Laboratory‎ > ‎Seafood ( Hakan MAVİŞ )

FE 421 FOOD MICROBIOLOGY LABORATORY

Name of student : M. Hakan MAVİŞ

Group : B – 2

Name of experiment : Seafood

PURPOSE:

The purpose of this experiment was to investigate microbiological affectivities of fish.

THEORY:

International competitiveness requires optimal productivity, quality and value, and the development of new products from traditional raw materials, underutilized species and waste streams. The productivity and competitiveness of seafood processing depends not only on the sources and costs of raw materials, but also on other costly resources: energy, water, labor and waterfront space. Energy equipment for thermal operations (refrigeration, cooking and retorting) is tremendous, yet opportunities exist for conservation through energy and water audits and demonstrating new technologies at processing plants. Solid waste disposal is a mounting problem for the industry as coastal populations and environmental sensitivities increase. This problem by developing enzymatic and microbial methods of hydrolysate manufacture for feed and fertilizer production, and improving manufacturing methods and uses of dried meals.

Seafood is among the most expensive items in the American diet due to the high costs of catching, transporting, processing and storing this delicate commodity. Although profit margins are small, improved post-harvest technologies offer opportunities to increase product quality and profits. Seafood muscle tissues are the most valuable component of seafood products—they have many desirable properties due to their water- and fat-binding traits, which can be enhanced by non-seafood additives and novel processing techniques. Ready-to-cook and ready-to-eat seafood products require processing and storage that can reduce product quality. A better understanding of the chemical and physical properties of seafood muscle components could minimize these effects. Many fish species are not widely consumed for food because they degrade rapidly. Improved storage and processing techniques would help; but because fish and shellfish are highly variable in their physiology, their properties need to be studied by species. New enzymes, enzyme inhibitors and other “active” proteins, such as antifreeze proteins, could be isolated from seafood sources and used to add value to other seafood.

MATERIALS:

  • Tubes

  • Fish

  • PCA (plate count agar)

  • Bunsen burner

  • Spreader

  • Sterile water

  • Alcohol

  • Etuv

  • Pipette

  • Test tube rack

PROCEDURE:

Firstly; a sterile swab was taken and it was plunged into 0,1 % peptone water for soaking then swab was spread on surface of fish about 10 cm2, swab was put into 10 ml 0,1 % peptone water after breaking tip off of swab then. Swab and peptone water were shaken then 0,5 ml sample was taken from tube containing swab and peptone water and inoculated to PCA and incubated at 37 oC for 24 hours.

Secondly; coliform test was applied on fish. 0,5 ml sample was taken and inoculated to violet red bile agar (VRBA) and then incubated at 37 oC for 48 hours. Finally; number of microorganisms was calculated in 1 cm2.

RESULTS and CALCULATIONS:

Total count

Coliform test

Group 1

216

11

Group 2

177

7

Group 3

244

15

Group 4

152

40

Group 5

202

24

Group 6

200

108

Group 7

147

17

Group 8

90

7

Group 9

110

5

These values were in 10cm2 and for 1cm2:

# of m/o’ s = 216*1 cm2 / 10cm2 = 22

# of m/o’ s = 177*1 cm2 / 10cm2 = 18

# of m/o’ s = 244*1 cm2 / 10cm2 = 24

# of m/o’ s = 152*1 cm2 / 10cm2 = 15

# of m/o’ s = 202*1 cm2 / 10cm2 = 20

# of m/o’ s = 200*1 cm2 / 10cm2 = 20

# of m/o’ s = 147*1 cm2 / 10cm2 = 15

# of m/o’ s =   90*1 cm2 / 10cm2 = 9

# of m/o’ s = 110*1 cm2 / 10cm2 = 11

Coliform test:

# of m/o’ s =   11*1 cm2 / 10cm2 = 1

# of m/o’ s =     7*1 cm2 / 10cm2 = 1

# of m/o’ s =   15*1 cm2 / 10cm2 = 2

# of m/o’ s =   40*1 cm2 / 10cm2 = 4

# of m/o’ s =   24*1 cm2 / 10cm2 = 2

# of m/o’ s = 108*1 cm2 / 10cm2 = 11

# of m/o’ s =   17*1 cm2 / 10cm2 = 2

# of m/o’ s =     7*1 cm2 / 10cm2 = 1

# of m/o’ s =     5*1 cm2 / 10cm2 = 1

DISCUSSION:

In this experiment we studied the seafood and for this we used a fish, and at 10cm2 number of microorganisms were examined. In order to analyze we used swab. Swab is a sterile loop. Swab was spread the surface of fish then heat part or cotton part was broken down so as to not touch our hand, because on our hand some microorganisms may be and these microorganisms with swab together can be put in 10 ml sterile water. If it is so, our results can be false so we must care when this process was applied.

Living fish carries gram negative psychrotropic bacteria on their surface and also fresh fish carries 102 or 103 bacteria per 1cm2 on surface, also our result shows in results and calculation part. Stale fish can be to include more microorganisms and these microorganisms can harm to human health.

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