pom212_papaya_and_guava_2005_handout

pom212_papaya_and_guava_2005_handout - Papaya Carica papaya...

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Unformatted text preview: Papaya Carica papaya • Fleshy berry • Also known as pawpaw • Cultivars vary in shape and size – Elongated to spherical – 7 to 30 cm long, up to 9 kg – Solo is 500 g Papaya • Latex – In every part of plant – Contains two proteases • Papain and chymopapain • Sold as meat tenderizer • Tree trained to single trunk • Fruit buds form progressively higher – Oldest fruit is lowest Maturity • Surface yellowing – Mature green, color break, ¼, ½, ¾ yellow ¼, ½, – Harvested color break to ¼ yellow for export; ½ to ¾ yellow for local market Quality • Papayas harvested at ¼ yellow or more taste better • Soluble solids do not increase after harvest • Flesh color changes from green to yellow or red depending on cultivar • Minimum soluble solids in Hawaii 11.5% – equivalent to 6% surface yellow color 1 Maturity Stages of Papaya Ripeness 2 Green Islands from Skin Abrasions Chlorophyll retained Accelerated water loss Chilling Injury • Mature green – 10 days at 2°C – 20 days at 7.5°C • ½ yellow – 17 days at 2°C • Preconditioning (partial ripening) reduced chilling sensitivity Recommended Temperatures • 13°C for mature green to ¼ yellow • 10°C for partially ripe (1/4 to ½ yellow) • 7°C for ripe (> ½ yellow) 3 Controlled Atmosphere Storage Limited research Optimum 3 to 5% O2 + 5 to 8% CO2 2 2 5% CO2 + 1-1.5% O2 extended postharvest 11-1.5% 2 2 life, delayed ripening • 10% CO2 reduced decay 2 • Postharvest life at 13ºC 13º 13ºC – 2 to 4 weeks in air – 3 to 5 weeks in CA • • • • Damaging atmospheres – < 2% O2; > 8% CO2 2 2 Cell Wall Enzymes • Polygalacturonase and xylanase activity increase temporally at beginning of climacteric – Pectin hydrolysis important late in ripening Natural Ripening Inhibition in Papaya • Benzyl isothiocyanate – Endogenous regulator of ethylene production – Inhibits in vitro ethylene production in disks from pre-climacteric fruit, no effect prepre-climacteric on RS – No effect on post-climacteric tissue postpost-climacteric – Thought to inhibit induction of ethylene synthesis – Also has some antifungal properties; role in natural defense – Concentration decreases with ripening • Cellulase and pectin methylesterase increase throughout ripening • Proteinase decreases with ripening Quarantine Treatments • Two-stage hot water treatment TwoTwo-stage – 30 min at 42°C, 20 min at 49°C – ¼ yellow or less – Phytotoxicity • Hard spots in fruit • Surface scalding Quarantine Treatments • Forced hot air – Multi-staged treatment MultiMulti-staged • 43°C 2h, 45°C 2h, 46.5°C 2h, 49°C until center reaches 47.2°C – New 48.5°C for 3 hours • Irradiation – Linear relationship between dose and firmness after irradiation; slowed softening – Effect depends on fruit stage at treatment • MG – no effect on softening • 30% color – slower softening after 250 Gy • Determined ineffective in Solo papaya due to blossom end defect 4 Center of Papaya Fails to Soften after Heat Treatment External Scalding of Papaya after Heat Treatment Methods to Reduce Heat Sensitivity • Continuous – Hold at temperature below 40°C for 2 to 4 hours • Heat Pulse – 1 hour at 38°C, wait 3 hours, then treat – 30 min at 42°C, cool to 20°C, then treat 5 6 7 8 Guava Psidium guajava • Juicy berry • Small tree or shrub, grows fast, weed • Native to tropical America • Grown in Florida, Hawaii, India, Australia, Japan, Brazil Some types are eaten ripe 9 Internal flesh can be white, yellow, pink or red Asian types are eaten green Guava Characteristics • One of richest sources of Vitamin C • Good source of Vitamin A, and minerals K, Ca, Fe • Mesocarp tissue contains stone cells – Give a gritty texture Maturity Indices • Skin changes green to yellow (some cultivars) – Firm yellow stage for long-distance transport longlong-distance – Half ripe stage (softer) for local market – Some are harvested mature green and eaten light green (Asian types) • Climacteric • Chilling sensitive – Mature green ≥ 10ºC 10º 10ºC – Turning 7ºC for up to 3 weeks 7º 7ºC – Fully ripe guavas - 5 to 8ºC for up to 1 week 8º 8ºC • • • • Ratio soluble solids to titratable acidity Decrease in detachment force Specific gravity change (<1.0) Tannin content decreases with maturity – Polyphenols give astringency to immature fruit – Increase in PPO activity with ripening • No increase in soluble solids after harvest Ethylene Treatment • 100 ppm for 1 to 2 days at 15-20ºC, 90 15- 20º 