chemistry of yogurt formation

Yogurt is not new to me. We used to make yogurt from buffalo milk at home in Nepal on regular basis. My mom and dad don't make it anymore because of the lack of milk (no more buffalo). I guess, in Nepal, everyone (at least one in a family) knows how to make yogurt from milk.

We used to make yogurt in following way:

1. Boil milk and bring it to little bit lower temperature (40-50 deg C, my guess, never measured though).
2. Put the milk in a theki (wooden container). After ~2 days yogurt is ready. 

The process looks simple and easy. The good bacteria in milk convert milk to yogurt. During summer months the process is faster and the yogurt is bit sour. In contrast to this, during winter months the process is slower. That's why we used to keep the "theki" close to the chulo (oven) in kitchen.

Even though my parents are not making yogurt in Nepal, I have been making it here in the USA. We buy milk from Walmart/Safeway, boil it and bring it to some lower temperature (~50 deg C, have never checked though) and put in a container. This container contains little bit of yogurt as precursor material. The container is kept in oven area for ~24 hrs by then the yogurt is ready. Different flavoring materials, including sugar, can be added  depending on your taste.

Here is a video that explains the chemistry of yogurt formation.

Milk is liquid that contains many nutritional materials including proteins and carbohydrates. On the other hand yogurt is gel like semi-solid. It has different texture and taste than milk. 

When some "good" bacteria (you can Google the name of bacteria)  convert one of the carbohydrates in milk called "lactose" into "lactic acid", it brings the pH from neutral (milk) to acidic (yogurt). This change in pH brings another major change. At lower pH, casein (one of the major proteins in milk) becomes insoluble. This is why the yogurt is thick. The casein is soluble in milk in the form of micro micelles.
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This video was submitted to "ACS Everyday Chemistry Contest 2013" but didn't reach to the top. Winner will be announced on Monday next week (26th) on C&EN. This first attempt has encouraged me to make more videos explaining science of our everyday life. 

केमिकल बोण्ड बनेको/भत्केको प्रत्यक्ष्य हेर्न पाइने भो।

अमेरिकाको बर्कलि स्थित उर्जा विभागको (Department of Energy) प्रयोगसालाका बैज्ञानिकहरुले रासायनिक प्रतिक्रिया हुन भन्दा अगाडी र भै सके पछिको केमिकल बोण्ड (Chemical Bond) हेर्न मिल्ने टेक्निक बिकास गरेका छन। 

नौ दस क्लास देखि जोड्ने हो भने अहिले दुइ दसक हुन लाग्यो केमिस्ट्री पढेको र पढाएको।  केमिस्ट्री भन्दा बित्तिकै रिएक्सन (reaction) को कुरो आउछ. अहि रिएक्सनले पुराना चिज भात्किन्छन र नया चिज बनछन। चिज भन्नाले मोलेक्युल वा कम्पाउण्ड। त्यो प्रक्रियामा पुराना बोण्ड बन्छन र नया बोण्ड बनछन। उदाहरणको लागि, हाइड्रोजन र अक्सिजन मिलेर पानी बन्छ। 

2H-H + O-O >>>>2H2O

यो रिएक्सनमा हाइड्रोजन हैड्रोजन बिचको बोण्ड भत्किन पर्छ, तेस्तै अक्सिजन अक्सिजन बिचको बोण्ड पनि भत्किन पर्छ। अनि हाइड्रोजन र अक्सिजन बीच नया बोण्ड बन्नु पर्छ। 

अहिले सम्म पढेको/बुजेको भनेको यस्तो हुन्छ भन्ने मात्रै हो। विभिन्न सैधान्तिक ग्यान र सिदान्त हरुको माद्यम बाट बोण्ड यस्तो हुन्छा उस्तो हुन्छा भनेर बुझियो। आखाले देखेको हैन केरे। तर नया प्रविधिको विकासले गर्दा त्यो सम्भब भएको छ। चर्चित र प्रतिष्ठित जर्नल साइन्समा भर्खर प्रकासित लेख अनुसार मोलिकिउलहरु बिचको बोण्ड देख्न सकिञ्छ। 

माथिको चित्रमा हेर्नुस। तीनवटा बेन्जिन रिङ्ग मिलेर बनेको कम्पाउण्ड हो यो। दाया नया प्रविधिले (AFM) देखेको चित्र हो भने बाया भाग हामीले पहिले देखि भन्दै आएको वा पढ्दै आएको चित्र हो। अचम्मको कुरो के छ भने अहिले सम्म यस्तै हुन्छ भनेर पढेको कुरो ठ्याक्कै त्यस्तै नै रैछ। AFM ले खिचेको आकृति दुरुस्तै छैन त? तीनवटा बेन्जिन रिङ्ग अलि चहकिलो सेतो रंगले घेरेको छ। त्यस्तै दुइ वटा रिङ्ग लाई जोड्ने बोण्ड पनि देखिन्छ नि। सेतो सेतो। मेरो बिचारमा त्यो जहा जहा इलेक्ट्रोन छ त्यहा सेतो देखिएको होला। 

