Volatiles: Impacts of Fruit Development, Ethylene, and Storage Environment Jim Mattheis Tree Fruit Research Laboratory Wenatchee, WA, USA
Fruit Quality Appearance Texture Flavor
Flavor Aroma (volatiles) Basic Tastes (sweet, sour, bitter, astringent) Mouthfeel
Apple Fruit Volatiles >300, aldehydes, alcohols, esters cultivar specific harvest maturity ethylene regulated storage environment
Apple Fruit Volatiles Unripe: aldehydes - green, grassy Ripe: esters - fruity, sweet Ester production regulated by ethylene Sensory response varies with compound: concentration doesn t predict aroma
Fruit Volatiles alcohol ester Compound Alcohols: ethanol 2-methyl-1-butanol Esters: ethyl acetate 2-methylbutyl acetate ethyl-2-methylbutyrate Odor Threshold 2,000,000 ug L -1 320 6000 5 0.08 Obenland et al., 2013
Compounds Contributing to Gala Aroma Compound Descriptor Osme Intensity hexyl acetate gala, ripe, pear 12.3 butyl acetate nail polish 9.7 2-methylbutyl acetate solvent 8.6 methyl 2-methylbutyrate sweet fruity 7.4 ethyl 2-methylbutyrate sweet strawberry 7.3 4-allylanisole anise, licorice 6.5 pentyl acetate gala 5.8 hexyl 2-methylbutyrate apple, grapefruit 5.7 butyl 2-methylbutyrate fruity, apple 5.6 Plotto et al., 1998
Delicious volatile production nl kg -1 h -1 (freshly cut grass) (solvent) August September
Delicious volatile compound production ul L -1 nl kg -1 h -1 August September
Factors Impacting Volatile Compound Production Maturity at harvest Ethylene inhibition Storage conditions
Ester and ethylene production at harvest 100 µg or µl L -1 10 1 0.1 Gala esters Gala ethylene Delicious esters Delicious ethylene 0.01 0.001 80 100 120 140 160 180 days after full bloom
Golden Delicious volatiles after harvest Harvest 3 5 6 1 Song and Bangerth, 1996
Golden Delicious volatile and ethylene production Harvest 1 3 5 6 Song and Bangerth, 1996
Volatile Production Maturity at harvest: optimum for condition may not be optimum for aroma production
Volatile Production Storage impacts: low O 2, high CO 2, longer duration decrease production production is dynamic during ripening
Gala ester production after storage 140 µg kg -1 h -1 120 100 80 60 40 O 2 /CO 2 % air 1/1 1/3 3/1 3/3 20 0 60 90 120 days in storage plus 7 days at 20 o C
Gala Volatile Production after Storage air 1 2 3 4 5 6 7 1 2 3 4 5 6 7 months CA low high relative amount
Climacteric Fruit Volatile Production Ethylene Inhibition 1-MCP reduces/delays ripening-related volatile production
Fuji ester production µg kg -1 h -1 1-MCP days at 20 o C after harvest Fan and Mattheis, 1999
Anjou ester production µg kg -1 h -1 1-MCP months in storage Argenta et al, 2003
Anjou ester production control 1-MCP 1-MCP + ethylene 2 4 6 8 2 4 6 8 2 4 6 8 months in storage plus 7 days at 20 o C low relative amount high Argenta et al, 2003
Gala volatile and sensory analysis volatile compound butyl acetate hexyl acetate 2-methylbutylacetate methyl 2-methylbutyrate total esters overall liking (1-9) # and % preferred # and % no preference 1-MCP-RA Control-CA 2.73 9.52 7.33 not detected 34.3 35.4* 39.0* 43.9* 1.96* 203* 1-MCP/CA vrs control CA or new crop Chile: similar preference results 1-MCP-RA Control-CA high volatile production doesn t always = better quality 6.85 93 (50%) 20 (11%) 6.92 73 (39%) 20 (11%) Marin et al., 2009
Honeycrisp Volatile Production After Storage control 1-MCP CA 1-MCP/CA 2 4 6 8 2 4 6 8 2 4 6 8 2 4 6 8 months
Volatile Production During storage low temperature, CA impacts near-real time monitoring for disorders, quality
Scarlet Spur II Red Delicious volatiles during storage % O 2 0.3 0.8 1.6 air 0 4 7 14 25 46 82 110 194 250 0 4 7 14 25 46 82 110 194 250 0 4 7 14 25 46 82 110 194 250 0 4 7 14 25 46 82 110 194 250 days in storage 0 4 7 14 25 46 82 110 194 250
Flavor and Aroma Harvest and storage decisions impact post-storage Low production doesn t always mean poor quality Volatile assessment as a quality management tool
Acknowledgements Dave Buchanan Janie Countryman Luiz Argenta Anne Plotto Xuetong Fan
Gala ester production after storage O 2 /CO 2 µg kg -1 h -1 % days in storage plus 7 days at 68 o F
Gala ester production after storage 140 120 O 2 /CO 2 µg kg -1 h -1 100 80 60 40 air 1/1 1/3 3/1 3/3 % 20 0 60 90 120 days in storage plus 7 days at 20 o C
Gala ester production after storage 140 µg kg -1 h -1 120 100 80 60 40 20 O 2 /CO 2 air 1/1 1/3 3/1 3/3 % 0 60 90 120 days in storage plus 7 days at 68 o F
Fruit Volatiles Hundreds of compounds Different cultivars different amounts Sensory response varies with compound: odor threshold: high concentration doesn t always contribute to aroma
Apple Fruit Volatiles Unripe: aldehydes - green, grassy Ripe: esters - fruity, sweet Ester production regulated by ethylene
Honeycrisp ethyl ester production 3.0 µmol kg -1 l -1 2.5 2.0 1.5 1.0 air SF 1-MCP CA SF/CA 1-MCP/CA 0.5 0.0 2 4 6 8 months in storage