ISHS Acta Horticulturae 542: VII International Symposium on the Processing Tomato
EFFECT OF HEAT TREATMENT ON THE PECTINS OF TOMATOES DURING TOMATO PASTE MANUFACTURING |
| Authors: | A. Ciruelos, C. González, A. Latorre, R.M. Ruiz, A. Rodríguez |
| Keywords: | Tomato, concentration, pectins, processing |
| DOI: | 10.17660/ActaHortic.2001.542.22 |
| Abstract:
Pectins are acidic polysaccharides of the plant cell wall that contribute to both the textural and nutritional characteristics of processed foods. During tomato paste processing the tomato fruit is crushed and subjected to an initial heat treatment for the inactivation of the endogenous tomato enzymes that degrade pectic substances; the resulting juice is then exposed to further prolonged heating during concentration. Pectin changes occurring during the manufacture of tomato paste were evaluated on a pilot tomato paste line at different stages: whole tomato fruits, tomato juice, and tomato paste, concentrated to a refractive index of 28/30°Brix. The trial was carried out four times, and the raw material corresponds to two different varieties, grown under the same controlled conditions (soil and agricultural practices) and harvested on close dates to ensure the homogeneity of the tomato intake of the line. The total thermal treatment throughout the process seems to provoke a progressive solubilization of pectin. With regard to the fruit sample, during processing there is an increase in the water-soluble pectic fraction, paralleled by a decrease in the less soluble pectins (oxalate and NaOH-soluble fractions), due to a solubilization of these less soluble fractions. The content of oxalate and NaOH-soluble pectins decreases by around 50%, whereas the content of water-soluble fraction doubles. Thus, the production of tomato paste is accompanied by increased solubilization of wall-bound pectins and pectin polymer breakdown, which confirms the depolymerizing action of severe heat treatments, influencing the final quality of this concentrate in terms of consistency. | |
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