March 27, 2020
March 19, 2020
Given the growing importance of organic farming, it is necessary to find out if the chemical composition of fresh produce grown organically differs from conventionally produced food. Dry matter content is one of the components that have been used to evaluate the differences. Since dry matter is an important indicator of quality, the difference in its levels can influence not only the nutritional value of fresh produce grown organically, but also final acceptance by consumers.
Organic farming is the method of growing crops and animals without the use of chemicals and genetically modified organisms. This holistic system of farming works with natural systems to enhance the capacity of soils to produce more plants. Soil fertility is built up and maintained by using manure, crop rotation, and intercropping. Pests, weeds, and diseases are controlled by using natural pesticides or natural enemies. Organic farming has several ecological benefits, as it does not pollute the environment like industrial agriculture does.
Some crops are more difficult to grow organically than others. In certain cases, yield can be 20% lower than from conventional farms. However, under natural stress and in small scale farms, organic agriculture can give higher yields than conventional farms.
Advocates of organic farming have long argued that the quality of vegetables and fruits produced organically are superior to those produced from conventional farms. Indeed, the quality and safety of organic food in terms of freshness, health benefits, nutritional value, or flavour are stated as reasons why 70% of consumers choose organic food.
One of the ways to measure the difference in organic and conventional fresh produce is to check their chemical composition. Dry matter content, proteins, sugars, minerals, and vitamins are some of the components that have been tested to measure this difference. Near Infra-Red (NIR) Spectroscopy was the technology that was used to measure several of the components that make up fruits and vegetables.
All studies agree that organic foods are safer, have less pesticide, and do not suffer from antibiotic resistance.
However, some of the earlier studies indicated that there was no difference in the nutritional content between organic and conventional food. There is, however, a growing consensus as more in-depth studies are conducted around the world: organic food is significantly more nutritious than conventional food.
Organic fruit and vegetables have a higher content of total soluble sugars, aromatic compounds, organic acids, vitamin B and C, phenolic compounds, phytonutrients such as antioxidants, and amino acids in organically grown fresh produce. Minerals can also be higher in some vegetables and fruits.
As a result, the overall dry matter (DM) content is also higher, since it is the sum total of the solids in a fruit minus its water content. This includes sugars, starch, cellulose, fats, proteins, vitamins, pigment, and inorganic minerals.
A few of the organic fresh produce have registered as much as 20% more dry matter content than conventional fruits and vegetables. However, not all fruit and vegetables show a consistently higher DM content. Apples, potatoes, and carrots are notable exceptions, and the dry matter content in them is similar in both kinds of cultivation. In some cases, like beetroots, the dry matter in the underground vegetable is less when they are organically grown than compared to conventional methods.
There can also be variations in the different compounds which do not correlate with changes in dry matter. For example, protein levels in organic potatoes are higher than in conventional potatoes, even though the dry matter content is similar. Moreover, levels of β carotene are higher in conventional produce, regardless of DM content.
Figure 1: There is a difference in the dry matter of organic and conventional fruits and vegetables, Liyue Guo. (Image credits: DOI: 10.1016/j.chnaes.2018.01.009)
Many possible reasons have been identified for the higher dry matter content in fresh organic produce.
One of the main reasons is that the use of fertilizers is accompanied by an increase in the absorption of water. In the presence of more water content, the dry matter percentage falls.
Another reason in the case of fruits is that they are harvested early in conventional farming. The maturity period is cut short for extending transport time, and the fruits are artificially ripened later using chemicals. This is in sharp contrast to organic farming, where fruits are plucked at a later mature stage and, therefore, accumulate enough dry matter.
Due to higher levels of DM, fresh produce grown organically can have many advantages:
Besides the method of farming, other factors—such as variety, climate, location, and soil type—can also have a great influence on the nutritional value of fresh produce.
Though only 1.4% of agricultural land is under organic farming worldwide, the demand for organic products is growing. There has been a 20% increase, globally, from 2016 to 2017. The increase in revenue was also in double digits. More information is needed about organic products. For example, regarding the differences in the composition between conventional and organic products, which are not the same across all species of fruits and vegetables. More research is also necessary to study changes in DM and their impact. Luckily there are enough precision instruments, such as the F-750 Produce Quality Meter by CID Bio-Science Inc, to assist scientists in tracking DM and other plant components and also help growers and suppliers.
Science Writer, CID Bio-Science
Ph.D. Ecology and Environmental Science, B.Sc Agriculture
Featured image credit - Zeyus Media
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