Enzymatic modification of sesame seed protein,sourced from waste resource for nutraceutical application

The functional characteristics which include protein solubility at different pH, emulsifying and foaming properties, degree of hydrolysis, molecular weight distribution, antioxidant and ACE inhibitory activity of sesame protein hydrolysates prepared with pepsin, papain and alcalase enzymes were evaluated. The rate of degree of hydrolysis was found to reach maximum (25–30%) within the first time fragment i.e 10 min but 80% of hydrolysis was obtained in 120 min with alcalase. SDS-PAGE of hydrolysates with papain, pepsin and alcalase evinced bands of low molecular weight protein of 14.3 kDa and even lower for alcalase treatment of 120 min. Hydrolysates so formed were of improved functional properties as evident from emulsifying and foaming property. Hydrolysis with different proteases enhanced the protein solubility significantly at pH 7.0. Antioxidative assay revealed radical scavenging activity of the hydrolysates with papain hydrolysates showing maximum antioxidative efficacy. The ultra-filtered peptide fractions which showed comparable ACE inhibitory activity were sequenced by MALDI-TOF and matched to that of previously identified ACE inhibitory peptides. The results corroborate the ACE inhibitory effect of the peptides. Hence, these highly bioactive protein hydrolysates produced from waste sesame meals can be successfully employed in various functional food formulations.     

脱色猪血红蛋白酶解产物制备及其抗氧化性

通过复合蛋白酶(Pancreatin and Protamex)酶解制备了猪血红蛋白酶解产物,将其产物采用活性炭吸附脱色.酶解产物的分子量范围在＞15 kDa～＜1 kDa(游离氨基酸)之间,脱色酶解产物的分子量范围大部分＜5 kDa.脱色祛除94.36%的高铁血红素从而改善终产物的色泽.酶解产物及脱色产物具有还原力和DPPH自由基清除能力.猪血红蛋白酶解产物的抗氧化活性依赖于其分子量和氨基酸组成.     

Comparative analysis of the processes of collagen concentration by ultrafiltration using different types of membranes

Tangential flow filtration of the collagen protein solutions with a molecular weight 12, 14, and 24 kDa is investigated using flat sheet membranes. The effects of tangential ultrafiltration (UF) on the permeate properties using two regenerated celluloses (RCs) and two polyethersulfone (PES) membranes with molecular weight cut-off (MWCO) of 5 and 10 kDa are reported. The permeate and concentrate obtained in the UF experiments are characterized from a physical–chemical point of view by determining the temperature, pH, electrical conductivity, nitrogen content, and protein concentration. In addition, the experimental data are modeled using Hermia's model. The UF experiments demonstrated that permeate flux declined with increasing molecular weight of collagen at constant concentration (1%). Regardless of the molecular weight of collagen, the rejections decrease in the following order: PES 5 kDa > RC5kDa > RC10kDa > PES10kDa. In case of membrane with higher MWCO, the clogging phenomenon is mainly due to the blockage of the internal pores of the membrane than the formation of a polarization layer. Morphologies and characteristics of the membranes are characterized using scanning electron microscopy.     

