Optimum Conditions For Enzymatic Hydrolysis Research Articles

Novel peptides with α-glucosidase inhibitory activity from Changii Radix hydrolysates

The objective of this research was to investigate the α-glucosidase inhibitory activity of peptides released from Changii Radix protein under the optimal enzymatic hydrolysis conditions of trypsin, flavourzyme, compound proteinase, papain, alkaline proteinase, neutral protease, and in vitro simulated human gastrointestinal digestive conditions. The hydrolysate with the best activity was further purified by ultrafiltration, size-exclusion chromatography and semi-preparative high performance liquid chromatography. The peptides in the most active fraction were subsequently identified by nano-LC–MS/MS and screened for bioactivity. As a result, the GID-3-SG-2-RP-2 fraction (with smaller molecular weight and more hydrophobic) manifested the highest effect with an IC50 value of 32 μg/mL. Three peptides of this fraction were synthesized, SQHISTAGMEASGTSNMKF, KVIISAPSKDAPMF, and STFQQMW, and provided an IC50 of 1.051, 0.032, and 1.104 mg/mL, respectively. Thus, the results indicated that Changii Radix derived peptides may have potential functions in the prevention and management of type 2 diabetes.

Production and transepithelial transportation of casein-derived peptides and identification a novel antioxidant peptide LHSMK

In this study, casein derived peptides were hydrolyzed with trypsin and then transported across Caco-2 cell monolayers to choose intestinal absorbable antioxidant peptides. E/S ratio at 5.45 %, pH at 7.13 and temperature at 51.99 °C were found to be the optimal conditions for enzymatic hydrolysis of casein by trypsin by Response Surface Method. The fraction below 10 kDa purified by the hollow fiber ultrafiltration membrane was applied to Sephadex G-10 gel filtration chromatography, and the obtained components were transported across the Caco-2 cell monolayer. The transported peptides were detected on the basolateral side of the Caco-2 cell monolayer using ultra-performance liquid chromatography-tandem mass spectrometry. It was found that LHSMK was an unreported pentapeptide. The synthetic peptide LHSMK had free radical scavenging ability, and the antioxidant activity exhibited a dose-dependent increase. Furthermore, LHSMK can also regulate antioxidant enzymes activity in oxidative-damage cells. This study provides a method for the preparation of intestinal absorbable peptides, and provides basic research for the development of functional food market.

Optimization of enzymatic protein hydrolysis conditions of Asiatic hard clam (Meretrix meretrix)

This study was aimed to optimise the Alcalase® enzymatic hydrolysis extraction of Asiatic hard clam (AHC) (Meretrix meretrix) protein hydrolysate in terms of hydrolysis time, hydrolysis temperature, hydrolysis pH, and concentration of enzyme. Protein hydrolysate produced from AHC (M. meretrix) meat was used to determine the optimum hydrolysis conditions. Hydrolysis of AHC meat was optimised using the Central Composite Design Response Surface Methodology (RSM) (CCD). The relationship between four parameters such as temperature (45 – 65°C), enzyme to substrate concentration (1 – 2%), hydrolysis time (60 – 180 mins), and pH (7.5 – 9.5) to the degree of hydrolysis was investigated. The optimum conditions for enzymatic hydrolysis of AHC meat to achieve the maximum degree of hydrolysis (DH) were observed at 65°C, enzyme to substrate concentration of 1%, hydrolysis time of 60 mins, and pH 7.5. The enzymatic protein hydrolysis of AHC meat was predicted using a two factors interaction (2FI) model. Under these optimum conditions, DH's predicted value was 97.41%, which was close to the experimental value (97.89%). The freeze-dried protein hydrolysate powder was characterized concerning the proximate composition. Proximate analysis revealed that the AHC meat contains 7.92±1.76% of moisture, 2.23±0.89% of crude fat, 1.98±0.82 of ash, and 10.53±0.04% of crude protein. While the Asiatic hard clam protein hydrolysate (AHCPH) composed 9.12±0.02% of moisture, 0.80±0.29% of crude fat, and 27.76±0.10% of ash. The protein hydrolysate produced also contained high protein content (50.09±0.88%) and may serve as a good protein source.

