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Developing a new non-enzymatic method for ammonia in juice and wine

Developing a new non-enzymatic method for ammonia in juice and wine. Peter Mousis Dierberg/Star Lane Vineyard Santa Ynez, CA. Presentation Outline. Yeast Nitrogen Nutrition- a brief overview YANC (FAN)- their role in fermentation

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Developing a new non-enzymatic method for ammonia in juice and wine

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  1. Developing a new non-enzymatic method for ammonia in juice and wine Peter Mousis Dierberg/Star Lane Vineyard Santa Ynez, CA

  2. PresentationOutline • Yeast Nitrogen Nutrition- a brief overview • YANC (FAN)- their role in fermentation • Consequences of under supplementation and over supplementation • Why measure ammonia? • Comparison of existing methods • Development of a new method • Discussion

  3. Yeast Nitrogen Nutrition • Ammonium ion is preferred food of saccharomyces cerevisiae: “candy” • Primary Amino Nitrogen compounds: Arginine, Alanine, Serine, Threonine, etc…, but not Proline or Hydroxyproline • Lower molecular weight peptides

  4. Consequencesofunder supplementation • Sluggish/stuck fermentations • Production of hydrogen sulfide • Increased costs of production/lost productivity • Potential for adverse sensory impacts resulting from lengthening/restart of fermentation process

  5. Consequences of over supplementation • Cell is unable to store excess nitrogen in vacuoles for later use • Perforations in cell membrane due to increased EtOH allow for dangerous increase in H+ concentration to occur • Results in excess arginine, urea, ornithine • Potential for ethyl carbamate • Food for undesirable LAB/spoilage yeasts

  6. Why measure ammonia? • Diagnostic tool to ensure proper nutritional status of incoming grapes • Helps determine if DAP additions are necessary • Legal limit observation • Diagnostic tool post-fermentation

  7. Existing Ammonia Methods • Ion Selective Electrode (ISE) • Enzymatic UV • Formol Titration

  8. A New Method? • Kerouel and Aminot, 1997: “Fluorometric determination of ammonia in sea and estuarine waters by direct segmented flow analysis” • Chemical method, not enzymatic • Selective for ammonium • Sensitive

  9. Method Adaptation • Original method involves fluorescence • Substitution of sulfite for IPB results in the formation of a derivative with OPA reagent • Initial Diode Array Spectrophotometer trials exhibited absorbance peaks at various wavelengths between 200-700nm • Wavelengths were subsequently examined for linear relationship between increasing standard concentration and absorbance

  10. Performance in Wine

  11. Performance in Wine

  12. Performance in Juice

  13. Performance in Juice- ISE

  14. Performance in Juice- ISE

  15. Where do we go from here? • Need for refinement: reagent sensitivity, detection linearity, matrix effects • A more complete assessment needs to be made comparing standard addition recovery of this method to other methods • Cost/benefit analysis- set-up and run time, reagent preparation, shelf life, and ease of disposal- real comparison of various methods’ unique challenges

  16. I would like to thank the following: San Joaquin Valley Winemakers Association

  17. I would like to thank the following: Dr. Barry Gump, CSUF Susan Charlebois, CSUF My colleagues at Dierberg/Star Lane Vineyard

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