Development of a pilot process for the production of alfalfa peptide isolate

Enzymatic membrane reactors are widely used to produce protein hydrolysates. During the past few years, leaf extracts have been recognised as a good source of high quality protein. The interest in alfalfa protein concentrate (APC), a hydrophobic protein with excellent functional and nutritional properties, is due to its abundance, to its amino acid composition and to its ribulose 1,5‐biphosphate carboxylase–oxygenase content. In order to use this potential protein source in various fields (food, pharmaceutical and cosmetic industries), a pilot process for APC hydrolysis in a continuous stirred tank membrane reactor (CSTMR) was carried out. At pH 9.5 and 40 °C, the hydrolysis of APC (30.6 g dm^?3) by Delvolase (2.4 g dm^?3) with a residence time of 180 min, gave a conversion of 759 g kg^?1 protein at steady state. Coupling the reactor with an inorganic ultrafiltration membrane (Carbosep M5) with a 10 kDa nominal molecular weight cut‐off (NMWCO), allowed production of a soluble and reproducible peptide permeate with 23 g dm^?3 of hydrolysed protein. Phenolic compounds, responsible for the brown colour of the permeate, were removed at pH 5.0 and room temperature by anion‐exchange chromatography using Amberlite IRA900Cl, with a yield of 920 g kg^?1. After electrodialysis and spray‐drying of the decolorised permeate, an alfalfa peptide isolate (API) was obtained. It was soluble over the full pH range and its amino acid composition was comparable to that of the FAO/WHO standard. It could be used as a protein supplement in human diets and other fields. Copyright © 2003 Society of Chemical Industry     

A Compatible Membrane Process for Separation and Concentration of Pediocin PA-1 from Fermentation Broth

This work describes an effective combined ultrafiltration (UF)-nanofiltration (NF) membrane process for the separation and concentration of pediocin PA-1 from fermentation broth. Three polysulfone (PS) membranes with MWCOs of 5, 10, and 30 kDa were tested for ultrafiltration effectiveness. The 10 kDa membrane was selected because it displayed high permeability, good pediocin PA-1 recovery and reduced fouling. When the volume concentration factor (VCF) of UF reached 2.5, continuous diafiltration (DF) was carried out. The optimal diafiltration factor (DFF) was 1. The permeate obtained from UF was then concentrated by NF. When the VCF of NF reached 4.5, pediocin PA-1 recovery loss was only 10.5%. This two-stage membrane process improved the loading solutions by 4.5-fold, allowing up to 71.6% recovery of pediocin PA-1. After the membrane process, the NF retentate could be concentrated and subjected to preparative chromatography to obtain purified pediocin PA-1, or it could be dried to obtain a rich pediocin PA-1 preservative.     

红豆杉单组分多糖的超滤预处理及连续分离工艺

以红豆杉枝叶部位总多糖为原料,采用超滤方法对原料进行预处理,并对工艺进行优化,最佳优化条件为:截留相对分子质量为5kDa,温度为25℃,压力为20psi(1psi=6894.76kPa),pH值为6.8。 在此条件下,将浓度为10g/L的1L红豆杉多糖溶液超滤至125mL,再添加去离子水至1L,反复超滤4次,得到的红豆杉多糖的截留率和脱色率分别为87.2%和75.6%。进一步以红豆杉单组分多糖间歇色谱分离工艺参数为基础,采用自行设计制作的连续色谱设备,建立了连续离子交换色谱分离红豆杉酸性单组分多糖PST-1的分离工艺,处理量达到每批次100.08L,PST-1纯度在99.0%以上,收率达到50.0%。     

Antioxidant effects of protein hydrolysates in the reaction with glucose

Maillard reaction products (MRP) obtained by reaction between glucose and protein hydrolysates from casein and fish were investigated. The influence of parameters such as reaction time and glucose concentration was studied. The antioxidative activity of MRP was determined by using the β-carotene/linoleate model and the 1,1-diphenyl-2-pricrylhydrazyl method. All experiments showed that the antioxidative effect was improved by 20–30% when the hydrolysates were reached with glucose. A dramatic increase in antiradical efficiency of the MRP (up to 75%) was also observed. The study of the chromatographic profiles obtained before and after the Maillard reaction found changes in absorbance at 280 nm, indicating molecular rearrangements that could be involved in the improvement of the antioxidative and free radical-scavenging activities.     

