Sodium benzoate and potassium sorbates are the two typical preservatives widely used in Vietnam and other countries. The maximum level (ML) of sodium benzoate and potassium sorbate in processed meat products imposed by Ministry of Public Health is 1000 ppm. Although there are warnings about overusing of these preservatives that related to human health, many manufacturers do not follow the regulations. The aim of this study was to survey and consider the amounts and presence of these preservatives in processed meat products by using High-performance liquid chromatography (HPLC) method. 90 samples of brands and no brands including Vietnamese pork rolls, pâtés, hams, sausages, and fermented pork rolls that available at markets in Ho Chi Minh City were analysed for these two preservatives. There was a preference for using sodium benzoate in all samples. Moreover, Vietnamese pork roll samples had the highest percentage of samples with preservatives concentrations exceeding the ML. Among 90 samples, sodium benzoate was detected in 52.2% of samples and 17.8% of them exceeded the ML, while potassium sorbate was found in 24.4% of samples and only 2.2% of them exceeded the regulated amount. 46.4% of Vietnamese pork rolls, 12.5% of pâtés, and 9.1% of fermented pork rolls had sodium benzoate exceeded the ML, whilst ham and sausage samples contained the concentrations inside the safety limits. Furthermore, only one sample of Vietnamese pork rolls and one sample of sausages had potassium sorbate concentrations surpassing the ML with the level of 1,717.57 mg/kg and 1,814.00 mg/kg, respectively. Furthermore, branded samples showed a significantly different result in compared with no branded samples. Of branded samples, exceeding sodium benzoate level ML was detected in 10% of samples and none of the samples found surpassing potassium sorbate limit amount. Nevertheless, 27.5% and 5% of unbranded samples had sodium benzoate and potassium sorbate higher than the authorized amounts, respectively. New strategies should be established to monitor the food safety issues.

Purple nonsulfur bacteria are a group of diverse biotechnological applications, particularly in producing functional food rich in unsaturated fatty acids. In this study, a purple nonsulfur bacterium strain HPB.6 was chosen based on its strong growth, high lipid production and synthesis of unsaturated fatty acid (omega 6, 7, 9). The studying on biological characteristics showed that strain HPB.6 comprises ovoid-rod shaped cells with diameter of 0.8 -1.0 µm, none motile, Gram negative stained. The cells divide by binary fission and contain bacteriochlorophyll a (Bchl a). This bacterium grew well on medium with carbon and nitrogen sources such as acetate, succinate, pyruvate, butyrate, glutamate, arginine, leucine, tyrosine, alanine, methionine, threonine, glutamine, yeast extract and NH 4 Cl. This selected strain grew well on medium with salt concentrations from 1.5 -6.0 % (optimum 3 %), pH from 5.0 to 8.0 (optimum at pH 6.5) and could withstand Na 2 S at 0.4 -5.2 mM. All the data and particularly 16S rRNA analysis received demonstrated that HPB.6 strain belongs to the species Rhodovulum sulfidophilum.