甜味種楊桃醃漬發酵過程中醃漬液菌相及成分變化之研究

Studies on Changes in Microflora and Chemical Constituents of Sweet Carambola Pickling Brine during Fermentation

曾美芳(Mei-Fang Tseng)

指導教授 ： 許明仁

國立臺灣大學/生物資源暨農學院/園藝學研究所/碩士(2004年)

https://doi.org/10.6342/NTU.2004.01660

摘要

臺灣種植楊桃品種可分為酸味種及甜味種，甜味種主供生食用，酸味種則供加工用，近年來受農村人力老化，生產成本增加影響，酸味種栽培面積逐年減少，楊桃汁的加工勢必改以甜楊桃發酵生產。
　　以不同鹽度醃漬甜楊桃所得之醃漬液其可溶性固形物及總糖在發酵過程中皆呈下降趨勢，可滴定酸度則由0.15％上升至0.35％，pH值在第一週明顯下降，即無顯著變化。甲醛態氮含量在第一週明顯下降，但第二週回升後即維持穩定之含量。不同醃漬處理醃漬液之抗壞血酸含量在第一週皆明顯降低，發酵初、中期醃漬液中抗壞血酸有微幅波動現象，但到後期則呈現下降趨勢。以不同鹽度處理甜楊桃，91天後醃漬液之Hunter’s L、a、b值有顯著差異，但以肉眼觀察則不易分辨，整體色澤良好。
　　以7% 食鹽醃漬甜楊桃60天後之醃漬液共鑑定出十四種揮發性成分，其中碳氫化合物一種 (tetradecane)、醇類三種 (ethanol, isoamyl alcohol, nonanol)、醛類一種 (nonanal)、酯類九種 (ethyl acetate, isoamyl acetate, ethyl hexanoate, ethyl heptanoate, ethyl octanoate, ethyl nonanoate, ethyl decanoate, ethyl dodecanoate)、酮類一種 (β-ionone)。
　　不同醃漬處理甜楊桃其醃漬液之總生菌約介於2.70×106 ~ 6.50×107CFU/mL，酵母菌數維持在4.03×106 ~ 3.13×107CFU/mL，菌數於醃漬期間變化不大。酵母菌是主要參與甜楊桃汁發酵之菌種，以7%食鹽醃漬甜楊桃所得醃漬液中所篩選出發酵菌株，經分離、純化後以API ID 32C鑑定，鑑定出二屬六株酵母菌 (Candia krusei, Candida magnoliae, Candida pelliculosa, Canidia valida, Kloeckera apiculata, Candida guilliermondii) 參與作用。乳酸菌僅在5%食鹽醃漬甜楊桃之發酵初期參與反應，醃漬第28天後則無法分離出乳酸菌，所分離出之乳酸菌經API 50 CHL鑑定為Lactobacillus plantarum。

關鍵字

總糖 ； 乳酸菌 ； 甲醛態氮 ； 酵母菌 ； 揮發性成分

並列摘要

The carambola cultivars planted in Taiwan can be divided into tart cultivars and sweet cultivars. Sweet cultivars are eaten fresh while tart cultivars are used for food processing. Recently, due to the aging manpower of village and the increase in production cost, the carambola planting acreage of tart cultivars has decreased by year, the processing of carambola juice will eventually using the fermented sweet carambolas as raw material.
The result of this study showed that, the total soluble solids and total sugars decreased as fermentation proceeded; the titratable acidity significantly increased in the first week and then no prominent change throughout the fermentation; the formol nitrogen decreased dramatically in the first week but rose immediately in the second week and had no significant change afterward; the contents ascorbic acid decreased significantly in the first week and at the end of fermentation. Although the Hunter’s L, a, b values showed significantly different among the samples of different salt treatments after 91 days of fermentation, no visual difference in color among the samples was observed.
Fourteen volatile compounds were identified from the pickling brine samples with 7% NaCl treatment for 60 days, among which are: one hydrocarbon (tetradecane)、three alcohols (ethanol, isoamyl alcohol, nonanol)、one aldehyde (nonanal)、nine esters (ethyl acetate, isoamyl acetate, ethyl hexanoate, ethyl heptanoate, ethyl octanoate, ethyl nonanoate, ethyl decanoate, ethyl dodecanoate) and one ketone (β-ionone).
The total bacteria counts for the samples obtained from all treatments throughout the curing period ranged from 2.70×106 to 6.50×107CFU/mL, and the yeast counts ranged from 4.03×106 to 3.13×107CFU/mL. Yeast was identified as the major microorganism responsible for the fermentation of salted sweet carambola. Microbiological studies of colonies isolated from 7% NaCl treated brine were identified by API ID 32C. Two genus with 6 species of yeast (Candida krusei, Candida magnoliae, Candida pelliculosa, Candida valida, Kloeckera apiculata, Candida guilliermondii) were identified throughout the salted sweet carambola fermentation process. Lactic acid bacteria was found only in the early stage of sweet carambola fermentation with 5% NaCl treatment. No lactic acid bacteria was found after 28 days of fermentation. The only lactic acid bacteria identified from the brine samples of sweet carambola fermentation by API 50 CHL was Lactobacillus plantarum.

並列關鍵字

total sugars ； formol nitrogen ； lactic acid bacteria ； volatile compounds ； yeast

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