Food drying with superheated steam: Difference between revisions

Revision as of 19:02, 20 February 2011

Super-heated or dry steam has the ability to drive moisture out of solid materials much faster and more cost-effectively than air drying without affecting the color of the end product. This technology is getting a lot of interest in the food industry and could become the frying and drying technology of choice. It is far more cost effective than freeze drying.

It also has advantages in terms of nutrient preservation. There is no free oxygen in superheated steam, so the decomposition of easily oxidized nutrients such as vitamin C is greatly reduced. This is a key advantage over food drying with hot air, which exposes the food to oxygen. (Aside: most people think that it's the heat that destroys nutrients in food, while it's actually the oxygen. This has been shown to be the case with canned food, which often has very good nutrient preservation). Another advantage is that this process is much faster than traditional (solar) food drying, which is crucial when large volumes of one particular crop need to be processed at harvest time (think: tomatoes, strawberries, raspberries - these are all high value products when dried, easily transported, easily traded). By applying lower than normal pressure, it is possible to use temperatures far lower than 100°C, and as low as 45°C for heat-sensitive foods.

Sources of energy (heat) are solar (weather permitting) and biomass, possibly in combination (day/night) for more reliability. When the heat source is pyrolysis (with biochar as a by-product) rather than combustion, the process can be made truly carbon negative, i.e. it actually pulls carbon out of the atmosphere every time you use it.

Examples: Food

sugar: sugar beet pulp, dietary fibre from sugar beet
base materials: hog fuel, corn fibres, protein containing base materials (soy beans, rape seed, sunflower seed, soy meal, okara, etc.)
shrimp, pork, bamboo shoot, paddy/rice, herbs, cacao beans, corn gluten, tobacco (drying, expansion)
starch: starch, wheat flour, distillers grain
meat: pork, bone meal
vegetables & fruit
dairy industry: milk powder, flash drying
potato products, fries (pre-drying)

Examples - other (non-food)

biofuel: drying and grinding of sugary biomass for pre-processing before fermentation
biomass: sawdust, wood fibre, wood chips, wood pulp, spruce and birch bark, milled peat, peat for briquettes
chemical industry: washing powder, pigment, potassium salt, powdery chemicals, catalysts, coloring agents
laundry, dry cleaning
wood, lime mud (before calcination), mineral wool, fibres, cement curing
textile applications (coated) textile, drying
chemical processing - reaction kinetics manipulation
paper, pulp, sludge
Building materials

Links

Paper: Dehydration dynamics of potatoes in superheated steam and hot air

@@ Line 3: / Line 3: @@
 [http://en.wikipedia.org/wiki/Superheated_steam Super-heated or dry steam] has the ability to drive moisture out of solid materials much faster and more cost-effectively than air drying without affecting the color of the end product. This technology is getting a lot of interest in the food industry and could become the frying and drying technology of choice. It is far more cost effective than freeze drying.
-It also has advantages in terms of nutrient preservation. There is no free oxygen in superheated steam, so the decomposition of easily oxidized nutrients such as vitamin C is greatly reduced. This is a key advantage over food drying with hot air, which exposes the food to oxygen. (Aside: most people think that it's the heat that destroys nutrients in food, while it's actually the oxygen. This has been shown to be the case with canned food, which often has very good nutrient preservation). Another advantage is that this process is much faster than traditional (solar) food drying, which is crucial when large volumes of one particular crop need to be processed at harvest time (think: tomatoes, strawberries, raspberries - these are all high value products when dried, easily transported, easily traded). By applying lower than normal pressure, it is possible to use temperatures far lower than 100°Cd, and as low as 45°C for heat-sensitive foods.
+It also has advantages in terms of nutrient preservation. There is no free oxygen in superheated steam, so the decomposition of easily oxidized nutrients such as vitamin C is greatly reduced. This is a key advantage over food drying with hot air, which exposes the food to oxygen. (Aside: most people think that it's the heat that destroys nutrients in food, while it's actually the oxygen. This has been shown to be the case with canned food, which often has very good nutrient preservation). Another advantage is that this process is much faster than traditional (solar) food drying, which is crucial when large volumes of one particular crop need to be processed at harvest time (think: tomatoes, strawberries, raspberries - these are all high value products when dried, easily transported, easily traded). By applying lower than normal pressure, it is possible to use temperatures far lower than 100°C, and as low as 45°C for heat-sensitive foods.
 Sources of energy (heat) are solar (weather permitting) and biomass, possibly in combination (day/night) for more reliability. When the heat source is pyrolysis (with [[biochar]] as a by-product) rather than combustion, the process can be made truly carbon negative, i.e. it actually pulls carbon out of the atmosphere every time you use it.