Kinetic Dependences of Two-Stage Dilute Acid and Enzyme Hydrolysis of Paulownia tomentosa

The sugars potential ofPaulownia tomentosa is estimated by dilute acid pretreatment and cellulase hydrolysis. The kinetics of dilute （1%） sulfuric acid hydrolysis is studied at temperatures of 100 ℃, 120 ℃ and 130 ℃, while the kinetics of the subsequent enzyme hydrolysis is examined at a temperature of 50 ℃ and reaction time varied from 60 to 300 min using cellulase complex NS 50013 and β-glucosidase N S 50010. The reducing sugars formation is modeled as a pseudo-homogeneous first order reaction in view of the kinetics of dilute sulfuric acid hydrolysis. The results obtained indicate that the reaction proceeds in an energetically homogeneous system （E = const） providing identical accessibility of the reagent to the hydrolyzing sites （A = const）. The enzyme hydrolysis kinetics follows heterogeneous catalytic mechanism. The process is described by an exponential kinetic equation, which is well recognised in case of processes on uniformly inhomogeneous surfaces. The current rate decreases significantly probably because of exhaustion of the available active sites on the surface and steric hindrances due to the presence of lignin. This investigation provides information of importance for the fermentation step of the bio-ethanol production process.

Food-derived bio-functional peptides for the management of hyperuricemia and associated mechanism

Hyperuricemia,a metabolic disorder related to uric acid metabolism dysregulation,has become a common metabolic disease worldwide,due to changes in lifestyle and dietary structure.In recent years,owing to their high activity and few adverse effects,food-derived active peptides used as functional foods against hyperuricemia have attracted increasing attention.This article aims to focus on the challenge associated with peptide-specific preparation methods development,functional components identification,action mechanism(s)clarification,and bioavailability improvement.The current review proposed recent advances in producing the food-derived peptides with high anti-hyperuricemia activity by protein source screening and matched enzymatic hydrolysis condition adjusting,increased the knowledge about strategies to search antihyperuricemia peptides with definite structure,and emphasized the necessity of combining computer-aided approaches and activity evaluations.In addition,novel action mechanism mediated by gut microbiota was discussed,providing different insights from classical mechanism.Moreover,considering that little attention was paid previously on the structure-activity relationships of anti-hyperuricemia peptides,we collected the sequences from published studies and make a preliminary summary about the structure-activity relationships,which in turn provided guides for enzymatic hydrolysis optimization and bioavailability improvement.Hopefully,this article could promote the development,application and commercialization of food-derived anti-hyperuricemia peptides in the future.

Purification and Characterization of Angiotensin I Converting Enzyme Inhibition Peptides from Sandworm Sipunculus nudus

Three angiotensin I converting enzyme(ACE) inhibition peptides were isolated from sandworm Sipunculus nudus protein hydrolysate prepared using protamex. Consecutive purification methods, including size exclusion chromatography and reverse-phase high performance liquid chromatography(RP-HPLC), were used to isolate the ACE inhibition peptides. The amino acid sequences of the peptides were identified as Ile-Asn-Asp, Val-Glu-Pro-Gly and Leu-Ala-Asp-Glu-Phe. The IC_(50) values of the purified peptides for ACE inhibition activity were 34.72 μmol L^(-1), 20.55 μmol L^(-1) and 22.77 μmol L^(-1), respectively. These results suggested that S. nudus proteins contain specific peptides that can be released by enzymatic hydrolysis. This study may provide an experimental basis for further systematic research, rational development and clinical utilization of sandworm resources.

Extraction of Amino Acids from Excess Activated Sludge by Enzymatic Hydrolysis

A study was undertaken to investigate the production of amino acids from excess activated sludge (EAS) by enzymatic hydrolysis. Firstly, the protein was extracted from EAS. Secondly, the protein solution was further hydrolyzed under free enzyme or immobilized enzyme. The reversed phase high performance liquid chromatography (RP-HPLC) and inductively coupled plasma emission spectrometer (ICP) were applied to determine the contents of amino acids and heavy metals, respectively. The effects of enzyme/substrate(E/S), pH, temperature, and reaction time were investigated in detail. The results indicated that, the optimum conditions for protein hydrolysis were temperature 55℃, pH 10, E/S 9 g/L, and reaction time 8 h, and the highest yield of amino acids was more than 10 g/100 g dry sludge (DS) under free enzyme. Moreover, the security and nutrition were taken into consideration. There were seven kinds of essential amino acids and ten non-essential amino acids in the raw amino acid (RAA) solution, and the contents of heavy metals were lower, living up to Hygienical standard for feeds (China). This technology widens the source of amino acids and makes the extraction of amino acids from EAS more economic and effective.

