Enzymatic Hydrolysis Method Research Articles

Enhanced physicochemical characteristics and biological activities of low-temperature ethylenediamine/urea pretreated lignin.

Low-temperature ethylenediamine (EDA)/urea pretreatment had been demonstrated to be an efficient pretreatment method for enzymatic hydrolysis and bioethanol production. For high-value utilization of the third main components of lignocellulosic biomass, the physicochemical structure characteristics and biological activities of low-temperature EDA/urea pretreated lignin (EUL) were comprehensively investigated in the present study. The results demonstrated that the pretreatment process facilitated the depolymerization of lignin, resulting in notable reduction in molecular weight and polydispersity index from 2.32 to 1.42kg/mol and 1.44 to 1.20, respectively. The EDA/urea pretreated lignin (EUL) exhibited enhanced ultraviolet absorption capacity and the most significant DPPH radical scavenging and inhibition of Staphylococcus aureus in comparison to the primary lignin (PL) and the NaOH pretreated lignin (NL). Enhanced physicochemical characteristics and biological activities of EUL make it more suitable to be developed as sunscreen ingredient or antioxidant and antimicrobial agent in food preservation and conservation.

Collagen (peptide) extracted from sturgeon swim bladder: Physicochemical characterization and protective effects on cyclophosphamide-induced premature ovarian failure in mice

Premature ovarian failure (POF) is a common female reproductive disorder, with oxidative damage playing a significant role in its development. Studies had demonstrated the beneficial antioxidant, anti-aging, and other biological properties of swim bladder collagen (peptide). In this study, acid extraction, water extraction, and enzymatic hydrolysis methods were used to extract collagen (peptide) from sturgeon (Acipenser sinensis) swim bladder, all of which exhibited significant antioxidant activity. Moreover, the effects observed in POF mice were enhanced, including an increasing in the number of growing ovarian follicles, regulation of serum hormone levels, and alterations in signaling pathways, as evidenced by the up-regulation of Phosphatidylinositol 3-kinase/Protein Kinase B (PI3K/Akt) and B cell lymphoma-2/ Bcl-associated x protein (Bcl-2/Bax) pathways, alongside the down-regulation of the mitogen-activated protein kinases (MAPK) signaling pathway. Sturgeon swim bladder collagen (peptide) could protect against cyclophosphamide-induced POF in mice, which could be very beneficial in the future advancement of health products.

Antioxidant peptides from silver carp steak by alkaline protease and flavor enzyme hydrolysis: Characterization of their structure and cytoprotective effects against H2O2-induced oxidative stress.

Silver carp steak is a rarely utilized silver carp processing byproduct. This study aimed to optimize a dual enzymatic method to extract antioxidant peptide components from silver carp steak and characterize their structure and in vitro antioxidant activity through ultrafiltration purification, response surface methodology, molecular docking, and radical scavenging activity analysis. The optimal extraction conditions for silver carp steak antioxidant peptides (SCSAP) were determined as 1:6 solid-liquid ratio, 1500 U/g alkaline protease addition, 4 h alkaline protease hydrolysis time, 1946 U/g flavor enzyme addition, and 2.5 h flavor enzyme hydrolysis time. The <3 kDa SCSAP component (SCSAP-3kDa) showed the strongest antioxidant activity, with its 1,1-diphenyl-2-trinitrophenyl hydrazine (DPPH) radical scavenging rate, ABTS radical scavenging rate, hydroxyl radical scavenging rate, metal ion chelating rate, and reducing capacity reaching 88.75%, 91.21%, 67.02%, 69.07%, and 0.985, respectively. Moreover, the three peptides (PF-7, GP-8, and YF-10) of 100 µg/mL could protect HepG2 cells from oxidative stress damage by reducing the oxidative damage level and activating Keap1-Nrf2-ARE pathways, enabling an increase of superoxide dismutases (SOD) activity, and a decrease of malondialdehyde (MDA) content and reactive oxygen species (ROS) level. The integrated results indicate the enormous potential of SCSAP-3kDa as a functional food ingredient in the food industry. PRACTICAL APPLICATION: This study selected the antioxidant capacity of silver carp steak peptides as the index and developed a facile dual enzymatic hydrolysis method to obtain three antioxidant peptides (PF-7, GP-8, and YF-10) with biological activity, providing a theoretical basis for bioavailability of antioxidant peptides from silver carp steak and contributing to their application in new functional foods.

