Microwave and combined drying

Microwave energy heats the moisture inside the product. In production, it can be combined with air flow or vacuum to control water removal.

How it works

Heating occurs in the volume of the product, and the resulting steam must escape. Power, timing and pause times are important: rapid heating is not necessarily uniform.

History

Comparison of continuous and pulsed heating

An experiment with apple slices compared hot air, continuous and intermittent microwave treatment. Speed, color and ability to reabsorb water were assessed.

Combinations with other methods

A 2014 study looked at pre-air-drying apples and then microwaving them under vacuum. Therefore, these names can describe successive stages of one technology.

What changes in the product

Porosity and crunch

Experiments with apple tissue show that the heating mode changes the pores and structure. Swelling is possible, but shrinkage, destruction or burning are also possible; The method does not have a universal texture.

Speed is no substitute for taste

In experiments with apples, microwave modes accelerated the removal of moisture compared to the air drying studied. This benefit cannot be transferred to another grade, size or equipment without verification.

Risk of uneven heating

Local overheating can degrade the product. Pulsed modes and combinations with airflow are being explored as ways to better distribute temperature and moisture.

Pros

• Energy can be supplied directly to the product volume.
• In a suitable mode it is possible to reduce processing.
• The combinations give the manufacturer additional texture control tools.

Limitations

• Unsuitable power creates hot spots.
• The effect depends on the size, composition and moisture content of the raw material.
• The name does not indicate sugar, oil or pre-impregnation.
• The industrial mode cannot be reproduced by one name in a household microwave.

Where is it used?

• Fruit slices studied using apples as an example.
• Combined processes with warm air.
• Combined processes with vacuum.

When to choose

• A specific crispy or porous shape is needed, and you can evaluate the finished sample.
• The supplier describes the entire process, including the preliminary stages.

When to choose another option

• The choice is based only on the promise that faster always means healthier.
• The batch has some burnt bits and significant unevenness.

What to know before buying

• Was the drying microwave, microwave-vacuum or combined?
• What texture is expected after opening and in liquid?
• Was sugar or butter added?
• Is there any data on the composition of the finished product, rather than the raw fruit?