An attempt towards simultaneous biobased solvent based extraction of proteins and enzymatic saccharification of cellulosic materials from distiller's grains and solubles

Extraction of Polyphenols and Vitamins Using Biodegradable ATPS Based on Ethyl Lactate

The growing human population, together with the inefficient use of natural resources, has been dramatically increasing the production of food waste, which poses serious economic, environmental, and social problems. Being so, it is necessary to increase the efficiency of food consumption so as to reduce its waste and to convert the remaining residues into societal benefits. Since this biowaste is rich in polyphenols and vitamins, it could become the feedstock for the production of important value-added compounds for the pharmaceutical (e.g., food supplements) and cosmetic (e.g., creams and shampoos) industries. In this work, partition studies of one polyphenol (epicatechin) and two B-complex vitamins (cyanocobalamin and nicotinic acid) were performed in biodegradable Aqueous Two-Phase Systems (ATPS) based on ethyl lactate and on organic salts (disodium tartrate, tripotassium citrate, and trisodium citrate) at 298.15 K and 0.1 MPa. The largest partition coefficient (K) and extraction efficiency (E) were obtained for vitamin B12 (K=78.56, E=97.5%) for the longest tie line TLL=77.66% in the ATPS {ethyl lactate (1) + tripotassium citrate (2) + water (3)}. All the extractions were obtained with low biomolecule mass losses in quantification (<5%) and after a thorough study of pH influence in the UV−Vis absorbance spectra.

An integrative approach enables high bioresource utilization and bioethanol production from whole stillage

Bioethanol is a major biofuel in industry and mainly produced from corn starch with the dry-mill process. However, one of the remaining challenges is how to economically and efficiently exploit the wasted co-products to further improve ethanol production and generate more valuable chemicals. Here, an integrative approach was developed to efficiently utilize the waste cake for ethanol production, accompanied by protein extraction for feed additives. A high-quality protein feed was produced by the ethanol-alkali extraction method (extraction rate up to 46.91%). Notably, by applying two-step chemoenzymatic strategy, the supernatant and solid recycling yield up to 4.1-, 3.8-, and 154-fold improvements of ethanol, glucose, and xylose production, respectively, comparing to non-pretreatment. Moreover, mass balance analysis found this approach significantly contributed 1.74-4.42% (5.96-15.11 kg/ton dry corn) increase of total ethanol production. The gained knowledge about process design holds the potential transferability for other sustainable biowaste management and bioethanol industry.

Chemical composition of distillers grains, a review

In recent years, increasing demand for ethanol as a fuel additive and decreasing dependency on fossil fuels have resulted in a dramatic increase in the amount of grains used for ethanol production. Dry-grind is the major process, resulting in distillers dried grains with solubles (DDGS) as a major coproduct. Like fuel ethanol, DDGS has quickly become a global commodity. However, high compositional variation has been the main problem hindering its use as a feed ingredient. This review provides updated information on the chemical composition of distillers grains in terms of nutrient levels, changes during dry-grind processing, and causes for large variation. The occurrence in grain feedstock and the fate of mycotoxins during processing are also covered. During processing, starch is converted to glucose and then to ethanol and carbon dioxide. Most other components are relatively unchanged but concentrated in DDGS about 3-fold over the original feedstock. Mycotoxins, if present in the original feedstock, are also concentrated. Higher fold of increases in S, Na, and Ca are mostly due to exogenous addition during processing, whereas unusual changes in inorganic phosphorus (P) and phytate P indicate phytate hydrolysis by yeast phytase. Fermentation causes major changes, but other processing steps are also responsible. The causes for varying DDGS composition are multiple, including differences in feedstock species and composition, process methods and parameters, the amount of condensed solubles added to distiller wet grains, the effect of fermentation yeast, and analytical methodology. Most of them can be attributed to the complexity of the dry-grind process itself. It is hoped that information provided in this review will improve the understanding of the dry-grind process and aid in the development of strategies to control the compositional variation in DDGS.