Bayogan E.V., Morales W.L.A, Secretaria L.B., Franco R.K.G., Palenzuela M.J.B., Urquiola M.A.J. December, 2023 . Introduction Mango (Mangifera indica L.) is a tropical fruit with a unique flavor and high nutritional benefits. It is considered the most important fruit crop in the country based on its high export volume and value, next to banana and pineapple (Department of Agriculture, 2013). The 'Carabao' mango, also known as the 'Super Manila' mango, is a popular variety in the international market. Over the years, there has been an increase in demand for mangoes. However, the Philippines is facing challenges in consistently delivering high quality mangoes to major markets. These challenges are due to various factors such as pests, diseases, poor pre- and post-harvest management, and gaps in the supply chain (PCAARRD-DOST, 2019). Despite the availability of some technologies to reduce production problems in mango, technology adoption remains low. Various technologies, including hot water treatment (HWT), have been studied to improve the quality of mangoes. HWT is a postharvest treatment to control important postharvest diseases such as anthracnose and stem end (Mansour et al., 2006; Le et al., 2010). Heat treatments (HWT 52-55°C, 5 min; and rapid HWT 59-60°C, 35-60 sec) in ‘Carabao’ mango controlled the incidence of anthracnose and stem end rot (Pasilan et al., 2020; Esguerra, 2006). Despite the benefits of HWT, adoption of the technology in the country is very limited to fresh fruit exporters and processors. (Esguerra et al., 2006). An in-transit handling trial was conducted to gain a better understanding of the conditions and quality of mangoes along the local supply chain with the use of hot water treatment. This study monitored the conditions and assessed the quality of mangoes during transit. Materials and Methods Mangoes were harvested from a farm in the Island Garden City of Samal, Davao del Norte. Fruit was harvested at 110 days after flower induction (DAFI). An actual in-trial for the domestic market in Manila was conducted using a wing van to follow the local supply chain from Mindanao to Luzon. (Figure 2). The mangoes were transported from Davao City to Camona City in Cavite then to Los Banos, Laguna in Luzon for a duration of four days. Mangoes were harvested from a contracted farm in Samal Island. Mango samples were delivered to the Postharvest Laboratory at the University of the Philippines Mindanao (UP Mindanao) for hot water treatment, quality evaluation and packing of fruit. Fruit samples were subjected to hot water treatment at 52-55°C for 5 min while untreated fruit served as control. Fruit was packed in newspaper-lined carton boxes at 20kg per box and delivered to a trucking service in Digos City (49.5 km from UP Mindanao, Davao City). Three boxes of untreated and heat-treated fruit were loaded and positioned individually at different positions (i.e. top, middle and bottom) of the forward truck for delivery to Cavite. . Temperature and relative humidity inside the boxes during transit were monitored using Elitech GSP-6 Temperature and Humidity Data Loggers. The supply chain of mango from Davao City to Cavite City was followed. The shipment of the cargo via land took four days from Digos City to Carmona City (40 km from Manila). Fruit was transported next to the Postharvest Horticulture Training and Research Center at the University of the Philippines Los Banos, Laguna (38.9 km from Carmona City). Figure 1: Postharvest handling of ‘Carabao’ mango along the supply chain from UP Mindanao to UP Los Baños The mango fruit were assessed for bruise (damage by nails, ‘kaing’ or bamboo basket damage during harvest and peduncle punctures of other mangoes) and compression (during transport) damage before storage. Damage-free fruit were selected and stored at ambient (28.7 ± 1.8 °C, 71.2 ± 6.2% relative humidity). Sixteen (16) fruit were used for each . of the three replicates per treatment: 10 fruit as non-destructive samples and 6 fruit as destructive samples each of the five sampling times. The treatments were HWT and no HWT as Factor A, while Factor B was the stack position of the boxes - top, middle, and bottom layer. Ripening changes were monitored based on: • Peel yellowing using peel color index 1-6 (1 = green; 2 = breaker, trace of yellow at stem-end; 3 = turning, more green than yellow; 4 = more yellow than green; 5 = yellow with trace of green; and 6 = fully yellow) • Minolta CR-400 Chromameter taking the 𝐿∗, 𝑎∗, and 𝑏∗ coordinates • Fruit softening using firmness tester • Respiration (CO2 production) and ethylene production using Shimadzu gas chromatograph with thermal conductivity and flame ionization detector, respectively • Total soluble solids (TSS) using a digital refractometer • Titratable acidity (TA) by titration against a standard base and pH using