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Flow injection determination of readily assimilable nitrogen compounds during vinification
J González-Rodriguez1, P Pérez-Juan, M D Luque de Castro
1R&D Department, Pérez Barquero SA, Montilla, Córdoba, Spain.
The Analyst
|May 9, 2002
Summary
A new flow injection method accurately measures readily assimilable nitrogen (r.a.n.) in wine and must. This faster technique quantifies ammonium and aminated nitrogen crucial for biological aging analysis.
Area of Science:
- Analytical Chemistry
- Food and Beverage Science
- Biochemistry
Background:
- Readily assimilable nitrogen (r.a.n.), comprising ammonium and aminated nitrogen, is a critical parameter in winemaking, influencing yeast metabolism and biological aging.
- Accurate and efficient determination of r.a.n. is essential for optimizing fermentation processes and ensuring wine quality.
- Existing methods for r.a.n. determination can be time-consuming or lack the necessary throughput for routine analysis.
Purpose of the Study:
- To develop and validate a rapid flow injection analysis (FIA) method for quantifying readily assimilable nitrogen (r.a.n.) in must and wine.
- To assess the performance characteristics of the proposed method, including detection limits, quantification limits, reproducibility, and repeatability.
- To evaluate the applicability of the FIA method for analyzing real-world samples during biological aging.
Main Methods:
- A flow injection method was designed utilizing the pH-dependent color change of bromothymol blue at 616 nm.
- Formaldehyde was employed to selectively block amino functions, allowing for the differentiation and measurement of ammonium and aminated nitrogen.
- The method relies on monitoring absorbance changes correlated with pH variations in the presence and absence of formaldehyde.
Main Results:
- The developed FIA method achieved detection and quantification limits of 10 and 11.6 mg/L, respectively.
- Excellent reproducibility (3.94 mg/L) and repeatability (1.35 mg/L) were demonstrated.
- The method processed samples at a throughput of 20 samples per hour and showed good correlation with a standard reference method.
Conclusions:
- The proposed flow injection method offers a fast, reliable, and accurate approach for determining readily assimilable nitrogen in must and wine.
- This technique is well-suited for the analysis of samples undergoing biological aging, providing valuable insights into nitrogen dynamics.
- The FIA method presents a significant improvement in speed and efficiency compared to conventional techniques used in routine enological analysis.