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Consumer alert : Ethylene for Ripening of Fruits

Chemical ripening is assuming endemic proportions

How safe are our fruits?
All Lose: Growers and consumers are both impacted by chemicals for ripening bananas.


INDIA is blessed with diverse agro-climatic conditions and produces a wide range of fruits and vegetables. It ranks second in fruit and vegetable production in the world, after China. As per the database published by National Horticulture Board, during 2016-17, India produced 92.85 million metric tonnes of fruits and 175 million metric tonnes of vegetables. The country ranks first in the production of banana, papaya and mango. Unfortunately, these three fruits are commercially ripened by traders with calcium carbide, which is illegal and against food safety regulations. 

Fruit-ripening poses a great health concern among the consumers. Although the natural ripened fruits (either ripening on the tree or off the tree) are good in taste and flavour, whole batches of fruits do not ripen uniformly. Moreover, it takes a longer time to complete the ripening process. The emergent market demand of ripened fruits cannot be fulfilled by natural ripening practices. Therefore, to regulate the supply chain in markets, hastening of the ripening process of fruits with the application of ethylene gas is a necessity during their commercial handling. This is a standard practice followed all over the world. 

Ripening is a dramatic event in the life of a fruit, in which structure and composition of unripe fruit is so altered that it becomes acceptable to eat. Ethylene, a gas at physiological temperature, is a natural plant hormone involved in fruit-ripening. The autocatalytic production of endogenous ethylene immediately triggers the ripening process in banana, mango, papaya etc. The fruits produce large amounts of ethylene once ripening is under way. 

Bananas, mango, papaya etc are commercially ripened with calcium carbide, popularly known as masala. Calcium carbide is usually kept in small paper packets in piles of bananas, papaya or inside the boxes or crates of mango fruits. The chemical comes in contact with moisture and gets hydrolysed, produces heat and acetylene gas which hasten the ripening process.  In the case of banana, the ripening starts within 24-48 hours, depending on ambient temperature. When the fruits yield to a slight finger pressure, they are kept under ice slabs for lowering the temperature and developing colour.

Mango and papaya are ripened the same way with calcium carbide, but these are not kept under ice slabs. The fruits so ripened are overly soft, non-uniform in ripening and have a short shelf life. In addition, it is dangerous to handle calcium carbide because of its explosive properties. The chemical is so reactive that it causes blisters if touched with wet hands. The low price of carbide results in its indiscriminate use in artificial ripening of fruits. 

The use of calcium carbide for the ripening of fruits is banned by Food Safety and Standard Regulations of the Food Safety and Standard Authority of India (FSSAI). Ethylene is a plant hormone, which acts physiologically and stimulates the ripening of fruits. It is known as the ripening hormone. No doubt, fruits contain natural ethylene, but its concentration is not enough to regulate the ripening. Therefore, fruits are required to be exposed to the desired level of ethylene for developing uniform ripening and acceptable quality. This technique is useful during the commercial handling of fruits. In this technique, the fruits are exposed to ethylene gas (100 ppm) in an airtight ripening chamber for 24-48 hours to induce ripening. The most important thing is the control of temperature and relative humidity inside the chamber, which should range between 16 -25 degrees and 90-95 per cent RH, depending upon the fruit. Ethylene gas is introduced inside the chamber with an ethylene generator.

Punjab Agricultural University has recommended the technology for ripening of banana fruits with ethylene gas under controlled conditions. Banana fruits harvested at the green mature stage can be successfully ripened in four days by exposing them to ethylene gas (100 ppm) for 24 hours in a ripening chamber maintained at 16-18 degrees and 90-95 per cent RH. The fruits attain uniform colour and excellent quality.  The technology can be used at wholesale markets. Though ethylene gas can promote ripening and colour changes, the quality of such artificially ripened fruit depends mostly on the maturity level of the fruit at the time of harvest. This technique provides a safe and effective method of ripening of fruit compared to the traditional technique of using calcium carbide.  The Food Safety and Standards- Second Amendment Regulation, 2016, under the FSSAI, has permitted the use of ethylene gas in the artificial ripening of fruits.

