Study on Efficiency of Wooden Cutting Board Cleaning Techniques | Oral Presentation

26BI04-02

SCIENCE PROJECT MWITS Science Fair 2018

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Nowadays, people live with hastiness which include the quick eating style.

One of the most popular easy-to-eat food for Thais is the “Hainanese chicken rice�

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Particularly, the wooden chopping boards are full of moisture and nutrients. “Thus, the boards become the suitable place for microbes to grow�

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Therefore, the most popular cleaning methods the Thais use are tapping with

• 3% v/v H2O2 solution • 20% w/v saline solution • 5% v/v CH3COOH solution and most used woods to make cutting boards in Thailand are

• • •

Rubber wood (Hevea brasiliensis) Tamarind wood (Tamarindus indica) Wattle (Acacia auriculiformis)

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• Evaluate the amount of bacterial growth on each type of wood used to make cutting boards. • Compare each cleaning method efficiency.

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Step

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Finding the most suitable dilution factor for the experiments

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I Figure 1 Cut chicken sample

Figure 2 Mixed the chicken sample

into 25 grams

with 225 ml sterile water

Figure 3 Shook for

10 seconds 11

Using 1 ml Volumetric Pipette

3rd Dilution

1 ml Sample

2nd Dilution

1st Dilution

1 ml Sample

I Did the spread plate and pour plate method of every dilution factor

Figure 4 Prepared

chicken solution in previous step is in 1:10 Dilution 12

1:1000

3rd Dilution

1:100

2nd Dilution

1:10

1st Dilution

I Incubated at 37°C for 24 hours

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Spread Plate and Pour Plate Method

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Figure 5 Characteristic of colonies in

Figure 6 Characteristic of colonies in

boiled chicken at 1:100 dilution

boiled chicken at 1:1000 dilution 15

Results claim that 1/100 dilution is the most suitable dilution factor Figure 7 Number of colonies from each dilution factor

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Step

II

Simulating the used wood samples’ surface which is exposed to chicken solution

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1 ml Sample Using 1 ml Volumetric Pipette

2nd Dilution

1st Dilution

II From the previous result, it showed that the 1:100 Dilution was the most suitable dilution factor

Prepared chicken solution is in 1:10 Dilution 18

2nd Dilution

Filter Paper

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1:100 Dilution

Firmly placed a filter paper in each petri dish

Dropped the diluted solution on to a filter paper, approximately 35 droplets for a filter paper to be all wet Figure 8

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II Petri dish with filter paper, wet with chicken solution

Figure 9 Placed

12 pieces of wood per type on to a filter paper and seal the petri dish with Parafilm

Stored at room temperature for 24 hours 20

II Figure 10 Sealed

petri dishes 21

Step

III

Evaluating each cleaning method efficiencies

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III NaCl 20% w/v

H2O2 3% v/v

CH3COOH 5% v/v

Figure 11 Prepared

cleaning reagents

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III

•1st Set = Control set, which is tapped only with sterile water •2nd Set = tapped with H2O2 3% v/v •3rd Set = tapped with NaCl 20% w/v •4th Set = tapped with CH3COOH 5% v/v

*2nd,3rd, and 4th set should be done with control set under the same condition*

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H2O2 3% v/v

III

Figure 12 Cleaning

wood surface

Sterile water

Gently place a filter paper full of cleaning reagents on to a petri dish CH3COOH 5% v/v *Do not let each reagents mix with each other*

NaCl 20% w/v 25

III Rest for 1 minute

Placed the contaminated wood on to each filter paper 26

III

Figure 13 Wood sample

Sterile water CH3COOH 5% v/v Gently placed the cleaned wood samples on the NA with label shown

on NA

H2O2 3% v/v NaCl 20% w/v

Incubated at 37°C for 24 hours 27

=

−

S = Number of colonies in stock culture E = Number of colonies on cleaned wood surface

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Figure 14 Tapped

contaminated tamarind wood from each cleaning method

Figure 15 Tapped

contaminated rubber wood from each cleaning method

Figure 16 Tapped

contaminated wattle from each cleaning method

A

B

A

B

A

B

C

D

C

D

C

D

Wattle (Acacia auriculiformis)

Rubber Wood (Hevea brasiliensis)

Tamarind Wood (Tamarindus indica)

A = Sterile water, B = 3% v/v H2O2, C = 5% v/v CH3COOH, and D = 20% w/v NaCl

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Percent Cleaning Efficiency (%)

100

80 60 40

20 0

Sterile Water

H2O2 3% v/v

NaCl 20% w/v

Cleaning Techniques

Figure 17 Cleaning efficiency results

CH3COOH 5% v/v

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Bacteria will grow better on a coarser wood surface.

