Efficacy of Different Decontamination Treatments on Microbial Population of Leafy Vegetables (in English)

Abstract

In the present study, levels of microbial contamination on some leafy vegetables collected from local wholesale markets (Ankara, Turkey) were determined. The efficacies of different surface decontamination methods on these vegetables were also investigated. Average total mesophilic aerobic bacteria (MB) and total coliform (TC) counts were between 6.20 - 7.14 log cfu/g, and 3.39 - 4.91 log MPN/g, respectively. Of the sixteen samples analyzed, thirteen contained Escherichia coli. Dipping in tap water was not effective at reducing microbial populations on vegetables. Difference between chlorine (200 mg/L) and acetic acid (0.25 %, v/v) treatments in the reduction of MB and TC counts was found to be statistically insignificant. The highest reduction in both MB and TC counts was obtained by sequential treatment with acetic acid followed by chlorine. According to these results, acetic acid can be an alternative to chlorine for surface decontamination of leafy vegetables in food establishments and house level. Level of microbial decontami­nation can be increased by sequential dipping in different sanitizers.

Keywords

• Leafy vegetable, natural microbial flora, surface decontamination, chlorine, acetic acid

Değişik Dekontaminasyon Yöntemlerinin Yapraklı Sebzelerde Mikrobiyel Yük Üzerine Etkisi (İngilizce)

Abstract

Bu çalışmada, Ankara’daki yerel pazarlardan toplanan bazı yapraklı sebzelerin mikrobiyel kontaminasyon düzeyleri belirlenmiştir. Çeşitli yüzey dekontaminasyon işlemlerinin bu sebzeler üzerindeki etkileri de ay­rıca incelenmiştir. Ortalama toplam mezofilik aerobik bakteri (MB) ve toplam koliform (TC) sayıları sıra­sıyla 6.20 - 7.14 log kob/g ve 3.39 - 4.91 log EMS/g düzeyinde bulunmuştur. İncelenen 16 örneğin 13’ünde Escherichia coli tespit edilmiştir. Çeşme suyuna daldırma işlemi, sebzelerdeki mikrobiyel popülasyonun azaltılmasında etkili bulunmamıştır. MB ve TC sayılarındaki azalma açısından klor (200 mg/L) ve asetik asit (% 0.25, v/v) ile yıkama işlemleri arasında istatistiksel olarak önemli bir fark bulunmamıştır. MB ve TC sayılarındaki en fazla azalma, birbirini takip eden asetik asit ve klor uygulamasıyla elde edilmiştir. Bu sonuçlara göre de asetik asitin gıda işletmelerinde ve ev düzeyinde yapraklı sebzelerin yüzey dekontami­nasyon uygulamalarında klora alternatif olabileceği ortaya çıkmıştır. Mikrobiyel dekontaminasyon düzeyi farklı sanitizerlerin ardışık uygulamaları ile arttırılabilecektir.

Keywords

• Yapraklı sebze, doğal mikrobiyel flora, yüzey dekontaminasyonu, klor, asetik asit.

References

1. . Soriano JM, Rico H, Moltó JC, Mañes J. 2000. Assessment of the microbiological quality of lettuce served in University restaurants. Int J Food Microbiol, 58, 123-8.
2. 2. Vandekinderen I, Van Camp J, Devlieghere F, Veramme K, Denon Q, Ragaert P, De Meulenaer B. 2008.
3. Effect of decontamination agents on the microbial population, sensorial quality, and nutrient content of grated carrots (Daucus carota L.). J Agr Food Chem, 56, 5723- 5731.
4. 3. Behrsing J, Winkler S, Franz P, Premier R. 2000. Efficacy of chlorine for inactivation of Escherichia coli on vegetables. Postharvest Biol Tec, 19, 187–192.
5. 4. Sengun IY, Karapinar M. 2004. Effectiveness of lemon juice, vinegar and their mixture in the elimination of Salmonella typhimurium on carrots (Daucus carota L.). Int J Food Microbiol, 96, 301-305.
6. 5. Nascimento MS, Silva N, Catanozi M, Silva KC. 2003. Effects of different disinfection treatments on the natural microbiota of lettuce. J Food Protect, 66, 1697–1700.
7. 6. Viswanathan P, Kaur R. 2001. Prevalence and growth of pathogens on salad vegetables, fruits and sprouts. Int J Hyg Envir Heal, 23, 205–213.
8. 7. Cordano AM, Jacquet C. 2009. Listeria monocytogenes isolated from vegetable salads sold at supermarkets in Santiago Chile: Prevalence and strain characterization. Int J Food Microbiol, 12, 176–179.

