Nutritional benefits, post-harvest challenges, and innovative preservation strategies of onions (Allium cepa L.): A comprehensive review

Onions spoil when they start to break down, which affects their safety, taste, texture, and appearance. This happens mainly due to bacteria or enzymes, causing bad smells, color changes, softness, and off flavors as shown in Table 4. Several factors contribute to spoilage, including physical damage, temperature changes, humidity, and the release of ethylene gas (Petropoulos et al., 2016). Storing onions above 18°C encourages bacteria growth, while storing them below 4°C can cause freezing damage, making them weaker and more vulnerable to pathogens (Palta et al., 1977). High humidity promotes mold and softness, while low humidity causes onions to dry out and lose flavor (Qiu et al., 2022). Physical damage speeds up spoilage, and improper storage can lead to sprouting (Shekhawat et al., 2022).

Humidity plays a significant role in the spoiling of onions. High humidity promotes microbial growth, leading to mold formation and softening of the onions, while low humidity causes moisture loss, resulting in shriveling and flavor loss (Qiu et al., 2022). Physical damage, such as punctures or bruises, provides entry points for microbes, accelerating the spoilage process (Mishra et al., 2014). Improper storage can also lead to sprouting, as the production of ethylene triggers ripening, which causes loss of texture and the development of undesirable compounds, further diminishing the quality of the onions (Shekhawat et al., 2022).

Microorganisms such as Erwinia carotovora contribute to soft rot in onions by producing enzymes that break down cell walls, leading to mushy, discolored tissue and unpleasant odors (Doyle, 2007). Similarly, Enterobacter species, which thrive in high humidity and temperatures, can ferment onions, causing off-flavors and hastening decomposition (Salem et al., 2006). Fungal pathogens, including Aspergillus species, Penicillium species, and Botrytis cinerea, are also major contributors to onion rot (Gruber-Dorninger et al., 2017). Aspergillus species are responsible for mold rot and aflatoxin production, a carcinogenic mycotoxin (Alina, 2022). Furthermore, yeasts like Saccharomyces cerevisiae also contribute to spoilage by fermenting sugars and producing off-flavors under anaerobic conditions (Parapouli et al., 2020).

According to Orpin et al. (2017), various bacteria, including Escherichia coli and Pseudomonas species, as well as fungi like Aspergillus, are linked to onion rotting. Microbial growth is exacerbated by environmental factors such as temperature, humidity, and physical damage (Tang et al., 2015). Therefore, proper handling, storage, and cleanliness are essential to reduce contamination and extend onion shelf life (Ehuwa et al., 2020).

Several biological, chemical, and environmental factors contribute to onion spoilage, reducing both quality and shelf life (Qiu et al., 2020). A primary cause of spoiling is enzymatic breakdown, where enzymes like cellulases and amylases degrade cellulose and starch in the cell walls, weakening the onion’s structure (Araji et al., 2014; de Souza and Kwaguti, 2021). This makes the onion softer, making it more vulnerable to microbial invasion and accelerating spoilage (Mishra et al., 2014). Another enzyme, polyphenol oxidase (PPO), is linked to enzymatic browning, which makes onions brown when exposed to air, diminishing their appearance and marketability (Zhang, 2023). Polyphenols contribute to both enzymatic and non-enzymatic browning, leading to undesirable tissue discoloration when the onion’s cellular structure is damaged (Singh et al., 2018).

Dehydration is another significant factor in spoilage. Onions shrink under low humidity, affecting their flavor and texture, and making them more prone to contamination and damage (Gorrepati et al., 2017). Improper storage conditions further decrease firmness and increase bruising risks (Tournas and Katsoudas, 2015). Additionally, gas exchange and respiration after harvesting deplete nutrients and accelerate aging, especially at high temperatures (Sun et al., 2023). The production of ethylene during storage causes sprouting and enzymatic alterations, further deteriorating onion quality (Julianti et al., 2013).

Sun drying is one of the oldest and most energy-efficient methods of preserving onions, particularly in regions with abundant sunlight (Misha et al., 2013). However, it is weather-dependent, time-consuming, and exposes onions to environmental contaminants. This method remains common in resource-limited rural and developing areas (Ahmed et al., 2013). Sontakke and Salve (2015) observed that while sun-dried onions retain some nutritional value, they may lose part of their flavor and aroma compared to modern drying techniques.

