Fig. 1

The spectral integral of principal component 6 loading spectrum extracted from long-term treatment application vector normalized first derivative spectral average dataset for the tie chain length trial. Shaded regions can be assigned to: (1) trans fatty acids 968 cm⁻¹, (2) citrate, hippuric acid and acetate 1365 –1160 cm⁻¹, (3) acetate 1419 cm⁻¹, fatty acids and NPN (i.e., urea, ammonium and histamine)1461 cm⁻¹, (4) creatine 1541 cm⁻¹, histamine, hippuric acid, citrate and fatty acids 1576 cm⁻¹, (5) Carboxylic group of free fatty acids ~ 1715 cm⁻¹, (6) C = O stretching vibration of ester linkages of triglycerides ~ 1748 cm⁻¹, (7) CH stretching of fatty acids 3000 –2800 cm⁻¹.