Oxidized Potato Starch Research Articles

Development of oxidised and heat–moisture treated potato starch film

This study investigated the effects of sodium hypochlorite oxidation and a heat–moisture treatment of potato starch on the physicochemical, pasting and textural properties of potato starches in addition to the water vapour permeability (WVP) and mechanical properties of potato starch films produced from these starches. The carbonyl contents, carboxyl contents, swelling power, solubility, pasting properties and gel texture of the native, oxidised and heat–moisture treated (HMT) starches were evaluated. The films made of native, oxidised and HMT starches were characterised by thickness, water solubility, colour, opacity, mechanical properties and WVP. The oxidised and HMT starches had lower viscosity and swelling power compared to the native starch. The films produced from oxidised potato starch had decreased solubility, elongation and WVP values in addition to increased tensile strength compared to the native starch films. The HMT starch increased the tensile strength and WVP of the starch films compared to the native starch.

Effects of Saccharose Substitutes on Physicochemical Properties and Free Radical Generation in Oxidized Potato Starch

This study aimed at investigating the effects of saccharose and its substitutes (sorbitol, acesulphame, aspartame) added to potato starch oxidized with sodium chlorate (I) on the physicochemical properties of starch and generation of free radicals at both 150 and 230°C. Oxidized starch with saccharose and its substitutes were analyzed by thermodynamic characterization of pasting, rheological properties, and susceptibility to degradation of 2% pastes. Moreover, a number of generated thermally free radicals in investigated samples was determined by quantitative electron paramagnetic resonance spectroscopy measurements. Saccharose and sorbitol increased considerably the onset temperature of transition (T0) and the peak temperature of transistion (Tp) as determined by differential scanning calorimetry. Among the sweeteners, only aspartame influenced the characteristic viscosities of the starch-sweetener-water systems, reducing the thermal stability of the obtained pastes. Acesulphame K and aspartame caused the largest increase in the susceptibility to retrogradation of 2% pastes of oxidized potato starch. In the presence of sorbitol, the number of radicals generated thermally in starch decreased. This effect, found by quantitative electron paramagnetic resonance spectroscopy measurements, indicates effective interaction of hydroxyl groups of the sorbitol molecule with starch matrix, leading to the stabilization of the starch structure.

Optimization of Preparation Process of Oxidized Potato Starch Acetate by Response Surface Methodology

The response surface methodology(RSM) was used to optimize the preparation conditions of oxidized potato starch acetate.On the basis of one-factor-at-a-time experiments,a 29-run Box-Behnken experimental design involving 4 variables at 3 levels was used for mathematical modeling of substitution degree(SD) with respect to NaClO amount,acetic anhydride amount,pH and reaction time.The optimal reaction conditions for improved SD were NaClO amount 1.805%,starch/acetic anhydride ratio 5:1(m/m),pH 8.06 and reaction time 1.5 h,resulting in an SD of 0.0975.

Influence of copper catalyst on the mechanism of carbohydrate radicals generation in oxidized potato starch

Using EPR technique it was stated that copper ions introduced into potato starch, as catalyst of its oxidation with H2O2, was the active reagent in the generation of stable carbohydrate radicals. EPR parameters indicated that radicals, thermally generated in starch oxidized with H2O2 in the presence of Cu(II), were formed by abstraction of hydrogen atom from C(5) atom of glucose unit. It was found that generation of radicals was correlated with the reduction of Cu(II) to Cu(I) and formation of glucose-copper complexes. The reduction of copper occurring during thermal treatment was confirmed by colour parameters (a* increased from 0.96 for native starch to 9.10 for starch oxidized with H2O2 in the presence of copper catalyst). In the starch not containing copper (native and oxidized with H2O2) different types of radicals were generated. The mechanism of their creation consisted in abstraction of hydrogen from C(6), C(1) and C(3) carbon atoms. Formation of radicals upon dehydration of starch was also considered. Generation of radicals was correlated with the amount of copper catalyst used to oxidation process (0.1–0.3%) and with the number of carboxyl groups which was equal to 0.12% in starch oxidized with H2O2 and increased to 0.22% in starch oxidized in the presence of copper catalyst (0.3% of Cu). The stability of carbohydrate radicals was influenced mainly by distortion of the starch structure, as well as the presence of copper ions. Increase of the content of carbonyl groups upon oxidation (to 0.13% for starch oxidized with H2O2 and 1.31% for starch oxidized with H2O2 in the presence 0.3% copper catalyst) pointed to the progressive degradation of starch structure during oxidation.

