市售包裝果汁標示及維生素C之含量探討

果汁中抗壞血酸的含量取決於許多變量，像是原料（例如栽培品種、衛生條件、氣候），加工條件（例如加熱、氧化、金屬的存在、pH），儲存環境和添加的抗氧化劑。這些變量(因素)最終也影響了實際上真正由蔬果汁中得到有效維生素C的因素之一。經由流行病學的研究多攝取維生素C可以抗氧化及輔助許多生理功能，維生素C（抗壞血酸）是水果和蔬菜中最重要的維生素，本研究目的是以市售便利商店的包裝果汁為例，分別挑選20種百分百天然非濃縮還果汁，百分百濃縮還原果汁及營養標示含有維生素C，但非百分百濃縮還原的果汁藉由高效能液相層析儀(HPLC)連接紫外光-可見光偵檢器(UV-detector)分析市售包裝果汁標示及維生素C之含量。此方法之intra-day 及 inter-day 之R.S.D.值均小於 5%，Recovery之檢測在80%〜120%之間，顯示具有良好之精密度及準確度。研究結果顯示20種果汁中，營養標示含維生素C的有9種，其測得濃度大部分高於標示濃度；營養標示未含維生素C的有11種，有3種測得維生素C含量，推測應該有額外添加維生素C。

關鍵字

抗壞血酸；抗氧化劑；濃縮還原果汁；高效能液相層析儀

並列摘要

The amount of ascorbic acid in the juice depends on many variables such as raw materials (eg cultivars, hygienic conditions, climate), processing conditions (eg heating, oxidation, presence of metals, pH), storage environment and added antioxidants. These variables (factors) ultimately also affect one of the factors that actually lead to effective vitamin C in vegetable juices. Through the epidemiological research, more intake of vitamin C can resist oxidation and assist many physiological functions. Vitamin C (ascorbic acid) is the most important vitamin in fruits and vegetables. The purpose of this study is to use the packaged juice of a commercial convenience store as an example. Select 20 kinds of 100% natural non-concentrated fruit juice, 100% concentrated fruit juice and nutrient label containing vitamin C but not 100% concentrated fruit juice by high performance liquid chromatography (HPLC) to connect UV-Vis The UV-detector analyzes the commercial packaged juice label and vitamin C content. The intra-day and inter-day R.S.D. values of this method are all less than 5%, and the detection of Recovery is between 80% and 120%, showing good precision and accuracy. The results showed that among the 20 kinds of fruit juices, there were 9 kinds of nutrient-labeled vitamin C, and the measured concentrations were mostly higher than the labeled concentration. There were 11 kinds of nutrient labels without vitamin C, and 3 kinds of vitamin C content were measured. There should be an extra vitamin C added.