Optimization of Enzymatic Hydrolysis Conditions for the Production of Crisp Plum Juice by Response Surface Methodology

Objective: To investigate the optimum enzymolysis extraction process conditions of plum fruit, and to provide theoretical bases fordeep processing andutilizationof itsresources. Method: The juice yield was used as an indicator. On the basis of single-factor experiments, response surface methodology (RSM) was employed to optimize the enzymatic hydrolysis pretreatment conditions for extracting fruit juice from crisp plum with methods of adding enzymes, including pectinases, cellulase and complex enzyme consisted of pectinases and cellulase. Result: The results suggested that the extraction parameters in the order of significance were enzymolysis temperature, enzyme concentration, enzymolysis pH, and enzymolysis time by response surface analysis. The optimum conditions of enzymolysis with pectinases were pectinases concentration 0.45 g/L, enzymolysis temperature 38 ℃, enzymolysis pH3.8 and enzymolysis time 72 min, in which the average juice yield of crisp plum was 78.63%. The optimum conditions of enzymolysis with cellulase were cellulase concentration 0.55 g/L, enzymolysis temperature 41 ℃, enzymolysis pH4.2 and enzymolysis time 105 min, in which the average juice yield of crisp plum was 74.33%. The optimum conditions of enzymolysis with complex enzyme were pectinases concentration 0.45 g/L, cellulase concentration 0.55 g/L, enzymolysis temperature 41 ℃, enzymolysis pH4.0 and enzymolysis time 87 min, in which the average juice yield of crisp plum was 81.51%. Conclusion: In the extract process of crisp plum juice, juice yields all increased when extracting juice, by adding pectinases, cellulase or complex enzyme consisted of pectinases and cellulose on the corresponding optimal conditions of enzymatic hydrolysis. The study provides technical references for the product development of Guizhou plum fruit.

Statistical Optimization of Alkali Pretreatment to Improve Sugars Recovery from Spent Coffee Grounds and Utilization in Lactic Acid Fermentation

Biorefinery, which utilizes carbon-neutral biomass as a resource, is attracting attention as a significant alternative in a modern society confronted with climate change. In this study, spent coffee grounds (SCGs) were used as the feedstock for lactic acid fermentation. In order to improve sugar conversion, alkali pretreatment was optimized by a statistical method, namely response surface methodology (RSM). The optimum conditions for the alkali pretreatment of SCGs were determined as follows: 75 °C, 3% potassium hydroxide (KOH) and a time of 2.8 h. The optimum conditions for enzymatic hydrolysis of pretreated SCGs were determined as follows: enzyme complex loading of 30-unit cellulase, 15-unit cellobiase and 50-unit mannanase per g biomass and a reaction time of 96 h. SCG hydrolysates were used as the carbon source for Lactobacillus cultivation, and the conversions of lactic acid by L. brevis ATCC 8287 and L. parabuchneri ATCC 49374 were 40.1% and 55.8%, respectively. Finally, the maximum lactic acid production by L. parabuchneri ATCC 49374 was estimated to be 101.2 g based on 1000 g of SCGs through the optimization of alkali pretreatment and enzymatic hydrolysis.

Optimization of Cellulase Immobilization with Sodium Alginate-Polyethylene for Enhancement of Enzymatic Hydrolysis of Microcrystalline Cellulose Using Response Surface Methodology.

A novel method of immobilizing cellulase on sodium alginate (SA)-polyethylene glycol (PEG) enabled the cellulase to be used repeatedly. The matrix of the immobilized cellulase was detected and characterized using Fourier transform infrared spectroscopy and scanning electron microscopy. In comparison with SA-immobilized cellulase, the relative enzyme activity and immobilization rate increased by 25% and 18%, respectively. The application range of the immobilized enzyme in terms of temperature and pH was larger than that of the free enzyme, and its thermal stability increased. The immobilized enzyme was used in enzymatic hydrolysis, in which MCC was used as the substrate. The optimal conditions for enzymatic hydrolysis were as follows: the dosage of SA-PEG-immobilized cellulase was 3.55 g/g total solids of the substrate, the concentration of the substrate was 13.16%, and the pH was 5.11. In comparison with the yield of reducing sugars in the first round of hydrolysis of MCC by SA-immobilized cellulase, the yield in the hydrolysis of MCC by SA-PEG-immobilized cellulase increased by 133%. After five cycles of repeated use, the total yield of reducing sugars when MCC was hydrolyzed by SA-PEG-immobilized cellulase was similar to that achieved with free cellulase. In comparison with the free enzyme, the highest yield when the immobilized enzyme was used was 22.68%. Therefore, the immobilized cellulase exhibited high performance in enzymatic hydrolysis.