Characterization of Peptides Found in Unprocessed and Extruded Amaranth (Amaranthus hypochondriacus) Pepsin/Pancreatin Hydrolysates

The objectives of this study were to characterize peptides found in unprocessed amaranth hydrolysates (UAH) and extruded amaranth hydrolysates (EAH) and to determine the effect of the hydrolysis time on the profile of peptides produced. Amaranth grain was extruded in a single screw extruder at 125 °C of extrusion temperature and 130 rpm of screw speed. Unprocessed and extruded amaranth flour were hydrolyzed with pepsin/pancreatin enzymes following a kinetic at 10, 25, 60, 90, 120 and 180 min for each enzyme. After 180 min of pepsin hydrolysis, aliquots were taken at each time during pancreatin hydrolysis to characterize the hydrolysates by MALDI-TOF/MS-MS. Molecular masses (MM) (527, 567, 802, 984, 1295, 1545, 2034 and 2064 Da) of peptides appeared consistently during hydrolysis, showing high intensity at 10 min (2064 Da), 120 min (802 Da) and 180 min (567 Da) in UAH. EAH showed high intensity at 10 min (2034 Da) and 120 min (984, 1295 and 1545 Da). Extrusion produced more peptides with MM lower than 1000 Da immediately after 10 min of hydrolysis. Hydrolysis time impacted on the peptide profile, as longer the time lower the MM in both amaranth hydrolysates. Sequences obtained were analyzed for their biological activity at BIOPEP, showing important inhibitory activities related to chronic diseases. These peptides could be used as a food ingredient/supplement in a healthy diet to prevent the risk to develop chronic diseases.     

Evaluation of membrane fouling and flux decline related with mass transport in nanofiltration of tartrazine solution

BACKGROUND: This work was carried out to investigate and analyze the interrelated dynamics of mass transport, membrane fouling and flux decline during nanofiltration of tartrazine. A combined application including pore diffusion transport model and a material balance approach was used to model an experimental flux data obtained from different values of pH (3, 5, 7 and 10), feed‐dye concentration (25, 100 and 400 mg L^?1), and transmembrane pressure (1200, 1800 and 2400 kPa). RESULTS: Almost 100% dye solution removal and a permeate flux of 135 L m^?2 h^?1 were obtained for 25 mg L^?1 and 1200 kPa at pH 10. At pH 10, lower membrane fouling was obtained due to the increase of electrostatic repulsion between anionic dye molecules and the more negatively charged membrane surface. Flux decline and membrane fouling increased together with transmembrane pressure and dye concentration. Fouling was found to be directly related to proportional‐permeation coefficient (k_O′) of dye which was identified as the solute passing into the permeate with respect to the amount transported into the membrane from the feed. CONCLUSIONS: For a decrease of pH (10 to 3) and transmembrane pressure (2400 to 1200 kPa) or an increase of feed‐dye concentration (25 to 400 mg L^?1), fewer dye molecules passed into the permeate with respect to the amount transported into the membrane from the feed. This situation depended mainly on the combined influences of the gel layer and fouling in the membrane. Copyright © 2010 Society of Chemical Industry     

Ultrafiltration of Wastewater from Isolated Soy Protein Production: Fouling Tendencies and Mechanisms

Membrane separation processes appear to be a good alternative in wastewater treatment systems. One of the biggest limitations is the decrease in permeate flux, which is caused mostly by concentration polarization and fouling phenomena. The extent of these phenomena are dependent on the interactions between the different solution compounds, membrane-solution interactions, and the operating conditions. The fouling tendencies of three different commercial tubular ceramic membranes (5, 20, and 50 kDa) during the ultrafiltration of an isolated soy protein (ISP) wastewater were evaluated through determination of the water permeate flux before and after the wastewater ultrafiltration and using Hermia's Model. The wastewater from ISP production is a complex solution characterized by a very high organic load: reaches COD values greater than 18,000 mg · L^?1. The wastewater proteins are small molecules (8 to 50 kDa) that could not be removed during the industrial processing. The recovery of these small proteins and their return to the ISP production process would result in both economical and environmental benefits by increasing the final product yield and reducing significantly the wastewater organic load. All the membranes tested presented a large fouling tendency: 65% (5 kDa membrane), 69% (20 kDa membrane) and 76% (50 kDa membrane). The best fit to Hermia's Model for all of the UF membranes was obtained by the complete blocking model.     