Rubber wood has the coarsest texture

(AK, CLIVER and KASPAR, 1994)

Did the experiment

5% v/v CH3COOH solution is the best cleaning solution Wattle

Tamarind wood 33

20% w/v NaCl solution is the worst cleaning solution (can inhibit the bacterial growth the least)

Most bacteria in the chicken sample can be tolerate more than 20% salinity (halotolerant bacteria)

Staphylococcus Bacillus

Bacillus

(Foodnetworksolution.com, 2017)

Figure 18 Life in saline environment

Staphylococcus 34

3% v/v H2O2 solution can inhibit the anaerobe bacteria But most bacteria in foods are aerobic bacteria which has catalase that can eliminate H2O2 (สุภเวชยและวงลรจิตร, 1997)

Figure 19 Detoxification of H2O2 and superoxide anion

Therefore, in the chicken sample the aerobic bacteria can still grow.

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5% v/v CH3COOH solution approximately has pH 3

But the suitable pH range for the normal bacteria to grow is about pH 6.5-7.0 (Prescott, Harley, and Klein, 2008) Figure 20 approximate pH ranges

5% v/v CH3COOH solution is the best cleaning solution

for the growth of the different classes of pH-specific prokaryotes

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Rubber wood is the best wood at inhibiting bacterial growth.

5% v/v CH3COOH solution 5% v/v CH3COOH solution is the best cleaning solution

Followed by tamarind wood and wattle

3% v/v H2O2 solution

20% w/v NaCl solution

Followed by 3% v/v H2O2 and 20% w/v NaCl solution 38

Akkaoui, A., Care, S., & Vandamme, M. (2017). Experimental and microchemical analysis of the elastic properties of wood-aggregate concrete, Construction and Building Materials, 134, 346-357.

Fakruddin, Md., & Mannan, K., S. (2013). Methods for Analyzing Diversity of Microbial Communities in Natural Environments, Ceylon Journal of Science, 42(1), 19-33. doi:10.4038/cjsbs.v42i1.5896 Reeb, E., J. (1997). Drying Wood. Lexington, Kentucky: The University of Kentucky Cooperative Extension Service.

Jiang, J., Wang, J., Zhang, X., & Wolcott, M. (2017). Microstructure change in wood cell wall fracture from mechanical pretreatment and its influence on enzymatic hydrolysis, Industrial Crops and Products, 97, 498-508.

Milling, A., Kehr, R., Wulf, A., & Smalla, K. (2005). Survival of bacteria on wood and plastic particles: Dependence on wood species and environmental conditions, Holzforschung, 59, 72-81. doi:10.1515/HF.2005.012 Ramage, M., H. et al. (2017). The wood from the trees: The use of timber in construction, Renewable and Sustainable Energy Review, 68, 333-359.

Neth, Kristen, Girard, David, and Albrecht, Julie A. (2008). Determination of Bioflms on Plastic Cuting Boards, RURLS: Review of Undergraduate Research in Agricultural and Life Sciences: Vol. 3: Iss. 1, Article 5.

AK., O., Nese, Cliver, O., Dean, and Kaspar, W., Charles (1994). Cutting Boards of Plastic and Contaminated Experimentally with Bacteria, Journal of Food Protection, 57, 16-22.

Foodnetworksolution.com. (2017). แบคทีเรียที่สําคัญในอาหาร - Food Wiki | Food Network Solution. [online] Available at: http://www.foodnetworksolution.com/wiki/word/3708/แบคทีเรียที่สําคัญใน อาหาร [Accessed 20 Dec. 2017].

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We gratefully thank to all teachers in the department of biology, Mahidol Wittayanusorn School who gave all supports and advice to our group, Wachirakorn’s uncle who spent his time to find woods and processed them for us, Natnicha’s relatives who found rubber wood for us, Pakin for his effort to cut wood by his own hands, our friends who gave encouragement, and our beloved advisor, Somruthai Kaeoboon who supported our group in every situation and motivated us to do something inspirational.

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2 cm

1 cm 1 cm

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วางลงบน Petri Dish เพื่อเตรียมการอบ 45

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Filter Paper

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