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Section III
Tropical and Sub-Tropical Fruits
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16
Banana
Scot C. Nelson and Sarah J. Pethybridge
Contents
List of Abbreviations
16.1 Introduction
16.1.1 Physiological (Non-Parasitic) Postharvest Disorders of Banana Fruit
16.1.2 Banana Field and Cultivation Practices
16.1.3 Harvest and Packinghouse Practices
16.1.4 Transport, Ripening, and Marketing Practices
16.2. Disorders Arising from Cultivation Practices in the Banana Field
16.2.1 Bumpy Finger
16.2.2 Formic Acid Injury
16.2.3 Fused Fingers
16.2.4 Leaf Rubbing Injury (‘Alligator Skin’)
16.2.5 Twisted Finger, Malformed Finger
16.2.6 Maturity Stain (Maturity Bronzing)
16.2.7 Point Scars
16.2.8 Sinkers
16.2.9 Somaclonal Variation, Fruit Chimera
16.2.10 Sooty Mold, Sooty Blotch
16.2.11 Sunburn/Sunscald
16.2.12 Yellow Pulp
16.2.13 Wing Fingers
16.3 Disorders Arising from Harvest and Packinghouse Practices
16.3.1 Best Management Practices for Harvesting and Packing
16.3.2 Best Management Practices for Ripening
16.3.3 Bruised Peel and Pulp
16.3.4 Cracked or Split Finger
16.3.5 Latex (Sap) Stain, Sap Scars
16.3.6 Precocious Ripening, Mixed Ripening
16.4 Disorders Arising from Transport, Ripening, and Marketing Practices
16.4.1 Chilling Injury
16.4.2 High-Temperature Under-Peel Discoloration, High-Temperature Injury
16.4.3 Senescent Spots
16.4.4 Segmented Banana
16.4.5 Peel Abrasions
16.4.6 Withered Pedicels
16.5 Disorders Related to Gases During Shipment or Storage
16.5.1 Oxygen (O2) Deprivation
16.5.2 Ammonia (NH3) Injury
16.5.3 Carbon Dioxide (CO2) Injury
16.6 Physiological Mechanisms Associated with the Postharvest Disorders of Banana
16.7 Glossary of Banana-Production Jargon
16.8 Acknowledgments
References
List of Abbreviations
ASHRAE | American Society of Heating, Refrigerating and Air-Conditioning Engineers. |
CO2 | Carbon dioxide |
HCOOH (HCO2H) | Formic acid |
K+ | Potassium |
NH3 | Ammonia |
O2 | Oxygen |
R717 | A type of refrigeration equipment fueled by ammonia gas |
16.1 Introduction
16.1.1 Physiological (Non-Parasitic) Postharvest Disorders of Banana Fruit
In this chapter, we define a ‘postharvest physiological disorder’ of banana fruits as any abnormal symptom observed after harvest and caused by non-parasitic or etiological factors. These factors range from genetic mutations to any growing, handling, or fruit-processing practices performed or conditions experienced before, during, or after harvest. Therefore, the physiological disorders discussed exclude injuries caused by parasitic insects and diseases caused by plant pathogens.
We discuss the disorders in relation to commercial banana production, marketing, and modern consumer preferences. The discussion may not be relevant to home or local farming where fruits affected by many of these disorders are not suitable for supermarkets, but nonetheless may be safely consumed. Consumer preferences and some disorders are specified in published banana grading standards, such as those used in Hawai‘i, USA (Anonymous, 1986).
Postharvest physiological disorders do not necessarily begin after harvest, although that is primarily when they are expressed, noticed, or acted upon. The disorders derive from three distinct phases in banana production systems: (1) field and cultivation practices; (2) harvest and packinghouse practices; and (3) transport, ripening, storage, and marketing practices.
Many published sources describe the best practices for banana farming, harvesting, handling, ripening, and storage. It is not our purpose to fully replicate these materials, but to reference key points related to the cause and management of each disorder. We therefore provide relevant aspects of banana production and marketing that pertain to the postharvest physiological disorders of banana presented in this chapter.