Anbukkarasi et al. (2013) found that using the windrow method sun drying onions for four days followed by a 21-day curing period in sheds reduced sugar content while enhancing storage life and minimizing losses. A faster alternative is air drying, or hot-air drying, which involves exposing onions to warm air at controlled temperatures. However, improper execution can lead to flavor and nutrient loss. To preserve essential minerals and antioxidants while maintaining flavor.

Sophisticated drying methods, including vacuum, infrared, microwave, and freeze-drying, have improved the preservation of fruits and vegetables, including onions (Hasan et al., 2019). Freeze-drying, or lyophilization, maintains the onion’s natural nutrients, flavor, and structure by freezing the onions and then applying low pressure, causing the ice to sublimate. Hamed and Foda (1966) found that onions freeze-dried at -30°C for 7-8 h under 6.1 mm Hg pressure retained superior color, flavor, and nutritional content compared to conventionally dried onions.

Microwave-vacuum-freeze drying is a rapid and cost-effective method for drying onions (Abbasi and Azari, 2009). Reis et al. (2022) reported that freeze-drying and multi-flash drying techniques effectively preserve the color, texture, and rehydration qualities of vegetables, including onions. Microwave drying, which uses electromagnetic waves, is more efficient than hot air drying, retaining more nutrients and bioactive compounds (Mitra et al., 2010). Hoover drying, often combined with freeze or microwave drying, operates at lower pressure, reducing oxidative damage and preserving essential nutrients (Parikh, 2015). Additionally, vacuum drying has been shown to be particularly effective in maintaining the color and bioactive components of onions (Calin-Sánchez et al., 2020).

Solar-assisted drying is becoming an increasingly popular and sustainable method for drying onions, particularly in regions with abundant sunlight. By combining solar energy with mechanical systems like fans and heaters, the drying process becomes faster, more efficient, and consistent, while also reducing environmental impact. Solar-assisted drying can be achieved using direct or indirect drying methods as shown in Fig. 4. Nwankwor et al. (2021) found that solar-assisted systems, when used alongside traditional methods like air or hoover drying, significantly reduce drying times without compromising product quality.

Fig. 4. Direct and indirect solar drying-direct solar drying (A) and indirect solar drying (B). Adapted from Abhay et al. (2017) and Nwankwor et al. (2021).

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Another advanced technique is superheated steam drying shown in Fig. 5, which uses steam at temperatures higher than boiling to extract moisture from onions. This method enhances rehydration, accelerates drying, and helps retain the onion’s nutrients, color, and aroma. Sehrawat et al. (2016) demonstrated that superheated steam drying preserved the flavor and aroma of onions while using less energy and reducing drying time compared to traditional techniques.

Fig. 5. Superheated steam drying setup. Adapted from Nwankwo et al. (2021) and Sehrawat et al. (2016).

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Hot air-assisted infrared drying is an energy-efficient method that heats the onion’s surface using infrared radiation (Askari et al., 2013). This technique, which exposes onions to electromagnetic radiation with wavelengths from 0.8 to 1,000 μm, is faster and uses less energy than conventional hot-air drying. Boudhrioua et al. (2009) found that infrared drying preserves flavor and texture while removing moisture quickly, ensuring the retention of nutritional value.

The most popular technique in industry for freezing onions is air-blast freezing. In a blast freezer, the onions are exposed to cold air, usually at a temperature of -18°C to -30°C (Dempsey et al., 2012). By preventing big ice crystals from accumulating inside the cells, this rapid freezing method helps maintain the texture and flavor of the onion. Uneven freezing, however, may occur if not properly managed. According to Jung et al. (2015), air-blast freezing produced the tiniest ice crystals, caused the least amount of cell damage, and lost the least amount of organic acids, sugar, and vitamin C.

Onions can be frozen using liquid nitrogen using a process called cryogenic freezing, which is becoming more popular since it can increase quality and prolong shelf life. The controlled environment established by liquid nitrogen prevents microbial growth (Mascheroni, 2000; Wande and Shinde, 2013). However, cryogenic freezing is usually reserved for high-value products like seafood or specific fruits and is not cost-effective for most crops. Additionally, issues like product cracking and recrystallisation may arise. Agnelli and Mascheroni (2002) discovered that by shielding the cell walls from harm, cryogenic freezing aids in maintaining the food’s shape.

When vegetables freeze, ice crystals form because of points created by heat and mass transfer. The size and structure of these crystals depend on how long freezing takes and how much the temperature drops below freezing (You et al., 2021). Larger ice crystals can damage the food’s texture and quality.

