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Abstract
One hundred fifty three of fish & canned fish samples [113 of canned fish products , various kinds of imported and local canned fish , and 40 of imported chilled and frozen fish] were collected and examined physically, pH and bacteriologically.
Physical examination of the samples revealed that:
- Physically, the results showed that all samples of local canned sardine, and
• imported canned mackerel did not fulfilled the legal requirements . As their drained weights were less than 70% of the net weight. The averages of the drained weight percents of imported canned tuna, local canned sardine, imported
• canned sardine and imported canned mackerel were 72.1%, 55.9% , 75.2 %and 67.4 % ,respectively.
• 2- Two samples of imported canned sardine had blackish discoloration on the inner surface of the can which may be a result of iron sulphide.
3-All samples of local and imported canned sardine contained spines but But it is normal because [ESSs canned sardine & mackerel] stated that whole fish can be used but without head and gills.
• 4- All canned fish samples were rust free except in local canned sardine, 2 samples (10 % of local canned sardine) had inner rust whereas 5 samples (25% of local canned sardine ) had external rust.
5- All examined samples of imported chilled and frozen fish were physically accepted except 5 samples of chilled fish showed early signs of decomposition (yellowish discoloration of the gills) and one sample of frozen fish showed signs of decomposition; their pH values were within the limit.
pH values:
- The means of the pH values of imported caimed tuna, local canned sardine, imported canned sardine and imported canned mackerel were 5.56 , 5.57, 6.04 and 6.31, respectively.
2- The means of the pH values of imported chilled and frozen fish were 6.05 and 6.04 , respectively.
Bacteriologically.
1-81.4% of all of the examined samples of canned fish products appeared to be
• sterile.
• 2- Other cans had low total aerobic bacteria counts .With exception , only one
• sample of local canned sardine, their count was very high ( 3Xl04 ). whereas the means of the total aerobic bacteria counts of imported canned tuna , local
canned sardine, imported canned sardine and imported canned mackerel were l.7X10, 1.5X103, 2.2X10 and 9 CFU/g ,respectively.
3- The total aerobic bacteria counts of imported chilled and frozen fish revealed that 15% and 20 % of imported chilled and frozen fish, their counts were less than 10 CFU/g.
4- Only , one sample of each of imported chilled and frozen fish, their counts were above the legal requirement for aerobic plate count in ESSs , where their counts were 2.2X106 and 5X106, respectively . whereas the means of the total aerobic bacteria counts of imported chilled and frozen fish were 1.4X105 and 2.6X105, CFU/g ,respectively.
5-The number of cans that showed negative growth in Baird Parker agar are 103 cans (91% of all the examined cans).
6- The means of presumptive total staphyloccocus aureus count of imported
canned tuna, local canned sardine, imported canned sardine and imported canned mackerel were 2.9X102, 2X10, 1.6Xl02 and l.7X102 CFU/g ,respectively.
• 7- Only one sample (imported canned sardine ) was coagulase +ve.
So the incidence of the isolated coagulase +ve Staphylococcus aureus among
all examined canned fish samples was 0.88%.
8- In all examined canned fish samples , the counts of Clostridium perfringens were less than 1OCFU I gram sample.
9- In ill examined canned fish samples , listeria monocytogenes and Salmonella spp. could not be detected in 25 grams of each samples.
10-Also, in all the examined samples of chilled and frozen fish samples, Salmonella spp. could not be detected in 25 grams of each samples.
11-70% and 90% of all the examined samples of chilled and frozen samples their coliforms counts were less than 10 CFU/g. Only, one of each of chilled and frQ.Len samples were over the permissible limit; where the maximum values of chilled
• and frozen samples were 2.7Xl02 CFUIg and 3.3Xl02 CFUIg , respectively.
12- The Enterobacteriaceae and the coliforms counts of all the examined samples of imported canned fish products were less than 10 CFU / gram.
13- In local canned sardine , one sample its Enterobacteriaceae and the coliforms presumptive counts were 1 .7X1 o4 and 1. lxi o4 , respectively. And the
• remaining sample their counts were less than 10 CFU / gram.
.14-By further biochemical tests, the isolated strain from VRBG & VRBL is not related to family Enterobacteriaceae.
15- And biochemical tests showed that the isolated strain which grew on VRIBG
& VRBL is Aeromonas hyDROPhila which made haemolysis to sheep RBCs.
By PCR technique, the isolated strain was Aeromonas hyDROPisila AbA negative and HZyA positive.
16- Identification of some isolated bacteria grown on pbte count agar revealed that the two strains were aerobic spore former bacteria ( Anthracoid ). One strain was Bacillus subtilis which was isolated from imported canned tuna and the other was Bacillus amyloliquefaciens which was isolated from imported canned sardine.
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