Amin Abrahim

Chitosan effects on quality properties of Greek style fresh pork sausages.

The effect of chitosan (0.5% and 1%) added individually or in combination with nitrites (150ppm) on microbiological (Total Viable Counts, Lactic acid bacteria, Pseudomonas spp., Brochothrix thermosphacta, Enterobacteriaceae, yeasts and moulds), physicochemical-chemical (pH, chemical composition, lipid oxidation) and sensory properties of fresh pork sausages stored at 4°C for 28 days was investigated. Chitosan addition resulted in significant (p<0.05) inhibition of microbial growth, while nitrites did not seem to protect sausages from microbial spoilage. A gradual reduction of nitrites was observed till the end of storage, when nitrites were almost depleted in all nitrite containing samples. The rate of lipid oxidation in fresh pork sausages was significantly decreased (p<0.05) by addition of increasing levels of chitosan, while samples containing both chitosan and nitrites showed the lowest malondialdehyde (MDA) values, indicating a synergistic antioxidative effect. Consequently, the samples containing the combination of nitrites and chitosan at any level deteriorated less rapidly and were judged as more acceptable than all the other samples.

Physicochemical, microbiological and sensory attributes for the characterization of Greek traditional sausages.

Physicochemical, microbiological and sensory analyses were performed on 67 samples of Greek traditional sausages. The following physicochemical attributes were recorded: moisture 49.17%±7.05, protein 17.62%±2.67, fat 29.74%±8.02 and ash content 2.99%±0.55, moisture/protein ratio 2.83±0.5. pH value 5.48±0.49, water activity (a(w)) 0.959±0.015, total grill losses 12.81%±5.27 and fat grill losses 9.64%±4.36. The microbial counts, expressed as log(10)cfu/g, were for aerobic plate count 8.22±0.5, lactic acid bacteria 7.45±0.66, Brochothrix thermosphacta 7.02±1.21, pseudomonads 6.88±1.33 and yeasts 5.39±1.03. Mean sensory scores, on a five-point hedonic scale, were 4.46±0.63 for appearance, 4.14±0.63 for firmness, 3.80±0.97 for flavour and 4.12±0.52 for overall quality. The discriminant analysis have shown that, based on their pH and a(w) values, 74.6% of sausages were classified as easily perishable, 19.4% as perishable and 5.9% as shelf-stable. Also, 4.4% of sausages had fat content less than 15%, 23.8% from 15 to 25%, 46.2% from 25 to 35% and 25.3% more than 35%. Principal component analysis has shown that the first two components (PC1 PC2) account for 44.1% of the total variance. PC1 was related to water activity, ash, moisture and fat content, flavour, Br. thermosphacta and pseudomonads count, and to a lesser extent to cross section quality. PC2 was related to aerobic plate count, lactic acid bacteria and moisture content.

Antibiotic resistance of Salmonella spp. and Listeria spp. isolates from traditionally made fresh sausages in Greece.

Sixty-five samples of traditionally made fresh sausages obtained from retail shops and butcher shops in northern Greece were screened for the presence of Salmonella spp. and Listeria spp. Salmonella spp. were found in 20% of the samples tested (54% Salmonella typhimurium and 46% Salmonella enteritidis). The prevalence of Listeria spp. in the samples was 26% (12% Listeria monocytogenes, 76% Listeria innocua, and 12% Listeria welshimeri). Nine of 13 Salmonella isolates were found to be resistant to ampicillin and 4 of 13 showed intermediate sensitivity; 1 of 13 was found to be resistant to chloramphenicol and 1 of 13 to tetracycline. Two strains of Salmonella typhimurum were multiresistant (resistant to ampicillin, chloramphenicol, and norfloxacin). All Listeria isolates were sensitive to the antibacterial agents tested that are commonly used for the treatment of human listeriosis.

Chemical and bacteriological characteristics of Pichtogalo Chanion cheese and mesophilic starter cultures for its production

Sixty-two samples of Pichtogalo Chanion cheese traditionally produced in Crete, a few (3 to 6) days old, were analyzed for some chemical and bacteriological characteristics. The results of physicochemical analyses were as follows: (1) moisture content 61.63% (standard deviation 4.67); (2) fat in dry matter 54.03% (SD 7.73); (3) protein content 14.23% (SD 1.72); (4) salt content 1.02% (SD 0.38); (5) water activity (aw) 0.990 (SD 0.003); and (6) pH 4.36 (SD 0.25). None of the samples yielded Salmonella spp. Listeria monocytogenes and coagulase-positive staphylococci were present in 6.45% of the samples. Bacillus cereus and sulfite-reducing clostridia were isolated from 14.51% and 40.32% of the samples, respectively. High populations of coliforms were determined in the cheese samples. In 11.3% of the samples, Escherichia coli was not detected, while 88.7% of the samples yielded E. coli most probable number levels from 1.32 to 5.66 log10/g. The log10 CFU/g counts of enterococci were 6.89 (SD 0.84), of yeasts 6.79 (SD 0.61), of molds 4.68 (SD 0.69), and of psychrotrophic bacteria 7.63 (SD 0.62). The log10 CFU/g counts of lactic acid streptococci and lactococci were 7.91 (SD 0.68) and of lactobacilli 8.11 (SD 0.65). Lactic acid bacteria, mainly mesophilic, were isolated and confirmed using API 50 CH test trips. A pasteurized mixture of ewes and goats milk was made into Pichtogalo Chanion cheese according to standard procedure at 23 degrees C, after the addition of 4% commercial mesophilic starter culture or 2%, 3%, and 4% starter culture of the isolated and confirmed lactic acid bacteria and the addition of rennet. Results of this work indicated that high quality of Pichtogalo Chanion cheese can be produced using a pasteurized mixture of ewes and goats milk and 4% (vol/vol) of mesophilic starter culture.

