Can persimmons be poisoned when eaten with seafood? Is persimmon white cream a preservative? 7 "rumors" about persimmons, one article to make it clear

(Image from the Internet)

Autumn is the taste of persimmons, which have been given a beautiful meaning since ancient times, and are also known as "sacred products in fruit".

According to legend, during the ancient Song Dynasty, people would put a kind of lishi called "Pepsi Ji" on the table during the New Year, that is, persimmons, oranges and cypress branches were all put on the same plate, the cypress branches were broken first, and then the persimmons and oranges were broken in turn. This is "cypress persimmon orange", which means "Pepsi Ji".

Nowadays, persimmons are often pinned on people's good expectations, such as "persimmons are ruyi", "good persimmons into pairs" and so on. However, when it comes to eating persimmons, everyone has different opinions, and some people even dare not eat persimmons. What about persimmons? Let's turn over the case for persimmons!

Why are persimmons astringent,

Some sweet?

Some persimmons bite sweetly, while others make people's tongues numb. The ingredient that causes this difference in taste is the tannins, also called tannic acid, contained in persimmons.

Tannins in food feel astringent when they come into contact with the tongue because tannins clump proteins in saliva, increasing surface friction. The lower the ripeness of the fruit, the higher the tannin content and the more astringent it will taste. [1]

Among common fruits, persimmons are second to none in tannins.

However, the astringency of persimmons is also related to the variety, which is divided into four categories: sweet persimmon, incomplete sweet persimmon, astringent persimmon, and incomplete astringent persimmon, and the soluble tannin content of the latter two is significantly higher than that of the first two.

Persimmons can reach more than 4% tannin at the highest and around 0.5% at the lowest. [2] Sweet and incomplete sweet persimmons can be naturally deastringent on the tree as maturity increases, while astringent and incomplete persimmons must be artificially deastringent after picking. [3] After deastringency, the astringency becomes lower and the sweetness is obvious.

How can astringent persimmons change

"Not astringent"?

Most sweet persimmons are available on the market, and even astringent persimmons are manually deastringent and then sold. However, if you buy persimmons at a personal stall, it is likely to be persimmons that have not been deastringent, and the more astringent the taste, the higher the tannin content, and this astringent taste is really difficult to swallow. How can this be done?

There are many ways to deastringent persimmons on their own.

1. Seal with ripe fruits: some ripe fruits will release ethylene, such as bananas. Because ethylene molecules are small and gas at room temperature, it is easy to diffuse to other tissues and the external environment. [4] Ethylene can promote persimmons to produce acetaldehyde, and in the hypoxic or anaerobic state, it can also activate alcohol dehydrogenase, produce a large amount of acetaldehyde, promote the condensation of soluble low molecular tannins with astringency, and form insoluble polymer condensed tannins, so that the astringency disappears and plays a role in deastringency. [5]

2. Soaking in warm water: Soak persimmons in warm water at 40°C, heat continuously, and maintain them for 16-18 hours [6], which will produce more acetaldehyde and shorten the deastringency time. However, if the temperature is too high and exceeds 60°C, astringency may occur. [5] After deastringency, persimmons are soft, so eat them as soon as possible.

3. Cold water deastringency: putting persimmons in cold water for anaerobic respiration can produce ethanol and acetone, and then convert to acetaldehyde and deastringency. This method of astringency takes a long time, but it is easier to operate and has a crisper taste than warm water. [5]

4. Frozen persimmons thaw and astringency: The bought persimmons can be placed in the refrigerator freezer to freeze slowly, and studies have found that slowly frozen persimmons can be deastringent after thawing, while quick-frozen persimmons cannot be astringent after thawing. This may be because slow freezing destroys cell walls and cell membranes to produce large amounts of water-soluble pectin and sugars, making the tannins gelatinous and the astringency disappearing. [3]

In addition, northern folk often put more astringent persimmons on the outdoor windowsill, and after a long time, the persimmons will naturally become soft and the astringency will become lighter.

What are the nutrients of persimmons?

Persimmons have been cultivated on the mainland for more than 3,000 years, which is enough to show how much people love persimmons. This is not only because the deastringent persimmon is delicious, but also because it is highly nutritious.

