Freeze drying of microgreens

Growing and drying microgreens is becoming one of the next trends. These are seed sprouts of brassica, leafy or root vegetables and by appearance would tempt to be categorized as herbs.

Compared to herbs, however, microgreens have a little more water and users are more interested in appearance. In fact, there is no requirement to freeze-dry already chopped or finely chopped pieces.

Process time? Forget the vegetables and fruits!

A regular reader of our blog already has some idea how to set up a freeze dryer for a good drying result of 7 - 10 kg of vegetables or fruit. In the case of microgreens, however, we are back to herbs again, where the time required to dry the load is drastically reduced.

This is due both to the lower water content in the chamber of the lyophilizer, but also to the unused space between the individual sprouts, at least if we want to avoid cramming the product onto a tray in order to make the most of the shelf space of the freeze dryer.

Thus, while the usual processes for fruit, vegetables or meat take 30 to 40 hours, in the case of microgreens we are talking about a time of 12 to 18 hours. Of course, this depends on many factors such as the volume of water in the product, the amount of product on the trays and last but not least, the level of drying required for our product.

Capacity will be the main limit

So drying time is interesting, but it is worth adding that, as with drying herbs, capacity will be the main limit in the case of microgreens. The standard 5 shelving systems that AMARU offers certainly do not allow for the usual 7 or even 10 kg of such product. It will depend on how much you want to fill each tray, so that the individual sprouts do not get wrinkled, but let's rather count on a weight of about 3 - 4 kg.

This is where the use of the 7-shelf system comes into play, which has been designed exactly for such products, where the limiting factor is not the water content but the volume itself. If we load the same quantity on 7 shelves instead of five, the process will be even noticeably faster. However, it is more likely that the user will want, in an already short process, to use the area of the additional shelves to increase the capacity of a given loading. Thus, we can talk about a capacity of 4 - 6 kg.

Beware of packing

If we have successfully freeze-dried the microgreens and have reduced the capacity to maintain the nice appearance of the individual sprouts, it would certainly be a shame to break them all now during vacuum packing. However, like most products, freeze-dried sprouts must be protected from ambient moisture.

Packing in a protective atmosphere is suggested, where the durability and quality will certainly be preserved in the best possible way and for the longest possible time. However, for beginners I would suggest to focus on sealing bags or even various air-tight containers, perhaps supplemented with silica gel or an oxygen absorber. This way you avoid increasing the necessary initial investment and can still deliver your perfect product to your customers.