Extrusion of pectin and glycerol with various combinations of orange albedo and starch

Microstructural and mechanical properties of extruded pectin and glycerol films with various combinations of orange albedo and starch were determined by universal mechanical testing (UMT), dynamic mechanical analysis (DMA), optical microscopy (OM) and scanning electron microscopy (SEM). A glass transition and a second order transition attributed to the onset of translational motion of the pectin molecules was observed in all films. Observation by OM suggested that extrusion in the presence of dilute HCl was more effective in disintegrating albedo than either water or dilute citric acid. UMT, DMA and SEM analysis revealed that extruded pectin/albedo/starch/glycerol films provided better mechanical properties than pectin/albedo/glycerol films and were comparable in mechanical properties to extruded pectin/starch/glycerol films.     

Extrusion of pectin/starch blends plasticized with glycerol

The microstructural and thermal dynamic mechanical properties of extruded pectin/starch/glycerol (PSG) edible and biodegradable films were measured by scanning electron microscopy (SEM) and thermal dynamic mechanical analysis (TDMA). SEM revealed that the temperature profile (TP) in the extruder and the amount of water present during extrusion could be used to control the degree to which the starch was gelatinized. TDMA revealed that moisture and TP during extrusion and by inference the amount of starch gelatinization had little effect on the mechanical properties of PSG films. Furthermore, TDMA revealed that PSG films underwent a glass transition commencing at about −50°C and two other thermal transitions above room temperature. Finally, it was concluded that the properties of extruded PSG films were comparable to those cast from solution.     

Enhanced film forming and film properties of amylopectin using micro-fibrillated cellulose

This work describes a novel approach to produce amylopectin films with enhanced properties by the addition of microfibrillated cellulose (MFC). Aqueous dispersions of gelatinized amylopectin, glycerol (0–38 wt%) and MFC (0–10 wt%) were cast at ambient temperature and 50% relative humidity and, after 10 days of storage, the tensile properties were investigated. The structure of the composite films was revealed by optical, atomic force and transmission electron microscopy. The moisture content was determined by thermogravimetry and the temperature-dependent film rigidity was measured by thermal mechanical analysis. Synchrotron simultaneous small- and wide-angle X-ray measurements revealed that the solutions had to be heated to above 85 °C in order to achieve complete gelatinization. Optical microscopy and atomic force microscopy revealed uniformly distributed MFC aggregates in the films, with a length of 10–90 μm and a width spanning from a few hundred nanometers to several microns. Transmission electron microscopy showed that, in addition to aggregates, single MFC microfibrils were also embedded in the amylopectin matrix. It was impossible to cast amylopectin films of sufficient quality with less than 38 wt% glycerol. However, when MFC was added it was possible to produce high quality films even without glycerol. The film without glycerol was stiff and strong but not brittle. It was suggested that this remarkable effect was due to its comparatively high moisture content. Consequently MFC acted both as a “conventional” reinforcement because of its fibrous structure and also indirectly as a plasticiser because its presence led to an increase in film moisture content.     

Two stage extrusion of plasticized pectin/poly(vinyl alcohol) blends

Blends of pectin with starch (high amylose and normal), poly(vinyl alcohol) (PVOH), and glycerol were extruded in a twin screw extruder, pelletized, and then further processed into blown film and extruded sheet using a single screw extruder. The samples were analyzed using tensile measurements, dynamic mechanical analysis, and scanning electron microscopy. PVOH levels of 24% or greater were necessary to successfully make blown film, while extruded sheet could be made at a level of 16% PVOH. Tensile strength and initial modulus of the extruded sheets were slightly higher in the machine direction than in the cross direction, while the reverse was true for elongation to break. For the blown films tensile strength tended to be higher in the transverse direction than in the machine direction, while the reverse was seen for initial modulus. Increased levels of PVOH led to increases in tensile strength and elongation to break, while initial modulus was decreased. Morphology as determined by SEM visually indicated stretching in the transverse direction of the blown films. The second stage extrusion appeared to promote -helix formation in the high amylose starch.     

