In daily life, yogurt is often used as a flavor drink because of its better taste, easier nutritional absorption and better regulation of human intestinal bacteria situation. After fermentation, the fatty acids in yogurt increase twice, making yogurt easily digest and absorb as well as improving the utilization of nutrients. Yogurt can be produced by using fresh milk as raw materials, adding a certain proportion of sucrose, sterilization and cooling, then appending lactobacillus with its culture as well as kinds of dairy products which allow product to taste sweet and smooth. In the fermentation process, lactobacillus can also produce human nutrition containing a variety of vitamins, such as vitamins. Its nutritional value is better than fresh milk and various protein powders.
However, according to our review of the relevant articles, we found that many by-products are produced during the process of yogurt fermentation, including a representative-- lactate. In the process of yogurt fermentation, the production of lactate will have a certain inhibitory effect on the growth of bacteria, but lactate is also an indispensable symbol of fermentation products. Therefore, the real-time monitor of lactate in the production of yogurt plays an important role that cannot be ignored, which can ensure the quality of yogurt fermentation.
Through referring to a large number of documents, we understood the actual production of yogurt in some cases, carefully thought and summed up the existing situation, and we provided our experimental plan. In order to make experiment more practical, we conducted company visiting and fermentation industry visiting.
1. Shanxi Zhen Dong Company Visiting
In order to understand the actual process of fermentation, we went to the company for observing the whole procedures.
Inside the enterprise, we went inside the factory and observed the whole process of food fermentation. During that time, we communicated with the employees about some problems we encountered in our experiment. In addition, we were trying to find out the ways to solve these problems in actual production. For example, how to prevent the material in industrial production from being polluted.
After a few days, we entered the Enterprise Quality Inspection Department, followed by the Quality Supervision Department staff to do a series of experiments, understanded the importance of quality for food company. In the process of quality inspection, we felt that the food quality testing is still time-consuming and laborious, but also might cause some pollution to the fermentation liquid. Moreover, we described our projects in details to their employees, and gained interests.Figure 1. Shanxi Zhen Dong Company
2. Fujian Normal University Beer Factory Visiting
In the process of reviewing articles, we also found that a certain amount of lactate is produced during the yeast fermentation, which has a strong inhibitory effect on the whole beer fermentation system.
We had cooperated with Fujian Normal University. Under the guidance of the students of Fujian Normal University, we had visited the beer factory inside the college to learn about the whole production line of beer production and the function of each step. In the course of the visiting, we retrieved a portion of the beer fermentation liquid to observe the experiment, and used chemical methods to detect the lactic acid content in the fermentation process.Figure 2. Fujian Normal University Beer Factory.
3. Northeastern University Yogurt Base
All of the members in our team visited the yogurt base of Northeastern University to learn the actual process of lactate fermentation.
With the development of technology, many people have small yogurt machine to make their homemade yogurt. But at the Northeastern University yogurt base, team members learned how to plant the fermentation tank for yogurt fermentation. During the visiting, with the introduction of teacher, we understand the operating principle of every step of the fermentation tank, as well as lactic acid in the production of real yogurt in the symbolic significance.Figure 3. Northeastern University Yogurt Base.
4. BGI (Beijing Genomics Institution) Visiting
In order to understand the principles of the experiment, and the actual situation of the gene industry, we came to the Beijing Genomics Institute to visit the field and have a deep communication with their staff.
At BGI, the staff introduced us to some of the existing businesses of the BGI, and we visited the gene pool. During the study of the project, we asked the staff of the specific research mechanism of gene sequencing, the existing gene sequencing technology and many other problems. The staff answered our questions. During the visit, we briefed them on our events and explained some of the problems we encountered in the experiment, the company's internal staff explained to us the possible causes of these problems, and expressed willingness to give us some help in the experiment.Figure 4. BGI (Beijing Genomics Institution)
1. Meetings with Professional Instructors
We invited four professors, professor Chen Ding, Ren Sheng, Teng Fei, Lijun Liu, for having discussions with our team members.
We presented our complete experimental project to the professors. During the presentation, professors asked us some questions about our experimental project, and we had an in-depth communication with them to better optimize our program. In the course of the discussion, the professors raised two questions: how long our testing system work can spend, and how many bacteria can be detected in the number of the threshold value. We did not discuss such issues in depth until then.
In view of the questions raised by the professors, we developed a series of discussions and finally completed the optimization of the experiment. In the final protocol, we used the optical fibers to detect the Fluorescence intensity. According to the data the conclusion can be obtained: when OD value is 0.6, reaction time is 5 minutes, fluorescence intensity of GFP can change with a high sensitivity, easier to operate and detect.Figure 5. Regular Meeting.
2. Practice in Information Institute of NEU
To better complete our project, we went to the information institution of Northeastern University to deeply understand how to use electrical components to achieve the conversion between photoelectric, fluorescent protein detection.
We discussed our project with professor Yanan Zhang and Riqing Lu coming from information institution. After presenting our idea of using fiber to detect fluorescence, professors affirmed our project and suggested improvements to our project from a professional point of view.
We originally decided to use Photoresistors to complete the entire experiment device, but in the process of communication with professors, we found that the light intensity range of Photoresistors is very wide, but fluorescent protein emitted by the light is very faint, it is difficult to achieve Photoresistors photoelectric conversion.
After adopting the professor's suggestion, we have made some changes in practical project, and fully perfected it. In the process of communication with students in the information institution, we fully understand the practical use and parameters of optical fiber, better understanding the various properties of optical fibers, optimizing our experimental plans. We also cooperated with the Information Institute, which provided us with theoretical guidance in the process of optical fiber conversion and helped us complete the whole process of the experiment.Figure 6. Information Institution in NEU.
3. Manager of NEU Yogurt Base Interview
After visiting the yogurt base, we interviewed the manager of the base-professor Jiang Liu and Zhenbo Cui. During the meeting with them, we learned that in the actual production process, workers often using acid-base titration method to detect the acidity of yogurt for reflecting the concentration of lactate. But this method is complicated and time-consuming in actual production. Therefore, we raised ideas of build a real time system to detect the concentration of lactate after in-depth discussion with professors. They with the professional perspective analyzed the feasibility of the whole project, felt that there is a strong display space.
In our actual experiment, we found that the expression level of lldPRD operon is relatively low, cannot express fluorescent protein GFP efficiently. According to the advice of professor, we introduced the E. coli QS system for amplifying the signal of the entire device. After adding QS system, the sensitivity of engineered E.coli has been improved.Figure 7. Manager of NEU Yogurt Base Interview.