نویسندگان
1 گروه مهندسی بیوسیستم - دانشکده کشاورزی- دانشگاه بوعلی سینا - همدان - ایران
2 گروه مهندسی بیوسیستم- دانشکده کشاورزی - دانشگاه بوعلی سینا
3 گروه باغبانی - دانشکده کشاورزی - دانشگاه بوعلی سینا - همدان - ایران
چکیده
کلیدواژه‌ها
موضوعات
عنوان مقاله [English]
نویسندگان [English]
Storage of agricultural products is one of the post-harvest operations. The increase in food waste and the emphasis on fresh consumption of these products doubles the importance of storing them after harvest. Therefore, it is very important to use methods such as a modified atmosphere, edible chitosan coating, and nano packaging film to increase shelf life and maintain the quality of agricultural products. Zucchini is one of the agricultural products that, due to having a lot of water, after a few days of storage, its quality decreases. In this research, the physicochemical and mechanical properties of this product, during the storage period were evaluated by factorial test in a completely randomized design. Zucchini product after harvesting from the farm is covered with 0.5% chitosan solution and with two types of films, including silicone nanoemulsion film and normal, and also in two environments including modified atmosphere (5% oxygen, 10% carbon dioxide, and 85 % nitrogen) and normal atmosphere, packed and stored at 4°C. The storage time for the samples was 20 days. Chemical properties (total soluble solids, pH, titratable acidity, and phenol), physical properties (color changes and weight loss), and mechanical properties (penetration force, elasticity modulus, and penetration energy) were evaluated during the storage period every four days. The results showed that the total soluble solids and color changes (∆E) in the uncoated package containing modified atmosphere and nanofilm had the least changes. The coated package containing a modified atmosphere and nanofilm reduced the changes in pH factors, titratable acidity, weight loss, and penetration force. The modified atmosphere showed a positive performance in reducing the changes of phenol. Also, the combination of modified atmosphere and nanofilm prevented the increase of changes in elasticity modulus and penetration energy.
Introduction
Fruits and vegetables are of particular importance in human nutrition and have significant health benefits. Hence, increasing consumer demand has led to increased focus on the production and quality control of these products. Zucchini (Cucurbita pepo L.) is a common vegetable widely cultivated in temperate regions of Europe, America, and Asia. Zucchini and other agricultural products experience a decline in quality after harvest due to water loss and reduced firmness, which leads to significant economic losses. Post-harvest losses of zucchini increase with improper packaging. When the product is damaged, cellular respiration increases. Increased respiration rate increases ethylene production, accelerates the ripening and aging process, and reduces the quality and shelf life of fruits and vegetables. One of the techniques for reducing waste is the use of appropriate packaging and cold storage to reduce the metabolic activity of agricultural products, which leads to a decrease in respiration rate, ethylene production, microbial activity, and ripening, as a result, it increases the post-harvest shelf life of these products. The use of a modified atmosphere is also very useful in maintaining the quality of the product during the storage period. In this method, the gas inside the package is replaced with a different composition of the atmosphere. This composition includes a low concentration of oxygen and a high concentration of carbon dioxide, which prevents oxidation and microbial spoilage and preserves the quality of the product. Edible coatings such as chitosan are placed as a layer on the product and effectively reduce microbial growth and also act as a barrier against oxygen and moisture, increasing the shelf life of the product. Packaging products with conventional films may not be as effective due to permeability to gases and water vapor, a problem that can be solved by using nano-reinforced materials. A large number of food packaging companies are using nanotechnology to improve moisture and gas barrier properties. This study aimed to investigate the effect of modified atmosphere packaging, chitosan coating, and nanofilm on the quality properties of zucchini at 4°C during storage.
