Ethylene gas, sourced from various external means like ethylene gas cylinders, compressed

ethylene gas, is commonly used to induce ripening in fruits. However, direct contact between

ethylene gas and fruits is strictly prohibited. Ethylene accelerates the ripening process, leading to

faster and more uniform ripening, which, in turn, reduces the time between harvest and

consumption. This shorter interval can enhance both the quality and nutritional value of the fruit.

Nevertheless, some fruits are sensitive to ethylene and may experience premature decay if exposed

to it. Additionally, fruits ripened with ethylene may lack the distinctive flavor and aroma of

naturally ripened counterparts. Furthermore, continuous respiration and ethylene emission

contribute to a decline in both nutritional and sensory qualities, along with a decrease in

postharvest shelf life.

2.2.1. Calcium Carbide

Calcium carbide (CaC2) is a versatile chemical compound widely used in various industries. It

exists as a colorless solid in its pure form but is commercially available as a grey or brown technical

grade. CaC2 is widely employed ripening agent in the developing countries, releases acetylene gas

which is an analog of ethylene, but is often contaminated with harmful impurities such as arsenic,

phosphorus, calcium, phosphide and silicon carbide (Danish et al. 2015; Gasik et al. 2013). Furthermore,

CaC2 is widely used for fruit ripening in many regions outside the U.S. to artificially ripen fruits, primarily due to its affordability and widespread availability. While it offers advantages such as facilitating early fruit harvesting, accelerating color and taste development, and ensuring off-season fruit availability, its use comes with significant drawbacks (Igbinaduwa et al. 2018; Islam et al. 2016; Siddiqui and Dhua, 2010). Additionally, artificially ripened fruits are softer, less delicious, and have shorter shelf lives (Ubuh et al. 2022; Okeke et al. 2022).

(Bhadoria et al. 2018). Apart from its role in fruit ripening, ethephon also used as a plant growth regulator. It has been reported to increase fruit size, induce flowering, enhance color, and prompt flower abscission (Ali and Baidya, 2021; Bhadoria et al. 2018). Therefore, ethephon has a wide range of applications in agriculture and horticulture, making it an essential chemical compound in the industry. Its effectiveness can be influenced by environmental factors such as light, humidity and temperature. Compared to calcium carbide, Ethephon is often seen as preferable for fruit ripening as it requires less time to mature fruits like banana, tomato and pineapple. However, the choice between Ethephon and calcium carbide may depend on various factors, including the specific type of fruit, environmental conditions, and regulatory guidelines.

Ethylene glycol is a colorless, odorless, and sweet-tasting liquid commonly used as an industrial coolant and antifreeze formulations, has been explored as a fruit ripening agent (Hassan, 2016). When diluted with water, it can ripen fruits (Banana, tomato, apple) quicker than their regular ripening rate, particularly in colder climatic conditions. Ethylene glycol solution is applied to the fruits, and as it breaks down, it releases ethylene gas, which triggers the ripening process. Compared to other ripening agents it ripens fruits faster in cold conditions (Maduwanthi & Marapana, 2019) While the use of ethylene glycol for fruit ripening has shown promising results, it is crucial to exercise caution as the compound is highly toxic to humans and animals cause damage to kidney and liver when ingested Goonatilake, 2008).

Methyl jasmonate, a naturally occurring plant hormone, contributing to improved fruit quality without reported toxicity for human consumptions (Concha et al., 2013; Wang et al., 2018). The limited use of methyl jasmonate in fruit ripening compared to calcium carbide and ethephon is primarily due to regulatory considerations, differences in effectiveness, specific applications, cost and consumer perception. Efforts in research and agriculture continue to explore the potential benefits of methyl jasmonate while addressing its limitations (Baek et al., 2021; Garcia-Pastor et al., 2020).

Various additional chemical compounds are routinely employed as artificial ripening agents for fruits. These compounds have various chemical properties and modes of action, but share the common goal of increasing the ripening process of fruits (Singal et al., 2012). Acetylene is a gaseous hydrocarbon which is an analog of ethylene that is used as an artificial ripening agent for

fruits such as bananas, mangoes, and papayas. (Nura et al. 2018). Additionally, propylene, another

colorless gas, is also used in the food industry as a ripening agent. It is primarily used to ripen

tomatoes and melons, but the activity of propylene is only 1% of that of ethylene (Aworh, 2021). Methanol, a poisonous alcohol, is used in small quantities to accelerate the ripening of some fruits, including bananas and tomatoes (Islam et al. 2018). Potassium permanganate is a powerful

oxidizing agent that can be used as a ripening agent for bananas and tomatoes (Alvarez-Hernandez et al. 2019). It is important to be aware of the potential health and safety risks associated with the use of these agents and to ensure that they are used in a safe and responsible manner. However,

due to toxic in nature such chemicals should not be used for ripening purposes.