Optimization of Polysaccharide Extraction from Polygonatum cyrtonema Hua by Freeze–Thaw Method Using Response Surface Methodology

Polygonatum cyrtonema polysaccharides have a variety of pharmacological effects. The commonly used extraction methods include traditional hot water extraction, alkaline extraction, enzymatic hydrolysis method, ultrasonic-assisted extraction, etc., but there are problems such as low yield, high temperature, high cost, strict extraction conditions, and insufficient environmental protection. In this study, crude polysaccharide extraction from the Polygonatum cyrtonema Hua was performed using the freeze–thaw method. Response surface methodology (RSM), based on a three-level, three-variable Box–Behnken design (BBD), was employed to obtain the best possible combination of water-to-raw material ratio (A: 30–50), freezing time (B: 2–10 h), and thawing temperature (C: 40–60 °C) for maximum polysaccharide extraction. Using the multiple regression analysis and analysis of variance (ANOVA), the experimental data were fitted to a second-order polynomial equation and were used to generate the mathematical model of optimization experiments. The optimum extraction conditions were as follows: a water-to-raw material ratio of 36.95:1, a freezing time of 4.8 h, and a thawing temperature of 55.99 °C. Under the optimal extraction conditions, the extraction rate of Polygonatum cyrtonema Hua polysaccharide (PCP) was 65.76 ± 0.32%, which is well in close agreement with the value predicted by the model, 65.92%. In addition, PCP has significant antioxidant activity. This result shows that the freeze–thaw method can improve the extraction efficiency, maintain the structural integrity of polysaccharides, simplify the extraction process, promote the dispersion of polysaccharides, and is suitable for large-scale industrial production.

Utilization of cotton stalk waste for sustainable isopropanol production via hydrolysis and coculture fermentation

The present investigation focused on isopropanol production from lignocellulosic cotton stalk biomass (CSB) using conventional pretreatment, enzymatic hydrolysis and fermentation methods. In comparison to alkaline (NaOH) pretreatment, dilute sulphuric acid (H2SO4) pretreatment showed higher cellulose exposure (448.5 mg/g). Further, ultrasono assisted acid and alkali pretreatment was performed for maximum exposure of cellulose and it was found 616.9 and 586.15 mg/g respectively. Chemical pretreated CSB was additionally exposed to independent enzymatic hydrolysis using commercial enzymes (Celluclast and Viscozymes) following Response Surface Methodology (RSM), which revealed a maximal production of glucose and xylose yield (544.6 mg/g and 41.8 mg/g). Pretreated and enzymatic hydrolyzed cotton stalk biomass at various conditions were analysed using SEM, FTIR, and XRD to determine the structural and functional changes. Further, a co-culture strategy was employed on pretreated and hydrolyzed CSB using two fermented yeast strains (Saccharomyces cerevisiae and Pichia pastoris) for isopropanol production. HR-MS analysis revealed that the maximum concentration of isopropanol (126.228 mM) was produced in 2:1 proportionate ratio of two fermented yeasts with 20 g/L of substrate loadings at 72 h of incubation time. These results indicate that the production of isopropanol (7.46 g/L) from CSB with different parametric conditions is an encouraging step and can be exploited further for various industrial applications.

