Polymer-Solvent Interactions in Modified Starches Pastes-Electrokinetic, Dynamic Light Scattering, Rheological and Low Field Nuclear Magnetic Resonance Approach.

Starch paste is a very complex dispersion that cannot be clearly classified as a solution, colloid or suspension and many factors affects its properties. As these ambiguities constitute a barrier to technological development, the aim of this study was to investigate the interaction of starch macromolecules with water by analysing the results of rheological properties, low field nuclear magnetic resonance (LF NMR), dynamic light scattering (DLS) and ζ potential analyses. Starch pastes with a concentration of 1%, prepared with distilled water and buffered to pH values of 2.5, 7.0 and 9.5 were analysed. It was proved that the pH buffering substantially decreased the values of consistency index but the pH value itself was not significant. LF NMR studies indicated that the dissolution of starch in water resulted in a reduction in spin-lattice as well as spin-spin relaxation times. Moreover, changes in relaxation times followed the patterns observed in rheological studies. Electrokinetic and DLS analyses showed that potential values are primarily influenced by the properties of the starches themselves and, to a lesser extent, by the environmental conditions. The conducted research also showed complementarity and, to some extent, substitutability of the applied research methods as well as exclusion chromatography (a method not used in this work).

Bioactive Substances of Potato Juice Reveal Synergy in Cytotoxic Activity against Cancer Cells of Digestive System Studied In Vitro.

More and more literature data indicate the health-promoting effect of potato juice (PJ). However, to date, it has not been precisely explained which of the many compounds present in PJ exhibit biological activity. The work aimed to establish the antiproliferative effect of gastrointestinal digested PJ and the products of its processing. Fresh PJs derived from three edible potato varieties, industrial side stream resulting from starch production, partially deproteinized PJ derived from feed protein production line, and three different potato protein preparations subjected to digestion in the artificial gastrointestinal tract were used in this study. The cytotoxic potential of glycoalkaloids (GAs), phenolic acids, digested PJ, and products of PJ processing was determined in human normal and cancer cells derived from the digestive system. The results showed that GAs exhibit concentration-dependent cytotoxicity against all analyzed cell lines. In contrast, phenolic acids (caffeic, ferulic, and chlorogenic acid) do not show cytotoxicity in the applied cell lines. A correlation between cytotoxic potency and GAs content was found in all PJ products studied. The most potent effects were observed under treatment with deproteinized PJ, a product of industrial processing of PJ, distinguished by the highest effective activity among the fresh juice products studied. Moreover, this preparation revealed a favorable cytotoxicity ratio towards cancer cells compared to normal cells. Statistical analysis of the obtained results showed the synergistic effect of other bioactive substances contained in PJ and its products, which may be crucial in further research on the possibility of using PJ as a source of compounds of therapeutic importance.

Membrane Filtration-Assisted Enzymatic Hydrolysis Affects the Biological Activity of Potato Juice.

The results of recently published studies indicate that potato juice is characterized by interesting biological activity that can be particularly useful in the case of gastrointestinal symptoms. Moreover, the studies also described the high nutritional value of its proteins. This article is a report on the impact of the enzymatic hydrolysis of proteins combined with membrane filtration. The obtained potato juice protein hydrolysate (PJPH) and its concentrate (cPJPH) were characterized in terms of their nutritional value and biological activity. The amino acid profile and scoring, the content of mineral compounds, and the antioxidant and in vitro cytotoxic activity were assessed. The study proved that the antioxidant activity of PJPH is higher than that of fresh potato juice, and the cytotoxicity against human gastric carcinoma cell line (Hs 746T), human colon cancer cell line (Caco-2), human colorectal adenocarcinoma cell line (HT-29), and human normal colon mucosa cell line (CCD 841 CoN) showed biological activity specifically targeted against cancer cells. Therefore, it can be concluded that the membrane filtration-assisted enzymatic hydrolysis of potato juice proteins may increase their biological activity and allow for potato juice to be used in the production of medicinal preparations.