1. Vitamin C: 100 grams of persimmons contain 30 mg of vitamin C [7], which is similar to the vitamin C content of oranges. The weight of a large persimmon is generally more than 200 grams, and eating one can meet more than 60% of the vitamin C needs of the average adult throughout the day.

2. β-carotene: The content of β-carotene in persimmons is 2210 micrograms/100 grams [8], which is similar to the content of β-carotene in carrots (the content of carrots is 2653 micrograms/100 grams [7]). β-carotene can be converted to vitamin A in the body, which is good for eye health.

3. Dietary fiber: The dietary fiber in persimmons is mainly pectin, accounting for about 5%-8%, [2] belongs to a kind of water-soluble dietary fiber, which can absorb water and expand, and is fermented and utilized by microorganisms in the large intestine, promotes gastrointestinal peristalsis, prevents constipation, and is beneficial to intestinal health. Pectin also has the effect of lowering blood lipids, preventing arteriosclerosis, and preventing coronary heart disease.

4. Flavonoids: persimmons are rich in flavonoids, which have antioxidant, anti-tumor, free radical scavenging, anti-aging and other effects.

Gossip about persimmons

1. Eating persimmons on an empty stomach with long stones?

It cannot be generalized.

Eating persimmons with a high tannin content on an empty stomach will increase the risk of stomach persimmon stones.

Tannins can form indigestible complexes with dietary proteins and sugars in the digestive tract, reducing nutritional value and affecting the role of gastric enzymes. It will also be mixed with protein, pectin, etc. under the action of stomach acid to form gastric persimmon stones, resulting in stomach discomfort. [9]

If you eat overripe sweet persimmons or deastringent persimmons on an empty stomach, don't worry too much. But for small children and people with poor gastrointestinal function, it is best not to eat persimmons on an empty stomach.

2. Can't persimmons be eaten with yogurt?

The reason for such rumors is also because of the tannin component in persimmons. It is thought that the tannins in persimmons react with the proteins in yogurt to produce precipitates, leading to stones.

In fact, as long as it is a persimmon with low tannin content, it can be matched with confidence. Not to mention yogurt, even milk, chicken, beef, etc.

3. Can't persimmons be eaten with seafood?

Rumors have it that persimmons and seafood can cause poisoning, in addition to tannins binding to protein, but also because vitamin C in persimmons will convert the pentavalent arsenic in seafood into toxic trivalent arsenic, producing arsenic.

In fact, it is not reliable to talk about toxicity regardless of dose. If you want to eat poisoning through the combination of persimmon + seafood, then you need to eat about 100 kilograms of seafood, and normal people's stomachs really can't do it.

4. Can't eat persimmons for anemia?

Persimmons contain tannins, which, under the action of gastric acid, will redissolve the polymerized persimmon tannins, forming larger insoluble substances with macromolecular sugars and proteins, affecting the absorption of iron, calcium, etc. and the effective use of vitamin A and vitamin B12. [3]

Therefore, anemic friends are worried that eating persimmons will be more anemic. In fact, don't worry too much, first of all, you can choose sweet persimmons with low tannin content, and secondly, you can add iron-rich foods to your diet, such as animal liver, lean meat, clams, etc.

5. Can't eat persimmons for weight loss?

Most of the friends who are in the weight loss period are more concerned about calorie intake, and persimmons are higher in calories than apples, grapes, peaches, pears, oranges, etc. that we often eat. Therefore, many weight loss friends are discouraged by persimmons.

In fact, even if you are losing weight, you can eat persimmons, as long as the calories consumed > the calories ingested are beneficial to weight loss. The calorie of persimmons is 74 kcal/100 grams, which is about the same as a pomegranate. [7] According to the recommendations of the "Dietary Guidelines for Chinese Residents", fruit intake should be controlled at 200-350 grams per day, a large fist persimmon, about 100 grams, and a smaller fire crystal persimmon is only about 100 grams.

