Sains Malaysiana 41(3)(2012): 325–331

Penilaian Kaedah Pengiraan Escherichia colidalam Masakan Ayam

(Evaluation of Escherichia coli Enumeration Methods in Poultry Dishes)

Ratna Dewi Abdul Rahman & Norrakiah Abdullah Sani*

Program Sains Makanan, Pusat Pengajian Sains Kimia dan Teknologi Makanan

Fakulti Sains dan Teknologi, Universiti Kebangsaan Malaysia

43600 Bangi, Selangor D.E. Malaysia

Abdul Aziz Jemain

Program Statistik, Pusat Pengajian Sains Matematik, Fakulti Sains dan Teknologi

Universiti Kebangsaan Malaysia 43600 Bangi, Selangor D.E. Malaysia

Received: 21 Julai 2011 / Accepted: 19 September 2011

ABSTRAK

Kajian ini bertujuan untuk memilih kaedah terbaik daripada sebelas kaedah pengiraan Escherichia coli dalam masakan ayam. Kaedah-kaedah tersebut adalah piring curahan, piring sebaran, piring titisan, PetrifilmTM, tiga jenis pemiringan terus dan empat jenis kaedah bilangan paling mungkin (MPN). Perbandingan kaedah dijalankan mengikut prosedur ISO 16140. Setiap strain E. coli (ATCC 25922, IMR 1/3 107B dan IMR E243) telah diinokulasikan ke dalam lima jenis masakan ayam bagi mendapatkan kepekatan bakteria sehingga 105 cfu/g. Perlakuan haba dibuat pada 55^oC selama 4-6 min bagi mewujudkan persekitaran yang seakan-akan sama seperti makanan tersebut dihidangkan sebaik sahaja selepas dimasak. Analisis statistik Regressi Kaedah Kuasa Dua Terkecil (KKDT) dijalankan bagi membandingkan sebelas kaedah pengiraan E. coli. Nilai kecerunan (m) yang signifikan (p < 0.05) pada kesemua Graf KKDT membawa maksud kesemua kaedah adalah serupa daripada segi kejituan, korelasi, dan ketepatan relatif. Oleh itu, penilaian praktikal turut dipertimbangkan bagi menentukan tiga kaedah terbaik bagi pengiraan E. coli dalam masakan ayam. Piring curahan, PetrifilmTM dan piring titisan adalah lebih praktikal berbanding lapan kaedah yang lain.

Kata kunci: Escherichia coli; kaedah ISO 16140; masakan ayam; regresi KKDT

ABSTRACT

The purpose of this study was to select the best from eleven methods for Escherichia coli enumeration in poultry dishes. The methods were pour, spread and drop platig, PetrifilmTM, three types of direct plating and four types of most probable number (MPN) methods. Method comparison was carried out based on ISO 16140 procedure. Each type of E. coli strains (ATCC 25922, IMR 1/3 107B and IMR E243) were inoculated into five types of poultry dishes to obtain 105 cfu/g bacterial concentration. Heat treatment was done at 55oC for 4-6 min to mimic the environment as these foods were served right after cooking. The Ordinary Least-Squares (OLS) Regression statistical analysis was carried out to compare eleven methods for E. coli enumeration. The significance (p<0.05) of gradient value (m) for all OLS Graphs mean that all methods were similar in term of accuracy, correlation and relative accuracy. Thus, practical approaches were also considered in order to select the best from eleven methods for E. coli enumeration in poultry dishes. Pour plating, drop plating and PetrifilmTM methods were more practical than the other eight methods evaluated.

Keywords: Escherichia coli; ISO 16140 method; poultry dishes; OLS regression

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*Corresponding author; email: norrra@ukm.my