Effect of polymeric cosolutes on calcium pectinate gelation. Part 2. Dextrans and inulin

In a continuation of the work reported in the preceding paper, the effect of chicory root inulin (M_r≈4.5 kD) and branched dextrans of M_r 67, 464 and 2000 kD on gelation of low methoxy pectin (DE 31; 2.0 wt%; pH≈2.9–3.0) on cooling from 90 to 5 °C in the presence of stoichiometric Ca²⁺ has been characterised by low amplitude oscillatory measurements of G′ and G″. As found for other polymeric cosolutes studied previously (oxidised starch, potato maltodextrin, guar gum and locust bean gum), increasing concentrations of dextran or inulin caused a progressive increase of G′ and G″ in the solution state at 90 °C (attributed to segregative interactions promoting formation of calcium-mediated ‘egg-box’ junctions between pectin chains) and a progressive reduction in final moduli at 5 °C (attributed to excessive association of calcium pectinate into large aggregated bundles), with cooling curves crossing those for calcium pectinate alone at 55 °C. For the dextran samples, the ability to promote initial association of pectin chains at high temperature decreased with increasing molecular weight (i.e. with the smallest molecules having the greatest effect, as was also found for guar gum), but the reduction in final modulus on completion of cooling to 5 °C became more pronounced. By the criterion of the decrease in the change in log G′ during cooling, the three dextran samples studied seem roughly comparable in their overall effectiveness in promoting self-association of pectin, with inulin having a substantially smaller effect. Both materials, however, are less effective than the partially depolymerised starches and galactomannans studied previously. It is tentatively suggested that this may be associated with the flexibility introduced by the presence of three single bonds in the predominant glycosidic linkages of both dextran and inulin.     

Effect of polymeric cosolutes on calcium pectinate gelation. Part 3. Gum arabic and overview

Addition of gum arabic (average M_r≈450 kDa; 0.5–2.0 wt%) to solutions of low methoxy pectin (DE 31; 2.0 wt%; pH≈2.9–3.0) with stoichiometric Ca²⁺ caused massive increases in G′ and G″ in the pre-gel state at 90 °C (attributed to segregative interactions promoting formation of calcium-mediated ‘egg-box’ junctions between pectin chains) but had little effect on the gels formed on cooling to 5 °C. This is in marked contrast to the behaviour of other polymeric cosolutes studied in the investigations reported in the two preceding papers, which caused large reductions in gel moduli (attributed to excessive association of calcium pectinate into large aggregated bundles); the difference is tentatively ascribed to strengthening of the calcium pectinate network by divalent counterions to the uronate residues in gum arabic. When the complication of cation exchange was eliminated by extensive dialysis of gum arabic against 100 mM Na⁺ and use of the final dialysate in preparation of mixtures with calcium pectinate, massive increases in G′ and G″ at high temperature were again observed, but with accompanying reductions in moduli at low temperature, which, at gum arabic concentrations above 1.0 wt%, arose from collapse of the developing calcium pectinate network during cooling. The tentative conclusion from this work, and from the two preceding papers, is that enthalpically unfavourable (segregative) interactions between low methoxy pectin and polymeric cosolutes can be relieved in two ways: (i) Ca²⁺-mediated self-association of pectin into compact ordered assemblies which occupy less of the total volume, and (ii) conformational rearrangement of the cosolute molecules to minimise segmental interactions with pectin; conformational rearrangement is inhibited by chain stiffness and by branching; thus polymeric cosolute molecules of limited flexibility are more effective in promoting self-association of pectin than more flexible molecules of comparable size, and branched molecules are more effective than linear chains of comparable stiffness.     

Spherulitic crystallization of gelatinized maize starch and its fractions

Binary systems of polymers often display spherulitic morphologies after cooling from the melt, but these phenomena have rarely been reported among food polymers of native-size. Here we report the observation of spherulitic and other morphologies in gelatinized maize starch. The morphology could be manipulated by choosing polymer compositions and kinetic regimes. Spherulites (10 μm diameter) formed from gelatinized high-amylose maize starches and purified amylose at cooling rates of order of magnitude 100 °C/min. They were more numerous and exhibited a higher melting point the greater the ratio of amylose to amylopectin. Rapid cooling rates (150–500 °C/min) resulted in a more even distribution of smaller spherulites. Very rapid (liquid nitrogen quench) or slow (0.1–1 °C/min) cooling rates resulted in mixed morphology, as did addition of 15 or 60% (w/w) sucrose to a 10% (w/w) dispersion of high-amylose starch (HAS). Spherulites were observed in aqueous suspensions of high-amylose maize starch between 5 and 30% (w/w). Lower starch concentrations resulted in a broader size distribution and spherulites of more distinct shape. WAXS patterns of B-type were observed. Negatively birefringent spherulites predominated, but positive spherulites were found. The spherulite melting range overlapped with that for amylose–lipid complex. Evidence indicated that micro-phase separation takes place when a holding period at 95 °C follows gelatinization at 180 °C. Despite the high maximum temperature of treatment (180 °C) there was evidence for a memory effect in samples of 30% HAS. Spherulite morphology closely resembled that of native starch granules in very early stages of development.     

