| Abstract: | 殺菁係蔬果加工過程中重要的環節，其目的為失活微生物與酵素。傳統加工係利用熱水進行殺菁來達成酵素失活 ， 但加熱會造成營養成分降解等不良影響。本篇研究旨在應用介電質放電(Dielectric barrier discharge, DBD)電漿用於切片蘋果及切片香蕉之多酚氧化酶(Polyphenol oxidase, PPO)失活。電漿操作條件為頻率60 Hz、電壓20 kV、電極間距2 cm、工作氣體為空氣(500 sccm)以及測試時間(正反面各5〜15分鐘)，並評估電漿處理後對樣品品質之影響。分別探討溫度變化、水分散失、質地、顏色及維生素C等。另外熱水處理條件為65℃測試時間(5〜15分鐘)，評估酵素失活及品質變化。最後把電漿與加熱方法進行比較。
實驗結果顯示，電漿處理時間增加能提升酵素失活，處理15分鐘，切片蘋果之PPO下降 87%，切片香蕉之PPO下降48%。電漿處理前後溫度無顯著上升，質地無顯著變化。熱水處理可在短時間內使切片蘋果與切片香蕉之酵素快速失活，但熱水處理後質地、維生素C與儲藏顏色變化皆大於電漿處理；未來電漿可望應用於切片水果之PPO失活進而達到抑制酵素型褐變之目的。
Blanching is important in freshly fruits processing. The purposes of blanching were to inactivate microorganism and the activity of enzyme existed in fruits. The traditional method for inactivating enzyme activity is blanching fruits using hot water. However, this leads to quality deterioration in nutritional components. The objective of this study was to evaluate using dielectric barrier discharge(DBD) for inactivation polyphenol oxidase(PPO) in sliced apple and banana. The process parameters considered were frequency at 60 Hz, voltage at 20 kV, electrode spacing at 2 cm, using air as working gas (500 sccm), plasma exposure time for 10, 20, and 30 min. The influences of plasma treatment were evaluated through determining the enzyme activity, surface temperature, weight loss, texture, color, and the content of vitamin C.
The parameters for hot water treatment were set at 65℃, treatment for 5, 10, and 15 min. The influences of hot water treatment on enzyme activity and quality parameters were compared with those of plasma treatment. The results showed the enzyme activity decreased in sliced apple and banana, the percentage for inactivation by plasma treatment were 87% and 48%, respectively.
Enzyme activity decreased significantly by short time treatment of hot water. However, the texture parameters, vitamin C, and color were also dramatically changed during storage compared with plasma treatment.
The DBD plasma is expected to be applicable for inactivation of PPO in fresh cut fruit which prevents enzymatic browning. |