Mobility of lysozyme inside oxidized starch polymer microgels

The aim of this paper is to determine the mobility of protein molecules inside oxidized potato starch polymer (OPSP) microgel particles (spherical, 10–20 µm in diameter). This provides relevant information for controlled uptake and release applications of such systems. The mobility of Alexa-488 labelled lysozyme inside the microgel is measured by fluorescence recovery after photobleaching (FRAP) in combination with confocal laser scanning microscopy (CLSM). CLSM images show that the protein molecules distribute quite homogeneously over the microgel particles. By fitting the FRAP data with a model based on exchange between bleached and unbleached protein molecules inside the gel, we identified several protein fractions of different mobility. Increasing the salt concentration (NaCl) or the pH causes a shift in the distribution towards the more mobile fractions. This is consistent with earlier uptake and release measurements, which showed that the binding affinity decreases with increasing salt concentration and pH. At low protein concentrations, at which the microgel is not saturated with protein, the mobility of the bound protein molecules is more restricted than at protein concentrations where the uptake is complete. This is attributed to binding of the protein molecules to multiple binding sites. The model explains reasonably the mechanism of protein mobility inside the microgel, indicating that embedded ingredients with charge properties comparable to those of lysozyme can be protected at low salt concentration and low pH. Increasing the salt concentration or the pH triggers the release.

Binding of amino acids to hypochlorite‐oxidized potato starch

AbstractNovel starch derivatives were prepared by derivatization of oxidized potato starch with amino acids in aqueous suspension. Potato starch was oxidized using sodium hypochlorite and then reacted with amino acids under mildly alkaline conditions. By analysis of increased nitrogen content and by means of confocal laser scanning microscopy, efficient binding of positively charged amino acids to oxidized starch molecules was confirmed. A degree of substitution (DS) of up to 0.015 was obtained using oxidized starch (degree of oxidation (DO) of up to 1.0%) and positively charged amino acids (2–5%, dry starch basis) at reaction conditions of starch/water ratio of 1:2–2.5, pH 10, 40°C, 30–60 min. The DS was positively correlated with the DO of the starch. Derivatization of oxidized starch using amino acids generally enhanced the influence of oxidation on starch pasting characteristics, perhaps showing interesting functional properties and potential industrial application.

Lysozyme Uptake by Oxidized Starch Polymer Microgels

With the aim of determining suitable conditions for uptake and release of globular proteins on microgels, we studied the interaction between phosphated, highly cross-linked, negatively charged oxidized potato starch polymer (OPSP) microgel particles and lysozyme from hen eggs. Our microgel shows a typical protein-induced deswelling behavior for charged microgels. The protein distributes rather homogenously through the microgel. We found that at low salt concentration the saturation protein uptake Gammasat increases with increasing pH. This is because the binding capacity is mainly determined by charge compensation: with increasing pH, the (positive) charge on the lysozyme molecules decreases, while the (negative) charge of the microgel particles increases. Therefore, more protein molecules are needed to compensate for the charge on the gel and the binding capacity increases. The protein binding affinity, however, decreases sharply with increasing pH, presumably because this affinity is mainly sensitive to the lysozyme charge density. At high pH the binding affinity is relatively low, and by adding salt, the protein can easily be released from the gel. This leads to a maximum in the curves of Gammasat versus pH, and this maximum shifts to lower pH values with increasing ionic strength. We conclude that, for protein uptake and release applications, the present system works best around pH 5 due to a sufficiently high binding affinity and a sufficiently high binding capacity.