Influence of formulation additives on the desiccation tolerance and storage stability of blastospores of the entomopathogenic fungus Paecilomyces fumosoroseus (Deuteromycotina: Hyphomycetes)

Blastospores of the entomopathogenic fungus Paecilomyces fumosoroseus were formulated with 10% lactose/1% bovine serum albumin (BSA) or various compositions of Fantesk™, a starch-oil composite prepared by jet-cooking an aqueous dispersion of starch and oil. Storage stability studies with wet blastospore formulations showed that maximum blastospore survival was achieved during low-temperature storage at -20°C with lactose/BSA formulations or starch-oil formulations supplemented with sucrose, zein protein, and whole milk. Under conditions of wet storage at -20°C, the addition of whole milk to starch-oil formulations significantly improved blastospore stability while the addition of sucrose or zein protein had no effect. In freeze-drying studies, no significant differences were seen in blastospore desiccation tolerance or in stability during storage at either 4 or -20°C when blastospores of P. fumosoroseus were formulated with lactose/BSA or starch-oil formulations with sucrose, zein protein, and whole milk. Freeze-dried blastospore formulations stored at 4°C showed no loss in blastospore viability after 3 months storage and blastospore formulations stored at -20°C showed no loss in viability during the entire 12-month study. For freeze-dried, starch-oil formulations, sucrose was shown to improve blastospore survival during the freeze-drying process. The addition of whole milk to starch-oil formulations significantly improved the stability of freeze-dried blastospores stored at 4°C. Compared to unformulated blastospore suspensions that showed blastospore settling after 30 min, suspensions of blastospores formulated with lactose/BSA or starch-oil composites remained stable for up to 2 h after mixing.     

Pumpkin pectin: gel formation at unusually low concentration

The gel properties of high-methoxy pectin from pumpkins have been investigated to assess the potential of this material as a hard-currency export from the former Soviet Union. Comparison was made with commercial slow-set, medium-set and rapid-set pectins from citrus peel. Gels were formed by cooling pectin solutions (pH 3·0; 60% (w/w) sucrose; 5% (w/w) corn syrup) from 95°C to 25°C, and the time-temperature course of network formation was monitored by small-deformation oscillatory measurements of storage modulus (G′). At concentrations above 1% (w/w) the pumpkin pectin gave weaker gels than the other three samples, but its minimum critical gelling concentration (c₀) was found to be much lower (by at least a factor of five). Compression testing gave similar results, with pumpkin pectin giving useful breaking-stress (‘hardness’) at concentrations down to 0·5% (w/w), about a factor of two lower than for the citrus samples. Its gelation was also less rapid, giving G′ values below those of the other three samples at temperatures down to 60°C, but then setting sharply; this behaviour could be useful in avoiding ‘pregelation’ in commercial processing. The commercial slow-set pectin showed typical ‘weak gel’ properties in the solution state at 95°C, with systematic reduction in gel-like character with increasing ester content in the other samples. The rigidity of the final gels also decreased systematically through the series: rapid-set < medium-set < slow-set. These observations are tentatively ascribed to stable association of unesterified galacturonate chain segments at low pH, where electrostatic repulsion is suppressed.     

Evaluation of different cooling rates, equilibration periods and diluents for effects on deep-freezing, enzyme leakage and fertility of taurine bull spermatozoa