16.1.2 Banana Field and Cultivation Practices
Some physiological disorders of banana fruits occur during cultivation but are not expressed, or noticed, until after harvest (Table 16.1). Proper management practices in the field can reduce the incidence and severity of blemishes on the fruit or disorders that result in culled or off-grade fruits (Table 16.2).
Table 16.1
Commercial Banana Bunch Management Practices
| Bunch Management Practice | Effect on Physiological Disorders |
| Proper fertilization practices (e.g., K + ) | Reduced incidence of sinkers and yellow pulp |
| Leaf removal. Remove leaves that rub against bunches. | Reduced incidence of alligator skin and leaf rubbing injury |
| Detrashing. Remove leaves having greater than 50% of leaf area covered by black or yellow Sigatoka. | Reduced incidence of precocious ripening |
| Bunch covers. Use perforated polyethylene sleeves to cover bunches. Tie the open ends closed at the top and bottom of the bunch. | Reduced incidence of sooty mold, sunscald leaf rubbing injury, and insect damage |
| Deflowering. Pluck female flowers from fingers twice per week before bagging with polyethylene sleeves, while the flowers are fresh (not dried). | Reduced incidence of sap stains (if not plucked when fresh, the dry flowers must be removed at the packinghouse, which starts sap flow and causes sap stain of fingers |
| Bunch sprays. Spray bunches with a fungicide before bagging. | Reduced incidence and severity of sooty mold, sooty blotch, and other fungal diseases |
| Avoid jarring pseudostems. Do not bump into pseudostems during field operations or at harvest. | Reduced incidence of formic acid injury to bunches and fruits caused by certain species of ants |
| Bag and tag the bunches. After plucking the female flowers, spray the bunch, cut off the male flower (the “bell”), bag the bunch, and tag with colored ribbons. This ensures that bunches of identical ages are harvested on the same date. | Reduced incidence of sooty mold, fruit abrasion injury and bunches of mixed ripeness |
| Gentle handling. Handle bunches with care during harvest and transport to the packing facility. | Reduced incidence of bruising |
| Rogue mutant plants. Remove plants with somaclonal variations produced during tissue culture. | Reduced incidence of somaclonal variation, mutant phenotypes and fruit abnormalities |
| Crop logging. Use an accepted crop logging and leaf sampling protocol for banana leaf tissue in your area1. Tissue analysis can help offset nutrient deficiencies (Table 16.2). | Reduced incidence of sinkers and yellow pulp |
1Laha, E., and Turner, D.W. 1989. Banana Nutrition. International Potash Institute Worblaufen-Bern, Switzerland.
Table 16.2
Recommended Levels of Elements in Banana Leaf Tissue in Hawaii (Silva & Uchida, 2000)
| Element | Symbol | Range (suggested) |
| Nitrogen | N | 2.8 – 3.1% |
| Phosphorous | P | 0.18 – 0.20% |
| Potassium | K | 3.2 – 3.5% |
| Calcium | Ca | 0.6 – 1.0% |
| Magnesium | Mg | 0.3 – 0.6% |
| Sulfur | S | 0.22 – 0.25% |
| Iron | Fe | 50 – 100 ppm |
| Manganese | Mn | 30 – 100 ppm |
| Copper | Cu | 10 – 15 ppm |
| Zinc | Zn | 25 – 40 ppm |
| Boron | B | 15 – 25 ppm |
16.1.3 Harvest and Packinghouse Practices
Proper harvest and packinghouse practices can reduce the incidence and severity of fruit blemishes and other physiological disorders (Table 16.3). More specific information on these practices appears later in the chapter.
TABLE 16.3
Best practices for banana harvesting and at packinghouses and their effects on various physiological disorders
| Harvest or packinghouse practice | Effect on physiological disorders |
| Gentle handling of bunc... |
