Cow’s milk has been part of human diet for a long time. However, raw milk has been associated with various foodborne outbreaks particularly due to bacterial pathogens. Microorganisms in milk are originated from the udder of cattle and as a result of contamination from inadequately cleaned and sanitized teat, milking equipment, air, soil, or workers. Milk obtained under hygienic conditions generally has microorganisms in the range of 103-104 CFU/ml, while that obtained under less hygienic may contain >106 CFU/ml. Raw milk generally contains psychrotrophic, thermoduric and thermophilic microorganisms and occasionally contains pathogens. A survey on raw milk samples from 248 dairy farmers in Pennsylvania, US, found Campylobacter jejuni in 2% of the samples, Shiga toxin producing Escherichia coli (STEC) in 2.4%, Listeria monocytogenes in 2.8%, Salmonella in 6%, and Yersinia enterocolitica in 1.2% samples; while 12% of the samples contained more than one pathogen. Despite the fact that pasteurization has improved the safety of milk; various countries still allow the distribution of raw milk under strict requirements. A 13-year study in the US reported 121 milk-related outbreaks with known food sources and etiological agents. Although pasteurized milk could cause outbreaks, a higher percentage (60%) of the outbreaks was caused by unpasteurized milk and cheese. A higher milk-borne outbreak rate (75%) also occurred in the US states that allow distribution of raw milk to the retail level. The study also suggested that the most predominant etiologic agent in nonpasteurized milk outbreaks was Campylobacter spp while those in pasteurized milk outbreaks was Norovirus. Raw milk consumption should be avoided when there is no confidence on the herds’ and/or farm supervision.
Susu adalah cairan bergizi berwarna putih yang dihasilkan oleh kelenjar susu mamalia. Sejarah mencatat bahwa manusia di Eropa Tengah telah mengonsumsi susu sapi sejak ribuan tahun yang lalu. Pada 4000 tahun sebelum Masehi telah ditemukan bukti-bukti bahwa manusia memerah susu sapi. Dengan 3.25% protein, 4.2% lemak, 4.6% laktosa, 0.65% mineral dan 87.3% air, susu sapi termasuk bahan pangan yang lengkap kandungan gizinya. Akan tetapi kandungan gizi tersebut, ditambah faktor-faktor lainnya, juga sangat mendukung pertumbuhan mikroorganisme termasuk bakteri patogen, sehingga konsumsi susu segar (mentah) telah dihubungkan dengan berbagai outbreak penyakit bawaan pangan. Proses pasteurisasi yang dikembangkan oleh Louis Pasteur pada 1822-1895 berhasil meningkatkan keamanan mikrobiologi susu, akan tetapi proses ini pun harus dikendalikan dengan baik agar tidak terjadi kontaminasi pasca pasteurisasi.
Oleh: Prof. Ratih Dewanti-Hariyadi
Profesor Mikrobiologi Pangan Departemen Ilmu dan Teknologi Pangan
Peneliti SEAFAST Center, Institut Pertanian Bogor
Selengkapnya artikel ini dapat dibaca di majalah FOODREVIEW INDONESIA edisi Juni 2015, yang dapat diunduh di www.foodreview.co.id