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Register a new userStudy of the inhibition effect of yoghurt starter on Staph. aureus bacteria
دراسة الأثر التثبيطي لبكتريا بادئ اليوغورت (اللبن الرائب) في نمو بكتيريا Staph. aureus
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Damascus University ورقة بحثية
Publication date
2010
fields
Food Sciences
and research's language is
العربية
Created by
Shamra Editor
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هدف هذا البحث الذي أجري في مخابر كلية الزراعة بجامعة دمشق قسم علوم الأغذية إلى دراسـة الأثر التثبيطي لنمو و نشاط بكتيريا حمض اللبن المستخدمة كبادئات في صناعة اللبن الرائب المحلي فـي نمو بكتيريا aureus. Staph ، و قد استخدم من أجل ذلـك البـادئ (thermophilus Streptococcus و bulgaricus Lactobacillus) و سلالة نقية من بكتيريا aureus. Staph المنمطة في قـسم علـوم الأغذية بجامعة دمشق، لُقّحت هذه السلالة في الحليب المعد لصناعة اللبن الرائب و حفظ اللبن الناتج فـي درجتي حرارة 37ْ م و حرارة تخزين 4ْ م. لوحظ ثبات في أعداد aureus. Staph خلال المدة الأولى من الاختبار، و من ثم بدأ انخفاض الأعداد تدريجياً تبعاً للزمن، و كان انخفاض أعدادها أكثـر وضـوحاً عنـد استخدام البادئ المزدوج، و من ثم بكتيريا bulgaricus. Lb وحدها كبادئ، و كان الأقل تأثيراً اسـتخدام بكتيريا thermophilus. Str وحدها كبادئ.
This investigation was done in the laboratories of the Faculty of Agriculture – Damascus University in the Department of Food Sciences. The aim of this research use to study the inhibition effect of the growth and activity of Lactic acid bacteria used as starter and on the growth of Staph. aureus bacteria. Pure strains of Staph. aureus and Lactic acid bacteria was used the effect of Lactic acid bacteria (Streptococcus thermophilus and Lactobacillus bulgaricus) on the number of Staph. aureus was studied at 37 ◦C and 4◦C. The Lactic acid bacteria were inoculeted in milk for the manufacturing of yoghurt. The number of Staph. aureus was fixed then was decreased gradually according to time. And the decreasing number of this bacteria was clear when S. thermophilus and Lb. bulgaricus were used as a mixture starter, then when was used as a single starter, Lb. bulgaricus and S. thermophilus.
References used
Abdelnoor, A. M., Batshoun R., and Roumani B. M. (1983). "The bacterial flora of fruits and vegetables in Lebanon and the effect of washing on the bacterial content" Zentralbl. Bakteriol. Mikrobiol. Hyg. 177 :342–349
Alexandre, D. P., Silva M. R. Souza M. R. (2002). “Antimicrobial activity of lactic acid bacteria from artisonal minas cheese against indication microorganisms” Arquivo brasilerio de medicina veterinaria 54: 424 – 428
Ash, M. (1997). "Staphylococcus aureus and Staphylococcal Enterotoxins. In: Foodborne microorganisms of the public health importance, 5 Edition", (Eds) Hocking, A.D., Arnold, G., Jenson, I., Newton, K. and Sutherland, P. AIFST (NSW Branch), Sydney, Australia. 313-332
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This investigation was done in the laboratories of Faculty of Agriculture –
Damascus University Department of Food Sciences. The aim of this research
was to study the inhibition effect of the growth of Lactic acid bacteria used as
starter, on the
growth of S. typhi O9 bacteria. We used for this study a pure
strains of Salmonella typhi O9 and Lactic acid bacteria (Streptococcus
thermophilus and Lactobacillus bulgaricus). The effect of Lactic acid bacteria on
the number of S. typhi O9 was studied in 37 ◦C and 4◦C. The Lactic acid bacteria
were inoculeted in milk for the yoghurt manufacturing. The number of S. typhi
O9 decreased gradually with time. This decrease number of this bacteria was
more clear when both Str. thermophilus and Lb. bulgaricus were used as a
mixted starter, Lb. bulgaricus then when was used a single starter, or when Str.
thermophilus was used a alone. The S.typhi O9 disappear
This research was conducted in the laboratories of Faculty of Agriculture –
Damascus University Department of Food Sciences. The aim of this research
was to study the inhibition effect of the growth and activity of Lactic acid
bacteria as starter
in yoghourt, on the growth of E. coli O157:H7 bacteria. A
pure strains of E. coli O157:H7 and Lactic acid bacteria was used for this study.
