What Are the Best Melon Harvest Maturity Indices?

• The harvest maturity indices vary based on the melon groups.
• The physical harvest maturity indices are size, shape, weight, color, firmness, stem detachment, and tendril condition.
• The chemical harvest maturity indices include Brix/sweetness, titrable acidity, taste, and aroma.

The optimal harvest maturity index for melon differs for each accession. Several aspects of the ripening process must be considered to determine the optimal harvest index for setting picking times for the various melon groups. A combination of harvest maturity indices is most often used for melons. Find out what the standard harvest maturity indices are and how they vary for melon varieties and different regions of the world.

Melons are Climacteric and Non-Climacteric

Melons are Cucumis melo subspecies melo L., which are very diverse and include honeydews to cantaloupes. The existence of both climacteric and non-climacteric ripening in different groups of melons influences the development during maturity. Development of color, texture, sweetness, and taste, therefore, differs widely.

• Climacteric melons have a netted rind and can develop more sweetness and aroma, but have a shorter shelf life due to softening caused by the involvement of ethylene in ripening.
• Non-climacteric melons have less aroma, but are sweeter than climacteric melons. They don’t produce ethylene and ripen slowly, resulting in a longer shelf life.

These aspects must be considered when deciding on the harvest maturity indices to determine the optimal harvest time. Choice of harvest maturity indices for melons is also influenced by end-use, transport distance, and time. Melons consumed ripe and sweet are cantaloupes, casabas, honeydew, and muskmelons. Others consumed when immature include adzhur and snake melons.

Sweetness, flavor, color, and texture are attributes that influence consumer preference and are also used to determine the optimal harvest time. In addition to these standard parameters, some harvest indices are unique to melons, like tendril freshness, etc., and are discussed below.

Melon Physical Harvest Maturity Index

The physical features used as the harvest maturity index in melons are size, shape, weight, color, firmness, stem detachment, and tendril color.

Other minimum harvest maturity indices are the senescence of the leaf closest to the fruit and stem scar development.

Size, shape, and weight

Accessions of the different melon groups can have characteristic size, shape, and weight, which growers can allow the fruits to reach before harvesting. This knowledge can be gained from experience accumulated over previous years or information provided by breeders.

For example, in Iran, accessions Samsouri and Garmak (of variety Cantalupensis) have a width of 159-162 cm, while Kermanshah (variety Dudaim) has only 54-63 cm. Khatouni (variety Inodorus) has a length of 274-364 cm, and Kermanshah has 69-74 cm. Garmak, Samsouri, and Khatouni melons harvested late are heavier.

Table 1: “Affect of ground colour as a maturity index on slipping, pulling, netting and net toughness of muskmelon fruit,” Ahmed (2009). Credits: https://scispace.com/pdf/evaluation-of-objective-maturity-indices-for-muskmelon-1na7x2ppv0.pdf

Rind color

The most common harvest index used globally for melons is the rind and flesh color. Rind color changes are one of the first observable signs of maturity. The ground color changes to yellow or brown, the ground spot becomes yellow, and yellowing starts at the slip area. The color changes occur due to the breakdown of green chlorophyll to reveal carotenoids. The ground color of the rind is closely correlated with other maturity indicators, such as slipping, netting, and pulling, as shown in Table 1.

In the USA, color change below the netting in cantaloupe and the ground color in indeterminate fruits is used as a harvest maturity index. Rind hue values of 90°(yellow) and 100° are necessary at harvest.

• Melons with short shelf-life, CM2190 (cantalupensis × reticulatus), La Jolla (cantalupensis) turn from green to yellow.
• Melons with long shelf life, such as honeydew varieties, CM2327, Tacana, Tonga, and Fiji, change from green to white.

In Sudan, melons with a 50% brown color are best for fruits slated for export. These melons could also avoid pathogenic contamination in the stem cavity. Melons at this stage had the best netting, size, and sweetness.

In Iran, the Kermanshah and Zangi-Abad accessions have green stripes that turn orange to brown at maturity, as shown in Figure 1.

Nowadays, precise color changes in terms of hue and chroma are tracked, requiring advanced precision tools such as colorimeters or near-infrared spectrometers.