Investigation of optimal conditions for production of antioxidant peptides from duck blood plasma: response surface methodology

Duck blood is rich in protein. It is one of the main by-products in the slaughter industry. The objective of this research was to optimize and establish a method for producing duck plasma antioxidant peptides. The composition of duck plasma powder was analyzed. Protease selection experiment (Alcalase, Protamex, and Flavourzyme) and single-factor experiment were performed, and response surface methodology was used to determine the optimal hydrolysis conditions for duck plasma. Among the proteases, Alcalase hydrolysate exhibited the strongest 1,1-diphenyl-2-picrylhydrazyl scavenging rate. The optimum enzymatic hydrolysis conditions were hydrolysis time of 6 h, temperature of 65.5°C, pH 10.0, and enzyme-to-substrate ratio of 0.3%. The 1,1-diphenyl-2-picrylhydrazyl scavenging rate reached 64.84%, and the ratio of essential amino acids was 38.76%. Briefly, the duck plasma hydrolysate exhibited strong antioxidant properties and reasonable composition of amino acids. Thus, it may be used as a nutritional or functional ingredient in foods or medicines. This research provides a theoretical basis for comprehensive processing and high value utilization of duck plasma.

Preparation and purification of an immunoregulatory peptide from Stolephorus chinensis of the East Sea of China

Immunomodulatory peptides derived from marine organisms are potential sources of new immunomodulating drugs. This study aimed to investigate the optimal enzymatic hydrolysis conditions of immunoregulatory peptides from Stolephorus chinensis. The relative proliferation rate (RPR) of RAW264.7 macrophages was set as the screening index. The immunoregulatory peptides from S. chinensis was prepared via process optimization, ultrafiltration, ion-exchange chromatography, and reverse-phase high-performance liquid chromatography (RP-HLPC). The amino acid sequence of the immunoregulatory peptide from S. chinensis (IPSC) was identified to be Tyr-Val-Met-Arg-Phe (YVMRF; MW 715.4 Da) using Edman degradation and mass spectrometry. In addition, the macrophages became larger with more pseudopods after IPSC treatment, indictating that IPSC stimulated RAW 264.7 differentiation. IPSC also increased productions of nitric oxide (NO), interleukin-6 (IL-6), interleukin-1β (IL-1β), and tumor necrosis factor-α (TNF-α). Our results provide a theoretical basis for preparing immunomodulatory functional food from S. chinensis in future.

Study on optimization of extraction process and resistance to oxidation of Polypeptide from sea cucumber waste liquid

The protease hydrolysis technology is used to extract the polypeptides from the sea cucumber waste liquid. The enzymatic hydrolysis ability of protein in sea cucumber waste liquid by seven proteases shows that the best protease is compound protease by taking the hydrolysis degree as the index. Furthermore, the effects of enzyme dosage, pH, temperature and time of enzymatic hydrolysis on the hydrolysis degree are studied, and Box-Benhnken central composite test and response surface analysis method are used to optimize the enzymatic hydrolysis conditions.. The results show that the optimal enzymatic hydrolysis conditions are: enzyme dosage: 647 U/g; pH: 6.48; temperature: 52.5°C; enzymatic hydrolysis time: 3.44h; protein hydrolysis degree under the best condition: 25.9%. The polypeptides extracted from the sea cucumber waste liquid have high antioxidant activity, and the DPPH· scavenging activity increases with the polypeptide concentration.

