Archive for March, 2010


5-Spice Oatmeal Cran-Raisin Cookies with Legume Butter (Dehydrated)

[ Equipment: Food dehydrator or dehydration oven. For more information about the terminology in this recipe, see Low Temperature Baking: A Journey of 3 Paths ].

Recipe revised on Oct. 25, 2010.

In these cookies, the flavors and textures of the oats, legume butter and fruit are accented with the crunch of popcorn or puffed rice and unfied in the perfume of a baker’s 5-spice blend. Warm air baking in a dehydration oven keeps food alive and intense, so that the individual ingredients can be distinguished in the ensemble. The “cran-raisins” in the title refer to a combination of raisins and dried, sweetened cranberries for a bit of sharpness. The cookies leavened with the popcorn have a bold exotic taste. The popcorn scent tickles the mouth on the first bite, but recedes in subsequent bites. The puffed rice cookies (with less spice) are crunchier but more genteel in taste, as the spices operate more in the background. Both are very good, with tea or coffee.

These cookies contain a mix of raw and not-so-raw ingredients. Semi-raw baking preserves the fresh taste and active enzymes of some of the ingredients, while offering the advantage of gently-cooked ingredients with useful culinary properties. Unlike many no-bake cookies, these are also low in calories with a light legume butter binder and a crunchy solid leavener to give the cookies lift. There are (so far) no true raw substitutes, for example, for the popcorn or the puffed rice. The legume butter isn’t raw, but can be made partially raw with a raw nut butter (such as a raw cashew butter) in place of the peanut butter.

I began thinking about these cookies as I was working on my Presto Chango dehydrator. When it was ready for testing, I knew that I would be making some kind of oatmeal and peanut butter cookies. Oatmeal is one of the few grains that can be eaten raw, excluding sprouted grains. It is the main “flour” in countless no-bake cookies and a favored ingredient in raw-cuisine cookies. The basic oatmeal cookie recipe that inspired this recipe was distilled from the dozens and dozens of raw and no-bake oatmeal cookie recipes I found online.

Regular cookies from a high-temperature oven may be crisp or soft, but usually light and crumbly. No-bake and raw cookies are mostly very dense, physically and calorically, because they lack any leavening and because the binder is usually something sticky and viscous (nearly solid) like pureed dried fruit, melted chocolate or caramels, marshmallow creme and peanut butter. These cookies skirt both these shortcomings with a solid leavener and with a legume binder.

A solid leavener is a filler, any ingredient that can be mixed into no-bake cookie dough to add structure and air pockets. Two popular solid leaveners are popcorn and puffed rice cereal, the latter being the main ingredient in the classic Rice Krispies treats. Neither of the fillers is raw or even low-temperature processed, but they are low in calories and low in acrylamides in the amounts given for this recipe. They also provide an interesting texture and crunch. I made these cookies with crushed popcorn and with puffed rice separately, but another interesting option would be a mix of fillers. Puffed rice cannot be made in the home kitchen. Popcorn is easy to make in the microwave, in an electric popper or on the stovetop. I’ve read that an electric hot-air popper is the healthiest way to pop corn.

American markets stock white and yellow popping corn. White corn asserts itself less than the yellow, but in this no-bake recipe, the “corniness” of either color of popcorn stood out too much. One day I stumbled onto the 5-Spice Cookies on Leite’s Culinaria (a sugar cookie with Chinese 5-spice flavoring), and I thought that strong cinnamon-y, licorice-y spice blend could tie the flavors together better than the traditional cinnamon and nutmeg for oatmeal cookies.

At about the same time, I discovered Penzey’s baking spice, with a flavor profile similar to Chinese 5-spice due to the cinnamon and anise seed, yet subtly distinct due to the mace and cardamom. Now, I have never tasted or sampled the Penzey’s product, but I happened to have all the spices (or close substitutes) in my spice bin and created a blend with my own proportions. My version of the baking spice combines 5 spices instead of Penzey’s 4, with cinnamon being the dominant spice, ground star anise replacing the anise seed and a touch of cloves to balance the licorice. Between the Chinese 5-spice and my baking spice, I felt that my baking spice was more complementary to the individual flavors of the cookies, while toning down the powerful presence of the popcorn. The Chinese 5-spice (mine was the Dynasty brand) seemed to muddy the bright cranberries and obscured some of the other flavors. Chinese 5-spice is sold in many formulations, so in a match-up with another brand, the baking spice might not be superior.

