Preparation Of Lactobacillus Starter And Its Fermented Carrot Powder By Spray Drying

This paper aims to employ the spray drying technology to prepare a highly active Lactobacillus plantarum NCU116 starter culture,and the resulting starter culture was used in fermentation of carrot beverage.Finally,the condition for fermentation of carrot beverage was optimized and the fermented beverage was used to prepare powder by spray drying.By selection of protective agent and optimization of spray drying conditions,it was found that the best formulation of protective agent was 5%(w/w)skim milk,5%(w/w)trehalose and 3%(w/w)monosodium glutamate,the optimum spray drying conditions were inlet temperature,material flow and microbial contents of125?,320 m L/h,10.25 Log cfu/m L,respectively.In the condition,the survival rate of bacteria in the agent after spray drying was above 89.95%,and number of viable count of L.plantarum NCU116 was above 1.0×10¹¹ cfu/g.The water content,hygroscopicity,microstructure,glass transition temperature(Tg),storage stability and the fermentation characteristics of the starter culture produced with different protective agent was tested.Results showed that the moisture of the powder was lower than 4.3%,the hygroscopicity was between 8%and 14%,by observation of microstructure of the powder,it was found that embedding function on the bacteria was good,the surface was smooth,no cracks and fracture.The Tg was measured by differential scanning calorimetric,it was found that various protective agent show different Tg,but all the spray drying powder was in the glassy state at room temperature.When stored the starter culture under-20,4,25,37?one year,the results showed that protective agent and storage temperature in the process all have effect on the viability of NCU116.The protective effect of skim milk and sodium glutamate were better than trehalose and maltodextrin during storage.when the storage temperature was lower than 4?,the viable count keep stable and the effect of temperature was not significant.However,when it was greater than 4?,the temperature has a significant effect on the stability of the NCU116.Based on the research of the fermentation characteristics,it shows that in the process of storage,the activity of starter cultures was gradually decrease,when the temperature was below 4?,the starter was relatively stable,but when the temperature was higher than 4?,the NCU116 fermentation activity decline rapidly.By detecting the cell membrane integrity of spray drying cells and effect of rehydration temperature on the viable count of starter culture,it found that spray drying has serious damage on the cell membrane,the addition of protective agent can improve the integrity of the cell membrane.The skim milk and sodium glutamate provided good protection on cell membrane.After dissolved the starter culture in different temperature,significant difference was found in bacterial survival rate.It showed that the spray drying cause a phase transition of the cell membrane,the protective agent can reduce the phase transition temperature(Tm)of the cell membrane.Preparation of carrot fermentation drinks using spray dried NCU116,through the optimization of fermentation conditions and the spray drying conditions,produce fermented carrot powder that contain viable probiotic.Best fermentation condition is:the carrot jam 25%(w/w),fructose syrup 2%(w/w),and fermentation time 18 h.Optimum spray drying conditions as follows:the carrier was 10%of maltodextrin and5%of disaccharides or oligosaccharides,inlet air temperature 115?,45%gas flow,material flow 320 m L/h,the viable count was greater than 10⁹ cfu/g.By comparing the carrot powder with different carriers,it was found that the drink with 10%(w/w)of maltdextrin and 5%(w/w)trehalose or lactose as carriers have higher sensory traits,good flavor,taste delicious,bright color,mellow aroma.