Figure 1: The ground color and stripes change color from green to yellow and brown in Zangiabad, a Dudaim accession, Hatami et al. (2016). (Image credits:  https://ijhst.ut.ac.ir/article_58163_ce080351da608514304052ccfa5a5615.pdf)

Internal flesh color

The melon flesh color is crucial for consumer acceptance and is used as the harvest index, especially in varieties where external rind color changes with maturity are not substantial. The flesh color of various melons is orange, green-white, and white for Cantaloupe, Inodorus, and Dudaim melons, respectively.

In Iran, melons harvested later have more hue and chroma than early harvests in accessions Khatouni, Samsouri, Garmak, Kermanshah, Kangavar, and Zangi-abad.

Number of strips

Some other appearance changes, also used in specific stripped accessions and varieties, include counting the number of strips. The number of strips can vary as maturity progresses and can either decrease or increase depending on the array.

In Iran, Samsouri and Khatouni accessions have an average of 9.83 strips per fruit and

Kermanshah and Zangi-Abad have an average of 10.67 and 10.35 strips, respectively. Khatouni and Zangi-Abad strip numbers are higher in late maturity, while in Samsouri and Kermanshah, strip numbers are higher in early harvested melons.

Netting

Netting is found in the reticulatus melon group, which produces ethylene. Netting is the area between net strands. Dense netting has less area between stands.

Galia cantaloupe has medium netting and achieves this stage by the 50% brown color level in Sudan.

In Iran, more netting was seen in late-harvested Kangavar. Netting can remain the same in Samsouri accessions at early and late maturity.

Slip development/ Stem detachment.

The development of a slip or an abscission layer between the fruit and the vine determines melon maturity. At full ripeness, the fruit can separate from the stem on its own. Before that, the fruit goes through the quarter and half-slip stages when the abscission layer is not fully formed, and a little force is needed to separate the melon from the vine. Honeydews do form the abscission layer, so this method can’t be used to judge their maturity. In the USA,

• Melons with a short shelf-life meant for the local market and immediate consumption are harvested at the 3/4th or full-slip stage.
• Melons meant for export and long-distance transport are harvested at the quarter and half-slip stage, when the fruit is less mature. These have a visible crack at the peduncle base.

In Sudan, half-slip will have 25-50% ground color, which is suitable for the long-distance market. Full-slip melons are at advanced stages of maturity, have a short shelf life, and are ideal for local markets.

Tendril and peduncle condition

In some places in the world, the cracking or development of an annular ring at the base of the peduncle is used to judge maturity. At the half-slip stage, the cantaloupe begins to show cracking. Also, the tendril close to the peduncle dries up. This condition is variety-specific and can’t be used for all melons.

In Iran, the Samsouri accession is harvested when there is no tendril in front of the peduncle. Khatouni accessions at early and late harvest still have green tendrils. The peduncle itself remains green.

Flesh firmness

As the fruit matures, the rind of the cantaloupe becomes softer, so firmness can be used as a harvest maturity index, and will be variety-specific. Figure 2 (E) gives the firmness in “N” for seven varieties in the USA that indicate harvest maturity.

In Iran, the accessions Kermanshah, Zangi-Abad, and Samsouri, which are harvested early, are firmer than those harvested late. Samsouri melon rinds are the softest at full maturity.

Crunchiness and juiciness are other new texture-related parameters that are suggested for use as a harvest maturity index.

Chemical Harvest Maturity Indices

Besides the physical parameters, internal quality attributes such as sweetness, acidity, taste, and aroma, measured both non-destructively and destructively, can be used as a harvest maturity index.

Figure 2: “Physicochemical properties of seven melon genotypes at harvest and postharvest. (A) Respiration rates; (B) ethylene rates; (C) rind coloration; (D) flesh coloration; (E) flesh firmness; (F) soluble solid contents (SSC); (G) titratable acidity (TA); (H) SSC/TA ratio. Genotype #1 (CM2190), #2 (La Jolla), #3 (CM2327), #4 (Tacana), #5 (Tonga), #6 (Fiji), #7 (MegaPac),” Farcuh et al. (2020). (Image credits: https://pmc.ncbi.nlm.nih.gov/articles/PMC7576513/) 

Total soluble solids

Total soluble solids (TSS) are measured to judge the sweetness of fruits. As the fruit matures and develops color and the abscission layer, the sweetness of melons increases. Sweetness is measured at three places in the fruit: close to the center cavity, the middle of the pulp, and near the rind see Figure 3. Melon is sweetest at the center with a gradual decrease toward the skin. It can be estimated as Brix by refractometers or NIR spectrometers.

