Mihalıç peynirlerinin olgunlaşması sırasında gıda zehirlenmesine neden olan Bacillus Cereus'un yaşam süresi üzerinde araştırmalar
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Date
2000
Authors
Temelli, Seran
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Publisher
Uludağ Üniversitesi
Abstract
Yöresel peynirlerimizden olan ve çiğ sütten üretilen Mihalıç peynirlerinde, son yıllarda süt ve süt ürünlerinden kaynaklanan gıda zehirlenmelerinde sıklıkla söz edilen Bacillus cere us' un varlığı ve yaşam süresi araştırıldı. Bu amaçla, peynir yapılacak çiğ süte 105 kob/ml düzeyinde B.cereus DSM 4384 susu ilave edildi. Üretilen peynirler 3 farklı tuz konsantrasyonundaki salamuralarda (LGrup; % 12 - % 14 - % 16'lık, 2.Grup; % 14 - % 16 - % 18'lik ve 3. Grup; % 16 - % 18 - % 20'lik) 3 aylık olgunlaşmaya bırakıldı. Her bir grup için yapılan peynirler 3'er kez tekrarlandı. Üretim aşamasında 0., 2., 4. ve ö.saatlerde, olgunlaşma dönemi boyunca da 1., 3., 5., 8., 15., 20., 30., 45., 60. ve 90. günlerde örnekler alınarak mikrobiyolojik olarak, B.cereus, Aerob mezofil genel canlı, Koliform bakteriler, Stafilokok-Mikrokoklar, Laktobasiller, Maya ve küf yönünden; kimyasal olarak da kurumadde, yağ, tuz ve asitlik yönünden analizleri yapıldı. 1.ve 2.Grupta ortalama B.cereus sayısı, 2.saatte sırası ile 5.8x1 05 kob/ml ve 2.5x1 05 kob/ml seviyelerinde iken 90.gün saptama sınırının altında (<1.0x102kob/g) bulundu. 3.Grupta ise çiğ sütte ortalama 2.7x1 06 kob/ml düzeyinde bulunan B.cereus, olgunlaşmanın 60.ve 90.günlerinde saptama sınırının altında tespit edildi.Ortalama Aerob mezofil genel canlı sayısı, olgunlaşmanın sonunda 1. Grupta 1.5x1 06 kob/g, 2. Grupta 2.7x1 06 kob/g ve 3.Grupta 2.6x1 05 kob/g seviyesinde bulundu. Koliform bakterilerin ortalama sayısı, LGrup peynirlerde olgunlaşmanın sonunda 3.2x1 03 kob/g, 2.Grupta 9.3x1u2 kob/g ve 3. Grupta da 4.0x1 02 kob/g düzeyinde tespit edildi. 1. Grupta ortalama Stafilokok-Mikrokok sayıları, 90.günde 8.8x1u2 kob/g, 2.Grupta 3.0x1 03 kob/g, 3. Grupta ise 5.0x1 03 kob/g düzeyinde bulundu. Laktobasillerin ortalama sayısı, 1. Grupta 90. gün 1.4x1 05 kob/g, 2. Grupta 4.0x1 05 kob/g ve 3.Grupta 7.6x1 04 kob/g seviyesinde bulundu. Ortalama Maya ve küf sayıları, LGrup peynirlerde olgunlaşmanın sonunda 1.0x103 kob/g, 2.Grupta 1.1x102 kob/g ve 3. Grupta da 1.3x1 03 kob/g düzeyinde tespit edildi. Kurumadde değerleri ortalama, 1. Grupta olgunlaşma sonunda % 59.79, 2. Grupta % 60.26, 3. Grupta da % 61.66 olarak tespit edildi. Ortalama kurumaddede yağ değerleri, 1. Grupta olgunlaşma sonunda % 42.95, 2.Grupta % 45.72, 3.Grupta ise % 48.13 oranlarında tespit edildi. Kurumaddede tuz değerleri ortalama olarak, LGrup peynirlerde 90.gün % 13.77, 2.Grupta % 15.04, 3.Grupta ise % 20.11 oranlarında bulundu. Ortalama asitlik değerleri, LGrupta 90.gün % 1.38 L.A., 2.Grupta 90.gün % 1.32 L.A., 3.Grupta ise % 1.23 LA oranlarında tespit edildi. Çalışmamızın sonucunda, çiğ sütlerden üretilen Mihalıç peynirlerinde B.cereus' un, salamuradan peynirlere tuz geçişine ve asitlik artışına bağlı olarak 60- 90. günlerde yıkımlandığı ve saptama sınırının altında olduğu tespit edildi. Ayrıca Mihalıç peynirlerinin başlangıçtaki yüksek mikroorganizma yükünün aynı etkenlere bağlı olarak 30. - 45. günlerden sonra tehlike sınırının altına düşmeye başladığı ortaya konuldu.
