Efeito do teor de umidade sobre o pré-tratamento a vapor e a hidrólise enzimática do bagaço de cana-de-açúcar

The effect of moisture content in the steam treatment and enzymatic hydrolysis of sugarcane bagasse was evaluated. Steam treatment was perfomed at 195-210 ºC for 4-8 min using cane bagasse with moisture contents in the range 16-100 wt% (dry basis). Increased moisture contents not only had a positive influence in recovery of main cane biomass components but also resulted in better substrates for enzymatic hydrolysis. As a result, drying is not required for optimal pretreatment and enzymatic hydrolysis of sugarcane bagasse, which can be processed into second generation ethanol immediately after crushing and hot water washing.

Hydrolytic activity of bacterial lipases in amazonian vegetable oils

The data presented describe the development of an enzymatic process in vegetable oils. Six bacterial lipases were tested for their ability to hydrolyze. For each lipase assay, the p-NPP method was applied to obtain maximum enzymatic activities. The lipase from Burkholderia cepacia (lipase B-10) was the most effective in buriti oil, releasing 4840 µmol p-NP mL-1. The lipase from Klebsiella variicola (lipase B-22) was superior in passion fruit oil, releasing 4140 µmol p-NP mL-1 and also in babassu palm oil, releasing 2934 µmol p-NP mL-1. Research into the bioprocessing of oils aims to provide added value for this regional raw material.

Cuticular and Suberin Polymers of Edible Plants. Analysis by Gas Chromatographic-Mass Spectrometric and Solid State Spectroscopic Methods

Cutin and suberin are structural and protective polymers of plant surfaces. The epidermal cells of the aerial parts of plants are covered with an extracellular cuticular layer, which consists of polyester cutin, highly resistant cutan, cuticular waxes and polysaccharides which link the layer to the epidermal cells. A similar protective layer is formed by a polyaromatic-polyaliphatic biopolymer suberin, which is present particularly in the cell walls of the phellem layer of periderm of the underground parts of plants (e.g. roots and tubers) and the bark of trees. In addition, suberization is also a major factor in wound healing and wound periderm formation regardless of the plants’ tissue. Knowledge of the composition and functions of cuticular and suberin polymers is important for understanding the physiological properties for the plants and for nutritional quality when these plants are consumed as foods. The aims of the practical work were to assess the chemical composition of cuticular polymers of several northern berries and seeds and suberin of two varieties of potatoes. Cutin and suberin were studied as isolated polymers and further after depolymerization as soluble monomers and solid residues. Chemical and enzymatic depolymerization techniques were compared and a new chemical depolymerization method was developed. Gas chromatographic analysis with mass spectrometric detection (GC-MS) was used to assess the monomer compositions. Polymer investigations were conducted with solid state carbon-13 cross polarization magic angle spinning nuclear magnetic resonance spectroscopy (13C CP-MAS NMR), Fourier transform infrared spectroscopy (FTIR) and microscopic analysis. Furthermore, the development of suberin over one year of post-harvest storage was investigated and the cuticular layers from berries grown in the North and South of Finland were compared. The results show that the amounts of isolated cuticular layers and cutin monomers, as well as monomeric compositions vary greatly between the berries. The monomer composition of seeds was found to differ from the corresponding berry peel monomers. The berry cutin monomers were composed mostly of long-chain aliphatic ω-hydroxy acids, with various mid-chain functionalities (double-bonds, epoxy, hydroxy and keto groups). Substituted α,ω-diacids predominated over ω-hydroxy acids in potato suberin monomers and slight differences were found between the varieties. The newly-developed closed tube chemical method was found to be suitable for cutin and suberin analysis and preferred over the solvent-consuming and laborious reflux method. Enzymatic hydrolysis with cutinase was less effective than chemical methanolysis and showed specificity towards α,ω-diacid bonds. According to ₁₃C CP-MAS NMR and FTIR, the depolymerization residues contained significant amounts of aromatic structures, polysaccharides and possible cutan-type aliphatic moieties. Cultivation location seems to have effect on cuticular composition. The materials studied contained significant amounts of different types of biopolymers that could be utilized for several purposes with or without further processing. The importance of the so-called waste material from industrial processes of berries and potatoes as a source of either dietary fiber or specialty chemicals should be further investigated in detail. The evident impact of cuticular and suberin polymers, among other fiber components, on human health should be investigated in clinical trials. These by-product materials may be used as value-added fiber fractions in the food industry and as raw materials for specialty chemicals such as lubricants and emulsifiers, or as building blocks for novel polymers.

