uKnow and the Secret Life of Yogurt

Tikhon S. Kozlov

Urbana Middle School

Ijamsville, Maryland, 21754, USA

Presented at Frederick County Science and Engineering Fair

on March 20, 2021

Project: MS-MCR01

INTRODUCTION

• Did you know that 99% of microbes around us are good, and only less than 1% cause diseases?
• Gut of a healthy human contains 100 trillion of microorganisms (the so-called normal microflora or microbiota)
• These bacteria live in a symbiotic relationship with the host. The type of this symbiosis is mutualism because bacteria use the host as their source of nutrition, while the host benefits from bacteria’s help to digest food
• Changes in microflora are associated with some diseases (e.g., Crohn’s disease, Inflammatory Bowel Syndrome, Obesity)
• Humans source their good microflora from food
• Consumption of fermented products such as yogurts, pickles, Kombucha is recommended for a dietary source of probiotics

Dietary Sources of Probiotics

INTRODUCTION (continues…)

• Bacteria in yogurt cultures digest milk sugar lactose; the result of this digestion is the formation of lactic acid, which changes the milk’s pH to acidic and makes the milk curd

• But…are all yogurts good for your gut? How do consumers know if a yogurt they see on shelves in a grocery store would supply good bacteria to their gut or simply serve a source of calories and nutrients (protein, fat, carbs)
• To answer these important questions and help people select yogurts with good source of probiotics, I conducted my project

Research Questions, Hypothesis, Goals

• Questions – Do all yogurts have an equal number of live bacteria beneficial to a human? Does the number of live cells correlate with the pH of yogurt? How can we help consumers to understand if their yogurt contains enough good microflora or it is simply a source of proteins, fats, and carbohydrates?

• Engineering Goals:

1) Estimate number of live bacteria in yogurts of different brands and different types

2) Measure pH of yogurts of different brands and different types

3) Correlate the number of live bacteria to pH

4) Create a new app, uKnow

• Hypothesis- there may be a difference in live bacteria between organic and non-organic yogurt, between flavored and plain yogurt. Flavored yogurts contain more sugar than plain yogurts; bacteria would consume the sugar faster and starve so there would be fewer live bacteria in flavored yogurt than in plain yogurt

METHODS

5 Plain Yogurts from 5 Brands

Organic

Not Organic

0.9 mL Sterile water

0.1 mL Yogurt

0.02 mL diluted yogurt

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Agar plate

Incubate 24 hours and count colonies

• Dip a strip of pH paper into yogurt
• Remove access yogurt with paper towel
• Compare the strip color to the color code on the box to decode the pH

Experiment 1 (repeat 2 times)

Experiment 2

Analyze Data

Create new app

uKnow

Android Studio

RESULTS

• Siggi’s brand had more live bacteria than Two Good and Giant brands
• Plain yogurt had more live bacteria than flavored yogurt in all brands

• Siggi’s yogurt had more live bacteria than Two Good and Giant in the non-organic group
• Organic yogurt had more live bacteria than non-organic yogurt

Each thick bar shows average number of colonies

Each thin (T-looking) bar is the error bar

RESULTS (continue…)

Activia Brand had the highest number of live bacteria than other brands

RESULTS (continue…)

• The pH of most yogurts was 4
• The pH of White Mountain yogurt was 3; this yogurt is more acidic
• The pH of Giant and Yoplait yogurts was 5; these yogurts are less acidic

*This data may be inaccurate: due to the large number of colonies that were transparent rather than white, I had to split the plate into sections and count colonies in each section, then sum them up

RESULTS (end of project)

I used Android Studio to create the app uKnow

This is my virtual device with uKnow app

DISCUSSION

• All yogurts are good and contain live bacteria
• Most yogurts have pH 4. The pH reflects the concentration of hydrogen ions. The higher the concentration of hydrogen ions the lower the pH
• Yogurts are expected to have low pH because they contain lactic acid
• The pH 3 (more acidic) corresponds to the White Mountain Organic Plain yogurt with the highest number of live bacterial cells
• The pH 5 (less acidic) corresponds to yogurts with low number of live bacteria. These yogurts are flavored and have added sugar. Perhaps, bacteria consumed all sugar and died earlier. It is also possible that flavor in these yogurts inhibits bacterial growth
• Measuring the pH of yogurt is easy with pH paper which is very inexpensive
• I created a prototype app using Android Studio. The uKnow app still needs work to improve the appearance. I wish I knew the expert I could ask a couple of questions. I am also interested in doing an internship in a company that uses Android Studio so that I could better understand how to use it
• Once improved and finalized, the uKnow app could help people to bypass laborious microbiology experiments to determine which yogurt has the highest number of live bacteria

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CONCLUSIONS

• Thousands of invisible microbes are present in all yogurts
• Plain or flavored? Organic or non-organic? The answers to these questions depend on the personal preference for flavor and texture, and also on the price
• If someone is interested in probiotic value of yogurt, the best choices are plain organic yogurt White Mountain and Cherry-flavored yogurt Activia
• uKnow could help consumers without knowledge of microbiology to select a good probiotic yogurt based on the yogurt’s pH

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REFERENCES

• https://www.gutmicrobiotaforhealth.com/about-gut-microbiota-info/#:~:text=In%20an%20individual%20weighing%2070kg,of%20their%20cells%20put%20together

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• Fernandez MA, Marette A. Potential Health Benefits of Combining Yogurt and Fruits Based on Their Probiotic and Prebiotic Properties. Adv Nutr. 2017 Jan 17;8(1):155S-164S.

• Kok CR, Hutkins R. Yogurt and other fermented foods as sources of health- promoting bacteria. Nutr Rev. 2018 Dec 1;76(Suppl 1):4-15.

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• Aryana KJ, Olson DW. A 100-Year Review: Yogurt and other cultured dairy products. J Dairy Sci. 2017 Dec;100(12):9987-10013.

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• Swallow DM. Genetics of lactase persistence and lactose intolerance. Annu Rev Genet. 2003;37:197-219. doi: 10.1146/annurev.genet.37.110801.143820. PMID: 14616060.

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• https://www.mayoclinic.org/diseases-conditions/lactose-intolerance/symptoms-causes/syc-20374232

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In the introductory and conclusion sections of my presentation, I used several images which I found on Google. These images were created by unknown authors and licensed under CC-BY