با همکاری انجمن علمی منظر ایران
نوع مقاله : مقالات پژوهشی
نویسندگان
گروه باغبانی، دانشکده کشاورزی، دانشگاه ارومیه، ارومیه، ایران
کلیدواژهها
عنوان مقاله English
نویسندگان English
Introduction: Date palm fruit (Phoenix dactylifera L.) is a rich and important source of energy and nutrients. Maktoom variety known for the soft, large and flavorful characteristics of fruit. Rutab is considered as fresh fruit and the choice for harvesting at which maturity stage depends on the cultivar, soluble tannins and sugar contents, and meanwhile considering the climate conditions and consumer demands. Sugar content not only is important for sweetness of the fruits, but also changes in sugars content could have significant effects on physiological features and ripening of date palms. Postharvest losses in fresh dates including Maktoom variety are mainly caused by biological factors and biochemical changes caused by enzymes activity, respiration, ethylene action, water loss and oxidation process, and mechanical damages. Recently, global concern about food safety related to the use of chemical preservatives have increased. Consequently, there is a need to explore and implement novel, safe and sustainable methods. Use of nanotechnology and edible coatings are considered as efficient technologies being explored to mitigate the postharvest losses of horticultural crops. Chitosan nanoparticles, derived from natural chitin sources, are prominent due to their biodegradability, non-toxicity, and antimicrobial properties. Chitosan coating is regarded the best edible and biologically safe preservation coating for many types of fruits, with functional benefits such as slower respiration, extended storage time, fruit shelf life, firmness retention, and microbial pathogen management. This study was conducted to investigate the efficacy of post-harvest application of nanochitosan nanoparticles on preserving postharvest quality and to enhance the shelf life of Maktoom date palm fruit harvested at rutab stage during storage at refrigerator conditions. These methods at the same time are able to extend the shelf life, ensure food safety, and preserve the nutritional and sensory qualities of the date palm fruits. The study focuses on quantifying changes in sugar composition, invertase and cellulase enzymes activities, secondary metabolite contents and antioxidant activity of Maktoon date palm fruits.
Material and Methods: The experiment was conducted at Qurna College, Qurna city, the north of Basrah, Iraq. Maktoom date palm fruits were harvested at rutab stage, characterized by a yellow color, chosen for uniformity in size, shape, and color, while any flawed or decayed fruits were eliminated. The fruits were allocated at random into 35 fruits in each group. Nanochitosan (Crab20 shell chitosan, Sigma Chemicals) at 0, 0.5, 1, 1.5 and 2% concentrations were prepared in distilled water. In order to dissolve the chitosan glacial acetic acid was first added and 1 mol L-1 NaOH was used for adjusting the pH of the solution to 5.0. Treated fruit were dried for 30 min at 25°C, placed in polyethylene vacuum bags (35 fruits in each replicate) and stored for 45 days at 2±1°C with the relative humidity of 90%. Each treatment was consisted of tree replicates. For control treatment the fruits were dipped in control acid solution, pH 5.0, without chitosan. The experiment was performed as a completely randomized (CRD) design in three replicates. The difference between the means was tested using Duncan’s multiple range test at significance level of 1 % and 5 % with SAS 9.1 software.
Results and Discussion: Fruit ripening and senescence include the activation of different degrading enzymes, reactive oxygen species (ROS) and free radical overproduction which leading to the destruction of cell walls, increase in total soluble solids, soluble sugars and decrease in total acids and firmness. In this research, the results showed that postharvest application of nanochitosan eliminated total soluble solids, total sugars and reducing sugars content of rutab date palm fruit. The lowest total soluble solids content (28.08 Brix), total sugars (43.33 %) and reducing sugars (30.56 %) content was measured in 1% nanochitosan samples. Also nanochitosan reduced hydrolyzing enzymes activities and the lowest invetase and cellulase enzymes activities was assayed in 1% nanochitosan samples which was 30.06% and 36.45% lower than control one (0% nanochitosan), respectively. Reduction in invertase enzyme activity in response to nanochitosan led to a decline in reducing sugars and an increase in sucrose content. The highest total acidity, total phenolic content and total antioxidant activity was measured in rutab date palm fruits treated with 1% nanochitosan, which was 19.34%, 11.10% and 18.74% higher than control. Chitosan coatings enhanced antioxidant levels by increasing secondary metabolites like phenolic compounds. These effects collectively improve the fruit quality, the extend shelf life, and maintain nutritional and biochemical properties of fruits. Also, total free amino acids content of fruits increased in response to different concentrations of nanochitosan and the highest total free amino acids (50. 66 mg 100g-1 FW) was measured in date fruits treated with 1% nanochitosan.
Conclusion: Rutab fruit is highly consumed product with high economic and nutritional value. The findings of this study indicate that postharvest application of nanochitosan is an effective method to reduce metabolic activities, maintain quality, and increase the shelf life of rutabs by influenceing soluble sugars profile, acidity content, the activity of degrading enzymes, and increasing antioxidant compounds. In sum, nanochitosan 1%, in conjunction with polyethylene vacuum packaging offers an effective and eco-friendly approach to maintain the postharvest quality of rutab fruits.
کلیدواژهها English