Recent freezing technology advancements aim to improve food quality and efficiency. One of these is high-pressure freezing (HPF), which lowers the freezing point of water by applying pressure up to 210 MPa. This promotes faster freezing and smaller, more uniform ice crystals, reducing damage to the food (Li et al., 2018). HPF improves the texture and structure of frozen fruits and vegetables. It includes techniques like High Pressure Induced Freezing (HPIF), High Pressure Shift Freezing (HPSF), and High Pressure Assisted Freezing (HPAF) (Cheng et al., 2017).

Freezing alone does not always improve food texture (Chaudhary, 2021). However, combining high-pressure freezing with ultrasound technology, which operates between 20-100 kHz, enhances freezing. Ultrasound speeds up the process by promoting ice formation, improving heat transfer, and creating bubbles that speed up freezing (Zheng and Sun, 2006). Kiani et al. (2015) found that this process improves food preservation. Additionally, Roldán-María et al. (2009) discovered that low temperatures and specific pressures increase the antioxidant levels in onions.

By lowering the moisture content of onions, drying is a common and traditional way of preservation that helps stop the growth of bacteria and enzymes that cause spoiling (Pandiselvam et al., 2021). Drying increases onions’ storage stability by bringing their moisture content down to less than 10%. A variety of drying techniques are frequently employed, including hoover, air and freeze drying (Ahmed et al., 2013). However, dehydrating whole onions or onion fragments results in significant flavor component losses, according to Freeman and Whenham (1975). As was covered before in this review, more recently, sophisticated drying methods such as microwave, infrared, and radiofrequency drying have drawn interest due to their quicker heating times and superior food preservation capabilities.

Conventional onion storage typically depends on ambient factors such as dry, cool, and well-ventilated spaces. To keep moisture from building up, onions are sometimes stored in bags, baskets or bins that let air circulate. Onions must be stored properly to prevent sprouting and maintain freshness; the ideal range is 4-10°C with a humidity of 65-70% to minimize moisture absorption and spoiling. To increase airflow, onions can be braided or kept in mesh bags or hanging bundles in homes or rural areas. This approach is straightforward and economical, but it is only appropriate for temporary storage and is dependent on the ambient conditions. Sprouting or rotting may result from excessive heat or humidity (Sharma et al., 2021).

Onions are preserved using an age-old technique called pickling, which involves submerging them in a solution of vinegar, salt, and occasionally sugar or spices to create an acidic environment that inhibits the growth of bacteria. Usually kept in jars, pickled onions add a tart flavor and can be consumed within a few days or weeks. They become a popular addition to salads, sandwiches, and side dishes because of this process, which also improves their flavor and prolongs their shelf life for months. Pickling onions increases their health advantages by preserving antioxidants like flavonoids, according to research (Irmak et al., 2017; Soni et al., 2022). Kark (2017) also discovered that pickled onions contained more pyruvic acid.

Onions are preserved using the classic smoking method, which involves exposing them to smoke from burning wood or other organic materials. In addition to drying the onions and adding antimicrobial elements that aid in their preservation, this method gives them a distinctly smokey flavor. The onions can keep their freshness for long periods of time since the gradual drying process keeps them from spoiling. Onions could be hung in smokehouses or smoked over wood chips. The smoke’s antibacterial and antioxidant qualities extend the onions’ shelf life and keep them fresh for several months. In rural places where refrigeration is scarce, this method is particularly helpful (Alba et al., 2020).

Fermentation is a well-established preservation method that leverages the activity of beneficial microbes, like lactic acid bacteria, to produce acids that prevent spoilage. Onions are typically left to ferment for several days or weeks after being submerged in a brine or saltwater solution. During this process, lactic acid is produced, which helps preserve the onions and imparts a distinct sour, acidic flavor. Ramadevi et al. (2010) investigated the preservation of onions through lactic acid fermentation using varieties such as Arka Niketan, Arka Bindu, and White Onion. They found that when lactic acid bacteria were combined with 25% cider vinegar, the Arka Bindu variety had the lowest pH and the highest acidity. Fermented onions, rich in probiotics, offer additional health benefits, particularly for gut health (Khorasani et al., 2019). This natural preservation method not only extends shelf life but also enhances the nutritional value of onions by enriching them with beneficial microorganisms.

