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Jams, Jellies and Preserves: How to Choose the Right Processing Vessel


As consumers focus on healthy lifestyles and opt for natural products, demand for jam, jelly, and preserve products is growing.  Pre-COVID projections for the category called for Compounded Annual Growth Rate (CAGR) through 2025 of 3.6% globally and 2.8% in North America (source: Market Data Forecast), while the impact of COVID is generally expected to drive demand even higher. 


This growth, and the arrival of products featuring less sugar and the use of a wider range of spices, herbs and rare or exotic fruits, is leading some manufacturers to consider modifying, upgrading or adding processing equipment to keep pace. Ultimately, their equipment choices can have a significant effect on their overall operational performance.

Why Vacuum Vessels Dominate the Jam, Jelly and Preserve Processing Landscape

While small commercial quantities of jams, jelly and preserve products can be produced with an open kettle method, where water is boiled off from key fruit or vegetable ingredients, most larger scale operations rely on vacuum vessels.  Vacuum vessels work by placing the product under vacuum conditions to reduce the boiling temperature considerably, as low as 130° depending on the recipe.  The lower boiling temperature is good for product quality – it helps retain the integrity of the ingredients’ solids and prevents burn-on and sugar caramelization – and for production efficiency – it accelerates processing.


Vacuum vessels are highly configurable and can be customized to optimize production for a specific product or line of products.  To gain the most value for their operation, manufacturers looking to replace or upgrade their equipment, or expand their production, should understand the key factors that determine the best vacuum vessel for their needs.

Factors that Affect the Configuration of Your Vacuum Vessel

Vacuum Pan example
  • Desired output is the first consideration, as it will drive all your configuration decisions. Once identified, your output objectives will be used to calculate the size of not only your vacuum vessel, but also the sizes of your pre-mix kettles, boiler, condenser unit, vacuum pump and standardization kettle. These all work in harmony to optimize your production process.

  • The range and characteristics of your products influence the ideal configuration of your vacuum pan. In particular, the solid content of the initial batch – measured in Degrees Brix (°Bx) – and the desired solid content of the end product will determine how much water needs to be removed during processing, which affects decisions on equipment size. Because different products have different starting and ending points, the full range of products you intend to produce in the vacuum vessel must be considered.

  • Steam and water supply data are necessary to properly calculate your equipment configuration. Can your boiler provide enough steam into the jacket to generate the heat required for your output objectives? Is the water supply sufficient to enable the vacuum’s condenser to condense and remove the volume of evaporating steam?

  • Any current equipment intended to be used must either match up to the configuration of the vacuum vessel or be replaced with equipment that can support the desired output. This primarily involves pre-mix and standardization kettles, but can also include boilers, condenser units and vacuum pumps.

  • Physical space constraints can affect your vacuum vessel configuration. Vacuum pan vessels are taller than a typical mixing kettle in order to accommodate the larger beginning batch size, strong boiling and possible foam action, as well as room for the vacuum pump and condenser. So, any space constraints must be considered upfront.

The heightened demand for jams, jellies and preserves may be leading you to evaluate your processing equipment. If so, the more you understand how to optimize equipment to your situation, the better decisions you’ll be able to make and the greater impact you can have on your operation. If you’d like to discuss your situation with a Lee applications engineer contact us. We’re here to help you make the most of your opportunities.


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