AKTIVITAS ANTIMIKROBA MINYAK ESENSIAL JAHE MERAH (Zingiber officinale var. Rubrum) DAN LENGKUAS MERAH (Alpinia purpurata K. Schum) TERHADAP BAKTERI PATOGEN DAN PERUSAK PANGAN

Abstract

The aims of this study was to determine the characteristics, composition and antimicrobial activity of essential oils of local Indonesian red ginger and red galangal against four pathogenic and food spoilage bacteria, which were B.cereus ATCC 10876, E. coli ATCC 25922, S. typhimuriumATCC 14028, and P. aeruginosa ATCC 27853. Analysis of physicochemical characteristics was carried outin accordance with ISO7355:1985. The chemical compositionwas analyzed using aGC-MS. The antimicrobial activity was determined by disc diffusion method and broth microdillution method was used for determine MIC and MBC values. Red ginger essential oil characteristic was brownish yellow, specific gravity 0.883, refractive index 1.480, optical rotation -8.45o, clear soluble (1:1) in 90 % alcohol, 2.06 acid number and 42.45 ester number. Redgalangal essential oil had a characteristic bright yellow color, specific gravity 0.895, refractive index 1.496, optical rotation -9.15o, clear soluble (1:1) in 90 % alcohol, 1.95 acid number and 140.15 ester number. The major component of red ginger essential oils were trimethyl-heptadien-ol, ar-curcumene, camphene, carbaldehyde, -sesquiphellandrene, and nerol; while the major component of red galangal essential oil were 1.8-cineole, chavicol, 9-desoxo-9-xi-hydroxy-3-pentaacetate-3,5,7,8,9,12-Ingol,- caryophyllene and -selinene. The essential oil of red ginger and red galangal hadmoderate antibacterial activity against pathogenic and food spoilage bacteria with the average inhibition zone 7.17-10.33 and 7.25-11.17mm.Red ginger essential oils could inhibit the growth of tested bacteria with MIC values of 2.65-3.97 mg/mL and MBC value of 3.10-5.29 mg/mL, while the red galangal essential oil could inhibit the growth of tested bacteria with MIC values of 1.79-4.03 mg mL and MBC values of 1.79-4.92 mg/mL. Based on the MIC and MBC values,all tested bacteriasensitivity to essential oils of red ginger and galangal red decline in a row B.cereus > E. coli > S. typhimurium> P. aeruginosa. Sensitivity of Gram positive and Gram negative bacteria to both essential oils demonstrate the potential of the oils to be used as a natural preservative in the food industry.Keywords: Antimicrobial, essential oil, red ginger, red galangal ABSTRAKPenelitian ini bertujuan untuk mengetahui karakteristik, komposisi dan aktivitas antimikroba minyak esensial jahe merah dan lengkuas merah lokal Indonesia terhadap empat spesies bakteri patogen dan perusak pangan, yaitu B.cereus ATCC 10876, E.coli ATCC 25922, S. typhimurium ATCC 14028, dan P. aeruginosa ATCC 27853. Analisis karakteristikfisika-kimia dilakukan sesuai standar ISO 7355:1985. Komposisi kimia dianalisis menggunakan alat GC-MS. Pengujian aktivitas antimikroba dilakukan dengan metode difusi cakram untuk menentukan zona hambat, sertabroth microdillution untuk menentukan nilai Minimum Inhibitory Concentration (MIC) dan Minimum Bactericidal Concentration (MBC).Karakteristik minyak esensial jahe merah yang dihasilkan yaitu kuning kecoklatan, berat jenis 0,883, indeks bias 1,480, putaran optik -8.45, larut jernih (1:1) dalam alkohol 90%, bilangan asam 2,06, dan bilangan ester 42,45. Minyak esensial lengkuas merah memiliki karakteristik warna kuning terang, berat jenis 0,895, indeks bias 1,496, putaran optik-9.15, larut jernih (1:1) dalam alkohol 90%, bilangan asam 1,95 dan bilangan ester 140,15. Komponen mayor minyak esensial jahe merah terdiri dari trimethyl-heptadien-ol, ar-curcumene, camphene, carbaldehyde, -sesquiphellandrene, dan nerol; sedangkan komponen mayor minyak esensial lengkuas merah terdiri dari 1.8-cineole, chavicol,9-desoxo9-xi-hydroxy-3,5,7,8,9,12-pentaacetat-ingol, -caryophyllenedan -selinene. Minyak esensial jahe merah dan lengkuas merah memiliki aktivitas antibakteri yang bersifat moderat terhadap bakteri patogen dan perusak pangan, dengan kisaran zona hambat rata-rata 7,17-10,33 mm dan 7,25-11,17 mm. Minyak esensial jahe merah dapat menghambatpertumbuhan bakteri uji pada nilai MIC 2,65-3,97 mg/mL dan nilai MBC 3,10-5,29 mg/mL, sedangkan minyak esensial lengkuas merah dapat menghambat bakteri uji dengan nilai MIC 1,79-4,03 mg/mL dan nilai MBC 1,79-4,92 mg/mL. Berdasarkan nilai MIC dan MBC, sensitivitas bakteri uji terhadap minyak esensial jahe merah dan lengkuas merah menurun berturut-turut dari B. cereus > E. coli > S. typhimurium > P. aeruginosa. Sensitivitas bakteri Gram positif dan Gram negatif terhadap kedua minyak esensial ini menunjukkan potensi minyak esensial jahe merah dan lengkuas merah untuk digunakan sebagai pengawet alami di industri pangan.Kata kunci: Antimikroba, jahe merah, lengkuas merah, minyak esensial