Enzyme hydrolyzed bael fruit liquefaction and its kinetic study

The study aims to explore the mechanism and optimize the process of enzyme hydrolyzed bael fruit(Aegle marmelos)liquefaction using two different enzymes:pectinase and macerozyme r-10(enzyme mixture).A full factorial design was applied for the factors with 0.05–1.5%(w/w)enzyme concentration(EC),30–60℃ temperature,and incubation time of 30–240 min for pectinase and 60–360 min for macerozyme.Quadratic polynomial models were developed,showing R^(2)≥0.94.Multi-objective numeric optimization was followed to maximize the increase in yield,total reducing sugar(TRS),clarity,and minimizing EC,temperature and time.Enzyme-treated juice extracts were acceptable on the sensory scale with overall acceptability>5.Maximum pomace reduction of 58.8%and 78.9%along with rise in mono and disaccharides were observed after treating with pectinase(t=240 min)and macerozyme(t=360 min),respectively at identical 0.775%EC and 45℃ temperature.With the pectinase enzyme,an optimumΔyield of 32.4%was obtained at 0.82%EC,43℃ temperature in 169.4 min.Subsequently,with the macerozyme,an optimumΔyield of 39.6%was attained at 0.96%EC,45.6°C temperature in 245.9 min.Substrate degradation in bael fruit by enzymatic hydrolysis with pectinase(EC=0.01–1.50%,time=2.5–240 min)and macerozyme(EC:0.01–1.50%,time:5–360 min)was studied at their respective optimum temperatures.The modified Michaelis-Menten showed a good fit(R 2>0.98)with the non-linear curve fitting method.Macerozyme treatment showed slower enzyme activity with higher substrate degradation but lower nutrient content compared to the pectinase treatment.

Effect of heat treatment on amino acids and volatile compounds of enzymatic pork trimmings hydrolysate supplemented with xylose and cysteine

In this research,the effects of heat treatment together with xylose and cysteine addition on the amino acid changes and volatile compound generation in non-enzymatic pork trimmings extract(NPE)or enzymatic pork trimmings hydrolysate(EPH)were studied.Enzymatic hydrolysis significantly increased the total amino acid content and provided necessary precursors for the thermal reactions.The addition of xylose assisted the browning process while the cysteine addition partially inhibited the formation of brown colour in both NPE and EPH.The addition of both cysteine and xylose significantly increased the formation of sulfur-containing volatile flavour compounds in EPH samples,but not in NPE samples.The characteristic“roasted meat”like aromatic volatile compounds,in particular,2-furfurylthiol,were only detected in EPH samples at 8.13 ng/mL,when both xylose(35 mg/mL)and cysteine(10 mg/mL)were added.

Heat-denatured and alcalase-hydrolyzed protein films/coatings containing marjoram essential oil and thyme extract

In this study,heat-denatured and alcalase-hydrolyzed whey and soy protein films/coatings containing marjoram essential oil(MEO)and thyme extract(TE)were investigated comparatively in terms of physicochemical and functional properties.Heat-denaturated high protein solutions produced self-standing,smooth,transparent and viscoelastic films in the presence of glycerol.Enzymatic hydrolysis provided transparency,elasticity and extensibility to the films of low protein solutions.The addition of MEO and TE triggered hardness and brittleness especially in hydrolyzed high protein films and remarkably changed film color,thickness and viscosity possibly affecting surface adherence of films.Heat denatured films exhibited higher water vapor permeability(WVP)than alcalase-hydrolyzed ones.The lowest hardness was obtained in hydrolyzed low protein films with considerable adhesiveness.Hydrolyzed protein solutions coated to cheese provided better protection against moisture loss and MEO added films caused elevated hardening of cheese.MEO and TE incorporated in film matrices were seemed to suppress mycelial growth and sporulation of Aspergillus niger.This study presented valuable new findings on functional protein films produced by enzymatic hydrolysis as an alternative to heat treatment.