Citronella essential oil on post-harvest quality and shelf life of mango
Citronella essential oil on post-harvest quality and shelf life of mango
Citronella oil emulsion on shelf life and quality of ambient stored mango cv. Rangkuai. Citronella oil (Cymbopogon nardus) @ 0.5% (v/v) was found to maintain low weight loss, high fruit firmness, ascorbic acid, total phenol and least fruit decay at 12 days after storage (DAS) and had delayed accumulation of pulp colour, β-carotene and total sugar for delayed ripening, thus found to extend the shelf life by 7 days compared with control.
Materials and Methods
Freshly harvested, uniform shape, size, colour, firmness, pest, disease and injury free mature green mango cv. Rangkuai fruits were collected from local mango growers. Dust and dirt were removed by thoroughly washing the fruits under running tap water and surface sterilized with ethanol (70% v/v), quick dipping for 30 sec followed by rinsing in double distilled water. Fruits were kept under a stream of dehumidified air for 10 min. Five fruits were kept in ventilated paper box under each replication and replicated four times under ten post-harvest treatment Citronella (Cymbopogon nardus) oil, and kept at ambient condition (Temperature: 20 ± 3 0C; Relative humidity: 70 ± 5%). The 100% pure, hydro-distilled essential oils of Citronella (leaves and stems), was used for preparation of treatments. Respective essential oil (EO) coating was prepared by mixing EO (0.5% v/v) with Glycerol (1.2% v/v) and Coconut oil (80% v/v) along with sterile water. All formulations were mixed in homogenizer for 5 minutes at 24,500 rpm to form the emulsion for coating by dipping the fruits for 2 minutes. Observations on physiological weight loss (using digital balance), fruit firmness (using digital Penetrometer), and biochemical parameters viz. total soluble solids (TSS; using handheld refractometer), total carbohydrates, protein, total phenol and β-carotene were determined as per method described by Sadasivam and Manickam. Total sugar, titratable acidity and ascorbic acid content (AOAC 2012) were recorded at 4, 8 and 12 days at storage (DAS) whereas, fruit flesh colour (using Digital Colour Meter for L* ,a* ,b* ), antioxidant activityand fruit decay were determined at 12 DAS. Shelf life (days) was evaluated depending on the fruit decay, fruit physico – chemical parameters and counting the days from harvest to the day with maximum visual, edible and marketable quality.
Results
Physiological weight loss (PWL) of mango fruits increased consistently during ambient storage because of loss in moisture due to transpiration, respiration along with metabolic uses. It ranged between 1.56 and 8.82 % at 4 DAS, and ranged between 3.25 and 12.12% at 10 DAS. At 12 DAS, minimum PWL (5.14%) was found in Citronella oil treated fruits compared with control (18.92%). Consequently, loss of surface moisture from stored mango caused significant reduction in fruit firmness, however, fruits treated with Citronella oil (T2) had reasonably high firmness (52.85 N/cm2 ) compared with control (28.31 N/cm2 ) at 12 DAS. Citronella oil emulsified coating might have reduced the surface moisture loss and maintained the fruit firmness. Skin colour of mango cv. Rangkuai remained intense green even at ripening, but the flesh colour changed to orange yellow (L: 59.22, a: 34.91, b: 48.00) in control compared with fruits treated with Citronella oil (whitish yellow, L: 91.06, a: -2.61, b: 24.03 ) at 12 DAS. Total carbohydrate which was high (14.23-14.83% at 4DAS) initially, reduced (10.89-11.56% at 12 DAS) subsequently because of amylase hydrolysis of starch and resulted in significant increase in total sugar content of stored mango across the treatments. At 12 DAS, total sugar content of mango was maximum in control (8.78 %) followed by coconut oil treated (8.12%) compared with citronella oil treated (4.46%) fruits. Enhanced respiration of climacteric mango caused enzymatic conversion of starch to sugar and manifested as increased sugar accumulation in control fruits compared with essential oil treated fruits. Post-harvest ripening of mango caused accumulation in total soluble solids (TSS) with reduction in titrable acidity and resulted in increment of TSS:acid ratio. Thus, faster ripened control mangoes had maximum TSS : acid ratio (32.71) compared with delay ripened citronella oil treated fruits (6.81) at 12 DAS. In present study ascorbic acid which ranged between 28.79 and 41.23 mg/100 g at 4 DAS got reduced and ranged between 18.35 and 33.62 mg/100 g at 12 DAS. Maximum retention of ascorbic acid was found in citronella oil treated (33.62 mg/100 g) mangoes fruits at 12 DAS. Protein and total phenol content of mango fruits decreased during storage. However, fruits treated with citronella and basil oil was found to retain more protein (0.51, 0.45%) and total phenol (89.67, 88.51 mg/100 g) compared with control (0.32% protein and 70.99 mg/100 g total phenol) at 12 DAS. Further, DPPH radical scavenging activity (antioxidant assay) was recorded high in citronella (71.48 ± 1.02 %) treated mango fruits compared with control (23.46 ± 0.85 %) at 12 DAS. At 12 DAS, citronella oil treated mangoes had least fruit decay (8.33%) compared with control (44.67%). Maximum shelf life (19.17 days) was recorded in Citronella oil coated mangoes compared with control (12.85 days). Protective barrier for inhibiting moisture loss, reduced respiration may have resulted in delayed ripening and maintenance of fruit quality, while antimicrobial effect controlled the fruit decay and finally resulted in higher shelf life in mangoes coated with citronella oil emulsion.
It concluded that post-harvest coating with citronella oil emulsion (0.5% v/v) can be a suitable method for controlling post-harvest diseases, retaining fruit quality and extending shelf life in mangoes stored at ambient condition.
Reference:
Mandal, D. and Mualchin, M., 2021. Effects of Essential Oils on Post Harvest Quality and Shelf Life of Mango (Mangifera Indica L.). Bangladesh Journal of Botany, 50(4), pp.1143-1149.
