Spring sleepiness brings refreshing "artifact" coffee, green tea, which has a high caffeine content.

When it comes to spring, in the afternoon, as the temperature rises, many office workers feel lazy and listless. In order to combat the "spring sleepiness", we have also come up with various refreshing ways. Our reporter did a survey and found that drinking coffee, especially instant coffee, is the most common refreshing method, and in the opinion of many people, the refreshing effect of instant coffee is quite good. But is instant coffee really that effective?

As the first of the three major drinks in the world, coffee has long come into our lives and is welcomed by more and more people. As a more convenient coffee drink, instant coffee has a history of more than 100 years. In the coffee area of the supermarket, the reporter calculated that there were no less than 20 varieties of instant coffee sold here. With a full range of tastes, affordable prices and simple brewing, instant coffee has become a necessity for many people.

College student Xiao Liu: because you have to drink some coffee when you have to review during the exam, you can be more sober.

Reporter: how is the refreshing effect of coffee?

College student Xiao Liu: the effect is not bad.

Ms Li: I think instant coffee should be refreshing.

Instant coffee has a refreshing effect, mainly because it contains caffeine, caffeine can excite nerves, thus dispelling fatigue. Although many people are convinced of the anti-fatigue effect of instant coffee, whether instant coffee can be regarded as a refreshing artifact needs to be proved by experiments. Because instant coffee generally adds a variety of additives, in order to detect the caffeine content in pure coffee, the reporter specially bought fresh coffee beans and brought these samples to Xi'an Nutrition Society.

Li Qizhang, member of the Public dietitian Branch of Xi'an Nutrition Society: our experiment today is to sublimate the caffeine in the sample by heating and crystallize it on the filter paper, so that it is deposited on the filter paper. The caffeine content in the sample can be determined by judging the amount of caffeine on the filter paper.

The experimenter first grinded the coffee beans into powder, took 5 grams of samples from coffee powder and instant coffee and put them into evaporation dishes, and then added 1.75 grams of calcium oxide to dry and dehumidify. After stirring well, heat the sample until the color is yellowish. After the sample is cooled, the experimenter puts the filter paper with many small holes on the sample, places the funnel on the filter paper, and continues to heat it. The experimenter told reporters that if the sample contains caffeine, white hairy crystals will appear on the paper holes when the sample is heated. A close examination of the filter paper on the two coffee samples shows that there are a few caffeine crystals on the filter paper covered with coffee bean powder, while there are few caffeine crystals on the filter paper covered with instant coffee.

Usually people patronize to drink coffee, I believe many people do not know how much caffeine there is in instant coffee. Through the experiment, we found that the caffeine content of instant coffee is very limited, so is there anything more refreshing than coffee?

Through the survey, the reporter found that nearly half of the respondents between the ages of 30 and 60 had the habit of drinking tea. Spring is the time for green tea to go on the market. Ziyang selenium-rich, Huangshan Maofeng and Xihu Longjing Tea green teas have all been on the market one after another in the past two days. So, in everyone's opinion, will green tea contain caffeine?

Interviewer: does green tea also contain caffeine?

Ms. Li, a citizen: there is usually no tea.

Reporter: which do you think is more refreshing, green tea or coffee?

Mr. Ma: green tea, please.

Whether green tea contains caffeine or not, we still prove it through experiments. The reporter will buy two different varieties of fresh green tea to Xi'an Nutrition Society, the experimenter will still use sublimation to extract the caffeine content of the two kinds of tea. After heating, the experimental results show that the surface of the filter paper covered with two pieces of tea is densely covered with caffeine crystals, which can be seen in the light. Compared with the caffeine precipitated from coffee beans and instant coffee, green tea contains much more caffeine.

Li Qizhang, member of the Public dietitian Branch of Xi'an Nutrition Society: through the experiment, we found that the caffeine content of the two kinds of tea we selected is about the same, and the caffeine content of coffee beans is higher than that of instant coffee. In our test samples, we found that the caffeine content in green tea is relatively high, while that in instant coffee is relatively low. If it is for refreshing purposes, then choosing green tea is better than coffee in this group of samples.

Li Qizhang told the reporter that the reason why coffee gives people a more refreshing effect is mainly because we usually add more coffee when making coffee, while making a cup of green tea requires only a little tea, so the refreshing effect of green tea seems to be a little weaker. So, what do you need to pay attention to when choosing instant coffee?

Li Qizhang, member of the Public dietitian Branch of Xi'an Nutrition Society: when we choose instant coffee, if we look at the list of ingredients to refresh ourselves, it will show the content of coffee. If there is no such content, we can take a look at the order of coffee in the list of ingredients. The order at the top of the order indicates that the content is higher.