30.09.2025

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How Scraped Surface Heat Exchangers Save Tomato Paste from Burning

Imagine peak season: a factory receives dozens of tons of ripe tomatoes every day. The task of technologists is to turn them into concentrated paste with a bright red color and rich taste. But here comes the problem: it is impossible to properly heat thick paste in a conventional plate heat exchanger — it simply stops moving in the channels, overheats, and burns.

 

For exactly these cases, the food industry has been using Scraped Surface Heat Exchangers (SSHE) for decades.

A Classic Problem for Producers

At a factory in Southern Italy a few years ago, technologists faced a typical situation:

  • on the pasteurization line, tomato paste developed dark “burn marks”,
  • the process had to be frequently stopped for cleaning,
  • the color of the finished product lost its brightness, and the taste lost its freshness.

After switching to a scraped surface heat exchanger, the situation changed: the paste heats evenly, no longer sticks to the walls, and the process runs continuously for many hours without interruptions.

 

How a Scraped Surface Heat Exchanger Works

The principle is quite simple:

  • the product moves inside a cylinder with a heating jacket,
  • a rotor with scrapers constantly removes a thin layer of paste from the walls,
  • this prevents burning and creates a turbulent flow of the mass.

As a result, heat is transferred quickly and evenly, even in very viscous products.

 

Process Scheme with SSHE

  1. Feeding concentrated tomato mass from the pre-evaporator.
  2. Gentle heating to pasteurization temperature (e.g., 85–95 °C).
  3. Holding at temperature to eliminate microorganisms.
  4. Cooling to filling temperature to avoid further degradation.
  5. Filling into sterile containers.

Economic Effect

Producers who have implemented scraped surface heat exchangers note:

  • reduction of raw material losses by 2–4 % due to no burning,
  • cleaning time reduced by 30–50 %,
  • continuous line operation increased to 24–48 hours,
  • lower energy consumption thanks to more efficient heat transfer.

 

Benefits for Tomato Paste Production

  • Color preservation – pigments are not destroyed by overheating.
  • Taste without bitterness – no caramelized particles.
  • High productivity – the line runs longer without interruptions.
  • Flexibility – the same unit can be used for sauces, ketchup, purées, or jams.

 

Comparison with Conventional Heat Exchangers

Criterion

Scraped Surface (SSHE)

Plate / Tubular

Product viscosity

Handles thick and sticky products

Limitation: paste cannot move

Burning

Minimal, scrapers clean the surface

High risk of burning

Heating uniformity

Turbulent flow, even temperature

Local hot and cold zones

Hygiene and cleaning

Easy integration into CIP line cleaning

Often requires disassembly

Maintenance

Quick access to internal components

Complex and time-consuming

Another Example

At a Spanish fruit processing plant, one of the lines that previously used a tubular heat exchanger was modernized with an SSHE. The results:

  • cleaning-related downtime cut in half,
  • stable tomato paste color even after long storage,
  • energy savings thanks to more efficient heat transfer.

Such stories are not exceptions but the reality for most producers.

 

As an example of modern equipment, one can mention the Votator® Origin Series by SPX FLOW, designed for handling viscous masses — from tomato paste to jams.

A scraped surface heat exchanger is not just a machine, but the key to stable quality in tomato paste production. It allows manufacturers to avoid burning, preserve the taste and color of the product, and operate with maximum efficiency.