Analysis and optimization of the influence of operating conditions in the ultrafiltration of macromolecules using a response surface methodological approach

In this work, the ultrafiltration of macromolecules was analysed using a response surface methodological approach. The behaviour of two different inorganic membranes was investigated. The membranes selected were a Carbosep M2 membrane (Orelis, France) with a molecular weight cut-off (MWCO) of 15 kDa and a Tami MSKT membrane (Tami Industries, France) with a MWCO of 5 kDa. The solute employed was polyethylene glycol of 35 kDa molecular weight. The influence of transmembrane pressure (0.1, 0.2, 0.3, 0.4 and 0.5 MPa), crossflow velocity (1, 2 and 3 m/s) and feed concentration (5, 10 and 15 g/L) on permeate flux and permeate flux decline was investigated. Analysis of variance was proved to be a useful tool to determine the effect of operating variables on both parameters. The method used demonstrated the presence of coupled effects between factors as well as squared effects that are relevant to the ultrafiltration process. The surface contours obtained from fitted models were used for the optimization of the operating conditions. The goal was to simultaneously maximize the average permeate flux and minimize the flux decline. The optimal operating conditions for the Carbosep M2 membrane were a transmembrane pressure of 0.38 MPa and a crossflow velocity of 3 m/s. The optimal operating conditions for the Tami MSKT membrane could not be determined by means of multiple response optimization due to the low accuracy of the regression model obtained for the cumulative permeate flux decline (SFD) response variable.     

Effect of pH on Separation Performances in High-Performance Liquid Chromatography of Antibacterial Peptides from the Spleen of Japanese eel,Anguilla japonica

The present study was made to determine the optimum pH for isolating antibacterial peptides from the spleen of Japanese eel, Anguilla japonica, by high-performance liquid chromatography (HPLC). The recovery rates of the peptides were investigated by using buffers with three pH values (pH 3, pH 4, and pH 5) in ion-exchange chromatography (IEC) of the spleen protein sample with the molecular weight (MW) < 10 kDa. Following this, for the fractions obtained from IEC, we continued to study the effect of four pH values (pH 2, pH 7, pH 9, and pH 12) on the separation efficiency in reverse-phase high-performance liquid chromatography (RP-HPLC). The results showed using the buffer with pH 4 in IEC could achieve the highest rate of recovery, which was 5.4 fold to that of pH 3 and 1.36 fold to that of pH 5. The treatment at high pH value (pH 9) did significantly affect the chromatographic separation behaviors, which produced more than twice the peak numbers than those in other three pH values. The optimized pH would be helpful for isolating antibacterial peptides from the spleen of eel.     

Micro method for stereospecific analysis of triacyl-sn-glycerols by chiral-phase high-performance liquid chromatography

A procedure for micro stereospecific analysis of triacyl-sn-glycerols (TGs) by high-performance liquid chromatography (HPLC) on a chiral column is presented. TGs were partially hydrolyzed with ethyl magnesium bromide, and total products were immediately converted to 3,5-dinitro-phenylurethane derivatives. Each of the 1- and 2-monoacylglycerol (MG) derivatives was isolated by HPLC on a silica column. The 1-MGs were resolved intosn-1 andsn-3 MG fractions by HPLC on a Sumichiral OA-4100 column (Sumitomo Chemical, Osaka, Japan). Fatty acid methyl esters obtained from thesn-1,sn-2 andsn-3 MG fractions were analyzed by gas-liquid chromatography on a capillary column. Analyses of standard TGs showed that, even with 1 mg of sample, accuracy was comparable to that obtained with 100-mg samples. Applying this procedure to the stereospecific analysis of 5 mg of jujube pulp, TGs revealed the positional distribution of the (n-5) series of monounsaturated fatty acids they contained. Honored Student Award Address presented at the 83rd AOCS Annual Meeting held in Toronto, Canada, May 10–14, 1992.     

