結合康普茶與乳酸菌開發新型新鮮起司

Abstract

自2025年起，紐西蘭牛奶輸入將實施零關稅，可能對臺灣乳業造成衝擊。發展具在地特色與附加價值之風味型乳品有其必要性。康普茶菌群具多樣代謝潛力，應用於起司製程可望增添功能性與風味層次，其微生物組成及發酵特性須先釐清，並需補充乳酸菌以利發酵控制。本研究分為三大部分。第一部分為商業康普茶樣品中微生物菌株之分離與鑑定，採用16S rRNA與ITS定序技術，分離出三株醋酸菌 (Acetobacter tropicalis、Gluconobacter potus、Komagataeibacter intermedius) 與五株酵母菌 (Brettanomyces bruxellensis、Hanseniaspora valbyensis、Saccharomyces cerevisiae、Starmerella davenportii、Zygosaccharomyces kombuchaensis)。進一步評估醋酸菌之酵素活性，結果顯示三菌株皆具中等以上酯解酶與酯解脂肪酶活性。酵母菌則測定其醣類利用能力，結果顯示除H. valbyensis外皆可利用 D-葡萄糖，S. cerevisiae對多種醣類具微弱利用能力。第二部分探討康普茶發酵過程，以臺茶18號紅茶為基底，於26 °C下發酵七天，pH值由4.21下降至3.48，自第5天起趨於穩定，顯示發酵終點約為第五天。以沒食子酸為標準測定總多酚類含量，結果顯示未發酵紅茶含量為423.25 mg GAE/L，發酵後提升至630.75 mg GAE/L，具顯著差異 (p < 0.05)，顯示康普茶發酵能有效提升茶湯抗氧化潛力。第三部分以康普茶液與 Streptococcus thermophilus、Lactobacillus delbrueckii subsp. bulgaricus混合作為發酵劑進行起司製作，探討菌株間之互動及其對發酵表現之影響。以優格菌和康普茶共同發酵的混合組發酵26小時後pH值降至5.39，顯示乳酸菌仍具良好產酸能力，且未受康普茶菌種干擾。活菌數方面，兩株乳酸菌在發酵過程中均增加；酵母菌與醋酸菌在混合組中亦穩定存活。機能性分析顯示，混合組具最高總多酚含量 (0.76 ± 0.06 mg GAE/g) 與 2,2-Diphenyl-1-picrylhydrazy (DPPH) 自由基清除率 (42.77 ± 3.57%)，顯示共培養可提升起司之抗氧化潛力。惟總多酚含量差異未達統計顯著 (p > 0.05)。質地方面，僅添加康普茶的組別堅實度最高 (159.90 ± 4.96 g，p < 0.05)，混合組相對較低，推測與酸度、醋酸菌酵素活性與細菌纖維素的生成影響結構有關。感官品評方面雖無統計顯著差異 (p > 0.05)，但優格組於香氣、風味及整體接受度得分較高，混合組具有柔軟口感與明顯酸味，水果與茶香表現突出，展現潛在的市場接受性。保存性試驗結果顯示，混合組具較佳之活菌穩定性與持續產酸能力，含水量變化小，保水性良好；且三週內未檢出腸桿菌科與大腸桿菌群，顯示其具有良好之保存穩定性與衛生安全性。綜合而言，康普茶菌群之多樣性與代謝潛力可有效豐富新鮮起司的風味與機能性，並與乳酸菌展現協同發酵效應，提升整體產品價值。本研究首次將康普茶菌株應用於與優格菌共培養的起司製程，顯示其在風味強化、抗氧化潛能及保存穩定性上具發展潛力。未來建議深化菌株功能篩選與代謝產物分析，並結合台灣特色茶葉資源，開發兼具風味、健康機能與文化價值之創新型乳製品，以回應市場對高品質、多元化功能性食品的需求。

According to the Agreement between New Zealand and the Separate Customs Territory of Taiwan, Penghu, Kinmen, and Matsu on Economic Cooperation (ANZTEC), New Zealand’s liquid milk imports will enter Taiwan at zero tariffs starting in 2025, potentially impacting Taiwan’s dairy industry. Therefore, the development of value-added and locally characteristic dairy products is essential. Kombucha microbiota has the potential to enhance the functionality and flavor complexity of cheese; however, its microbial composition and fermentation characteristics must be clarified prior to application. Additionally, the supplementation of lactic acid bacteria is necessary to ensure proper fermentation control. This study is divided into three main parts: The first part focuses on the isolation and identification of microbial strains present in commercial kombucha. Using 16S rRNA and ITS sequencing, we isolated three acetic acid bacteria (Acetobacter tropicalis, Gluconobacter potus, and Komagataeibacter intermedius) and five yeasts (Brettanomyces bruxellensis, Hanseniaspora valbyensis, Saccharomyces cerevisiae, Starmerella davenportii, and Zygosaccharomyces kombuchaensis). Assays revealed that all three acetic acid bacteria exhibit moderate to high esterase and lipase activity. The test indicated that all yeasts except H. valbyensis can utilize D‑glucose, and S. cerevisiae shows weak activity on various sugars. The second part examines the fermentation of kombucha, recording its changes over different fermentation times. Using Taiwan Tea No. 18 red tea at 26 °C over seven days, pH declined from 4.21 to 3.48 and stabilized after day 5, indicating fermentation completion. Total phenolic content increased significantly from 423.25 to 630.75 mg GAE/L post-fermentation (p < 0.05), demonstrating enhanced antioxidant potential. The third part involves mixing kombucha with Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus as a cheese starter culture. Kombucha was mixed with S. thermophilus and L. bulgaricus to produce cheese. The pH value of the mixed group, co-fermented with yogurt cultures and kombucha, decreased to 5.39 after 26 hours of fermentation, confirming lactic acid bacteria retained acidification potency when combined with kombucha microbes. Lactic bacterial counts increased, indicating no inhibitory effects from kombucha microbiota. Yeasts and acetic acid bacteria remained stable or modestly increased. The mixed group exhibited the highest total phenolics (0.76 ± 0.06 mg GAE/g) and DPPH radical-scavenging activity (42.77 ± 3.57%), evidencing improved antioxidant function—though phenolic differences were not statistically significant (p > 0.05). Textural analysis revealed cheese with kombucha alone showed the highest firmness (159.90 ± 4.96 g, p < 0.05), while the combined group was softer, likely influenced by acid levels, acetic acid bacterial enzymes, and bacterial cellulose formation. Sensory evaluation showed no significant differences (p > 0.05), though the yogurt-only group scored highest in aroma, flavor, and overall acceptance; the mixed group achieved good consumer acceptability with fruit-tea aroma. Storage studies revealed the mixed group maintained stable microbial populations, sustained acid production, and minimal moisture loss; no coliforms were detected over three weeks, demonstrating good shelf stability and safety.Kombucha’s microbial diversity and metabolic versatility can effectively enhance the flavor and functionality of fresh cheese, showing synergy with lactic cultures and adding product value. This study is the first to apply kombucha microbiota in a functional fresh cheese system co-cultured with yogurt bacteria, revealing promising improvements in flavor, antioxidant potential, and shelf stability. Future work should focus on screening strain functionality, profiling metabolites, and harnessing Taiwan’s unique tea resources to create cheese products that combine flavor, health benefits, and cultural value, aligning with consumer demand for high-quality, diversified functional dairy foods.