Any of these spice blends will work in this recipe, as will the traditional cinnamon and nutmeg, but I highly recommend trying the homemade baking spice unless the actual Penzey’s spice is available. Although the puffed rice does not overpower the other ingredients, I still prefer 1/2 teaspoon of the 5-spice blend with that leavener for cookies with a touch of the exotic.

The legume butter is a low-calorie mix of peanut butter and pureed lima beans or lentils and produces a firmer cookie than the original peanut butter alone. Lentil paste is darker and will darken the cookies as well. Pureed lentils may require extra cooking in a pan on the stove or in a microwave to rid itself of excess moisture. Lentils have a slightly stronger flavor than lima beans. When combined with peanut butter, the peanuts overpower the taste of the beans, however. The recipe makes more bean puree than needed for the legume butter. The extra amount is there to help the operation of the immersion blender or food processor. Leftover bean puree is tasty with a dash of hot sauce. The recipe also makes more legume butter than needed for the cookies. Leftover legume butter can be spread on crackers for a tasty treat.

The liquid sweetener could be any number of options. I tried honey, maple syrup and agave. Of these, I like the honey and maple syrup a little more in these cookies, possibly because they add more flavor. They are bottled in a range of consistencies, so it may be necessary to adjust the amount of sweetener or add drops of water to get a dough that holds its shape. If the dough gets too wet, it will take longer to dehydrate and the moisture could soften the popcorn or puffed rice.

A final caveat: add the popcorn and/or the puffed rice only if the dough will be shaped into cookies and dehydrated immediately. If the solid leavener contacts moisture for too long, it could absorb moisture and soften. Of course, they will be in a dehydration oven for hours, but it’s my experience that the solid leaveners don’t always crispen to the same degree as before.

At about 70 calories each, two of these cookies per serving won’t break a diet.

Makes 8 cookies
-60 to 80 calories/cookie.
-Oven Temperature: 105-110°F/41-43°C in a dehydrator.


  • 1/2 cup rolled oats
  • 1/2 cup crushed white popcorn or puffed rice (see text)
  • 1/4 to 1/2 teaspoon baker’s 5-spice or Chinese 5-spice (see below and see text)
  • pinch of salt
  • 2 tablespoons honey or maple syrup or agave syrup (see text)
  • 2 tablespoons legume butter (see below, see text)
  • 1/2 teaspoons vanilla extract
  • 1 tablespoon raisins
  • 1 tablespoon dried cranberries

Legume Butter (makes about 1/4 cup)

  • 1/2 cup cooked lima beans or lentils
  • 1 to 2 teaspoons sugar
  • 3 tablespoons natural peanut butter

Baker’s 5-Spice (makes about 1-1/2 tablespoons)

  • 2 teaspoons ground cinnamon
  • 1 teaspoon ground mace
  • 1 teaspoon ground star anise
  • 1/2 teaspoon ground cardamom
  • 1/2 teaspoon ground cloves

Baker’s 5-Spice Method:

1. In a small bowl, mix spice ingredients. Store in an airtight container.

Legume Butter Method:

1. Soak dried lima beans overnight. Simmer in water for about an hour until tender. (Note: lentils don’t need soaking and simmer them for about 20 minutes until tender.) Put 1/2 cup of cooked lima beans (or lentils) in a small bowl. Puree with an immersion blender or in a mini food processor until smooth.

2. Check consistency of bean puree. A spoon inserted in the puree should remain standing. (Note: test with a light and inexpensive kitchen spoon, not a fancy and heavy service teaspoon). If the paste is too liquid, dry it in a pan on the stove over low heat or in the microwave. In the microwave, heat for 10-15 seconds, remove and stir to cool, and repeat until done.

