Effects Of Infrared Irradiation And Electron Beam On The Quality Of Carrot Powder

Carrot powder is an important dried carrot product,and there are potential problems of exceeding the standard of microorganisms.To solve this problem,the infrared radiation(IR)and electron beam(ebeam)sterilization technology were evaluated in this experiment.The specific research contents and results are as follows:(1)The effects of IR sterilization technology,IR?chilling and IR?temper combination sterilization technology on the qualities of carrot powder(microorganism,color and carotenoid content)were studied.The results showed that compared with IR treatment alone,combination of IR and tempering treatment on the effects of bacteria inactivation was nonsignificant,the total content of bacteria remained at 5.40-5.80 log CFU/g after treatment.Mold and yeast counts were significantly reduced through treatment but was not lower than 4.5 log CFU/g.Meanwhile,combination of IR and chilling treatment reduced the bacterial and molds and yeasts population by 0.25,0.26 log CFU/g and0.28,0.40 log CFU/g,respectively.In this process,the color,water activity,and carotenoid content of carrot powder were not affected significantly.The results showed that IR?chilling and IR?temper combination sterilization technology could improve the germicidal efficacy of IR,but the germicidal efficacy was weak.(2)Heat pump-dried and freeze-dried carrot powders packed in air or under vacuum were treated with 0,2.5,5,7.5,10 k Gy e-beam irradiation,microbial counts and microbial compositions,physical properties(moisture content,water activity,color values),chemical properties(total carotenoid content,total phenolic content,antioxidant ability)and sensory quality were then evaluated.E-beam can significantly decrease the microbial counts in various carrot powders,with the linear increase of irradiation dose,the extractable content of total carotenoids and total phenolic increased to 1.75 times(2.5 k Gy vacuum packaging dried carrot powder),1.37 times(10 k Gy air packaging dried carrot powder),respectively.The antioxidant activities of DPPH,FRAP and ABTS increased to 1.54 times(10k Gy air package dried carrot powder),1.58 times(10 k Gy air package dried carrot powder)and 1.81times(10 k Gy vacuum package freeze dried carrot powder),respectively.The sensory quality of carrot powder had no significant change.(3)The carrot powders irradiated by different irradiation doses(0,5,10 k Gy)during 84 d storage was studied.The variations of microbial quantity(total number of bacteria,yeast and mold),chemical quality(total phenol content,DPPH,FRAP,total carotenoid content),physical quality(water content,water activity,color)were evaluated.There was no significant change in the number of microorganisms in carrot powder treated by electron beam during 84 d storage.The antioxidant capacity and total phenol content of carrot powders first decreased and then increased.Temperature and packaging methods had no significant effect on antioxidant and total phenol content of carrot powder.The content of total carotenoids decreased significantly,and the highest retention rate was about 66% in freeze-dried carrot powder stored at 25 ?.