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ABSTRACT


Pesticides can pose risks and technological problems of dairy products if used improperly or frequently. The present work aims to investigate the effect of two fungicides Anadol and Tasolen, herbicides Round up and Saturn and insecticides Lannate and Reldan commonly used in Egypt on certain lactic acid bacteria Streptococcus salivarius subsp. thermophilus H, Lactobacillus acidophilus Type 145, Lactobacillus casei subsp. casei, Lactobacillus delbrueckii subsp. bulgaricus and Bifidobacterium spp. 420 and their impact on acid, acetaldehyde and diacetyl production by yogurt and ABT cultures. The concentrations of pesticides 1-10 ppm were added to selective media immediately before inoculation with tested bacteria, incubated then colonies of bacteria were counted. The Pesticides were added to inoculated skim milk with tested bacteria then incubated, acidity development was determined. Yoghurt and ABT yoghurt were made in the presence of previous pesticides concentrations, acid, acetaldehyde and diacetyl production were estimated. The two insecticides caused the greatest harmful effect on acid production of most strains and acid, acetaldehyde and diacetyl production in yoghurt and ABT yoghurt followed by herbicides then fungicides, the effect of 2 ppm concentration on acetaldehyde, diacetyl and acid production was negligible reverse 8 and 10 ppm concentrations. Nevertheless, L. acidophilus was more resistant to Anadol. While, Bifidobacterium spp. 420 was the most sensitive for Anadol and Tasolen. However, L. bulgaricus was the most resistant to Tasolen. St. theromophilus was the most sensitive for herbicides unlike L. acidophilus. L. bulgaricus surpassed other bacteria in tolerance insecticides, on the contrary, Bifidobacteria spp. exhibited excessive sensitive toward insecticides.

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