A methodology was developed to study the antioxidant content and activity of tomato products differing in variety and processing. Eleven tomato samples (in duplicate) were assessed for dry matter, color, antioxidant content [e.g., ascorbic acid, total phenolics, and carotenoids (lycopene, β-carotene, lutein)], and antioxidant activity of the hydrophilic and lipophilic fractions. The antioxidant activity was measured by the following modeling systems: (a) xanthine oxidase (XOD)/xanthine system, (b) myeloperoxidase (MPO)/NaCl/H 2O2 system, and (c) linoleic acid/CuSO4 system. These modeling systems simulate the oxidative reactions occurring during the initiation and progression of human disease, thus allowing us to evaluate the potential inhibitory role of tomato products. The Principal Components Analysis (PCA) was used to assess differences between samples. Results showed that all the variables measured significantly explained the differences between samples, except for the antioxidant activity as measured by the MPO/NaCl/H 2O2 system, which was thus removed from the statistical model. The model was then found to be appropriate as the first two components explained a fraction of total variance of the samples equal to 78%. The score plot showed that samples covered a wide area within the first two components, which reflected the variability of the products available on the market. In particular, it was observed that fresh samples were clearly distinguished from processed samples. In the first component (60% explained variance) fresh tomatoes were separated from tomato pulps and tomato pastes, whereas in the second component (18% explained variance) contributed to separation of tomato pulps from the other tomato products. Tomato purees were located closely to either the tomato pastes or the tomato pulps. By overlapping the score plot and the loading plot it was observed that fresh samples were mainly described by high ascorbic acid content, lutein content, and antioxidant activity as measured by the XOD/xanthine system. Tomato pastes were described by high values for lycopene, total phenolics, color, and antioxidant activity as measured by the linoleic acid/CuSO4 system. In conclusion, PCA showed that the variables chosen could discriminate samples according to variety and processing.
|Titolo:||The antioxidant activity of tomato : 1, Evaluation of fresh and processed products by chemical-physical indexes and biochemical models systems through the Principal Component Analysis|
|Settore Scientifico Disciplinare:||Settore AGR/15 - Scienze e Tecnologie Alimentari|
|Data di pubblicazione:||2001|
|Enti collegati al convegno:||International Society for Horticultural Science|
|Appare nelle tipologie:||01 - Articolo su periodico|