Journal of Food Quality and Hazards Control
Volume:2 Issue: 4, Dec 2015

Extracellular polymeric substances are defined as high molecular weight compounds secreted by the microorganisms in the surrounding area. Since these extracellular substances are mainly polysaccharide, they are named exopolysaccharide. Microbial exopolysaccharides as high molecular weight polymers, composed of sugar residue have growing interest as a new class of microbial products which can be used in food, pharmaceutical, and biomedical industries. Microbial derived exopolysaccharides are considered as either good substitute of other synthetic or natural polymers or novel biopolymers which are used in food for thickening, suspending and gelling function. Although, microbial derived compounds have a versatile reputation and the numbers of published articles in this area are increasing, only three exopolysaccharides xanthan, gellan and dextran have been survived the industrial competition. Regarding the importance of these three ones, they have been discussed in detail in this paper. In this review article, the function and application of microbial exopolysaccharides are discussed regarding their physical properties and chemical structure.

Sarcocystosis in South American camelids (SAC) is an important parasitic disease which results in economical loss due to carcass condemnation. Meat products from camelids are significant source of animal protein in several American countries. Sarcocystis spp. producing macroscopical cysts in these animals have been nominated as S. aucheniae, S. tilopodi, and S. guanicoecanis. The aim of the present study was to characterize morphologically and molecularly Sarcocystis spp. producing macroscopical cysts in guanacos (Lama guanicoe). Samples of macroscopical cysts were dissected from guanaco muscles slaughtered in Santa Cruz province, Argentina. The samples were processed by transmission electron microscopy, polymerase chain reaction (PCR), cloning and sequencing studies. Cyst wall villar protrusions were irregular with a “tree” or “cauliflower-like” shape which measured 3-4.5 µm height by 2.5-3.5 µm width. A consensus 18S rRNA full gene sequence of 1875 bp was obtained and showed the highest identity (≥ 99 %) with sequences of S. aucheniae reported in GenBank. The ultra structure of the cyst wall from macroscopical cysts and 18S rRNA gene obtained from guanacos were identical and consistent with the descriptions of S. aucheniae. This study confirms that guanacos are infected by the same Sarcocystis spp. affecting other SAC, named S. aucheniae, and reinforce the suggestion that nomination of new species should contain morphological and molecular data to reach validity. In future, this data could be useful to obtain proper identifications in post-mortem inspection and helpful to improve meat safety.

Unlike industrially production, Iranian traditional doogh are not pasteurized after production. Hence, possible contamination with different pathogenic bacteria may occur during production or post-production of traditional doogh. The aim of the present study was to monitor the behavior of Escherichia coli O157:H7 and Listeria monocytogenes in traditional Iranian doogh at different temperatures and time periods. Low acid and high acid doogh samples were inoculated with approximately 4 and 6 log cfu/ml of each pathogen separately and incubated at 4 ºC and 25 ºC. At different time interval, samples were taken to enumerate E. coli O157:H7 and L. monocytogenes and determine titratable acidity. Results were analyzed by ANOVA test using SPSS software (v. 16.0). Although the survival ability of E. coli O157:H7 in doogh samples was slightly higher than L. monocytogenes, both of them were detected in low acid doogh sample after 10-14 days at 4 ºC. However, they were not detected in low acid doogh samples for more than 2 days at 25 ºC. In contrast, in high acid doogh samples, the viability of E. coli O157:H7 and L. monocytogenes declined more quickly to undetectable level, both at 4 ºC and 25 ºC indicating less viability of these bacteria in high acid doogh samples compared to those of low acid ones (p<0.05). Traditional Iranian doogh should be considered as a potential vehicle of transmission of E. coli O157:H7 and L. monocytogenes, especially in low acid doogh samples when stored under refrigeration.

In recent years, there has been an increasing interest in using food additives from natural sources to improve taste and also extend shelf life of semi-preserved food. The aim of this paper was to examine chemical and microbiological changes promoted by a traditional marinating process in rainbow trout fillets during frozen storage. Fish fillets were immersed in traditional marinades and stored at -18 °C for 56 days. Some chemical and microbial characteristics like total volatile basic nitrogen (TVN), thiobarbituric acid (TBA), water holding capacity (WHC), pH, mesophilic, and psychrophilic bacterial count were performed with 7 days interval. The results were analyzed by repeated measure ANOVA test using SPSS 16.0 software. Data showed that although the value of TVN, TBA and, WHC in marinated samples were higher than control ones, but the differences were not significant (p>0.05). The numbers of bacteria in marinated samples were lower than control groups and for psychrophilic bacteria was significant (p<0.05). The most obvious finding to emerge from this study is that rainbow trout flesh could be marinated and stored at -18 ˚C for at least 56 days with no major unfavorable changes.

Considering high importance of heavy metals residue from view point of food safety, this study was conducted to determine the contents of chromium (Cr), lead (Pb) and cadmium (Cd) in different tissues (liver, heart and muscle) of Marketed Chickens in Mashhad, Iran. Chicken tissues were collected from four popular brands distributed in different markets in Mashhad, followed by preparing through acidic digestion and analyzing using graphite furnace atomic absorption spectrometry. All statistical significant differences were defined at p<0.05 using SPSS v. 16.0. Mean concentration (±standard deviation) of heavy metals in the liver, heart and muscle of chicken samples were 3.87 ± 3.94, 3.77 ± 2.77 and 2.27 ± 1.07 mg/kg (for Cr), 3.79 ± 3.64, 2.65 ± 1.88 and 1.65 ± 1.09 mg/kg (for Pb) as well as 0.37 ± 0.09, 0.32 ± 0.1 and 0.28 ± 0.07 mg/kg (for Cd), respectively, indicting higher heavy metals levels in liver and heart samples compared to those of muscle ones (p<0.05). The contents of some heavy metals in chicken samples are warning that highlights its public health risk in this region of Iran. Therefore, more effective monitoring procedures and surveillance programs should be applied by the authorities of regional veterinary organization.

The criteria for the quality control of Iranian fresh produce are the total microbial count, Enterococcal count and the detection of Escherichia coli. The aim of this study was to assess microbial contamination of fresh vegetable and salad samples consumed in Tehran, Iran. From May to October 2013, freshly vegetable (n=100) and salads (n=100) samples were randomly collected in three area of Tehran including Islamshahr (n=35), South of Tehran (n=30) and Shahr-e-Rey (n=35). The samples were tested microbiologically according to institute of standards and industrial research of Iran (ISIRI) for determination of total microbial, Enterococcal and E. coli count. The results were analyzed by SPSS software. Overall, 71% of salad and 82% of vegetable samples had contamination rate more than acceptable limits in the case of at least one of the three microbial parameters. All of spinaches, wheat sprouts, mung bean sprouts, mixed leafy vegetables, Kuku vegetables, and green peppers were exceeded acceptable limits at least in case of one parameter. From 71 ineligible salad samples, 24 samples (68.6%) were for Islamshahr, 26 samples (74.3%) for South of Tehran and 21 ones (70%) for Shar-e-Rey, with no significant difference (p>0.05). This study showed poor microbiological quality of salad and fresh vegetables used in Tehran. Measures to reduce the contamination might be advised such as a proper handling and washing before consumption of these products as well as public education and awareness.