The presence and the survival of Bacillus cereus, which is recently and frequently reported as the causative agent in food-poisoning from milk and dairy products, was studied in Mihalic cheese, a local cheese, produced from raw milk. For this purpose, 10s cfu/ml B.cereus OSM 4384 strain was added into the milk to be used in making cheese. Produced cheese were stored for ripening for 3 months in pickling solutions with 3 different salt concentrations (Group 1; 12 %, 14 %, 16 %, Group 2; 14 %, 16 %, 18 %, Group 3; 16 %, 18 %, 20 %). Cheese production was repeated three times for each group. During the production period, at 0, 2, 4, and 6 hours, and during the ripening period, in days 1, 3, 5, 8, 15, 20, 30, 45, 60, 90, specimens were collected and examined microbiologically for B.cereus, Aerob mesophilic general viable, Coliform, Staphylococcus-Micrococcus, Lactobacilli, Yeast and mold, and analyzed chemically for dry matter, total fat, salt and acidity. In Groups 1 and 2, mean B.cereus counts were 5.8x1 0s cfu/ml and 2.5x1 05 cfu/ml in hour 2, respectively. The counts were found to be lower than the detection limits in day 90 for both of these groups. In Group 3, mean B.cereus count, which was 2.7x1 06 cfu/ml in hour 2, was determined to be under the detection limits during the 60th and 90th days of ripening. Aerob mesophilic general viable counts were found as 1.5x1 06 cfu/g in Group 1, 2.7x1 0s cfu/g in Group 2, and 2.6x1 05 cfu/g in Group 3. Mean Coliform counts in the end of ripening were determined as 3.2x1 03 cfu/g in Group 1, 9.3x1 02 cfu/g in Group 2, and 4.0x1 02 cfu/g in Group 3. Mean Staphylococcus-Micrococcus counts in day 90 3were found as 8.8x1 02 cfu/g in Group 1, 3.0x1 03 cfu/g in Group 2, and 5.0x1 03 cfu/g in Group 3. In day 90, Lactobacilli mean counts were found in the following levels: 1.4x105 cfu/g in Group 1, 4.0x1 05 cfu/g in Group 2, and 7.6x1 04 cfu/g in Group 3. Mean Yeast and mold counts in the end of the ripening period were determined as 1.0x1 03 cfu/g in Group 1, 1.1x102 cfu/g in Group 2, and 1.3x1 03 cfu/g in Group 3. Mean dry matter values were determined as 59.79 % in Group 1, 60.26 % in Group 2, and 61.66 % in Group 3 in the end of the ripening period. Mean fat in dry matter in the end of the ripening period were determined as 42.95 % in Group 1, 45.72 % in Group 2, and 48.13 % in Group 3. Mean salt values in dry matter were found as 13.77 % in Group 1, 15.04 % in Group 2, and 20.11 % in Group 3 in day 90. Mean acidity values in day 90 were determined as 1.38 % in Group 1, 1.32 % in Group 2, and 1.23 % in Group 3 in the end of the ripening period. As results of our study, in Mihalic cheeses produced from raw milk, B.cereus was destroyed due to the salt absorbtion of cheese from pickle and to the increase in the acidity, and mean B.cereus counts were determined to be under the detection limits in days 60 - 90. Also it was determined that the high initial microbial load in Mihalic cheeses started to decrease by days 30 - 45 to the non-hazardous levels due to same factors