Films made from polyethylene‐co‐acrylic acid and soluble biopolymers sourced from agricultural and municipal biowaste

Blends were obtained from polyethylene‐co‐acrylic acid (PEAA) with 248 kDa molecular weight and two water soluble biopolymers isolated from the hydrolysate of postharvest tomato plant and urban biowaste compost. The two hydrolysates were constituted respectively from a polysaccharide (SP) with 27 kDa molecular weight and a lignin‐like polymer (LP) with 75 kDa molecular weight containing aliphatic and aromatic C moieties substituted by carboxyl, hydroxyl, and amino groups. Evidence was obtained for reactions occurring between the biopolymers and the synthetic polymer leading to new polymers with 151 to 1243 kDa molecular weights. The thermal and mechanical properties of the blends were studied. Compared with neat PEAA, the PEAA‐LP blends containing 5 to 10% LP exhibited 2 to 5× higher molecular weights, 10 to 50% lower crystallinity, 2 to 6× higher Young's modulus, over 3× higher stress at yield point and somewhat lower strain at break (55–280% vs. over 300%). On the contrary the PEAA‐SP blends exhibited 6 to 13% lower crystallinity and the same mechanical properties as neat PEAA. The results offer scope for investigating biopolymers sourced from other biowastes to understand more the reasons of the observed effects and exploit their full potential to modify or to replace synthetic polymers. Perspectives of economic and environmental benefits are discussed. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41909.     

刺苋的化学成分研究

目的：研究刺苋的化学成分。方法：用硅胶柱色谱法、SephadexLH-20柱色谱法MCI及HPLC进行分离纯化,依据理化性质和光谱数据鉴定化合物结构。结果：从刺苋中得到七种分离物：齐墩果酸（1）;槲皮素-3-O—β—D葡萄糖甙（2）;3’-甲氧基-槲皮素-3-O-β—D葡萄糖甙（3）;3’-甲氧基-槲皮素-3-O-α-L一鼠李糖-3-O-β-D-葡萄糖甙（4）;△5.22豆甾醇（5）;β-谷甾醇（6）;△5.22豆甾醇-3-O-β-D-葡萄糖甙（7）。     

Purification of Ellagic Acid by UF Membranes

Ellagic acid (2, 3, 7, 8‐tetrahydroxy(1)benzopyrano(5, 4, 3‐cde)(1)benzopyran‐5, 10‐dione) was selected as a model pollutant which is present in the tannic fraction of cork processing wastewater. The ultrafiltration of aqueous ellagic acid solutions through three membranes was studied in tangential UF laboratory equipment. Two of the membranes were polyethersulfone (Biomax10K and Biomax5K, with MWCO of 10000 and 5000 Da, respectively), and the third made of regenerated cellulose (Ultracel5K, with MWCO of 5000 Da). The water hydraulic permeability was evaluated for each membrane. The evolution of the permeate flow rate with processing time was followed, and the influence of the main operating variables (feed flow rate, trans‐membrane pressure and nature of the membranes) on the permeate flux was also established. According to the hypothesis of the film theory, the intrinsic and apparent rejection coefficients, as well as the mass transfer coefficients, were also determined, and the values obtained were discussed as a function of the operating conditions used.     

