Evaluation of quality the pumpkin, wild plum, pear, cabbage traditional homemade vinegars using the spectroscopy and rheology methods.

In this study, the quality evaluation of homemade pumpkin, pear, wild plum and cabbage vinegar produced by traditional methods was carried out using the ultraviolet (UV) spectroscopy, rheology technique and Fourier transform infrared (FTIR) spectroscopy method. The measurement of UV spectra, flow behaviours and infrared spectral fingerprints of all the vinegars were performed in the wavelength range of 190 nm to 600 nm, shear rate of 10 s to 10 s and wavenumber of 4200 c to 400 cm at room temperature, respectively. The quality of homemade vinegars was correlated with the UV spectra peaks, which took values with acetic acid and phenolic compound concentrations. It was determined that the absorption coefficient and optical energy gaps (E) which were caused by the release time, depends on the organic acids content. It was observed that the UV spectra and forbidden energy gaps of all the vinegars compatible with the Lambert-Beer-Bouguer and Tauc laws, respectively. The flow behaviour of homemade vinegars was consistent with the non-Newtonian flow, which is the signature behaviour of the dilatant (thickening) and pseudo-plastic (thinning) liquids. Moreover, it was determined that the spectral fingerprint peaks obtained from FTIR spectroscopy were caused by the mixture of acetic acid and water forming the structure of the vinegar. As a result of spectroscopy and rheological analyses, which yields compatible results with commercial tests, it is predicted that it can be safely used as health test.