Özlem Güçlü-Üstündağ

Bio: Özlem Güçlü-Üstündağ is an academic researcher from Yeditepe University. The author has contributed to research in topics: Supercritical carbon dioxide & Extraction (chemistry). The author has an hindex of 9, co-authored 12 publications receiving 1048 citations. Previous affiliations of Özlem Güçlü-Üstündağ include Agriculture and Agri-Food Canada & University of Alberta.

Saponins: Properties, Applications and Processing

Abstract: Saponins are a diverse group of compounds widely distributed in the plant kingdom, which are characterized by their structure containing a triterpene or steroid aglycone and one or more sugar chains. Consumer demand for natural products coupled with their physicochemical (surfactant) properties and mounting evidence on their biological activity (such as anticancer and anticholesterol activity) has led to the emergence of saponins as commercially significant compounds with expanding applications in food, cosmetics, and pharmaceutical sectors. The realization of their full commercial potential requires development of new processes/processing strategies to address the processing challenges posed by their complex nature. This review provides an update on the sources, properties, and applications of saponins with special focus on their extraction and purification. Also reviewed is the recent literature on the effect of processing on saponin structure/properties and the extraction and purification of sapogenins.

Solubility behavior of ternary systems of lipids, cosolvents and supercritical carbon dioxide and processing aspects

Abstract: Phase behavior of solutes in supercritical fluids can be modified by the addition of small amounts of cosolvents. The addition of a cosolvent may increase solubility selectively or non-selectively. This solubility enhancement results from an increase in solvent density and/or intermolecular interactions and can be used to improve the feasibility of a process by improving solvent loading and/or selectivity. The effects of cosolvent addition on the solubility behavior of solutes and on various aspects of SCCO2 processing were assessed with special emphasis on lipids. The cosolvent effect in ternary systems of lipid components (fatty acids (palmitic, stearic and behenic acids), β-carotene, squalene, stigmasterol), cosolvent (ethanol) and SCCO2 was quantified as the ratio of solubility obtained with cosolvent addition to that without a cosolvent. The effects of operating conditions, cosolvent concentration, and cosolvent and solute properties on the cosolvent effect were identified. Cosolvent effects for these solutes were compared and implications for fractionation were noted. Solubility enhancement was observed for all lipid systems, but to different extents. Cosolvent effect for fatty acids decreased with pressure. Specific intermolecular interactions (H-bonding) between the fatty acids and ethanol contribute significantly to the cosolvent effect and can be exploited to increase selectivity of a fractionation process. Study of the use of cosolvents for any process should entail a case by case analysis, which takes into account the effect of the cosolvent not only on the solubility behavior but also on mass transfer properties, process design, quality of the extract and/or the residue, post processing steps such as compositional analysis and cost.

Correlating the solubility behavior of minor lipid components in supercritical carbon dioxide

Abstract: Isolation of minor lipid components from complex lipid mixtures is receiving increased attention due to their biological activity and health benefits. Therefore, properties, health benefits and processing aspects of minor bioactive lipid components were reviewed. Literature solubility data of binary mixtures of minor lipid components (β-carotene, α-tocopherol, stigmasterol and squalene) and supercritical carbon dioxide (SCCO2) were correlated using Chrastil’s equation to determine the general trends of solubility behavior as affected by operating conditions and solute properties. Model parameters were estimated for the whole temperature range (a, b, k) and at each temperature (b′, k′). The slopes of solubility isotherms (k′) were in the range of 4.9–10.6 for β-carotene, 4.5–9.6 for α-tocopherol, 4.9–8.0 for stigmasterol and 7.3–7.6 for squalene. Estimated model parameters were used to compare solubility behavior of these solutes with components of olein glyceride series (oleic acid and triolein) as representatives of major lipid classes found in fats and oils. The findings provide the basis for the study of multicomponent lipid mixtures. Differences in the solubility behavior of components and the effect of operating conditions on solubility can be exploited for fractionation of these multicomponent mixtures to isolate the bioactive minor lipid components.

