| Abstract |
The present investigation, entitled "Fruit development studies and postharvest management of dragon fruit (Hylocereus costaricensis)," was conducted at the Department of Postharvest Management, College of Agriculture, Vellayani, Kerala Agricultural University, during 2022-2025, with the objectives to study fruit growth during development and maturation phases, standardisation of efficient postharvest treatments to extend shelf life, and development an efficient packaging, storage, and transportation system for purplish-red dragon fruit (H. costaricensis). Fruit growth and maturation studies were conducted from the 10th to the 32nd day after anthesis by tagging flowers on the day of anthesis and harvesting fruits at different developmental stages. Physicochemical observations revealed distinct developmental patterns in H. costaricensis fruits from anthesis to maturity. Fruit weight, length, and diameter increased steadily, with sphericity approaching 100% by 31st day of anthesis. Moisture content and total flavonoids decreased progressively throughout storage, accompanied by a corresponding rise in pulp percentage and total soluble solids. The sugar : acid ratio peaked (41.90) on day 29, coinciding with maximum levels of ascorbic acid and carotenoids. The peel colour transitioned from green to reddish-purple, and the pulp colour transitioned from creamy white to reddishpurple during the development. Sensory parameters increased steadily from the 25th day, with appearance, texture, and taste scores peaking on the 29th day. Detailed biochemical profiling identified fourteen sugars, eleven organic acids, eighteen phenols, and fifteen flavonoids across developmental stages, with fructose (1,159.79 μg g⁻¹), malic acid (857.53 μg g⁻¹), ferulic acid (5.13 μg GAE g⁻¹), and apigenin (70.77 ng g⁻¹) as the predominant compounds at the 29th day after anthesis. Based on the comprehensive evaluation of physicochemical and sensory quality attributes throughout the developmental stages, the 29th day after anthesis was identified as the optimal harvest maturity for H. costaricensis grown under humid tropical climate. At this stage, fruits recorded an ideal sugar: acid ratio of 41.9, full peel and pulp colour development, and a shelf life of 4 days. Optimum physicochemical characteristics including fruit weight (348.23 g), pulp percentage (71.80%), firmness (0.54 N), TSS (15.60°Brix), total sugars (11.23%), and reducing sugars (4.55%), along with the highest values for ascorbic acid (104.0 mg 100 g⁻¹) and carotenoids (204.92 μg 100 g⁻¹), and maximum sensory scores for taste (8.73), texture (8.13), and overall acceptability (8.41) were also recorded at this stage. The number of days from anthesis, attainment of full peel colour, and fruit sphericity (>95%) were identified as practical and reliable indicators for determining the precise harvest timing of dragon fruit. The postharvest treatment studies of purplish red dragon fruit were conducted with different concentrations of chitosan (1%, 2%, 3%), salicylic acid (0.5 mM, 1.0 mM, 2.0 mM), and aloe gel (5%, 10%, 15%) to optimise effective postharvest treatment. The fruits at optimum maturity (29th day after anthesis) were ozonised (2 ppm), subjected to various postharvest treatments, packed in CFB boxes, and stored at room temperature (27±2°C) until the end of shelf life. The studies revealed significant concentration dependent differences among treatments in minimizing storage induced deterioration. Among the different concentrations of chitosan studied, the treatment with 1% chitosan demonstrated superior performance with minimum PLW (4.78%), maximum firmness (0.63 N), highest marketability (75.00%), and extended shelf life of 6 days, along with the highest retention of biochemical constituents. Among salicylic acid treatments, 0.5 mM salicylic acid demonstrated the most pronounced effect, with minimum PLW (4.92%), highest marketability (82.50%), and maximum retention of firmness (0.45 N), ascorbic acid (93.15 mg 100g⁻¹), total phenols (70.25 mg GAE 100g⁻¹), flavonoids (39.02 µg QUE 100g⁻¹), carotenoids (205.18 µg 100g⁻¹), and betalains (69.01 mg BE 100g⁻¹), extending shelf life to 8 days. Among aloe gel treatments, 10% aloe gel showed optimal results with minimum PLW (4.15%), maximum firmness (0.52 N), highest marketability (87.50%), and excellent retention of bioactive compounds and sensory quality, extending the shelf life to 7 days. Hence, based on a comprehensive evaluation of all quality parameters across the different concentrations of postharvest treatments, 1% chitosan, 0.5 mM salicylic acid, and 10% aloe gel were selected as postharvest treatments for subsequent storage studies. For the storage studies, fruits harvested at optimum maturity stage (29th day after anthesis) were subjected to the selected best postharvest treatments viz., 1% chitosan, 0.5 mM salicylic acid, and 10% aloe gel. After treatment, fruits were air dried, packed in CFB boxes, and stored at room temperature (27 ± 2°C) and refrigerated conditions (10 ± 1°C) were