Fruits and vegetables are highly perishable agricultural products, prone to spoilage and deterioration. Damage often occurs during postharvest handling and transportation. Moreover, the decomposition of fruits and vegetables can generate pathogenic microorganisms that may pose health risks to humans.
Dr. Mohamad Endy Julianto, ST, MT---commonly known as Endy---a lecturer in the Industrial Chemical Engineering Technology (TRKI) Study Program at UNDIP Vocational School, explained that fruit and vegetable preservation has traditionally relied on synthetic chemical fungicides and low-temperature storage. However, synthetic chemicals can eventually accumulate in the human body as the end point of the food chain. Synthetic preservatives have also been linked to allergic reactions in sensitive individuals. Consequently, research into the discovery of natural antimicrobial compounds has grown significantly, as has the demand for such alternatives.
According to Endy, growing consumer demand for safer and higher-quality fruits and vegetables has driven the development of technologies that avoid synthetic chemicals. These include physical treatments such as ultraviolet irradiation, ionizing radiation, biological control methods, active packaging, and modified atmosphere packaging (MAP).
"Among these methods, active packaging has shown outstanding advantages. It is defined as a smart system involving interactions between packaging materials or components and food products or their internal gaseous atmosphere. This system has the potential to meet consumer expectations for safe, fresh, and high-quality products," Endy noted.
Several active packaging systems are widely recognized, including oxygen scavengers, carbon dioxide emitters, moisture absorbers, ethylene absorbers/inhibitors, ethanol emitters, flavor-releasing systems, and antimicrobial coatings. Among these, ethylene absorbers/inhibitors have received considerable attention.
Ethylene acts as a plant hormone, influencing the physiology of fruits and vegetables. It accelerates respiration, thereby speeding up ripening and senescence. The accumulation of ethylene also leads to undesirable changes, such as yellowing in vegetables. "Therefore, removing or inhibiting ethylene within packaging is considered an effective method to preserve fruits and vegetables," Endy explained.
One effective way to inhibit ethylene is through the use of 1-Methylcyclopropene (1-MCP). Ethylene is a gaseous hormone at room temperature, and 1-MCP has attracted researchers' attention because it is effective, environmentally safe, non-toxic, and capable of suppressing ethylene activity even at very low concentrations.
Endy further explained one method of applying 1-MCP: by encapsulating it into paper-based materials. When this paper---coated with encapsulated 1-MCP---is used during transportation or retail display, it gradually releases 1-MCP through moisture adsorption from fruit respiration or the surrounding air. The released 1-MCP competes with ethylene for receptor binding sites, thus preventing the formation of ethylene--receptor complexes and slowing down spoilage.
Typically, ethylene binds to its receptor and forms an ethylene--receptor complex, which triggers enzymatic activities in fruits and vegetables. For instance:
- Pectinase breaks down cell walls, softening the fruit.
- Amylase converts starch into simple sugars.
- Hydrolase degrades chlorophyll, causing discoloration.
By blocking receptor sites, 1-MCP disrupts this chain reaction, thereby extending freshness.
Meanwhile, Endy, elaborated on the mechanism: "MCP binds to the ethylene receptor and prevents the formation of the ethylene--receptor complex. Think of it like a lock and key. The receptor is the lock, ethylene is the key, and MCP is another key that fits into the lock but cannot turn it. Once MCP occupies the lock, ethylene cannot enter, effectively halting the ripening signal."
