While fruits are generally considered to be healthy, their health benefits are dependent on how they are ripened. The best method is to allow them to ripen naturally on the plant itself. As fruits mature, they undergo a series of physical and biochemical changes that are irreversible and ultimately lead to senescence. This process involves the fruit becoming soft, changing color, developing a characteristic aroma and flavor, and an increase in sugar levels and a decrease in acid content. Ripening is influenced by several factors including temperature and relative humidity.
However, in many cases, it is not feasible to allow fruits to ripen naturally, particularly when they need to be transported over long distances. In such cases, farmers often harvest fruits before they are fully ripe to prevent spoilage during transportation. These fruits are then artificially ripened using specific chemicals at their destination.
Most fruits produce a gaseous compound known as ethylene, which triggers the ripening process. The level of ethylene in under-ripe fruit is typically low, but as the fruit develops, it produces larger quantities of the chemical, which speeds up the ripening process. Recent studies have revealed that ethylene plays a key role in regulating the expression of several genes involved in fruit ripening. These genes convert complex polysaccharides into simple sugars and make the skin of the fruit soft. In artificial ripening, this process is mimicked using chemicals.
The most used chemical for artificial ripening is ethephon (2-chloroethyl phosphonic acid), which penetrates the fruit and decomposes ethylene. Another compound used is calcium carbide, which produces acetylene, an analogue of ethylene. However, calcium carbide is associated with several issues, including being explosive and breaking down the organic composition of vitamins and other micronutrients. Additionally, it only changes the skin color, leaving the fruit raw inside. Furthermore, industrial-grade calcium carbide is often contaminated with trace amounts of arsenic and phosphorus, which are toxic chemicals.
Symptoms of arsenic and phosphorus poisoning can include vomiting, diarrhea with or without blood, weakness, burning sensation in the chest and abdomen, thirst, difficulty swallowing, burning of the eyes, permanent eye damage, and ulcers on the skin, mouth, nose, and throat. Other symptoms may include throat sores, cough, wheezing, and shortness of breath. Consumption of artificially ripened mangoes, for instance, can upset the stomach and damage the mucosal tissue in the stomach, disrupting intestinal function. Prolonged exposure to the chemicals can also cause peptic ulcers.
Studies have revealed that calcium carbide can also affect the neurological system by inducing prolonged hypoxia. Symptoms of this can include headache, dizziness, high sleepiness, memory loss, cerebral oedema, numbness in the legs and hands, general weakness, cold and damp skin, low blood pressure, and seizures. Pregnant women need to be especially careful and avoid consuming fruits and vegetables that have been artificially ripened with calcium carbide.
In Nepal, the use of calcium carbide to ripen fruits is prohibited under the Food Act of 1967. This act is enforced by the Department of Food Technology and Quality Control (DFTQC), which is responsible for ensuring that food products meet the required standards and are safe for consumption. Fruits ripened with artificial chemical ripening agent are considered as adulterated foods and can be charged from Rs 50,000 to Rs 500,000- or one-year imprisonment or both. Despite the ban, the use of calcium carbide to ripen fruits continues to be prevalent in Nepal, particularly in small-scale fruit markets.
Consumers can avoid consuming fruits that have been artificially ripened by looking for signs of ripeness. For example, a ripe mango will have a sweet aroma, a bright yellow or orange skin, and will yield slightly to gentle pressure. On the other hand, an unripe mango will be firm and green. Additionally, consumers can buy fruits from reliable sources, such as established supermarkets, and ask the seller about the origin and ripening process of the fruits.
In conclusion, while fruits are generally considered to be healthy and nutritious, the method of ripening can significantly affect their quality and safety for consumption. Artificial ripening using chemicals such as calcium carbide can have detrimental effects on human health, including poisoning and neurological damage. Consumers should be aware of the signs of ripeness and avoid consuming fruits that have been artificially ripened.