15-20ºC, to 95% RH – Accelerates ripening of MG guavas to full yellow – More uniform ripening, especially for processing – Immature green fruit will not ripen properly and develop gummy texture Controlled Atmosphere • Limited Research – 2 to 5% O2 may delay ripening of MG and 2 partially ripe guavas at 10ºC 10º 10ºC – 5% CO2 for 24h at 4ºC prior to storage in 4º 4ºC 2 air for 3 weeks at 4ºC prevented chilling 4º 4ºC injury after transfer to 20ºC 20º 20ºC 10 Effect of 1-MCP 11-MCP • 300ppb for 6 to 12 hours and 900 ppb for 3 hours • Delays ripening • Extends storage life • 900ppb for 6+ hours did not ripen at 20°C • Needs more research at storage temperatures. Maximum Shelf Life of ‘‘Pedro Sato’ Guava Fruit Pedro Sato’ Treated with 1-MCP and Stored at 25°C 11-MCP Skin Color of ‘Pedro Sato’ Guavas Treated with 1-MCP and held at 25°C Respiration Rate at 20°C of ‘‘Pedro Sato’ Guava Fruit Pedro Sato’ after 1-MCP Treatment 11-MCP Firmness of ‘‘Pedro Sato’ Guava Fruit after 1-MCP Treatment Pedro Sato’ 11-MCP and Full Ripening at 25°C Citric Acid Content of ‘‘Pedro Sato’ Guava Fruit Pedro Sato’ after 1-MCP Treatment and Full Ripening at 25°C 11-MCP 11 Storage Temperature • 8 to 10°C – mature-green and partially maturemature-green ripe guavas – 2 to 3 weeks • 5 to 8°C – fully-ripe fullyfully-ripe – 1 week 16 120 100 'Bangkok' guava 100 Respiration rate (mL CO2 kg-1h-1) 1 2 3 4 5 Pink flesh guava 6 7 (mL CO2 kg-1h-1) Respiration rate (mL CO2 kg-1h-1) Pink flesh gauva 'Mexican Cream' 'Bangkok' 120 14 12 10 8 6 4 2 Respiration rate 80 60 40 20 80 60 40 20 14 1 2 3 4 5 6 7 8 Ethylene production (µL C2H4 kg-1h-1) Ethylene production (µL C2H4 kg-1h-1) 12 10 8 6 4 2 0 1 Days of storage at 10°C 'Mexican Days of storage at 7.5°C Cream' 6 4 2 0 0.25 Ethylene production (µL C2H4 kg-1h-1) 'Bangkok' 0.20 1 5°C 2 7.5°C 10°C 12.5°C 3 4 5 6 7 Days of storage 0.15 0.10 2 3 4 5 6 7 1 2 3 4 5 6 7 0.05 Days of storage at 10°C Days of storage at 7.5°C 1 2 3 4 5 6 7 Days of storage 'Mexican Cream' guava 120 120 Pink flesh guava (mL CO2 kg-1h-1) Respiration rate 80 60 40 20 Respiration rate 100 (mL CO2 kg-1h-1) 100 80 60 40 20 14 Ethylene production (µL C2H4 kg-1h-1) Ethylene production (µL C2H4 kg-1h-1) 12 10 8 6 4 2 1 5°C 2 7.5°C 10°C 12.5°C 3 4 5 6 7 20 Days of storage 1 5°C 2 7.5°C 10°C 3 4 5 6 7 Days of storage 12.5°C 15 10 5 1 2 3 4 5 6 7 1 2 3 4 5 6 7 Days of storage Days of storage 12 Seedlings vary considerably In their characteristics Physiological Disorders • External and internal browning – Physical damage • Sun scald – Paper bags are sometimes used to cover fruit 13 Decay • Most diseases begin in the field – – – – – Stylar end rot – (Phomopsis destructum) Anthracnose (Colletotrichum gloeosporiodes) gloeosporiodes) Aspergillus rot (Aspergillus niger) Mucor rot (Mucor hiemalis) Rhizopus rot (Rhizopus stolonifer) • • • Careful handling Prompt cooling Fungicides Quarantine • Hot water – 46ºC for 33 min 46º 46ºC RF machine • Hot air – 48ºC for 53 min 48º 48ºC • Radio Frequency heating – 50°C for 3 minutes • Irradiation – 150 to 300 grays Thermal-death-time (TDT) curve of Thermal- deathThermal-death-time third-instar Mexican fruit fly thirdthird-instar Mexican 6 min 1.5 min 0.5 min 14 Guava Psidium guajava ‘Mexican Cream’ ‘Mexican Cream’ • Non commercial affect: – Internal browning – SS, TA Harvest 1 • Affected: – Harvest effect – Appearance of small circular brown spots – Firmness Percent of Mexican Cream Guava Fruit with Brown Spots Area affected with spots (%) Harvest 1 15 15 Phytosanitary control Estimated Probit 9 Extra timing Harvest 2 15 10 10 10 5 5 5 Control 24 48 50 52 Control 24 48 50 52 (°C) Treatment 48°C: 6, 12, and 18 min 50°C: 1½, 3 and 4½ min 1½ 4½ 1½, 52°C: ½, 1 and 2 min ½, 15 Severity of spots 2 Harvest 1 Phytosanitary control Harvest 2 Estimated Probit 9 Extra timing 2 Firmness of Mexican Cream Guava Fruit after Radio Frequency Treatment Phytosanitary control Extra timing 1 Extra timing 2 Harvest 1 Harvest 2 60 50 40 30 20 10 60 Firmness (N) 1 1 50 40 30 20 10 0 Control 24 48 50 52 Control 24 48 50 52 0 Control 24 48 50 52 Control 24 48 50 52 °C 0 = none or very slight 1 = moderate 2 = severe Treatment °C 48°C: 6, 12, and 18 min 50°C: 1½, 3 and 4½ min 1½ 4½ 1½, 52°C: ½, 1 and 2 min ½, Treatment 48°C: 6, 12, and 18 min 50°C: 1½, 3 and 4½ min 1½ 4½ 1½, 52°C: ½, 1 and 2 min ½, Guava Psidium guajava Asian ‘Bangkok’ • No commercial affect Control • Very slight external browning • Damage from shrivel RF treated 16 ...
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