Purified lignin for demanding applications

Diplomityön tarkoituksena oli puhdistaa kraft ligniiniä. Raaka-aineena käytettiin pääasiassa Lignoboost -menetelmän kaltaisella menetelmällä havupuu- mustalipeästä saostettua ligniiniä. Diplomityön ensimmäisenä tavoitteena oli löytää menetelmä, jolla voidaan poistaa kraft ligniinistä tuhkaa. Työssä raaka-aineena käytetyn saostetun ligniinin tuhkapitoisuus oli noin 3 %. Tarkoituksena oli saada laskettua tuhkapitoisuutta uudelleenlieton, suodatuksen ja pesun avulla. Työn toisena tavoitteena oli hiilihydraattien poisto kraft ligniinistä. Hiilihydraatit, pääosin hemiselluloosaa, ovat kiinnittyneet ligniiniin vahvoin kovalenttisin sidoksin. Aiempien kokemusten perusteella hemiselluloosat eivät irtoa ligniinistä vesipesun yhteydessä, vaan niiden irrottaminen vaatii onnistuakseen happo-, entsyymi- tai mikrobikäsittelyn, mikäli halutaan säilyttää ligniinin rakenne muuttumattomana. Tässä työssä käytetyt kraft ligniinin puhdistusmenetelmät olivat lietto, happohydrolyysi ja entsymaattinen hydrolyysi, joista kumpikin sisälsi ligniinin uudelleenlieton, suodatuksen ja muodostuneen kakun pesun vedellä.

Pressure filtration characteristics of enzymatically hydrolyzed biomass suspensions

Enzymatic hydrolysis of lignocellulosic polymers is likely to become one of the key technologies enabling industrial production of liquid biofuels and chemicals from lignocellulosic biomass. Certain types of enzymes are able to hydrolyze cellulose and hemicellulose polymers to shorter units and finally to sugar monomers. These monomeric sugars are environmentally acceptable carbon sources for the production of liquid biofuels, such as bioethanol, and other chemicals, such as organic acids. Liquid biofuels in particular have been shown to contribute to the reduction of net emissions of greenhouse gases. The solid residue of enzymatic hydrolysis is composed mainly of lignin and partially degraded fibers, while the liquid phase contains the produced sugars. It is usually necessary to separate these two phases at some point after the hydrolysis stage. Pressure filtration is an efficient technique for this separation. Solid-liquid separation of biomass suspensions is difficult, because biomass solids are able to retain high amounts of water, which cannot be readily liberated by mechanical separation techniques. Most importantly, the filter cakes formed from biomaterials are compressible, which ultimately means that the separation may not be much improved by increasing the filtration pressure. The use of filter aids can therefore facilitate the filtration significantly. On the other hand, the upstream process conditions have a major influence on the filtration process. This thesis investigates how enzymatic hydrolysis and related process conditions affect the filtration properties of a cardboard suspension. The experimental work consists of pressure filtration and characterization of hydrolysates. The study provides novel information about both issues, as the relationship between enzymatic hydrolysis conditions and subsequent filtration properties has so far not been considered in academic studies. The results of the work reveal that the final degree of hydrolysis is an important factor in the filtration stage. High hydrolysis yield generally increases the average specific cake resistance. Mixing during the hydrolysis stage resulted in undefined changes in the physical properties of the solid residue, causing a high filtration resistance when the mixing intensity was high. Theoretical processing of the mixing data led to an interesting observation: the average specific cake resistance was observed to be linearly proportional to the mixer shear stress. Another finding worth attention is that the size distributions of the solids did not change very dramatically during enzymatic hydrolysis. There was an observable size reduction during the first couple of hours, but after that the size reduction was minimal. Similarly, the size distribution of the suspended solids remained almost constant when the hydrolyzed suspension was subjected to intensive mixing. It was also found that the average specific cake resistance was successfully reduced by the use of filter aids. This reduction depended on the method of how the filter aids were applied. In order to obtain high filtration capacity, it is recommended to use the body feed mode, i.e. to mix the filter aid with the slurry prior to filtration. Regarding the quality of the filtrate, precoat filtration was observed to produce a clear filtrate with negligible suspended solids content, while the body feed filtrates were turbid, irrespective of which type of filter aid was used.