The U.S. Department of Agriculture has set standards of 11% TSS as the harvest maturity index for melons. Some standard harvest maturity TSS for seven varieties in the USA are given in Figure 2 (F).

In Sudan, melons must have 11% TSS for harvest. TSS were the sweetest in all three places of estimations (11.80% at the rind, 13.16% in the middle, and 14.60% at the center) at the 50% brown level compared to immature and more mature stages. Therefore, it is considered the best time to harvest.

In Iran, mature honeydew had TSS in a range of 10–14° Brix, above the required 10° Brix. Late-harvested Garmak had the highest total soluble solids (TSS) values, and early-harvested Khatouni had the lowest TSS values.

Figure 3: “Sampling regions used in assessing soluble solids concentration within muskmelon

fruits, where: (A) Pulp, (B) cavity, and (C) skin regions. (1) Near cavity, (2) middle of pulp, and (3) near skin,” Ahmed (2009). (Image credits: https://scispace.com/pdf/evaluation-of-objective-maturity-indices-for-muskmelon-1na7x2ppv0.pdf).

Titrable acidity

Titrable acidity (TA) and pH are higher in earlier stages of maturity and harvest, and reduce as maturity progresses, as they get broken down for respiration or converted to sugars. TA varies with varieties and planting dates. The required TAs for seven varieties in the USA are given in Figure 2 (G).

Taste

Taste, which is the ratio of TSS to TA, is another harvest indicator. It is calculated using the sweetness and acidity values. Some standard taste requirements for melons for seven varieties in the USA are given in Figure 2 (H).

Aroma

Aroma is a product of several volatile compounds in the melons and is a sought-after quality by consumers. Therefore, the aroma is determined manually to determine the optimal harvest time. The presence of aroma is an indication that the fruit is ready for harvest, once the rind is yellow and cracking begins at the base of the peduncle.

In the USA, melons with short shelf lives, such as CM2190 (cantalupensis × reticulatus) and La Jolla, exhibit a distinct, detectable aroma at harvest maturity.

Melons with long shelf-life or honey dews, like CM2327, Tacana, Tonga, and Fiji, have none or a slightly detectable aroma, indicating they are ready for harvest.

NIR Spectrometers for Harvest Maturity Indices Measurement

Visual-NIR spectroscopy-based devices are standard precision tools used in the fruit supply chain to monitor the quality and maturity of fresh produce. Felix Instruments Applied Food Science offers small, portable devices designed for fruit analysis, including the F-750 Produce Quality Meter. The device is designed for on-site use, requires little training, and provides actionable and precise results in real-time. The device can be used to non-destructively track several parameters used as harvest maturity index- SSC, TA, and internal and external color.

The company will soon offer a device specifically designed to measure °Brix for melons (cantaloupes and honeydews), called the F-751 Melon Quality Meter.

Find out more about the Felix Instruments Applied Food Science’s tools for measuring melon harvest maturity at the farm and quality in the postharvest stages.

Sources

Ahmed, O. K. (2009). Evaluation of Objective Maturity Indices for Muskmelon (Cucumis melo) cv.” Galia”. J. King. Abdulaziz. Univ. Sci, 21(2), 317-326.

Bruktawit Tsehay, B., & Farcuh, M. (2025, May 5). Ripening Behaviors and Harvest Indexes of Watermelons, Cantaloupes, and Honeydew Melons. Retrieved from https://extension.umd.edu/resource/ripening-behaviors-and-harvest-indexes-watermelons-cantaloupes-and-honeydew-melons/

Farcuh, M., Copes, B., Le-Navenec, G., Marroquin, J., Cantu, D., Bradford, K. J., Guinard, J. X., & Van Deynze, A. (2020). Sensory, physicochemical and volatile compound analysis of short and long shelf-life melon (Cucumis melo L.) genotypes at harvest and after postharvest storage. Food chemistry: X, 8, 100107. https://doi.org/10.1016/j.fochx.2020.100107

Farcuh, M., Copes, B., Le-Navenec, G., Marroquin, J., Jaunet, T., Chi-Ham, C., … & Van Deynze, A. (2020). Texture diversity in melon (Cucumis melo L.): Sensory and physical assessments. Postharvest Biology and Technology, 159, 111024.

Hatami, M., Kalantari, S., & Soltani, F. (2016). Different ripening indices and quality attributes of different groups of Cucumis melo. International Journal of Horticultural Science and Technology, 3(1), 69-76.

a