Staphylococcus aureus is a common cause of food-borne disease worldwide and food poisoning. This study reports the effect of nisin (0, 10 and 12.5 ppm) against Staphylococcus aureus in manufactured kareish cheese. Nisin was effective in reducing S. aureus count in cheese; a reduction of S. aureus count was observed from the 2nd day of storage period. S. aureus in kareish cheese decreased gradually from 4x108 to (8×107, 6.5×107, 5.8×107 CFU/gm.) in the 1st week till reached at the end of storage period of the 4th week to (4 ×104, 1.1×103, 1×102 CFU/gm.) for cheese containing (0, 10 and 12.5 ppm) of nisin, respectively during manufacture and storage for a month in the refrigerator at 4 ˚C. The data obtained in this study suggested that the use of nisin-containing cheese can be an effective method of controlling the growth and multiplication of S. aureus in cheese.

Objectives: The objective of this study was to evaluate the impact of the antimicrobials nisin and lysozyme to control the growth of spoilage bacteria of pasteurized milk during cold storage. Materials and Methods: Nisin, lysozyme, and a mixture of them were inoculated into freshly pasteurized milk at 500 IU/ml concentrations each. The acidity, sensory evaluation, and bacteri¬ological quality of the treated pasteurized milk samples were examined at zero time and every 3 days till the samples showed the signs of spoilage, that were checked every day. Results: Obtained results showed that there was a slight increase of the titratable acidity of the control and treated samples during refrigerated storage, but the acidity increase was significantly lower in samples containing lysosomes and/or nisin than the control samples. Nisin and lyso¬zyme at 500 IU/ml concentration possessed inhibitory effect on the total bacterial, aerobic spore-formers, and psychrotrophic bacterial counts and extended the shelf-life of the treated samples. The efficacy of nisin 500 IU/ml combined with lysozyme 500 U/ml was assessed and synergistic activity has been detected, that was expressed in the form of higher inhibitory effect and extend¬ing the shelf-life of the samples up to 15 days at cold storage. Moreover, the sensory evaluation showed that nisin and lysozyme does not affect the acceptability of the examined samples. Conclusion: The obtained data indicate that nisin and lysozyme have the potential to enhance the post-process bacteriological safety of pasteurized milk during the storage period and could aid in the elimination of post-process contamination and prolong its shelf-life. [J Adv Vet Anim Res 2019; 6(3.000): 403-408]

Replacing of sodium nitrite from meat processing is a new promising advance in clean label meat products. The current article explored the positive effects of total replacement of sodium nitrite with a combined antimicrobial and antioxidant mixture comprised of 400 ppm nisin (N), 25 ppm Nano sized zinc oxide (Z), 1% chitosan (C) and 1% roselle extract (R) on proximate and fatty acid composition, cooking loss, color analysis and sensory profile of beef sausage. Four types of beef sausage were prepared as following: NT sausage samples as control positive group containing 120 ppm sodium nitrite, NCR samples (400 ppm N, 1% C and 1% R), ZCR (25 ppm Z, 1% C and 1% R) and NZCR samples containing (400 ppm N, 25 ppm Z, 1% C 5and 1% R). The outcomes of the study displayed that there was no significant difference (P > 0.01) in proximate composition of control (NT) and reformulated (NCR, ZCR and NZCR) samples. Concerning fatty acid profiling, saturated (SFA) and monounsaturated fatty acids (MUFA) were the predominant portions in all sausage types and oleic acid was the prevalent one, moreover, reformulated sausages exhibited lower SFA and higher MUFA and PUFA improving fat quality of reformulated beef sausage. A significant difference in cooking loss percentage was observed in NZCR sausage samples compared to other sausages. Noteworthy, cooked reformulated sausages kept their red color after cooking and their a* values were close to those of NT. Sensory assessment (odor, taste and overall acceptance) of reformulated sausages were higher than NT especially for NZCR that recorded the highest scores. Overall, our findings established that combination of antimicrobials (nisin and Nano sized ZnO), antioxidant (chitosan) along with Roselle extract (for red color enhancement) could be potentially applied as a possible nitrite replacer to produce healthier product free from sodium nitrite.