However, sweet persimmon cakes are high in calories, about 100 grams for 2 persimmon cakes, and up to 255 kcal. [7] Higher in calories than a bowl of rice, eating more will really gain weight.

6. Can't you eat persimmons for diabetes?

The astringent persimmon tastes sweet, but diabetics dare not eat it, for fear that eating it will raise blood sugar.

The glycemic index GI of persimmons is 61,[10] although it belongs to medium GI food, but to know the size of the impact of a certain food on blood sugar after consumption, you can not only look at GI, but also look at the glycemic load GL, GL<10 is a hypoglycemic load.

GL = food GI× the carbohydrate content available in that food (g)/100

The average carbohydrate in persimmons is 15 g/100 g [10], and if you eat only 100 g of persimmons, the calculated GL is 9. However, this is also close to the upper limit of the hypoglycemic load value, you still have to eat as little as possible, it is recommended to choose smaller persimmons, such as only 50 grams.

7. Is the white frost on persimmon cakes a preservative?

Persimmon cakes are sweet, dried persimmons with a moisture content of 33.8%[7] or even lower.

The dried persimmon cake has a layer of white powder on the crust, which is not an artificially added preservative, but a precipitated frosting.

Because persimmon cakes have lower moisture content than fresh persimmons, the sugar content is high, which limits the reproduction of microorganisms, so the shelf life is longer, up to more than half a year.

Summary:

It's persimmon season, and it's soft and sweet not to be missed! It is recommended to buy sweet persimmons directly, which are convenient and delicious. The level of persimmon tannin content can be judged by simply peeling off the skin and licking it with your tongue. If it is very astringent, take it off and eat it yourself!

Finally, I wish everyone "persimmon success in their hearts"!

Bibliography:

[1] By Harold Markey [US]. Translated by Cai Chengzhi. Food & Cooking. Vegetables, fruits, spices, cereals. Beijing Fine Art Photography Press.2013.8

[2] CHEN Pei,LI Ping,HAO Yanbin,QI Jianxun,DAI Shengjie,WANG Canlei,LENG Ping. Changes of soluble pectin and tannin content during ripening of persimmon fruit[J].Journal of China Agricultural University,2012,17(01):88-92.)

[3] ZHANG Baoshan,WU Xiaohong,CHEN Jinping. Journal of Shaanxi Normal University(Natural Science Edition),2008(01):99-105.)

[4]. Research progress on tannin changes during persimmon fruit development and drying[C]//.Proceedings of the 3rd National Symposium on Dried Fruit Production and Scientific Research.,2003:286-289.

[5] Chai Xiong, Jiang Xibing, Gong Bangchu. Research progress on astringency and storage methods of persimmon fruit[J].Hubei Agricultural Sciences,2012,51(07):1297-1302.DOI:10.14088/j.cnki.issn0439-8114.2012.07.053.

[6] Liu Tao,Zhu Wei,Li Chunmei. Current situation and countermeasures of persimmon processing industry in mainland China[J].Science and Technology of Food Industry,2016,37(24):369-375.DOI:10.13386/j.issn1002-0306.2016.24.064.

[7] Yang Yuexin. Chinese Food Composition Table, 6th Edition, Vol. 1[M].Peking University Medical Press, 2018

[8] LIU Tao,SUN Rongrong,ZHAO Chunping,LI Chunmei. Contribution of different components in persimmon fruit to antioxidant activity and its synergistic/non-synergistic effect[J].Food Science and Technology,2015,40(01):63-67.DOI:10.13684/j.cnki.spkj.2015.01.014.

[9] ZHAO Beita,LIU Linwei,LI Xuan,WANG Xiaoyong. Study on flocculation characteristics of persimmon tannin in simulated gastric juice[J].Northwest China Journal of Agricultural Sciences,2014,23(01):177-182.)

[10] Glycemic index http://www.glycemicindex.com/foodSearch.php at the University of Sydney

Author| Xue QingxinMember of Chinese Nutrition Society Registered Dietitian Registered Nutrition Technician Health Manager Public Dietitian Review | Song Shuang Associate Researcher, Institute of Nutrition and Health, Chinese Center for Disease Control and Prevention

(Popular Science China)