Pencirian Bakteria Asid Laktik dan Sebatian Aroma Ikan Pekasam

Wei Chi Tan, Seng Joe Lim, Wan Aida Wan Mustapha
2017 Sains Malaysiana  
ABSTRAK Dalam kajian ini, bakteria asid laktik (LAB) serta sebatian aroma ikan pekasam daripada spesies yang berbeza ditentukan. Persampelan ikan pekasam iaitu tilapia, loma, lampam, sepat dan gelama diperoleh daripada pembekal Perusahaan Ikan Pekasam Kiah di Kuala Kangsar, Perak. Penentuan spesies LAB dijalankan melalui kaedah pencairan bersiri, pengkulturan LAB, ujian katalase, ujian pewarnaan spora serta ujian pengesanan Gram bakteria dan morfologi. Pengesahan spesies LAB dijalankan melalui
more » ... engekstrakan asid deoksiribonukleik (DNA), amplifikasi dengan tindak balas rantaian polimerasi (PCR), analisis elektroforesis gel dan penjujukan DNA. Hasil jujukan DNA yang diperoleh dibandingkan dengan jujukan dalam pangkalan data GenBank di NCBI menggunakan BLAST. Didapati Lactobacillus brevis KB290 DNA dan Lactobacillus casei W56 wujud dalam pekasam tilapia, Lactobacillus plantarum 16 dalam pekasam lampam, Lactobacillus casei BD-II kromosom dan Lactobacillus plantarum WCFS1 dalam pekasam sepat, Corynebacterium vitaeruminis DSM 20294 dan Streptococcus anginosus C1051 dalam pekasam gelama. Manakala Staphylococcus carnosus subsp. carnosus TM300 kromosom adalah LAB dominan dalam pekasam loma. Sementara itu, sebatian aroma ditentukan melalui kaedah pengekstrakan cecair menggunakan pelarut metanol dan heksana. Pemprofilan sebatian aroma dijalankan dengan kromatografi gas-spektometer jisim (GC-MS). Sebatian aroma dalam ekstrak metanol dan heksana daripada lima jenis ikan pekasam dibandingkan. Bilangan sebatian aroma yang diekstrak menggunakan metanol adalah lebih banyak berbanding dengan yang menggunakan heksana. Sebatian aroma yang paling banyak dikesan adalah daripada pekasam loma. Asid karboksilik merupakan sebatian yang paling dominan dalam ikan pekasam dan memberi bau hamis serta tengik. Kata kunci: Bakteria asid laktik; ikan pekasam; sebatian aroma ABSTRACT In this research, lactic acid bacteria (LAB) and aromatic compounds on different species of pekasam were determined. The sampling of pekasam which were tilapia, loma, lampam, sepat and gelama performed at Kiah Pekasam Enterprise at Kuala Kangsar, Perak. Several procedures were performed to determine the LAB, namely, serial dilution, pour plating, enumeration of LAB, catalase test, Gram-staining and determination of LAB morphology. Confirmation of LAB was carried out which were deoxyribonucleic acid (DNA) extraction, amplification of polymerization chain reaction (PCR), gel electrophoresis and DNA sequencing. The DNA sequence for each strain was matched to the available sequence from GenBank database via BLAST at NCBI. Lactobacillus brevis KB290 DNA and Lactobacillus casei W56 were found on pekasam tilapia, Lactobacillus plantarum 16 was on pekasam lampam, Lactobacillus casei BD-II chromosome and Lactobacillus plantarum WCFS1 were on pekasam sepat, Corynebacterium vitaeruminis DSM 20294 and Streptococcus anginosus C1051 were found on pekasam gelama. Staphylococcus carnosus subsp. carnosus TM300 chromosome was the dominant LAB on pekasam loma. Liquid extraction was carried out to determine the aromatic compounds in pekasam, followed by profiling using gas chromatography-mass spectrometer (GC-MS). Comparison of aromatic compounds between methanol and hexane extracts from five different species of pekasam was performed. Our findings indicated that the methanol extraction was more efficient compared to that of hexane, as the quantity of aromatic compounds in methanol extract was higher to those using hexane. The highest amount of aromatic compounds produced was from pekasam loma. Carboxylic acids were the most dominant compounds found on pekasam and it gave rancid and 'goaty' off-flavour. Keywords: Aromatic compounds; asid lactic bacteria; fermented fish pekasam PENGENALAN Protein adalah makronutrien yang penting untuk tumbesaran. Kekurangan pengambilan protein akan menyebabkan perkembangan terbantut. Lebih daripada 70% kanak-kanak adalah dalam keadaan malnutrisi dan sebanyak satu per empat daripada kanak-kanak berusia lima tahun ke bawah mengalami pertumbuhan terbantut (Lee 2014). Salah satu sumber protein haiwan yang penting di negara-negara Asia Tenggara ialah ikan. Namun, harga ikan segar adalah tinggi dan bekalannya terhad. Dengan memproses ikan kepada pekasam, kualiti produk ikan dapat dikekalkan dan hayat simpanannya
doi:10.17576/jsm-2017-4603-11 fatcat:fy4agtwnqnch7av6g3u7snnq7u