Modelling temperature and pH dependence of lipase and peroxidase activity in Turkish hazelnuts

Seyhan, Ferda; Tijskens, L.M.M.; Evranuz, Özgül

doi:10.1016/s0260-8774(01)00130-3

Cited by 34 publications

(28 citation statements)

References 42 publications

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“…Anatolia is ranked fourth in the world with 136 000 tonnes of walnut (Juglans regia L.) production (FAO, 2002). This production is mostly from seedling trees, but cultivation of new walnut cultivars from selective breeding programmes in Turkey leads to a standard walnut production (Koyuncu et al, 2004;Seyhan et al, 2002). In this respect, in Turkey the identification of walnut standard types has been developing and their production is being encouraged to increase the market share in the world.…”

Section: Introductionmentioning

confidence: 99%

Fatty acid composition of some walnut ( <i>Juglans regia</i> L. ) cultivars from east Anatolia

Doğan¹,

Akgül²

2005

Grasas y Aceites

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RESUMEN Composición en ácidos grasos de cultivos de nueces (Juglans regia L.) del Este de Anatolia.En este estudio se ha determinado la composición en ácidos grasos de diferentes cultivos de nueces (Juglans regia L.) producidos en Adilcevaz en el Este de Anatolia. El contenido de aceite total de las nueces osciló entre 65.00 ± 0.06 y 70.00 ± 0.58 %. El contenido en ácido oleico varió desde 22.63 a 27.27 % respecto a los ácidos grasos totales mientras que los contenidos en ácido linoleico y linolénico variaron desde 49.93 hasta 54.41 % y desde 14.32 hasta 17.82 % respectivamente. El contenido en ácido palmítico de las muestras de nueces estuvo comprendido entre 5.61 y 5.82 % mientras que de ácido miristico solo se encontraron trazas ( < 0.1 %). Finalmente, los resultados de los ácidos grasos indicaron que los cultivos de nueces del Este de Anatolia son distintos en cuanto a su perfil de ácido linolenico. Estos resultados pueden ser significativos para estudios de selección en orden a identificar mejor las variedades de nueces para dietas saludables. PALABRAS-CLAVE: Acido graso -Adilcevaz-Anatolia -Composición proximal -Nuez. SUMMARY Fatty acid composition of some walnut (Juglans regia L.) cultivars from east Anatolia.In this study, the fatty acid composition of different walnut (Juglans regia L.) cultivars grown in Adilcevaz in east Anatolia was determined. The total oil content of the walnuts ranged from 65.00 ± 0.06 to 70.00 ± 0.58 %. The oleic acid content of the oils ranged from 22.63 to 27.27 % of the total fatty acids while the linoleic acid and linolenic contents ranged from 49.93 to 54.41 % and 14.32 to 17.82 % respectively. The palmitic acid content of the walnuts ranged from 5.61 % to 5.82 % while there was a trace amount of miristic acid (<0.1 %) in the samples. Finally, the fatty acid results indicated that walnut cultivars from east Anatolia were distinctive in terms of their linolenic acid profile. These results might be significant for selection studies in order to better identify walnut varieties for healthy diets.

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Section: Introductionmentioning

confidence: 99%

Fatty acid composition of some walnut ( <i>Juglans regia</i> L. ) cultivars from east Anatolia

Doğan¹,

Akgül²

2005

Grasas y Aceites

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“…Information on materials and method with respect to produce and measuring methods can be found in Greiner and Konietzny (1999), Tijskens et al(2001a), Seyhan et al (2001), Gunawan and Barringer (2000) and Tijskens et al (2001b).…”

Section: Methodsmentioning

confidence: 99%

“…As already pointed out (Tijskens and Biekman 2001, Tijskens et al 2001aand Seyhan et al 2001, the effect of pH on enzyme activity can be deduced as:…”

Section: Effect Of Phmentioning

confidence: 99%

pH EFFECTS IN FOODS: DEVELOPMENT, VALIDATION AND CALIBRATION OF A FUNDAMENTAL MODEL

Tijskens¹,

Biekman²,

Greiner³

et al. 2001

Acta Hortic.

