Winemaking Waste Could Become Biofuel Starter

Grape pomace, the mashed up skins and stems left over from making wine and grape juice, could serve as a good starting point for ethanol production, according to a new study.

Due to growing interest in biofuels, researchers have started looking for cheap and environmentally sustainable ways to produce such fuels, especially ethanol. Biological engineer Jean VanderGheynst at the University of California, Davis, turned to grape pomace, because winemakers in California alone produce over 100,000 tons of the fruit scraps each year, with much of it going to waste.

To determine how much ethanol they could produce from pomace, VanderGheynst and her team processed pomace from the Sutter Home Winery in St. Helena, Calif., under various fermentation conditions. The researchers found that pomace from white grapes yielded the most ethanol. Winemakers only squeeze the juice out of these grapes and don’t ferment the pomace, so much of the fruits’ sugar remains. Meanwhile, red grape pomace has been fermented over long periods, so less sugar remains for ethanol production. But the scientists found that adding dilute acid to the red grape pomace boosted ethanol yields.

On average, the researchers found, grape pomace produces less than half as much ethanol as corn does by dry weight. To squeeze the maximum ethanol out of the grape waste, researchers would need to develop techniques to convert the grape’s cellulose into ethanol, says lead author Yi Zheng, a chemist at the biotechnology company Novozymes, in Denmark. But, he thinks pomace could still be a feasible feedstock because the material is readily available. Ethanol producers could make grape pomace more economically viable if they combined ethanol production with manufacture of other pomace-based products, such as fertilizers or animal feed, he says.

What Is Cellulose Microcrystalline?

Cellulose microcrystalline, referred as CEPO, is a widely used excipient, an inert substance used in many pill and tablet formulations. It is a white, odourless, tasteless, extra free flowing powder which is relatively free from organic and non-organic contaminants. The powder is metabolically inert, and has excellent water absorptive, swelling & dispersion properties, is insoluble in water, dilute acid, common organic solvents and oils.

It consists primarily of crystallite aggregates obtained by removing amorphous (fibrous cellulose) regions of a purified cellulose source material by hydrolytic degradation, typically with a strong mineral acid such as hydrogen chloride. The acid hydrolysis process produces a microcrystalline cellulose of predominantly coarse particulate aggregates, typically having a mean size range of about 15 to 40 microns.

Cellulose microcrystalline has many applications in pharmaceuticals, foods, papers and structural composites. It is a naturally derived stabilizer, texturizing agent, and fat replacer. The material is used extensively in reduced-fat salad dressings, numerous dairy products including cheese, frozen desserts and whipped toppings, and bakery products. It is made up of a chain of about 250 glucose molecules in the form of a microcrystal. In nature, several microcrystals are hinged together and surrounded by amorphous cellulose to form a microfibril. If it is removed, the resultant product is called level off DP (degree of polymerization) cellulose microcrystalline.

In addition, it is often used as a placebo in controlled drug studies. However, some side effects have been noted in animal studies, although usually at much higher dosages than would be normal for a human subject.

Some studies suggest that significant amounts of cellulose microcrystalline(CAS:9004-34-6) in the diet can promote weight loss, either by adding to a feeling of fullness or by reducing the absorption of other nutrients in the diet. However, the dosages at which these effects occurred were much higher than are found in most pharmaceuticals that use this excipient.

Because cellulose is not absorbed in the intestine, consumption of large amounts of it may increase the frequency and volume of bowel movements. However, the substance has less of an impact on bowel frequency and binding than do other forms of cellulose.