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The bioresource utilization of herbal biomass residues (HBRs) has been receiving more attention. Herein, three different HBRs from Isatidis Radix (IR) and Sophorae Flavescentis Radix (SFR) and Ginseng Radix (GR) were subjected to batch and fed-batch enzymatic hydrolysis to produce high-concentration glucose. Compositional analysis showed the three HBRs had substantial starch content (26.36–63.29%) and relatively low cellulose contents (7.85–21.02%). Due to their high starch content, the combined action of cellulolytic and amylolytic enzymes resulted in greater release of glucose from the raw HBRs compared to using the individual enzyme alone. Batch enzymatic hydrolysis of 10% (w/v) raw HBRs with low loadings of cellulase (≤ 10 FPU/g substrate) and amylolytic enzymes (≤ 5.0 mg/g substrate) led to a high glucan conversion of ≥ 70%. The addition of PEG 6000 and Tween 20 did not contribute to glucose production. Furthermore, to achieve higher glucose concentrations, fed-batch enzymatic hydrolysis was conducted using a total solid loading of 30% (w/v). After 48-h of hydrolysis, glucose concentrations of 125 g/L and 92 g/L were obtained for IR and SFR residues, respectively. GR residue yielded an 83 g/L glucose concentration after 96 h of digestion. The high glucose concentrations produced from these raw HBRs indicate their potential as ideal substrate for a profitable biorefinery. Notably, the obvious advantage of using these HBRs is the elimination of the pretreatment step, which is typically required for agricultural and woody biomass in similar studies. [ABSTRACT FROM AUTHOR]

Microorganisms can produce many antibiotics against bacteria and fungi, which have been used as a potential choice of new antibiotics. In this paper, we studied the characteristics of antibacterial substances by Bacillus cereus BC1. The results showed that the acid-precipitated substance played the main role in antibacterial activity, and further characterization indicated that the antibacterial substance might be a lipopeptide substance. Then the antibacterial spectrum suggested that the antibacterial substance had an inhibitory effect on Gram-positive bacteria and fungi, while selenium-riched antibacterial substance of Bacillus cereus BC1 could significantly enhance the inhibition. Then the morphological effects of the antibacterial substance to indicator bacteria were determined. The effects of different treatment methods on the stability of antibacterial substances were studied and the results showed that the antibacterial substance was stable to heat, ultrasonic, and ultraviolet treatment, and their antibacterial activity would not be greatly affected. However, they were sensitive to pepsin. The optimum pH range of antibacterial activity was 3–5. This study may contribute to reusing the fermentation supernatant often discarded in the previous fermentation process. At the same time, the lipopeptide antibacterial substance extracted from the fermentation broth of selenium-enriched Bacillus cereus BC1 can be used in the development of antibiotics and biopesticides, and open up a new way for the control of plant diseases. [ABSTRACT FROM AUTHOR]

Tribonema biomass is considered promising biorefinery feedstock for the co-production of biodiesel and valuable bioproducts; however, the extraction of these useful compounds produces large amounts of algal residues, which produce increased environmental concerns. Herein, cellulose was extracted from the waste residue of T. utriculosum via alkalization and bleaching, followed by the production of high-value-added cellulose nanocrystals (CNCs) via acid hydrolysis. The hydrolysis was performed with 60% (wt%) H2SO4 at a yield of 13.31%, resulting in the generation of rod-shaped nanoparticles averaging 39.5 nm in diameter and 239.2 nm in length. The structural characterization analysis revealed that the prepared CNCs had high crystallinity (73.0%) due to the removal of non-cellulose components and amorphous regions by chemical treatment, as well as possessing good aqueous suspension stability (zeta potential = – 40.1 mV). Although the CNCs showed lower thermal stability than extracted cellulose, they spanned a broader temperature range due to two-stage degradation behaviour, with higher residue weight (16.7%). This work represents the first report on the preparation of a high-value-added industrial product, CNCs, from the filamentous microalga T. utriculosum, aiming to maximize benefits from waste algal residue reutilization. [ABSTRACT FROM AUTHOR]