Light Microscopy as a Tool to Evaluate the Functionality of Starch in Food.

Light microscopy (LM) is commonly used in the study of biological materials to determine the morphology of cells and tissues. The potential of this technique for studying the structure of food products is also recognized but less known. Especially rare are information regarding LM studies of the supramolecular structure of starch. The aim of the work was to fill this gap by providing data on the possibilities for application of LM in starch studies. It was shown that in spite of an enormous progress in the development of microscopic techniques, including both increase of resolution and improvement of image analysis methods, light microscopy still has a huge potential for starch studies. The advantage of LM over other microscopic techniques is the possibility of differentiating between amylose and amylopectin by iodine staining. That makes LM especially useful in the analysis of the process of gelatinization of starch, the extent of molecular dispersion of its macromolecules, and the changes in its structure caused by modification. Moreover, it can be particularly useful for studying the changes in the supramolecular structure of starch in a food product matrix, providing more information than scanning electron microscopy (SEM)-the most common technique used for these purposes.

The Nutritional Value and Biological Activity of Concentrated Protein Fraction of Potato Juice.

Potato protein is recognized as one of the most valuable nonanimal proteins due to the high content of essential amino acids. So far, it has not been used in human nutrition on a large scale due to technological limitations regarding its acquisition. In this study, the protein fraction of potato juice was concentrated with the use of membrane separation. The obtained potato juice protein concentrate (PJPC) was characterized in terms of nutritional value and biological activity, and the amino acid composition, mineral content, and antioxidant properties were determined. Moreover, in vitro cytotoxic activity against cancer cells of the gastrointestinal tract was investigated. The results of the present study indicate that PJPC is an excellent source of lysine and threonine, while leucine is its limiting amino acid, with an amino acid score (AAS) of 65%. Moreover, PJPC contains substantial amounts of Fe, Mn, K, and Cu. As demonstrated experimentally, PJPC is also characterized by higher antioxidant potential than potato itself. Biological activity, however, is not limited to antioxidant activity alone. Cytotoxicity studies using a gastric cancer cell line (Hs 746T), a colon cancer cell line (HT-29), and human colon normal cells (CCD 841 CoN) proved that PJPC is characterized by selective activity against cancer cells. It can thus be concluded that the developed method of producing protein concentrate from potato juice affords a product with moderate nutritional value and interesting biological activity.

Effect of Thermal Processing on Antioxidant Activity and Cytotoxicity of Waste Potato Juice.

Potato juice (PJ), commonly considered a burdensome waste, is rich in various compounds with bioactive properties. It has long been considered a remedy for gastric problems in traditional folk medicine. If valorization of PJ through implementation in the production of functional foods is to be considered, stabilization methods must be developed to allow long-term storage of this seasonal product. It is important that such methods are chosen with regard to their effect on the bioactive value of the obtained product. In this study, the impact of four stabilization methods on the antioxidant and cytotoxic activities of PJ was investigated. Elevated temperatures were used in thermal deproteinization used to obtain DPJW (deproteinated potato juice water) and spray-drying of FPJ (fresh potato juice) that resulted in SDPJ. Freeze drying and cryoconcentration were the low temperature processing methods that yielded PJL (potato juice lyophilisate) and CPJ (cryocorncentrated potato juice), respectively. All processed materials were characterized chemically and compared with raw materials in terms of phenolic compounds content, antioxidant activity as well as cytotoxicity to human tumor cells isolated from the gastric mucosa (Hs476T cell line), colon (Caco-2 and HT-29 cell lines), and normal cells isolated from the small intestine and colon epithelium (IEC-6 and NCM460 cell lines). It was stated that high-temperature processes - thermal deproteinization and spray-drying - yielded products with increased antioxidant potential (TEAC) that also showed increased cytotoxic activity towards intestinal cancer cells. At the same time the cytotoxicity towards normal cells remained on par with that of fresh PJ (IEC-6 cells) or decreased (NCM460 cells). Thermal deproteinization significantly decreased the content of glycoalcaloids in the juice, while spray drying did not have such an effect. The two low-temperature processes investigated - cryoconcentration and freeze drying - did not affect the PJ cytotoxic activity towards any of the cell lines used in the tests, whereas they did affect the antioxidant properties and glycoalcaloids content of PJ.