The Food and Drug Administration (FDA) has also sanctioned the use of ethylene gas to promote the ripening of fruits and vegetables under Regulations 120, 1016.  Farmers, traders and other stakeholders are enlightened about FSSAI regulations regarding harmful and safe ripening techniques during training programmes conducted by Punjab Agricultural University, Punjab Horticultural Postharvest Technology Centre, Punjab Mandi Board, Department of Horticulture and Krishi Vigyan Kendra etc. The pilot facility with 46 ethylene gas based ripening chambers of capacity of about 460 metric tonne has been established by Punjab Mandi Board at 12 fruit and vegetable markets of Punjab. In addition, about 825 metric tonne capacity of ripening chambers established by private entrepreneurs has also come up in Punjab with the financial assistance of National Horticulture Mission. However, keeping in view the volume of these fruits in mandis, more infrastructure is required to be established in Punjab to replace the harmful and banned method of ripening with calcium carbide.

Artificial fruit ripening

Fruits and vegetables are highly nutritious and form as key food commodity in the human consumption especially during summer season. As the summer season bids arrival in the valley, succulent fruit of varied climacteric fruits have surfaced the markets too early.
Many fruits are harvested in unripe conditions itself and are allowed to ripen by the natural release of ethylene, which is a ripening hormone in the fruit itself. But, these fruits like Mangoes, Bananas, Papayas, Chiku, Dates and Tomatoes are artificially ripened using artificial ripening agents.
Chemicals like calcium carbide, ethephon and oxytocin are purportedly being used in fruit and vegetable Mandis and farms for simulated ripening. While ripening using the ethylene gas does not seem to have any harmful effects up to certain limits, there are chemicals like Calcium Carbide which have significant ramifications for human health.
Menace of Masala and Carpet
Calcium Carbide (CaC2) popularly known as ‘Carpet’ is most frequently used for artificial ripening of fruits. When it comes in contact with moisture it produces an unsaturated hydrocarbon gas namely acetylene, which is analogous in nature to the natural ripening agent ethylene. It is the cheapest artificial ripening agent available, with mere Rs 100/kg sufficient enough to ripen over 100 dozen of raw mangoes.
It is a well known carcinogen, irrespective of quantity consumed; it is known to have harmful effects on the liver and other parts of the body as contains traces of arsenic and phosphorus hydride which produces numerous severe and chronic health effects.
Common symptoms of arsenic or phosphorus poisoning include vomiting, thirst, and weakness, burning sensation in the chest and abdomen, diarrhoea, irritation or burning of the eyes irritation in the mouth, nose and throat. Higher and prolonged exposure to the chemical could lead to peptic ulcer and build-up of fluids in the lungs.
Another chemical ethylene (C2H4, also known as Ethene or carbide gas) or ‘Masala’ by the suppliers is a gaseous organic compound a natural plant hormone, which assists in the process of ripening. Commercially, Ethylene is the most produced organic compound in the world and is used in many industrial applications.
While calcium carbide is banned, but FSSAI has clarified ambiguity regarding the use of ethylene in its Second Amendment Regulation, 2016 and included of use of Ethylene gas for ripening of fruits in low concentration of 10-100 ppm exogenously to trigger their ripening and declared it safe in the concentration varying from 0.001- 0.01% depending upon the crop, variety and maturity.
However, it is advised to the vendors to use it under controlled temperature and humidity levels besides monitoring the levels of carbon dioxide in ripening rooms. Externally applied Ethylene triggers the natural ripening process of apple, avocado, banana, mango, papaya, pineapple and guava.
In humans, acetylene is not intensely toxic if it is below the permitted levels, whereas if it exceeds the limits, its inhalation can cause unconsciousness and may affect the neurological system by inducing prolonged hypoxia i.e. deficiency of oxygen.
Many countries including India has allowed the use of Ethylene and Ethephon for ripening of fruits as it is less harmful if compared with Calcium carbide. But many petitions have been filed to ban these chemicals too due to the indiscriminate use by the traders and the farmers as they lack the knowledge of their proper use.
But they reason
Though the Government has installed the heating system at Narwal in Jammu and Parimpora in Kashmir to ripe the fruits so as to make these healthier not hazardous but they are reportedly being termed non-functional and limited capacity that affect the seasonal business of the fruit dealers and suppliers.
It is commonly claimed by the fruit suppliers that a significant amount of fruits become undesirable after the process of natural ripening with high weight loss, desiccation and uneven ripening. Thus in absence or dearth of ripening chambers at Mandi Stores, artificial ripening is the only remedy for them.
