Determination of key volatiles in Australian Black Truffles aroma by combined GCMS and organoleptic techniques

Transcription

1 Determination of key volatiles in Australian Black Truffles aroma by combined GCMS and organoleptic techniques Professor Garry Lee Centre For Forensic Science

2 Support Blue Frog Truffles Flamen Nominee Macenmist

3 Project Summary Three Components 1. Investigation of the quantitative changes in truffle volatiles at different stages of fruiting and development by chemical instrumentation techniques. 2. Sensory Evaluation. This includes the characterisation of the essential aroma qualities of truffles of various quality by truffle experts. 3. Correlate the Sensory and Chemistry using GC- O-MS. Develop a grading scale for Australian black truffles.

4 Project & Future Outcomes 1. Grading Scale for Australian Black Truffle 2. An accurate aroma profile for Australian Black Truffles Used to develop oils Train Dogs 3. Electronic Nose.

5 Why are we doing this? The West Australian, February 15 th, 2011

6 What is it that we desire from a Truffle?

7 Australian New Zealand Standard for Truffles Based on physical and morphological Aspects. Grade A Truffles in this class should be of the highest quality. They should be of regular shape and sufficiently mature to have the characteristic aroma, taste and colour of the species, with only very slight damage. Grade B Truffles in this class may include those that have been damaged or broken but are sufficiently mature to have the characteristic aroma, taste and colour of the species. They may have some shape imperfections and predator damage. It includes truffle pieces greater than 100 g. Grade C Truffles in this class comprise smaller truffle pieces, which have been broken or cut from larger truffles but are sufficiently mature to have the characteristic aroma, taste and colour of the species, but will contain defects and damage marks. Grade D Truffles in this class are immature truffles with little or no aroma and primarily aimed at the manufacturing industries.

8 Australian New Zealand Standard for Truffles Other Provisions. Size Bands: Special (750g +), g, g, g, 0-20g.. Quality Maturity: The aroma must be sufficiently developed and must display satisfactory ripeness for the grade allocated. Minimum Requirements Australian origin, firm, clean, intact, free from pest, damage, foreign visible matter etc. Tolerances

9 UNECE STANDARD FFV-53 Based on physical and morphological Aspects. Extra Class Truffles in this class must be of superior quality. They must be characteristic of the species. They must have a rounded shape, more or less regular and lobed. They must be free from defects, with the exception of very slight superficial defects as well as very slight defects in appearance, shape and colour, provided these do not affect the general appearance of the produce, the quality, the keeping quality and presentation in the package. Class I Truffles in this class must be of good quality. They must be characteristic of the species. The following slight defects, however, may be allowed, provided these do not affect the general appearance of the produce, the quality, the keeping quality and presentation in the package: a slight defect in shape a slight defect in development slight defects in colouring slight superficial bruising. Class II This class includes truffles that do not qualify for inclusion in the higher classes but satisfy the minimum requirements specified above. The following defects may be allowed, provided the truffles retain their essential characteristics as regards the quality, the keeping quality and presentation: defects in shape defects in development defects in colouring superficial bruising slight superficial damages caused by pests provided they are not developing.

10 Which one is the Market Grade?

11 Cost to Industry and Customers Damage to Industry Reputation Industry not getting it s worth in smaller truffles Customers not getting what they paid for

12 Good Quality or Not?

13 Size?

14 Chemical Profile of Truffles Truffles: Western Australia: 3 regions New South Wales: 2 regions Canberra Immature, Mature & Rottten Grade A, B and C (Graded by individual Sources) Received fresh or vacuum packed Stored at 4 C wrapped in paper towel in glass container. Used within 2 days of possession

15 Analytical Methodology Solid Phase Microextraction Varying temperatures. Four different SPME fibres were investigated. Combination of three different stationary phases (divinyl benzene (DVB), carboxen (CAR) and polydimethylsiloxane (PDMS). GC-MS column - polyethylene glycol (AT-wax) stationary phase

