Antibacterial Activity of Spice Extracts against Food-related Bacteria

食品の微生物制御で重要となる数種の細菌を対象として、17種の香辛料と5種のハーブの抗菌性を試験した。試料にはエタノールで抽出したエキスを用いた。香辛料の抗菌性は全般的にグラム陰性菌よりもグラム陽性菌に対して強かった。とくに、高い耐熱性の芽胞を形成して缶詰のフラットサワー原因菌として問題となる Bacillus stearothermophilns は大部分の香辛料に感受性を示した。なかでも、パプリカはMIC(最小発育限止濃度)が0.005%と最も強い抗菌性を示し、アニス(MIC:0.01%)、メース(MIC:0.02%)がそれに次いだ。これらの抗菌性は基礎培地のpHを弱酸性にしたり、塩分濃度を少し高めることによって強くなり、pH6.0および1.5%NaCl存在下でMICは約1オーダー低下した。しかし、乳酸ナトリウムとの相乗効果はほとんど認められなかった。以上の結果は、寒天希釈法と液体希釈法、接種物として栄養細胞と芽胞、いずれを用いた場合も差はみられなかった。セージは0.1%濃度で Bacillns 属細菌(B. subtilis, B. cereus, B. coagulans)の発育を完全に阻止した。カモミールなどのハーブの抗菌性は比較的低かった。グラム陰性菌について Eseherichia coli と Sainonella はいずれの香辛料でも0.2%濃度で発育阻害はみられず、Vibrio cholerae non-O1がセージ、ホワイトペッパーおよびクローブに感受性を示したのみであった。以上、食品中での耐熱性芽胞形成菌の制御に一部の香辛料が有効である可能性を明らかにした。

The present study was designed to identify spices and herbs that possess antibacterial activity and to apply for control of microorganisms in food. Alcoholic extracts of seventeen spices and five herbs were prepared and examined for growth inhibition of several kinds of food-related bacteria in culture media. Bacillus stearothermophilus, which produces heat-resistant spores, was highly sensitive to most of the spices tested. Both germination of spores and outgrowth of vegetative cells of this organism were inhibited by most of the spices tested. The MICs (minimal inhibitory concentrations) were 0.005% for paprika, 0.01% for anise and 0.02% for mace both on agar and in liquid media. The inhibition of this organism by effective spices was influenced by pH and NaCl concentration of the basal medium. When the pH and NaCl were 6.0 and 1.5%, respectively, the MICs decreased to 10-20%. No synergistic effect of spice and sodium lactate was observed except for mace. At 0.05%, nutmeg, sage, and white pepper perfectly inhibited the growth of this organism. Garlic showed no antibacterial effect and turmeric was also less effective. In general, antibacterial activity of herbs such as chamomile was comparatively low. Against B. coagulans, sage and rosemary inhibited the growth and the MICs were 0.05% and 0.2%, respectively. Both Escherichia coli and Salmonella were not inhibited by 0.2% concentration of all the spices and herbs tested. Sage showed the inhibitory effects against B. subtilis, B. cereus and Staphylococcus aureus. These results suggest that control of the thermophilic bacteria, especially B. stearothermophilus, in canned foods is possible by some spices.