BackgroundUS legislation requires the use of advanced biofuels to be made from non-food feedstocks. However, commercialization of lignocellulosic ethanol technology is more complex than expected and is therefore running behind schedule. This is creating a demand for non-food, but more easily converted, starch-based feedstocks other than corn that can fill the gap until the second generation technologies are commercially viable. Winter barley is such a feedstock but its mash has very high viscosity due to its high content of β-glucans. This fact, along with a lower starch content than corn, makes ethanol production at the commercial scale a real challenge.ResultsA new fermentation process for ethanol production from Thoroughbred, a winter barley variety with a high starch content, was developed. The new process was designated the EDGE (enhanced dry grind enzymatic) process. In this process, in addition to the normal starch-converting enzymes, two accessory enzymes were used to solve the β-glucan problem. First, β-glucanases were used to hydrolyze the β-glucans to oligomeric fractions, thus significantly reducing the viscosity to allow good mixing for the distribution of the yeast and nutrients. Next, β-glucosidase was used to complete the β-glucan hydrolysis and to generate glucose, which was subsequently fermented in order to produce additional ethanol. While β-glucanases have been previously used to improve barley ethanol production by lowering viscosity, this is the first full report on the benefits of adding β-glucosidases to increase the ethanol yield.ConclusionsIn the EDGE process, 30% of total dry solids could be used to produce 15% v/v ethanol. Under optimum conditions an ethanol yield of 402 L/MT (dry basis) or 2.17 gallons/53 lb bushel of barley with 15% moisture was achieved. The distillers dried grains with solubles (DDGS) co-product had extremely low β-glucan (below 0.2%) making it suitable for use in both ruminant and mono-gastric animal feeds.

The availability of winter barley in areas of the U.S. that are not well suited to grow corn, such as the mid-Atlantic states, makes it a feedstock of choice for fuel ethanol production in those regions. Recently, it was found that the Elusieve process, the combination of sieving and air classification (elutriation or aspiration), was effective in fiber separation from corn flour prior to fermentation. The objective of this study was to determine the effect of the Elusieve process on the compositions of fractions from barley flour of a hulled (Thoroughbred) and a hulless (Doyce) barley variety. The barley grains were milled using a hammer mill and sieved into four size fractions. Air classification of the two largest size fractions using a commercial aspirator resulted in heavier fractions with higher starch, higher beta-glucan, and lower neutral detergent fiber (NDF) contents. Hulls were preferentially carried into the lighter fractions, as signified by higher NDF contents of lighter fractions. Elusieve processing was more effective (higher separation factors) for the hulled variety than the hulless variety because higher hull presence caused increased carryover of hull into the lighter fractions for the hulled variety. The increase in beta-glucan and starch contents in barley flour, by hull separation using the combination of sieving and air classification, may increase ethanol productivity and may be beneficial in fuel ethanol production from barley when using a process that converts both starch and beta-glucans into fuel ethanol. Since the Elusieve process was most effective only when hulls were present, any dehulling operation prior to grinding would make Elusieve processing needless.

Pasteurization of raw goats' milk either at 63°C for 30 min or 72°C for 15 s within 1 d of milking ensures a better tasting product both initially and during storage at 4.5°C for 6 weeks than if the raw milk is aged for several days at 4.5°C before being pasteurized. Pasteurized milks processed from high-count raw milks aged 1 to 2 weeks had lower acceptability ratings (on a 9-point hedonic scale), which decreased further in cold storage and were independent of bacterial increases in the log phase of growth. Pasteurized milks processed from raw milk 7 or more days old were subject to rapid increases in bacterial numbers in storage if they were trace-contaminated during pasteurization even though initial counts were <100 psychrotrophs/ml. For all raw and pasteurized milks, three peaks were consistently observed from an HPLC analysis designed to monitor some organic acids. Two of the components decreased and the third appeared and increased during storage. Disappearance of one component coincided with appearance of another. These compounds may be associated with loss of flavor quality of the milk since in some instances these changes significantly correlated with the decrease in hedonic ratings of the stored milks.

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