Topochemistry of physical and chemical pretreatments of biomass as investigated by FE-SEM, XPS and ToF-SIMS

Surface chemistry is of great importance in plant biomass engineering and applications. The surface chemical composition of biomass which includes lignin, carbohydrates and extractives influences its interactions with chemical agents, such as pulp processing/papermaking chemicals, or enzymes for different purposes. In this thesis, the changes in the surface chemical composition of lignocellulosic biomass after physical modification for the improvement of resulting paper properties and chemical treatment for the enhancement of enzymatic hydrolysis were investigated. Low consistency (LC) refining was used as physical treatment of bleached softwood and hardwood pulp samples, and the surface chemistry of refined samples was investigated. The refined pulp was analysed as whole pulp while the fines-free fibre samples were characterized separately. The fines produced in LCrefining contributed to an enlarged surface specific area as well as the change of surface coverage by lignin and extractives, as investigated by X-ray photoelectron spectroscopy (XPS). The surface coverage by lignin of the whole pulp decreased after refining while the surface coverage by extractives increased both for pine and eucalyptus. In the case of pine, the removal of fines resulted in reduction of the surface coverage by extractives, while the surface coverage by lignin increased on fibre sample (without fines). In the case of eucalyptus, the surface coverage by lignin of fibre samples decreased after the removal of fines. In addition, the surface distribution of carbohydrates, lignin and extractives of pine and eucalyptus samples was determined by Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS). LC-refining increased the amounts of pentose, hexose and extractives on the surface of pine samples. ToF-SIMS also gave clear evidence about xylan deposition and reduction of surface lignin distribution on the fibre of eucalyptus. However, the changes in the surface chemical composition during the physical treatment has led to an increase in the adsorption of fluorescent whitening agents (FWAs) on fibres due to a combination of electro-static forces, specific surface area of fibres and hydrophobic interactions. Various physicochemical pretreatments were conducted on wood and non-wood biomass for enhancing enzymatic hydrolysis of polysaccharides, and the surface chemistry of the pretreated and enzymatically hydrolysed samples was investigated by field emission scanning electron microscopy (FE-SEM), XPS and ToF-SIMS. A hydrotrope was used as a relatively novel pretreatment technology both in the case of wood and non-wood biomass. For comparison, ionic liquid and hydrothermal pretreatments were applied on softwood and hardwood as well. Thus, XPS analysis showed that the surface lignin was more efficiently removed by hydrotropic pretreatment compared to ionic liquid or hydrothermal pretreatments. SEM analysis also found that already at room temperature the ionic liquid pretreatments were more effective in swelling the fibres compared with hydrotropic pretreatment at elevated temperatures. The enzymatic hydrolysis yield of hardwood was enhanced due to the decrease in surface coverage of lignin, which was induced by hydrotropic treatment. However, hydrotropic pretreatment was not appropriate for softwood because of the predominance of guaiacyl lignin structure in this material. In addition, the reduction of surface lignin and xylan during pretreatment and subsequent increase in cellulose hydrolysis by enzyme could be observed from ToF-SIMS results. The characterisation of the non-wood biomass (e.g. sugarcane bagasse and common reed) treated by hydrotropic method, alkaline and alkaline hydrogen peroxide pretreatments were carried out by XPS and ToF-SIMS. According to the results, the action for the removal of the surface lignin of non-wood biomass by hydrotropic pretreatment was more significant compared to alkaline and alkaline hydrogen peroxide pretreatments, although a higher total amount of lignin could be removed by alkaline and alkaline hydrogen peroxide pretreatment. Furthermore, xylan could be remarkably more efficiently removed by hydrotropic method. Therefore, the glucan yield achieved from hydrotropic treated sample was higher than that from samples treated with alkaline or alkaline hydrogen peroxide. Through the use of ToF-SIMS, the distribution and localization of lignin and carbohydrates on the surface of ignocelluloses during pretreatment and enzymatic hydrolysis could be detected, and xylan degradation during enzymatic hydrolysis could also be assessed. Thus, based on the results from XPS and ToF-SIMS, the mechanism of the hydrotropic pretreatment in improving the accessibility of enzymes to fibre and further ameliorating of the enzymatic saccharification could be better elucidated.

