Use of attenuated total reflectance midinfrared for rapid and real-time analysis of compositional parameters in commercial white grape juice.
A simple and fast midinfrared (MIR) spectroscopy method was developed for simultaneously determining total soluble solids (TSS, degrees Brix), pH, total phenolics, ammonia, free amino nitrogen (FAN), and yeast assimilable nitrogen (YAN) contents in grape juice samples using attenuated total reflectance (ATR). Results from this study demonstrated the capability of ATR-MIR coupled with partial least-squares regression to measure TSS and pH and to monitor FAN, ammonia, and YAN in a wide range of grape juice samples. The standard error in cross-validation and the residual predictive deviation obtained were 0.20 degrees Brix and 9 for TSS, 0.07 and 3.3 for pH, 14.8 mg/L and 2 for ammonia, 28.3 mg/L and 2 for FAN, and 36.9 mg/L and 2 for YAN, respectively. Both the time of analysis and the volume of sample required were considerably reduced as compared to the transmission MIR measurements currently used by the wine industry.
Shah
Nevil
N
The Australian Wine Research Institute. Waite Road, Urrbrae, Glen Osmond SA, Australia.
Cynkar
Wies
W
Smith
Paul
P
Cozzolino
Daniel
D
D001628:Beverages / Q000032:analysis*; D013057:Spectrum Analysis / Q000379:methods*; D027843:Vitis / Q000737:chemistry*