Optimising enzymatic conditions of monkfish (Lophius vomerinus) heads hydrolysis towards potential waste biomass valorisation

Enzymatic protein hydrolysis of fish processing by-products offers an alternative option to valorise this raw material. Monkfish heads originating from fish processors presents such an opportunity, as the heads constitute a significant portion of the total fish (approximately 30%) and are currently processed into relatively low-value fish meal or even discarded. In this study, the reaction conditions for enzymatic protein hydrolysis of monkfish heads were optimised by varying the reaction pH and temperature using the Alcalase proteolytic enzyme. A mixed 2-factor, 3-level factorial design was employed to determine significant factors and interactions and was followed by response surface optimisation to determine optimal enzymatic hydrolysis conditions, which were shown to occur at 62 °C and a pH of 8.2. In addition, proximate analysis of the raw material and functional property characterisation of both the aqueous fish protein hydrolysate (FPH) phase and the insoluble sediments were performed to maximise the possibility of total raw material utilisation. Both the FPH and sediment displayed functional and bioactive properties, including emulsion stabilisation, fat absorption and antioxidant activity; only the FPH displayed foaming capacity, while the sediment displayed a reasonable emulsion activity index. In addition, high levels of essential amino acids (EAA) were found in the sediment (49.5% of the total amino acids), and all EAA were present (except tryptophan, which was not analysed for), which confirmed the high quality of the protein contained in the sediment. Overall, this work successfully optimised hydrolysis conditions for the Alcalase/monkfish system and confirmed the potential of enzymatic protein hydrolysis as an upgrading strategy to better utilise monkfish processing by-products.

Optimization of Enzymatic Hydrolysis Process of Antarctic Krill and Cryoprotective Effect of Enzymatic Hydrolysates on Oyster Meat

In order to develop a safe and efficient non-phosphorus antifreeze agent,enzymatic hydrolysates of Antarctic krill were prepared to evaluate their cryoprotective effects,providing basic data for the development of new antifreeze agents.The alkaline protease was screened from the four proteases as experimental enzymes,and the enzymatic hydrolysis process was optimized by single factor experiment and orthogonal experiment. The freezing protection of oyster meat by enzymatic hydrolysates of Antarctic krill was studied with the indexes of the water loss rate,salt-soluble protein content,total sulfhydryl group content and Ca2+-ATPase activity.The results showed that the optimum conditions for enzymatic hydrolysis of Antarctic krill by alkaline protease were as follows:Temperature 55℃,pH8.5,enzyme dosage 2.6%,enzymatic hydrolysis time 5 h. Under these conditions,the relative molecular weight of enzymatic hydrolysates of Antarctic krill mainly distributed in the range of 100~5500 Da,accounting for 79.69% of the total enzymatic hydrolysates. The enzymatic hydrolysate of Antarctic krill could inhibit the loss of water after freezing storage,retard the decrease of salt-soluble protein content,Ca2+-ATPase activity and total sulfhydryl content,and its effect was better than that of phosphorus-containing antifreeze agent.Therefore,the enzymatic hydrolysate of Antarctic krill had freezing protection activity,which could be further separated and identified.

Enhancement on enzymolysis of pigskin with ultrasonic assistance

ABSTRACT The fur is hard to decompose during the fermentation process of diseased swine carcasses. In order to enhance the enzymolysis of pigskin, the ultrasonic was proposed to use during the process of the enzymatic hydrolysis. The response surface optimization experiments were carried out with the DH (degree of hydrolysis) as the response value and the optimum conditions for enzymatic hydrolysis were determined. Based the optimum conditions, orthogonal experiments were carried out with ultrasonic frequency, power and time as variables, and optimal ultrasonic parameters were obtained. Without the assistance of ultrasonic, the descending order of influence factors on DH was, temperature＞SC(Substrate concentration)＞RES(The ratio of enzyme to substrate)＞pH. Moreover, the DH value is of 10.42% under the following optimal conditions: RES is of 16,006 U/g, the temperature is of 48.92°C, the SC is of 59.76 g/L and pH is of 10.43. Frequency has the greatest effect on DH, followed by power, and finally time. The optimum hydrolysis time is of 5 h, and the DH is of 22.94% were obtained under the following optimum ultrasonic pretreatment conditions: frequency combination is of (20,40,40), power is of 600 W and time is of 25 min. Comparing with the group without ultrasonic pretreatment, the DH for the ultrasonic assistance increased by 4%, the hydrolysis time was shorten by 3 h, and the total amino acids increased by 15.98%.