They do not wait for nature to take its own course of action due to the time and risks involved and thus jump in with unnatural measures. For fruit vendors stocking up of immature fruits is a waste of storage space, waste of time and thus a loss in revenue for suppliers and dealers in the agribusiness. Faster the fruits and vegetables ripen, faster can their marketing be done and faster will the profits be generated.
Moreover, fruit vendors and suppliers claim that artificial ripening not only helps to generate faster revenue for the agriculture industry but also helps keeps prices of these fruits in control. This is because if the demand of these fruits exceeds the supply, it does not take much time for the prices to rocket sky high levels. Thus to accomplish the demand of the consumers many traders resort to the artificial methods of ripening fruits and vegetables.
As mentioned, for fruit traders, the reason for using chemicals is to hasten the ripening process in order to cash-in timely. However, as reportedly claimed by the fruit dealers and suppliers if the authorities do not make available ripening facilities and other services they proceed with the unnatural practices.
The fruit traders often declare that they are using approved chemicals in small quantity, but it is improbable to keep control and check every fruit seller. There urgent need of strategies and measures to curb and contain excessive use of these substances. Following are some of the measures that may help in keeping a check on this menace.
The fruit traders and sellers need to be made aware of the health hazards and instilled with a sense of moral responsibility to the society through awareness of compliance and penalties and punishments for contravention in print and mass media. Restrictions should be strictly imposed and execution of the law should be non-compromising.
Surveillance and vigilance teams should be commissioned before the arrival of climacteric fruit season to trace influx of banned chemicals through tracing chain on the information of vendors. This may be intensified by closure of all non-registered fruit vendors.
For long term solution environmentally safe new compounds which are not harmful to human health must be discovered and tested with collaboration of Agricultural Horticultural Research Institutes. Additionally, more modernised ripening chambers at Mandies should be provided by the government to discourage use of banned chemicals.
Food Activism
Till the time legal authorities come up with a way to effectively stop and prevent this unhealthy and unethical practice, consumers will have to be vigilant and educated. Only increased awareness and activism from the consumers will have the required impact on the market. So it is advisable to update ourselves with the knowledge of healthy food culture and while buying fruits and vegetables following observations be made:
Colour of the fruit: An easily identifiable sign of artificially ripened fruit is that it will have an unnaturally bright colour compared to a naturally ripened one.
Also, in an artificially ripened fruit like mango there will be patches of green that are clearly distinguishable from the yellow and unlike a naturally ripened mango that has a uniform blend of yellow and green.
Similarly, artificially ripened bananas are lemon yellow and their stalks are green compared naturally ripened ones that are dark yellow with small brown or black spots and black stalks.
Taste and aroma: Artificially ripened fruits lack true taste and aroma, while tasting slight burning aftertaste is felt in the mouth with a burning down the throat sensation. While naturally ripened fruits have sweet taste with a lot of juice content.
Texture and colour of the pulp: When cut open, the pulp of a naturally ripened fruit (like papaya, mango) will be uniformly bright reddish-yellow as compared to an artificially ripened one with light and dark yellow pulp.
Self Help
In addition to the judicious choice and conscious approach by the educated consumer, The Food Safety and Standards Authority of India has listed some steps to be followed at home to reduce the level of risk of contamination with harmful chemicals to ensure food safety.
It is advised to select fruits and vegetables without spots or necrosis (lesions) and any abnormality, fruits and vegetables thoroughly with water, preferably running potable water, before eating and cooking.
Encourage peeling of fruits before consumption and vegetables before cooking; it will reduce exposure to pesticide. Also, to minimise the hazards of pesticide residues, the outer leaves of leafy vegetables such as lettuce and cabbage should be discard.
It is advisable to purchase fruits and vegetables from known (registered) dealers and also not to buy fruits when they arrive in the market before the due period that is early and offseason.
Tail Piece
Artificial fruit ripening is a complicated concern particularly in developing countries like India. It needs collective contribution and participation of the entire society, administration agencies, policymakers, fruit-sellers, farmers, scientists and consumers to find an effective, valuable and a viable way out for this serious problem.

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