Egg Yolk Extracts as Potential Liposomes Shell Material: Composition Compared with Vesicles Characteristics.

Our aim was to propose simple extraction process to obtain phospholipids along with yolk-derived vitamins and fats. Five extracts marked as ethanol/acetone, methanol-chloroform/acetone, hot ethanol, hexane, and cold ethanol were developed and compared. Extracts' compositions were analyzed in terms of phospholipid, polar and nonpolar fraction, cholesterol, carotenoids, and tocopherols content. Further, liposomes prepared from extracts were characterized. The highest extraction efficiency was achieved by a one-step hexane procedure. However, that sample, in contrast to the other four extracts, revealed distinctively lower permeability when used for liposomes membrane formation. Principal component analysis proved that major components contents were decisive for liposomes membranes permeability, whereas minor constituents' content controlled zeta potential and Z-average size. PRACTICAL APPLICATION: Liposomes are nanocarriers widely used in pharmaceutical industry. Due to intravenous route of administration, they have to be produced from phospholipids of very fine purity. On the other hand, there is increasing interest in nanoencapsulation of labile, bioactive substances for manufacturing of health promoting food. Unfortunately, high-price pure phospholipids are prohibitive for food applications. The use of raw material obtained by simple extraction procedure instead of highly purified phospholipids could be an attractive alternative for food industry.

Spray-Dried Potato Juice as a Potential Functional Food Component with Gastrointestinal Protective Effects.

BACKGROUND: Peptic ulcer disease, including its complications and functional dyspepsia, are prevalent gastrointestinal diseases, etiopathogenesis of which is associated with mucosal inflammation. Research into new therapeutics capable of preventing or curing gastrointestinal mucosal damage has been steadily developing over past decades. This study was undertaken to evaluate whether a spray-dried preparation of potato juice is applicable for treating and preventing gastrointestinal mucosal damage. METHODS: We assessed potential protective effects of spray-dried potato juice (SDPJ) against gut inflammation in the co-culture Caco-2/RAW264.7 system, as well as a gastroprotective activity in a rat model of gastric ulceration. RESULTS: The obtained results indicated that SDPJ down-regulates lipopolysaccharide (LPS)-induced mRNA expression and protein production of proinflammatory cytokines IL-6 and TNF-α in the co-culture model. Moreover, SDPJ provided dose-dependent protection against LPS-induced disruption of intestinal barrier integrity. In rats, five-day pretreatment with SDPJ in doses of 200 mg/kg and 500 mg/kg suppressed HCl/ethanol-induced TNF-α expression in gastric mucosa by 52% and 35%, respectively. In addition, the pretreatment with the lower dose of SDPJ reduced the incidence of ulcers (by 34%) expressed as ulcer index. CONCLUSION: The spray-dried potato juice appears to be an attractive candidate for ameliorating inflammation-related diseases of the gastrointestinal tract.

The effect of high hydrostatic pressure treatment on the molecular structure of starches with different amylose content.

The effect of high hydrostatic pressure processing (650MPa/9min) on molecular mass distribution, and hydrodynamic and structural parameters of amylose (maize, sorghum, Hylon VII) and amylopectin (waxy maize, amaranth) starches was studied. The starches were characterized by high-performance size-exclusion chromatography (HPSEC) equipped with static light scattering and refractive index detectors and by Fourier Transform Infrared (FTIR) spectroscopy. Significant changes were observed in molecular mass distribution of pressurized waxy maize starch. Changes in branches/branch frequency, intrinsic viscosity, and radius of gyration were observed for all treated starches. The combination of SEC and FTIR data showed that α-1,6-glycosidic bonds are more frequently split in pressurized amaranth, Hylon VII, and waxy maize starch, while in sorghum and maize starches, the α-1,4 bonds are most commonly split. Our results show that the structural changes found for pressurized starches were more strongly determined by the starch origin than by the processing applied.