Production of microbial lipids from optimized waste office paper hydrolysate, lipid profiling and prediction of biodiesel properties

Waste office paper (WOP), was used to produce microbial lipids using Cryptococcus curvatus. Pretreatment of WOP with 1% (v/v) sulfuric acid removed the lignin without any inhibitor formation and increased the cellulose content. The optimum conditions for enzymatic hydrolysis of WOP were predicted at 92 h, 50 FPU/g cellulase, 50 CBU/g β-glucosidase, 5% substrate loading, 50 mL working volume and 156 rpm using the central composite design. The maximum sugar yield obtained in the validation experiment was 35.3 g/L. Ammonium chloride and yeast extract combination were more suitable for lipid production by C. curvatus with the carbon to nitrogen ratio of 60. A maximum biomass 11.48 ± 0.09 g/L was obtained at 120 h with a lipid yield of 4.95 ± 0.02 g/L. The lipid profile studies reveal the presence of 11 fatty acid methyl esters. These predominantly comprised of (%, w/w) 50.8% oleic acid, 25.7% palmitoleic acid, 7.1% stearic acid, and 6.5% myristic acid. The characteristic features of the biodiesel, such as cetane number, cold performance, density and iodine value met the requirements of the international standard (EN14214). Thus, the WOP could be a potential renewable feedstock to produce microbial lipids which are essential for the future sustainable production of biodiesel.

Optimization of Enzymatic Hydrolysis Conditions of Caspian kutum (Rutilus frisii kutum)ˮ By-product for Production of Bioactive Peptides with Antioxidative Properties

The enzymatic hydrolysis was performed by Alcalase to recover the fish protein hydrolysate from Caspian kutum by-product (CB). The degree of hydrolysis (DH) was applied for monitoring the hydrolysis reaction of CB. The response surface methodology was applied based on a D-optimal design to perform the optimization process for obtaining the high yield of CB protein hydrolysate. The effect of four independent variables including pH (7.5–8.5), temperature (45–55 °C), time (1–3 h), and enzyme concentration (0.5–1.5% w/w) on DH was studied. The results indicated that the predicted and actual values of the optimum condition had no significant difference. The optimum enzymatic hydrolysis conditions were achieved at pH 8.5, temperature of 55 °C, enzyme concentration of 1.5% w/w, and time of 3 h, which resulted in the maximum value of DH (19.08%). Antioxidant assays including DPPH scavenging and metal chelating activities showed that Caspian kutum protein hydrolysates had antioxidant properties.

Thermal-alkali and enzymes for efficient biomethane production from co-digestion of corn straw and cattle manure

This research evaluated a sequential process of thermal-alkali pretreatment, enzymatic hydrolysis, and anaerobic co-digestion applied on a mixture of corn straw (CS) and cattle manure (CM). The results showed that the optimal conditions of thermo-alkaline pretreatment were a Ca(OH)2 dosage of 1.5% and temperature of 120 °C. The optimal conditions of enzymatic hydrolysis in terms of cellulase loading, operational time, and protease loading were determined. Co-digestion with enzymes and thermal-alkali pretreatment achieved the highest methane yield of 0.41 m3 kg-1-VS from the liquid of hydrolysates. An maximum applicable organic loading rate (OLR) of 13.7 kg-SCOD m-3 d-1 was found with a soluble chemical oxygen demand (SCOD) removal of 96.4% in an expanded granular sludge blanket (EGSB) reactor. The optimization of conditions could lead to the industrial-scale treatment of organic solids with a high energy yield and efficiency.

Nutritional compositions of Indian Moringa oleifera seed and antioxidant activity of its polypeptides.