Preparation and characteristics of oxidized potato starch films

Starch films were developed from oxidized potato starch (OPS) with glycerol as a plasticizer at different contents. The OPS films were transparent and flexible. The mechanical properties of these films were measured, and the results indicated that the film with 19.4% glycerol exhibited the desirable mechanical properties. X-ray diffraction study showed that the increase of glycerol content led to a decrease in the crystallinity for OPS films, and storage conditions such as storage time, storage temperature and relative humidity also had certain effects on the retrogradation of starch owing to re-crystallization. Anti-leakage, anti-crosslinking, and stability in acid or alkali solutions of the OPS films were also studied, and the results indicated that the OPS films had excellent anti-leakage ability for vegetable oil, good anti-crosslinking ability in saturated formaldehyde vapor, and good stability in acid aqueous medium, but poor stability in alkali aqueous medium.

Improvement of paper strength via surface application of sugar beet pectin

AbstractThe influence of surface-applied original and enzymatically-modified sugar beet pectin on strength properties of fluting, coating base paper, and core board was investigated. The effect was compared with the application of commercial strength-increasing agents. With increasing the polymer uptake, measured strength of paper increased. Original sugar beet pectin increased the strength properties of papers, at the same uptake of polymer, to a higher extent than oxidised potato starch or modified grain flour, while the effect of enzymatically-modified sugar beet pectin was the lowest. For the same increase of paper strength, a several times higher uptake of enzymatically-modified sugar beet pectin was required when compared with the original pectin, oxidised potato starch, or modified grain flour.

Gel texture and chain structure of amylomaltase-modified starches compared to gelatin

Amylomaltase (AM) (4- α- d-glucanotransferase; E.C. 2.4.1.25) from Thermus thermophilus was used to modify starches from various botanical sources including potato, high amylose potato (HAP), maize, waxy maize, wheat and pea, as well as a chemical oxidized potato starch (Gelamyl 120). Amylopectin chain length distribution, textural properties of gels and molecular weight of 51 enzyme and 7 non-enzyme-modified starches (parent samples) were analyzed. Textural data were compared with the textural properties of gelatin gels. Modifying starch with AM caused broadening of the amylopectin chain length distribution, creating a unimodal distribution. The increase in longer chains was supposedly a combined effect of amylose to amylopectin chain transfer and transfer of cluster units within the amylopectin molecules. Exploratory principal component analysis (PCA) data analysis revealed that the data were composed of two components explaining 94.2% of the total variation. Parent starches formed a cluster separated from that of the AM-modified starches. Extended AM treatments reduced the apparent molecular weight and the gel texture without changing the amylopectin chain length distribution. However, the gel texture was typically increased as compared to the parent starch. AM-modified HAP gels were about twice as hard as gelatin gels at identical concentration, whereas gels of pea starch were comparable to gelatin gels. Modifying Gelamyl 120 and waxy maize with AM did not change the textural properties. Branching enzyme (BE) (1,4-α- d-glucan branching enzyme; EC 2.4.1.18) from Rhodothermus obamensis was used in just one modification and in combination with AM. The combined AM/BE modification of pea starch resulted in starches with shorter amylopectin chains and pastes unable to form gel network even at concentration as high as 12.0% (w/w). The PCA model of all gel texture data gave suggestive evidence for starch structural features being important for generating a gelatin-like texture.