We studied the effects of 2 diluents (Tris and milk), 4 cooling rates (10°C/30°C to 5°C for 1 or 2 h), 2 equilibration periods (0 and 2 h) and their interactions on the freezability, glutamic oxaloacetic transaminase (GOT) leakage and fertility of frozen-thawed semen in 18 ejaculates from 3 Friesian bulls. The means of pre- and post-freezing motility, GOT leakage and fertility rates (52.81% based on follow up of 267 inseminated cows) were significantly (P<0.01) influenced by the bulls, cooling rates & equilibration periods, but not by diluents or the interactions studied. The mean prefreeze motility of spermatozoa following 1 h of cooling from 10°C to 5°C was significantly lower (60.38%) and that after 2 h of cooling from 30°C to 5°C was higher (72.38%) than 2 h of cooling from 10°C to 5°C (66.57%) or 1 h of cooling from 30°C to 5°C (67.96%). The mean post-thaw motility observed following 2 h of prefreeze cooling was, however, significantly greater (45%) than after 1 h of cooling (35%) for both the initial temperatures. Leakage of GOT pre- and post-freezing was significantly less following 2h of cooling from 30°C to 5°C (17.26 and 27.36 μmole/L) than after 1 h of cooling from either 10°C (19.71 and 30.13 μmole/L) or 30°C (18.95 and 29.58 μmole/L) and 2 h of cooling from 10°C to 5°C (21.43 and 34.48 μmole/L). The conception rates for semen frozen at the above cooling rates (66.13, 48.65, 56.67 and 42.25%, respectively) were inverse to GOT leakage. An equilibration period of 2 h over that of 0 h at 5°C adversely affected the prefreeze motility and GOT leakage, but it significantly improved postthaw motility (44.03 vs 35.49%) and fertility rates (57.86 vs 47.24%). These findings suggested that both Trisand milk-based diluents were equally efficacious for cryopreservation of bovine semen, and that slow cooling of semen straws over a period of 2 h from 30°C to 5°C as compared with faster cooling rates or a lower initial temperature (10°C), plus at least 2 h of equilibration time at 5°C were essential for optimal freezability, lower enzyme leakage & higher fertility rates within the tropics.     

Glycerol-plasticized films prepared from starch—poly(vinyl alcohol) mixtures: effect of poly(ethylene-co-acrylic acid)

Equations were obtained from response surface models to show how the ultimate tensile strength (UTS) and percent elongation at break (%E) of solution-cast films vary with relative amounts of starch, poly(vinyl alcohol) (PVA), poly(ethylene-co-acrylic acid) (EAA) and glycerol in the formulation. Equations found from the response surface methodology were used to optimize the relative amounts of the four components with respect to the physical properties of cast films. The model showed that only glycerol content was important to predict the UTS of the films. The model for %E was more complicated, since there was a three-way interaction between EAA, PVA and glycerol. This model also contained two other terms: a two-way interaction evolving glycerol and EAA. and a (PVA)³ term. In general, %E increased as EAA, PVA and glycerol were increased together. However, increased amounts of EAA could decrease %E if EAA was the only component increased. It is believed that EAA forms complexes with both starch and PVA, thereby increasing compatibility of the two polyhydroxy polymers. As %E increases, UTS of the films decreases. All the films produced in this paper were made with starch contents above 50% to insure an optimum film formulation with at least 50% starch. A mixture of 55·6% starch, 2·8% EAA, 28·3% PVA and 13·3% glycerol is believed to be close to the optimum formulation to obtain films having at least 100%E and UTS of 25 MPA, while still maintaining starch concentrations above 50%.     

Postfreeze viability of human renal epithelial carcinoma cells related to phase transformations in ternary solutions

The postfreeze viability of human renal epithelial carcinoma cells frozen in solutions based on a complex physiologic support medium to which additions of NaCl and a cryoprotective agent, either glycerol or dimethyl sulfoxide (DMSO) were made, have been determined by a dye exclusion technique. The support medium consisted of either Eagle's Minimum Essential Medium with Hanks' salts added (MEM) or this same medium supplemented with 20 vol% heat-inactivated fetal calf serum (MEM + FCS). Glycerol was found to be an ineffective cryoprotective agent for these cells, while DMSO was highly effective. Addition of NaCl along with the DMSO further improved the viability of cells frozen at −196 °C. Freezing and thawing rates were found to be important with a slow freezing rate, 2.5 °C/min, and a rapid thawing rate, 240°C/min, yielding the best results.Maximum viability occurred in solutions containing 80 to 95 wt.% (MEM + FCS) with the balance being DMSO and NaCl in the weight ratio of 9:1. In addition to primary ice formation, two nonequilibrium glassy phases were observed during DTA studies of these solutions (10). The exintence of these vitreous states reduces the chances thet cells will be exposed to hypertonic concentrations of salt in the extracellur fluids during freezing-out of primary ice.     

