Pesticides play a positive role in pest and fungi control, weed removal, etc. However, long term and/or overdose usage of pesticide could lead to contamination of the food products. As being a large agricultural country, pesticide residues contamination on agricultural products has always been an eye-catching food safety issue. Therefore, aside from the degradation of pesticide residues in soil, we also developed a rapid detection method of pesticide residues on fruits and vegetables by using color change reactions, combined with a color comparison App we developed, to analyze the seriousness of pesticide residue contamination.
Detection principle: cholinesterase catalytic indophenol acetate (red) hydrolyzed into acetic acid and indophenol (blue), organic phosphorus and carbamate pesticides had inhibitory effects on cholinesterase, make the process of catalysis, hydrolysis, color change, which can have high doses of the organophosphate or carbamate pesticides in samples of the judge there.
Judgment standard: We used cholinesterase to soak filter paper overnight, made enzyme tablets, and made several different concentrations of organophosphorus pesticides standard samples as test samples. Through experiments, we recorded the color of each enzyme reaction. To this end, we have developed a APP, which can be tested according to the color of the enzyme chip.
This is the home page of APP. Users can choose the corresponding color according to the result of the pesticide residue test by click the color circle, which takes to the resultpage.
Test results are shown here and suggestions on how to detoxify are given. In addition, users can share their test results on WeChat, QQ or Facebook by clicking on the sharing icon in the lower right corner.
Users can also check relevant National standards on pesticide rules and regulations in China by returning to the homepage of APP. By clicking "national standard" button, a list of government rules and regulations, as well as reference are displayed.
In addition, there is a social network section on the App homepage. By clicking on the "micro community", a list of features is displayed, such as "Hot spot", "latest news of food security" ‘Feature section’, etc. Each section features extensive information on pesticide residues, food safety, how to maintain healthy lifestyle, etc. For instance, ‘hot spot’ contains the latest release and discussions on food safety and expertise opinions. "latest news of food security" contains pesticide and food safety related news articles.
In the process of developing our App, we conducted a survey (refer to outreach) on the awareness of harmfulness of pesticide residues on food products, people’s opinion on GMOs, as well as the interest in using the detection product and App, to find out how potential users respond to our project. The survey was conducted with residents and visitors in three large farm markets in Shenzhen, Jieyang and Guangzhou. In total 1000 survey forms were handled out, male to female ratio was carefully maintained, and wider age groups were selected. In the end, 525 copies of effective filling survey forms were returned. The proportion of male to female respondents was 4:6, most of which are between 20-50 years old. More than half (52%) of the respondents have a bachelor's degree or above.
In the survey, more than half (51%) of the respondents were very aware of the harmfulness of pesticide residues thanks to the widespread media coverage on poisoning incidents. In addition, about half of the respondents considered that pesticide residual limit standards are not very enough to be comprehended, despite the fact that they were aware of the existence of relevant policies, but lack of convenient channels to inquiry.
Therefore, we identified the needs of strengthening propaganda by adding a column of "National standard" of pesticide residues on the App. We believe this approach not only serves as a channel for consumers to inquire about relevant policies on pesticide usages and standards, but also helps promoting novel degradation technologies of pesticide residues. Furthermore, the survey results showed that most people do not use pesticides quick test card, however around 47% felt it is necessary to test pesticide residues on food products before consumption. A good proportion of respondents are willing to try (45%) or will consider trying (47%) if the detection method is simple to handle, and sufficient & professional information is provided.
As far as genetic modification is concerned, most people (55%) accepted the idea of applying genetic modification methods for pesticide residual degradation, as long as the technology is used for environmental protection and health promotion purpose. We also noticed, however, that the application of biotechnology in daily life is still very limited. By developing the App, we could on one hand help ensuring food safety related to pesticide residue issues, one the other hand promote the application and popularization of the genetic modification technology to ordinary consumers.
Conclusion remark: Given the limited of time and resources, we were only able to obtain a small amount of experimental data for App development. Thus the colour comparing feature of the proposed App is very limited. The App is still on the offline status, and needs extensive improvements on functions before can be put online. In the future, we also plan to develop biosensors that are able to detect color directly and use together with our App to improve detection efficency, sensitvity, result accuracy and customer experience.
