Etiket Arşivleri: FE421

Yogurt Analysis ( Hakan MAVİŞ )

FE 421 FOOD MICROBIOLOGY LABORATORY

Name of student       : M. Hakan MAVİŞ

Group                            : B – 2

Name of experiment : Milk and Milk products, Yogurt Analysis

Purpose:

The purpose pf this experiment was to analyze microbiological properties of yogurt and to investigate the number of lactic acid bacteria and formation of mold and yeast.

Theory:

The effect of yogurt as a dietary supplement was investigated with regard to the gut ecosystem and lipid metabolism of 12 healthy, elderly people (78.3 +/- 9.8 years, body mass index 23.6 +/- 5.3 kg m -2, and mean +/- SD). Commercial yogurt with homogenized fruit was prepared by fermenting milk with yogurt specific cultures Lactobacillus delbrueckii ssp. bulgaricus (strain AY/CSL) and Streptococcus thermophilus (strain 9Y/CSL). The subjects consumed their usual diet (equal to 6279-6698 kJ d -1) over a 2-week baseline period (baseline start to end) and then were supplemented for 4 weeks with 250 g d -1 of fruit yogurt. The yogurt was administered in 125 g portions twice per day: at breakfast in substitution of milk and in the afternoon in substitution of tea with milk (test). At the end of the 4-week period the volunteers returned to their usual diet for a further 4 weeks (follow-up). At the end of each trial period no changes were observed in faecal water content, pH, bile acid concentration or cytolytic activity of the faecal water. Throughout the study there was significant variation neither in dietary intake of macro- and micronutrients, nor in the plasma lipids and, during the experimental period, in the counts of the total anaerobic microorganisms, bifidobacteria, lactobacilli, coliforms or enterococci. The only significant difference was observed in the clostridia counts, which decreased (P < 0.05) after the consumption of yogurt. Moreover, this effect was still evident at the end of the follow-up period. Since this last result can be considered a positive modification of the colon ecosystem, as clostridia are involved in the production of putrefactive compounds, it is possible that a yogurt-supplemented diet can maintain and/or improve the intestinal microbiota of elderly subjects.

Procedure:

  1. a) Total Count:

Firstly; from yogurt dilutions were prepared from 10-1 to 10-6 dilutions. For this, 25 g yogurt sample was weighed and added above 225 ml peptone water thus 10-1 yogurt dilution was prepared then; from 10-1 dilution 1ml was taken and it was added to 9 ml water thus 10-2 dilution was prepared. In the same manner, 10-3, 10-4, 10-5 and 10-6 dilutions were prepared. Finally; from each tube 0, 2 ml was taken with pipette and sample dilutions were put on the plate count agar (PCA) and then spread out with spread plate method and incubated at 30 oC for 1 to 3 days. After incubation number of microorganisms in gram was calculated in yogurt.

  1. b) Lactic Acid Bacteria:

At previous experiment prepared dilutions were used for this experiment. Again sample dilutions were taken 0, 2 ml and put on the mean rogosa sharp agar (MRS). Then; plates were incubated at 35 oC for 24 to 48 hours. Finally; number of lactic acid bacteria was calculated in gram.

  1. c) Mold and Yeast Count:

Again, at first experiment, preparaed dilutions were used for this analysis. In here; 0, 2 ml sample dilution was taken and was put on potato dextrose agar (PDA) and spread out with spread plate method. Then PDA was incubated at 25 oC for 2 to 5 days. Finally; number of microorganisms was calculated in gram.

MATERIALS:

  • Yogurt

  • Plate count agar

  • Mean rogosa sharp agar

  • Potato dextrose agar

  • Peptone water pipette

  • Spreader

  • Bunsen burner

  • Etuv

  • Test tube rack

  • Alcohol

RESULT and CALCULATIONS:

PCA

Total count

10-1

10-2

10-3

10-4

10-5

10-6

Open yogurt

25

5

1

0

2

0

Pasteurized yogurt

46

13

11

4

3

1

Open yogurt

19

4

1

0

4

7

PDA

Mold & Yeast

10-1

10-2

10-3

10-4

10-5

10-6

Open yogurt

TNTC

TNTC

TNTC

198

21

6

Pasteurized yogurt

1

0

0

0

0

0

Open yogurt

TNTC

TNTC

TNTC

189

16

8

 

MRS

LAB

10-1

10-2

10-3

10-4

10-5

10-6

Open yogurt

TNTC

TNTC

TNTC

TNTC

2

2

Pasteurized yogurt

TNTC

TNTC

TNTC

152

4

1

Open yogurt

TNTC

TNTC

TNTC

207

4

8

For PCA

Number of microorganisms = (46 * 101) / 0, 2 ml = 2300

For PDA

Number of microorganisms = (198 * 104) / 0, 2 ml = 9, 9*106

Number of microorganisms = (189 * 104) / 0, 2 ml = 9, 45*106

Average number of m / o’s = (9, 9*106 + 9, 45*106) / 2 = 9, 675106

For MRS

Number of microorganisms = (152 * 104) / 0, 2 ml = 7, 6*106 (pasteurized)

Number of microorganisms = (207 * 104) / 0, 2 ml = 1, 035*107 (raw)

Discussion:

In this experiment, we examined properties of microorganisms and calculated the number of microorganisms in yogurt. For this, we made three analyses. For the number of microorganisms on plate count agar, for lactic acid bacteria on mean rogosa sharp agar and for mold and yeast on potato dextrose agar were used for yogurt microbiologic analyses. In here; MRS was used to determine total number of lactic acid bacteria. PDA was used to determine the number of mold and yeast. When we diluted the yogurt sample, we used the peptone water has a great protective effect. For this, 1g peptone was dissolved in 1L of distilled water and pH was adjusted to 7, 0 and it dispenses in sufficient quantity to allow for loss during sterilization.

The end of experiment, at pasteurized yogurt 2300 microorganisms was calculated on PCA. Actually; in open yogurt more microorganisms should have been observed. On the other hand; also in here, these microorganisms were useful microorganisms like Lactobacillus bulgaricus and Streptococcus thermophilus.

On MRS, lactic acid bacteria were calculated as 7, 6*106 for pasteurized yogurt and 1, 035*107 for open yogurt.

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.