Wyniki wyszukiwania - Biblioteka Nauki

1

Reliability of light-stimulated photoluminescence (PSL) in detection of irradiated food comparison with thermoluminescence method (TL)

100%

Guzik G. P. , Stachowicz W.

|

2008

|

tom Vol. 53, suppl. 1

25-29

EN

The detection of irradiation of several classes of food products with the use of thermoluminescence (TL) and photostimulated luminescence (PPSL) has been proceeded. The comparison of the results obtained by both methods has been done and reliability of the PPSL method as compared with the TL method evaluated. Conclusion concerning the usefulness of such evaluation to the practice has been drawn.

2

Study on organic radicals giving rise to multicomponent EMR spectra in dried fruits expose to ionizing radiation II. D-Glucose

100%

Guzik G. P. , Stachowicz W.

|

tom Vol. 58, No. 3

425--428

EN

Crystalline D-glucose extracted from dried resins was irradiated with 60Co gamma rays. The multicomponent EMR spectra of the samples kept at ambient temperature were compared with those heated at 105°C – the temperature close to the melting point of glucose. Normalized EMR spectra recorded with both samples were subtracted, resulting in a differential EMR spectrum. Spectral analysis of all three spectra has been done resulting in the identification of isotropic doublet of doublets assigned to less stable radical derived from parent glucose molecule.

3

Study on stable radicals produced by ionizing radiation in dried fruits and related sugars by electron paramagnetic resonance spectrometry and photostimulated luminescence method – I. D-fructose

80%

Guzik G. P. , Stachowicz W. , Michalik J.

|

2008

|

tom Vol. 53, suppl. 2

89--94

EN

Stability of sugar born radicals separated from irradiated Iranian dried raisins and from D-fructose by Sigma Aldrich has been studied at room temperature by EPR and PPSL methods in a period of 360 days. It has been proven for the first time experimentally that the complex EPR spectrum of irradiated sugars is changed in time and after heating. Hence, this made it possible to distinguish spectral lines of two specific radicals contributing to the formation of multicomponent spectra, recorded in both time dependent and heating experiments. The radicals measured by EPR and energy traps detected by PPSL decay at room temperature in a similar way, suggesting a similar distribution of both species in sugar crystallites. We think that our experimental approach might be useful to study interrelation between the formation and trapping of radicals and energy accumulated in crystalline matrices. In order to achieve the isolation of individual sugars from fruits the extraction and specific separation procedures have been adapted with the use of methanol, ethanol and water solvents. Our results clearly show that radicals induced by radiation in fruits (with fructose born radicals as major constituent) are stable enough at room temperature for easy identification of irradiated raisins using the EPR method.

4

EPR study on sugar radicals utilized for detection of radiation treatment of food

80%

Guzik G. P. , Stachowicz W. , Michalik J.

|

tom Vol. 57, No. 4

545-549

EN

Radicals produced by ionizing radiation in sugars, the components of dried and raw fruits give rise to stable multicomponent electron paramagnetic resonance (EPR) signals unidentified so far. The subject of the present EPR study is to identify the radicals stabilized in gamma-irradiated crystalline sugars, D(+)mannose and L(-)sorbose extracted from cranberries (Vaccininum oxycoccos) and rowan berries (Sorbus aucuparia), respectively. EPR measurements and density functional theory (DFT) simulations were employed for that purpose.

5

Identification of irradiated dried fruits using EPR spectroscopy

80%

Guzik G. P. , Stachowicz W. , Michalik J.

Nukleonika

|

2015

|

tom Vol. 60, No. 3, part 2

627--631

EN

The dominating carbohydrates in fruits are monosaccharides like fructose, glucose, sorbose and mannose. In dehydrated fruits, concentration of monosaccharides is higher than in fresh fruits resulting in the formation of sugar crystallites. In most of dried fruits, crystalline fructose, and glucose dominate and appear in proportion near to 1:1. Irradiation of dried fruits stimulates radiation chemical processes resulting in the formation of new chemical products and free radicals giving rise to multicomponent EPR signal which can be detected for a long period of time. For that reason, it is used as a marker for the detection of radiation treatment of dried fruits. It has been found that EPR spectra recorded in dried banana, pineapple, papaya, and fig samples resemble the EPR spectrum obtained by computer addition of fructose and glucose spectra taken in proportion 1:1. The decay of radiation induced EPR signals proceeds in dried fruits fast during the first month of observation and becomes much slower and almost negligible after prolonged storage. However, it remains intense enough for EPR detection even one year after processing. The radiation induced EPR signal is easily detected in dried fruits exposed to 0.5 kGy of gamma rays. Thus, the EPR method of the detection of irradiated fruits can be used for the control of dried fruits undergoing quarantine treatment with 200–300 Gy of ionizing radiation.