16 Analytical Methodology Purge and Trap Solid Sample Truffle subsample was chopped into fine pieces, placed in a 40 ml purge and trap vial, heated to 80 o Cand sparged with helium into a purge and trap concentrator equipped with a Supelco Vocarb 3000 absorbent trap and attached to a GC-MS. Water Extraction 15 ml of water was added to one gram of chopped truffle sample in a 40 ml vial and sonicated prior to sparging with helium. Methanol Extraction One gram of chopped truffle sample was extracted with 10 ml of methanol. 1 ml of this solution was added to 41 ml of water. 5 ml of this solution was then sparged with helium.

17 Results Compound T. melanosporum (Relative % from top 30 peaks) Region 1 Region 1 (1 week old) Region 2 *Literature dimethylsulphide Formic acid, 1 methylethyl ester butanone Butanal, 2 methyl ethanol Formic acid, 1 methylpropyl ester butanol propanol, 2 methyl Butanol, 2 methyl Benzene, methoxy (anisole) Benzene, 1 methoxy 3 methyl *March et al., International Journal of Mass Spectrometry, (2006), p60-67

18 Ethyl Acetate Abundance TIC: T35_610_Acetone_2306.D\ data.ms TIC: T042_Acetone_2306.D\ data.ms TIC: T28_510_Acetone_2306.D\ data.ms Black, Fresh truffle Red, Old truffle (3 weeks) Blue, rotten truffle Time-->

19 Hexanal Abundance Black, Fresh truffle TIC: T35_610W_S.D\data.ms TIC: T042W_S.D\data.ms TIC: T28_510W_S.D\data.ms Red, Old truffle (3 weeks) Blue, rotten truffle Time-->

20 Evolving Volatiles Fresh truffles had relatively fewer peaks = relatively few compounds in its volatile profile. Ageing and decomposing truffles had many compounds and hence many more peaks in their chromatograms. Rotten truffles appeared to be more odorous than the fresher truffles. Fresh truffles had higher concentrations of heavier molecules such as 9,12-octadecanoic acid and its esters. The less fresh and rotten samples had lower concentrations of these heavier fractions, but higher concentrations of smaller, and apparently the decomposition compounds of these heavier molecules.

21 Butanoic Acid Abundance Black, Fresh truffle TIC: T35_610_Acetone_2306.D\ data.ms TIC: T042_Acetone_2306.D\ data.ms TIC: T28_510_Acetone_2306.D\ data.ms Red, Old truffle (3 weeks) Blue, rotten truffle Time-->

22 Preliminary Indicator Compounds Fresh and Healthy Truffles have Higher Concentrations of: 9,12-octadecanoic acid and its esters Ethyl acetate Dimethyl sulphide 2-methyl butanal Acetaldehyde Decomposing and Rotten Truffles have Higher Concentrations of: 2-methyl propionic acid 2,3-butanediol Linoleic acid ethyl ester 3-pentene-2-one 3-hexene-2-one Butanoic acid Propanoic acid Butanoic acid-2-methyl Hexanoic acid-2-methyl Ethanol

23 Chef Sensory Workshop

24 Experts Sensory Workshop

25 Methodology Each participant will be given a sample of green and red bell peppers. Participants are not allowed to discuss their answer with other participants. Open the container given and sniff the bell peppers. Write down the words best describe bell peppers in the description forms provided. Please allow 5 to 10 seconds rest before the next sniff. Each participants will be asked to provide one description that is different from other participants. Discussion and scoring of descriptors Run the test again using truffle sample instead of bell peppers.

