The production of tomato products is an important global industry, with the USA, Italy and Spain being major producing countries. In Spain, there are many small regional producers making tomato concentrates of high quality and thus high added value.

Processed tomato products such as concentrates should be an intense red in colour, and have characteristic tomato flavour and aroma, high consistency and low separation of the liquid fraction. Lycopene is the main component responsible for the red colour and also has positive health benefits due to its antioxidative activity. Colour degradation in tomato products is caused by isomerization, oxidation or enzymic co-oxidation of lycopene.

To help standardize products from small regional producers, it would be useful to identify physical and chemical markers which could be used to monitor properties of the concentrates during their preparation. Some properties used to characterize tomato concentrates, such colour and consistency, are time-consuming and expensive to measure. Thus, markers that can be easily, cost-effectively and quickly determined and that could represent the whole set of variables are more desirable.

A study by Ordonez-Santos et al.¹, investigated 18 physical and chemical variables in 25 samples of commercial tomato products, including crushed tomatoes, tomato puree, tomato paste and heavy concentrates from a range of producers in various countries. Variation and relationships among these variables were analysed by correlation analysis and multidimensional data analysis techniques. Three variables were selected that could be used to classify the sample and monitor quality, namely soluble solids content, the CIE lightness parameter (L*) and total pectic substances content.
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1 Ordonez-Santos, LE; Arbones, E; Vazquez-Oderiz, L; Romero-Rodriguez, A; Gomez, J; Lopez, M (2008). Use of physical and chemical properties of commercial tomato (Lycopersicon esculentum Mill.) products for monitoring their quality. Journal of AOAC International 91 (1) 112-122.

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