3. Put 2 tablespoons of bean paste in a small bowl. Add sugar to taste and mix.

4. Add peanut butter and mix. Cover and store in the refrigerator until ready to use.

Cookie Method:

1. For cookies with a popcorn leavener: It takes about 1 cup of popcorn to make 1/2 cup of crushed popcorn. Crush the popcorn by squishing it between fingers to get pieces about 1/4-inch big. Place in a small bowl and set aside.

2. Optional: for a finer texture cookie, briefly grind oatmeal in a coffee grinder (about 3 or 4 pulses). Oatmeal should still be coarse, not a powder.

3. Combine the 1/2 cup of the ground oats, 5-spice and salt in a bowl. For the popcorn cookies, I recommend 1/2 teaspoon of 5-spice. For the puffed rice cookies, I recommend reducing the 5-spice to 1/4 teaspoon – UNLESS a stronger exotic flavoring is desired.

4. Combine honey (or maple syrup or agave syrup), legume butter and vanilla in a small dish. Add to oats and mix. If the dough is too dry, add drops of water to moisten, but do this judiciously, because a wet dough will soften and possibly collapse the popcorn or puffed rice.

5. Add raisins and cranberries and mix or knead into dough.

6. Add half of the popcorn or puffed rice and GENTLY mix or knead into dough. If too much pressure is applied when incorporating the solid leavener, the grains could be crushed flat or absorb moisture and collapse. The above picture shows the dough with the popcorn leavener.

7. Add remaining popcorn or puffed rice in portions. Check the dough’s adhesion with each portion and stop adding if the dough no longer holds its shape when formed into a small cookie. The above picture shows the dough with the puffed rice leavener.

Steps 8 to 12 prepare the cookies for drying in my Presto Chango dehydrator assembled with a 9-inch heating area. For drying in a commercial food dehydrator, follow the manufacturer’s instructions.

8. Turn an 8-inch cake pan upside down and sprinkle with 2 or 3 drops of water. Press an 8-inch circle of wax paper down over the cake pan to anchor it. Divide the dough in half and divide each half into 4 portions. Form each portion into a 2-inch cookie (actually my cookies measured 1-3/4 inches). The above picture shows cookies with the puffed rice leavener.

9. Slip the dehydration screen under the wax paper and slide the wax paper onto the screen. Center screen over heating area. Finish assembling the dehydrator. Dehydrate at 105-110°F for about 2 hours until top surface is dry. Turn each cookie over and continue dehydrating for another hour or two. The above picture shows cookies with the popcorn leavener.

10. Remove the cookies from the dehydrator and serve, or allow to cool and store in an airtight container. If the cookies soften in storage, put them back in the dehydrator for an hour or two. In the above picture, the two cookies on the left have popcorn leavening, and the ones on the right were made with puffed rice.


Slow-Rise, No-Knead Chinese Steamed Buns

[ Equipment: steamer. For more information about the terminology in this recipe, see Low Temperature Baking: A Journey of 3 Paths ].

Revised: September 24, 2010.

These steamed buns get their tang from the long fermentation of the yeast, like a sourdough, but without the fuss of attending to a starter. The basic dough process comes from the recipe for no-knead bread first reported by Mark Bittman of the New York Times and adapted from a recipe by Jim Lahey of the Sullivan Street Bakery in New York City. When I first read about no-knead bread, I fell into a depression because I did not have a high-temperature (450°F) oven to bake a loaf. At the time, I was making steamed buns with a sourdough starter. It had not occurred to me to use the no-knead dough for buns. Buns are shaped. No-knead bread dough is too wet to be shaped. The loaf is baked free-form in a dutch oven. An internet search back then didn’t turn up any recipes for no-knead rolls either, baked or steamed.

After I moved to a new apartment, I never got round to reconstituting the sourdough starter. I had resolved to make steamed buns the convenient way, with packets of commercial yeast. Before I could tear open a packet, the idea popped into my head: make the buns by steaming the no-knead dough in muffin molds. The shape would not be traditional, but I would have the great flavor from long fermentation. (This idea will work for baked buns or rolls too.) The steamed no-knead buns turned out so well that I now make them at least twice a week.

