الفهرس 
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Abstract
This study aimed to investigate 13 types of PAHs and VNAs in some processed meat products (cooked salami, smoked salami, fried frankfurter, fried hot dog and fried sausage) in Assiut City and compared the obtained levels with international standards.
The maximum acceptable concentration of 2 μg kg for BaP and 12 μg kg for PAH4 according to Commission Regulation (EU) (2011) was exceeded in 88% and 58% of samples, respectively. Furthermore, the fried frankfurter had highest total PAHs (55.07 ±5.54 μg kg) and mean of PAH4 was 34.94 ±7.47 μg kg while BaP recorded 15.81±6.90 μg kg. Concerning the lowest level of total PAHs from all samples was in smoked salami (9.29 ± 0.55 μg kg), BaP and PAH4 levels were (1.74 ± 0.98 μg kg) and (4.40 ± 0.55 μg kg), respectively. Among remaining meat products analyzed; cooked salami, the concentration of PAHs was 25.05±2.57 μg kg, BaP (8.89 ± 5.86 μg kg) and PAH4 (15.94± 3.46 μg kg) while fried sausage levels of PAHs recorded 44.94± 4.46 μg kg, BaP (13.23 ± 6.83 μg kg) and PAH4 was 28.51± 5.81 μg kg. Moreover, the mean concentrations of PAHs in fried hot dog was 32.40 ± 3.42 μg kg, also, BaP was 10.82± 5.60 μg kg and PAH4 recorded 19.45± 4.80 μg kg. In addition, and significant correlation between the meat products with the concentration of PAHs (p-value < 0.05) was noted.
Regarding VNAs, the total concentration of the seven nitrosamines in the studied meat products was107. 45 ± 10.23μg kg. The highest level was detected in fried frankfurter (35.11± 9.61 μg/kg) followed by fried sausage (27.67 ±8.37 μg/kg) samples. As for cooked salami, smoked salami and fried hot dog; scored 11.90 ± 2.45, 11.42±1.41 and 21.26 ±4.81 μg/kg, respectively. The obtained results in the presented study revealed that nitrosamine in meat products samples exceeded the limit set by the USDA (2011) of 10 μg/kg.
Additionally, for minimizing the exposure to nitrite to reduce the level of potentially carcinogenic nitrosamines, the present experimental study was designed. Alternative preservation techniques with naturally derived ingredients were investigated. The experimental trial was pointed toward the ability to control the outgrowth of C. perfringens, measuring of pH and over acceptability in designed fresh oriental sausage sample using natural preservatives included nisin and OEO singly and in combinations. Also, promising way to promote antimicrobial safety without changing the sensory characters of food products, enhance stability and controlled release was used. The antimicrobials nisin and OEO loaded nanoparticles were prepared by alginate ionic gelation and further complexation with chitosan applied in the prepared fresh oriental sausage sample.
This study focused on application alginate-chitosan nanocarrier for the encapsulation nisin, as well as OEO. In nisin loaded alginate-chitosan nanoparticles, HRTEM analysis revealed that the size was found to be 46.40 ± 4.08 nm. Furthermore, nanoparticles had an encapsulation efficiency of 98.91%, loading capacity of 75.53%, zeta potential of -65.68 mV. Moreover, the release was nearly 50% for 48 h from the initiation. These results indicated a slow and controlled release of nisin from nanoparticle.
As for OEO loaded alginate-chitosan nanoparticles, HRTEM revealed that the size was 104.73 ± 26.19 nm. Encapsulation efficiency of the nanoparticles was 97.26 and the loading capacity recorded 61.75. Regarding zeta potential was found to be -45.80 mV. The release was achieved 28 % after 48 h which indicating slow and controlled release of OEO from nanoparticle.
In the current study in vitro antibacterial activity of nisin against C. perfringens was o.6 mg/mL and nisin loaded nanoparticles was 0.04 mg/mL as MIC. Concerning OEO antibacterial activity against C. perfringens MIC recorded 3 mg/mL and OEO loaded nanoparticles was 0.08 mg/mL. Also, the result of MIC to the combination of nisin and OEO was 0.4 mg/mL
The results of the sensory evaluation obtained as follow; control samples remained acceptable until 6th day. The treated samples with MIC1(0.6mg/mL) cocentration of free nisin were desirable and accepted until 9th day while samples with MIC2 were desirable untill 12th day.
With regard to free OEO, the overall acceptability of samples treated with MIC1and MIC2 concentrations were affected by the strong odor of OEO and showed significant differences (P< 0.05) compared with control samples, as for signs of spoilage didn’t show until 9th day for MIC1(3mg/mL) treated samples and samples treated with MIC2 (6mg/mL) until 12th day.
Concerning sensory results of the combination of nisin with OEO the samples (MIC1and MIC2) remained accepted until 9th day of storage at 4 °C but the odor of OEO was clear especially in the first days of storage.
Moreover, it found that samples treated with encapsulated nisin both MIC1 and MIC2 were organoleptically accepted until 15th day and 18th day, respectively.
In case of encapsulated OEO both MIC1 and MIC2 scored the same results that remained accepted for 15 days and the masking to the strong odor of OEO was evident. Generally, the highest scores were observed in samples treated with loaded nanoparticles.
The pH measurements showed differences between the treatments and the control in all days of storage. For control sample, pH values were between 6–5.5. The pH values decreased during the storage days for all groups, but within the normal range of meat products.
With respect to the antibacterial activity of different preservatives in the present study; it was revealed that during storage at 4 °C, the highest populations of the pathogen were found in the control samples. Free nisin concentration MIC1(0.6 mg/mL) recorded the highest reduction percentage (79.5%) on 6th day while free nisin MIC2 (1.2 mg/mL) resulted the highest reduction rate (95%) on 12th. Regarding free OEO, on 6th day the both MIC1(3mg/mL) and MIC2(6mg/mL) cocentrations had the highest reduction rates of 80% and 89%, respectively. The combination of nisin and OEO MIC2 (0.8 mg/mL) was the best formula on day zero which could inhibit C. perfringens growth with reduction percentage 92.45% but during storage its ability to reduce the bacterial count decreased and the reduction percentage reached 65% on 9th day.
Based on the findings presented, there was significant reduction in bacterial counts by both nisin and OEO loaded nanoparticles against C. perfringens. Reductions remained until 15th day in case of encapsulated OEO by both MIC1 and MIC2 concentration with reduction percentages 95% and 97%, respectively. Also, the samples treated with encapsulated nisin MIC1 was able to control growth of C. perfringens until 15th day with reduction percentage 97.5%, whereas MIC2 treated samples were able to reduce the bacterial count of such pathogen until 18th day with reduction rate 99%. These findings suggested that NIS loaded chitosan-alginate nanoparticles and OEO loaded chitosan-alginate nanoparticles exhibited an improved anticolestredial activity due to its controlled release from the nanoparticle system which in turn conferred protection to NIS and OEO from degradation.
Therefore, these promising outcomes could candidate the potential application of nisin loaded nanoparticles and OEO loaded nanoparticles in the food industry as a bio preservative agent of meat products.