Effect of galbanum gum coating combined with cumin essential oil and calcium chloride on quality and shelf life of sweet cherry (cv. Siah Mashhad)

Galbanum, an aromatic oleo-resin gum, is produced from umbelliferous Persian plant species in the genus Ferula with the common Persian name “Barije”, chiefly endemic flora of the mountain ranges of northern Iran. Cuminum cyminum is an edible medicinal plant, which is widely distributed in Iran, Turkey, India, Egypt and Central America countries. Calcium (Ca2+) is a secondary messenger that plays pivotal roles (such as cell wall structure, signaling in fruit ripening and ethylene biosynthesis) in regulating physiological functions in fruits, vegetables and flowers during postharvest life. Sweet cherry is one of the most popular fruits among consumers because of its good taste and abundant nutrients and bioactive components such as phenolic compounds and flavonoids. This fruit is a highly perishable product due to its high respiration rate and rapid softening process at room temperature, which ultimately cause the color changes, weight loss, browning and changes of nutrients and restrict its shelf life. Several studies have demonstrated that the postharvest life of sweet cherries can be extended by different preservation techniques, such as refrigeration, synthetic chemical fungicides, modified atmosphere packaging, osmotic treatments, hypobaric treatments, heat treatments and edible coating. In the last several years, edible coatings have been widely studied for the preservation of fruits and vegetables. Edible coating with semipermeable films might extend the postharvest life of sweet cherry through a reduction of moisture migration, gas exchange, respiration and oxidative reaction rates. Healthy fruits, uniform in size, shape, color, and degree of maturity were selected from sweet cherries collected from orchard in Kahriz located in Urmia. Effects of galbanum gum (0, 1, 2 and 3% W/V), cumin essential oil (0, 100 and 200 µl/l) and calcium chloride (0 and 1% W/V) coating on the physiological and quality responses of sweet cherry (Prunus avium Cv. Siah Mashhad) fruit were investigated. The fruits were coated, and stored at 2±1 ºC and 90-95% relative humidity for 30 day and then transferred to 20 ºC for an additional 1 day. The quality of sweet cherries was analyzed at the initial day, 15-day after storage in 2±1 ºC and 30-day after storage in 2±1 ºC+ an additional 1 day in 20 ºC. Different qualitative and physicochemical attributes including pH, total soluble solid, titrable acidity, fruit water content and moisture percentage, proline, malondialdehyde, phenyl alanine amonialyase (PAL) enzyme activity and nutraceutical (total phenol and flavonoid) evaluations were performed. Statistical analysis of data was done by SAS (version 9.4) and mean comparisons were performed using Duncan's multiple range test. Significant differences were observed in fruit coated galbanum gum 1% W/V, cumin essential oil 200 µl/l and calcium chloride 1% W/V as compared to the control. The coating applications including gum, cumin essence and calcium chloride resulted in slower rise of pH and TSS, and were effective in maintaining higher titrable acidity, fruit water content, moisture percentage, PAL enzyme activity, total phenol and flavonoid. Coating with 1% W/V galbanum gum combined with 1% W/V calcium chloride resulted in highest increase of PAL enzyme activity and total phenol 15-day after storage, which effectively prevented rapid decline enzyme activity and phenolic compound to the end of storage. The combined coating of galbanum gum 2% W/V with CaCl2 1% W/V or 200 µl/l cumin essential oil significantly maintained total flavonoid 30-day after storage in 2±1 ºC + an additional 1 day in 20ºC; These treatment are not significantly different with galbanum gum 1% W/V with CaCl2 1% W/V or 200 µl/l cumin essential oil. Concomitantly proline content (0.002748 mgr/gr F.W.) was at higher levels and malondialdehyde (0.0320 mmol/gr F.W.) at lower levels in tissues of treated fruit with 1% W/V CaCl2 compared with those of control fruit at the end of storage. Fruit and vegetables are highly perishable, and the causes of postharvest losses can generally be ascribed to physiological deterioration associated with consumption of the internal water and reserve substances. In addition, increasing public concern towards healthy foods has contributed to the promotion of interest in the development of alternative (Safe) methods for controlling postharvest decay and deterioration. These results suggest that galbanum gum, cumin essence and CaCl2 treatments delayed the development of senescence process ‘Siah mashhad’ sweet cherry by delaying the loss of quality parameters, polyphenol substances and maintaining the structural integrity of cell membrane. Application of 1% W/V galbanum gum coating combined with 1% W/V CaCl2 might be enhanced low temperature tolerance by maintaining quality parameters, antioxidant compound and shelf life of sweet cherry fruits.