You should know these facts about off-season vegetables!

The Analects of Confucius says: "Don't eat if it's not in season." This means that eating should be consistent with the season. For a long time, this view has also influenced the eating habits of the Chinese. In countless families, eating seasonal fruits and vegetables is considered a healthy lifestyle. Therefore, people's attitudes towards seasonal vegetables and off-season vegetables have always been subtle. Some people think that seasonal vegetables are in line with traditional habits and have high nutritional value; some people think that off-season vegetables enrich the variety of vegetables and make the table more flavorful. There has been endless debate about which of the two has higher nutritional value. So, what are the differences between "seasonal" and "off-season"?

Source: unsplash

1. What are off-season vegetables?

Seasonal vegetables follow the seasons and solar terms from sowing to germination, from maturity to sale. Off-season vegetables are more freely produced, breaking through time constraints and becoming hot fresh goods in the market. Generally speaking, off-season vegetables can be divided into three categories: off-season planting, emergency storage, and off-season cultivation.

The first type of off-season vegetables actually benefits from convenient transportation and developed logistics. The so-called off-season is just a geographical standard. A vegetable may be off-season in one place, but in season in another place. For example, when winter comes, the growth of vegetables in the north stagnates, while in the warm south, various vegetables can still be put on the market fresh under suitable conditions. Logistics transports these vegetables from the south to the north, and they become "off-season vegetables."

In winter, vegetables from the south are transported to the north, which is called "transporting vegetables from the south to the north".

Source: Xinhuanet

The second type is due to the advancement of preservation technology, which allows vegetables to be stored for a longer period of time. Vegetables in season in summer are preserved through preservation technology and enter the market in winter, which are also "off-season vegetables". Nowadays, preservation technology has ensured that many vegetables can be supplied all year round. Cabbage and potatoes, which are common guests on the tables of northerners in winter, have been stored before winter, and are actually off-season vegetables in a sense.

Source: Tencent News

The third is due to "greenhouse cultivation", which is the use of protective and semi-protective facilities to cultivate off-season vegetables. As a popular facility agriculture project in recent years, the greenhouse's powerful insulation and moisture retention function prevents vegetables from being affected by severe cold weather and can still grow normally. This is also a very common practice at present. In Shouguang, Shandong, the greenhouse intelligent management system already has extremely powerful functions, from automatic control of room temperature to automatic fertilization and watering, automatic lighting and ventilation, etc., to achieve visual control of greenhouses.

Source: Xinhuanet

2. Can out-of-season vegetables be eaten?

After having a certain understanding of the types of off-season vegetables, I believe that everyone's concerns about the first and second types of off-season vegetables can be basically dispelled, but there are still some concerns about vegetables grown in greenhouses. In life, there is no shortage of sayings such as "off-season vegetables are ripened by pesticides, hormones, etc. and cannot be eaten." So, is this really the case with the growth of off-season vegetables?

First, let's talk about pesticides. In fact, in the process of vegetable growth, it is normal to use pesticides to remove pathogens and pests, and the growth of seasonal vegetables also requires the help of pesticides. At present, the pesticides allowed by the state for use on fruits and vegetables have all undergone safety assessments, and the standardized and reasonable use of pesticides will not cause harm to the human body. For the problem of pesticide residues, the type and amount of pesticides used, as well as the length of degradation time (referring to the time from the last application of pesticides to the time they are put on the market for sale) are the determining factors. It is not the case that the "off-season" label is equivalent to pesticide residues.

Spraying pesticides

Source: unsplash

The second is "hormone ripening". Although many people in life think negatively of hormones, plant hormones (plant growth regulators) only work on plants, and can promote or inhibit plant growth and development, but have no effect on the human body. Currently, the plant hormones that are allowed to be widely used meet the requirements of non-toxicity and low toxicity. A small amount can play a role, and they will automatically degrade after use, with very low residues. Seasonal vegetables may also use plant hormones, so off-season vegetables can be eaten with confidence even if plant hormones are used normally.

Types of plant hormones include auxin, abscisic acid, cytokinin, ethylene, etc.

Source: webiolotech.com

3. Do off-season vegetables have higher nutritional value?

Are there differences in the taste and nutritional value of seasonal vegetables and off-season vegetables? The factors that determine the taste of vegetables are the sugar components (glucose, fructose, sucrose, etc.) and flavor components in vegetables. In addition to being related to the variety, the formation of these components is also closely related to light and temperature. High temperature, strong light, and large temperature difference between day and night are conducive to the accumulation of sugar components and flavor components in vegetables. Judging from the taste feedback of consumers, seasonal vegetables grown in the open field seem to taste better, such as tomatoes, cucumbers and other vegetables suitable for eating raw, as well as peppers, celery, etc., because they are in a more superior light and heat environment during their growth process.

Source: pixabay

The nutritional value of off-season vegetables is not compromised by their growth method, and some nutrients may even be better than seasonal vegetables. When the temperature during the growth process of vegetables is low, their own protection mechanism will prompt them to produce more vitamin C and phenolic substances. Due to the limitations of natural conditions, although there are artificial adjustment methods, the temperature during their growth process is generally lower than that of seasonal vegetables, and some are in a state of low temperature stress. Therefore, compared with seasonal open-field vegetables, the content of vitamin C and phenolic substances in greenhouse vegetables is not necessarily lower, and may even be higher.

Source: unsplash

In short, the emergence of off-season vegetables has broken the habit of people eating vegetables in season. The development of transportation and the advancement of preservation technology have brought people so-called off-season vegetables from other regions. Greenhouses, a new type of planting technology, provide suitable light, temperature, water and soil for the growth of vegetables. In seasons when supplies are relatively scarce, the emergence of off-season vegetables is a good thing, which not only enriches people's tables, but also provides more sources of nutrition.