Physicochemical properties of cassava, potato and jicama starches oxidised with organic acids

AbstractThe oxidising effects of organic (acetic, citric and lactic) acids on the physicochemical properties of starches from cassava, potato and jicama were investigated. Cassava starch oxidised with lactic and citric acids had the highest carbonyl contents (5.43 and 5.84 g kg−1 respectively), while oxidised potato starch had the highest carboxyl contents. Oxidised jicama starch showed the lowest carbonyl and carboxyl contents. Oxidation increased the maximum viscosity of cassava starch (from 426.61 to 670.11 relative viscosity units (RVU)) and jicama starch (from 160.17 to 561.50 RVU) but decreased that of potato starch (from 669.44 to 206.92 RVU). When carbonyl and carboxyl groups were incorporated into jicama starch granules, the resistance of these granules to stirring at constant temperature (holding) increased, as did their final and retrogradation viscosities. However, the behaviour of oxidised cassava and potato starches, as indicated by a Rapid Visco Analyser, was different. The highest values of endotherm enlargement were found for native and oxidised jicama starch, while the lowest values were found for native and oxidised cassava starch. Native and oxidised potato starch had the highest enthalpy values (14.30–18.30 J g−1), while jicama starch had the lowest (9.50–11.9 J g−1). The high intrinsic viscosity of native potato starch was attributed to B‐type starch with a longer‐than‐average amylopectin chain length and a lower degree of crystallinity. Oxidised granules showed little erosion in the form of grooves; on the contrary, oxidation left the grains with a very smooth surface. Copyright © 2007 Society of Chemical Industry

Biodegradacja folii z polietylenu modyfikowanego skrobia. Badanie zmian struktury nadczasteczkowej polietylenu

Decompositions of the films made of low-density polyethylene (PE-LD) modified with oxidized potato starch (PESZ) or corn starch (PESK), after 6, 12 or 16 months (e.g. PESZ-6, PESZ-12 etc.) of mixed bacteria action have been investigated. Bacteria population consisted of Bacillus type bacteria, Actinomycetales and mildew fungi isolated from the soil. The results of the film biodegradation process were estimated on the basis of a degree of microorganisms' growth (Table 1), surface changes observed using a microscope (Figs. 1 and 2) as well as structural changes determined by WAXS (Figs. 3 and 4, Table 2) or SAXS (Figs. 5-7). Significant adhesion of microorganisms colonies to the film surface as well as morphology changes and numerous losses of starch grains were found after 16 months of biodegradation. There were also found the changes in polyethylene supermolecular structure, manifested as a decrease in PE lamellar structure long period dimensions (Table 3). The demonstrated effect of biodegradation did not depend on the kind of a starch applied. Biodegradation does not influence the ratio of crystalline and amorphic phases in the polymer.

The substitution pattern in cationised and oxidised potato starch granules

The distribution pattern of substituents within the granules and the components of two cationised and two oxidised potato starches was studied. The level of crystallinity in wet-cationised (WC) and hypochlorite oxidised (HO) starch granules was similar to that of native starch granules but lower in dry-cationised (DC) and peroxide oxidised (PO) granules. However, the melting temperature of DC granules remained similar to native granules but was decreased in the other samples. With all modified starches, the initial rate of acid hydrolysis (lintnerisation) was increased compared to native granules. The degree of substitution decreased only slightly in WC granules after the lintnerisation, whereas virtually all the substituted glucosyl units in DC starch were hydrolysed already at initial stages. The decrease of substituents in the HO and PO starches was intermediate. The starches were partly resistant to the action of isoamylase and the successive β-amylolysis, suggesting that substituents were found both close to the branches and near the nonreducing ends in the amylopectin component. It is suggested that the DC starch was preferentially cationised at the surface of the granules, whereas WC and oxidised starches were modified throughout the granules.

Structural characterization of oxidized potato starch

Sodium hypochlorite oxidized (HO) and hydrogen peroxide oxidized (PO) potato starches were fractionated on an ion-exchange chromatography column of DEAE-Sepharose. Bound dextrins represented the major fraction and possessed larger d.p.-values than the minor fraction of unbound dextrins. The HO- and PO-starches were also debranched prior to separation on the ion-exchanger. The proportion of bound chains was much larger in the HO-starch. In both starches only 63% of the bound chains were resistant to beta-amylolysis, suggesting that the non-resistant chains possessed substitutions at the reducing end. The relative molar concentration of modified chains were 34 and 20% in the HO- and PO-starch, respectively. 13C NMR spectra of fractions obtained from the HO-starch showed that carboxylic groups were concentrated on the bound chains.