Lipid nanoparticles assessment by flow cytometry.

BACKGROUND: Liposomes are promising carriers for drugs and bioactive compounds. Size and structure are their crucial parameters. Thus, it is essential to assess individual vesicles as prepared. Currently available techniques fail to measure liposome's size and structure simultaneously, with a high throughput. To solve this problem, we have developed a novel, flow cytometric method quantifying liposomes. METHODS: Firstly, the following fluorescent staining combinations were tested: DiD/TO, Rh123/DiD, Syto9/DiD. Further, chosen fluorochromes were used to compare three populations of vesicles: raw (R), obtained by thin film hydration and extruded ones (populations E10 and E21). Dynamic light scattering (DLS) was used for determination of average diameter and size distribution of nanocarriers. Structural differences between the raw and the extruded liposomes, as well as additional information concerning vesicles size were acquired employing atomic force microscopy (AFM). RESULTS: DLS analysis indicated that, three distinct populations of vesicles were obtained. Liposomes were characterized by mean diameter of 323nm, 220nm and 170nm for population R, E10 and E21 respectively. All the populations were stable and revealed zeta potential of -29mV. AFM confirmed that raw and extruded liposomes were differed in structure. CONCLUSIONS AND GENERAL SIGNIFICANCE: DiD/TO was the optimal fluorochrome combination that enabled to resolve distinctly the sub-populations of liposomes. Results obtained by flow cytometry were in a good agreement with those from DLS and AFM. It was proved that, flow cytometry, when proper fluorescent dyes are used, is an adequate method for liposomes assessment. The proposed method enables fast and reliable analysis of liposomes in their native environment.

Molecular and Supermolecular Structure of Commercial Pyrodextrins.

Size exclusion chromatography with triple detection as well as infrared spectroscopy studies of commercially available pyrodextrins proved that these molecules are characterized not only by significantly lower molecular mass, in comparison to that of native starch, but also by increased branching. Therefore, pyrodextrins adopt a very compact structure in solution and show Newtonian behavior under shear in spite of their molecular masses of tens of thousands Daltons. The results also indicate that 50% reduction of digestibility of pyrodextrins is, to a minor extent, caused by formation of low-molecular color compounds containing carbonyl functional groups. The main reason is, as postulated in the literature, transglycosidation that leads to decreased occurrence of α-1,4-glycoside bonds in the molecular structure. In the process of dextrinization starch also undergoes changes in supermolecular structure, which, however, have no influence on digestibility. Likewise, the effect of formation of low-molecular colorful compounds containing carbonyl groups is not crucial.

Pasta Fortified with Potato Juice: Structure, Quality, and Consumer Acceptance.

The potential of potato juice in relieving gastrointestinal disorders has already been proven. Work continues on implementation of this active component into products that are widely consumed. In this article, results of an attempt to fortify pasta with potato juice are presented and discussed. Fortification is performed using fresh and dried juice. The influence of the addition on culinary properties of the final product, such as cooking weight and cooking loss, as well as microstructure, color, texture, and consumer acceptance were evaluated. It was found that potato juice can be used for fortification of pasta both in its fresh and dried forms, however the effects on different responses depend on the potato juice form used. The addition of potato juice influenced the color of the product reducing its lightness and shifting color balances from green to red, yellow color saturation was decreased as well. Changes in color were more significant in the case of fresh juice addition. The firmness and microstructure of pasta was also influenced. The surface microstructure of pasta containing fresh potato juice was different from that of the other 2 products being a likely explanation of the lower cooking loss observed in its case. In contrast, the consistency of dough was strengthened by addition of dried potato juice. Principal components analysis indicated that the color change had the most pronounced effect on consumer acceptance. Other physicochemical changes were slightly less significant. Nevertheless, sensory evaluation proved that functional pasta produced with fresh potato juice finds consumer acceptance comparable with that of classic pasta.