To study the nutritional composition of Indian Moringa oleifera seed and the antioxidant activity of M. oleifera seed polypeptide, Indian M. oleifera seed was used as raw material for composition analysis and content determination. After extraction of the seed protein, enzymatic hydrolysis with flavourzyme, dispase, papain, pepsin, and alcalase was conducted for different time, and the optimal enzymatic hydrolysis conditions was determined with DPPH scavenging capacity as an indicator. The seed polypeptides obtained by enzymatic hydrolysis were ultrafiltered, and the active peptide fragments were tracked with DPPH, HO (•OH), ABTS and superoxide anion (O2•−) free radical scavenging ability and lipid oxidation inhibition rate as indicators. The results showed that the protein content in Indian M. oleifera seed was high to 40.34%, containing seven essential amino acids. The content of macroelements such as potassium, sodium, and magnesium is high, with the potassium content as high as 2,357.71 mg/kg, among the microelements, the iron content as high as 36.2 mg/kg. The optimum enzymatic hydrolysis conditions were as follows: enzymatic hydrolysis with flavourzyme (50°C, pH 6.7) for 300 min, and DPPH scavenging capacity was 84.76%. Activity tracing found that the polypeptide fragment with molecular weight <3.5 kDa had the strongest antioxidant capacity, and the EC50 values of DPPH, •OH, ABTS, and O2•− free radical scavenging rates were 4.0, 4.2, 5.3, and 4.3 mg/ml, respectively. The above results show that Indian M. oleifera seed not only has high nutritional value, but its protease enzymatic hydrolyzate also has significant antioxidant activity, which can be further developed into nutrition products, healthcare products, functional foods, beauty and skin care products, liver protection drugs, etc.

Discussion on the Analysis of Biomass Energy Utilization

In order to solve the problem of energy shortage and environmental pollution, eucalyptus is used as raw material to optimize the best process through dilute acid pre-treatment, enzymatic hydrolysis and fermentation, with xylose recovery rate, cellulose enzymatic hydrolysis rate, and total sugar yield as evaluation indicators. It has guiding significance for renewable biomass energy tree species to replace non-renewable petroleum-based raw materials to produce biobutanol, and the future development direction of biomass energy tree species production is looked forward. The pre-treatment process of eucalyptus with dilute sulfuric acid is optimized by response surface methodology. The effects of sulfuric acid concentration, solid-liquid ratio, reaction time and temperature on the pre-treatment effect are investigated with xylose recovery, cellulose enzymatic hydrolysis and total sugar yield as indicators. The results show that the pre-treatment effect of eucalyptus is the best when the concentration of H2SO4 is 0.52%(w/w), the pre-treatment temperature is 168 °C, and the time is 27min, and at this time, the xylose recovery rate is 87.58%. Then, under the optimum pre-treatment conditions, the effects of enzyme dosage and time on enzymatic hydrolysis are studied. The optimum enzymatic hydrolysis conditions are as follows: cellulase dosage 60FPU/g dry matter, and enzymatic hydrolysis for 36h. The cellulase hydrolysis rate can reach 90.82%, and the total sugar yield is 95.16%.

PRODUCTION OF MALTOOLIGOSACCHARIDES FROM HUTAN JATI VARIETY CULTIVAR TACCA (Tacca leontopetaloides) STARCH

This research aimed to extract and characterize the physicochemical properties of starch from Tacca tuber, to determine the optimum conditions for enzymatic hydrolysis to produce maltooligosaccharides, and to analyze the character of these maltooligosaccharides. The analysis was conducted by calculating the amount of reducing sugar, total sugar, and the degree of polymerization, and by using the TLC (Thin Layer Chromatography) and HPLC (High-Performance Liquid Chromatography) analyses. The Hutan Jati variety cultivar of Tacca was selected from three Tacca variety cultivars (Hutan Jati, Pulau Katang and Gunung Batur) to produce maltooligosaccharides by enzymatic hydrolysis of crude Brevibacterium sp. α-amylase. The optimum conditions for the enzymatic hydrolysis of Hutan Jati variety cultivar Tacca starch for the production of maltooligosaccharides were obtained at a substrate concentration of 3% (w/v) and a ratio of 1:5 enzyme and substrate at 6 hours incubation time. From 250 mL of fresh hydrolysate, some 34.49 grams of powder maltooligosaccharide were produced. The TLC and HPLC results showed a similar yield of both the liquid and powder maltooligosaccharides with maltose, maltotriose, and maltotetraose as the main products. Considering its physicochemical characteristics and the product of its maltooligosaccharides, the starch from the tuber of Hutan Jati variety cultivar Tacca possessed strong potential for the future production of maltooligosaccharides particularly,  maltotriose and maltotetraose, in food industries.

