HUMIDITY CONTROL
Maintain quality, reduce waste
John Barker, managing director at Humidity Solutions focuses on humidity control in food production and storage.
M
any foods have a tremendously high moisture content, so it is no surprise to hear that if you maintain the water content in a product - whether it be plant based or meat - that it extends shelf life. However, it may be interesting to know how humidity assists the growing, production, harvesting, cooling and storage of plants and other food products, in preparation for the consumer.
Efficient food production, effective storage and extended shelf life all helps to increase food producers’ profits and, crucially in this day and age, also reduces food waste as the product stays in an attractive and edible state for longer. Maintaining quality whilst extending storage time are therefore key issues for all growers to improve productivity and profitability.
Vegetables and brassica
Humidity control is an important factor that needs to be considered for indoor growing of vegetables, and is particularly effective for salad, herbs, baby leaf and brassica. The amount of moisture in the air affects the transpiration rate of plants, which refers to the amount of water
18 March 2021
lost by plants. Transpiration is responsible for moving water and nutrients from the root to other parts of the plant.
However, when humidity levels are too high or too low, transpiration slows and curbs plant growth. The correct humidity level is therefore extremely important, anything outside of this ideal range will cause the stomata to close as a stress-induced response.
Post-harvest
Natural absorption/hydration occurs through the pores or stomata of plants, vegetables and soft fruits. Once picked, produce dries out very quickly in refrigeration. Post-harvest humidity control is therefore essential to maintain the quality of the product once out of the ground or greenhouse. A good solution is to use a tailored package using the latest ultrasonic humidification technology which reduces the dehydration crops suffer whilst in cold storage. The system uses pure water and no chemicals to fill the cold store with a visible fog which will penetrate the crop and re-hydrate it. This natural process is known as the adiabatic effect (evaporative
cooling). Rehydrating the crop maximises pick weight, enhances quality and locks in the natural freshness with just purified water. Maximising pick weight and yield by rehydration this increases or maintains profit margins as most products are sold by weight.
For example, baby leaf, such as perpetual spinach, would normally start to wilt after 2 days in cold storage, depending on weather conditions during harvest. With ultrasonic humidification, growers can leave the product in the conditioning fog for 24 to 48 hours before delivery to the pack house, so that it is able to cool to the desired temperature and fully hydrate. Rather than using other, more harsh cooling methods such as blast chilling, which can damage the leaves, this fogging often means the product emerges in better condition than when first harvested, and may be kept in this condition for up to 11 days, only then will it start to wilt, but no faster than usual. No adverse effect on customer shelf life has been experienced by growers. Moreover, improvements in taste, texture and sugar content have been identified.
Brassicas are being kept in better than ‘as
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