (v/v) and production took 50-58 h. During subsequent batches (2)(3)(4)(5), ethanol levels increased until the concentration approached twice what it was in the first batch [i.e., 8-9% (v/v)]. This is the maximum ethanol concentration possible using the SBDF process, since ca.…”