Characterization of orange peel pectin and effect of sugars, -ascorbic acid, ammonium persulfate, salts on viscosity of orange peel pectin solutions

The effects of temperature and concentration on the viscosity of orange peel pectin solutions were examined at five different temperatures between 20 and 60°C and five concentration levels between 2.5–20 kg/m³. The effects of temperature was described by an Arrhenius-type equation. The activation energy for viscous flow was in the range 19.53–27.16 kJ/mol, depending on the concentration. The effect of concentration was described by two types of equation, power-law and exponential. Equations were derived which describes the combined effects of temperature and concentration on the viscosity for two different models in the range of temperatures and concentrations studied. Orange peel pectin was extracted by using HCl (pH 2.5, 90°C, 90 min) ammonium oxalate (0.25%, pH 3.5, 75°C, 90 min) and EDTA (0.5%, 90°C, 90 min) extraction procedures. The best result was obtained with ammonium oxalate extraction in which the pectin content of the final product was 30.12%, although the efficiency among the procedures varied.The average molecular weight was measured by light scattering technique. Magnitudes of intrinsic viscosity and molecular weight of pectins obtained by extraction with HCl, ammonium oxalate and EDTA were 0.262, 0.281, 0.309 m³/kg and 84 500, 91 400, 102 800 kg/kgmol, respectively. The molecular weight dependence of the intrinsic viscosity of the orange peel pectin solutions was expressed by Mark–Houwink–Sakurada equation. The data were fitted to equation as η_i=2.34×10⁻⁵(M_w,ave)^0.8224 which helps to evaluate the average molecular weight of pectin solutions from orange peel with a knowledge of their intrinsic viscosity.     

Structural characterization, degree of esterification and some gelling properties of Krueo Ma Noy (Cissampelos pareira) pectin

Pectins extracted from Krueo Ma Noy (Cissampelos pareira) leaves mainly consisted of galacturonic acid with trace amount of neutral sugars. The dominant structure of Krueo Ma Noy pectin was established as a 1,4-linked -D-galacturonan by a combination of carboxyl reduction and methylation analysis, and confirmed by FT-IR spectroscopy. The degree of esterification of Krueo Ma Noy pectins was 41.7 and 33.7% for crude and dialyzed pectins, respectively. Krueo Ma Noy pectin has an average molecular weight of 55 kDa, radius of gyration of 15.2 nm and intrinsic viscosity of 2.3 dl/g. Krueo Ma Noy pectin exhibited gelling properties in aqueous solutions at 0.5% (w/v) at 5 °C. Gels were formed at concentrations of 1.0% (w/v) and above even at room temperature. The gel strength, melting point, and melting enthalpy of Krueo Ma Noy pectin increased with polysaccharide concentration.     

Isopropyl-Alcohol-Paraffin Methods for Plant Tissues

Two methods using isopropyl alcohol for dehydration prior to paraffin infiltration of plant tissues are reported: (1) a modified Rawlins-Takahashi (1947) schedule in which the preliminary dehydration is effected by concentrating glycerol and (2) isopropyl alcohol as the sole agent for dehydration. With the latter method the fixed tissues are dehydrated successfully in 60%, 85%, and 99% isopropyl alcohol. Paraffin infiltration is accomplished by placing the tissues in isopropyl alcohol over solid paraffin in a vial and heating to 56°-58° C. The tissues settle into the melted paraffin as infiltration progresses. Several changes of pure paraffin are then made, with the last change under reduced pressure. The embedded tissues are trimmed and soaked 2-4 hours at 40° C. in either water or a glycerol, acetic acid, 70% alcohol mixture (10:15:75) to reduce static and insure uniform ribboning during microtomy.     

Gel formation in mixtures of high amylopectin potato starch and potato starch

The effects of starch granules on the rheological behaviour of gels of native potato and high amylopectin potato (HAPP) starches have been studied with small deformation oscillatory rheometry. The influence of granule remnants on the rheological properties of samples treated at 90 °C was evident when compared with samples treated at 140 °C, where no granule remnants were found. The presence of amylose in native potato starch gave to stronger network formation since potato starch gave higher moduli values than HAPP, after both 90 and 140 °C treatments. In addition, amylose may have strengthened the network of HAPP because higher moduli values were obtained when native potato starch was added to the system. The moduli values of the mixtures also increased with increasing polysaccharide concentration in the system, which is due to an increment in the polysaccharide chain contacts and entanglements. Finally, it was found that a mixture of commercial amylose from potato starch and HAPP resulted in lower values of G′ compared to native potato starch. This indicates that the source of amylose is important for the properties in a blend with native amylopectin.     

