Efficacy of household washing pre-treatments and cooking methods for reduction of Listeria monocytogenes in artificially contaminated chicken offal

Chee Hao Kuan,Chia Wanq Tan,Tze Young Thung,Nor Ainy Mahyudin,Son Radu,Siok Koon Yeo,John Yew Huat Tang,Chia Yeung New,Eng-Tong Phuah,Nishibuchi Mitsuaki,Lee Sin Chang,Chee Sian Kuan

doi:10.26656/fr.2017.4(1).268

Abstract

Consumption of chicken offal is common and famous among Malaysians as it is often served as one of the side dishes with rice. Chicken offal can be a potential source of Listeria monocytogenes because slaughtered animals are recognized as a reservoir for foodborne pathogens. L. monocytogenes is a dangerous foodborne pathogen which can cause severe foodborne listeriosis with high fatality rate. This study aimed to determine the efficacy of different washing pre-treatment and cooking methods to reduce L. monocytogenes in artificially contaminated chicken offal. All the washing pre-treatments (dip treatment in different water sources and wash treatment with different water flow rates) showed significant reduction of the pathogen (p<0.05) when the inoculated samples were treated from 2 mins onwards. Washing the inoculated samples under the water flow rate of 2 L/min was the most effective way to reduce the number of L. monocytogenes (approximately 1.97 log reduction after washing for 10 mins). For heat treatment study, deep-frying was the most effective cooking method followed by boiling and pan-frying to reduce L. monocytogenes where all L. monocytogenes cells (7.91 log10 CFU/g) were killed within 45 s under deep-frying treatment. Overall, the study indicated that washing under running tap water (2 L/min) and deep-frying was effective in reducing and controlling the microbial populations during food preparation. The findings from this study can serve as a safe preparation step and cooking guideline. It is necessary to implement safe steps in food handling practices among food handlers to minimize the risk of foodborne infection.

Highlights

Chicken offal is commonly referring to the chicken gizzard, chicken heart, and chicken liver which is a cheap source of protein
The present study aimed to investigate the efficacy of different washing pre-treatments and cooking methods to reduce L. monocytogenes on chicken offal
The results showed no significant difference (p>0.05) in the efficacy on the reduction of L. monocytogenes between sample dipped in sterile distilled water and sample dipped in tap water

Summary

Introduction

Chicken offal is commonly referring to the chicken gizzard, chicken heart, and chicken liver which is a cheap source of protein. In Malaysia, consumption of poultry offal is very common, and it is usually consumed as side dishes with rice. As compared to fruits and vegetables, the slaughtered animal has a higher tendency as the source of foodborne pathogens (Mead, 2007; Heredia and García, 2018). This is mainly due to the release of blood and meat blood-like liquid during the slaughtering process, which served as nutrients for microorganisms to grow (Gudbjörnsdóttir et al, 2004). The Ministry of Health Malaysia (MOH) enforced health certificate requirement for importation of edible poultry offal from all countries in order to protect the consumer against contaminated food (MOH, 2005). There is a lack of information regarding the safe handling procedure, pre-treatment, and cooking of the edible offal to ensure it is safe for consumption

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