红外辐射联合回火与冷激杀菌技术对胡萝卜粉品质的影响

首先研究不同红外辐射温度(100,110,120℃)及辐射时间(2.5,5,10 min)对胡萝卜粉微生物及品质的影响,然后根据栅栏效应原理研究红外辐射-回火、红外辐射-冷激联合杀菌对胡萝卜粉微生物、色调值、类胡萝卜素含量等品质的影响。结果表明:100℃、10 min的红外辐射处理使细菌和真菌分别降低了1.9 lg(CFU/g)和2.32 lg(CFU/g),110℃、5 min的红外辐射处使细菌和真菌分别降低了1.58 lg(CFU/g)和2.57 lg(CFU/g)。在上述两种处理条件下胡萝卜粉的水分活度从0.238分别降至0.123和0.147,胡萝卜粉中总类胡萝卜素含量从308.8μg/g降至227.8μg/g和238.8μg/g,色差值(ΔE)为9.11和7.89。与红外辐射单独作用相比,联合回火后的处理没有显著影响细菌数目,处理后保持在5.40~5.80 CFU/g,霉菌、酵母数却在处理过程中显著减少,然而减少量较低,总数仍不低于4.5 lg(CFU/g)。红外辐射-冷激联合处理相比红外辐射单独处理,100℃、10 min联合冷激7 d处理可将细菌数量降低0.25 lg(CFU/g),可将霉菌与酵母数量降低0.28 lg(CFU/g),110℃、5 min联合冷激7 d处可将细菌数量降低0.26 lg(CFU/g),可将霉菌、酵母数量降低0.40 lg(CFU/g),且这些处理下胡萝卜粉的色调值、水分活度、类胡萝卜素含量变化不显著。本试验结果表明,红外辐射-冷激处理具有协同效应,且处理过程中胡萝卜粉的色调值及总类胡萝卜素含量不受影响,这为低水分粉体食品红外辐射联合杀菌提供了参考。

Effect of Infrared Radiation Combined Tempering and Freezing Sterilization Technologyon the Quality of Carrot Powders

The effects of different infrared radiation(IR)temperatures(100,110,120℃)and radiation time(2.5,5,10 min)on the microbial population and quality of carrot powder with high bacterial load were firstly investigated,the effects of infrared radiation-freezing and infrared radiation-tempering treatment on the microbial population,color and carotenoid quality of carrot powder were further investigated according to the principle of the fence effect.Infrared radiation treatment at 100℃and 10 min reduced bacteria,mold and yeast by 1.9 lg(CFU/g)and 2.32 lg(CFU/g),respectively.Infrared radiation at 110℃and 5 min reduced bacteria and fungi by 1.58 lg(CFU/g)and 2.57 lg(CFU/g),respectively.The water activity of carrot powder decreased from 0.238 to 0.123 and 0.147,respectively.The total carotenoid content in carrot powder decreased from 308.8μg/g to 227.8μg/g and 238.8μg/g,respectively.The total color difference(ΔE)was determined to be 9.11 and 7.89,respectively.Compared to IR treatment alone,combination of infrared radiation and tempering treatment on the effects of microorganism inactivation in carrot powder was weak,the total content of bacteria remained at 5.40-5.80 lg(CFU/g)after treatment.Mold and yeast counts were significantly reduced through treatment but was not lower than 4.5 lg(CFU/g).While,combination of infrared radiation(100℃and 10 min)and freezing treatment(7 d)finally reduced the bacterial population of 0.25 lg(CFU/g),while reduced the amount of mold and yeast of 0.28 lg(CFU/g).Under the condition of infrared radiation(110℃and 5 min)and freezing treatment(7 d),the contents of bacteria,mold and yeast were reduced 0.26 lg(CFU/g)and 0.40 lg(CFU/g).In these conditions,the color,water activity,and carotenoid content of carrot powder were not affected significantly.This experiment provides a reference for the study of infrared radiation combined sterilization of low moisture powder foods.