Type IV resistant starch increases cecum short chain fatty acids level in rats.

Resistant starches are type of dietary fibers. However, their physiological effects depend on the way they resist digestion in the gastrointestinal tract. The objective of this study was to examine the hypothesis that new type of RS4 preparations, of in vitro digestibility of about 50%, obtained by cross-linking and acetylation, acts as a prebiotic by increasing short chain fatty acids content in cecum digesta. The rats were fed with diet containing pregelatinized, cross-linked and acetylated starches as a main carbohydrate source. Pregelatinized, but not chemically modified, potato starch was used in the composition of the control diet. After two weeks of experiment the increase of short chain fatty acids contents in ceceum digesta was observed. The intake of starch A, cross-linked only with adipic acid, resulted in increase of about 40% of short chain fatty acids content, whereas starch PA cross-linked with sodium trimetaphosphate and adipic acid of about 50%. The utmost twofold increase was observed in the case of the production of propionic acid. In contrast, the content of butyric acid increased (12%) only as an effect of consumption of starch PA and even decreased (about 30%) in case of starch A. Both RS4 starches caused an increase of the production of acetic acid by more than 40%. No changes in serum biochemistry, liver cholesterol and organ weights of rats were stated.

Sodium salt of starch octenylsuccinate as an emulsifier in "light" type mayonnaises.

INTRODUCTION: The E 1450 sodium salt of starch octenylsuccinate which exhibits emulsifying properties is used as food additive and is also recommended as yolk replacer in the process of mayonnaise production. Commercial E 1450 preparations reveal excellent functional properties in mayonnaise production. However, sodium salt of starch octenylsuccinate produced in the course of the suspension process (as well as the product of its hydrolysis in a membrane reactor), despite high surface activity, is unsuitable for this purpose. Therefore, a hypothesis was put forward that the cause of the unsuitability of these preparations for mayonnaise production is their improper profile of molecular mass distribution and the objective of this study was to verify the above thesis. MATERIAL AND METHODS: E 1450 preparations of different degree of substitution obtained alternately by means of reactive extrusion or enzymatic hydrolysis preceded by esterification in suspension were investigated. Preparations were characterised physico-chemically by determining the degree of substitution, viscosity, emulsifying activity index (EAI) and their capability to stabilise model emulsions (ME). Their molecular mass distribution profiles were determined and their suitability for the manufacture of low-fat mayonnaises was assessed. These investigations were also carried out for mixtures of preparations obtained as a result of a reactive extrusion and hydrolysis of the ester obtained during the suspension process. RESULTS: Despite the fact that the preparations obtained in suspension were characterised by 100% values of the ES parameter, all attempts to manufacture with their assistance of mayonnaise by way of a simple substitution in the formulation of dried egg yolk by E 1450 starch failed. Similarly, attempts to manufacture mayonnaise using any of the preparations obtained by means of reactive extrusion or enzymatic hydrolysis of the reaction product in suspension also ended in failure. The only successful solution was the application of equilibrium mixtures of E 1450 preparations obtained by way of reactive extrusion with a hydrolisate. Table 2 collates texture parameters of the obtained mayonnaises. CONCLUSION: The performed investigations fully corroborated the correctness of the proposed hypothesis that the suitability of the starch octenylsuccinate sodium salt as an emulsifier for low-fat mayonnaises is associated with the appropriately high polydispersity of this polymer.

Antioxidant activity of potato juice.