Enzymatic hydrolysis method for development of low glycemic index rice flour from temperate grown rice (var. Jehlum): Numerical optimization, rheological and spectroscopic characteristics

This study aimed at optimizing process protocols for development of low glycemic index (GI) rice flour (LGIRF) by employing enzymatic hydrolysis method using central composite rotatable design (CCRD). LGIRF was evaluated for pasting, farinographic, spectroscopic and microbiological attributes. Independent variables for optimization included concentrations of α-amylase (0.02–0.12 %), glucoamylase (0.02–0.24 %), as well as the incubation temperature (55–80°C). Resistant starch (RS), glycemic index (GI) and glycemic load (GL) were investigated as response variables. The optimum conditions for development of LGIRF with better quality were- α-amylase concentration of 0.040 %, glucoamylase concentration of 0.070 % and an incubation temperature of 60 °C. The results of mineral analysis revealed significantly (p < 0.05) lower levels of boron, potassium, zinc, phosphorus, magnesium, and manganese in LGIRF, while iron and copper were significantly higher. The viscosity profile as evident from pasting profile and farinographic characteristics of LGIRF were significantly (p < 0.05) lower than native rice flour. 1H NMR and 13C NMR spectroscopic studies showed an increase in flexible starch segments and a decrease in amorphous portion of starch LGIRF, along with chemical shift alterations in carbons 1 and 4. Free fatty acids and total plate count were significantly (p < 0.05) higher in LGIRF although was within limits.

Bioethanol production from coconut husk using DES-NADES pretreatment and enzymatic hydrolysis method

Bioethanol is an alternative fuel produced during biomass fermentation. Among the available biomass resources for bioethanol production, coconut husk is an interesting raw material due to its high cellulose content. This study aims to evaluate the coconut husk conversion into bioethanol using DES (ChCl:MEA) and NADES (Be:La) solvents for the delignification process. The molar ratios of HBA and HBD of the two solvents were varied (1:4, 1:6, 1:8) at 2, 4, 6, and 8 h for each ratio. The delignified samples were hydrolyzed using the 5% (w/w) of cellulase enzymes and fermented for seven days using Saccharomyces cerevisiae. The results showed that DES (ChCl:MEA) and NADES (Be:La) could remove lignin at about 60.53% and 65.81%. The glucose content was obtained at 0.5% (brix) by both solvents and bioethanol content was obtained at 13.9% and 14% (v/v) for DES and NADES, respectively.

Enhancement of Calcium Chelating Activity in Peptides from Sea Cucumber Ovum through Phosphorylation Modification.

Recently, phosphorylation has been applied to peptides to enhance their physiological activity, taking advantage of its modification benefits and the extensive study of functional peptides. In this study, water-soluble peptides (WSPs) of sea cucumber ovum were phosphorylated in order to improve the latter's calcium binding capacity and calcium absorption. Enzymatic hydrolysis methods were screened via ultraviolet-visible absorption spectroscopy (UV-Vis), the fluorescence spectrum, and calcium chelating ability. Phosphorylated water-soluble peptides (P-WSPs) were characterized via high-performance liquid chromatography, the circular dichroism spectrum, Fourier transform infrared spectroscopy (FTIR), UV-Vis spectroscopy, surface hydrophobicity, and fluorescence spectroscopy. The phosphorus content, calcium chelation rate and absorption rate were investigated. The results demonstrated that phosphorylation enhanced the calcium chelating capacity of WSPs, with the highest capacity reaching 0.96 mmol/L. Phosphate ions caused esterification events, and the carboxyl, amino, and phosphate groups of WSPs and P-WSPs interacted with calcium ions to form these bonds. Calcium-chelated phosphorylated water-soluble peptides (P-WSPs-Ca) demonstrated outstanding stability (calcium retention rates > 80%) in gastrointestinal processes. Our study indicates that these chelates have significant potential to develop into calcium supplements with superior efficacy, bioactivity, and stability.

PEMANFAATAN TERATAI PUTIH SEBAGAI BAHAN BAKU PEMBUATAN SELULOSA MIKROKRISTALIN MENGGUNAKAN HIDROLISIS ENZIMATIK DARI RAYAP Coptotermes sp.