Optimization of the ultrasonic-microwave assisted enzymatic hydrolysis of freshwater mussel meat

In the present study, the Ultrasonic-Microwave (US-MW) technique was applied for assisting enzymatic hydrolysis of freshwater mussel meat. The operating parameters of enzymatic hydrolysis were investigated and the properties and qualities of the freshwater mussel hydrolysates were also analyzed. The considerable optimum conditions for enzymatic hydrolysis of mussel meat were ratio of liquid to material of 10.36:1, power of 360.52 W, processing time of 6.91 min, enzymolysis time of 4 h. Under these conditions, a degree of hydrolysis (DH) of 48.40% was obtained. The hydrolysates produced under optimum conditions, were characterized in terms of electrophoretic profile, amino acid composition and infrared spectrum analysis. SDS-PAGE profiles of the hydrolysates revealed that several protein bands were cleaved and several light myosin chains (25 kDa and 15 kDa, respectively) and peptides of molecular weight lower than 6.5 kDa were identified. The infrared spectrum absorption peak of amide band A and band III shifted after US-MW pre-treatment, which indicated that the N-H (hydrogen bonding) stretching vibration and triple helix structure of samples were affected. The essential amino acids in hydrolysates with or without US-MW pre-treatment were 36.62 mg/100 g and 33.40 mg/100 g. It was proved that US-MW assisted enzymatic hydrolysis is an effective technology to utilize freshwater mussel meat. Keywords: ultrasonic-microwave (US-MW), freshwater mussel meat, enzymatic hydrolysis, degree of hydrolysis (DH) DOI: 10.25165/j.ijabe.20181105.4104 Citation: Zhou Y J, Yi X L, Wang J Y, Yang Q, Wang S J. Optimization of the ultrasonic-microwave assisted enzymatic hydrolysis of freshwater mussel meat. Int J Agric & Biol Eng, 2018; 11(5): 236–242.

Improving enzymatic digestibility of wheat straw pretreated by a cellulase-free xylanase-secreting Pseudomonas boreopolis G22 with simultaneous production of bioflocculants

BackgroundXylan removal by bacterial pretreatments has been confirmed to increase the digestibility of biomass. Here, an effective xylan removal technique has been developed to enhance the digestibility of wheat straw and simultaneously produce bioflocculants by a cellulase-free xylanase-secreting strain, Pseudomonas boreopolis G22.ResultsThe results indicated that P. boreopolis G22 is an alkaliphilic strain which can secrete abundant amounts of xylanase. This xylanase had activity levels of 2.67–1.75 U mL−1 after an incubation period of 5–25 days. The xylanase showed peak activity levels at pH 8.6, and retained more than 85% relative activity in the pH range of 7.2–9.8. After 15 days of cultivation, the hemicellulose contents of the wheat straw were significantly decreased by 32.5%, while its cellulose contents were increased by 27.3%, compared to that of the control. The maximum reducing sugars released from the 15-day-pretreated wheat straw were 1.8-fold higher than that of the untreated wheat straw, under optimal enzymatic hydrolysis conditions. In addition, a maximum bioflocculant yield of 2.08 g L−1 was extracted from the fermentation broth after 15 days of incubation. The aforementioned bioflocculants could be used to efficiently decolorize a dye solution.ConclusionsThe results indicate that the cellulase-free xylanase-secreting P. boreopolis G22 may be a potential strain for wheat straw pretreatments. The strain G22 does not only enhance the enzymatic digestibility of wheat straw, but also simultaneously produces a number of bioflocculants that can be used for various industrial applications.