Valorization of winemaking residues as biochar for removing Ni(II) from real industrial painting process effluent in a fixed-bed column.

In this work, the adsorption of nickel ions from a real effluent from a metal-mechanic industry was investigated in a fixed-bed column using biochar. Biochar was prepared from winemaking residues originating from the Beifiur® composting process. The use of wine industry residues as precursor materials for biochar production is established in biomass residue valorization using the existing logistics and the lowest possible number of manipulations and pre-treatments. The results found in the work showed that the optimal conditions for nickel adsorption in fixed-bed columns were bed height (Z) of 7 cm, initial nickel concentration (C0) of 1.5 mg L-1, and flow rate (Q) of 18 mL min-1. In this condition, the maximum adsorption capacity of the column was 0.452 mg g-1, the mass transfer zone (Zm) was 3.3 cm, the treated effluent volume (Veff) was 9.72 L, and the nickel removal (R) was 92.71%. The Yoon-Nelson and BDST dynamic models were suitable to represent the breakthrough curves of nickel adsorption. Finally, the fixed-bed column adsorption using biochar from winemaking residues proved to be a promising alternative for nickel removal from real industrial effluents.

Impact of cooking temperature on the quality of quick cooking brown rice.

Three cooking temperatures (72, 80, and 88 °C) were applied to two rice genotypes (Puitá Inta CL and INOV CL) for preparing quick cooking brown rice. Samples were analyzed for cooking time, color, scanning electron microscopy (SEM), damaged grains, amylose, protein content and extractability, differential scanning calorimetry (DSC), X-ray diffraction (XRD), sensory properties, and in vitro digestion. Cooking time was reduced from 23.0-23.6 to 5.5-6.9 min when the highest temperature was applied, depending on genotype. The greatest grain deformation was observed for treatments from Puitá Inta CL. XRD showed greater ability of brown rice from Puitá Inta CL to gelatinize at 88 °C. Appearance, texture, and flavor of quick cooking brown rice prepared at 88 °C was inferior to its brown rice counterparts. Starch digestibility decreased by around 20-22% in 88 °C-prepared-quick cooking brown rice. Lower digestibility values were determined for 88 °C-treated-INOV CL, and were associated with grain integrity.

Immobilization of α-amylase in ultrafine polyvinyl alcohol (PVA) fibers via electrospinning and their stability on different substrates.

The objective of this study was to immobilize α-amylase in ultrafine polyvinyl alcohol (PVA) fibers by electrolysis and to evaluate its stability at different temperatures and pHs using various starch substrates such as corn starch and germinated and ungerminated wheat starches. The α-amylase-loaded ultrafine fibers were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), and loadability and enzymatic activity evaluations. Incorporation of the enzyme resulted in a slight change in fiber morphology; the fibers became flatter and thicker with increasing enzyme concentration. The mean diameters ranged from 187 to 282 nm. FT-IR spectra indicated that the enzyme was incorporated into the fibers. PVA showed a high loading capacity for α-amylase at all concentrations tested (1.0, 1.5, and 2.0% w/v), indicating that PVA is an excellent support. The enzymatic activity of α-amylase was tested on the different starch substrates; the activity was higher in the immobilized form than in the free form. Enzymatic immobilization improved the stability of α-amylase over a wide range of temperatures and pHs. Enzymatic activity was highest when germinated wheat starch was used as the substrate at different temperatures and pHs, indicating great potential for its application in hydrolysis with α-amylase.

Immobilization of xylanase and xylanase-ß-cyclodextrin complex in polyvinyl alcohol via electrospinning improves enzyme activity at a wide pH and temperature range.

Xylanase (EC 3.2.1.8) is a key enzyme for degradation of xylan. A limitation of xylanase application in food and beverage industries is the low enzyme activity and stability at a wide pH and temperature range. In the present study, different levels of pure xylanase (XY) and xylanase-ß-cyclodextrin (XY-ß-CD) inclusion complex were immobilized in polyvinyl alcohol (PVA) via electrospinning. Morphological and structural characteristics of obtained fibers were investigated by Fourier-transformed infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and X-ray diffraction (XRD) analyzes. Inclusion complex formation was evaluated by FTIR, XRD, and differential scanning calorimetry (DSC) analyzes. Obtained electrospun fibers showed a smooth surface with average diameter from around 200 to 600 nm. Greater diameters were observed at higher xylanase levels. In addition, inclusion complex provided thicker fibers than pure xylanase. Optimum xylanase activity changed from 60 to 70 °C when enzyme was immobilized in PVA. FTIR results suggest a more efficient enzyme conformation after immobilization. The greatest xylanase efficiency of immobilization was achieved at 0.5%-XY, with specific activity of 59.73 µM/min/mg of immobilized xylanase. Xylanase immobilized in PVA fibers exhibited higher activity at extremer pH conditions (4, 5, 7, and 8), as compared to free xylanase.