Development of an Oat-Based Biorefinery for the Production of l(+)-Lactic Acid by Rhizopus oryzae and Various Value-Added Coproducts

Abstract

A novel oat-based biorefinery producing L(+)-lactic acid and various value-added coproducts (e.g., beta-glucan, anti-irritant solution) is proposed. Pearling is employed for sequential separation of bran-rich fractions for the extraction of value-added coproducts. Lactic acid production is achieved via fungal fermentation of Rhizopus oryzae on pearled oat flour. Maximum lactic acid concentration (51.7 g/L) and starch conversion yield (0.68 g/g) were achieved when an oat flour concentration of 116.5 g/L was used. Oxygen transfer played a significant role with respect to lactic acid production and starch conversion yield. Rhizopus oryzae produced a range of enzymes (glucoamylase, protease, phosphatase) for the hydrolysis of cereal flour macromolecules. Enzyme production during fungal fermentation has been reported. The proposed biorefining strategy could lead to significant operating cost reduction as compared to current industrial practices for lactic acid production from pure glucose achieved by bacterial fermentations.

Effect of potentially probiotic lactic acid bacteria on the physicochemical composition and acceptance of fermented cereal beverages

“…This suggests that this fermented beverage could embrace greater flavour attributes as it has been reported that acetaldehyde is a major flavour component in yoghurt and other yoghurtrelated milks imparting a unique 'yoghurt' aroma (Coda et al, 2011;Ott, Fay, & Chaintreau, 1997;Ott, Germond, Baumgartner, & Chaintreau, 1999). The aroma of acetaldehyde has been described as 'green','ethereal' and 'pungent' (Koutinas, Malbranque, Wang, Campbell, & Webb, 2007). It has been observed that, during the fermentation of water-based cereal puddings inoculated with lactic acid bacteria the values of acetaldehyde were less than 1.0 mg/kg, and in milk-based cereal puddings the same strains produced acetaldehyde in concentrations that varied from 1.0 to 4.5 mg/kg (Helland et al, 2004).The rest of the cereal beverages had values of acetaldehyde from 0.13 to 0.24 mg/L.…”

ORIGINAL RESEARCH: Direct fermentation oftriticale starch to lactic acid byRhizopus oryzae

“…11,23 An oat starch conversion yield of 68 g LA/100 g starch was achieved in 10 L airlift bioreactors when spores were used as inoculum. 24 Sweet potato starch produced 72 g LA from 100…”

“…oryzae spores were inoculated into 100 mL of Vogel medium containing 3% (w/v) triticale starch at a final spore concentration at PEER REVIEW 1×10 4 per mL. One gram of sterile calcium carbonate powder was added to the culture medium at 0, 16,20,24, and 40 h during the fermentation at 28°C. To determine the effect of CaCO 3 dosage on LA production, different amounts of CaCO 3 were added to the medium 24 h after start of the fermentation.…”

Production of Chemicals from Biomass

“…Fermentative conversion of saccharides into platform chemicals would be dependent on the development of viable biorefineries (Koutinas et al, 2004a;Koutinas et al, 2004b;Webb et al, 2004;Koutinas et al, 2006;Koutinas et al, 2007a;Koutinas et al, 2007b;Koutinas et al, 2007c;Koutinas et al, 2007d). A generic strategy leading to fermentative conversion of various biomass resources into platform chemicals is shown in Figure 4.2.…”