अब  चित्र हेरम फ़ेरि। माथिको कम्पाउण्डलाइ ततायो भने  केहि पुराना बोण्ड भात्किन्छन र नया बोण्ड बनछन। 

यसमा पनि बाया तिरको हामीले अहिले सम्म बनाउदै आएको चित्र भयो भने दाया तिरको AFM ले खिचेको आक्रिति। उस्तै छ नि है। मलाइ त  क्या  मज्जा लाग्यो यो नया खोज। कुनै  कल्पनामा वा अप्रतक्ष्य तरिकाले बुज्न नपर्ने भयो। कुनै कम्पाउण्ड्को structure प्रत्यक्ष्य हेर्न पाइने भयो। 

यी  सार्है साना हुने बोण्ड, मोलिक्युल, कम्पाउण्ड हेर्नलाइ बैज्ञानिकहरुले non-contact atomic force microscope (nc-AFM) मेसिन प्रयोग गरेका थिए। यी माथिका कम्पाउण्ड  कति सानो छ भन्ने बुज्न खोजम है  त। 

१. एउटा बेन्जिनमा छ वटा कार्बन र छ वटै हाइड्रोजन हुञ्छन। र एउटा बेन्जिन रिङ्ग लगभग ३-५ A (angstrom) जतिको छ माथिका चित्रमा। 

२. हाम्रो कपालको रौ लगभग दस लाख angstrom हुञ्छ। भनेको मतलब, कपालको रौ लाइ दसौ लाख सानो पार्दा बल्ल बेन्जिन रिङ्ग जत्रो हुञ्छ। 

साइन्स प्रकासित यो अनुसन्धान पुरै पड्न यो लिंक किलिक गर्नुस। पुरै पढ्न मिलेन भन्ने मलाइ सम्पर्क गरे  pdf पठाइदिन सक्छु। 

PNW-SETAC Conference

I participated in the 17th meeting of pacific north west chapter of society of environmental toxicology and chemistry(PNW-SETAC). It was from 27th -29th March 2008 at Oregon State University, Corvallis. It was a good opportunity to share my research findings to other folks there and learn something about what others are doing. Most of the talks and posters there were about toxicology and very few related to chemistry. I had poster presentation entitled "Particle phase polycyclic aromatic hydrocarbons in the atmosphere of Raipur, India".

more about the organizer: http://chapters.setac.org/pnwrc/

Awards were distributed to best oral and poster presenters for students in undergraduate, masters and PhD programs.

CHEMICAL CONGRESS IN Kathmandu!!!!!

Nepal Chemical Society "NCS" (oraganising committee) is going to organize a "CHEMICAL CONGRESS - 2008" during May 23-25, 2008 in Kathmandu. Such types of events are rarely held in Nepal. NCS is organizing this congress in association with Tribhuvan University and Kathmandu University. According to the official site of NCS, the congress will discuss the latest developments in chemical researches, technologies and chemical education with special emphasis on role of chemistry on the sustainable development and improvement of the quality of life in developing countries.

The congress will provide a wide forum for students and experts of the related field. And it aims to awake people about the relevance of chemistry in the national development. The eminent scientists from different countries have been invited to present plenary and keynote lectures.

The professional society of Nepalese chemists(NCS) is very sluggish. It publishes its journal(Journal of Nepal Chemical Society).

More about the congress at www.ncs.org.np.

Official email ID of NCS is nepchemsoc@yahoo.com

Major Breakthroughs in Chemistry in the year 2007

This article highlights some of the advances in chemistry in last year-2007. At the end of each year, time is to evaluate what scientists have done in their respective field. This article was published in Chemical and Engineering News.

You may also like chemistry blog: NepaChem

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Stu Borman

EACH YEAR the editors of C&EN select some of the most important research advances from among the stories we've reported throughout the year and highlight them in a year-end issue. This year we've selected about two dozen examples of chemistry-based research at its best.

© 2007 Science


Two Approaches Similar structures (one gold and one blue and red) of the membrane receptor β2AR were obtained by stabilizing the receptor with T4 lysozyme (gray, left) or an antibody fragment (gray, right). β2AR is only the second G-protein-coupled receptor ever analyzed structurally.

Of the various chemically related subdisciplines spanned by our selections, structural analysis stands out as the most prolific. Highlighted breakthroughs include structures of a G-protein-coupled receptor, a type of protein that's been nearly impossible to analyze; and a new technique that made it possible to obtain the first detailed structure of one of the largest biomolecular complexes in cells.

Other selections this year range from advances in neurochemistry and molecular biology to key discoveries in organic synthesis, nanotechnology, molecular imaging, and environmental chemistry. They include a possible cure for a mental retardation disorder, a surprising finding about a common mechanism of different types of antibiotics, the design and synthesis of one of the lowest-density crystals ever known, a source of power for nanoelectronic devices, and the real-time imaging of gene regulation in living cells.

