Food | Measurement of Tomato Concentrates

Producers of tomato concentrates rely on sugar concentration (°Brix) monitoring to optimize the evaporation process in terms of time and energy consumption. Anton Paar’s inline refractometer L-Rix 5100 has proven well-suited to measure at the inlet and outlet of the evaporation column and to provide data for automated process control.

Concentrates production

Tomato concentrates are made from fresh tomatoes by evaporating water from the juice in order to make it available throughout the year, independent of the season and to reduce costs for storage and transportation.

According to the standard for processed tomato concentrates (Codex Stan 57-1981), one differentiates between “Tomato Puree” (with total soluble solids between 7% and 24 %) and “Tomato Paste” (when the concentrate contains at least 24 % of natural total soluble solids).

Since the tomatoes on average contain 95 % water, the production of concentrates requires a lot of tomatoes. After washing, sorting and trimming, the mature red tomatoes are crushed and preheated, then strained to exclude the majority of skins, seeds and other coarse substances.

The resulting juice is then concentrated to puree or paste using evaporators to decrease the water content.

The most important measure in the evaporation process is the sugar concentration of the juice, which is expressed in % m/m. The inline monitoring of the sugar concentration of both, the product at the inlet of the evaporation column and the concentrate at the outlet, is critical for the optimization of the process and the quality of the final product.

Refractometers have been widely used for many years in the tomatoes processing industry. As the product can be turbid and pulpy, an in-line refractometer is perfectly suited to measure the refractive index and determine the total dissolved solids content of intermediate and final product.

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