Ionic liquid mediated biomass deconstruction: from analysis challenges to fermentable sugars

Ionic liquids, ILs, have recently been studied with accelerating interest to be used for a deconstruction/fractionation, dissolution or pretreatment processing method of lignocellulosic biomass. ILs are usually utilized combined with heat. Regarding lignocellulosic recalcitrance toward fractionation and IL utilization, most of the studies concern IL utilization in the biomass fermentation process prior to the enzymatic hydrolysis step. It has been demonstrated that IL-pretreatment gives more efficient hydrolysis of the biomass polysaccharides than enzymatic hydrolysis alone. Both cellulose (especially cellulose) and lignin are very resistant towards fractionation and even dissolution methods. As an example, it can be mentioned that softwood, hardwood and grass-type plant species have different types of lignin structures leading to the fact that softwood lignin (guaiacyl lignin dominates) is the most difficult to solubilize or chemically disrupt. In addition to the known conventional biomass processing methods, several ILs have also been found to efficiently dissolve either cellulose and/or wood samples – different ILs are suitable for different purposes. An IL treatment of wood usually results in non-fibrous pulp, where lignin is not efficiently separated and wood components are selectively precipitated, as cellulose is not soluble or degradable in ionic liquids under mild conditions. Nevertheless, new ILs capable of rather good fractionation performance have recently emerged. The capability of the IL to dissolve or deconstruct wood or cellulose depends on several factors, (e.g. sample origin, the particle size of the biomass, mechanical treatments as pulverization, initial biomassto-IL ratio, water content of the biomass, possible impurities of IL, reaction conditions, temperature etc). The aim of this study was to obtain (fermentable) saccharides and other valuable chemicals from wood by a combined heat and IL-treatment. Thermal treatments alone contribute to the degradation of polysaccharides (e.g. 150 °C alone is said to cause the degradation of polysaccharides), thus temperatures below that should be used, if the research interest lies on the IL effectiveness. On the other hand, the efficiency of the IL-treatment can also be enhanced to combine other treatment methods, (e.g. microwave heating). The samples of spruce, pine and birch sawdust were treated with either 1-Ethyl-3-methylimidazolium chloride, Emim Cl, or 1-Ethyl-3-methylimidazolium acetate, Emim Ac, (or with ionized water for comparison) at various temperatures (where focus was between 80 and 120 °C). The samples were withdrawn at fixed time intervals (the main interest treatment time area lied between 0 and 100 hours). Double experiments were executed. The selected mono- and disaccharides, as well as their known degradation products, 5-hydroxymethylfurfural, 5-HMF, and furfural were analyzed with capillary electrophoresis, CE, and high-performance liquid chromatography, HPLC. Initially, even GC and GC-MS were utilized. Galactose, glucose, mannose and xylose were the main monosaccharides that were present in the wood samples exposed to ILs at elevated temperatures; in addition, furfural and 5-HMF were detected; moreover, the quantitative amount of the two latter ones were naturally increasing in line with the heating time or the IL:wood ratio.