In Lahey’s original recipe, the proportion of water to flour by weight was almost 1 to 1 (98% hydration). My recipe stays close to that formula, perhaps a little less at 93% hydration. Hydration is important. If the dough is too dry, the buns will be dry. If the dough is too wet, the buns will need more cooking time and excessive exposure to moisture could affect the texture (coarser bread).

The yeast must be fresh. I make a batch of buns at least twice a week and a single packet of active dry or rapid rise yeast can last over a year, sealed and stored in the freezer. However, once the yeast packet (or jar) is opened and exposed to air (especially if the air is humid), the granules will lose potency over time. Buns leavened with weakened yeast may rise very slowly (more than a day) or not rise at all.

The “pinch” of yeast in the ingredients list is just that; no need to measure out any of the granules. For those who want precise measurements, I have had great success with 1/16 teaspoon of yeast granules. Both active dry yeast and rapid rise yeast will work in this recipe. Rapid rise yeast is faster, but active dry yeast is more flavorful (more sour). The first rise for doughs with rapid rise yeast should be from 12 to 18 hours and active dry yeast doughs can go for a full 24 hours. The minimum rise time for either type of dough should be 12 hours to develop the gluten and flavor. I do not recommend longer first rises than specifed, because the dough can take on a yeasty smell and could collapse. Collapsed doughs do poorly in the second rise.

Although the dough contains yeast, it also contains baking powder or baking soda. The purpose of the baking powder or soda is to neutralize acidity (Chinese steamed buns are typically not sour) and give a chewier texture to the finished bun that is characteristic of Chinese steamed buns. They can also boost the second rise, if the reaction hasn’t been exhausted in the first rise. I recommend adding baking powder to doughs with rapid rise yeast and baking soda to doughs with active dry yeast. Active dry yeast doughs tend to be more acidic, and baking soda is excellent at neutralizing the acid.

In some steamed bun recipes, the baking powder or baking soda is kneaded into the dough after the first rise, but I have found that doing so can cause dark streaks in the cooked buns. My experience has been that mixing them into the dry ingredients at the beginning works just as well. If desired, the baking powder or baking soda can be omitted at the expense of a little coarsening in the texture.

Chinese steamed buns can have a variety of fillings from savory to sweet. They can be prepared in any way (steamed, fried, baked, microwaved), so long as they are fully cooked and solid, and can be divided into 6 portions. I give the recipe for my favorite egg filling. It is very simple to make from scratch, especially in the microwave. Although the pictures show a stir-fry vegetable mix (broccoli, snow peas, green beans, peppers, water chestnuts), any chopped vegetable mix should work fine, so long as the egg mixture solidifies when cooked.

The plum-bean paste filling is the same one in my mooncake recipe and must be doubled to make 6 buns.
The mini sausages in the pictures are Vienna sausages from a can. They measured just under 2 inches and fit perfectly in the muffin molds. Any other COOKED sausage of similar size should be a good substitute. Other tasty fillings include: small meatballs, vegetarian protein nuggets and sweet pastes (like peanut butter or red bean paste).

The muffin molds in the pictures were part of a silicone muffin pan. The original pan was too large to fit in my steamer, so I cut the cups out individually with scissors. Each muffin cup can has a 1/2 cup capacity. Small teacups should work too, if they will fit in the steamer. For larger buns, try putting the dough in 3/4-cup-capacity mini loaf pans.

Makes 6 buns

– 150 calories per bun with egg filling
– Oven Temperature: steaming

Bun Dough:

  • 1-1/2 cups all purpose flour (7.5 oz)
  • 1/8 teaspoon salt
  • 1 pinch active dry yeast or rapid rise yeast
  • 3/4 to 1 cup warm water (see text)
  • 1/2 teaspoon double acting baking powder or 1/8 teaspoon baking soda (optional, see text)
  • 1 recipe egg filling (below) or 2 recipes plum-bean paste or 6 mini sausages (see text)

Egg Filling:

  • 6 potato nuggets (such as Ore-Ida Tater Tots) or cooked bite-size potatoes
  • 1 large egg
  • 1/8 cup water
  • 1/4 cup chopped stir-fry vegetables (see text)
  • 1/4 teaspoon salt
  • 1/8 teaspoon chili powder

Egg Filling Method:

1. Evenly arrange potato nuggets or cooked potatoes in a small bowl. The potatoes will later serve as markers for dividing the filling.

