The correlation matrix of assessed parameters is presented in
Table 5. There were statistically positive correlations (p < 0.001)
between lightness (L⁄) and total free amino acids, total sugars
and pH. These results confirm that amino acid and sugar contents
have an important role in non-enzymatic browning. However, a
negative correlation was noted between lightness and both HMF
and TA. Orak (2007) found similar results between lightness and
both pH and TA of red grape cultivars. Moreover, there was a positive
correlation (p < 0.001) between HMF and TA. Negative correlations
were noted between HMF and pH, total sugar and total free
amino acid contents.