Low concentration 1-MCP limit ripening process of mango cv. ‘gedong gincu’ during low temperature storage

Mango fruit still ripens and senesces after harvest. The presence of ethylene will shorten the shelf life of mangoes during long transportation processes. The purpose of this research is to find out how long the ‘gedong gincu’ mango (Mangifera indica L.) can be kept at 15°C after being treated with 1-methylcyclopropene (1-MCP). This study conducted experiments in the lab using a completely randomized approach with a single factor that included treatment with and without 500 ppb 1-MCP. Both was kept at 15°C for both sessions. Weight, color, hardness, total dissolved solids, total titrated acid, and chilling injury score were measured in this study. Analysis of data will be conducted using a t-test at α = 5% using Microsoft Analysis Toolpak. The study found that adding 1-MCP to mango cv ‘gedong gincu’ had a significant effect (p<0.05) on its color change, hardness, total titrated acidity, and chilling injury score during storage at low temperatures. This suggests that 1-MCP may be able to delay the ripening process by ethylene and extend the shelf life of ‘gedong gincu’ mangoes when stored at 15°C, thereby contributing largely to food loss prevention.


Introduction
Mangoes (Mangifera indica L.) are essential to Indonesia's agricultural landscape and are considered one of the country's foundation fruit crops.Mangoes are incredibly important to domestic consumption and worldwide commerce due to their juicy flesh, fragrant scents, and numerous culinary applications.Mangoes are consumed domestically and exported globally.In 2021, mango production in Indonesia is around 2.84 million tons, with 10% of them being exported [1].Gedong Gincu mango is an Indonesian premium variety of mango that is well-known for its sweet and fragrant fragrance.It is important for Indonesia's export industry [2].However, the path of fruit from the orchard to the market is plagued with challenges, particularly in the postharvest phase.Factors relating to shelf life and ripening stand as major drivers of quality and marketability.
Mangoes have a high degree of perishability, rendering them vulnerable to rapid degradation in the absence of efficient postharvest management.Ripening control is a critical component that significantly contributes to prolonging the shelf life and preserving the quality characteristics of the fruit [3].Ripening in fruits is highly dependent on ethylene production.Ethylene is an endogenous phytohormone that assumes a pivotal function in the maturation mechanism of diverse fruits, including mangoes.The molecule functions as a signaling entity that initiates and governs the physiological alterations linked to the ripening process of fruits [4].To extend the shelf life of mangoes during transportation, it is necessary to suppress ethylene production.Utilizing ethylene inhibitors, such as 1-methylcyclopropene (1-MCP), has become a crucial strategy for extending the shelf life of products [5].
1-MCP is a gaseous molecule that has the ability to be absorbed by ethylene receptors located on the outside of plant cells.These receptors are responsible for initiating a signaling cascade that subsequently induces a range of physiological and biochemical alterations connected with the process of ripening.When 1-MCP gets absorbed into the cellular structures of plants, it engages in a competitive interaction with ethylene for the purpose of binding to ethylene receptors.Significantly, 1-MCP exhibits a higher affinity and stronger binding to these receptors than ethylene.The competitive binding process serves as a mechanism that delays the attachment of ethylene to its receptors, hence limiting the initiation of the typical ripening signal [6].In the past, numerous experiments have been conducted on mango fruit utilizing 1-MCP.Applying 1-MCP treatment at a concentration of 500 parts per billion (ppb) at room temperature has been seen to increase the shelf life of Chokanan mangoes by 7 days compared to untreated mangoes [7].An independent study examined the use of 1-MCP on 'Alphonso' mango fruit at lower temperatures, showcasing the ability of 1-MCP to prolong the fruit's shelf life while maintaining its quality [8].
Currently, there is a lack of published information about the 1-MCP utilization on gedong gincu mango varieties.1-MCP has the ability to significantly increase the shelf life of Gedong Gincu mangoes, making them valuable commodities that can be exported to other countries.Furthermore, the effective implementation of the export procedure greatly depends on the use of temperature control as a crucial factor in extending the fruit's storage duration.This study seeks to examine the effect of the integration of 1-MCP during cold storage on the prolongation of fruit shelf life.

Material
The mango fruit was collected from Cirebon after it reached its mature stage approximately 100 days after flower bloom.The fruits were transported to the Postharvest Laboratory at Universitas Muhammadiyah Yogyakarta within a period of 10 hours.The fruits were categorized according to their absence of physical abnormalities or injuries, as well as their adherence to the standard color.Subsequently, the fruits underwent a chlorination process to effectively eliminate any residual debris and spores.Before the 15℃-temperature storage period, the fruits were prepared to receive the treatments, which included both the addition of 500 ppb 1-MCP as a main treatment and absence of 1-MCP as control.

