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
- Feeding concentrated tomato mass from the pre-evaporator.
- Gentle heating to pasteurization temperature (e.g., 85–95 °C).
- Holding at temperature to eliminate microorganisms.
- Cooling to filling temperature to avoid further degradation.
- 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.