Enhancing ACE-inhibition of food protein hydrolysates by selective adsorption using porous carbon materials

Bioactive peptides from food proteins such as natural ACE (angiotensin-converting enzyme)-inhibitors have attracted particular attention for their potential to prevent hypertension. ACE-inhibiting peptides were enriched from food protein hydrolysates prepared from α-lactalbumin and lysozyme by selective adsorption on microporous activated carbons. For the eluate, it was shown by liquid chromatography that the strongest inhibitor isoleucyl-tryptophan was enriched by a factor of 11.2 compared to the initial α-lactalbumin hydrolysate. Natural inhibitors derived from lysozyme hydrolysates (e.g., alanyl-tryptophan) were successfully enriched as well. Identification of the enriched peptide fraction by mass spectroscopy revealed the hydrophobic character of the enriched peptides. The molecular weight distribution of the enriched peptide fraction can be controlled by the pore size distribution of the chosen adsorbent, which was proven by size exclusion chromatography of enriched peptide fractions derived from three different model carbons differing in their pore size. The selective enrichment of natural ACE-inhibitors from the α-lactalbumin hydrolysate lead to a 6 times stronger in vitro ACE-inhibition demonstrating the high potential as ingredients for hypotensive functional foods with reduced side effects.     

Downstream Processes for Aqueous Enzymatic Extraction of Rapeseed Oil and Protein Hydrolysates

Downstream processes following aqueous enzymatic extraction (AEE) of rapeseed oil and protein hydrolysates were developed to enhance the oil and protein yields as well as to purify the protein hydrolysates. The wet precipitate (meal residue) from the AEE was washed with twofold water at 60 °C, pH 11 for 1 h. Emulsions from the AEE and the washing step were pooled and submitted to a stepwise demulsification procedure consisting of storage-centrifugation and freezing–thawing followed by centrifugation. Aqueous phases were pooled and adsorbed onto macroporous adsorption resins (MAR) to remove salts and sugars. Following extensive rinsing with deionized water (pH 4), desorption was achieved by washing with 85% ethanol (v/v) to obtain crude rapeseed peptides (CRPs). In a separate experiment, stepwise desorption was carried out with 25, 55, and 85% ethanol to separate the bitter peptides from the other peptides. Using a combination of the AEE process, washing and demulsification steps, the yields of the total free oil and protein hydrolysates were 88–90% and 94–97%, respectively. The protein recovery was 66.7% and the protein content was enriched from 47.04 to 73.51% in the CRPs. No glucosinolates and phytic acid were detected in the CRPs. From the stepwise desorption, a non-bitter fraction RP25 (containing 64–66% of total desorbed protein) had a bland color and significantly higher protein content (81.04%) and hence was the more desirable product.     

Isolation of an active peptide fragment from human serum albumin and its synergism with α-tocopherol

An active peptide was isolated from hydrolysates of human serum albumin. This peptide was initially isolated by gel permeation chromatography and subsequent reversed-phase high-performance liquid chromatography. This active peptide, composed of 10 amino acid residues, was further hydrolyzed with a lysyl endopeptidase to give two peptide fragments. Only one fragment, identified as the tetrapeptide Leu-Gln-His-Lys, was found to have activity comparable to the original peptide and corresponded to the amino acid residues 103–106 of human serum albumin. Among these four amino acid residues, the His-Lys sequence seemed to be important in the occurrence of potent activity by comparison of the structural similarity with another active tetrapeptide, Asp-Thr-His-Lys, which had been previously isolated from bovine serum albumin hydrolysates. In addition, the active fragment showed potent synergism by preventing consumption of α-tocopherol during the autoxidation of linoleic acid.     

Ultrafiltration: a means for decolorization of cane sugar solution

Membrane ultrafiltration was used for clarification as well as for decolorization of raw brown sugar obtained from the Indian sugar industry. Experimental results were obtained using sugar solutions of 28 and 46°Brix and mineral membranes of 20 nm, 5 and 1 kDa molecular weight cut-off (MWCO) on an industrial size pilot plant under different operating conditions. It was found that, even with the membrane of MWCO of 1 kDa, the maximum color removal was limited to 58.67% and steady-state permeate flux was only 29 1/h m² for the 46°Brix sugar solution. Empirical relationships between membrane performance (for decolorization and clarification) and membrane pore diameter were obtained from the experimental results. In order to obtain very high quality white crystalline sugar, further processing with adsorbents or use of an ion-exchange technique is required.