A growing interest has been shown regarding the impact of α-amylase on the quality of fermented foods. Therefore, the interaction between γ-cyclodextrin and α-amylase was investigated in this article. The results showed that γ-cyclodextrin had an inhibitory effect on the activity of α-amylase under certain conditions, obtaining the strongest inhibitory effect when the concentration of γ-cyclodextrin was 10 mmol/L, the reaction temperature was 45 °C, pH = 5.9 and reaction time of 120 min. The results also showed important changes in the secondary structure of α-amylase induced by γ-cyclodextrin, including the transformation of α-helix, β-fold and random coil. Moreover, the addition of γ-cyclodextrin could induce the change of endogenous fluorescence intensity by changing the microenvironment of the α-amylase. According to the results of NMR, a part of the α-amylase molecule enters the cavity of the γ-cyclodextrin, and the other part forms a hydrogen bond with the outer cavity, forming a complex. The experimental results provide references for the application of γ-cyclodextrin and α-amylase. [ABSTRACT FROM AUTHOR]

This paper reports computational fluid dynamics (CFD) studies on the performance of flow inside a rotating disk filtration module. This module consists of a disk rotating at speeds between 1000 and 3000 rpm inside a cylindrical housing equipped with a stationary circular flat membrane. In order to investigate the influence of surface geometry, a smooth disk and a disk equipped with vanes were used. Commercial CFD software was utilized for the characterization of the flow inside the membrane module. The predicted results were compared at different values of rotating and inlet velocities with previous works and also with experimental ones obtained in the filtration of dairy effluent in the same conditions. The influence of the geometry of the disk was also evaluated. The obtained results show that an increase in rotating velocity leads to an increase in the pressure and shear stress at the membrane surface. The highest pressures were obtained when using disks equipped with vanes, this was due to the turbulent area created between the vanes visualized in animated views. It was also found that the presence of vanes on the surface of disk has a great effect on the shear stress; it contributes to the reduction in fouling and improvement in filtration flux. [ABSTRACT FROM AUTHOR]

Jerusalem artichoke is an important plant for industrial inulin production. Jerusalem artichoke extract was clarified by ultra-filtration. Tests were performed to investigate effects of membrane pore size and operation conditions (trans-membrane pressure and rotation speed) on filtration kinetics and membrane-fouling mechanism. Membrane fouling was proved the main filtration resistance for a 20-kDa membrane, while concentration polarization-induced resistance was dominant for 30-, 50-, and 100-kDa membranes. Despite their similar filtration behavior, the 50-kDa membrane, compared to the 100-kDa membrane, led to less protein content (impurity) in the filtrate. Studies with the rotation speed varied from 0 to 1600 rpm and trans-membrane pressure from 0.2 to 0.4 MPa demonstrated that stirring was essential for elimination of membrane fouling. Competition of driving force and fouling was justified when trans-membrane pressure increased from 0.3 to 0.4 MPa. Filtrate analysis including protein removal, turbidity, and inulin purity revealed that ultra-filtration using the 50-kDa membrane with a trans-membrane pressure of 0.3 MPa and a rotation speed of 800 rpm was able to clarify the Jerusalem artichoke extract, removing 99% protein, and obtain a filtrate with inulin purity of 98%. [ABSTRACT FROM AUTHOR]

α-amylase activity influences both flour fermentation process and the quality of the fermented products due to its ability of breaking starch into smaller units. The inhibition of cyclodextrins on α-amylase activity was investigated in this paper. Experiment results showed that hydrophobic cavity size was an intrinsic factor during the inhibition processing. Among three types of cyclodextrin (α-, β- and γ-), β-type exhibited the most significant inhibitory activity toward α-amylase. The optimal inhibitory parameters were indicated to be pH 5.9, concentration of β-cyclodextrins 1 mmol/L, reaction temperature 45 °C and reaction time 60 min. Results suggested that the endogenous fluorescence of α-amylase was inhibited by cyclodextrins. Circular dichroism spectrum indicated that the secondary structure of α-amylase, including α-helices, β-sheets and random coils, was changed by cyclodextrins. All the results in this paper aim to provide a further understanding for α-amylase in the industry application. [ABSTRACT FROM AUTHOR]

Rotating disk module (RDM)-assisted cross-flow ultrafiltration of sugar beet juice, obtained by cold pulsed electric field-assisted pressing, was studied in full recycling and concentration modes. Results of trans-membrane pressure (TMP) stepping tests with 10- and 50-kDa membranes showed that filtration flux increased with rotation speed and TMP until 1000 rpm and 4 bar. A slight variation of filtration purity was observed for a rotation speed range of 0-2500 rpm. A TMP increase resulted in purity reduction due to the formation of thicker fouling layer. A full recycling test study with a 10-kDa membrane confirmed the influence of TMP and rotation speed on filtration flux. A rotation speed of 1000 rpm and a TMP of 4 bar were selected for sugar beet juice purification, by concentrating juice from 13 to 1 L. The results of concentration mode tests revealed that, with a 10-kDa membrane, the filtrate purity could reach 95.6 ± 0.5 %, which was comparable to the purity of sugar beet juice purified by conventional liming-carbonation method. The flux decline in cross-flow filtration was still important, justifying more effective anti-fouling technologies investigation. [ABSTRACT FROM AUTHOR]

