GB 31642-2016National Food Safety Standard -- Determination of Irradiated Foods -- Electron Spin Resonance Spectroscopy (English PDF)

4.1 Sample Preparation

4.1.1 Animal food containing bone

Fascia completely removed meat and bone sample surface, to knock the bone into pieces, bone marrow is removed, if necessary, water or methanol - ether solution (41, volume ratio) washing, cleaning and clean so that the bones. After washing, the bone was placed in a vacuum oven dried (vacuum degree. 180Pa, frozen Temperature. -45 °C, drying time. 12h). The dried sample was pulverized to an average particle diameter of the bone about 1mm particles weighing 100mg, placed ESR sample tube to be tested.

4.1.2 Cellulose-containing foods

4.1.2.1 Dry Foods

Extraction with a suitable tool from the rind 50mg ~ 100mg sample was charged ESR sample tube to be tested.

4.1.2.2 Spice food

A sample 150mg ~ 200mg, ESR sample tube was placed and dried, the test.

4.1.2.3 Berry fruits

Take appropriate berry a 50mL plastic tubes, vortex mix. The sample was mixed into the large beaker, 500mL go Deionized water, stirring and blending glass rod. After the natural grain precipitation to remove excess water and pulp. Repeat the above steps to sufficiently remove residual fruit Pulp. The grain is spread on a filter paper to absorb excess water off, and then placed into a freeze dryer or a vacuum oven (40 °C) and dried 4h. Weigh 150mg ~ 200mg Full Grain mounted on ESR sample tube to be tested.

Note. The berries should be preserved grain, grinding and other operations will weaken the electromagnetic signal and may change the shape of the ESR spectrum.

4.2 Spectrometer reference condition

4.2.1 Animal food containing bone

Microwave frequency. 9.5GHz, power 5mW ~ 12.5mW.

Field. Center field 348mT, sweep width 5mT ~ 20mT.

Signal channels. modulation frequency 50kHz ~ 100kHz, modulation amplitude 0.2mT ~ 0.4mT, the time constant of 50ms ~ 200ms, sweep 71.448 --- conversion coefficient;

v --- microwave frequency in gigahertz (GHz);

--- magnetic induction B, in units of milli-tesla (mT).

Results retention to three decimal places.

Calculated g values need to measure the frequency and field location A.2 strong arrows in FIG.

5.1.2 Cellulose-containing foods

Center signal C (see Figure A.3) appear only ESR spectrum of the non-irradiated sample; in the ESR spectrum of the irradiated samples, the center signal C intensity is increased, and occurs in both the left and right split peak signal C1 and C C2, the distance between the two peaks 6.05mT ± 0.05mT (See Figure A.4).

5.2 Results found

5.2.1 Animal food containing bone

When g1 = 2.002 ± 0.001, when g2 = 1.998 ± 0.001, samples were subjected to irradiation treatment can be determined (as shown in FIG A.2, g1, and g2 min Do not appear on the asymmetrical signal indicative of ESR spectrum).

When g = 2.005 ± 0.001, can not determine whether the sample after the irradiation treatment.

5.2.2 Cellulose-containing foods

When the left and right both sides of the center signal C 6.05mT ± 0.05mT split peak distance can be determined through a sample irradiation treatment;

When the left and right sides of the center signal C peak no split, it is impossible to determine whether the samples after irradiation.

Appendix A

The non-irradiated and irradiated samples ESR spectra of FIG.

A.1 unirradiated ESR spectra of FIG chops ESR spectra of non-irradiated pork shown in Figure A.1.

FIG A.1 ESR spectrum of FIG unirradiated pork chops

A.2 ESR spectra of irradiated pork 1.0kGy FIG.

ESR spectra of irradiated pork chops 1.0kGy shown in Figure A.2.

Figure A.2 ESR spectra of irradiated pork 1.0kGy FIG.

A.3 non-irradiated happy husk of ESR spectrogram Happy husk unirradiated ESR spectra is shown in Figure A.3.

Figure A.3 non-irradiated happy husk of ESR spectrogram

A.4 irradiation 4.0kGy happy Nutshell ESR spectroscopy map Irradiation happy Nutshell ESR spectroscopy map 4.0kGy in Figure A.4.

Description.

C1 --- left peak;

C --- center signal;

C2 --- the right peak.

Figure A.4 irradiation 4.0kGy happy Nutshell ESR spectroscopy map