欧洲实验生物学杂志 开放获取

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Combination of high frequency electromagnetic induction with thermal processing for shelf life prolongation of packed vegetables meal

Nazanin Zand

The combination of high frequency electromagnetic induction, with different condition of thermal processing (80- 85 ^oc) has been studied for sterilization of vegetables meal and also the effect of this treatment evaluated on sensory properties of these meals. In this method all samples were filled in pouches (retort multilayer flexible films). EMI treatment which discharges square-wave pulses with variable voltage 1-20 kV/cm , with different frequency(2-3GHz ,3-4 GHz ,4-5GHz. 5-6 GHz ) have been done in step one . The usage of high frequency electromagnetic on clostridium and bacillus was not adequate because spore of these bacteria are practically resistant in electric fields, so pouches have been put in water bath chamber ,and different condition of pre heating (80^oc 5min; 80^oc 10min; 80^oc 15min, 85^oc 5min; 85^oc 10min; 85^oc 15min) have been done ,so the effect of each thermal processing combined with best result of electromagnetic field for these meals which belonged to 5-6 GHz. If cells are cultivated at higher temperature, this increasing tendency which can permanently keep fluidity viscosity of the cell membrane before electromagnetic field thus EMI efficiency was increased. The populations of mesophile microorganisms depended on type of treatment, type of meal ,and type of culture ,so the death ratio of mesophile microorganisms increasing in vegetables meal( without spice) 14466 percent more than vegetables meal (with spice). However, in every conditions of this process growth of thermophile microorganism has not been reported.During the period of this experiment (2 - 12 months) appearance, color , texture , odor, as oranoleptic properties of these samples in various conditions , had no significant differences and also the taste and mouth feel of vegetables meal ( without spice) during (2 - 12 months) had no significant differences too, but in last months (10 -12) these properties in vegetables meal ( with spice) was unpleasant, so we can estimate shelf life of meal 1 two month more than meal 2 in ambient temperature.