Production, isolation and characterization of bioactive peptides with antihypertensive properties from rapeseed and potato protein

Consumers’ increasing awareness of healthiness and sustainability of food presents a great challenge to food industry to develop healthier, biologically active and sustainable food products. Bioactive peptides derived from food proteins are known to possess various biological activities. Among the activities, the most widely studied are antioxidant activities and angiotensin I converting enzyme (ACE) inhibitory activity related to blood pressure regulation and antihypertensive effects. Meanwhile, vast amounts of byproducts with high protein content are produced in food industry, for example potato and rapeseed industries. The utilization of these by-products could be enhanced by using them as a raw material for bioactive peptides. The objective of the present study was to investigate the production of bioactive peptides with ACE inhibitory and antioxidant properties from rapeseed and potato proteins. Enzymatic hydrolysis and fermentation were utilized for peptide production, ultrafiltration and solid-phase extraction were used to concentrate the active peptides, the peptides were fractionated with liquid chromatographic processes, and the peptides with the highest ACE inhibitory capacities were putified and analyzed with Maldi-Tof/Tof to identify the active peptide sequences. The bioavailability of the ACE inhibitory peptides was elucidated with an in vitro digestion model and the antihypertensive effects in vivo of rapeseed peptide concentrates were investigated with a preventive premise in 2K1C rats. The results showed that rapeseed and potato proteins are rich sources of ACE inhibitory and antioxidant peptides. Enzymatic hydrolysis released the peptides effectively whereas fermentation produced lower activities.The native enzymes of potato were also able to release ACE inhibitory peptides from potato proteins without the addition of exogenous enzymes. The rapeseed peptide concentrate was capable of preventing the development of hypertension in vivo in 2K1C rats, but the quality of rapeseed meal used as raw material was found to affect considerably the antihypertensive effects and the composition of the peptide fraction.

Entsyymien talteenotto ja kierrätys selluloosaetanolin valmistuksessa

Bioetanolin valmistus selluloosapitoisista raaka-aineista vaatii selluloosapolymeerien pilkkomisen liukoisiksi sokereiksi. Tämä voidaan toteuttaa entsymaattisella hydrolyysillä. Selluloosan pilkkomiseen tarkoitetut entsyymit, sellulaasit, ovat entsymaattisen hydrolyysin jälkeen sitoutuneet joko kiintoainefaasiin tai ovat nestemäisessä faasissa ns. vapaina entsyymeinä. Prosessin taloudellisuuden kannalta on erityisen tärkeää minimoida siinä käytettävien entsyymien tarve, sillä tehokkaat entsyymivalmisteet ovat suhteellisen kalliita. Yksi varteenotettava vaihtoehto bioetanoliprosessin saamiseksi taloudellisemmaksi on käytettyjen entsyymien talteenotto ja kierrätys. Työn tarkoituksena oli selvittää kirjallisuudesta, millaisia menetelmiä on kehitetty entsyymien talteenottoon ja kierrätykseen lignoselluloosasta valmistettavan bioetanolin valmistuksessa. Työssä on keskitytty tuoreisiin tutkimuksiin ja menetelmien käyttökelpoisuuteen ja taloudellisuuteen. Viime vuosina sellulaasien talteenotto- ja kierrätysmenetelmiä koskevat tutkimukset ovat keskittyneet pääasiassa käsittelemään nanopartikkelien avulla tapahtuvaa entsyymien immobilisointia, ultrasuodatusta, erilaisia desorptiomenetelmiä, kiinteän hydrolyysijäännöksen kierrättämistä, tuoreen substraatin lisäämistä sekä myös tislausvaiheen jälkeistä entsyymien kierrättämistä. Jotta kierrätysmenetelmä olisi tehokas, tulisi sen pyrkiä säilyttämään entsyymien aktiivisuuksia, sokerisaantoa menettämättä ja sisältää sekä neste-, että kiintoainefaasista tapahtuva kierrätys. Jokaisella kierrätysmenetelmällä on hyvät ja huonot puolensa. Entsyymien talteenottoastetta saadaan kuitenkin parannettua yhdistämällä erilaisia menetelmiä. Useista tutkimuksista huolimatta, taloudellisinta ja käyttökelpoisinta entsyymien talteenotto- ja kierrätysmenetelmää ei ole vielä saavutettu.