Pulsed ultrasound-assisted extraction with water was carried out to extract valuable compounds from purple sweet potato (PSP). Quality properties and dead-end filtration of PSP extract were investigated. Solutes concentration in PSP extract were 118.60 ± 2.83, 599.8 ± 8.28, and 0.72 ± 0.03 μg mL for total protein, total polyphenol, and total anthocyanin, respectively. Filtration with PES 50 kDa membrane-augmented polyphenol purity from 83.4 % in extract to 99.6 %. A protein removal coefficient of 99 % was achieved. Resistance in series model and Hermia's model was applied to quantify filtration resistance and investigate fouling mechanism during filtration. Gel layer resistance was the most important for all three used membranes (PES 0.1 μm, PES 100 kDa, and PES 50 kDa). Fitting of experimental data by Hermia's model revealed that the most suitable fouling mechanism varied, cake layer model for PES 0.1 μm and PES 100 kDa membrane and intermediate blocking model for PES 50 kDa membrane. For the purpose of more efficient polyphenol production, advanced filtration modules, such as cross-flow and rotating disk filtration module, are expected. [ABSTRACT FROM AUTHOR]

Membrane dead-end ultrafiltration of sugar beet juice (obtained from pulsed electric field assisted nonthermal pressing) was studied as an alternative method to the conventional liming-carbonation purification. A dead-end filtration module, Amicon 8200, was first used to investigate the purification efficiency of ultrafiltration with various polyethersulfone membranes (10 kDa, 50 kDa, and 150 kDa). The purity of sugar beet juice was increased from 93.6 ± 0.5 to 96.4 ± 0.8 % with a 10-kDa membrane. In order to improve the filtration flux, which declined tremendously during dead-end filtration due to membrane fouling, a rotating disk module (RDM) was then applied, and the investigation of the dynamic filtration behavior and filtrate quality of sugar beet juice was carried out. Compared with Amicon stirred module, the RDM had a much higher permeate flux and filtrate purity. The effect of rotating speed and molecular weight cutoff (MWCO) of membranes were studied. The permeate flux increased with rotating speed and pore size of membrane. The permeate flux increased significantly when the rotating speed was raised from 500 to 1,000 rpm, while it slightly increased at higher rotating speed (2,000 rpm). The purification efficiency of dynamic RDM filtration was about twice than that of filtration performed with Amicon stirring module. [ABSTRACT FROM AUTHOR]

Selenylation modification is an effective way to improve the nutritional and health effects of tea polysaccharide, but the effects of different selenylation methods on the structure and efficacy of polysaccharides remain unclear. In this study, a series of chemically selenized tea polysaccharides (CSe-TPS, selenium content of 129.98 ~ 1454.99 µg/g) were prepared by Na2SeO3-HNO3 method, which were promoted by heating (HCSe-TPS), ultrasound (UCSe-TPS), and pulse electric field (PCSe-TPS) treatments, respectively. These different CSe-TPSs were systematically compared with ordinary tea polysaccharides (Ord-TPS) and natural selenium-enriched tea polysaccharides (NSe-TPS) in aspect of molecular structure and biological functions. The results of molecular structure and apparent morphology showed that the particle size (p < 0.05) and the thermal stability of Ord-TPS were reduced after selenylation modification, while the absolute potential of polysaccharide was increased (p < 0.05), coupled with altered monosaccharide composition and changed apparent morphology. However, the main functional groups and the secondary structure of Ord-TPS did not change. The antioxidant activities of tea polysaccharides after selenylation were improved as well as their inhibitory effects on carbohydrate digestive enzymes (p < 0.05). The total antioxidant capacity of PCSe-TPS (selenium content of 240.66 ± 1.43µmol/g) was enhanced by 85.41% compared with Ord-TPS (selenium content of 129.80 ± 3.42 µmol/g), while its IC50 values on inhibition of α-amylase (2.91 ± 0.18 mg/mL) and α-glucosidase (0.18 ± 0.01 mg/mL) were significantly lower than other tea polysaccharides (p < 0.05), which suggested best antioxidant and hypoglycemic activity. Moreover, tea polysaccharides with higher selenium content and smaller particle size showed better antioxidant and hypoglycemic activities. This research will provide new strategies for the application of tea polysaccharides. [ABSTRACT FROM AUTHOR]