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Water activity in biological system - a review

100%

Schiraldi A., Fessas D., Signorelli M.

Polish Journal of Food and Nutrition Sciences

2012

tom 62

nr 1

Water deserves a major attention by researchers dealing with biological systems and related materials, like food, since it is ubiquitous and can be used like a “native” probe to garner information about the hosting system, provided it may be freely displaced across. Its thermodynamic potential, namely, the water activity, aW, is related to that of the other compounds of the system considered via the Gibbs-Duhem relationship refl ecting the extent of the residual availability of water to solvate further solutes and sustain the molecular mobility of the bio-polymeric compounds. As for the experimental approaches to aW, this short review re-addresses the reader to other publications, while devotes a section to the Knudsen thermo-gravimetry that was used by the authors to determine the desorption isotherms of many food systems and related aqueous compounds. The paper remarks the importance of a preliminary assessment of water mobility and recalls the concept of “critical aW“ that takes into account the reduced mobility of water molecules in the vicinity of the glass transition. This opens the question of the reliability of sorption isotherms which encompass a wide aW range and the interpretation of the observed adsorption/desorption hysteresis. The multi-phase character of many biological systems is another issue of interest related to the reliability of the experimental approaches to aW. As examples of the role of aW on the stability of bio-systems and on the practice of a technological treatment, protein unfolding and osmo-dehydration of fruit pulps are reported.

Electrophoretic and DSC studies on different wheat starches with various amylose contents

76%

Wasserman L. A., Vaccino P., Boggini G., Schiraldi A., Noda T., Kudryavzev A. M., Yuryev V. P.

Polish Journal of Food and Nutrition Sciences

2006

tom 15/56

nr 1

Granule-bound starch synthase and the structural and thermodynamic properties of the isolated starches were compared using amylopectin (2.1% amylose content), normal (20.5-25.1% amylose content) and high amylose (≥39.5% amylose) wheat cultivars of Japanese, Italian and Russian selections. Amylopectin (2.1% amylose content), normal (20.5-25.1% amylose content) and high amylose (amylose rich containing ≥39.5% amylose) wheat cultivars were investigated using an electrophoretic technique to examine starch-granule bound synthase. High-sensitivity differential scanning microcalorimetry was used to examine the structural and thermodynamic properties of extracted wheat starches. Wx-B1 protein was not present in normal and even in high amylose cultivars except for the normal amylose cultivar Bilancia. An increase in amylose content in starches is generally accompanied by a decrease both in the melting enthalpy and the melting temperatures of crystalline lamella, whilst the polymorphous structure of starches remains invariable (A-type). The melting cooperative unit, the thickness and the surface free energy, enthalpy and entropy of crystalline lamella were also determined. Classification of wheat starches with different amylose contents is offered.

Microstructure, thermal properties and susceptibility of the high amylose wheat starch to enzymatic hydrolysis: a new material for resistant starch (RIII) production

64%

Wasserman L. A., Kiseleva V. I., Schiraldi A., Blaszczak W., Fornal J., Sotnikova E. V., Gapparov M. M. G., Yuryev V. P.

Polish Journal of Food and Nutrition Sciences

2004

tom 13/54

nr 2

Differential scanning calorimetry, optical (LM) and scanning electron (SEM) microscopy methods were used for studying the properties and structure of type III resistant starches obtained from high amylose (39.5% amylose) wheat starch. The susceptibility of RSIII starch to enzymatic hydrolysis was also studied. This study has shown that the structure of the investigated, laboratory-obtained preparation was highly influenced by the processing parameters - indicating changes typical of a repeated heating-cooling process. Thermal properties connected with the presence of amylose-lipid complexes, as well as ordered structure fragments in the preparations, were in high accordance to those reported in literature for RSIII preparations from normal wheat, high amylose barley and pea starches as well as commercial types - Novelose 330 or CrystaLean. It was shown that high amylose wheat is a promising raw material for processing bakery and extrusion food products with a reasonably high content of resistant starches without the addition of commercial resistant starches to meal or extrusion mixture.

Ograniczanie wyników

3 Polish Journal of Food and Nutrition Sciences

3 Schiraldi A.

2 Wasserman L. A.

2 Yuryev V. P.

1 Blaszczak W.

1 Boggini G.

1 Fessas D.

1 Fornal J.

1 Gapparov M. M. G.

1 Kiseleva V. I.

1 Kudryavzev A. M.

1 Noda T.

1 Signorelli M.

1 Sotnikova E. V.

1 Vaccino P.

1 2012

1 2006

1 2004

Wyniki wyszukiwania

Water activity in biological system - a review

Electrophoretic and DSC studies on different wheat starches with various amylose contents

Microstructure, thermal properties and susceptibility of the high amylose wheat starch to enzymatic hydrolysis: a new material for resistant starch (RIII) production