Document Type : Research Article
Authors
1 Ferdowsi university of mashhad
2 university of TorbathHeydarieh
Abstract
Cherry tomato (Solanum lycopersicum cultivar Azar) is one of the most popular tomato varieties, highly valued for its small size, sweet taste, and versatile use in salads, dishes, and food garnishes. This fruit is not only visually appealing but also nutritionally rich, containing essential compounds such as vitamin C, which contribute to its high nutritional value. However, cherry tomatoes have a short postharvest life due to their susceptibility to microbial spoilage. Therefore, developing effective methods to preserve quality and extend the shelf life of this product is of great importance. In this context, the use of edible coatings, natural antimicrobial compounds, and nanoemulsion technology can be considered as promising approaches. This study aimed to investigate the effects of Plantago psyllium mucilage, marjoram essential oil, and their nanoemulsion combination on the physicochemical, microbial, and sensory characteristics of 'Azar' cherry tomatoes during 28 days of storage at 4°C. The results showed that the nanoemulsion containing Plantago psyllium mucilage and marjoram essential oil, with a particle size of 219.3 nm, zeta potential of -40.5 mV, and polydispersity index (PDI) of 0.184, formed the most stable system. This treatment significantly minimized weight loss (78.3%), retained the highest juice content (76%), and exhibited the lowest juice density (77.6%) compared to the control. It also effectively maintained vitamin C content (4.13 mg/g), titratable acidity (0.61 g/mL), and firmness. Additionally, the lowest electrolyte leakage and microbial load were observed in this treatment. The major components of marjoram essential oil were γ-terpinene (24.2%), o-cymene (20.1%), and carvacrol (16.9%), which played a key role in its antimicrobial and antioxidant activities. Sensory evaluation confirmed that the nanoemulsion preserved visual quality and flavor while preventing the damage caused by free essential oil. In conclusion, the use of *Plantago psyllium* mucilage nanoemulsion containing marjoram essential oil is proposed as an innovative and effective method to enhance the shelf life and maintain the quality of cherry tomatoes. This approach demonstrates significant potential for postharvest preservation while leveraging natural and sustainable technologies
Keywords: Electrolyte leakage, Nanoencapsulation, Perishability, Post-harvest quality, Shelf life
Extended Abstract
Introduction:
Cherry tomato is one of the most popular tomato varieties, widely appreciated for its small size, sweet flavor, and versatile use in salads, dishes, and as a food garnish. However, cherry tomatoes are highly perishable due to their high respiration rate and susceptibility to microbial and physical spoilage after harvest, leading to rapid quality deterioration. Therefore, developing effective methods to preserve quality and extend the storage life of this product is of great importance. In this regard, the use of edible coatings, natural antimicrobial compounds, and nanoemulsion technology can be considered as promising approaches. Recent advancements in nanotechnology have opened new possibilities for enhancing the efficacy of natural preservatives, particularly through improved stability and controlled release mechanisms.
Materials and Methods:
This study aimed to investigate the effects of Plantago psyllium mucilage, marjoram essential oil, and their nanoemulsion combination on the physicochemical, microbial, and sensory characteristics of cherry tomatoes during 28 days of storage at 4°C. Fruits were harvested at the physiological maturity stage. Following visual inspection and removal of defective specimens, uniformly sized and colored healthy fruits were selected based on strict criteria including absence of physical damage and uniform ripening stage. The fruits were washed with distilled water and surface-sanitized by immersion in sodium hypochlorite solution (2%) for one minute to eliminate surface microorganisms. For fungal inoculation, the tomatoes were immersed for one minute in a fungal spore suspension (10⁵ conidia/mL) of the most common postharvest pathogens, then left at room temperature for 1-2 hours to allow fungal establishment. Subsequently, the fruits were treated by immersion in respective treatment solutions for 90 seconds with gentle agitation to ensure complete coverage. Finally, the treated fruits were arranged in sterile plastic containers with proper ventilation and stored for 28 days in refrigerated conditions at 90% relative humidity, with periodic evaluations of their physicochemical properties at predetermined intervals (0, 7, 14, 21 and 28 days) using standardized analytical methods.
Results:
The results demonstrated that the simple effects of treatments, storage time, and their interaction had significant effects (at 1% and 5% probability levels) on most qualitative indices, including weight loss, juice density, firmness, titratable acidity, vitamin C content, electrolyte leakage, microbial load, and sensory evaluation. The Plantago psyllium mucilage nanoemulsion containing marjoram essential oil, with a particle size of 219.3 nm, zeta potential of -40.5 mV, and polydispersity index (PDI) of 0.184, formed the most stable system. This treatment significantly minimized weight loss (78.3%), retained the highest juice content (76%), and exhibited the lowest juice density (77.6%) compared to the control, indicating superior moisture retention properties. It also effectively maintained fruit firmness (85% higher than control), vitamin C content (4.13 mg/g), and titratable acidity (0.61 g/mL), suggesting slowed metabolic activity. Additionally, the lowest electrolyte leakage (67.2%) and microbial load (1.83 log CFU/g) were observed in this treatment, demonstrating membrane integrity preservation and antimicrobial efficacy. The major components of marjoram essential oil were γ-terpinene (24.2%), o-cymene (20.1%), and carvacrol (16.9%), which played a key role in its antimicrobial and antioxidant activities as confirmed by GC-MS analysis and in vitro assays. Sensory evaluation by a trained panel confirmed that the nanoemulsion preserved visual quality and flavor while preventing the damage caused by free essential oil, with significantly higher acceptability scores (p<0.05) for appearance, texture, and overall quality throughout the storage period.
Conclusion:
This study showed that using a nanoemulsion containing Plantago psyllium mucilage and marjoram essential oil significantly improved the quality and shelf-life of 'Azar' cherry tomatoes stored at 4°C. Nanoemulsion systems effectively protect active compounds and enhance targeted delivery, offering a sustainable alternative to traditional postharvest preservation methods. This approach helps reduce waste and maintain nutritional quality without synthetic additives. Future research should explore its application to other fruits, evaluate economic and production feasibility, and assess safety and regulatory issues. Overall, the findings highlight the potential of nanoemulsion technology to improve food preservation and support more sustainable agricultural practices.
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