Contamination of milk and dairy products with spoilage and pathogenic microorganisms is a common problem worldwide. Therefore, this study was conducted on 200 samples (milk, Kareish cheese, Damietta cheese, and plain yoghurt, 50 of each) collected from Zagazig City, Sharkia, Egypt to be examined bacteriologically to isolate and identify the multi-drug resistant Pseudomonas aeruginosa as well as some reduction trials on cold stored soft cheese using some natural compounds including the essential oil (EO) of Clove (0.01%, 0.1%) and Nigella Sativa (NS 0.5%, 1%), in addition to Nisin (10 ppm 12.5 ppm). The obtained results revealed the pseudomonas aeruginosa prevalence in the examined milk and dairy product samples was 45(22.5%); 24(48%) from raw milk samples, 8(16%) from yoghurt, 9(18%) from soft cheese and 4(8%) from kareish cheese. The isolated Pseudomonas aeruginosa harbored some antibiotic-resistant genes including blaTEM, blaSHV, ermB, and Mcr1 genes, while blaOXA-1 failed to be detected, so it was resistant to different types of antimicrobial agents. The multiple antibiotic resistance index (MAR) of the isolated strains was 0.500. Clove (0.01%, 0.1%) and Nigella Sativa (NS 0.5%, 1%), in addition to Nisin (10 ppm, 12.5 ppm) had an antibacterial effect against Pseudomonas aeruginosa compared with control samples and acted as good preservatives that extended the storage period and shelf life of soft cheese up to thirty days.

Nitrite is a vital preservative widely used in meat processing. Carcinogenic N-nitroso compounds discovered in processed meat products became serious impacts negatively affect meat industry. The present study provided a nitrite free fresh sausage with a novel method to substitute nitrite with a mixture consisted of (400 ppm nisin+25 ppm Zinc oxide nanoparticles+ 1% Hibiscus sabdariffa extract +1% chitosan) employing nisin (N) and Zinc oxide nanoparticles (ZON) as antimicrobials, chitosan (C) as antioxidant and H. sabdariffa extract (H) for color improving. In vitro antibacterial activity of nisin and ZON against Clostridium perfringens reference strain was estimated using agar well diffusion test. H. sabdariffa extract was evaluated for its phenolic and flavonoid contents as well as its phytochemical profile was analyzed using HPLC. Four variants of fresh sausage with different treatments were prepared: Nitrite (NT) treated, (N.C.H), (ZON.C.H) and (N.ZON.C.H), packed in polyethylene bags and kept in a refrigerator at 4 ?C. Samples were examined to assess their pH, microbiological evaluation (aerobic plate, Enterobacteriaceae, yeast and mold counts), also, sensory assessment and shelf life were evaluated. Results exhibited that nisin and ZON have potent antibacterial activity against Cl. perfringens with inhibition zone of 30 mm and 15 mm compared to 30 mm of sodium nitrite. Hibiscus extract manifested a high phenolic content about 27.213 mg Gallic acid /g, 2.896 mg QE/g for flavonoids and about 19 main phenolic compounds were detected by HPLC. Results exhibited that N.ZON.C.H group samples showed the lowest pH values, APC, Enterobacteriaceae, yeast and mold counts among sausage variants. Regarding shelf life and sensory evaluation, as expected, N.ZON.C.H showed the highest sensory scores and shelf life (18 days) followed by N.C.H and ZON.C.H that remained accepted till 15th and finally NT till 12th day of cold storage. Results suggested that combination of nisin, ZON, chitosan and H. sabdariffa extract would be a promising new strategy to replace sodium nitrite and improve safety and quality of fresh sausage.