analysed for physiological, physicochemical, and sensory parameters were analysed periodically. The results revealed that, under both storage conditions, 0.5 mM salicylic acid treatment recorded the longest shelf life and retained the maximum quality, and its performance was further enhanced under refrigeration. Under room temperature, salicylic acid extended shelf life to 8 days compared to 4.25 days in untreated fruits, recording the minimum PLW (4.73%), the maximum firmness (0.45 N), highest marketability (82.50%), and the maximum retention of TSS (16.10°Brix), ascorbic acid (92.12 mg 100g⁻¹), phenols (70.76 mg GAE 100g⁻¹), flavonoids (39.33 μg QUE 100g⁻¹), antioxidant activity (49.22%), carotenoids (205.13 µg 100g⁻¹), and betalains (69.98 mg BE 100g⁻¹), with the highest sensory scores. Under refrigeration, the 0.5 mM salicylic acid treatment extended shelf life to 24 days compared to untreated controls (15 days) and maintained minimal PLW (5.40%), maximum firmness (0.45 N), highest marketability (83.75%), and retained maximum total phenols (70.18 mg GAE 100g⁻¹), total flavonoids (35.81 µg QUE 100g⁻¹), antioxidant activity (49.57%), carotenoids (205.13 μg 100g⁻¹), and betalain (46.70 mg BE 100g⁻¹), and sensory quality throughout storage. Packaging studies were conducted to identify the most efficient packaging and storage system to extend the shelf life of dragon fruit. Salicylic acid (0.5 mM) treated fruits (harvested on the 29th day after anthesis) were subjected to different prepackaging treatments, viz., shrink packaging, LDPE packaging (2% ventilation), Polypropylene (PP) packaging (2% ventilation), and control without packaging and were stored in CFB boxes under room temperature (27±2°C) and refrigerated conditions (10±1°C) until the end of their shelf life. The effect of each packaging was evaluated in comparison with an absolute control (fruit without salicylic acid treatment and without packaging), based on physical, physiological, biochemical, and sensory parameters during storage. The results revealed that PP packaging proved more effective than all other treatments under both storage conditions, extending shelf life to 9 days at room temperature (27 ± 2°C) and to 27 days under refrigeration (10 ± 1°C), whereas the untreated and packaged fruits recorded a shelf life of 4 days and 15 days, respectively. PP packaging also retained better physicochemical and sensory quality attributes were also recorded for PP packaging. Under room temperature, the fruits maintained 80% marketability, 16.30°Brix TSS, 1refrigeration, the fruits recorded 83.33% marketability, 16.27°Brix TSS, 11.30% total sugars, and 96.95 mg 100 g⁻¹ ascorbic acid. Hence, Polypropylene (PP) packaging was identified as the most effective packaging for maintaining the physicochemical and sensory quality of dragon fruit under both storage conditions. Transportation studies were conducted to assess the efficiency of different fruit arrangements during the commercial distribution of dragon fruit. The fruits were arranged vertically with bracts facing upwards, horizontally with bracts facing the center, and without any specific arrangement (control), in CFB boxes with cushioning material (white paper bubble wrap), and were then transported over 100 km to simulate typical commercial distribution conditions. The fruits arranged vertically with bracts facing upwards retained the highest post-transport and storage quality with minimum PLW (1.70%), lowest physical damage (8.53%), longest shelf life (8.33 days), and highest sensory scores. Hence, vertically arranged fruits with bracts facing upwards, packed in CFB boxes with cushioning materials, were identified as the most efficient fruit arrangement for bulk packaging and transportation of dragon fruit. Fruit development studies and postharvest management of purplish-red dragon fruit (H. costaricensis) (cv. Malaysian Red) successfully established optimal harvest maturity at 29 days after anthesis and demonstrated that 0.5 mM salicylic acid treatment as the most effective postharvest treatment for extending the shelf life of dragon fruit to 8 days under room temperature storage and to 24 days under refrigeration storage conditions. Polypropylene (PP) packaging in combination with 0.5 mM salicylic acid treatment was identified as efficient packaging, for dragon fruit, and it further prolonged storage life to 9 days under room temperature storage and to 27 days under refrigerated conditions. The vertical placement of fruits with bracts facing upwards, cushioned with white paper bubble wrap in CFB boxes, was identified as an ideal fruit arrangement for minimising physical injuries and preserving post transport quality of the fruits during commercial transportation. This scientifically validated and standardized protocol provides a commercially viable, comprehensive postharvest management system for purplish-red dragon fruit, encompassing all stages from harvest maturity determination to storage and distribution1.13% total sugars, and 96.97 mg 100 g⁻¹ ascorbic acid, and under |