9. 8. Abong’o BO, Momba MNB, Mwambakana JN. 2008. Prevalence and antimicrobial susceptibility of Escherichia coli O157:H7 in vegetables sold in the Amathole district, Eastern Cape Province of South Africa. J Food Protect, 71, 816–819.
10. 9. McMahon MAS, Wilson IG. 2001. The occurence of enteric pathogens and Aeromonas species in organic vegetables. Int J Food Microbiol, 70, 155–162.
11. 10. Rimhanen-Finne R, Niskanen T, Hallanvuo S, Makary P, Haukka K, Pajunen S, Siitonen A, Ristolainen R, Poyry H, Ollgren J, Kuusi M. 2006. Yersinia psudotuberculosis causing a large outbreak associated with carrots in Finland. Epidemiol Infect, 137, 342–347.
12. 11. Szabo EA, Scurrah KJ, Burrows JM. 2000. Survey for psychrotrophic bacterial pathogens in minimally processed lettuce Lett Appl Microbiol, 30, 456–460.
13. 12. Beuchat LR. 2002. Ecological factors influencing survival and growth of human pathogens on raw fruits and vegetables. Microbes Infect, 4, 413–423.
14. 13. Harris L, Farber J, Beuchat L, Parish M, Suslow T, Garrett E, Butsa F. 2003. Outbreaks associated with fresh produce: incidence, growth, and survival of pathogens in fresh and fresh-cut produce. Comp Rev Food Sci F,. 2, 78–141.
15. 14. Karapinar M, Sengun IY. 2007. Antimicrobial effect of koruk (unripe grape – Vitis vinifera) juice against Salmonella Typhimurium on salad vegetables. Food Control, 18, 702–706.
16. 15. Beuchat LR, Nail BV, Adler BB, Clavero MRS. 1998. Efficacy of spray application of chlorine in killing pathogenic bacteria on raw apples, tomatoes, and lettuce. J Food Protect, 61, 1305–1311.
17. 16. Sapers GM. 2001. Efficacy of washing and sanitizing methods for disinfection of fresh fruit and vegetable products. Food Technol Biotech, 39(4), 305–311.
18. 17. Delaquis PJ, Fukumoto LR, Toivonen PMA, Cliff MA. 2004. Implications of wash water chlorination and temperature for the microbiological and sensory properties of fresh-cut iceberg lettuce. Postharvest Biol Tec, 31(1), 81–91.
19. 18. Allende A, Selma MV, López-Gálvez F, Villaescusa R, Gil MI. 2008. Role of commercial sanitizers and washing systems on epiphytic microorganisms and sensory quality of fresh-cut escarole and lettuce, Postharvest Biol Tec, 49, 155-163.
20. 19. Parish M, Beuchat L, Suslow T, Haris L, Garrett E, Farber J, Butsa F. 2003. Methods to reduce/eliminate pathogens from fresh and fresh-cut produce. Comp Rev Food Sci F, 2, 161-173.
21. 20. Keskinen LA, Burke A, Annous BA. 2009. Efficacy of chlorine, acidic electrolyzed water and aqueous chlorine dioxide solutions to decontaminate Escherichia coli O157:H7 from lettuce leaves. Int J Food Microbiol, 132 (2–3), 134–140.
22. 21. Chang JM, Fang TJ. 2007. Survival of Escherichia coli O157:H7 and Salmonella entrica serovar Typhimurium in iceberg lettuce and the antimicrobial effect of rice vinegar against E. coli O157:H7. Food Microbiol, 24, 745–751.
23. 22. Anon 2002. Turkish Standards Institution (TSE) 2002. Water quality - Determination of free chlorine and total chlorine - Part 3: Iodometric titration method. Turkish Standards Institution Publications No. TS 6230 EN ISO 7393-3, Ankara, Turkey.
24. 23. Bett LK. 2002. Evaluating sensory quality of fresh cut fruits and vegetables. In: Fresh Cut Fruits and Vegetables: Science, Technology and Market, L. Olusola (Ed.), CRC Press LLC, New York, pp. 436.
25. 24. Akbas MY, Olmez H. 2007. Inactivation of Escherichia coli and Listeria monocytogenes on iceberg lettuce by dip treatments with organic acids. Lett Appl Microbiol, 44, 619–624.
26. 25. Harrigan W.F. 1998. Laboratory Methods in Food Microbiology. 3rd Edition, Academic Press, San Diego, USA, 532 p.
27. 26. Temiz, A. 2000. Genel Mikrobiyoloji Uygulama Teknikleri. 3. Baskı, Hatiboğlu Yayınevi, Ankara, Türkiye, 291 p.
28. 27. FDA. 2002. BAM: Enumeration of Escherichia coli and the Coliform Bacteria. http://www.fda.gov/food/ scienceresearch/LaboratoryMethods/BacteriologicalAnalyticalManualBAM/ucm064948.htm (Accessed 01 March 2004).
29. 28. Feng PCS, Hartman PA. 1982. Fluorogenic assays for immediate confirmation of Escherichia coli. Appl Environ Microb, 43, 1320-1329.
30. 29. Anonymous, 2005. Merck Gıda Mikrobiyolojisi Uygulamaları. Ed: A.K. Halkman. Başak Matbaacılık Ltd. Şti., Ankara, Türkiye, 358 p.
31. 30. Abadias M, Usall J, Anguera M, Solsona C, Viñas I. 2008. Microbiological quality of fresh, minimally-processed fruit and vegetables, and sprouts from retail establishments. Int J Food Microbiol, 123, 121–129.
32. 31. Doğan-Halkman HB, Çakır İ, Keven F, Worobo RW, Halkman AK. 2003. Relationship among fecalcoliforms and Escherichia coli in various foods. Eur Food Res Technol, 216, 331–334.
33. 32. Cruz AG, Cenci SA, Maia MCA. 2008. Microbiological hazards involved in fresh-cut lettuce processing. J Sci Food Agr, 88, 1455–1463.
34. 33. Meldrum RJ, Little CI, Sagoo S, Mithani V, McLauchlin J, Pinna E. 2009. Assesment of the microbiological safety of salad vegetables and sauces from kebab takeaway restaurants in the United Kingdom. Food Microbiol, 26, 573–577.
35. 34. Sengun IY, Karapinar M. 2005. Effectiveness of household natural sanitizers in the elimination of Salmonella typhimurium on rocket (Eruca sativa Miller) and spring onion (Allium cepa L.). Int J Food Microbiol, 98, 319-315.
36. 35. Singh N, Singh RK, Bhunia AK, Stroshine RL. 2002. Efficacy of Chlorine dioxide, Ozone, and Thyme essential oil or a sequential washing in killing Escherichia coli O157:H7 on lettuce and baby carrots. LWT-Food Sci Technol, 35, 720–729.