2. In a measuring cup, whisk egg, salt, chili powder and water until frothy. Add chopped vegetables to reach the 1/2 cup mark and mix.

3. Pour egg mixture over potatoes.

4. Microwave, bake or steam the filling until cooked. Cool. Slice the filling into 6 wedges.

Buns Method:

1. In a bowl, whisk flour, salt, yeast and the optional baking powder (for rapid rise yeast) or baking soda (for active dry yeast) until well combined. Although the recipe lists the weight of the flour, the actual amount of flour is less important than the hydration (see text above and steps 3 and 4 below). I used a 2-quart plastic bowl with a lid. This bowl has straight, almost perpendicular sides, which can be marked to measure the rising height of the dough.

2. Mix 3/4 cup of warm water into flour to form a sticky dough.

3. Then add rest of water, 1 tablespoon at a time, to form a wet dough that can be easily spread out with the back of a spoon. For 7.5 oz of flour, I mixed in a total of 7/8 cup water (3/4 cup plus 2 tablespoons). Dough that is too dry will produce dry buns. Dough that is too wet will have a coarse texture. If the dough is adequately hydrated, it should have a slightly wet sheen.

In the picture above, I spread the dough out to cover the bottom of the bowl, so that it will be easier to determine when the dough has risen double height.

4. Cover the bowl and set in a warm place to rise until at least double height. With rapid rise yeast, I recommend a rise time between 12 and 18 hours. With active dry yeast, I recommend a rise time of 12 to 24 hours.

As I said in step 3, the hydration level of the dough is important to get moist, fluffy buns. The dough’s moistness can be judged from the bubbles in the risen dough. In the picture above, the top bowl contains dough that is too dry. The bubbles are bigger and more concentrated in the lower half of the dough. The dough in the bottom bowl is correctly hydrated and the bubbles are smaller and evenly distributed throughout the dough.

5. When the first rise is done, deflate the dough by gently stirring it with a spoon a few times.

6. Grease 6 muffin cups or molds. The muffin cups should be 1/2 cup capacity.

7. Half of the dough will line the bottom of the muffin cups. Dip a spoon in warm water and scoop a rounded tablespoon of dough into each cup to start and add more dough until all cups have about a 1/4 inch layer. The warm water stops the dough from sticking to the spoon.

8. Press or spoon a portion of the filling into center of each mold. The picture above shows 3 types of filling: egg, plum-bean paste and mini sausages. For the plum-bean paste, I deposited 1 tablespoon of paste per bun.

9. Cover the fillings with the remaining dough. Holding a spoon in each hand (or fork or butter knife), press and pull the dough in each mold until the top layer completely covers the filling and is merged with the bottom layer (it doesn’t have to be perfect; some filling can show through).

12. Put the molds in a deep pan or bowl and cover. Place in a warm area and let rise until higher than top of mold (no more than 2 hours if the filling is perishable). I do the second rising in the steamer over WARM water with the heat turned OFF. The water vapor helps the dough stay moist.

13. Bring steamer water to a rolling boil, reduce to a medium boil and steam the buns for 15 minutes. If the buns were risen in the steamer (as I like to do), remove them before boiling the water and put them back in when the water is boiling. When ready the buns should spring back when lightly pressed.

14. Cool the buns in the molds for 10 minutes. Unmold and continue cooling on a rack. If they are not eaten within a few hours, put buns in a plastic bag and refrigerate or freeze.

Below are pictures of the buns with the different fillings: egg, plum-bean paste and sausage.


