清洗與貯存對狼尾草品質及狼尾草原汁總生菌數與抗氧化性影響之探討

Effect of cleaning and storage on the total count and antioxidant capacity of napiergrass and its juice

本研究以新鮮狼尾草葉片為材料，探討不同清洗處理，包括清洗用水種類、清洗方式、添加洗劑、殺菁時間等，對狼尾草總生菌數、DPPH清除能力、葉綠素與總酚之影響，並進一步評估在不同貯存溫度（25℃、4℃、-18℃）下，狼尾草原汁相關性質之變化。結果顯示，狼尾草清洗效果，在降低總生菌數方面，以自來水手洗後，配合沸水殺菁6秒的方式較佳。經殺菁後所榨得的狼尾草原汁，以低溫（4℃）貯存品質優於室溫（25℃）或冷凍（-18℃）貯存者。其總生菌數在25℃存放12小時後，已超出5 Log CFU／g；低溫者則可存放6天。狼尾草汁的DPPH清除能力則於貯存過程中逐漸下降，並與總酚及葉綠素含量顯著相關，其相關係數各為0.96與0.98。 Effect of washing (cleaning water, cleaning agent, cleaning method and blanching time) on the napiergrass of the total plate count, DPPH scavenging ability, chlorophyll and total phenol were studied. The fresh juice were further investigated for their in storage (25℃, 4℃, -18℃). Results showed that the best way to decrease the total plate count was to clean the samples with the running water and hand washing. Both chlorophyll concentration and DPPH scavenging ability were reduced after washing, and they were positively correlated with coefficient value of 0.92(P＜0.0001). When blanched napiergrass juice was stored under 25℃, the total plate count would exceed 5 Log CFU/g after 12 hours. The chlorophyll decreased dramatically, especially in the blanched sample as compared with the sample without blanching (38.5 mg/L and 229.7 mg/L respectively). The changes of total phenolics and DPPH scavenging ability was similar to chlorophyll.