BACKGROUND: The interest in potato juice as a therapeutic agent goes back to the 19th century but its application was not supported by any knowledge about biological activity of this raw material. Factors restricting the medical application of potato juice include its inattractive sensory and functional properties. The aim of the presented investigations was preliminary evaluation of the biological activity of potato juice and the impact on it of some technological operations such as: cryoconcentration and hydrolysis in a membrane reactor. MATERIAL AND METHODS: Experiments comprised investigations of antioxidative potentials of fresh potato juice, products of its processing as well as fractions separated because of the size of their molecules using, for this purpose, Folin-Ciocalteu methods and reactions with the ABTS cation radical. RESULTS: The value of the antioxidative potential of fresh potato juice determined by means of the ABTS reagent corresponded to approximately 330 µmol/100 g which is in keeping with literature data. As a result of the cryoconcentration process, the value determined by the Folin-Ciocalteu method was found to increase only slightly whereas the value determined by means of the ABTS reagent almost tripled. The antioxidative potential was found to grow even more strongly in the case of the application of both methods when the process of enzymatic hydrolysis was employed. The total of 5 protein fractions of molecular masses ranging from 11 000 Da to over 600 000 Da, as well as an organic non-protein fraction of the molecular mass of 600 Da, were obtained as a result of the performed separation. All the examined fractions exhibited antioxidative activities. The highest values determined by the Folin-Ciocalteu method were recorded for the protein fraction of 80 000 Da mean molecular mass, while using the ABTS reagent--for the organic, non-protein fraction. CONCLUSIONS: Potato juice possesses antioxidative activity which can be enhanced by means of processing, especially, in the course of enzymatic hydrolysis. In addition, it was demonstrated that the organic nonprotein fraction of 600 Da mean molecular mass was characterised by the highest antioxidative activity.

Enzymatic hydrolysis of potato pulp.

BACKGROUND: Potato pulp constitutes a complicated system of four types of polysaccharides: cellulose, hemicellulose, pectin and starch. Its composition makes it a potential and attractive raw material for the production of the second generation bioethanol. The aim of this research project was to assess the usefulness of commercial enzymatic preparations for the hydrolysis of potato pulp and to evaluate the effectiveness of hydrolysates obtained in this way as raw materials for ethanol fermentation. MATERIAL AND METHODS: Sterilised potato pulp was subjected to hydrolysis with commercial enzymatic preparations. The effectiveness of the preparations declared as active towards only one fraction of potato pulp (separate amylase, pectinase and cellulase activity) and mixtures of these preparations was analysed. The monomers content in hydrolysates was determined using HPLC method. RESULTS: The application of amylolytic enzymes for potato pulp hydrolysis resulted in the release of only 18% of raw material with glucose as the dominant (77%) constituent of the formed product. In addition, 16% galactose was also determined in it. The hydrolysis of the cellulose fraction yielded up to 35% raw material and the main constituents of the obtained hydrolysate were glucose (46%) and arabinose (40%). Simultaneous application of amylolytic, cellulolytic and pectinolytic enzymes turned out to be the most effective way of carrying out the process as its efficiency in this case reached 90%. The obtained hydrolysate contained 63% glucose, 25% arabinose and 12% other simple substances. CONCLUSION: The application of commercial enzymatic preparations made it possible to perform potato pulp hydrolysis with 90% effectiveness. This was achieved by the application of a complex of amylolytic, cellulolytic and pectinolytic enzymes and the hydrolysate obtained in this way contained, primarily, glucose making it a viable substrate for ethanol fermentation.

Physicochemical properties of cross-linked and acetylated starches and products of their hydrolysis in continuous recycle membrane reactor.