Materials and Methods
The zucchini required in this study were obtained from a farm located in Hamedan city. The zucchini was carefully picked so as not to be damaged and transferred to the Mechanical Properties and Rheology Laboratory of the Faculty of Agriculture, Bu-Ali Sina University, Hamedan. An attempt was made to use samples of the same size, without mechanical or microbial damage. The samples were packaged coated with chitosan powder and uncoated in two packaging films, including a nanofilm made of silicone nanoemulsion purchased from Nano Bespar Aytak Company and a regular film made of light polyethylene, with two types of atmospheres (modified atmosphere with a gas mixture of 5% oxygen, 10% carbon dioxide, and 85% nitrogen, and regular atmosphere). Three zucchinis were placed in each package and stored at 4 °C for 20 days. The experiments were performed every 4 days. The effects of modified atmosphere treatments, chitosan coating, and nanofilm on chemical properties (total soluble solids, pH, titratable acidity, and phenol), physical properties (weight loss and color changes), and mechanical properties (penetration force, elasticity modulus, and penetration energy) at 4°C at the end of 20 days of storage were investigated in a completely randomized design with factorial experiments.
Results and Discussion
Examination of total soluble solids showed that the greatest changes occurred in the uncoated package with normal atmosphere and normal film and the uncoated package with modified atmosphere and nanofilm had the least amount of change. Regarding pH and acidity, the coated package containing modified atmosphere and nanofilm had the least changes, and the most changes were observed in the uncoated package containing normal atmosphere and normal film. The lowest phenol changes were observed at the end of the storage period in the uncoated package containing modified atmosphere and regular film and the phenol changes were greater in the uncoated package containing regular atmosphere and regular film than in the other packages. At the end of the storage period, the highest and lowest ΔE were found in the coated package containing normal atmosphere and normal film and the uncoated package containing modified atmosphere and nanofilm, respectively. The increasing trend of ΔE in packages containing normal atmosphere increased more rapidly. The combination of chitosan coating, modified atmosphere, and nanofilm controlled the weight loss of zucchini, and the uncoated package with normal atmosphere and the normal film had the highest weight loss. The coated package containing a modified atmosphere and nanofilm had a higher penetration force, and the uncoated package containing a normal atmosphere and normal film could not prevent the decrease in penetration force and caused a decrease in the firmness of the samples. The combination of modified atmosphere and nanofilm slowed down the decreasing changes in elastic modulus and penetration energy, and these two parameters decreased in the uncoated package containing normal atmosphere and normal film. In general, storing products in optimal conditions preserves their quality because, under these conditions, their respiration and ethylene production are reduced.
Conclusion
In conclusion, the study effectively demonstrated that using modified atmosphere packaging, chitosan coating, and nanofilm technology significantly enhances the quality preservation of zucchini during storage at 4°C. The results indicated that:
1. Chemical Stability: The combination of modified atmosphere and chitosan coating was most effective in maintaining the chemical properties of zucchini, including total soluble solids, pH, and titratable acidity. The uncoated zucchini in normal atmospheric conditions showed the most significant chemical degradation, underscoring the importance of protective treatments.
2. Phenolic Content Preservation: The preservation of phenolic compounds, which contribute to the nutritional value of zucchini, was optimized in packages utilizing modified atmosphere conditions. The uncoated packages under normal atmospheric conditions exhibited the highest degradation of these beneficial compounds.
3. Physical Quality Maintenance: The visual quality, measured by color changes (ΔE), was best preserved in the uncoated package with a modified atmosphere and nanofilm. In contrast, the normal atmosphere led to more rapid color degradation, emphasizing the role of controlled environments in maintaining product appeal.
4. Weight Loss Reduction: The study highlighted that combining chitosan coating, modified atmosphere, and nanofilm effectively minimized weight loss during storage. The uncoated packages in normal atmospheric conditions experienced significant weight loss, negatively impacting product quality.
5. Mechanical Properties: The penetration force measurements indicated that the firmness of zucchini was best preserved in the coated packages with modified atmosphere and nanofilm. Conversely, uncoated packages in normal conditions showed a decline in firmness, which could affect consumer acceptance.
6. Overall Quality Preservation: The findings suggest that optimal storage conditions—characterized by reduced respiration rates and ethylene production—are crucial for maintaining the quality of fresh produce like zucchini.
The research provides valuable insights into effective preservation strategies for zucchini, highlighting the potential for improved shelf life and quality through innovative packaging methods. Future studies could explore the broader applicability of these techniques across different types of fresh produce to further validate their effectiveness in extending shelf life and preserving quality.
کلیدواژه‌ها [English]
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