P3-125 Enumeration and Identification of Spoilage Lactic Acid Bacteria in Chilled Food Products Using 3M™ Petrifilm™ Lactic Acid Bacteria Count Plate

Wednesday, July 12, 2017
Exhibit Hall (Tampa Convention Center)
Siti Aisha Abd Aziz , ALS Technichem , Shah Alam , Malaysia
Su Ann Lee , ALS Technichem , Shah Alam , Malaysia
Teen Teen Chin , ALS Technichem , Shah Alam , Malaysia
Hui Key Lee , University of Malaya , Kuala Lumpur , Malaysia
Chandraprasad S Rajangan , 3M Malaysia , Petaling Jaya , Malaysia
Lay Ching Chai , University of Malaya , Kuala Lumpur , Malaysia
Introduction: Lactic acid bacteria (LAB) are the major bacteria groups associated to spoilage of food products, particularly in reduced oxygen packaging (ROP). Understanding the diversity of LAB associated to spoilage in ROP product and non-ROP product is essential in improving the product quality and shelf life that will lead to a reduction in food waste.

Purpose:  Assess the impact of storage temperature on the abundance and diversity of LAB in selected ROP food products.

Methods:  A total of 200 ROP chilled food products were purchased from the local retail. A portion of the samples were stored at 4oC or 25-27oC for 20h before the microbiological assessment was performed. Total aerobic bacteria (TPC) and LAB in food products were enumerated using 3MTM PetrifilmTM Aerobic Count Plate and 3MTM PetrifilmTM Lactic Acid Bacteria Count Plate, respectively. About 5-10 LAB colonies were isolated from each sample for bacterial identification.

Results: LAB were detected in 74% of the total samples, that ranged from 1.00-7.48 log10CFU/g, with significantly higher counts in ROP products including chicken sausage, chicken rolls and mushrooms (p<0.01) compared to produce, sauces and starchy foods. The LAB counts in food products stored at room temperature were significantly higher compared to before and after storage at 4°C (p<0.05). ROP products stored at 4°C for 20h did not significantly increase the total bacteria count (p>0.05), but the LAB had a significant increase (p<0.01) with about 1.02 log10CFU/g increment for LAB.

Significance: LAB were present in the majority of the chilled food products included in this study, particularly in ROP products. Refrigeration and ROP arrest only the growth of aerobic bacteria, but not LAB that may cause spoilage. Quantification and control of LAB are essential to optimize shelf life of food ROP products.