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Food Science

Food Structure

Irradiation

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Full-Text Articles in Life Sciences

Properties Of Irradiated Starches, A. S. Sokhey, M. A. Hanna Jan 1993

Properties Of Irradiated Starches, A. S. Sokhey, M. A. Hanna

Food Structure

Properties of irradiated starches have been outlined in this review . ')' -radiation generates free radicals on starch molecules which cause changes in starch properties . The intensity of free radicals is dependent upon starch moisture content , and temperature and duration of storage. Increasing dosages of -y-irradiation creates in creasing intensities of free radicals on carbohydrates. These free radicals are responsible for bringing about molecular changes and fragmentation of starch molec ules. Increasing ')' -irradiation dosages cause an in crease in acidity , and decreases in viscosity and water solubility of starches. The granule structure remains visually undamaged at low dosages of irradiation, but may ...


Luminescence Techniques To Identify The Treatment Of Foods By Ionizing Radiation, G. A. Schreiber, B. Ziegelmann, G. Quitzsch, N. Helle, K. W. Bogl Jan 1993

Luminescence Techniques To Identify The Treatment Of Foods By Ionizing Radiation, G. A. Schreiber, B. Ziegelmann, G. Quitzsch, N. Helle, K. W. Bogl

Food Structure

About a decade ago two luminescence techniques, thermoluminescence (TL) and chemiluminescence (CL), were first described as methods for the detection of irradiated spices. It has now been established that the CL method can be used to screen only certain foodstuffs for irradiation. The TL method, instead, has been developed for clear identification of foods irradiated with at least 1 kGy and contaminated by minerals. The method is therefore suitable for a wide range of foodstuffs and it has been applied by laboratories for routine control. The latest findings prove that even irradiation with very low doses used to inhibit the ...


Physicochemical Properties Of Irradiation Modified Starch Extrudates, A. S. Sokhey, R. Chinnaswamy Jan 1992

Physicochemical Properties Of Irradiation Modified Starch Extrudates, A. S. Sokhey, R. Chinnaswamy

Food Structure

Corn starch samples containing 0, 25, 50 and 70% amylose irradiated with -y -radiation dosages of 0 (native) , 5 , 10, 20 (containing 0, 2.5 or 5% potassium persulfate , hydrogen peroxide or eerie ammonium nitrate) or 30 kGy were extrusion cooked using a C. W. Brabender single-screw extruder at a barrel temperature of 140 °C, a screw speed of 140 rpm and 18% moisture content. Increasing irradiation dosages from 0 to 30 kGy gave consistently increased expansion ratios from 2.9 to 7.9 for 25% amylose starches and from 6.5 to 14.5 for 50% amylose starches, while ...


Effect Of Irradiation And Dielectric Heating On Soybean Ultrastructure, Trypsin Inhibitor, And Lipoxygenase Activities, E. Kovacs, N. D. Lam, J. Beczner, I. Kiss Jan 1991

Effect Of Irradiation And Dielectric Heating On Soybean Ultrastructure, Trypsin Inhibitor, And Lipoxygenase Activities, E. Kovacs, N. D. Lam, J. Beczner, I. Kiss

Food Structure

Scanning electron microscopy ( SEM) was used to observe the protein bodies of soybeans after irradiation (0 - 10 kGy dose range) , dielectric heating and storage . Microbiological changes , lip oxygenase and trypsin inhibit or activities and biological value were also studied after different treatments and storaee . There were no differences in the ultrastructure of control and irradiated ( 3, 6 and 10 kGy) soybeans immediately after irradiation . The effect of storage depended on whether whole or milled soybeans had been stored . There was no direct effect of dielectric he ating on soybeans ultrastruc ture , however , during storage it changed the same way as ...


The Effect Of Irradiation On Starch Content In Golden Delicious Apples, E. Kovacs, A. Keresztes Jan 1989

The Effect Of Irradiation On Starch Content In Golden Delicious Apples, E. Kovacs, A. Keresztes

Food Structure

Starch content in apple (Golden Delicious) skin and flesh was studied as a function of radiation dose (0, 0.5, 1, 2 and a 5kGy) after 8 weeks shelf life (16 C, 80-90% RH).

Starch was generally not found in the flesh with the exception of the 5 kGy sample. Starch grains were observed, however, in plastids of the epidermis and especially in the hypodermis in correlation with the radiation dose. 1 kGy dose caused a significant effect (p>99, 98%) on retardation of starch breakdown measured by electron microscopic morphometry and chemical analysis.

Analysis showed that increasing radiation dose ...


The Effects Of Gamma Irradiation And Calcium Treatment On The Ultrastructure Of Apples And Pears, E. Kovacs, A. Keresztes, J. Kovacs Jan 1988

The Effects Of Gamma Irradiation And Calcium Treatment On The Ultrastructure Of Apples And Pears, E. Kovacs, A. Keresztes, J. Kovacs

Food Structure

The post-storage quality of fruits depends on the ultrastructure of the outer tissues and on the fruit mineral composition (mostly on calcium). Pectins and their bonds with calcium play a central role in the tissues during ripening.

During senescence the middle lamella disappears from the cell walls, the fruits become soft and cell wall reticulation can be seen. There are changes within the cells too; plasmalemma separates from the wall, tonoplast from the cytoplasm, and plastids, mitochondria and nuclei are disorganized.

The ultrastructure of the skin and flesh of apples and pears were studied as a function of treatments (calcium ...


Effect Of Ionizing Irradiation And Storage On Mushroom Ultrastructure Ii. The Stipe And The Upper Part Of The Cap Of Agaricus Bisporus (Lge. Imbach), A. Keresztes, E. Kovacs Jan 1987

Effect Of Ionizing Irradiation And Storage On Mushroom Ultrastructure Ii. The Stipe And The Upper Part Of The Cap Of Agaricus Bisporus (Lge. Imbach), A. Keresztes, E. Kovacs

Food Structure

After having investigated t he ultra structural effects of ionizing irradiation used for shelf -life extension , on the gills of Agaricus bisporus and Pleurotus ostreatus previously , it was of interest to examine how other parts of the fruit body were affected by t he same treatment . Samples were taken from the lower and upper parts of the stipe and from the upper part of t he cap of the control , stored , and irradiate d (2.5 kGy ) t he n stored A. bisporus fruit bodies. Transmission electron microscopy sh owed that irradiated samples generally retained plasm- content , which dramatically decreased ...