MPN-duplex PCR detection for salmonella spp. contamination and survival in coconut milk / Nurul Ain Hasani

Salmonella spp. was the most common xause to human Salmonellosis worldwide in the
recent years. Up to October 2018, a total of 83 cases of Salmonella strain outbreak in
Malaysia had been identified. The epidemiologic investigation done before had showed
a significant association between consumption of local food containing coconut milk
and gastrointestinal symptoms in Malaysia. The purpose of this study was to investigate
the presence and susceptibility of Salmonella spp. and Salmonella Typhimurium in
fresh coconut milk at retail level in Negeri Sembilan, Malaysia. A simulation of
decontamination was also conducted to provide the best handling practices while storing
a fresh coconut milk. A total of 120 samples, were randomly purchased from
hypermarket and wet market all around Kuala Pilah, Seremban and Senawang areas at
over one year period (March 2014 until October 2015). The range of the detection of
Salmonella spp. in the sample were ranged from 3.0 x 104 to 2.4 x 107 MPN/ml.
However, the highest microbial loads was found to be at the hypermarket and wet
market in Kuala Pilah with 2.4 x 107 MPN/ml, respectively. A combination technique
of most probable number and duplex polymerase chain reaction (MPN-PCR) method
was used then to quantify on the prevalence and number of total Salmonella spp. in the
fresh coconut milk in Negeri Sembilan, Malaysia. The prevalence of Salmonella spp.
was 74.2% followed by Salmonella Typhimurium with 29.2% from all the three
sampling areas respectively. Here, the highest detection of 85% was for Salmonella spp.
from Seremban and Senawang wet market samples. A slightly low detection of 50%
was detected of the Salmonella Typhimurium from Seremban hypermarket and wet
market samples. Meanwhile, the lowest presence of 15% were found from the
Senawang hypermarket and wet market with 15%. A simulation study was conducted
to overcome the final problem of situation found Salmonella spp. in the fresh coconut
milk. The three treatment were conducted in this simulation. It was found in domestic
kitchen as much as to give a realistic quantitative load on how to reduced that Treatment
3, by adding 2 gram of NaCl2 and boiled up to 60°C for 10 minutes able to reduce the
number of Salmonella spp culture after treatment to 3.0 x 104 CFU/ml. In conclusion,
we found out that fresh coconut milk was easily been contaminated and thus pose a risk
for consumers. Further studies on a bigger scale are recommended to understand the
risks when handling and consuming a contaminated fresh coconut milk.