Onions can be preserved easily and successfully by storing them in vinegar or oil. By peeling, cutting, and submerging onions in vinegar or oil, this method creates an anaerobic environment that inhibits the growth of dangerous germs, such as Clostridium botulinum. This method is frequently employed in Middle Eastern and Mediterranean cooking, where onions are frequently marinated in olive oil and spiced with different herbs. Although this technique can greatly increase the onions’ shelf life for weeks or even months, it is crucial to adhere to appropriate storage and hygiene procedures to avoid infection (Irmak et al., 2017).

An innovative preservation technique called Controlled Atmosphere Storage (CAS) maximizes the storage conditions to preserve onions’ quality for extended periods of time. CAS extends shelf life by modifying atmospheric conditions, such as preserving 3 kPa O₂ and 5 kPa CO₂, which slows respiration, postpones senescence, prevents pathogen growth, and lowers ethylene production (Chávez-Mendoza et al., 2016; Chope et al., 2007b). By allowing onions to be sold during off-seasons, CAS provides financial advantages while being more costly than traditional refrigeration.

While higher temperatures (24°C or 30°C) are unsuitable for commercial usage, CAS storage at circumstances such 1% O₂ and 99% N₂ at 5°C can retain onion quality with little flavour changes (Yoo et al., 2012). According to Praeger et al. (2003), onions exhibit a 2.8% weight loss after 36 weeks at 1% O₂, which is much less than the 1% loss every 9 weeks under ambient storage conditions. It has also been noted that different varieties react differently to CAS. According to Bansal et al. (2015), the ‘Carlos’ variety exhibits decreased Total Soluble Solids (TSS) under CAS, whereas the ‘Caramelo’ variety maintains its best marketability under controlled refrigeration. In areas like Southern India, where it helps lower postharvest losses during the monsoon season, CAS has shown benefits (Gomathy et al., 2019).

A cutting-edge and eco-friendly technology, cold plasma has been popular in the agri-food sector since it is affordable and can enhance food quality and safety (Pankaj et al., 2018). Microorganisms are successfully rendered inactive by cold plasma, which operates at moderate temperatures and produces a variety of vaporous species with high-energy electrons that can reach temperatures of up to 20,000 K (Misra et al., 2011). This method keeps food’s nutritional value and flavor intact while extending its shelf life.

According to Misra et al. (2016), cold plasma treatment has shown great promise in preserving food integrity and getting rid of dangerous microbes. Terebun’s 2021 study on plasma treatment of onion seeds revealed no discernible surface alterations under a microscope, indicating that the method may successfully maintain the seeds’ properties. This demonstrates the potential of cold plasma as a non-invasive, sustainable food preservation method without sacrificing quality.

In the food business, essential oils are becoming more and more recognized as creative and sustainable preservatives that provide a greener substitute for conventional preservation techniques (Ju et al., 2019). Thyme, oregano, and clove oils have potent antibacterial qualities and can be applied as coatings to onions to prolong their shelf life. These coatings create a barrier that keeps bacteria from growing, lessens dehydration, and keeps onions fresher longer. Onions are also a good preservation option since essential oils help maintain their nutritional content and flavor. According to Esmaeili et al. (2023), essential oils have strong antibacterial properties and have been shown to be effective against pathogens such as Listeria monocytogenes, Escherichia coli, and Staphylococcus aureus.

According to a study by Kumar et al. (2021), gamma irradiation effectively preserved onions by reducing contamination and delaying sprouting, while also maintaining their quality. Despite safety concerns, research suggests that controlled doses of irradiation are a safe and effective method for preserving onions. Irradiation is a technique that exposes food to ionizing radiation to eliminate bacteria, pests, and spoilage microorganisms. This method has been thoroughly studied for extending the shelf life of various produce, including onions.

Using high-frequency, high-intensity sound waves that can penetrate food materials, ultrasound treatment provides a straightforward, affordable, and effective substitute for other cutting-edge technologies. By creating disruptions in solid particles in a solution, the technique breaks them apart and allows them to diffuse into the solvent (Cares et al., 2010). The extraction of bioactive substances and the preparation of fruit and vegetable pastes and juices are only two of the many foods’ processing uses for ultrasound. The total phenolic content of spices has also been measured more recently using ultrasound (Teng et al., 2019).

Nanotechnology has become a promising approach for food preservation, employing nanoparticles and nanomaterials to interact with food at the molecular level (He et al., 2019). Advances in nano emulsions, nanocomposites, and nanocoating have improved the antimicrobial and antioxidant properties of food coatings, significantly extending the shelf life of onions. Natural polymers such as chitosan, known for their antimicrobial and antioxidant benefits, are also being explored for preservation purposes (Yuan et al., 2016).

