Preparation Of Probiotic-rich Carrot Crumb And Its Storage Stability

This study aimed at obtaining probiotics enriched carrot slices.Firstly,the dipping method was used to enrich probiotics into carrot tissues and the process parameters of vacuum impregnation and ultrasonic impregnation were optimized.Secondly,the effects of hot air drying(AD),freezing drying(FD),hot air and explosion puffing combination drying(AD+PD),freezing drying coupling vacuum microwave(FD+MVD)on number of probiotics,production efficiency and quality indicators such as hardness,brittleness,vitamin C,?-carotene of carrot slices were evaluated to select the optimal drying method.Finally,the effects of different temperature and packaging methods on the quality of probiotics enriched carrot slices were studied.The main results are as follows:1.By orthogonal test,the optimum technological parameters of vacuum impregnation were obtained,which were temperature 35 ?,vacuum time 15min and restoration time 20min,and the optimum technological parameters of ultrasonic impregnation were temperature 30 ?,ultrasonic power 125W,impregnation time 12min.The enrichment effects of vacuum impregnation,ultrasonic impregnation and atmospheric pressure impregnation were compared and showed that the number of viable bacteria enriched by vacuum impregnation was the highest,reaching 1010CFU/g and the bacterial was colonized in the carrot tissues.Therefore,the vacuum impregnation was chosen as the enrichment method for the preparation of probiotics enriched carrot.2.Because of high temperature and long time,AD,AD+PD products lead to the serious loss of nutrition and probiotics,serious shrinkage,hard texture and poor taste,which adverse the sensory evaluation.FD and FD+MVD could maximally retain the number of probiotics,which maintained at more than 109CFU/g.However,the products dried by FD showed white color and lower hardness which resulted in poor sensory quality.In addition,the drying time was up to 32 h,energy consumption was higher and production efficiency was lower.FD+MVD samples showed higher retention of vitamin C,?-carotene content,which were 71.08%and 95.85%of FD samples,suitable texture,better sensory evaluation.Besides,the energy consumption was lowest and the drying time was shorter.Based on the results above,FD+MVD was selected as the suitable drying process for the enrichment of probiotics.3.In the process of storage,the number of probiotics,?-carotene content,a*and b*decreased,but L*and ?E increased.The number of probiotics stored at 4 ? were more than stored at 25 ?.Compared with stored at 25 ?,the survival rate of probiotics in the simulated gastro-intestinal conditions stored at 4 ? were higher before 30 days and decreased after 45 days,the color changed smaller,the retention rate of ?-carotene(85.4%)was 3 times the group of 25 ? and the sensory quality was better.Nitrogen had little effect on the number of probiotics and the survival rate of the bacteria in the simulated gastro-intestinal conditions before 45 days,but the survival rate was higher after 45 days with nitrogen filled packaging,which could slow down the decline rate of ?-carotene.The ?E of the products was 14.49 when storing for 90 days with nitrogen filled packaging,resulted in lower color deterioration degree,whose sensory quality was better.