Isolation and Antimicrobial Resistance of Staphylococcus spp. in Freshwater Fish and Greek Marketplaces

The presence and antibiotic resistance of Staphylococcus spp. in freshwater fish and the environment of fish markets of Northern Greece were investigated. A total of 269 samples were examined, consisting of 71 rainbow trout (Oncorhynchus mykiss), 65 gibel carp (Carassius gibelio), and 133 environmental samples swabbed from various surfaces at fish markets.Staphylococcus spp. was isolated from 27% of the samples, and 16%, 9%, 0.7%, 0.4% and 0.4% were found to be positive for S. aureus, S. epidermidis, S. warneri, S. hominis-hominis, and S. haemolyticus, respectively. All isolates were examined for their susceptibility to 20 antibiotics. None of the S. aureus isolates were resistant to oxacillin and glycopeptides. Three S. epidermidis, two S. Warneri, and one S. haemolyticus isolates were resistant to oxacillin (methicillin resistant Staphylococcus, MRS). All isolates, except one, showed resistance to as many as 15 antibiotics. The population of Staphylococcus spp. in fish did not exceed 1.0 log CFU/g. Freshwater fish and the environments of retail fish markets were found to harbor multi-drug resistant staphylococci. Whether these findings present a real health risk for humans and to what extent needs to be evaluated.

Growth of Aeromonas hydrophila in the Whey Cheeses Myzithra, Anthotyros, and Manouri during Storage at 4 and 12°C

The fresh whey cheeses Myzithra, Anthotyros, and Manouri were inoculated with Aeromonas hydrophila strain NTCC 8049 (type strain) or with an A. hydrophila strain isolated from food (food isolate) at levels of 3.0 to 5.0 × 102 CFU/g of cheese and stored at 4 or 12°C. Duplicate samples of cheeses were tested for levels of A. hydrophila and pH after up to 29 days of storage. At 4°C, A. hydrophila grew in Myzithra and Anthotyros with a generation time of ca. 19 h, but no growth was observed in Manouri. In Myzithra, average maximum populations of 8.87 log CFU/g (type strain) and 8.79 log CFU/g (food isolate) were recorded after 20 and 22 days of storage at 4°C, respectively. The average maximum populations observed in Anthotyros stored at 4°C were 6.72 log CFU/g (food isolate) and 6.13 log CFU/g (type strain) and were observed after 15 and 16 days of storage, respectively. A. hydrophila grew rapidly and reached high numbers in cheeses stored at 12°C. The average generation times were 3.7 and 3.9 h (Myzithra), ...

Antimicrobial resistance profiles in Salmonella spp. and Escherichia coli isolates from turkey samples in Northern Greece

This study investigated the antimicrobial resistance in Salmonella spp. and Escherichia coli isolates recovered from 247 (225 ceca and 22 neck skins) turkey samples randomly collected from three slaughterhouses around Thessaloniki in Northern Greece. Thirty of the 31 Salmonella spp. isolates recovered from the 247 samples showed resistance to at least three antimicrobial agents of different classes (multiple resistance). The most common resistance pattern found was resistance to tetracycline, streptomycin and chloramphenicol in combination with resistance to other antimicrobials. All isolates were susceptible to cephalothin, gentamicin and ciprofloxacin. In contrast, 47.4% of the 97 E. coli isolates recovered were resistant to ciprofloxacin and 43.2% to cephalothin. Most (97.9%) of the E. coli isolates displayed a multiple resistance. The predominant resistance pattern was resistance to tetracycline, nalidixic acid, ampicillin, kanamycin and sulfamethoxazole/trimethoprim. Of particular interest was the resistance of Salmonella and E. coli isolates against tetracycline, streptomycin and nalidixic acid, and of only E. coli against ampicillin, amoxicillin, and ciprofloxacin, since they are listed as Critically Important Antimicrobials for Human Health by WHO. The results of the present study provide support to the need for improved farming practice and for more prudent use of antimicrobial agents in the turkey sector.

The influence of mannan oligosaccharides, acidifiers and their combination on caecal microflora of Japanese quail (Coturnix japonica).

The aim of this study was to investigate the effects of the dietary supplementation of mannan oligosaccharides (MOS) extracted from yeast Saccharomyces cerevisiae, acidifiers-calcium formate (CF), calcium propionate (CP)- and their combination on the caecal microflora of Japanese quail (Coturnix japonica). Four hundred and fifty 1-day old quail where divided in six groups with three replicates each. One group that served as control received the basal diet. The five experimental diets consisted of the basal diet to which either 1 g MOS/kg, or 6 g CF/kg, or 6 g CP/kg, or 1 g MOS plus 6 g CF/kg or 1 g MOS plus 6 g CP/kg were added. The body weight was examined at weekly intervals and mortality was recorded daily. At days 21 and 42 of age, the total count of aerobic bacteria, lactic acid bacteria, enterobacteriaceae and coliforms in the caecal content of one bird of each replicate was determined. Also, at day 42 of age, two birds of each replicate were slaughtered and their carcass weight was determined. The results showed that MOS significantly (P ≤ 0.050) increased the total aerobic plate and lactic acid bacteria counts on day 21. Furthermore, CP significantly (P ≤ 0.050) decreased the total aerobic plate and lactic acid bacteria counts compared to controls on day 21. Significant interaction between MOS and acidifiers was noticed on total aerobic plate count on day 21. No significant (P > 0.050) difference was found in the caecal microflora on day 42. Finally, no significant (P > 0.050) difference was noticed on mortality, body and carcass weight.