Microcrystalline cellulose is still imported by the Pharmaceutical Industry in Indonesia even though Indonesia has large natural resources but they have not been utilized optimally. Microcrystalline cellulose can be obtained from residue (extraction dregs) in the lotus plant extraction process, namely in the form of simplicia powder which will not be used again (organic solid waste). This research aims to obtain microcrystalline cellulose from several parts of the white lotus plant (Nymphaea nouchali Burm. F.) using the enzymatic hydrolysis method using cellulase from the termite Coptotermes sp., then the quality of the powder will be tested and compared with Avicel PH 101. Each part The white lotus is extracted, then the residue is delignified to obtain α-cellulose, then hydrolyzed with crude extract from Coptotermes sp termite cellulase. so that microcrystalline cellulose is obtained which will then be characterized and compared with the commercial version, namely Avicel® PH 101. The highest yield of microcrystalline cellulose is found in leaves with a yield of 95.3%, followed by leaf stalks 89.3%, flower stalks 75.7%, and the yield lowest in interest with a percentage of 74%. The physical characteristics in the form of color reaction, organoleptics, solubility and pH of white lotus microcrystalline cellulose powder show similarities with the comparison standard. It can be concluded that microcrystalline cellulose powder from several parts of the white lotus plant can be an alternative in obtaining cellulose raw materials from natural sources.

Discovery of Potent Glycosidases Enables Quantification of Smoke-Derived Phenolic Glycosides through Enzymatic Hydrolysis.

When grapes are exposed to wildfire smoke, certain smoke-related volatile phenols (VPs) can be absorbed into the fruit, where they can be then converted into volatile-phenol (VP) glycosides through glycosylation. These volatile-phenol glycosides can be particularly problematic from a winemaking standpoint as they can be hydrolyzed, releasing volatile phenols, which can contribute to smoke-related off-flavors. Current methods for quantitating these volatile-phenol glycosides present several challenges, including the requirement of expensive capital equipment, limited accuracy due to the molecular complexity of the glycosides, and the utilization of harsh reagents. To address these challenges, we proposed an enzymatic hydrolysis method enabled by a tailored enzyme cocktail of novel glycosidases discovered through genome mining, and the generated VPs from VP glycosides can be quantitated by gas chromatography-mass spectrometry (GC-MS). The enzyme cocktails displayed high activities and a broad substrate scope when using commercially available VP glycosides as the substrates for testing. When evaluated in an industrially relevant matrix of Cabernet Sauvignon wine and grapes, this enzymatic cocktail consistently achieved a comparable efficacy of acid hydrolysis. The proposed method offers a simple, safe, and affordable option for smoke taint analysis.

Development of a novel dual-enzyme modification method for the functionality improvement of egg yolk powder

Spray dried egg yolk powder (EYP) is a kind of food ingredient with high nutritional value. However, its low solubility and insufficient emulsifying properties restrict its applications in the food industry. In this study, a new method of dual enzymatic hydrolysis (phospholipase and protease) was proposed to improve the functional properties of EYP including emulsifying properties, solubility, rehydration time and so on. The optimal conditions were determined to be 50 U/g (phospholipase A1 (PLA1)) and 250 U/g (neutral protease). Under these optimal conditions, the solubility of HYP (hydrolyzed EYP) treated by dual enzyme (61.30%) was significantly higher than that of unhydrolyzed EYP (16.49%) or HYP treated by single PLA1 (23.97%). Meanwhile, the emulsifying stability index (ESI) of HYP (hydrolyzed EYP) treated by dual enzymes was about 16/1.4 times larger than unmodified EYP/single PLA1 modified HYP. The increasing electronegativity and decreasing surface hydrophobicity/surface tension of HYP could be responsible for the above results. Scanning electron microscopy (SEM) revealed that dual-enzyme hydrolysis could promote the formation of fine HYP with pore structure, enabling it to rehydrate more effectively. In addition, the usage of protease could improve the radical scavenging activity of dual enzyme modified HYP by releasing antioxidant peptides. This study could provide new insights to promote the techno-functionality of EYP, thus optimizing its utilization as a high-performance emulsifier in the food industry.

