Ems 104 epr analyzer

The papaya nectar samples were submitted to gamma radiation using the Gammacell 220 Excel irradiator, MDS, Nordion, by Cobalt 60 source, located at the Center for Nuclear Energy in Agriculture (CENA/USP). The doses 0 and 1 kGy were used under a dose rate of 0.712 kGy.h -1 . Dosimetry was performed using 5-mm-diameter alanine dosimeters (Bruker Instruments, Rheinstetten, Germany), and the free radical signal was measured with Bruker EMS 104 EPR Analyzer.
The actual dose was within 0.02 of the target dose. Samples were turned 360 o continuously during the irradiation process to achieve uniform target doses and the non-irradiated control was placed outside the irradiation chamber to have the same environmental temperature effect as that of their radiated sample.
The samples were analyzed at 2 different times: 0 and 120 days after irradiation with 60Co. Both analyses were carried out according to normative instruction no. 37/2018 and RDC 12/2001 [7, 12] .

Okra were purchased from ESALQ's Horticulture Department and taken to the Food Irradiation and Radio entomology Laboratory of the Nuclear Energy Center in Agriculture (CENA/USP), where they were selected about the size and absence of mechanical and phyto pathological damage. Then they were placed in styrofoam trays (21 x 21 cm), which were covered with plastic film (PVC).
After making the trays, they were irradiated one day after harvesting in a Cobalt-60 radiator, type Gammabeam 650, with doses of 0 (control); 75; 100; 125; 150 and 200 Gy, under a rate of dose of 0.259 kGy.hour -1 , and each treatment consisted of 4 repetitions and stored at 10ºC and 80% RH. Dosimetry was performed using 5 mm diameter alanine dosimeters (Bruker Instruments, Rheinstetten, Germany), and the free radical signal was measured with Bruker EMS 104 EPR Analyzer. The actual dose was within 0.02 of the target doses. Samples was turned 360 continuously during the irradiation process to achieve uniform target doses and the non irradiated control was placed outside the irradiation chamber to have the same environmental temperature effect with the irradiating sample.
After 7 and 15 days from the irradiation, it was evaluated the physico-chemical analyses.

The measurements of the ESR -spectra were made using Bruker EMS 104 EPR Analyzer fitted with a double rectangular cavity. In order to ensure the reproducibility and stability of measurements, the instrument calibration was carried out daily before each measurement. This was achieved for checking the response and setting of EPR spectrometer by means of solid 1, 1-diphenyl-2-picrylhydrazyl (DPPH), a strong pitched standard (Bruker). For ensuring the accurate and reproducible position of the sample in the cavity of instrument, a positioning template was used for each sample present in the ESR quartz tubes and desired height was adjusted through parameter settings of the instrument.
As the samples of the spices under consideration contained cellulose, the spectrometric settings were in accordance with protocol of CEN specified for the food containing cellulosic material (EN1787 2000). Therefore, the operating conditions used in this study were: microwave frequency of 9.8 GHz and microwave power of 0.8 mW; centre field of 348 mT (3480 Gauss) and sweep width of 20 mT (200 Gauss); modulation frequency of 50 kHz and modulation amplitude of 0.8 mT (8 Gauss) with time constant (filter t.c) of 40.96 ms and sweep time 42 s sweep -1 ; 10 sweeps spectrum -1 ; receiver gain between 45-50 dB; spectral record taken at room temperature.