Isolation and Characterization of Ovomucin - a Bioactive Agent of Egg White

The hen’s egg is a source of new life. Therefore, it contains many biologically active compounds. In addition to being a very nutritious food and also commonly used in the food industry due to its many techno-functional properties, the egg can serve as a source of compounds used as nutra-, pharmaand cosmeceuticals. One such interesting compound is ovomucin, an egg white protein responsible for the gel-like properties of thick egg white. Previous studies have indicated that ovomucin and ovomucin-derived peptides have several different bioactive properties. The objectives of the present study were to develop isolation methods for ovomucin, to characterize the structure of ovomucin, to compare various egg fractions as sources of ovomucin, to study the effects of various dissolving methods for ovomucin, and to investigate the bioactive properties of ovomucin and ovomucin-derived peptides. A simple and rapid method for crude ovomucin separation was developed. By using this method crude ovomucin was isolated within hours, compared to the 1-2 days (including a dialysis step) needed when using several other methods. Structural characterization revealed that ovomucin is composed of two subunits, α- and β-ovomucin, as egg white protein formerly called α1-ovomucin seemed to be ovostatin. However, it might be possible that ovostatin is associated within β- and α-ovomucin. This interaction could even have some effect on the physical nature of various egg white layers. Although filtration by-product fraction was a very prominent source of both crude and β-ovomucin, process development has reduced its amount so significantly that it has no practical meaning anymore. Thus, the commercial liquid egg white is probably the best option, especially if it generally contains amounts of β-ovomucin as high as were found in these studies. Crude ovomucin was dissolved both by using physical and enzymic methods. Although sonication was the most effective physical method for ovomucin solubilisation, colloid milling seemed to be a very promising alternative. A milk-like, smooth and opaque crude ovomucin suspension was attained by using a colloid mill. The dissolved ovomucin fractions were further tested for bioactive properties, and it was found that three dissolving methods tested produced moderate antiviral activity against Newcastle disease virus, namely colloid milling, enzymatic hydrolysis and a combination of sonicaton and enzymatic hydrolysis. Moreover, trypsin-digested crude ovomucin was found to have moderate antiviral activity against avian influenza virus: both subtype H5 and H7.

Sellulaasit ja niiden käyttö teollisuudessa

Kandidaatintyön kirjallisuuskatsauksessa esitellään selluloosan entsymaattisen hydrolyysin toimintamekanismi ja kerrotaan sellulaasien käytöstä aiheutuvista eduista ja haitoista eri teollisuussovelluksissa.

In vitro protein digestibility of enzymatically pre-treated bean (Phaseolus vulgaris L.) flour using commercial protease and Bacillus sp. protease