a digital pH meter; • Antioxidant content in terms of vitamin C, total phenolics, and DPPH activity. Six fruits were used to measure respiration rate and ethylene production wherein the fruits were sealed individually in jars for one hour. Shelf life attributes were measured, other than ripening, which included weight loss expressed as percentage of the initial weight; shriveling using a rating scale of 1-5 (1 = none, 2 = slight, 3 = moderate, 4 =severe and 5 = extremely severe symptoms of shriveling); disease incidence (anthracnose and stem end rot) using a 6-point scale (1 = none, 2 = 5% infection, 3 = 10% infection, 4 = 11-25% infection, 5 = 26-50% infection, and 6 = more than 51% infection); and visual quality using a 9-point rating scale (9 = excellent, no defect, 7 = good, defects minor, 5 = fair, defects moderate, 3 = limit of marketability, 2 = limit of edibility, and 1 = non-edible). A completely randomized design was used. Results were analyzed by performing analysis of variance (ANOVA) using SAS On Demand statistical software. . Results Supply chain of mangoes from the Davao Region Mangoes sourced from the Davao Region and other areas in Mindanao are supplied to the National Capital Region (NCR), particularly during the lean season from July to December (Figure 2). Mindanao growers can produce mangoes all year round due to flowering induction, which allows for more trade opportunities in Manila. Figure 2: Supply chain of ‘Carabao’ mango from Davao Region in Mindanao to Carmona City in Luzon. Mangoes are transported to Manila via land-based trucking and air cargo services. The assembler-wholesalers are the primary traders of these mangoes, while other buyers include retailer-processors. Most of the suppliers from Mindanao assemble the mangoes through a trucking service to bring their mangoes to the National Capital Region (NCR), particularly in Carmona City in Cavite where the products are unloaded and picked up by the wholesalers. Some also deliver to the Eastern Visayas and Bicol Regions while others deliver directly to a fruit processing plant that exports mostly dried mangoes to the U.S.A. and is also located in Cavite (Shuck et al., 2023). Major wholesale markets in Manila include the Nepa-Q Mart and Divisoria. Mango retailers, such as vendors, from fruit stands and vendors to online sellers and supermarkets, source from the major public markets (Shuck et al., 2023). Temperature and relative humidity The temperature and relative humidity logs were recorded over the entire duration of the trip at different positions during in-transit. An average temperature of 29.21°C and relative humidity of 92.96% were recorded inside mango boxes throughout transit (Figure 3). Mango boxes positioned at the bottom showed a higher mean temperature of 29.73°C. . Boxes positioned at the top were 1.12°C lower temperature compared to boxes placed at the bottom. The mango boxes positioned in the middle registered a lower relative humidity of 90.37%, which was 4% lower than those placed at the top and bottom. Figure 3: Temperature and relative humidity inside mango boxes during in-transit from Davao City to Carmon City. Handling damage Compression and bruises were the handling damages observed. Compression damage was highest in hot water (HW)-treated mangoes regardless of the stacking position (top, middle, and bottom layers) of the boxes during transportation (Table 1). For control fruit, compression damage was observed only on fruit from top-layer boxes. Bruises were noted on fruit positioned at the middle layer of the stack for the unheated fruit and from the bottom layer of the stack for HW-treated fruit. The results suggest no direct relationship between stacking position and physical damage during transport. HWT seemed to predispose fruit to compression damage. However, it should be noted that the sample cartons had been carefully packed by UP Mindanao researchers whereas commercial cartons tend to be more overpacked so could suffer more bruising than was observed in this trial. . Table 1: Handling defects (% of total fruit samples) of ‘Carabao’ mangoes transported from Davao City to Carmona City and assessed at Postharvest Horticulture Training and Research Center, Laguna. Stack layer during transport Compression Bruise HWT Control HWT Control Top 6.7 13.3 0.0 0.0 Middle 16.7 0.0 0.0 10.0 Bottom 10.0 0.0 3.3 0.0 Ripening changes Peel yellowing (increasing peel color index or PCI) increased with period of storage in both HW-treated and untreated mangoes (Figure 4). Stack position of fruit did not cause wide variations in PCI. Similarly, colorimetric L*, a*, and b* values did not markedly differ with treatment (Figure 2). Fruit reaching table-ripe stage differed with treatment (Figure 2). For HW-treated fruit, more samples from the top layer of the stack turned full ripe after 6 