نوع مقاله : مقالات پژوهشی
نویسندگان
1 گروه علوم باغبانی، دانشکده کشاورزی و منابع طبیعی، دانشگاه هرمزگان
2 هرمزگان
چکیده
نارنگی کینو، یکی از مهم‌ترین مرکبات کشت شده در کشور، پس از برداشت مستعد کاهش کیفیت به دلیل از دست دادن رطوبت و تغییرات فیزیولوژیکی است. حفظ کیفیت این میوه در طول دوره نگهداری، از جمله اهداف اصلی پژوهشگران می‌باشد. هدف از این پژوهش، بررسی تأثیر کاربرد قبل و بعد از برداشت ملاتونین بر کیفیت میوه نارنگی کینو در زمان برداشت و همچنین در مدت نگهداری در سردخانه می‌باشد. آزمایشی در قالب طرح بلوک‌های کامل تصادفی روی درختان 10 ساله نارنگی کینو در باغی واقع در شهرستان رودان انجام شد. محلول‌پاشی درختان با سه غلظت ملاتونین (صفر، 100 و 200 میکرومولار)، یک ماه قبل از برداشت به فاصله 7 روز یکبار تکرار شد. میوه‌ها در مرحله‌ی بلوغ تجاری برداشت و به دو گروه تقسیم شدند. گروه اول بلافاصله پس از برداشت از نظر ویژگی‌های مختلف فیزیکوشیمیایی مورد ارزیابی قرار گرفتند. گروه دوم به مدت 30 دقیقه در محلول ملاتونین (100 و 200 میکرومولار) غوطه‌ور شدند. سپس در دمای 5 درجه سانتی‌گراد به مدت 60 روز نگهداری شدند. ارزیابی خصوصیات کمی و کیفی میوه در روزهای 30 و 60 انبارمانی انجام شد. بر اساس نتایج به دست آمده، کاربرد قبل از برداشت ملاتونین نقش موثری در افزایش وزن میوه، وزن گوشت و حجم آب، اسید قابل تیتراسیون و محتوی آسکوربیکاسید میوه در زمان برداشت داشت. همچنین، محلول‌پاشی بطور معنی‌داری باعث افزایش محتوی آسکوربیکاسید، فنل، فلاونوئید و ظرفیت آنتی‌اکسیدانی میوه گردید. در پایان انبارمانی، میوه‌های تیمار شده نسبت به شاهد کاهش وزن کمتری نشان دادند. بطوریکه حداقل کاهش وزن در میوه‌های محلول‌پاشی شده با ملاتونین 200 میکرومولار و میوه‌های غوطه‌ور شده پس ازبرداشت در ملاتونین 200 میکرومولار مشاهده شد. همچنین میوه‌های تیمار شده محتوی آسکوربیکاسید و فلاونوئید بالاتری نسبت به شاهد نشان دادند. در روز 60 انبارمانی، بیشترین ظرفیت انتی‌اکسیدانی در میوه‌های محلول‌پاشی شده با غلظت 100 میکرومولار مشاهده شد. بطور کلی در ارزیابی بازارپسندی و خصوصیات ظاهری میوه، تیمارهای محلول‌پاشی شده وضعیت بهتری نسبت به سایر تیمارها نشان دادند.
کلیدواژه‌ها
موضوعات
عنوان مقاله [English]
Improving the quality and shelf life of Kinnow mandarin fruits using pre- and post-harvest melatonin treatments
نویسندگان [English]
- Sakineh Molaei Mohammad Abadi 1
- somayeh rastegar 2
1 Horticultural Sciences, Department of Horticultural Sciences, Faculty of Agriculture and Natural Resources, University of Hormozgan, Bandar Abbas, Iran.
