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PREVALENCE OF STAPHYLOCOCCUS AUREUS IN FISH PROCESSING FACTORY

Кarine Grigoryan, Grigor Badalyan, Djulietta Andriasyan

ABSTRACT The aim of the presented work was the risk assessment of distribution and prevalence of Staphylococcus aureus during processing of cold-smoked fish. There were totally analyzed 80 samples of fish and 50 swab samples at all stages of the processing. Staphylococcus aureus was detected in 74% of analyzed samples. Brining stage was the important critical control point in cold-smoked fish proceesing.

Keywords: Staphylococcus aureus, cold -smoked fish, brine

INTRODUCTION

Safety of fish products and their quality assurance is one

of the main problems of food industry today.

The presence

or

absence

of

foodborn

pathogens

in

a

fish

product

is

a

function

of

the

harvest

environment,

sanitary

conditions,

and the

practices associated with equipment and personnel in processing environment (FDA, 2001; Huss, 2003).

S. chromogenes. High Staph. aureus counts (104-105.g-1) occurred and reached 5% of total staphylococci counts. Up to 104 Staph. aureus cells.g-1can be tolerated in ready-to- eat seafoods (FDA, 2004). Enterotoxin production is typically associated with coagulase-positive Staph. aureus when cell populations are 105.g-1 (Jablonski and Bohach, 1997).

The handling of fish products

process

involves

a

risk

during the manufacturing

of

contamination

by

The aim of the study was the assessment of prevalence of Staph. aureus during manufacturing of cold smoked trout.

Staphylococcus aureus, a Gram-positive microorganism causing foodborne human intoxication (Ash, 1997; Shena et al., 2007). These bacteria are salt-tolerant and therefore can contaminate all cured preparations such as cold smoked fish, caviar and fish-based preserves (Hayes, 1995). Fish contains large amount of proteins and their breakdown into amino acids support the growth of Staph. aureus. Staphylococcus spp. may be isolated from newly caught fish, especially in warm waters (Gram and Huss, 2000). Staphylococcus is not found in the normal microflora of fish. This microorganism could be associated with salt (Hansen et al., 1995) or the raw fish (Ferreira et al, 2007) used in the processing. Contamination of fish products through contaminated surfaces has also been observed in many cases (Reij et al., 2003). According to Basti et al., (2003) some kinds of salt smoked fish may be considered as risk of L. monocytogenes and Staph. aureus infection and intoxication for Iranian consumers respectively. An assessment on the potential microbiological hazard associated with smoked fish fillets under refrigerated storage was made. Staph. aureus survived better at both storage temperatures (T= -100C - 50C) (Mariappan et al., 2004). According to Enclund (2004) contamination of fish by pathogens particularly

such

as

Staphylococcus

aureus,

Campylobacter

jejuni,

Escherichia

coli

0157:H7,

Vibrio

parahaemolyticus,

Yersinia enterocolitica, and Listeria occur prior to harvest, during

monocytogenes, may capture, processing,

distribution shown, that

and/or storage. Himelbloom’s studies have strips handled without gloves contained 10 5

MATERIAL AND METHODS Sampling

There were totally analyzed 80 samples of fish and 50 swab samples. Fish samples were taken from every step of processing: receiving raw materials, cleaning, separation of fillets, brining, cold smoking, packaging, storing. All samples of

fish

were

collected

and

placed

in

sterile

polyethylene

bags, transported to laboratory and upon arrival (ISO, 6887-3:2003). taken from all surfaces and tools by 651, Hi Media) (APHA,1992). Detection of Staph. aureus.

analyzed immediately Swab samples were Transport swabs (MS

For determination of species of Staph. aureus, 10g of each samples of fish fillets were removed aseptically using a scalpel and forceps, and then transferred to sterile tubes with 90ml Baird Staphylococcus Enrichment Broth Salt (M-1091, Hi media) (ISO, 68881-1999). Tubes were incubated for 24 hours at 370C. Then samples from every tube were taken with microbiological loop and spread on the surface of solid media Baird-Parker agar (M-043, Hi Media) and Mannitol salt agar (MM-118, Hi Media). All plates were examined visually for typical colony types and morphological characteristics. For confirmation of S. aureus strains Hicrom Aureus agar (M1468, Hi Media) was used and following biochemical tests were provided. Those results were confirmed by HiStaph TM- identification kit (Hi Media). For confirmation of DNAase

reaction

of

Staphylococcus

aureus,

3M

Petrifilm

Rapid

Staphylococcus

aureus/g.

Sanitary handling and air

quality

control

will

enhance

seafood

safety

while

maintaining

product quality attributes. (Himelbloom et al., 1998).

Staphylococcus aureus Count used. Physical-chemical analysis

plate

(3MPetriFilmTM)

was

In smoked and dried king salmon processed by Alaska Natives, coagulase-negative Staphylococcus species comprised 75% of the staphylococci isolates (Himelbloom et al., 1998). Most of the species of staphylococci, that have been isolated from fish are coagulase negative, namely, Staphylococcus epidermidis, S. xylosus, S. lentus, S. capitis, S. lugdunensis, S. hominis, S. warneri, S. cohnii,

Moisture was determined

by drying

oven

with

the plates

being

weight

until

constant

weight

was

reached

AOAC

950.46B ; Novoa et al., 1994). Definition of

pH was spent

with

pH-meter (OAKTON, USA). Determination of aw of

samples

was

spent

with

AquaLab

(Decagon

Devices,

Pullman,WA,USA). Concentration of sodium chloride was

ročník 4

25

2/2010

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