| Recently, Irradiation technology has been widely used in food industry, the international trade for irradiated food, especially agricultural food, has been gradually developed. The irradiated food has been involved in every part of our daily life, at the same time irradiation technology is also an important international strategy. Meanwhile, the related problems which are caused by the food safety and health have aroused the attention of government department.In this paper, the fatty compound contained agricultural foods (soybean, peanut, sameseed) are chose for the experiment, by the detecting of electron spin resonance (ESR). The ESR spectrum of these three kinds of food, under different irradiated doses from0.3to11.5kGy, the corresponding relationship between the doses and signal intensity, and difference between these three kinds of food under the same irradiated dose, are all researched. Different factors such as restore temperature restore time and thermodynamics features of the heated samples are researched to reveal the behavior of the radicals and the effecting factors. In the research of exploration of radicals which produced in the process of the irradiating, the thermodynamics features and decay kinetics of the radicals, and the debugging and optimizing of the parameters of the equipment which are all novel in the domestic current study of food irradiating. That is what provide theoretical basis to access to initial irradiating dose, the type of initiating radicals and the factors during the storing process. The main content and results in the paper are presented as following.The debugging and optimism are taken for the equipment. The main task contain selecting of working parameter of the equipment which are respectively microwave frequency, microwave power, the setup of magnetic field, amplitude modulation and scanning time, which are used to optimizing signal to noise ratio, resolution and stability of the equipment to optimize the test spectrum.These three kinds of Soybean, peanut and sesame were used as experimental materials which were irradiated to different doses from0.3to11.5kGy. Making these three kind of powder into zip lock bag to process irradiating in the room temperature. The results showed that the ESR signal intensity was positively related with their radiation dose. After irradiation the ESR intensity and spectrum shape all had changed and we could identify whether or not three kinds of food had been irradiated. The ESR intensities have positive relationship with the absorbing dose.Storing these three kinds of irradiated sample respectively into room temperature (293K), refrigerated storage (278K) and frozen preservation (258K) for five days, to detect the ESR signal. It can be concluded that, the colder the storing temperature is the more stable the ESR signal of the samples. The frozen preservation is most in favor of keeping the signal. The main reason can be presented as the higher the irradiated dose, the more concentration background of the irradiated-induce radicals, it can be better preserved in the lower temperature to reduce the radical’s activity. The common main composition of these three samples is unsaturated fatty acid which will produce a or β central carbon atom combining organic radicals.It can be observed that the ESR spectrum of the soybean is the overlap of single and triplet peak, and the g factor is2.005, which is produced by the unpaired electron in the carbon atom. The integrate ESR absorbing spectrum can be divided into the individual peak by changing the microwave power, because of different peak have relaxation time of electrons which will result different saturate properties.Thermodynamics research has been on the sex hormone of the soybean sample which caused by the manganese metal. Choosing the absorbing dose of10kGy (1day) soybean sample to heated respectively to313,323,343,363,373and383K, keep for certain time which are set by3,6,10,15,25,40,60,90min, then cooling to the room temperature to collect the ESR spectrum to get the signal of Mn2+and radicals. Blank sample are closed under the same process to eliminate the temperature effects for the sample self. We can see that the higher the temperature the more unstable of the radicals. The water gradually volatilizing and the skin part is broken which is the initial increasing of the ESR signal before323K. when the temperate gets higher, the carbon chain begin to separate in the unsaturated fatty acid to produce new organic radicals, and the number of the nitrogen and oxygen which combine with the protein have been changed, which results valence state of manganese being oxidized from plus2to plus3even more higher.Researched are on the experiments of storing. The storing time are set as1,5,10,15,20,25,30,40,60,90,120,150,180days to detect the relationship between time and radicals signals. During the storing time, the ESR signal have Different degrees of attenuation, it can still be distinguish the irradiated and irradiated samples. |
PDF Full Text Request