Controlling CO₂ concentration improves post-harvest product preservation

In the export sector of cherries, especially with delicate varieties such as Regina, the preservation of color and flavor is crucial. The Post Harvest Department of Paclife is dedicated to the analysis and understanding of the factors causing issues like pulp browning and sour taste, commonly observed in this variety.

Regina, due to its increased metabolism and tendency to darken, faces significant challenges in terms of quality and acceptance in international markets. One of the key aspects to address these challenges in the post-harvest environment is the precise control of gases within an intelligent packaging, essential to maintain the product’s freshness and quality until its final destination.

Advantages of Paclife MAP Packaging

Paclife has developed an innovative packaging technology using zeolites, a microporous mineral with remarkable capacity to regulate oxidation by adsorbing gases and moisture. This approach creates a controlled atmosphere, essential to keep Regina cherries in optimal conditions during transport and storage.

Although zeolite offers advantages for climacteric fruits, such as the absorption of ethylene in the case of kiwis, its application in cherries, which are non-climacteric fruits, has an equally significant impact.

In this case, zeolite helps slow down the activity of the polyphenol oxidase (PPO) enzyme, whose main function is to catalyze oxidation reactions when exposed to oxygen. By controlling these processes, zeolite not only prevents fermentation but also regulates the presence of oxygen, which is fundamental to reduce pulp browning and maintain the quality of fruits during commercialization.

Another crucial aspect in preserving Regina cherries is the permeability of the bags, specifically adapted to the needs of this variety. We know that maintaining a controlled balance between oxygen (O₂) and carbon dioxide (CO₂) is essential to significantly reduce browning, a common issue for this fruit.

However, using high humidity bags alone is not sufficient, as they only prevent dehydration without directly impacting the fruit’s freshness. Paclife has developed an intelligent solution to create this controlled atmosphere by precisely regulating gas levels.

Studies have shown that a higher concentration of CO₂ in the packaging delays ripening and extends the fruit’s shelf life, while controlled levels of O₂ are crucial to minimize the risk of internal browning and loss of firmness, thereby ensuring the cherry’s quality during transport and storage.

By developing an intelligent packaging that combines permeability modeling adapted to the product's respiration rate with the use of zeolite, we have achieved more controlled oxygen levels, even under suboptimal handling conditions.

This approach is particularly crucial in cases of thermal fluctuations during transport or at the final destination, as it prevents fermentation and significantly reduces the incidence of browning. In summary, controlled management of low oxygen levels is essential to preserve product quality, ensuring it reaches the final consumer in the best possible condition.

Graph 1 shows the gas curves (oxygen and carbon dioxide) of the Regina variety during a 45-day storage period at 0°C, followed by a thermal break at room temperature for 72 hours.

Image 1: Gas concentration 45 days after packaging + 72 hours after breaking at room temperature. Var. Regina. PacLife vs. other MAP packaging providers. Size 2JD.

The T0 treatment (PacLife MAP) demonstrates exceptional ability to maintain stable gases during the first days of packaging, achieving safe results even after cold start and thermal break evaluations.

The T1 (High Moisture MAP Package), on the other hand, shows low controlled atmosphere formation in the early days, but despite this initial condition, gas levels reach more risky values during the thermal break. Finally, T2 (MAP package without PacLife technology) achieves stable gas formation in the first days of packaging but fails to withstand thermal fluctuations, leading oxygen and carbon dioxide levels to become dangerous.

These last two treatments demonstrate that modeling gases solely based on the number of perforations in the packaging is not sufficient; the permeability and the technology used in its design play a crucial role in proper product preservation.

Graph 2 shows the correlation between carbon dioxide levels and the product's respiration rate, highlighting a strong relationship between the two factors. It is important to note that as carbon dioxide levels increase, the fruit's respiration rate decreases.

This phenomenon is fundamental to maintaining optimal post-harvest conditions, as a lower respiration rate helps preserve the product's freshness and quality. However, this is only possible with appropriate technology to ensure controlled gas levels, even under adverse conditions such as temperature fluctuations or transport in non-ideal environments.

Image 2: Correlation between CO2 concentration during MAP cold pause and respiration rate. Tests on Ce var. Regina (40 days at 0°C). Graph 2: There is a correlation between CO2 equilibrium percentage and respiration rates analyzed at the end of storage. Higher CO2 results in lower respiration rates.

Browning in Regina cherries is influenced by various factors such as temperature, respiration rate, skin damage, acidity, and pH, which directly affect both the fruit's taste and appearance. For example, under conditions of excessively high or low pH, polyphenol oxidase (PPO) enzyme activity intensifies, triggering the pulp browning reaction.

In recent years, Paclife has invested in researching these conditions and developing packaging solutions tailored to the specific needs of each variety. Using packaging designed with its patented technology, it has significantly reduced browning incidence and improved the pedicel's appearance, keeping it green and fresh—an essential quality indicator in demanding markets like China.

The following photos show a comparison of results obtained from Graph 1, highlighting a lower incidence of browning in the PacLife MAP treatment (T0). The differences obtained are statistically significant in both cold start and thermal break evaluations, as shown in Table 1.

Table 1: Different letters indicate significant differences among varieties according to Fisher LSD (p≤0.05), for each evaluation date.

With these developments, Paclife continues to lead in the creation of intelligent packaging, supported by rigorous statistical analyses and empirical data that allow us to offer customized and effective solutions for every need. Precise gas management has emerged as a key element for cherry preservation, and packaging specifically designed for the Regina variety has proven essential to maintaining its quality, freshness, and distinctive flavor until it reaches the final consumer.

Furthermore, every year we expand the evaluation parameters of our research, applying them to various fruits with exceptional results. For example, we have made significant progress with D'Agen plums and Cherry Plums, which have been highly appreciated by our customers and the industry. These innovations reinforce the role of the research and post-harvest department as a strategic pillar for understanding and meeting the growing demands of the agri-food sector.

Source: Poscosecha
Images: PACLIFE; Poscosecha

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