Preparation and identification of antioxidant peptides from Quasipaa spinosa skin through two-step enzymatic hydrolysis and molecular simulation

Frog skin, a by-product of Quasipaa Spinosa farming, is rich in protein and potentially a valuable raw material for obtaining antioxidant peptides. This study used papain combined with acid protease to digest frog skin in a two-step enzymatic hydrolysis method. Based on a single factor and response surface experiments, experimental conditions were optimized, and the degree of hydrolysis was 30 %. A frog skin hydrolysate (QSPH-Ⅰ-3) was obtained following ultrafiltration and gel filtration chromatography. IC50 for DPPH, ABTS, and hydroxyl radical scavenging capacities were 1.68 ± 0.05, 1.20 ± 0.14 and 1.55 ± 0.11 mg/mL, respectively. Peptide sequences (17) were analyzed and, through molecular docking, peptides with low binding energies for KEAP1 were identified, which might affect the NRF2-KEAP1 pathway. These findings suggest protein hydrolysates and antioxidant peptide derivatives might be used in functional foods.

Preparation and flocculation performance of a cationic starch based flocculant

Abstract To increase the specific surface area of corn starch and remove the anion contaminant in water, STP-OGG-DD, which is composed of porous corn starch (Stp), methylpropenoxyethyl trimethyl ammonium chloride (DMC) and dimethyldiallyl ammonium chloride (DMDAAC), was prepared and used for the flocculation of humic acid (HA). In this preparation, ferrous sulfate and hydrogen peroxide act as initiators for free radicals that attract cationic monomers to gather on starch chains. The effects of reaction time, reaction temperature, dosage of cationic monomer, and initiator on the reaction performance were investigated. The results showed that the conversion rate of starch monomer was 97.69 %, the grafting rate was 96.47 %, and the grafting efficiency was 95.85 %. Stp-OG-DD was characterized by scanning electron microscopy, and its structure was characterized by X-ray diffraction and infrared spectroscopy. In the flocculation test. The flocculation effect of 30 mg/L flocculants with different grafting rates on 30 mg/L humic acid was investigated, and the relationship between the two was studied. The results showed that the flocculant with a high starch grafting rate had a better removal effect on humic acid and was positively correlated. Different from the traditional gelatinization method, the enzymatic hydrolysis method is used to pretreat starch, which not only saves energy but also enlarges the specific surface area of molecules. In addition, adding two cationic monomers improved the grafting effect of starch. DMC and DMDAAC could be polymerized alternately onto the starch backbone, providing long molecular chains and abundant positive charge for enzymatic hydrolysis of starch molecular chains. In addition to exploring the grafting of samples under reaction conditions, flocculants prepared under different conditions were used to flocculate 30 mg/L humic acid to further determine the role of grafting rate in the removal effect.

Production of low-protein cocoa powder with enzyme-assisted hydrolysis.

Amino acid-related disorders are caused by a defect in the metabolic pathways of amino acid groups. These patients must follow a lifelong protein diet. The objective of this study was to produce a low-protein cocoa powder (LPP) with enzymatic hydrolysis and precipitation method. First, the solubility of cocoa powder was increased by heat and enzyme treatments (Amylase, Viscozyme, and Alcalase). Then, the protein level was decreased by isoelectric precipitation. According to the obtained results, the solubility of cocoa powder rose from 28.61% to 50.69%. Protein content decreased by almost 40% and significant reductions in the amino acid profile were also provided; the highest ones were detected in methionine (100%), lysine (73.65%), leucine (53.64%), alanine (46.17%), and isoleucine (44.73%) levels. LPP had high phenolic content (25.10 mg/g GAE) and the changes in the antioxidant activities were not significant (p > .05). Moreover, chocolate production with LPP and control powder was also carried out under laboratory conditions. Hardness (1732.52 g), moisture content (0.60%), and water activity (0.37) of chocolate samples produced with low-protein cocoa powder (LPC) were lower than those of the control sample. The Casson model well fitted to the rheological data (R 2 > .990) and chocolate samples showed elastic behavior. The removal of proteins from the cocoa was verified with Fourier transform infrared spectroscopy analyses. The melting temperatures of chocolates (31.84 and 31.54°C for control and LPC samples, respectively) did not change with the applied process. As a conclusion, it was revealed that the production of low-protein cocoa powder and chocolate is feasible for patients with amino acid disorders with this study.

