• 作者： 鄭丹楓; 張為憲; 張粲如
• 作者服務機構： 國立臺灣大學食品科技研究所; 臺灣省臺北區農業改良場
• 中文摘要： 臺灣目前所栽植之甜菊，大多是以乾燥方式處理後外銷日本，很少新鮮採收即加工製造成甜菊糖。為了提高農民收益、確保甜菊糖含量及品質、增加單位面積生產價值，以便商業化大量生產甜菊糖，故針對甜菊採收後乾燥處理方式及邇後貯藏溫度與時聞，加以探討。結果發現採收後採用風乾方式，緩慢使水分含量降至 15～20%,以下者，總甜菊糖含量及 Stevioside 與 Re-baudioside A 各成分含量均有明顯的降低，其下降比率可達原有總甜菊糖含量之36%，邇後置於 4°C 與室溫下貯藏兩個月期問之變化不大。若以 70°C 烘乾或日曬乾燥法，迅速加以乾燥至水分含量達15%以下，則在乾燥過程中及邇後貯藏期之甜菊糖含量可保持穩定，至於貯藏溫度，在4°C與室溫之問，幾無差異。由此可知甜菊採收期，除了考慮季節因素外，對於當時之氣候條件亦需特別注意，以晴天採收後日曬乾燥為宜，若遇長期陰雨季節時，則需考慮人工乾燥，以70°C或以上之高溫乾燥為佳，而應盡量避免低溫緩慢乾燥與延長高水分含量之時間，同時應避免將乾燥甜菊置於潮濕處貯藏。又為了抑制採收後甜菊中所含酵素之活性，以免破壞甜菊糖成分，試以殺菁法處理，試驗之結果顯示，總甜菊糖含量在殺菁過程中嚴重的降低，其降低比率可達 10～20%,，故殺菁處理不適用於新鮮甜菊之乾燥前處理。
• 英文摘要： Stevia grown in Taiwan is, at present, mostlydried and exported to Japan and scarcely usedfresh for extraction and purification of ste-viosides by local manufacturers. In order tofind the best processes for maintaining thequality and steviosides contents, and thereby toincrease the profit of farmers, we engaged inthis study. From this study we found that if harvestedStevia was dried in air for 4-7 days to a mois-ture content of 15-20%，there was a seriousdecrease in the contents of stevioside and re-baudioside A, which amounted to 36% of theoriginal total steviosides content. However,there was little change in steviosides contentduring the subsequent storage of the dried Steviaeither at 4°C or at room temperature. If theharvested Stevia was rapidly dried to a moisturecontent of 15-20% in an oven at 70°C or bysun drying, there was little change in the con-tents of stevioside and rebaudioside A duringboth the drying process and the subsequentstorage at either 4°C or room temperature. It is therefore concluded that besides theseasonal condition, the climate condition forharvesting the Stevia must also be considered. It is best to harvest Stevia on a sunny day anddry it in sun shine, but in a rainy season, theharvested Stevia must be dried in an oven keptat or above 70°C in order to avoid long timeperiod under high moisture content duringdrying. It is also important to keep dry duringthe subsequent storage. Blanching of the bar-vested Stevia to kill enzymes was found notsuitable as a pre-drying treatment of Stevia,because the total steviosides content was foundto decrease as much as 10-20% during theblanching process.
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