The aim of the present work was to study the physicochemical properties of doubly modified, by cross-linking and acetylating, starches as well as the products of their enzymatic hydrolysis. A two step procedure of hydrolysis, including the batch and membrane reactors, were investigated. The second step of enzymatic processes were carried out in a continuous recycle membrane reactor (CRMR). Three kinds of commercial starches--two preparations of acetylated distarch adipate E1422 of different degrees of cross-linking, as well as one preparation of acetylated distarch phosphate E1414 were examined. It was found that the degree of substitution of acetyl groups in the macromolecules of starch did not influence the effectiveness of hydrolysis. However, the degree of cross-linking with adipate groups slightly decreased the efficiency of processing in the CRMR. Additionally, the relationship between the type of hydrocolloid and its adsorption activity in the air/water and oil/water systems was considered. All obtained derivatives revealed adsorption properties and reduced the surface/interface tension in the air/water and oil/water systems. The efficiency and effectiveness of adsorption of the investigated hydrocolloids were affected by the type of modification as well as the degree of substitution of acetyl groups in the macromolecules of starch. Particle size distributions formed in aqueous solutions for all investigated hydrolyses were determined and compared with results obtained for commercial products.

Buckwheat starch: structure, functionality and enzyme in vitro susceptibility upon the roasting process.

Starch of dehulled buckwheat grains with a moisture content of 14.5% before and after thermal treatment (160 degrees C/30 min) was used in this study. The crystal structure of buckwheat starch was of the A-type. The thermal process applied elicited slight changes both in infrared spectra and relative crystallinity on X-ray diffraction patterns. The scanning electron microscopy studies demonstrated polygonal and irregular shape of starch granules. After the thermal treatment, some breakings or conglomerates were noticed on the granules. The roasting process also affected a decrease in the swelling power and solubility. The release of glucose and changes in resistant starch after partial hydrolysis by pancreatic alpha-amylase and other intestinal enzymes were analysed as well. The scanning electron microscopy visualization indicated significant susceptibility of buckwheat starch at the beginning (0.5 h) and during 6 h in vitro amylolysis.

Surface activity of commercial food grade modified starches.

An attempt to quantitative evaluation of the functionality of food grade chemically modified starches in the emulsion systems by estimation of their surface activity as well as the capability of thickening food products was the main purpose of this present work. It was stated that chemically modified starches reveal higher surface activity at air/water and toluene/water interfaces in comparison to the native starch. The increase of the degree of substitution of polar carboxyl groups as well as rather non-polar acetyl ones results in an enhance of surface activity. Starch sodium octenylsuccinate stands out from other investigated starches, in its excellent capability of lowering surface and interfacial tension. Cross-linked starches reveal excellent stabilisation activity at a pH range of 5.5-7.0 but their surface activity is lower than those of other modified starches. Acetylated starch as well as starch sodium octenylsuccinate reveal satisfactory thickening capability up to pH 4.5 and moreover their surface activity (especially of E 1450) allows us to recommend them as functional constituents of food emulsions. Low thickening capability of oxidised starches rather excluded these derivatives from the group of potential functional additives for food emulsions.

Assessment of the classical MDR phenotype in epithelial ovarian carcinoma using primary cultures: a feasibility study.

This in vitro feasibility study has assessed a number of techniques and their applicability when looking at the role of multidrug resistance (MDR) in solid tumours. Fresh tumour material was obtained from 34 patients, (11 previously treated, 23 untreated) with ovarian adenocarcinoma. Doxorubicin sensitivity was measured using the MTT assay +/- the cyclosporins, Pgp expression was assessed by immunocytochemistry with the MRK-16 MoAb and flow cytometry was used to assess intracellular drug accumulation +/- PSC 833. 85% of samples showed some evidence of modest chemosensitisation by the cyclosporins (median 1.74-fold). We saw a marked variation in the number of Pgp positive cells between patients (1-87%, median 31%). 63% of samples tested showed an enhancement of DNR accumulation in the presence of PSC 833, with a median increase of 7% (sample range 0-29%). The present study highlights some of the technical difficulties encountered when working with fresh tumour material ex vivo. We conclude that screening of patients for their suitability to enter clinical trials incorporating MDR modulating agents is technically demanding, but feasible.