Abstract
A Total of six groups of fresh broiler carcasses randomly collected from different poultry shops at Alexandria province. After examination of an untreated samples, the samples were classified into six groups, each group was represented by their muscle samples which were dipped in acid solutions as follows; the 1st group was dipped in 1% lactic acid solution v/v for five min., the 2nd group was dipped in 2% lactic acid solution v/v for five min., the 3rd group was dipped in 1% acetic acid solution v/v for five min., the 4th group was dipped in 2% acetic acid solution v/v for five min., the 5th group was dipped in 1% mixture of lactic and acetic acids v/v for five min. and the 6th group was dipped in 2% mixture of lactic and acetic acids v/v for five min. Determination of spoilage markers including determination of pH and total volatile nitrogen (TVN) was performed beside determination of aerobic plate count (APC), psychrophilic bacteria count and Enterobacteriaceae count. The inhibitory effect of lactic acid and acetic acid on microbial population has long been used to preserve food from spoilage, while much of the effect can be accounted for pH and temperature of storage. Immersion of the examined samples with 1, 2 % (lactic, acetic acids). chilled for 1, 2, 4, 6, 8, 10 and 12 days resulted in population reductions of aerobic bacteria, psychrophilic and Enterobacteriaceae. Effect of organic acids as lactic acid, acetic acid and mixture of lactic and acetic acids are mainly affecting growth of microorganisms mainly by lowering of pH and increase acidity of media. The acids have effect until 10 days of storage at chilling condition in case of 1% concentration, but its effect reach to 12 days in case of 2% concentration.

Key words: lactic, Acetic, acids, Bacteria, Broilers