days of ambient holding, while the opposite was obtained for the control fruit. Fruit softened with ripening, indicated by decreasing firmness (Figure 5). Similarly, TSS and pH increased while TA decreased with ripening. No remarkable treatment effects on these parameters were obtained, except for TSS of control fruit after one day of holding in ambient, which was much higher in top-layer fruit (12 °Brix) than in middle- and bottom-layer fruit (6 °Brix). This deviation was not exhibited in other ripening parameters. Mango is a climacteric fruit that exhibits increased rates of respiration and ethylene production during ripening (Figure 6). HW-treated fruit from different stack layers showed inconsistent trend, while unheated fruit, regardless of stack position, showed declining trend in respiration rates (Figure 4). On the other hand, ethylene production rate appeared to show a climacteric trend as it increased with storage due to ripening regardless of treatment (Figure 4). Great variations were obtained after 5-7 days of storage in which middle-layer HW-treated fruit showed lower rates, while the same fruit for the unheated treatment showed much higher rates than the other treatments. . Figure 4: Peel color index (A), table-ripe fruit (B), L*(C), a*(D), and b*(E) values of HWT- treated and untreated ‘Carabao’ mango from top, middle, and bottom stack layers during transport. *significant differences among treatments based on ANOVA, p = 0.05. Means ± SE, n=30. A B D C E . Figure 5: Firmness (A), pH (B), total soluble solids (C), and titratable acidity (D) of HW- treated and untreated ‘Carabao’ mango from top, middle, and bottom stack layers during transport. *significant differences among treatments based on ANOVA, p = 0.05. Means ± SE, n=6. Figure 6: Respiration and ethylene production rates of HW-treated and untreated ‘Carabao’ mango from top, middle, and bottom stack layers during transport. *significant differences among treatments based on ANOVA, p = 0.05. Means ± SE, n=6. C B D A . Fruit initially contained high levels of vitamin C, which decreased with storage (Figure 7). Total phenolic content was highest in HW-treated fruit positioned at the middle stack layer, which is an indication that mangoes had high antioxidant properties at the ripe stage. Synthesis and accumulation of phenolic compounds often increase as fruits ripen. DPPH assay revealed no definite trend across treatments. Highest DPPH activity (about 91%) was obtained on the 5th day of storage in both HW-treated and untreated fruit from the bottom and middle stack layer, respectively. Higher DPPH activity indicates higher antioxidant content and greater ability to neutralize free radicals. Figure 7: Vitamin C (A), total phenolic content (B), and antioxidant activity (C) of HW-treated and untreated ‘Carabao’ mango from top, middle, and bottom stack layers during transport. Bars represent standard error. *significant differences among treatments based on ANOVA, p = 0.05. Means ± SE, n=6. A C B . Shelf-life attributes Weight loss increased with storage regardless of treatment (Figure 8). Weight loss was closely similar between HW-treated and untreated fruit at the end of storage. Highest weight loss of over 18% was obtained from top-layer HW-treated fruit and bottom-layer unheated fruit. Manifestation of fruit shriveling was noted on the 6th day of storage when ripening set in. At the end of storage, unheated fruit exhibited a higher extent of shriveling than HW-treated fruit. Figure 8: Weight loss and shriveling index of HW-treated and untreated ‘Carabao’ mango from top, middle, and bottom stack layers during transport. Bars represent standard error. No significant treatment differences were obtained at each observation period. Means ± SE, n=30. Figure 9: Anthracnose and stem end rot incidence of HW-treated and untreated ‘Carabao’ mango from top, middle, and bottom stack layer during transport. Bars represent standard error. Means ± SE, n=30. . Anthracnose body rots were more severe than stem-end rot infection (Figure 9). HW- treated fruit had lower anthracnose and stem-end rot incidence than unheated fruit, regardless of stack position. At the end of storage, less than 50% of HW-treated fruit had anthracnose symptoms, while it was more than 60% for untreated fruit. Stem-end rot affected less than 10% of HW-treated fruit except for top-layer fruits, while the untreated lot had more than 10-20% of fruit with symptoms of the disease. HW-treated fruit had better visual quality mainly due to reduction of disease incidence relative to that of untreated fruit regardless of stack position (Figure 10). At the end of the 9-day storage period, all HW-treated fruit had VQR of 5-6, while the untreated fruits had reached the limit of marketability (VQR 3). Figure 10: Visual quality rating of HW-treated and untreated ‘Carabao’ mango from top, middle, and bottom stack layers during transport. Bars represent standard error. Means ± SE, n=30. Conclusions The study monitored the conditions and quality of mangoes along the supply chain from Davao City, Davao del Sur in Mindanao to Carmona City then to Los Banos, Laguna. Physical damage, ripening behavior, biochemical changes, and disease susceptibility during transit and storage were evaluated. Temperature and humidity variations inside the mango boxes during transit were observed, with an average temperature and relative humidity of 29.21°C and 92.96%, respectively. Compression damage was dominant, especially in hot water (HW)-treated mangoes, while bruises were noted on untreated fruit positioned at the middle stack. Ripening was hastened in HW-treated fruit placed at the top layer during transit. HW-treated mangoes exhibited reduced weight loss, shriveling, and diseases, which improved visual quality. Untreated mangoes exhibited a slight increase in ethylene production while the respiration . rate decreased indicating onset of senescence. HW-treated fruit in the middle layer had a lower respiration rate compared to untreated fruit in the same layer. Higher total phenolic content was recorded in HW-treated fruit located in the middle stack layer while DPPH activity did not show a definite trend. Location of the carton boxes in the stack did not show wide variations in quality but hot water treatment did. At the end of the nine-day storage period, all HW-treated fruit still had an acceptable visual quality score of 5-6, while the untreated fruit had reached the limit of marketability (visual quality of 3). Acknowledgment The team is grateful for the funding support of the CGIAR for the Project on Fruit and Vegetables for Sustainable and Healthy Diets (FRESH): Work Package 4 - Postharvest and Inclusive Markets. References Department of Agriculture, 2013. High Value Crops Development Program (Program RA 7900), Mango [Online]. http://hvcdp.da.gov.ph/mango.htm. Esguerra, E.B., Chavez, S.M. & Traya, R.V. (2006). A modified and rapid heat treatment for the control of postharvest diseases of mango (Mangifera indica Linn. cv. Carabao) fruits. The Philippine Agricultural Scientist, 89(2): 125-133. Li, S., Tao, S., Zhang, J., Wu, L., Huan, C., & Zheng, X. (2020). Effect of calcium treatment on the storability and disease resistance in preharvest bagging mango fruit during room temperature storage. Journal of Food Processing and Preservation, 44(10), e14803. Mansour, F. S., Abd-El-Aziz, S. A. & Helal, G. A. (2006). Effect of fruit heat treatment in three mango varieties on incidence of postharvest fungal disease. Journal of Plant Pathology, 88(2): 141-148. Pasilan, M.O., Secretaria, L.B., Bayogan, E.V., Lubaton, C.S., Dacera, D.D., & Ekman, J. (2020). Effect of rapid hot water treatment on some postharvest quality characteristics of Philippine ‘Carabao’ mango (Mangifera indica L.). South-western Journal of Horticulture, Biology and Environment, 11(2): 97-109. Philippine Council for Agriculture, Aquatic and Natural Resources Research and Development (PCAARRD-DOST). 2019. DOST-PCAARRD’s R&D Initiatives to Advance the Mango Industry [Online]. http://www.pcaarrd.dost.gov.ph/home/portal/index.php/quickinformation-dispatch/2925-dost- pcaarrd-s-r-d-initiatives-to-advance-the-mangoindustry. Shuck, V. A., Lacap, A.T., Secretaria, L.B., Cabardo, J.J.S., Kobayashi, Aguinaldo., R.T., Pasa, A.R., De Castro, R. D., Lopez, M.A. 2023. Adoption of pre- and postharvest technologies to improve the competitiveness of ‘Carabao’ Mango in the local and international markets. Final Report [Unpublished]. Australian Centre for International Agricultural Research (ACIAR)-John Dillon Fellowship. . Cover photo credit: Bioversity International / D. Hunter. Copyright © This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0). This research is being implemented by CGIAR researchers from IFPRI, CIMMYT, The Alliance of Bioversity International and CIAT, IWMI, and CIP in close partnership with World Vegetable Center, Applied Horticultural Research, the University of Sydney, the Institute of Development Studies, Wageningen University & Research, and the University of California, Davis. We would like to thank all funders who support this research through their contributions to the CGIAR Trust Fund: www.cgiar.org/funders The views and opinions expressed in this publication are those of the author(s) and are not necessarily representative of or endorsed by CGIAR. The CGIAR Research Initiative on Fruit and Vegetables for Sustainable Healthy Diets (FRESH) aims to use an end-to-end approach to increase fruit and vegetable intake and in turn improve diet quality, nutrition and health outcomes while also improving livelihoods, empowering women and youth and mitigating negative environmental impacts.