Solubility behavior of ternary systems of lipids in supercritical carbon dioxide

Abstract: In this review, the phase behavior of lipids in ternary and higher systems was analyzed to determine the effect of operating parameters and feed composition on solubility behavior and separation efficiency. The ternary systems studied included two triglycerides (TG) (trilaurin (LLL)/tripalmitin (PPP), trimyristin (MMM)/PPP and LLL/MMM), two fatty acids (FA) (oleic acid (OA)/linoleic acid (LA)), two fatty acid methyl esters (FAME) (methyl myristate (MeM)/methyl palmitate (MeP) and methyl oleate (MeO)/methyl linoleate (MeL)), FA/TG (OA/triolein (OOO)) and FAME/FA (MeO/OA) in SCCO2. The quaternary and quinary systems analyzed contained three TG (LLL/MMM/PPP), three glycerides (monoolein (MO)/diolein (DO)/OOO) and four TG (PPP/palmitoyl-dioleoylglycerol (POO)/oleoyl-dipalmitoylglycerol (PPO)/OOO), respectively, in SCCO2. While solubility of the less soluble component increased in ternary systems of solid triglycerides in SCCO2, that of the more soluble component decreased or was not affected. Solubility diminution was observed for both solutes in some liquid mixtures such as fatty acid (oleic acid/linoleic acid) and fatty acid ester (methyl oleate/methyl linoleate) mixtures. Solubility enhancement for one of the mixture components was also observed (for example, for oleic acid in the presence of methyl oleate). Separation efficiency was lower than that predicted by binary data when the solubility of the less soluble solute was enhanced in the mixture, whereas it was improved if the solubility of the more soluble component was enhanced as observed in quaternary glyceride mixtures.

New hypotheses for the health-protective mechanisms of whole-grain cereals: what is beyond fibre?

Abstract: Epidemiological studies have clearly shown that whole-grain cereals can protect against obesity, diabetes, CVD and cancers. The specific effects of food structure (increased satiety, reduced transit time and glycaemic response), fibre (improved faecal bulking and satiety, viscosity and SCFA production, and/or reduced glycaemic response) and Mg (better glycaemic homeostasis through increased insulin secretion), together with the antioxidant and anti-carcinogenic properties of numerous bioactive compounds, especially those in the bran and germ (minerals, trace elements, vitamins, carotenoids, polyphenols and alkylresorcinols), are today well-recognised mechanisms in this protection. Recent findings, the exhaustive listing of bioactive compounds found in whole-grain wheat, their content in whole-grain, bran and germ fractions and their estimated bioavailability, have led to new hypotheses. The involvement of polyphenols in cell signalling and gene regulation, and of sulfur compounds, lignin and phytic acid should be considered in antioxidant protection. Whole-grain wheat is also a rich source of methyl donors and lipotropes (methionine, betaine, choline, inositol and folates) that may be involved in cardiovascular and/or hepatic protection, lipid metabolism and DNA methylation. Potential protective effects of bound phenolic acids within the colon, of the B-complex vitamins on the nervous system and mental health, of oligosaccharides as prebiotics, of compounds associated with skeleton health, and of other compounds such as alpha-linolenic acid, policosanol, melatonin, phytosterols and para-aminobenzoic acid also deserve to be studied in more depth. Finally, benefits of nutrigenomics to study complex physiological effects of the 'whole-grain package', and the most promising ways for improving the nutritional quality of cereal products are discussed.

Nutrition facts and functional potential of quinoa (Chenopodium quinoa willd.), an ancient Andean grain: a review.

Abstract: Quinoa, Chenopodium quinoa Willd., is an Amaranthacean, stress-tolerant plant cultivated along the Andes for the last 7000 years, challenging highly different environmental conditions ranging from Bolivia, up to 4.500 m of altitude, to sea level, in Chile. Its grains have higher nutritive value than traditional cereals and it is a promising worldwide cultivar for human consumption and nutrition. The quinoa has been called a pseudo-cereal for botanical reasons but also because of its unusual composition and exceptional balance between oil, protein and fat. The quinoa is an excellent example of ‘functional food’ that aims at lowering the risk of various diseases. Functional properties are given also by minerals, vitamins, fatty acids and antioxidants that can make a strong contribution to human nutrition, particularly to protect cell membranes, with proven good results in brain neuronal functions. Its minerals work as cofactors in antioxidant enzymes, adding higher value to its rich proteins. Quinoa also contains phytohormones, which offer an advantage over other plant foods for human nutrition. c � 2010 Society of Chemical Industry

Saponins as cytotoxic agents: a review

Abstract: Saponins are natural glycosides which possess a wide range of pharmacological properties including cytotoxic activity. In this review, the recent studies (2005–2009) concerning the cytotoxic activity of saponins have been summarized. The correlations between the structure and the cytotoxicity of both steroid and triterpenoid saponins have been described as well as the most common mechanisms of action.