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SUMMARYThe effects of pH observed in the activity of a number of enzymes from different origins and the degradation of green colour in blanched vegetables, was modelled based on fundamental kinetic principles by considering hydrogen ions as an integral part of the reaction mechanism. Parameters were estimated by nonlinear regression analysis with explained parts (R 2 adj ) was in all cases except for the enzyme lipase, well over 95%, and frequently well over 98%. Applying fundamental models in integral data analysis made it possible to pinpoint aberrations at high and low pH ranges in the discoloration of vegetables, which r emained unnoticed using classical analysis procedures. The model on enzyme activity was successfully applied to analyse and to describe a double optimal pH region when iso-enzymes are present in the total pool of active enzymes. INTRODUCTIONEnzymes play a major role in our daily food, during growth, during processing, during storage, and during eating. The far most important external factor in all processes, including enzymatic ones, is temperature. In certain circumstances, however, pH can also be a significant external factor determining the process kinetics and the process rates. Although the theory on pH behaviour in buffered and unbuffered solutions is, for more then a century, well established and well understood (see previous lecture), the effects of pH are still modelled in a very empirical fashion. Most of the time polynomials of second order or higher are used to model the effect of pH (Zwietering 1993, Wijtzes 1996. This paper describes a model, which was developed based on simple but very plausible and fundamental considerations and assumptions, for the combined effects of temperature and pH on enzyme activity. The model was calibrated by multiple non-linear regression based on data of phytase activity from seven different origins and on data of lipase and peroxidase activity from hazelnuts. The same fundamental approach was used to described the effects of pH on the degradation of green colour (extraction of Mg

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“…The dependence of experimental data on pH was modeled according to Tijskens et al (2001) and Seyhan et al (2002) …”

Section: Calculationsmentioning

confidence: 99%

“…Our aim was to see if there is a difference in pH dependence between these two pools of isoenzymes and their contribution to the dependence of POD activity on pH in the extract containing all isoenzymes. Furthermore, we aimed to see if the sum of components, each described by the proposed mathematical model (Tijskens et al 2001;Seyhan et al 2002), can be used as a tool to describe a more complex POD activity/pH dependence, where two or more enzyme forms are present. The mathematical model applied to the obtained results can improve our predicting of changes in the enzyme activity over a wide range of pH values and shed more light on the behavior of this particular enzyme.…”

Section: Introductionmentioning

confidence: 99%

The effect of pH on the activity of soluble peroxidase in needles of Serbian spruce (Picea omorika (Panč.) Purkinye): application of a mathematical model

Laketa¹,

Bogdanović²,

Prodanović³

et al. 2010

gpb

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Abstract.We studied the dependence of peroxidase (POD) activity on pH in crude extract of Picea omorika (Panč.) Purkinye needles and in its acidic and basic fractions, obtained by ion exchange chromatography. Nonlinear regression was applied on the activity data with pH as the explaining variable, using the Levenberg-Marquardt algorithm. Studying crude extract at three different temperatures, the shape of the simulated activity/pH dependences indicated an existence of two components, which was confirmed by mathematical modeling. The kinetic parameters Act 0 , K EH and K EOH of both components are presented. The curves and pH optima shifted under increasing temperatures towards lower pH values, which was verified after decomposition. Nonlinear regression detected the presence of two components for both fractions, and there is no considerable difference between their pH optima. Our results show for the first time that the sum of components, each described by the mathematical model employed, can be used to explain the complex pH-related POD activity in the extract with two or more enzyme forms simultaneously active.

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Modelling temperature and pH dependence of lipase and peroxidase activity in Turkish hazelnuts

Cited by 34 publications

References 42 publications

Fatty acid composition of some walnut ( <i>Juglans regia</i> L. ) cultivars from east Anatolia

Fatty acid composition of some walnut ( <i>Juglans regia</i> L. ) cultivars from east Anatolia

pH EFFECTS IN FOODS: DEVELOPMENT, VALIDATION AND CALIBRATION OF A FUNDAMENTAL MODEL

The effect of pH on the activity of soluble peroxidase in needles of Serbian spruce (Picea omorika (Panč.) Purkinye): application of a mathematical model

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