Preparation of food ingredients for the PKU patients: Two‐step enzymatic hydrolysis and activated carbon adsorption for the removal of phenylalanine from whey protein hydrolysates

In this study, we developed a two‐step enzymatic hydrolysis method followed by activated carbon adsorption to remove phenylalanine (Phe) from whey protein. The results showed that the free rate of Phe after sequential enzymatic hydrolysis of trypsin and flavorzyme was 90.8%. After adsorption by activated carbon No. 1, the removal efficiency of Phe from the hydrolysates reached 89.79% at 2.19 mg/g protein equivalent. Therefore, low Phe protein hydrolysates (LPHs) can be used to prepare low Phe food for phenylketonuria patients who cannot metabolise Phe properly by themselves and need to maintain a low Phe diet for life.

Application of antioxidant peptides derived from goat milk in ginger coffee formulation

Peptides can be obtained from the degradation of goat milk protein by enzymatic hydrolysis method using food-grade papain enzyme. These peptides have antioxidant activity that can be applied to beverage formulations. This study aimed to characterize antioxidative peptides from whey and goat milk and to develop a ginger coffee drink formulation with antioxidant peptides. Protein hydrolysis was performed for 0, 15, and 30 mins and the highest degree of hydrolysis was obtained from protein samples which were hydrolyzed for 15 mins. The whey hydrolysate 15 mins had a protein concentration of 0.54±0.07 mg/mL and one protein band of 17 kDa. Goat milk peptides had a protein concentration of 1.71±0.00 mg/mL and one protein band of 15 kDa. This sample also has the highest antioxidant activity, where Whey peptides had an antioxidant activity of 79.98±0.86% while goat's milk peptides 94.97±0.44%. These two peptides were applied to ginger coffee drink formulation. The formulations with the highest antioxidant activity were ginger coffee with goat milk and whey peptides in a ratio of 4:1 (90.15±1.02%) and ginger coffee with goat milk (85.23±1.15%). Based on results from the organoleptic test, these two formulations were also acceptable to panellists in terms of taste, overall properties, and interest.

Bioetanol dari Biji Nangka dengan Proses Likuifaksi dan Fermentasi menggunakan Saccharomyces Cerevisae

Potensi biji nangka (Arthocarphus heterophilus) belum dieksploitasi secara optimal. Biji nangka dapat diolah menjadi bahan baku pembuatan bioetanol. Penelitian ini menggunakan metode hidrolisis enzimatis dengan enzim α-amylase dan glukoamilase untuk memecah pati menjadi glucose dan metode fermentasi dapat mengubah glucose menjadi bioetanol menggunakan bakteri saccharomyces cerevisiae. Penelitian ini bertujuan untuk menentukan komposisi variasi penambahan enzim α-amylase dan glukoamilase yang relative baik, waktu fermentasi yang relative baik pada pembentukan bioethanol. Pembuatan bioethanol dilakukan dengan biji nangka 50gram, selanjutnya dikeringkan dengan oven suhu 150 0C selama 1jam, kemudian digiling, kemudian masuk ke proses hidrolisis dengan variabel komposisi penambahan enzim α-amylase dan glukoamilase (20; 30; 40; 50; 60ml) selanjutnya diuji menggunakan refraktometer brix. Selanjutnya, proses fermentasi dilakukan dengan menambahkan yeast Saccharomyces cereviseae dengan variasi lama fermentasi 24; 36; 48; 60; 72 jam. Hasil analisa menunjukkan kadar glukosa yang relatif baik diperoleh pada volume enzim alfa-amilase dan gluko-amilase sebanyak 60ml dengan kadar sebesar 14%. Pada proses fermentasi diperoleh kadar alkohol sebesar 40% dengan waktu fermentasi 60jam.

