Modulating digestibility and stability of Pickering emulsions based on cellulose nanofibers

Cellulose nanofibers (CNF) have been widely studied for their biodegradability and for their unique advantages as a stabilizer in Pickering-type emulsions. However, it is challenging to produce cellulose nanofibers from agroindustry waste with good techno-functional properties, without the use of harsh process conditions. Green alternatives (eco-friendly) have been studied to obtain nanofibers, such as enzymatic hydrolysis and/or application of mechanical processes. In this work, we used acid hydrolysis (as a control and example of an efficient method), enzymatic hydrolysis and a mechanical process (ultrasound) to obtain cellulose nanofibers. We also evaluated the effect of the presence of ethyl groups in the cellulosic matrix (ethylcellulose) on the stabilizing mechanism of emulsions. All cellulose nanofibers were able to produce Pickering emulsions at concentrations of 0.01-0.05% (w/w), although showing differences in emulsion stability and digestibility. Morphology of the different cellulose nanofibers affected the viscosity of the aqueous suspensions used as continuous phase. Emulsions with nanofibers obtained from cassava peel (without the presence of ethyl groups) were stabilized only by the Pickering-type mechanism, while ethylcellulose nanofibers also showed surface activity that contributed to the stability of the emulsion. Furthermore, these latter emulsions showed greater release of free fatty acids in in vitro digestion compared to emulsions stabilized by cellulose nanofibers. Despite these differences, in vitro digestion showed the potential of applying cellulose-stabilized emulsions to control the rate of lipid digestion, due to the low amount of free fatty acids released (<20%).

Comparison of methods for detecting protein extracted from excess activated sludge

The protein contents of hydrolyzed sludge supernatant are commonly determined with the Kjeldahl method, but this method suffers from complicated operations, long process times, and large quantities of chemicals consumed. In this paper, the Lowry, bicinchoninic acid (BCA), and Bradford methods were used to test the precision and spiked recovery of proteins from sludge supernatants hydrolyzed by alkaline-thermal hydrolysis (ATH), enzymatic hydrolysis (EH), and ultrasound-assisted enzymatic hydrolysis (UEH), and the results were compared with those obtained with the Kjeldahl method. For all the hydrolytic processes, the sludge protein values determined with the three tested methods were within 0.05 of each other, which met the experimental requirement for accuracy. Both the Lowry and BCA methods had recovery rates of 95-105%, while the Bradford method showed large deviations and was not highly reliable. The three protein determination methods showed significant differences with the Kjeldahl method (P<0.05). However, the relative deviation between the Kjeldahl and BCA methods was the smallest (3-5%), followed by those between the Kjeldahl and the Lowry (11-21%) and Bradford methods (21-90%), and the causes of the deviations were analyzed based on the protein hydrolysate components and the mechanisms for the different detection methods. On the basis of these results, the BCA method was chosen as the most appropriate quantification method for use with sludge protein extraction, and it was used to analyze the protein contents extracted from residual sludge samples obtained from two sewage treatment plants. The reliability of the method was verified, and this lays a foundation for the extraction and reclamation of sludge proteins.

Steroidal alkaloids and their glycosides from the bulbs of Fritillaria unibracteata

Seven undescribed steroidal alkaloids, including two jervine-type steroidal alkaloids, fritiunibras A-B (1-2), and five cevanine-type steroidal alkaloid glycosides, fritiunibras C-G (3-7), along with six known cevanine-type steroidal alkaloids and their glycosides (8-13) were isolated from the bulbs of Fritillaria unibracteata Hsiao et K. C. Hsia. Their structures were determined by interpretation of comprehensive spectroscopic and single-crystal X-ray diffraction analysis. The absolute configurations of sugar moieties were determined by HPLC analysis and compared with standards after hydrolysis and derivatization. Furthermore, their inhibitory effects on NO production and cytotoxic activities were evaluated.

Phenolic glycosides from the stems of Homalium stenophyllum

The phytochemical investigation of the stems of Homalium stenophyllum afforded seven new phenolic glycosides (1-5 and 8-9) and two known compounds (6 and 7). Their structures were elucidated by comprehensive analyses of NMR spectroscopic, mass spectrometric data and chemical hydrolysis. Additionally, their anti-inflammatory activities against the NO production in LPS-induced macrophages were evaluated.

Improvement of methanogenic activity of anaerobic digestion using poly(l-lactic acid) with enhanced chemical hydrolyzability based on physicochemical parameters

Because packing bags and disposable items of poly (l-lactic acid) (PLLA) waste are discharged together with other organic waste including garbage, anaerobic co-digestion of PLLA and other organic waste is required. However, because of low hydrolyzability of PLLA products, the chemical hydrolyzability must be improved for PLLA treatment during anaerobic digestion. This study aimed to assess weight-average molecular weight (M_w) and crystallinity (X_c), to determine the chemical hydrolyzability of PLLA, for PLLA treatment during anaerobic digestion. Moreover, the possibility of anaerobic co-digestion of the PLLA after improvement of chemical hydrolyzability and other organic waste was also discussed. Detectable methanogenic activity of the mesophilic and thermophilic anaerobic sludges of PLLA occurred in the M_w range of 6,800 to 16,500, and 6,800 and 38,000, respectively. The methanogenic activity of mesophilic and thermophilic anaerobic sludge was higher with PLLA with a high crystallinity (X_c = 39.9-46.1%) than with nearly amorphous PLLA (X_c = 0.3-3.5%). The maximum methanogenic activity of anaerobic sludge using PLLA with an X_c of approximately 40-45% and with a M_w of 10,300 and 16,500 for mesophilic and thermophilic anaerobic sludge were 0.013 gCOD·gVS^-1·d^-1 and 0.13 gCOD·gVS^-1·d^-1, respectively. A survey on the possibility of anaerobic co-digestion of PLLA after improvement in chemical hydrolyzability based on M_w and X_c and organic wastes revealed that thermophilic conditions at 55 °C are more advantageous than mesophilic conditions at 37 °C.

