| Vegetables which play an important role on reasonably food structure are the main sources of the vitamins, dietary fiber, minerals and other nutrition components. However, vegetables are a form of perishable product that makes it difficult to store for long time under normal environmental conditional while being able to maintain to their primary quality. At the same time, they would not be able to get a high added value if only sold as fresh vegetables. Therefore, in order to increase the diversity of its derived products and improve its added value, this study used Salicornia bigelovii Torr. and wild cabbage as the main raw material to make as vegetables chips respectively, which undergo re-structuring, addition of seasonings, drying, and other processes.In order to get the best formula of re-structured vegetable chips, the orthogonal and response surface optimization methods (RSM) were used. Orthogonal test the adding amount of seasoning, which used the value of sensory evaluation, and chips' crispiness as the indexes. The result showed that the best formula of the Salicornia bigelovii Torr. chips was as follow: Salicornia bigelovii Torr.70g, carrots 7g, white sesame seeds 2.5g, monosodium glutamate, 0.05g, glutinous rice starch 10g, sugar 3.5g, and peanut protein powder 5g. RSM optimized the adding amount of glutinous rice starch and other materials which used the integrated value of the degree of sensory evaluation, color and chips' crispiness as the response value, and obtained the best formula of the wild cabbage chips that was as follow:wild cabbage,70g; carrots,7.5g; black sesame seeds 3g; glucose,3g; glutinous rice starch,9.6g; sucrose,3.6g; peanut protein powder,4.5g.In order to study different drying conditions on Salicornia bigelovii Torr. chips'quality, hot air drying (AD), vacuum drying (VMD), vacuum microwave drying (MVD) were used. The effect of AD temperature, VD temperature and vacuum pressure, MVD vacuum pressure, microwave power level, and mass loads to crispiness, color, rehydration, sensory evaluation Vc/chlorophyll retention ratio and other indexes of products were investigated. Results showed that AD products at 80℃got better product quality. While for the VD process,70℃,-0.09MPa was the optimum condition. For the MVD process, the best quality products were obtained at-0.07MPa,2.0W/g, and mass loads were 100g.In order to improve the quality of Salicornia bigelovii Torr.chips, MVD-VD combined drying was used. In order to determine the MVD-VD combined drying process conditions, RSM was used. In the optimizated test, power level of MVD, the water transform point and VD temperature were used as factors, and integrated value of drying rate, sensory value, Vc retention ratio crispiness, L* value was used as the response value. The result showed the optimal processing parameters were MVD power level which was at 2.1W/g, water transform point was 18.5%, VD temperature was 72 "C.The result of comparing MVD-VD with separate MVD, VD showed that crispiness, color, Vc and chlorophyll preservation rate, rehydration and other indicators of products by MVD-VD were similar to that of products by MVD, the sensory score of products by MVD-VD was more optimal than products by MVD. The drying time of MVD-VD was shorter than VD for about 1.5h. The Vc and chlorophyll retention ratio of products by MVD-VD were higher than products by VD for about 23.4% and 25.3% respective.In order to find a suitable drying method for wild cabbage chips, microwave vacuum freeze drying (MFD), AD, and MVD were used. The affect of different drying condition on crispiness, color, rehydration, sensory evaluation and other indexes of products were investigated. Results showed that drying time of MVD was the shortest which just need 30min and the second was MFD which need 300min. Quality of MFD products was the most desirable, while AD product was the least desirable one. For MFD products, the Vc retention ratio reach to 81.7% and peak value of sensory assessment was 0.425, which was the highest. |
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