The common bean (Phaseolus vulgaris L.) is a staple food in the Brazilian diet and represents the major source of dietary protein and other micronutrients and minerals. Despite the considerable protein concentration in beans, the food is considered of low biological value when compared to animal proteins and other plant protein sources. To improve the availability of protein in beans, enzymatic treatments were performed in four cultivars (ON, OPNS, TAL and VC3). The approach was a completely randomized design with four replicates. We used a 4 × 3 factorial arrangement (four cultivars and three treatments: treatment 1-addition of commercial protease (Trypsin 250, Difco), treatment 2-addition of protease from Bacillus sp., and treatment 3:-control without enzyme addition). The enzyme: substrate ratio was 5% w/w (amount of enzyme per total protein in bean flour). The approach was a completely randomized design with four replicates. A 4 × 3 factorial arrangement (four cultivars and three treatments, the same as those mentioned above) was used. The concentration of total protein (g.100 g-1 of dry matter) in the samples ranged from 16.94 to 18.06%, while the concentration of total phenolics was between 0.78 and 1.12% (g Eq. tannic acid.100 g-1 dry matter). The in vitro protein digestibility of enzymatically untreated bean flour (control) ranged from 47.30 to 56.17% based on the digestibility of casein. Concentrations of P, K, Ca, Mg, and Zn observed in the four cultivars tested were within the average values available in the literature. Treatment 2 with protease from Bacillus sp. induced decreases in the levels of Cu and Mn. The average Fe content increased in all bean flour samples when treated with proteases, reaching a maximum increase of 102% in the TAL flour treated with protease from Bacillus sp. The digestibility of all beans tested was significantly increased (p < 0.05) after the enzyme treatment. The greatest change was observed in the OPNS cultivar treated with protease from Bacillus sp., which increased its digestibility from 54.4% (control treatment) to 81.6%.

Clarification of pineapple juice by microfiltration

In the present work, pineapple juice was first hydrolyzed with a commercial pectinase (Ultrazym 100 G) and then clarified by microfiltration. A tubular polyethersulfone membrane with an average cut-off of 0.3 µm and a total effective filtration area of 0.05 m² was applied. The transmembrane pressures were 1.5 and 3.0 bar, respectively, and the processes was conducted at room temperature. The results showed that the pineapple juice permeate fluxes were of 57.77 L/m²/hours (1.5 bar) and 46.85 L/m²/hours (3.0 bar). Concentration polarization and possibly fouling occurred during the processes. The best clarified juice fluxes were obtained when low transmembrane pressures (1.5 bar) were applied.

Antioxidant activity of black bean (Phaseolus vulgaris L.) protein hydrolysates

Abstract The objective of this work was to study the effect of enzymatic hydrolysis of black bean protein concentrate using different enzymes. Bean proteins were extracted and hydrolyzed over a period of 120 min using the enzymes pepsin or alcalase. The protein hydrolysates’ molecular weight was assayed by electrophoresis and the antioxidant activity was evaluated by the capturing methods of free radicals ABTS●+ and DPPH. Electrophoretic results showed that the bands above 50 kDa disappeared, when the beans protein was subjected to hydrolysis with pepsin. The bean protein hydrolysate obtained by hydrolysis with alcalase enzyme, showed higher antioxidant activity for inhibition of the radical ABTS●+. However, the hydrolysates obtained by hydrolysis with pepsin had higher antioxidant activity for inhibition of the radical DPPH. The use of pepsin and alcalase enzymes, under the same reaction time, produced black bean protein hydrolysates with different molecular weight profiles and superior antioxidant activity than the native bean protein.

Synthese und Charakterisierung neuer Stärkederivate für die klinische Anwendung

Ein neuartiges, mehrstufiges Syntheseverfahren wurde zur Darstellung von unterschiedlichen Stärkederivaten (Ether und Ester) entwickelt, die hinsichtlich ihres Eigenschaftsprofils und ihrer Reinheit für die klinische Anwendung als Blutvolumenersatzmittel geeignet sind. Die Synthesen wurden dahingehend gestaltet, dass Produkte mit einer hohen Regioselektivität resultierten. Dabei konnten sämtliche Reaktionsschritte, die zur Modifikation der ursprünglich eingesetzten Wachsmais- und Kartoffelstärken notwendig waren, in einem homogenen, wäss-rigen System ohne zwischenzeitliche Aufarbeitung in einem Eintopfverfahren durchgeführt werden. Die auf diese Weise bevorzugt synthetisierten Carboxymethylstärken wurden mit NMR-spektroskopischen Methoden und GPC-MALLS strukturell eingehend charakterisiert. Mit eigens entwickelten Enzym-Assays konnten essentielle Informationen über die physiolo-gische Wirksamkeit der verschiedenen Stärkederivate in vitro gewonnen werden. Die Ergebnisse konnten mit Untersuchungen an Humanblut verifiziert werden.