Research by Younes (2020) found that incorporating nano-silver into carboxymethyl cellulose effectively preserved fresh and dried onions by inhibiting microbial growth, enhancing pungency, and maintaining color. Additionally, mild heat treatments and edible alginate-based coatings have been shown to slow respiration rates and delay onion deterioration (Medino-Jaramillo et al., 2022). However, the high cost of silver nanoparticles limits their large-scale application. To address this, researchers are exploring alternative nanomaterials. Copper nanoparticles offer a cost-effective antimicrobial solution, while zinc oxide nanoparticles, known for their broad-spectrum antimicrobial properties, provide an affordable and effective option for preserving perishable foods (Jin and Jin, 2021; Solangi et al., 2024). These innovations in nanotechnology offer sustainable alternatives to conventional preservation methods, ensuring better onion storage without compromising quality.

Postharvest losses in onions, caused by factors such as rotting, sprouting, and physiological weight loss, drastically limit their shelf life and diminish their quality. Elevated temperatures and high humidity exacerbate these problems, particularly during the rainy season. One promising approach to addressing these issues is gamma irradiation. Different gamma irradiation dosages (0 Gy, 10 Gy, 60 Gy, 100 Gy, and 200 Gy) were examined on onion bulbs kept at room temperature in a study by Sharma et al. (2020). According to the results, irradiation at 120 Gy successfully decreased weight loss, rotting, and sprouting, prolonging the onions’ shelf life for up to three months.

Additionally, irradiation onions maintained their freshness and firmness while exhibiting little decline in their levels of pyruvic acid, ascorbic acid, and total soluble solids. Onion quality was best preserved by radiation at 120 Gy, which provided a workable way to lower postharvest losses and guarantee longer storage.

Onions are chemically preserved using fungicides and antimicrobial chemicals to stop the growth of bacteria, yeasts, and fungus that can cause rot and reduce quality. Onions can be effectively protected from fungal diseases such as Botrytis alli-induced neck rot and postharvest spoilage from fungi like Penicillium and Fusarium by using fungicides like thiabendazole, prochloraz, and fluazinam. Onions are also sanitized using peracetic acid, a mixture of acetic acid and hydrogen peroxide, which increases food safety and prolongs their shelf life. Along with carbendazim, acetic acid and sulphur dioxide fumigation also aids in lowering fungal infestation.

Studies have demonstrated that plant extracts, especially those derived from Moringa oleifera and other spices, have antifungal properties that can reduce spoiling (Arowora and Adetunji, 2014; Kumar et al., 2015). These techniques offer practical ways to maintain the quality of onions and guarantee food safety while they are being stored and transported.

Onions’ ripening and aging are influenced by ethylene, a plant hormone that accelerates premature sprouting, leading to waste and quality degradation. To address this, ethylene inhibitors are used to prevent sprouting and extend shelf life. The effectiveness of ethylene scavengers depends on factors such as the surface area of the substrate and potassium permanganate content (Taylor et al., 2012). 1-Methylcyclopropene (1-MCP), a common ethylene inhibitor, blocks ethylene receptors, preventing the plant’s response to the hormone. Studies show that 1-MCP helps maintain flavor, texture, and overall quality while delaying sprouting (Downes et al., 2010). Additionally, fungicidal treatments like thymol can reduce spoilage by up to 96% (Ji et al., 2018). Maleic hydrazide, once commonly used to inhibit sprouting, was banned in 2009 due to health concerns, prompting research into safer alternatives, such as combining it with carbendazim to control fungal infections and rotting (Kumar et al., 2015). These approaches help preserve onion quality during storage.

Salt and sugar have been traditional preservatives for food, including onions, by creating conditions that prevent microbial growth through osmosis, which removes moisture. Salting reduces water content, inhibiting microorganism growth (Albarracin et al., 2011). High salt concentrations disrupt microbial cell membranes and enzymatic reactions, making the environment unsuitable for spoilage. To further enhance preservation, salting is often combined with boiling or drying. It also improves the flavor, texture, and aroma of onions. In brine preservation, onions are submerged in saline solutions, which dehydrate them and prevent bacterial growth (Sebranek, 2009).

Another classic preservation method is dipping onions in sugar or syrup to encourage dehydration. Osmotic dehydration pretreatments significantly affect drying rates, water loss, solid gain, and the retention of vitamins and minerals. According to Alabi et al. (2016), osmotic treatment with a 20% w/w solution at 50°C for 120 min, followed by drying at 60°C, maximized solid gain and iron content, improving the quality of preserved onions.