Observation
The observations consisted of weight loss, fruit hardness, change in color, total soluble solids, total titrated acidity, and chilling injury score.The weight loss was assessed by measuring the difference in fruit weight between the day of observation and the day of treatment utilizing the OHAUS SPS402F (OHAUS, USA) analytical balance.The data were expressed as percentages (%).The hardness of the fruit was evaluated using a fruit hand penetrometer FR-5120 (LUTRON, USA), and the final calculation were reported in N.mm -2 .The change in fruit color during storage was examined using Munsell Colour Charts for Plant Tissues (Munsell, USA).The fruits' total soluble solids were measured using the digital hand refractometer RA-130 (KEM, Japan), and the results were reported in brix°.The titration procedures recommended by AOAC were used to analyze the total titrated acidity content [9].The chilling injury score was done based on the chilling level with 0 (chilling in 0% of fruit area) to 5 (chilling in 80-100% from total area).

Data Analysis
The t-test analysis with 95% confidence level was employed to examine the statistical differences between the control and the 1-MCP group using Microsoft Analysis Toolpak (Intel, USA).At least three replicates of each measurement were independently determined.

Fruit Weight Loss
The weight loss observed during storage can be related to water transpiration from the fruit tissue through the stomata or fruit skin.The results of the t-test examination of fruit weight decrease reveal no statistically significant difference (p>0.05) between the group treated with 1-MCP and the control group.The weight loss graph shows the fluctuations in the proportion of weight loss through a 20-day duration in mango fruit subjected to low temperature storage, comparing the effects of 1-MCP treatment with the control group (figure 1A).Prior studies have demonstrated that using 1-MCP did not showed any significant effect on weight reduction in `Kent` mango fruit [10].The respiration rate of climacteric fruit is comparatively higher than that of non-climacteric fruit.The results of this study indicate that the use of 1-MCP treatment did not successfully inhibit transpiration in 'gedong gincu' mango fruit stored at low temperatures, as supported by the absence of significant changes in weight loss observed in the different treatments.

Total Dissolved Solids
No significant differences were seen between the two treatments except on days 4 and 16 (p<0.05).The data suggest a delay in the TSS value elevation after being treated with 1-MCP.This study demonstrates that the implementation of 1-MCP treatment successfully suppresses starch degradation, resulting in a decrease in total soluble solids (TSS) compared to samples that did not undergo 1-MCP treatment.During the ripening and aging process, complex polysaccharides and starch molecules convert into simpler sugars, increasing the overall amount of soluble solids [6].Previous research has indicated that the application of 1-MCP can successfully maintain the total soluble solids (TSS) content in bananas.Moreover, combining 1-MCP with cold storage has been discovered to significantly extend the storage life of various agricultural commodities [11].

Firmness
Typically, the firmness of fruits tends to diminish throughout the course of storage.The firmness of mango fruit, both in the 1-MCP treatment and the control groups, showed a steady decrease throughout the storage period (figure 1C).A statistically significant difference (p<0.05) in fruit hardness was observed between the two treatments on both the fourth and eighth day of observation.The study's results indicate that using a small amount of 1-MCP can successfully delay fruit softening at the beginning of cold storage.The firmness of 'gedong gincu' mango fruit gradually decreases over storage when exposed to 1-MCP at a concentration of 500 ppb.Nevertheless, it was observed that the softening process in the 1-MCP treatment exhibited a slower rate compared to the control treatment.This phenomenon manifests during the initial stages of cold storage, but its occurrence diminishes towards the later stages of storage.This phenomenon could be attributed to the insufficient concentration of 1-methylcyclopropene (1-MCP), which may have resulted in a limited ability to suppress ethylene activity over an extended period effectively.This result was similar with previous reported that 1-MCP could inhibit softening in 'Tainong' mango [12].
An increased generation of ethylene is linked to a heightened process of cell wall degradation in the skin of fruits.Fruit produces many enzymes that facilitate the breakdown of the cell wall.These enzymes comprise cellulase, a key component in the decomposition of cellulose, along with polygalacturonase (PG) and pectin methylesterase (PME), which participate in the breakdown of pectin.PME is an enzyme that acts as a catalyst to simultaneously break down cellulose and hemicellulose.This enzymatic activity leads to an elevation in the fruit respiration rate, ultimately culminating in the climacteric peak.Consequently, the turgor pressure within the cell wall diminishes, resulting in the softening of the fruit.During the process of storage, deterioration takes place, leading to alterations in the composition of the cell walls of fruits, ultimately resulting in a softening of the fruit's texture [13].