2 University of Hormozgan
چکیده [English]
Introduction
Kinnow mandarin is one of the most important citrus fruits that undergoes significant postharvest quality deterioration. This deterioration is primarily due to moisture loss, physiological changes, and pathogen infections. To maintain the quality and extend the shelf-life of kinnow mandarins, various postharvest treatments and storage conditions have been explored. Melatonin, being a nontoxic and safe chemical, has application potential in the improvement of fruit quality. By stimulating the production of antioxidants like ascorbic acid and phenolics, melatonin can boost the overall antioxidant capacity of fruits. It has been reported that by influencing pigment production, melatonin can enhance fruit color and appearance. Further research is needed to optimize the application methods and determine the most effective melatonin concentrations for different cultivars and storage conditions. Additionally, the underlying physiological and biochemical mechanisms by which melatonin enhances fruit quality during postharvest storage warrant further investigation. Implementing melatonin treatments in commercial postharvest operations could provide a valuable strategy for maintaining the quality and extending the shelf-life of Kinnow mandarins and other citrus fruits.
Materials and Methods
A field experiment was conducted in a citrus orchard located in Rudkhan district, Rudan county, Iran. Ten-year-old Kinnow mandarin (Citrus nobilis × Citrus deliciosa) trees were treated with three melatonin concentrations: 0 µM (distilled water as control), 100 µM, and 200 µM. The treatments were applied as foliar sprays one month prior to harvest, repeated three times at weekly intervals. Mature fruits were harvested in December and randomly divided into two groups: one for immediate analysis and the other for storage. Fruits destined for storage were disinfected with 0.05% sodium hypochlorite for one min, rinsed with distilled water, and then subjected to a 30-min soak in melatonin solutions (100 µM or 200 µM) corresponding to the previous foliar treatment. The fruits were then stored at 5 ± 1°C. Samples were evaluated for physicochemical properties at 30 and 60 days of storage. A factorial experiment was conducted in a randomized complete block design. Data were analyzed using SAS software, version 9.4. Means were compared using the Least Significant Difference (LSD) test at the 5% level of significance. Graphs were generated using Excel software.
Results and Discussion
The results showed that melatonin treatments significantly increased fruit weight, pulp weight, juice volume, titratable acidity, and ascorbic acid content at harvest. During storage, both sprayed and immersed fruits exhibited less weight loss. At the end of the storage period, treated fruits also had higher ascorbic acid content compared to the control. Fruit immersion was more effective in preserving total flavonoids at the end of the experiment. The highest antioxidant capacity was observed in fruits sprayed with 100 μM melatonin. Melatonin is a potent antioxidant, scavenging free radicals and protecting cellular components from oxidative damage. In addition, by modulating ethylene production, melatonin can influence fruit ripening rate and overall quality. Melatonin has been studied in fruits like mango and papaya, where it has shown potential to improve fruit quality and extend shelf life. Studies on citrus fruits have indicated that melatonin can reduce chilling injury, maintain juice quality, and increase antioxidant content. It's important to note that the optimal melatonin concentration and application method can vary significantly between fruit species. Overall, the sprayed treatments showed better performance in terms of marketability and various quality attributes compared to the other treatments. The findings of this study suggest that pre- and post-harvest melatonin treatments can effectively maintain the quality and extend the shelf-life of Kinnow mandarin fruit during cold storage. Melatonin's antioxidant properties and ability to regulate physiological processes may contribute to the observed improvements in fruit quality. These results have important implications for the postharvest management of Kinnow mandarins, as melatonin could be a valuable tool for preserving the fruit's nutritional and sensory attributes during storage and transportation.
Conclusions
The results of this study demonstrate that melatonin application had a beneficial impact on Kinnow mandarin fruits. Overall, the melatonin spray treatment, particularly at a concentration of 100 µM, led to increased fruit weight, water content, ascorbic acid content, and titratable acidity at harvest. During storage, treated fruits exhibited higher antioxidant capacity, phenolic and flavonoid content, and ascorbic acid levels, along with reduced weight loss compared to the control group. Consequently, the use of melatonin is proposed as a promising strategy to enhance the quality and marketability of Kinnow mandarins during postharvest storage.
کلیدواژه‌ها [English]
- Ascorbic acid
- antioxidant capacity
- quality
- spray
- citrus
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