Our choices are necessarily subjective and do not pretend to be comprehensive. Indeed, these studies represent only a few examples of the many ways in which chemistry-related research advances our society and improves people's lives each and every year.

Rett Syndrome Research Foundation


Rett Reversed Rett syndrome patients often have trouble walking. A study showed that Rett syndrome could be reversed in mice.

Complete Article here

Good Resource for Chemistry Teachers and Students

The link given here has great videos that teach you some fundamental aspects of chemistry. It is free. Its a World of Chemistry. It is appropriate for students taking high school or college chemistry, from introductory to advanced levels, and is easily applicable to different teaching approaches. It includes physics and Earth science components, and is also valuable for teachers seeking to review the subject matter. There is a collection of 26 videos on different topics related to chemistry.

http://www.learner.org/resources/series61.html?pop=yes&vodid=799734&pid=800#

“The Many Faces of Chemistry”

American Chemical Society(ACS) is celebrating its 20th National Chemistry Week(NCW), October 21-27. According to ACS NCW is a community-based annual event that unites ACS local sections, businesses, schools, and individuals in communicating the importance of chemistry to our quality of life.

This is mainly focused to school children and undergraduate students to encourage them to be interested in chemistry and related field so that many faces will be seen in future. There are several contests,like posters, going on in several communities.

Participate in the local community based programs to celebrate NCW.

WelCome!

Welcome in US

Every year hundreds of Nepali students come to US for their further study. Among them at least ~80 are graduate students. This is my tentative figure. Nobody knows exact data, even the Government of Nepal. Very few undergraduates get scholarship/free ship and most of them don't get that opportunity. Only getting VISA is great for their departure to the so called dreamland of many people. Actually this is a dreamland. Life is very hard without funding. A very handful students get funding from home back in Nepal otherwise others do hard work to make money for their living, tuition fee and others. Ok, lets leave this matter here. I will write about this in depth later on.

And welcome to graduate students!

All graduate students get either teaching assistantship(~95% at the beginning) or research assistantship which includes fee waive and stipend. They don't need to worry about economic problems. You can have American standard life (with your family). Some are even able to save some money from the stipend- thats great.

My friend Nabin has written on his blog that approximately there are 25 new comers in physics. And in chemistry about 30. I have talked to some of them to make approximation. How many in mathematics? Some body from the same subject can tell. Some are from geology, agriculture & veterinary, engineering etc. This number is huge number from a country like Nepal. We have only Tribhuvan University to produce Masters in almost all science streams. In case of chemistry intake every year is 90. This year ~30 came to US and others in other countries for M.S or PhD. So about 40-50% go abroad every year.

You have got new life in a sense and it is challenging as well. Any you made it. Congratulations! to all of you and welcome once again. I wish all the best to everyone in future.

Chemists! don't worry about Job

During my Bachelor's degree third year I had very hard time to choose my major. I had three options, Botany, Zoology and chemistry. I was equally interested to botany and zoology because I had thought that these subjects could bring me closer to community and nature than others. But for us(at least me, how abt you?), our interests is not the only one factor that decides your career. We look for availability of job also. Thats why I decided chemistry as specialized subject in the third year. The time was critical because you couldn't get admission in the subject other than your specialized one in Tribhuvan University. I decided chemistry as my major because I thought "I can earn for my living by tutoring private students." This is still true in Kathmandu. You can get more tutoring job with chemistry than with botany. I know most of the students feel chemistry is hard subject. Actually that was my good decision and I have no frustration after it. In my masters degree, I did very good. Now I am enjoying this area, though I have shifted little bit from pure chemistry to analytical-environmental chemistry.I can't guaranty that you can get good job in Nepal, but in USA a PhD chemistry graduate can earn $90000 per annum in average. Recently one article published in SCIENCE reveals that chemists have a broad, and broadening, range of career options to choose from, both in and out of the lab. This doesn't only include lab oriented works but also it explores 'not traditional roles'. Even with the exponential growth in the life science arena, chemists are central to the biotech and life science industries. Life science companies are crying out for postgraduate chemists.

According to the news report, Sigma-Aldrich which is a leading life science and high tech company hires about 45% chemists to 55% biologists at PhD level.

Non traditional chemists include all the science companies-chemical companies, biotech companies, pharmaceutical companies-but also law firms, companies involved in public policy, and companies involved in manufacturing or information technology.

Some of the chemistry areas in which you can find highly paid job easily are biochemistry, medicinal chemistry, analytical chemistry, combinatorial chemistry, synthetic organic chemistry etc.
Here are some links to some big organizations and companies. You can find more there.

Agilent www.agilent.com
American Chemical Society www.chemistry.org
Balbes Consultants www.balbes.com
Genentech www.gene.com
Royal Society of Chemistry www.rsc.org
Sigma-Aldrich www.sigmaaldrich.com