Sorption and degradation of carbaryl in soils amended with biochars: influence of biochar type and content

Biochars that were produced from three different biomass materials were amended to a soil to elucidate their influence on the fate of carbaryl. Sorption and degradation of carbaryl in soils amended with the biochars were investigated. The results showed that the amendment of biochars to soil enhanced the sorption of carbaryl. The nonlinearity of sorption isotherm and sorption affinity of carbaryl increased with the content and pyrolytic temperature of the biochars. Both chemical and biological degradation of carbaryl were influenced by biochars. The biochars enhanced the chemical hydrolysis of carbaryl in soil, with biochars produced at 700 °C (BC700) exhibiting greater impact, due to their strong liming effect. In contrast, BC350 (produced at 350 °C) promoted the biodegradation of carbaryl in soil by different extents, while BC700 obviously reduced the biodegradation of carbaryl. The enhanced activities of natural microorganisms in the soil and the lowered bioavailability of carbaryl acted together to determine the biodegradation.

High-yield production of biosugars from Gracilaria verrucosa by acid and enzymatic hydrolysis processes

Gracilaria verrucosa, the red alga, is a suitable feedstock for biosugar production. This study analyzes biosugar production by the hydrolysis of G. verrucosa conducted under various conditions (i.e., various acid concentrations, substrate concentrations, reaction times, and enzyme dosages). The acid hydrolysates of G. verrucosa yielded a total of 7.47g/L (37.4%) and 10.63g/L (21.26%) of reducing sugars under optimal small (30mL) and large laboratory-scale (1L) hydrolysis processes, respectively. Reducing sugar obtained from acid and enzymatic hydrolysates were 10% higher, with minimum by-products, than those reported in other studies. The mass balance for the small laboratory-scale process showed that the acid and enzymatic hydrolysates had a carbohydrate conversion of 57.2%. The mass balance approach to the entire hydrolysis process of red seaweed for biosugar production can be applied to other saccharification processes.

Contribution of acetic acid to the hydrolysis of lignocellulosic biomass under abiotic conditions

Acetic acid was used in abiotic experiments to adjust the solution pH and investigate its influence on the chemical hydrolysis of the Organic Fraction of Municipal Solid Waste (OFMSW). Soluble chemical oxygen demand (SCOD) was used to measure the hydrolysis under oxidative conditions (positive oxidation-reduction potential values), and pH 4 allowed for 20% (±2%) of the COD added to be solubilized, whereas only 12% (±1%) was solubilized at pH7. Under reducing conditions (negative oxidation-reduction potential values) and pH 4, 32.3% (±3%) of the OFMSW was solubilized which shows that acidogenesis at pH 4 during the anaerobic digestion of solid waste can result in chemical hydrolysis. In comparison, bacterial hydrolysis resulted in 54% (±6%) solubilization.

Development of complete hydrolysis of pectins from apple pomace

Enzymatically extracted pectins have a more complex structure than those obtained by conventional methods. As a result, they are less susceptible to hydrolysis, which makes the precise determination of their composition difficult. The aim of the study was to develop a method of complete hydrolysis of enzymatically extracted apple pectins. Substrates were pectins isolated from apple pomace by the use of xylanase and multicatalytic preparation Celluclast and apple pomace. Hydrolysis was performed by a chemical method with 2M TFA at 100 °C and 120 °C and a combined acidic/enzymatic method. After hydrolysis, the contents of galacturonic acid and neutral sugars were measured by HPLC. Complete hydrolysis of polygalacturonic acid occurred after 2.5h incubation with 2M TFA at 120 °C. The efficient hydrolysis of neutral sugars in pectins was performed with 2M TFA at 100 °C for 2.5h. Monomers most susceptible to concentrated acid were rhamnose, mannose and arabinose.

Bound phenolics in foods, a review

Among phytochemicals, phenolic compounds have been extensively researched due to their diverse health benefits. Phenolic compounds occur mostly as soluble conjugates and insoluble forms, covalently bound to sugar moieties or cell wall structural components. Absorption mechanisms for bound phenolic compounds in the gastrointestinal tract greatly depend on the liberation of sugar moieties. Food processes such as fermentation, malting, thermoplastic extrusion or enzymatic, alkaline and acid hydrolyses occasionally assisted with microwave or ultrasound have potential to release phenolics associated to cell walls. Different kinds of wet chemistry methodologies to release and detect bound phenolic have been developed. These include harsh heat treatments, chemical modifications or biocatalysis. New protocols for processing and determining phenolics in food matrices must be devised in order to release bound phenolics and for quality control in the growing functional food industry.