Influence of cross-linked potato starch treated with POCl3 on DSC, rheological properties and granule size

Differential scanning calorimetry (DSC), rheological measurements and granule size analyses were performed to characterize the influence of phosphorylation substitution levels on the properties of cross-linked potato starch. Phosphorus oxychloride (POCl₃) was used to produce the cross-linked potato starch. The levels of the reagent used for the reaction ranged between 40 and 5000 ppm (dwb). Storage (G′) and loss (G″) moduli were measured for a 5% (w/w) gelatinized starch dispersion stored at 20 °C for 24 h after heating at 85 °C for 30 min. The samples from 80 to 500 ppm were recognized as ‘strong gel'systems, whereas native potato starch showed ‘weak gel'behavior. Steady shear and dynamic viscoelastic properties of gelatinized starch dispersion were compared. Furthermore, granule mean diameter was measured by laser scattering for a 1% (w/w) dispersion heated at 85 °C for 30 min. The granules in the 100 ppm sample swelled to a maximum of about 2.6 times the native starch granule mean diameter.     

Inoculants and Biodegradation of Crude Oil Floating on Marsh Sediments

The efficacy of ten commercial bioremediation products in enhancing the biodegradation of crude oil was investigated in the laboratory at 10 or 30a°C for 90 d with and without supplemental nitrogen and phosphorus. Oil was added to a 1-cm layer of water covering sediments from a salt marsh. The products did not increase the numbers of hydrocarbon-degrading microorganisms in water and sediments but did increase heterotrophic populations at 21 d. Some bioremediation products more than doubled the quantity of hydrocarbons degraded in 45 d at 10°C. At 30°C, no product increased degradation compared to the fertilized control in which 70% of the added hydrocarbons were degraded. Two products increased the percentage of hydrocarbons degraded from 42% to approximately 65% in 45 d at 30°C when supplemental fertilizer was not provided. The hydrocarbon concentration was not significantly reduced between 45 and 90 d for most product treatments at either temperature. At 10°C, products seemed to have the greatest potential for enhancing oil bioremediation compared to the control.     

Effects of lairage temperature and holding time on pig behaviour and on carcass and meat quality

Twenty three groups of about 30 pigs each were kept in an environmentally controlled room in lairage, at temperatures of 20 or 35°C for periods of 0.5 or 3 h, to establish the effects of these parameters on animal behaviour and meat quality. Following initial exploration, 50% of pigs kept at 35°C but only 5% kept at 20°C lay down before the end of the 0.5 h period. Seven percent of pigs fought in both temperature conditions. When held in lairage for 0.5 h there was no difference in meat quality or skin damage at either temperature. When held for 3 h, about 95% of pigs were lying down after 2 h in the pens. Again, the percentage of animals fighting was similar for both temperatures, the number of encounters increasing during the first 30–40 min. The more intense initial fighting within the group held at 35°C resulted in the pigs lying down slightly earlier. Irrespective of the lairage time, the frequency of sexual activity decreased with temperature. The proportion of carcasses with skin damage increased with lairage time due, perhaps, to the longer duration of aggressive encounters. Increased lairage time at 20°C reduced the incidence of PSE meat, but at 35°C the longer lairage time showed no benefit to animal welfare or meat quality.     

Investigations on Nickel Biosorption and its Remobilization

Immobilized preparations of the bacteria (Pseudomonas aeruginosa and Rhodopseudomonas BHU strain 1) and the cyanobacterium ( Anacystis nidulans) exhibited significant Ni adsorption in the order 91%, 72%, 75%, respectively, within 2 h contact with aqueous NiCl₂ (7·05 μg Ni/0·1 mg biomass). The immobilizing agent (Ca-alginate, 1·5%, w/v) absorbed more Ni (43%) than the exopolysaccharide of cyanobacteria, Rivularia sp. (40%) or Aphanothece sp. (30%). Ni remobilization from different adsorbed systems was maximum (84%) for Ca(NO₃)₂ over NaCl (4·3%) at equimolar concentrations (12 m , each). Extracts from forest soil (organic C, 2-3%) were more effective in Ni remobilization (22·65%) than similar preparations from garden soil (18%) with organic C in the range of 0·98-1·1%.