Onions are frequently packaged in mesh bags composed of materials like nylon, kenaf, or polypropylene. These bags provide adequate ventilation, which lowers the chance of decay and helps avoid moisture accumulation. They are a popular option for retail packaging since they are affordable, long-lasting, and simple to use (Murumkam et al., 2018). In contrast to other packaging techniques, mesh bags do not provide protection against physical damage, dust, or pests, all of which can reduce the shelf life of onions.

Shehu et al. (2023) investigated how postharvest losses from onions were affected by both conventional and improved storage methods. They discovered that onions kept in jute bags sprouted at a significantly lower rate (22%) than onions kept in mesh bags, suggesting that jute bags may be useful for lowering sprouting and enhancing storage quality.

Onions are traditionally packaged in paper and burlap bags, which offer a ventilated environment that preserves flavor and texture. Eco-friendly and biodegradable materials like wood, plants, or recycled paper are frequently used to make these sacks. Paper packaging is a common option in the food business because of its mechanical strength, recyclability, and affordability (Deshwal et al., 2019; Otto et al., 2021). The shelf life and quality of onions stored in paper and hessian sacks may be impacted since they are more likely to rupture than mesh bags and provide less defense against moisture or pests. Notwithstanding these disadvantages, paper and burlap sacks are an attractive and sustainable alternative for packing onions due to their cost-effectiveness and environmental advantages.

Onions are frequently packaged in plastic film due to its flexibility, resistance to punctures, and capacity for secure sealing, particularly in consumer markets. In packaging, materials like high-density polyethylene (HDPE) and low-density polyethylene (LDPE) are commonly utilized, especially in Modified Atmosphere Packaging (MAP), which controls the air conditions surrounding onions to prolong their shelf life. These films come in flexible, semi-rigid, and rigid forms, and they are also utilized for comparable purposes with other materials as polyester (PET), polypropylene (PP), and polyvinyl chloride (PVC).

Although plastic films are useful for keeping perishables fresh and preventing spoiling, their non-biodegradability raises environmental issues and contributes to the accumulation of trash over time (Salame, 1986; Van Willige et al., 2002). As a result, there is growing interest in packaging alternatives that are more environmentally friendly.

As an eco-friendly and efficient way to package onions, edible coatings are growing in popularity. These coatings, which are made from natural materials like carnauba wax, beeswax, and chitosan, provide a thin, biodegradable layer that guards against microbial contamination and helps stop moisture loss. The antibacterial qualities of chitosan-based coatings are very noteworthy, and they are crucial in prolonging the onions’ shelf life. Packaging materials made of nanocomposite materials are becoming more popular in addition to edible coatings. By adding nanoparticles to conventional packaging, these materials improve mechanical strength, antibacterial qualities, and the capacity to identify foodborne pathogens and other important analytes. Food packaging solutions that are more efficient and sustainable are being developed because of these advances (Donglu et al., 2016; Iduma and Obele, 2021; Sharma et al., 2017).

Active packaging is a cutting-edge technique that enhances food preservation by incorporating elements within the packaging to actively interact with the contents. In contrast to traditional packaging, active packaging carries out specialized tasks such scavenging hazardous gases, managing moisture, releasing advantageous substances, and controlling temperature to enhance food quality and safety. Active packaging for onions can include oxygen scavengers, moisture absorbers, or antimicrobials, all of which help to prolong shelf life. Examples include moisture control, which maintains ideal humidity and minimizes spoiling, and oxygen scavengers, which inhibit the growth of mold and sprouting. The quality of onions is further preserved by this method, which also aids in preventing microbial contamination (Kuswandi et al., 2020; Lee et al., 2019; Singh et al., 2019).

An inventive method for tracking and providing real-time information on the state of packed goods is intelligent packaging, which incorporates sensors or indications. Intelligent packaging helps minimize food waste, guarantee consumer safety, and boost the general effectiveness of the food sector by identifying changes in the product’s environment. Numerous parts of this technology, including data carriers, sensors, and indicators, improve supply chain management and offer insightful information on product quality. To ensure optimal quality from production to consumption, time-temperature indicators help track exposure to unfavorable conditions, while ethylene gas sensors can identify sprouting in onions (Kalpana et al., 2019; Müller and Schmid, 2019). Throughout the supply chain, these developments are essential to preserving the safety and freshness of onions.