Undenatured type II collagen and its role in improving osteoarthritis.

Osteoarthritis (OA) is a degenerative joint disease, affecting 32.5 million US adults or 242 million people worldwide. There is no cure for OA. Many animal and clinical trials showed that oral administration of undenatured type II collagen could significantly reduce the incidence of OA or alleviate the symptoms of articular cartilage. Type II collagen is an important component of cartilage matrix. This article reviewed research progress of undenatured type II collagen including its methods of extraction and preparation, structure and characterization, solubility, thermal stability, gastrointestinal digestive stability, its role in improving OA, and the mechanism of its action in improving OA. Type II collagen has been extensively explored for its potential in improving arthritis. Methods of extraction of type II collagen are inefficient and tedious. The method of limited enzymatic hydrolysis is mainly used to prepare soluble undenatured type II collagen (SC II). The solubility, thermal and gastrointestinal digestive stability of SC II are affected by the sources of raw material, pH, salt ions, and temperature. Oral administration of undenatured type II collagen improves OA, whereas its activity is affected by the sources, degree of denaturalization, intervention methods and doses. However, the influence of the structure of undenatured type II collagen on its activity and the mechanism are unclear. The findings in this review support that undenatured type II collagen can be used in the intervention or auxiliary intervention of patients with OA.

Recognizing the variation of DNA-P during and after the algal bloom in lake Hulun

Eutrophication has spread from shallow lakes in temperature zones to lakes in cold regions as a result of a continuous warm climate and human activities. Little proof for the importance of dissolved organic phosphorus (DOP) in contributing to phosphorus cycling and algae growth has been generated for aquatic ecosystems, particularly in cold eutrophic lakes. In this study, a comprehensive in situ study was conducted in overlying water, suspended particulate matter, and sediment during and after algal bloom (in July and September, respectively) in Lake Hulun. Multiple methods of 31P NMR, enzymatic hydrolysis, and UV–visible technologies were combined to detect phosphorus occurrence, bioavailability, and molecular structure from a novel angle. The 31P NMR analysis results showed that DNA-P is mainly stored in the dissolved phase and has not been detected in suspended particulate matter or sediment. Enzymatic hydrolysis was used to determine the bioavailability of DOP, which revealed that in July and September, respectively, 85% and 79% of DOP were hydrolyzable. UV–visible analysis represented that the degree of humification and molecular weight of DOP were high during the algal bloom, but these values considerably dropped following the algal bloom. The large amount of DNA-P present in the overlying water is the main reason for the high degree of humification and high molecular weight of the water body. Besides, Lake Hulun's DNA-P remains highly bioavailable during algal blooms, despite its high degree of humification and molecular weight. These findings can serve as a theoretical basis for understanding the migration and transformation of DOP, as well as the persistence of algal blooms in eutrophic lakes located in cold regions.

Acquisition, Characterization, and Optimization of Distilled Bioethanol Generated from Fermented Carrot (Daucus carota) Residues

Bioethanol is a liquid biofuel produced from the digestion of biomass and usable waste of organic origin. The objective of this research was to obtain bioethanol from carrot (Daucus carota) residues of the Peruvian Chantenay variety, with a high content of lignocellulosic substances. The in-batch process method of enzymatic hydrolysis, with Aspergillus niger amyloglucosidase, and fermentation, with Saccharomyces cerevisiae yeast, was applied. The ferment was steam distilled and chemically characterized. The process was evaluated by controlling pH and enzyme/yeast mass ratio through the response surface optimization. The optimum conditions for the best values of TSS and % ethanol content for the distilled product were a time of 300 min, yeast/enzyme mass ratio of 24.0, and pH of 4.98. The results showed a significant decrease in sugars in the hydrolysis and fermentation stages, optimum alcohol content in the distilled product of 92.48% (v/v), lower organic compound content, and net calorific value of 23.82 MJ/kg, which is higher than those reported in the literature.