pom212-stone_fruits_ak_2005_handouts - Postharvest Biology...

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Unformatted text preview: Postharvest Biology and Technology of Stone Fruits Adel Kader UCDavis 1 Genotypic Variation in Post-cutting Life of Peaches and Nectarines Overall Quality Scores for Fresh-cut Peaches 2 Ethylene biosynthesis: Methionine Ethylene biosynthesis: Methionine SAM ACC synthase ACC ACC oxidase Ethylene Low O2 AVG, AOA SAM ACS ACC ACO Ethylene Silencing (mutation, antisense, sense) 1-MCP Receptor From: Bruno Defilippi Receptor From: Bruno Defilippi 3 Rating Scale for Chilling Injury (Internal Breakdown) of Peaches 4 5 6 7 8 9 1 2 3 4 5 Maturity and Ripeness Stages of Apricots Maturity and Ripeness Stages of Cherries 10 Cherry Color Charts Ground Color is used as a maturity/ripeness index for stone fruits California well mature Maturity and Ripeness Stages of Nectarines Maturity Stages of Cling Peaches Immature Partiallyripe 1 3 Maturity stage Skin color “a” Immature 9.8 9.5 10.8 Mature 11.7 8.8 12.0 Overmature 13.0 7.3 12.3 Maturegreen Ripe Flesh firmness(lbf) Soluble solids% 2 4 11 Rating Scale for Browning Due to Impact Bruising of Peaches INKING 12 Water Disinfection •Chlorine (calcium or sodium hypochlorite) •Chlorine dioxide •Ozone Currently Used Fungicides • 2,6_Dichloro_4_nitroaniline (DCNA, Botran, Allisan) • Fenhexamid (Elevate) • Fludioxonil (Scholar) 13 Optimal Storage Conditions: -1 to 1ºC 90 to 95% RH Storage Duration: 2 to 6 weeks, depending on cultivar 14 From: Carlos Crisosto (100% Mealy) Peach Delayed Cooling 5ºC 5ºC 20 Days (43% Mealy) (0% Mealy) 0ºC 20 Days 20ºC 48 Hours + 5ºC 20 Days 15 Food Safety on Stone FruitsIs there Really a Risk? Potential Sources of Contamination • Preharvest: – Contaminated irrigation or spray water – Presence of animal husbandry – Insects (flies) • Harvest – Contaminated hands, poor employee hygiene – Contaminated harvest tools and containers • Postharvest: – Fruit contact surfaces (packing line, human hands, packaging) – Wash water (hydrocooler, washing, coatings) From: Rodrigo Cifuentes 16 Conclusions Phase 1 • Over 99% of bacteria inoculated over intact skin die within the first 24 hr after inoculation • Wounding apparently provides adequate free moisture and nutrients that favor bacterial survival and multiplication, depending on the storage temperature • Salmonella serotypes tested have different survival capabilities over the intact and wounded skin of peaches Final Conclusions •No effects were observed on bacterial survival between fruit maturities (CA well mature or tree ripe), flesh acidity (yellow or white-fleshed), or between species (peaches, nectarines and plums) •Immediate storage of the fruit after inoculation can significantly enhance bacterial survival over time (wet fruit) •Low temperature and high RH can favor bacterial survival on intact skin, and high temperature (despite RH) favors bacterial multiplication in sub-epidermal wounds •Brushing and coating with waxes can improve bacterial survival over Peach or Nectarine skin (no plums tested) •Brown rot decay (Monilinia fructicola) may enhance Salmonella multiplication when co-inoculated in sub-epidermal wounds 17 Padding in Field Bins and Picking Buckets Reduces Bruising Injury Beth Mitcham Packinghouse Operations Dumping • Automatic bin dumps • Control speed of dumping • Fruit should fall into water, not onto fruit pilled up in the water tank • Reduce the height of fruit drop – fruit can hit the bottom of the water tank • Use care during manual removal of leaves to avoid fruit injury Beth Mitcham Beth Mitcham Packinghouse Operations • Eliminator – Diverging rollers remove undersized fruit Cracking • Cluster Cutter – Singulates fruit to allow for sizing • Sorting – Labor intensive – Removes under-ripe, damaged and decayed fruit – Adequate lighting is important • Cool white fluorescent bulbs • More than 200 lumens – Depends on number, type and height of lights – Measure at table height Cherry Defects Doubles • Install reflectors to avoid glare and eye fatique Beth Mitcham 18 Packinghouse Operations • Hydro-cooling – Shower system • Approximately 8 minutes to cool fruit to near 32º F • Drop height from shower pan ≤ 8 inches – Use screen at 8-inch height or lower to break water fall Shower Hydrocooler – Immersion system • Slower cooling than in shower • Used for fruit already partially cooled • Less potential for damage • Sizing – Diverging roll sizers • Fruit drop to water flumes or belts • Potential for bruising • Wet rollers to reduce friction Beth Mitcham Beth Mitcham Cherry Defects Shoulder Bruises Pitting Thompson and Grant Packinghouse Operations Potential for Cherry Damage • Cluster cutter – Cherries hit pointed tines – Maintain high throughput by controlling belt speed – Lower tines to belt level • Transfer drops onto cleated belts – Use water transfers – Decrease drop heights – Use padding on surfaces, suspended belts • Rough handling – De-leafing operations – Sorting fruit within packed bin or box Thompson and Grant Beth Mitcham 19 Packaging • Box with liner or bag – Loosely closed, solid polybag – Modified atmosphere bag • Consumer bags – Various sizes – Automatic and semi-automatic bagging • Clamshell – Semi-automatic system – Improvements in future – Modified atmospheres Beth Mitcham Beth Mitcham Modified Atmosphere Packaging • Breathable plastic bag • Introduce gas or fruit modifies atmosphere – Produce CO2 and consume O2 – Final concentration depends on amount of fruit and bag permeability Modified Atmosphere Packaging •Injection of gas not required •Twist-tie or Twistzip-closing bags zipworks fine • Benefits – Slows fruit ripening and senescence – Maintains green stem color – Reduces growth of disease organisms Beth Mitcham Beth Mitcham Methyl Bromide Fumigation Methyl Bromide Fumigation • Codling moth on cherries to Japan – Dose, temperature, 2 hour – Ventilation period – 4 hours • Mites and thrips on cherries to Australia – Second fumigation required on 25% • Increases stem browning • May increase fruit pitting Beth Mitcham Beth Mitcham 20 ...
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This note was uploaded on 12/30/2010 for the course POM 212 taught by Professor Kadermitcham during the Spring '05 term at UC Davis.

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