Seasonality and Flavour

Transcription

1 Seasonality and Flavour Rebecca Smith Valley Produce and University of Reading

2 Herb production in the UK varies throughout the year The season effects factors such as the speed of production (growth of plant) and tendency to early bolting

3 Volatile Compound Profile A Year of Production Fresh herbs harvested at commercial maturity overnight storage at 4 C (Except winter import) prior to analysis by SPME Where possible one variety from one farm location was used throughout the year (science) although this was sympathetic to production needs (commercial reality). Winter import was also included in the analysis although this could be a study in itself! AIM are there any obvious differences that could affect flavour?

4 SPME GC-MS

5 Coriander what we know? Characteristic compounds: Decanal, (E)-2-decenal, nonane, (E)-2-dodecanal, (E)-2-undecenal and dodecanal BUT relative composition is varied Very little analysis of the fresh leaf, usually the extracted essential oil by steam distillation. No literature on seasonality Stress by increasing salinity up to 50mM increases the essential oil yield, higher salinity decreases this below normal Neffati & Marzouk (2008) Storage over 3 days lowers the levels of all volatile compounds (SPME) and aroma (sensory panel) Fan & Sokorai (2002), Loiza (1997)

6 Coriander (E)-2-decenal fatty, green (E)-2-hexenal green, leaf (Z)-3-hexen-1-ol green, leaves (Z)-3-hexenal apple, green Decanal floral, green, soapy Nonane alkane, oily Nonanal fat, citrus, green undecanal waxy, floral-citrus, sweet, fatty 2-dodecenal sweet, fat, green (E)-2-undecenal soapy Dodecanal sweet, waxy, citrus, fatty Month DAS Origin/variety TPA #Compounds DW (%) June 59 days UK cadiz August 45 days UK cadiz October 56 days UK rani January 70 days India ramsey

7 Coriander Compositional Month DAS Origin/variety TPA #Compounds DW (%) June 59 days UK cadiz August 45 days UK cadiz October 56 days UK rani January 70 days India ramsey

8 Flat Parsley What do we know? Characteristic compounds: β-phellandrene, 1,3,8-p-methatriene, myristicin and Myrcene agreement across the literature. No fresh leaf, usually the extracted essential oil by steam distillation. Stress decreasing water availability reduced 1,3,8-p-methatriene and increased myristicin Petropoulous (2008)

9 Flat Parsley P-cymene solvent, gasoline, citrus β-phellandrene mint, turpentine (E)-2-hexenal green, leaf (E)-3-hexen-1-ol green, leaves (Z)-3-hexenal apple, green α-phellandrene spice, mint, turpentine Myrcene balsamic, must, spice P-cymenene Lemon, Fruity, Fuel-like, Sweet, Herbal, Spicy P-menthatriene turpentine myristicin spice, warm, balsamic Pinene pine, turpentine Apiole parsley (faint) Month DAS Origin TPA #Compounds DW(%) June 92 days UK August 85 days UK October 48 days UK January (Mar 2013) Spain

10 Flat Parsley - Compositional Month DAS Origin TPA #Compounds DW(%) June 92 days UK August 85 days UK October 48 days UK January (Mar 2013) Spain

11 Spearmint What do we know? Characteristic compounds: carvone, limonene, 1,8-cineole, Myrcene, dihydrocarvone, carveol Very little on the fresh leaf, usually the extracted essential oil by distillation. Essential oil yield focussed on growth stage, with the highest levels seen during flowering.

12 Spearmint Carvone mint Limonene citrus, fruity β-bourbonene herb 3-octanol mushroom Sabinene wood, pepper, turpentine 1,8-cineole mint, sweet Trans-sabinene hydrate woody, balsamic Bicyclogermacrene wood, green Caryophyllene wood, spicy (E)-2-hexenal green, leaf Month Age Origin (Variety) TPA #Compounds DW(%) June 2011 UK August 2011 UK October 2014 UK January 2012 Spain (Moroccan)

13 Spearmint - compositional Month Age Origin (Variety) TPA #Compounds DW(%) June 2011 UK August 2011 UK October 2014 UK January 2012 Spain (Moroccan)

14 Spearmint compositional (zoom) Month Age Origin (Variety) TPA #Compounds DW(%) June 2011 UK August 2011 UK October 2014 UK January 2012 Spain (Moroccan)

15 Summary Mint Compositions - very little variation over the UK season - autumn higher percentage of some woody compounds Winter varietal difference Higher TPA in summer/autumn compared to spring and even less in winter Parsley groups into spring/summer and autumn/winter with less TPA in the latter Slight increase in the spice/warm compounds and decrease in fruitier/parsley compounds in autumn/winter. Coriander is highly variable! TPA - Summer much higher than other seasons TPA - Winter even lower than spring/autumn Compositional - (E)-2-Decenal peak in the summer with a drop in nonane Compositional - Winter much lower levels of the main coriander compounds (E)-2-decenal and decanal much higher nonane Winter imports have a bigger effect on the TPA of herbs than the UK season is this the extended storage or climate of origin/horticultural practice?

16 UK outdoor herbs appear better than the winter imports!