The effect of Lactic acid bacteria (Streptococcus thermophilus and
Lactobacillus bulgaricus ) in the number of E. coli O157:H7 was studied in 37 ◦C
and 4◦C. The Lactic acid bacteria was inoculeted in milk which was prepared to
manufacture the yoghurt. The number of E. coli O157:H7 was gradually
decreased with the time. The decline number of this bacteria was clear when S.
thermophilus and Lb. bulgaricus were used as a mixture starter , then when Lb.
bulgaricus was used as a single starter then S. thermophilus was used a single,
In the other hand, the inhibition effect was weaker at 37 C and stronger on 4 C.
This study was conducted in order to prolong the period of validity of
yoghurt by adding 5, 10 and 15 g/1 of carrot juice liter during the storage
period of 35 days at 4±°C and 10±1 °C and determine some of the microbial،
chemical and sensory char
acteristics of yoghurt after 1, 7, 14, 21, 28 and 35
days of storage. The results indicated that the vital force had lasted for 7 days
in control samples and 28 days and 35 for samples containing 5, 10 g or 15 g
carrot juice, respectively when stored at 4±1 °C. No significant differences were
observed when samples stored at 10±1 °C. The results also indicated that the
sensory properties of yoghurt containing 5g of the carrot juice were more
favorably than those containing higher proportions due to the absence of taste
and color of carrot juice in the samples. it was also shown the addition of carrot
juice did not affect the pH levels and sensory property values during storage.
Furthermore، shelf-life did not exceed more than 7 days in control samples
while it lasted up to 35 days in yoghurt samples containing carrot juice.
This research aimed to study the effect of various growth conditions
(temperature, culture age and culture medium) on the fatty acids composition
of cytoplasm membrane of 37 isolates of Staphylococcus aureus using Gas
Chromatography-Mass Spectrome
try (GC-MS). Results revealed that the total
number of fatty acids of Staph. aureus was 33. Eight of them were principle and
included: anti-isotetradecanoic acid (aC15:0), octadecanoic acid (C18:0),
eicosanoic acid (C20:0), isotetradecanoic acid (Ci14:0), isotridecanoic acid
(Ci15:0), hexadecanoic acid (C16:0), antisohexa- decanoic acid (Ca17:0) and
octadecenoic acid (C18:1) with a percentage of 33.96, 18.37, 14.94, 7.32, 6.23,
4.14, 3.03 and 2.89%, respectively. The percentage of each of the other fatty
acids was less than 1%. Increasing the incubation temperature was associated
with reducing the percentages of Ca15:0, Ci15:0, C16:0 and C18:1; and
increasing Ca17:0, Ci14:0, C18:0 and C20:0. The increase in incubation period
caused a decrease in C16:0, C18:0, C18:1 and C20:0; and an increase in Ca15:0
and Ca17:0. Moreover, the variation in culture media caused differences in the
percent of Ca15:0, C18:0 and C20:0; while the other fatty acids showed no
changes.
This study was conducted in order to prolong the period of validity of
yoghurt by adding probiotics consisted of Lactobacillus acidophilus LA-5 and
Bifidobacterium animalis subsp lactis (Bb12) to milk allocated to yoghurt
industry and studied the
microbial, chemical and sensory characteristics of
yoghurt during storage periods for 0, 7،,14, 21, 28, 35 and 42 days at 4 ± 1 °C
and 10 ± 1 °C. The results of microbial characteristics showed that the vital
force of the first starter lasted for 7 days in the control samples while lasted for
35 days for the sample containing Lactobacillus acidophilus LA-5 or
Bifidobacterium animalis subsp lactis (Bb12) when stored at 4 ± 1°C. Adding
probiotics did not affect the taste, smell and pH of the yoghurt without change
in the property values during storage periods. It was also found that the shelf –
life of control samples can be prolonged and consumed safely up to 7 days of
storage while it was prolonged for 35 days in yoghurt samples containing
probiotics.
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