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FTIR Analysis at Harvest and Fermentation
Gusmer Enterprises May, 2015
by Calvin Watkins Nate Starbard
Contents • Background of FTIR • Overview of FOSS FTIR platforms
• WineScan • OenoFoss
• Applications during vinification, harvest, fermentation • Grape Health / Rot • Ripeness • Crush Pad • Fermentation
What is FTIR? • FTIR is a technology that passes IR light through a sample. • As this passes through the sample, portions light spectrum are absorbed by
the molecules of the sample. What isn’t absorbed is collected as IR interferograms and sent to the computer for analysis.
What is FTIR? • These readings are run through a series of
calculations that then provide a result on the computer monitor.
• FOSS’ robust calibration based on 10’s of thousands of reference analyses and decades of work
WineScan • The WineScan FTIR platform has been performing the bulk of routine wine
analysis for over 20 years (>1100 units in operation) • Most outsourced analytical labs • Major university and research programs • Almost every major corporate winery (some running as many as 15
WineScan units)
WineScan
WineScan • New FT-2 is not the original FT-120
• Pre-package calibrations ready to go out of the box • Building on OenoFoss success Gusmer now
handles WineScan line fully • Additional parameters people have created:
methanol, anthocyanins, succinic acid, port wine parameters, ethyl acetate and more
WineScan Out of the Box
OenoFoss • The OenoFoss is the latest
FTIR based wine analyzer to be introduced by FOSS.
• Approx. 700 units in operation
• The OenoFoss has lower entry costs than the WineScan, no operating costs, and continues to provide fast accurate results.
• Fewer analyses, no creation
Cuvette Space Motor
Opening Lid
Upper Window
Lower Window
Detector Unit IR-Detector
IR-Beam
Benefits of OenoFoss • Analytical Speed –
• 2 minutes per sample per test battery • Accurate and Repeatable Analysis –
• Results guaranteed to be within Foss specifications • Same results regardless of operator
• Uncomplicated • If you can use a pipette you can use an OenoFoss
• No Consumables, Wear Parts
Harvest and Fermentation Specific Applications for FTIR
Platforms
Grape Health • Visual inspection proven to not be accurate to eventual wine quality
when it comes to rot • Glycerol, Gluconic, Volatile Acidity, Ethanol
• Often all must be considered – a high glycerol, for example, with the other parameters low will not cause issues
• Grape soundness indicators/indexes that account for all (sometimes + glu/fru ratio)
• Typical threshold for glycerol, gluconic, ethanol 1 g/L; for VA 0.2 g/L • Studies show that visual % of grape rot is less of an impact to wine than
duration of grape rot • Glycerol and gluconic can vary by up to 400%, based on time of
infection, at the same % rot • Temperature therefore also important
Infections
• Microbes such as botrytis preferential to glucose • Changes in glucose / fructose ratio are an
indication of degree and length of infection
Grape Maturity/Ripeness • Brix should not be the only indication
• Ratio of amino acids to ammonium also an indication of ripeness in parallel with brix
• Nitrogen containing compounds critical to downstream processing and eventual wine quality • Total utilizable N does not
necessarily increase with ripening but easily utilized N from amino acids does increase
• Negative sensory characteristics attributed to unripeness at least partially due to N sources
• Amino acids important for formation of higher alcohols and esters
Phenolics • Folin C in WineScan ; OD 280 in OenoFoss • Why measure total phenols (tannins +
anthocyanins) • Determine optimum time to harvest • Aging potential • Responsible for color and taste
• Wet chemistry (Adams-Harbertson Assay) one of the longest, most difficult procedures
Analysis @ Crush Pad • Avoids totally relying on visual inspection • Quantitative and defined parameters for quality
and thus payment • Extremely accepted in EU (more co-ops)
• Instant results for each unit (bin, truck) of incoming grapes
• Allows for documentation
Fermentation Optimization • Of course you can closely monitor residual
sugar, volatile acidity, tartaric and malic acids • Closely monitor nitrogen compounds
• Addition of nutrients • Effectiveness of and “good stuff” in nutrients
• Correct environment for the dominance of chosen fermentation strain
• Rack the wine off lees sooner
Stuck Fermentations • Yeast assimilable nitrogen, N compounds • Independent glucose and fructose
measurements – not just total RS • Adjust temperature according to analysis • Watch VA (less than 0.6 g/L) for bacteria
infection and ability for yeast re-start • Lysozyme or RO
ML Fermentation • Selection of strain and accompanying nutrients • Important to monitor: acidity, pH, alcohol
• SO2 (WineScan only) • Monitor usage/completion of malic acid
• Pace of ML fermentation before it gets stuck
Value of Ownership • Cost pay back is often enormous
• Smaller wineries reduce outsourced testing fees • Often spend $15-25K/yr on outsourcing before bringing a lab in-house • Shipping time and costs
• Larger wineries become time efficient, reduce spend on chemicals, footprint of lab and other equipment required
• Increased sampling time frame • Increase sampling sizes
• Every barrel vs a sampling (especially barrel ferment) • Instant results
• Stuck fermentations, additions, on the fly adjustments • More knowledge !!