Guava

MATURITY & QUALITY

Maturity Indices

Guava fruits are picked at the mature-green stage (color change from dark- to light-green) in some countries where consumers eat them at that stage. In countries where consumers prefer ripe guava, the fruits are picked at the firm-yellow to half-ripe (softer) stage for long-distance transport or at the fully-ripe (yellow and soft) stage for local markets.

Quality Indices

• Color is a good indicator of ripeness stage
• Size and shape may be important in some markets
• Freedom from defects, insects, and decay
• Firmness and extent of gritty texture due to the presence of stone cells (sclereids)
• Flesh color depends on cultivar and can be white, yellow, pink, or red
• Amount of seeds in the flesh (the fewer the better)
• Aroma intensity
• Soluble solids and acidity
• Guava is one of the richest sources of vitamin C (200 to 400 mg per 100g fresh weight) and some cultivars are also rich in vitamin A

TEMPERATURE & CONTROLLED ATMOSPHERE (CA)

Optimum Temperature

• 8-10°C (46-50°F) for mature-green and partially-ripe guavas (storage potential = 2-3 weeks)
• 5-8°C (41-46°F) for fully-ripe guavas (storage potential = 1 week)

Optimum Relative Humidity

90-95%

Rates of Respiration

To calculate heat production multiply ml CO₂ /kg·hr by 440 to get Btu/ton/ day or by 122 to get kcal/metric ton/day.

Rates of Ethylene Production

Guava is a climacteric fruit. Rates of respiration and ethylene production depend upon cultivar and maturity/ripeness stage. Ethylene production at 20°C (68°F) ranges from 1 to 20 µl /kg·hr.

Responses to Ethylene

Ethylene at 100 ppm for 1-2 days can accelerate ripening of mature-green guavas to full-yellow stage at 15-20°C (59-68°F) and 90-95% relative humidity. This treatment results in more uniform ripening, which is more important for guavas destined for processing. Immature-green guavas do not ripen properly and develop ‘gummy’ texture.

Responses to Controlled Atmospheres (CA)

The limited research on guava indicates that 2-5% oxygen levels may delay ripening of mature-green and partially-ripe guavas kept at 10°C (50°F). Tolerance to elevated carbon dioxide levels has not been determined.