Factors influencing mandarin fruit quality David Obenland, USDA-ARS, Parlier, CA Mary Lu Arpaia, UCR What drives the eating Outline experience in mandarins? Exterior appearance is important for the initial purchase and can have some impact on the perception of taste Flavor quality is even more critical. Consumer acceptance and whether they will buy again.is strongly linked with flavor quality 1
Outline of talk Impact of sugar and acid balance Influence of aroma compounds Off-flavor formation during storage Sensory properties of food related to flavor Flavor Taste Odor/smell/aroma Texture/mouthfeel Temperature Irritation/pain 2
Taste Taste is a sensation that is perceived in the mouth by the tongue Sweet Very important in mandarins Salty Bitter Sour (acidic) Umami (protein savory) Outline In navel oranges sweetness and acidity are described by the California standard California Standard CA Standard = (SSC (TA * 4)) * 16.5 Analysis: Mark Loeffen Delytics Ltd, New Zealand 3
California Standard 50% liking Navels California data California Standard Data from Australia suggests that if a California standard for mandarins is developed the value may need to be higher than that currently set for navels 35% liking Mandarins Australian data Analysis: Mark Loeffen Delytics Ltd, New Zealand Like Extremely 9 The scatter in the individual points (fruit) below indicates that sugar and acid does not entirely determine flavor 8 7 Hedonic Scale 6 5 4 3 2003-2004 2004-2005 2005-2006 2 1 0 2 4 6 8 10 12 14 Brim A Dislike Extremely SSC-(4*TA) Navel orange data 4
Flavor is not just Sugar:Acid.aroma compounds are very important 80-90% of taste is aroma 2% of the human genome is involved in olfactory perception Elizabeth Baldwin USDA/ARS Aroma compounds (Volatiles) Aroma (or smell or odor) is the sensation perceived when volatile compounds are drawn into the nose. These compounds are also perceived by the brain when they travel up the back of the throat. Florence Negre-Zakharov, UC Davis 5
GCMS for aroma volatile analysis Robotic solid phase microextraction system Aroma Analysis and Product Quality Odor descriptors 2-Ethyl hexanol citrus, fresh, floral, 2-Methyl oily, sweet butyl acetate 270,000 ppb banana, candy, citrus 5 ppb Hexyl acetate apple, cherry, floral, pear, wine 2 ppb? Odor thresholds (minimum concentration of a substance at which a majority of test subjects can detect and identify the substance characteristic odor) Florence Negre-Zakharov, UC Davis 6
Many aroma volatiles are present in mandarins and help determine flavor. These below were found to change as a result of storage. Storage time (wks) Compound (µg/l) Gold Nugget (low) Pixie (high) Alcohols 0 3 0 3 Ethanol (mg/l) 359 554* 930 3445* 3 Methylbutanol tr tr tr 75* 2 Methyl 1 butanol tr tr tr 44* Linalool 254 34* 122 60* 4 Terpineol 104 22* 41 24* Esters Ethyl acetate 1753 2922* 487 5812* Ethyl propanoate 92 201* 36 320* Ethyl isobutyrate tr 8* tr 73* Ethyl butanoate 18 37* tr 466* Ethyl 2 methylbutanoate tr 6* tr 209* 3 Methylbutyl acetate tr tr tr 9* 2 Methylbutyl acetate tr tr tr 8* Octyl acetate 256 60* 185 106 Decyl acetate 102 19* 64 34 Ketones 1 Penten 3 one 7 7 6 8* Carvone tr 12* 15 8 Aldehydes Pentanal 9 11* 9 15* Hexanal 20 24 28 19 E 2 Hexenal 27 21 18 47* Heptanal 17 16 15 19 Octanal 179 48* 386 66* E 2 Octenal tr tr 8 6 Nonanal 83 44* 106 47 E 2 Nonenal tr tr tr tr Decanal 529 38* 223 54* Malty, woody, earthy Sweet, fruity Spearmint, caraway Fatty, grassy, green Mandarins often develop off-flavor during storage Not fresh Over ripe Spoiled Strange aftertaste Really old 7
Acceptability Typical mandarin response to cold storage + 1 week at 68F 7.0 6.5 6.0 5.5 5.0 0 1 4 7 Weeks Likeability Off-flavor Tartness W. Murcott 70 65 60 55 50 45 40 Off-flavor/Tartness Some factors influencing off-flavor in mandarins Hedonic score 8 7 6 5 4 3 2 68 F storage 1 41F 0 weeks 2 weeks 4 weeks 0 0 1 2 3 4 5 6 Weeks after packing W. Murcott Warm temps enhance Time in cold storage influences response Some varieties more problematic than others 8
Warm temperature response of other mandarin types China S-9 Okitsu Wasi Hedonic Score 7.0 6.5 6.0 5.5 5.0 4.5 4.0 0 1 3 @ 5 C + 1 Weeks following packing 5 C 20 C 7.0 6.5 6.0 5.5 5.0 4.5 4.0 Hedonic Score 0 1 3 @ 5 C + 1 Weeks following packing 5 C 20 C Fairchild Nova 7.0 6.5 6.0 5.5 5.0 4.5 4.0 Hedonic Score 0 1 3 @ 5 C + 1 Weeks following packing 5 C 20 C 7.0 6.5 6.0 5.5 5.0 4.5 4.0 Hedonic Score 0 1 3 @ 5 C + 1 Weeks following packing 5 C 20 C Harvest date can affect the negative impact of storage on mandarin flavor Lindcove Ojai Early in the season there was less of a flavor difference When the flavor loss occurred it was mainly due to off-flavor Data from Owari satsumas 9
Coatings provide a formidable barrier to gas exchange Waxed Unwaxed O 2 ethanol We assayed for ethanol as an attempt to screen for off-flavor susceptibility Major product of low oxygen and fermentation Substrate for volatile synthesis Ethanol easy to measure Is there variability out there? Bailey-Serres et al., 2012 10
Large varietal differences exist in the amount of ethanol accumulated after waxing and storage Harvest Coating + 68F 1 week Pixie Gold Nugget Response of a high ethanol producer (Pixie) vs. a low ethanol producer (Gold Nugget)to waxing % Internal O 2 25.00 20.00 15.00 10.00 5.00 0.00 0 50 100 Time after waxing (h) GN P EtOH (mg/l) 2000 1800 1600 1400 1200 1000 800 600 400 200 0 0 50 100 Time after waxing (h) GN P After waxing Gold Nugget maintains a higher internal oxygen level and produces less ethanol than does Pixie 11
Passage of gases through the peel occurs more slowly in Pixie than Gold Nugget Ethanol CO 2 O 2 Lowering internal oxygen in the fruit with nitrogen gas leads to a very similar ethanol response for Pixie and Gold Nugget 25.00 2000 1800 20.00 1600 1400 % Internal O2 15.00 10.00 GN P Ethanol (mg/l) 1200 1000 800 600 GN P 5.00 400 200 0.00 0 50 100 0 0 20 40 60 80 100 120 Time (h) Time (h) Ethanol production similar for both varieties in nitrogen gas and suggests an important role for the peel 12
Conclusions The sugar:acid balance is a very important component of mandarin taste Aroma compounds also play a critical role in determining mandarin flavor Loss in flavor quality as a result of storage is common Waxing Temperatures following waxing Time of season Variety Our research has been funded Our joint by the lab California group Citrus UC Research and USDA-ARS Board and the US-IS BARD Program 13
Questions? 14