ที่มา:วิทยาสารเกษตรศาสตร์ สาขา วิทยาศาสตร์

หัวเรื่อง:ไม่มีชื่อไทย (ชื่ออังกฤษ : Survival of Shiga Toxin-producing Escherichia coli (O157:H7 and Non-O157:H7) and Effectiveness of Thermal Inactivation by Microwaves in Nham (Thai Fermented Sausage))

ผู้เขียน:ดร.วลัยรัตน์ จันทรปานนท์, ผู้ช่วยศาสตราจารย์, ดร.สุนีย์ นิธิสินประเสริฐ, รองศาสตราจารย์, Joseph F. Frank

สื่อสิ่งพิมพ์:pdf

Abstract

A study was conducted to determine if the fermentation conditions of Nham (Thai fermented sausage) were effective against Escherichia coli O157:H7 and three non-O157:H7 Shiga toxin-producing E. coli, O8 (stx2+, eaeA-), O111 (stx1+, eaeA+) and untypable O serogroup (stx1+, eaeA-) strain, compared with non pathogenic E. coli, E780 as a negative control. Nham was produced using starter cultures of V3 (Pediococcus acidilactici and Staphylococcus xylosus). The pH of Nham during the fi rst 3 d of Nham fermentation was reduced from 6.39 to 4.55. Each of the fi ve strains of E. coli were separately inoculated to unfermented Nham giving initial populations of approximately 2 ? 106 colony forming units (CFU).g-1 and fermented at 35 ?C for 3 d and stored at 4 ?C for up to 20 d after that. All strains except O157:H7 were increased by 1 log CFU.g-1 for the fi rst day of fermentation and decreased by 1 to 2 log CFU.g-1 after Nham fermentation for 3 d. After storing inoculated Nham at 4 ?C, the three strains of non-O157:H7 slowly decreased by only 0.5–1 log CFU.g-1 until 20 d of storage at 4 ?C. The effectiveness of thermal activation was determined using a capillary tube method. The decimal reduction time (D) values at 58 ?C in acidifi ed tryptic soy broth (TSB, pH 4.6) of all strains of nonacid-adapted E. coli (TSB) were higher than for the acid-adapted E. coli (TSB pH 5.8). Nonacid-adapted and acidadapted E. coli O111 showed the highest D values (3.31 and 1.23 min, respectively) at 58 ?C while nonacid-adapted and acid-adapted E. coli O157:H7 showed the lowest D values (1.96 and 0.37 min, respectively). The results showed that heating by 900 W microwaves at initial temperatures of 28 ?C for 60 s could not destroy any Shiga toxin-producing E. coli (approximately 1 ? 105 CFU.g-1) in Nham. E. coli O157:H7 could be destroyed after heating with microwaves for up to 90 s but not all E. coli O111 were. Microwaving Nham might not be a safe way of cooking Nham as some E. coli can survive.

Article Info

Agriculture and Natural Resources -- formerly Kasetsart Journal (Natural Science), Volume 046, Issue 6, Nov 12 - Dec 12, Page 966 - 977 |  PDF |  Page

ที่มา:วิทยาสารเกษตรศาสตร์ สาขา วิทยาศาสตร์

หัวเรื่อง:การปนเปื้อนของเชื้อจุลินทรีย์ที่ทำให้เกิดโรคในวัตถุดิบสำหรับผลิตน้ำพริกสำเร็จรูป และการศึกษาระยะเวลาในการอบเพื่อลดปริมาณ

ผู้เขียน:Siriporn Stonsaovapsk, นายปราโมทย์ ธรรมรัตน์, นางสาวกาญจนิจ วาจานะวินิจ

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Abstract

Initial microbial loads of raw materials such as onion, garlic, dried shrimp, dried chilli and shrimp paste (kapi) that used in producing ready-made chilli paste were analysed. The results indicated that most of them contained high numbers of microorganisms. The total viable counts ranged from log10 CFU/g 4.279 – 7.778. The heaviest contamination was dried chilli. Escherichia coli were found between <3-4.6 x 102 MPN/g. None of them was found to contain Salmonella spp. Staphylococcus aureus and Bacillus cereus were found ranging from log10 CFU/g 0 – 3.301 and 0 – 2.000, respectively. Clostridium perfringens was in the range of log10 CFU/g 1.000-4.623 and found in all kinds of raw materials, with high count in dried chilli. After heat treatment at 80?C for 1 hr., the microorganism count in all raw materials were lower but still present, especially C. perfringens. The survival of C. perfringens in dried chilli after holding at 80?C for several hours were specifically investigated. The results revealed that by using the temperature at 80?C for 8 hr., C. perfringens were completely destroyed.

Article Info

Agriculture and Natural Resources -- formerly Kasetsart Journal (Natural Science), Volume 030, Issue 2, Apr 96 - Jun 96, Page 193 - 199 |  PDF |  Page