Potential of lactic acid bacteria to improve the fermentation and quality of coffee during on‐farm processing

This study describes, for the first time, the potential use of selected lactic acid bacteria (LAB) to conduct improved coffee bean fermentation during on‐farm wet processing. Among different strains tested, Lactobacillus plantarum LPBR01 showed a suitable production of organic acids and flavour‐active esters in a coffee‐pulp simulation medium and was used as starter culture under field conditions. The results indicated that L. plantarum LPBR01 was able to establish an accelerated coffee‐pulp acidification process and potentially reduced the fermentation time from 24 to 12 h. The inoculation of LPBR01 strain also increased significantly the formation of volatile aroma compounds during fermentation process (such as ethyl acetate, ethyl isobutyrate and acetaldehyde) and enabled the production of beverage with distinct sensory notes and a remarkable increase in quality compared to the conventional process. Our results suggest that the use of LAB in coffee processing is an ideal alternative way to conduct faster and improved coffee bean fermentation.     

Biotechnological process for producing black bean slurry without stachyose

Beans are important sources of proteins and other nutrients. However, stachyose and other oligosaccharides (RFOs) are present in this legume causing flatulence (H₂, CO₂ and CH₄), abdominal pain, and diarrhea. The problematic digestibility of these sugars in the small intestine is attributed to a lack of α-galactosidase, which is essential for the hydrolysis of α-1,6 linkages. The aim of the present work was to reduce the stachyose of black bean slurry by lactic acid fermentation using a selected Lactobacillus LPB56, an α-galactosidase producer. The bean slurry (6L) was fermented in a bioreactor with 1.3% (w/v) of CaCO₃, at 37 °C and 160 rpm. Bacterial cells increased from 2.4 × 10⁷ to 7.0 × 10⁸ CFU/mL, and the stachyose and other sugars were totally consumed after 18 h of fermentation. The maximum activity of α-galactosidase was 0.162 U/mL after 6 h. The fermentative process did not cause significant changes on the composition of the bean product.     

Enhancement of biohydrogen production in industrial wastewaters with vinasse pond consortium using lignin-mediated iron nanoparticles

The aim of this work was the enhancement of biohydrogen production by an anaerobic bacterial consortium with incorporation of lignin-mediated iron nanoparticles in the fermentation medium. Lignin magnetic nanoparticles (LMNP), identified as magnetite by XRD, exhibited spherical shape and average particle size of 8.6 nm, while lignin non-magnetic nanoparticles (LNMNP) exhibited high agglomeration and an amorphous nature in TEM and XRD, respectively. The fermentation medium (pH 7) was composed of 88% soft drink wastewater (SDW) and 12% corn steep liquor (CSL) and supplemented with NaHCO₃ (1.0 g/L) and cysteine-HCl (0.5 g/L). Under optimal conditions, BioH₂ production was 17.67 ± 0.54 mL, after 48 h of fermentation at 37 °C. Addition of LMNP and LNMNP increased BioH₂ production in 91.0 and 74.3%, respectively. Additionally, 200 mg/L of LMNP and LNMNP in the fermentation medium improved the BioH₂ yields (mL H₂/g COD_removed) in 2.8- and 2.3-fold, respectively.     

INCREASE IN PHYTASE SYNTHESIS DURING CITRIC PULP FERMENTATION

Citric pulp bran was used for the first time as substrate for phytase synthesis under solid-state fermentation. An A. niger FS3 phytase strain was applied in optimization studies. A Plackett-Burman screening design identified significant physicochemical variables. These preselected variables were subsequently optimized using a central composite rotational design (CCRD). The maximum phytase production was achieved with the following optimum variables: 30°C temperature, 65% initial moisture content, 0.3 M Na-citrate buffer concentration, initial pH 5.0, and 1.5% urea concentration. An overall 4.3-fold improvement in phytase production was successfully achieved.