26 Results Grade A Truffles Truffle Vote A Vote B Vote C Marks Final Grade Chef Experts Chef Experts Chef Experts Chef Experts Chef Experts B C B B A C B B B C B B B B A A B B A B

27 Results Grade B Truffles Truffle Vote A Vote B Vote C Marks Final Grade Chef Experts Chef Experts Chef Experts Chef Experts Chef Experts B B C C B B A B A B C B B B B B A C C C A B

28 Results Grade C Truffles Truffle Vote A Vote B Vote C Marks Final Grade Chefs Experts Chefs Experts Chefs Experts Chefs Experts Chefs Experts B C A C B C A C B C B B B B A C

29 Results Descriptors, Grade A Truffles Descriptor Additional descriptor Strength Chemical Dark Chocolate 2 methyl butanal caramelized Strong to medium 3 methyl butanal malt Octanoic acid Seaweed Medium dimethylsulfide Earthy Fungus/soil Strong 1 octan 3 ol Musty Medium Yeast Microbiological Medium Mushroom Strong 1 octen 3 one Fruity Fruit cake Weak Formic acid, 1 methyleythl ester Ethyl Butyrate Ethyl 3 methyl butyrate Ground Coffee Woody Weak 5 Methyl 2 phenyl 2 hexenal Shearing shed/damp Wet hay/straw Vegetative Wet rotting leaves Nutty Strong to medium Decanoic acid ethyl ester Fresh tobacco dried vegetative weak Compost Weak Treacle Green/sweet weak hexanal hexanol

30 Results Descriptors, Grade B & C Truffles Ammonia/Pungent Damp/Moist Clay Caramel Dry Mushroom Fungus Cold Roast Meat Sour/Acidic Dark Chocolate Nutty Compost Earthy Musky Grade B Medium Weak Weak Weak Strong Strong Strong to Medium Weak Weak Weak Weak Strong Strong Strong Wet Fur (dog) Rotting Leaves/ Compost Mould Dry Ammonia Musky Yeast Sweet Corn Mushroom Damp Earthy Grade C Weak Weak Medium Weak Strong Weak Medium Weak Weak Weak Weak

31 Sensory Panel Training

32 What next?

33 GC-O Technique Link between sensory data and chemical data Data reduction technique main compounds responsible for sensory stimulus can be separated from other extraneous information Chemical data can be intelligently related to sensory attributes to obtain meaningful data to guide industry and solve complex questions Time Intensity Perceptual Measurement GC/MS output Tenax Trap Voice Recorder Sniff Port GC/MS

34 Volatile and aromagram profiles Abundance 1.25e e e e e+07 1e Ethyl Butyrate O O TIC: LC2E72A.D TIC: CO-72C.D (*) GC/MS profile O N N O HO O Time--> fruity earthy LCB CO Odour Intensity violets caramel Time (mins) Principal aromagram profile

35 Nano-sensor

36 Traditional Gas and Vapour Sensors 1. Traditionally, the active sensing material of gas sensors is based on semiconducting metal oxides 2. Limitations of these sensors include: High operating temperatures Increased energy consumption Relatively large physical dimensions required for sufficient gas adsorption 3. In addition, other materials have been utilised including silicon devices, polymer-carbon black composites and organic materials.

37 Carbon Nanotube High surface area and large aspect ratios Ability to reduce sensor platform dimensions Room temperature sensing potential Low power consumption i.e. cost effective Chemical modification capabilities for increased sensitivity and specificity to target analytes

38 Sensor Testing Facility Dynamic vapour deliver system: Vapour generation from multi-phase analyte (gases, vapours of liquids & solids) Large dynamic vapour concentration range ppt to ppm (analyte dependent) Magnitude of gas analytes & environments Automated time-based command prompts Chemical interference studies humidity, environmental spikes, etc.

39 Acknowledgements Kenny Choo, Honours Student, Curtin University Associate Professor Hanna Williams, Curtin University Al Blakers Manjimup Truffles Harry Eslick Wine and Truffle Company Adam Wilson Great Southern Truffles Damon Boorman Wayne Haslam Blue Frog Truffles Jenna Valentin, University of Western Australia