楊桃 (Averrhoa carambola L., 英文名為carambola) 屬酢醬草科 (Oxalidaceae) 五斂子屬 (Averrhoa),為熱帶、亞熱帶之水果,又名星星果。楊桃原產地大致是在馬來半島至摩洛加群島一帶,台灣則為清朝時引進,此時期之品種皆為酸味種,至民國50年代以後,發現優良實生變異後,才開始有商業化的栽培。楊桃果實依酸味強度分為酸味種及甜味種,酸味種味道酸澀,生食口感不佳,但其香氣濃郁,主要供加工之用;甜味種果實甜度高,果實較大,適宜鮮食。但隨市場型態而改變,酸味種楊桃栽培面積日益縮減,農民多改種甜味種楊桃;而傳統楊桃汁之發酵皆以酸楊桃進行醃漬,因此本實驗以酸味種與甜味種楊桃進行鹽漬發酵,探討兩者於醃漬發酵過程中其成分之變化,並評估其抗氧化特性分析與感官品評試驗,討論發酵後兩者之差異。就兩者之果實一般組成成分,以甜味種水分含量、粗蛋白與粗纖維較高;兩者間其灰分與粗脂肪部分則差異不大;而就發酵期間其一般成分變化,酸味種其pH值較甜味種低;可滴定酸部分,酸味種於一週後由 1.0% 降至 0.55% 左右,爾後呈現平穩狀態;甜味種其可滴定酸含量則隨發酵時間而有緩慢上升之趨勢;酸味種之有機酸含量以草酸含量由 1.02% 降至 0.29% ;甜味種則於發酵初期無醋酸生成,但於發酵後期主要之有機酸為醋酸。整體而言,酸味種於一週後完成發酵,爾後為風味物質之熟成;甜味種部分則於約至第九週後仍有成分之變化,微生物發酵仍持續進行;而就抗氧化特性分析部分,則以酸味種楊桃較甜味種具有較佳之抗氧化特性。另外針對自行釀造之楊桃汁進行感官品評其試驗結果得知,與其他市售品牌相比其整體接受度並不高,顯示仍具有改善之空間,可藉由添加其他香料或其他方式加以改善之。
Carambola (Averrhoa carambola L.), a member from family Oxalidaceas, also known as star fruit due to its star-shaped when cut in cross-section. It is originated from Peninsular Malaysia and Mo Muojia Islands and the sour cultivars were introduced to Taiwan during Qing Dynasty. After 1960’s years, commercial cultivation appeared due to improvement on species variation. Carambola can be divided into sour cultivars and sweet cultivars. Sour cultivars are normally used for food processing while sweet cultivars are consumed as fresh fruit. In recent years, the cultivation area of sour cultivars has switched to sweet cultivars. In this study, sour cultivars and sweet cultivars were used for saline fermentation, changes in the composition, antioxidant properties and sensory evaluation were tested and evaluated. The result showed that sweet cultivars have higher moisture content, crude protein and crude fiber, but no significant difference found in the crude ash and crude fat between sour and sweet cultivars. In sour cultivars, pH value decreased in the first week and then no prominent change throughout the fermentation process. The titratable acidity of sour cultivars decreased from 1% to 0.55% within one week and then no prominent change throughout the fermentation; in sweet cultivars, the titratable acidity increased during the fermentation process. Oxalic acid contents decreased from 1.02% to 0.29% in the one week in sour cultivars, and remained in same level on following days. Acetic acid has been observed after pickling for three weeks, in sour cultivars increased from 0.05% and did not change a lot during the fermentation; in sweet cultivars increased from 0.10% to 0.26%. Overall, fermentation of sour cultivars terminated after one week, and starts to aging on the following days. In sweet cultivar, the fermentation takes up to nine weeks. In the antioxidant properties, sour cultivars performed higher in antioxidant capability. Compared with other commercial products, sensory evaluation performed better in overall acceptance.