Flocculation in kaolin suspensions induced by modified starches 2. Oxidized and hydrophobically modified oxidized starch in comparison with poly(vinyl alcohol) and carboxymethylcellulose

Turbidity fluctuations in flowing kaolin suspensions (1% w/w) were studied by a fibre-optical sensor technique. From these measurements, a flocculation index (F) was calculated for each of the suspensions. A high value of F indicates a high degree of flocculation. Addition of an oxidized potato starch resulted in substantial flocculation of the suspension, as was the case when the kaolin was pre-treated with sodium polyacrylate (NaPA). The flocculation behaviour of the NaPA-treated suspensions indicated that depletion flocculation is a very likely flocculation mechanism. When a hydrophobically modified oxidized potato starch was added to the NaPA-treated suspension, no flocculation occurred and no adsorption of the hydrophobically modified starch on the kaolin particles could be detected. These results are compared with those obtained when poly(vinyl alcohol) and sodium carboxymethylcellulose were used in place of the starch. The influence on flocculation of the ionic strength and pre-treatment with sodium polyacrylate was investigated.

Microstructural and Physicochemical Properties of Oxidized Potato Starch for Paper Coating

AbstractHeat‐induced structural changes were examined for a series of potato starches differing in degree of oxidation and prepared as 25 and 35% dispersions. The molecular weight of amylopectin decreased markedly with the degree of oxidation. Microstructural studies revealed that all oxidized potato starch dispersions heated to 90deg;C contained whole granules. The least oxidized potato starch (Raisamyl 316) paste contained large numbers of swollen granules filled with dissolved amylose. In the more oxidized potato starch dispersions, both amylopectin and amylose were solubilized within the granule. Mixing of the amylose and amylopectin occurred and amylose‐ and amylopectin‐rich domains could be seen inside the granule. At 35% concentration all starches studied formed a gel during cooling (from 90 to 30deg;C). The lower the degree of oxidation, the higher the gelling temperature. Raisamyl 310 formed the firmest gel. The gel formation of most oxidized potato starches was weak. Raising the heating temperature from 90 to 120deg;C, in combination with shearing, delayed the gelation.

Chemical Characterization of Bromine Oxidized Potato Starch

AbstractPotato starch was oxidized with a neutral aqueous bromine solution at seven different levels of molar ratios of bromine/starch (1/40–5/1). The molecular weight distribution of the products obtained was analysed by gel permeation chromatography on two different agarose gels, Sepharose CL‐2B and Superose 6. A gradually increased fragmentation of the molecules with increased oxidation level was noticed. Some of the modified samples were debranched and the products obtained were analysed by gel permeation chromatography. For comparison amylose and waxy maize starch were also treated at the 1/20 and 1/5 molar ratios. The results indicate that the amylose is more easily degraded to small fragments than amylopectin during the oxidation process. An enzymatic starch analysis method was applied on the oxidized samples. This method was found suitable for estimating the total content of introduced keto and carboxylic groups into the modified product.

Physical Characterization of Bromine Oxidised Potato Starch

AbstractNative potato starch and potato starch oxidised with bromine at different concentrations were studied. A successive decrease of the gelatinisation enthalpy and a downward shift in the gelatinisation temperature were observed by the use of differential scanning calorimetry. When the oxidation was followed by a reduction step, those effects were accentuated. The mean molecular weight of the starch diminshed as the concentration of bromine oxidant was increased. In accordance with this, the viscosity of water solutions of corresponding samples successively decreased. However, when samples were reduced after the oxidation step, an increase in the viscosity was observed. A microscopic investigation showed that the granule structure was lost already at the lowest level of oxidation.