Effect Of Processing On The Quality Of Toona Puree

Toona sinensis is an unique and traditional woody vegetable in China,which was popular with consumers because of its special aroma and high therapeutic value.As a seasonal vegetable,Toona sinensis gradually lignified after April,which was able to seriously affect the taste and nutritional value.Processing can effectively extend the preservation time of Toona sinensis and change the situation that keeping both taste and flavor is impossible.In order to extend the preservation time and maintain its sensory and nutritional qualities,the fresh tender buds were used as raw materials.Toona puree was developed with water blanching and enzymatic treatment.Some significant problems in the process were discussed.The main results were as follows.Toona sinensis of the first growth period had the highest nitrite content,followed by the second and the third growth period.The contents of nitrite in the process of room temperature storage showed a gradually decreasing tendency during storaging.The contents of nitrite in the process of 4 degree storage showed the tendency of first increasing,then decreasing and eventually leveling off.For the treatments using combined methods,soaking in 0.2%sodium carbonate solutions at 40? for 20 min and then blanching in boiling water for 2.5min had the optimal nitrite reducing effects,which also had the color protecting effects.The content of total phenols decreased with prolonging blanching temperature and time.Chlorophylls and color of Toona sinensis were instable to heat.The higher blanching temperature,the faster degradation of chlorophylls.Moderately decreasing blanching temperature and time was favorable for protecting color and chlorophyll.Chlorophylls breakdown and color loss(a·b/L value)followed a first-order reaction with the activation energy(Ea)of 12.586 kJ/mol and 53.351 kJ/mol respectively.Significant correlation between chlorophylls and a·b/L value were found.It was suggested that a·b/L value could evaluate change of color and the chlorophyll content of blanched Toona sinensis.The vitamin C in Toona sinensis was instable to heat and pH value.Blanching temperatures were more effective on the retention of vitamin C than pH values.With the rise of blanching temperature and pH value,the retention rate of vitamin C declined,moreover the degradation of vitamin C followed a first-order reaction with the activation energy(Ea)of 62.022?58.489 and 54.741kJ/mol.Increasing blanching temperature at the same pH value,or raising pH value at the same blanching temperature would increase the degradation rate constant and reduce half-life value of vitamin C.Moderately decreasing blanching temperature and pH value,especially reducing blanching temperature,were favorable for protecting vitamin C.Utilizing enzymatic treatment with cellulase was able to reduce the paticle size and improve the release amount of total phenols in Toona sinensis puree.Soaking in 3% cellulase at 42? for 125 min had the optimum enzymatic treatment effects,which particle size of 706.006 ?m and total phenols of 13.041?g /g could be obtained with.The particle size decreases by 12.30%,and the total phenol content increased by 14.13%.With the optimization of orthogonal experiment,the best recipe was 2g salt,20 mL oil and 0.2g xanthan gum in 100 g toona puree.