Colour change
The color of fruit commodities serves as a sign of their freshness.The maintenance of fruit color is significantly impacted by the storage temperature, hence influencing its brightness level.The degradation of pigments may be enhanced as a consequence of an accelerated ripening process, whereas a reduction in the pace of ripening leads to a delay in the occurrence of color alterations.The initial hue of the gedong gincu mango fruit in both treatments is observed to be dark green, which subsequently undergoes modifications throughout the course of storage (Table 1).The fruit in the control group underwent a transition in color, turning yellow on the twelfth day, while the fruit in the 1-MCP treatment group exhibited this shift on the eighteenth day.The study's findings revealed that fruit treated with 1-MCP effectively prevented color changes, as demonstrated in Table 1.Similar findings were documented in previous study on tomatoes subjected to 1-MCP treatment, which effectively suppressed the alteration of fruit color [14].1-MCP functions as an ethylene inhibitor by transmitting chemical signals to receptors that are associated with the ripening process, including chlorophyll degradation [15].Ethylene exerts an influence on fruit deterioration, initiates the breakdown of chlorophyll, and expedites the process of senescence [13].The utilization of 1-MCP in fruit preservation can effectively impede the transition from a green hue to a yellow hue, which is mostly attributed to the chlorophyll breakdown and the carotenoids production [16].

Total titratable acidity
During the storage phase, the titratable acidity (TA) values exhibited no statistically significant differences (p>0.05).Nevertheless, the treatment group without 1-MCP exhibited significantly higher values in comparison to the group treated with 1-MCP (p<0.05).This observation indicates that the enzymatic conversion of sugar into acid remains elevated, leading to a subsequent decline in total acidity (TA) levels on the eighth day in the treatment group without the addition of 1-MCP (figure 1D).Conversely, it was noted that treatment with 1-MCP led to a greater level of consistency in the total acidity (TA) value, preserving its level until the 8th day.The results suggest that the use of 1-MCP can successfully inhibit the deterioration of total acidity (TA) when stored at a temperature of 15 ℃.The prior study also showed similar results when examining the impact of 1-MCP treatment on 'Khirshapat' mango fruit [17].The treatment has been found to efficiently maintain enzyme activity, consequently impacting the acidity level of the fruit.

Chilling injury score
The occurrence of chilling injury is a significant factor to consider while preserving fruit at low temperature conditions.The present investigation involved the assessment of chilling injury symptoms on the fruit through the application of a severity grading system.The observed symptoms encompassed several manifestations such as skin discoloration and pitting, sunken lesions, lenticel patches, and fruit skin shrinkage [11].Based on the findings of the chilling injury scoring analysis (figure 1E), it is evident that the treatment group receiving 1-MCP exhibited a decreased incidence of chilling injury symptoms compared to the control group.This study provides evidence that the use of 1-MCP therapy effectively suppresses the development of chilling injury symptoms in 'gedong gincu' mango.Previously, it is reported that the use of 1-MCP treatment effectively mitigates phenolic oxidation, which is linked to the activity of polyphenol oxidase and peroxidase [6].Consequently, this treatment leads to reduced pigmentation in both the skin and flesh of fruits, thereby preventing the occurrence of chilling injury symptoms.In the context of damaged fruit tissue, there will be an elevation in ethylene production, subsequently leading to an increase in respiration.The application of ethylene to a wound site elicits many metabolic responses, such as the upregulation of key enzymes including polyphenol oxidase, peroxidase and phenylalanine ammonia lyase.When a fruit is harmed, an oxidative reaction takes place wherein the fruit's constituents react with oxygen, resulting in a change in color to brown, sometimes referred to as enzymatic browning [18,19].

Conclusions and Suggestions
According to the findings and analysis, it can be concluded that applying 1-MCP treatment at a low temperature of 15 ℃ helps to extend the shelf life of 'gedong gincu' mango through maintain total soluble solids (TSS), titratable acidity (TA), hardness, and preventing color changes, hence reducing the occurrence of chilling injury symptoms.Finally, the utilization of 1-MCP significantly enhances the duration of product freshness, hence playing a crucial role in mitigating food waste and promoting sustainable agricultural practices.

Figure 1 .
Figure 1.The weight loss (A), total dissolved solid (B), fruit firmness (C), total titratable acidity (D), and chilling injury score (E) of 'gedong gincu' mango treated with and without 1-MCP after 20 days storage at 15 ℃.Data are shown as mean ± SD.The asterisk on the line graph denotes statistically significant changes (P<0.05) between two treatments at each storage time.The abbreviation "NS" on the line graph signifies non-significant differences (P≥0.05) between two treatments at each storage time.

Table 1 .
The color changes of 'gedong gincu' mango treated with and without 1-MCP treatment after 20 days storage at 15 ℃.