The presence and the survival of Bacillus cereus, which is recently and frequently reported as the causative agent in food-poisoning from milk and dairy products, was studied in Mihalic cheese, a local cheese, produced from raw milk. For this purpose, 10s cfu/ml B.cereus OSM 4384 strain was added into the milk to be used in making cheese. Produced cheese were stored for ripening for 3 months in pickling solutions with 3 different salt concentrations (Group 1; 12 %, 14 %, 16 %, Group 2; 14 %, 16 %, 18 %, Group 3; 16 %, 18 %, 20 %). Cheese production was repeated three times for each group. During the production period, at 0, 2, 4, and 6 hours, and during the ripening period, in days 1, 3, 5, 8, 15, 20, 30, 45, 60, 90, specimens were collected and examined microbiologically for B.cereus, Aerob mesophilic general viable, Coliform, Staphylococcus-Micrococcus, Lactobacilli, Yeast and mold, and analyzed chemically for dry matter, total fat, salt and acidity. In Groups 1 and 2, mean B.cereus counts were 5.8x1 0s cfu/ml and 2.5x1 05 cfu/ml in hour 2, respectively. The counts were found to be lower than the detection limits in day 90 for both of these groups. In Group 3, mean B.cereus count, which was 2.7x1 06 cfu/ml in hour 2, was determined to be under the detection limits during the 60th and 90th days of ripening. Aerob mesophilic general viable counts were found as 1.5x1 06 cfu/g in Group 1, 2.7x1 0s cfu/g in Group 2, and 2.6x1 05 cfu/g in Group 3. Mean Coliform counts in the end of ripening were determined as 3.2x1 03 cfu/g in Group 1, 9.3x1 02 cfu/g in Group 2, and 4.0x1 02 cfu/g in Group 3. Mean Staphylococcus-Micrococcus counts in day 90 3were found as 8.8x1 02 cfu/g in Group 1, 3.0x1 03 cfu/g in Group 2, and 5.0x1 03 cfu/g in Group 3. In day 90, Lactobacilli mean counts were found in the following levels: 1.4x105 cfu/g in Group 1, 4.0x1 05 cfu/g in Group 2, and 7.6x1 04 cfu/g in Group 3. Mean Yeast and mold counts in the end of the ripening period were determined as 1.0x1 03 cfu/g in Group 1, 1.1x102 cfu/g in Group 2, and 1.3x1 03 cfu/g in Group 3. Mean dry matter values were determined as 59.79 % in Group 1, 60.26 % in Group 2, and 61.66 % in Group 3 in the end of the ripening period. Mean fat in dry matter in the end of the ripening period were determined as 42.95 % in Group 1, 45.72 % in Group 2, and 48.13 % in Group 3. Mean salt values in dry matter were found as 13.77 % in Group 1, 15.04 % in Group 2, and 20.11 % in Group 3 in day 90. Mean acidity values in day 90 were determined as 1.38 % in Group 1, 1.32 % in Group 2, and 1.23 % in Group 3 in the end of the ripening period. As results of our study, in Mihalic cheeses produced from raw milk, B.cereus was destroyed due to the salt absorbtion of cheese from pickle and to the increase in the acidity, and mean B.cereus counts were determined to be under the detection limits in days 60 - 90. Also it was determined that the high initial microbial load in Mihalic cheeses started to decrease by days 30 - 45 to the non-hazardous levels due to same factors
Description
Keywords
Mihalıç peyniri, Olgunlaşma, Canlılık, Bacillus cereus, Mihalic cheese, Ripening, Survival
Citation
Temelli, S. (2000). Mihalıç peynirlerinin olgunlaşması sırasında gıda zehirlenmesine neden olan Bacillus Cereus'un yaşam süresi üzerinde araştırmalar. Yayınlanmamış doktora tezi. Uludağ Üniversitesi Sağlık Bilimleri Enstitüsü.