Presto Chango: Turn A Slow Cooker Into A Stacking Dehydrator (w/ Apple Chips Recipe)

Revised: Nov. 11, 2010


    I. How It Works
    II. Assembly
    III. Testing The Stacked Dehydrator
    IV. Operation
    V. An Idea For Active Convection
    VI. Apple Chips Recipe

The picture above shows two versions of my slow-cooker-powered food dehydrator. On the left is a single-tray dehydrator; the configuration on the right stacks trays in a 2-tier and could be expanded further. The heat source for both is a small 1.5-quart slow cooker (larger sizes can be adapted to the design). Those little gray boxes next to the cookers are DIY temperature controls (not absolutely necessary, except in some types of operation). They constrain the cookers to output a low steady heat. All of the other components are standard kitchen bakeware and accessories, and some of them could be fabricated from poster board or corrugated cardboard to cut costs. A stacked dehydrator could be assembled from scratch for less than $30, including a new cooker and the homemade temperature control. In the last section of this article is a recipe for apple chips, dried in the stacked dehydrator.

On VaporBaker, recipes refer to food dehydrators as dehydration ovens, because the word “oven” suggests a greater transformation in the food as the result of exposure to the low heat – it’s baking with warm air. For example, rehydrated raisins do not turn back into grapes. Beyond camping food favorites like beef jerky and fruit roll-ups, dehydration ovens can produce a wide range bakery-style goods: from cookies to cakes to breads, although the preparation can be distinct to this type of baking. In some VaporBaker recipes, food must be baked in two (or more) stages with one of those stages being in a dehydration oven.

The aforementioned DIY temperature control is not a thermostat. A thermostat cycles (turns on and off) the heating element to keep the dehydrator within a set temperature range. The temperature control doesn’t cycle. It tunes the slow cooker to output steady continuous heat, although the temperature can drift.

Without a temperature control (or a thermostat), a slow cooker must be manually adjusted frequently to steady the temperature, or it will begin cooking the food. Less than an hour after being turned on, a basic cooker on the LOW setting can burn close to 300°F/149°C, way too hot to dehydrate food. Raw foodists say that food dehydrators should operate in the range of 105-120°F (40-49°C), because higher temperatures destroy the nutritional vitamins and enzymes in raw foods. There are other ways, though, to moderate a cooker’s temperature rise so that the dehydrators in this project can be built without a temperature control, if desired.

The dehydrators in this project can easily reach 120°F/49°C, which will safely dry all foods except meat. Meat that may be contaminated with salmonella or other pathogenic bacteria must first be heated to the sterilizing temperature of 160°F/71°C (165°F/74°C for chicken) and then dried at 130-140°F/54-60°C. The single tray dehydrator is suitable for drying meat. In the stacked configuration, the bottom tray can reach 140°F/60°C, but the top tray will be cooler – how much cooler depends on several factors such as the room temperature, which parts are metal (and therefore lose heat), the distance between the trays. Unless it is clear that a system can handle these heating requirements, I recommend dehydrating meat either inside the actual crock of a large slow cooker with a temperature control or in a commercial dehydrator.

I. How It Works:

These dehydrators operate with convection heat. Heat flows upward from the cooker, spreads out from the heat distributor, up through drying trays and out through the venting cover, carrying moisture with it. The above diagram shows the assembly of a 2-tier dehydrator. A 1-tier setup is minus the separator and second drying tray. Add more tiers by stacking separators and drying trays.

The components are standard kitchenware. All the pans should have the same diameter except that the heat distributor pan can be a little smaller (up to 1 inch) than the others to allow air to enter the bottom of the dehydrator and stoke the air flow upwards. Too much smaller and the gap would let in cold air that would adversely affect the dehydrator’s operation.

My dehydrators were built with 9-inch pans. I think I could have enlarged the dehydrators up to 10 inches. Keep in mind that for a given-size cooker, the larger the dehydrator diameter, the lower the internal temperature will be, because of the larger volume of air that the cooker has to heat. A 4-quart cooker with a crock diameter of, say, 8 or 9 inches might be able to heat a larger dehydrator, in terms of tray size and number of trays.

At the bottom is the heat source, a small slow cooker. The pictures show a 1.5-quart cooker with a 7-1/2 inch diameter ceramic crock and base unit (the base unit has been plugged into a temperature control). The cooker can function as a heat source with or without the crock. Without the crock, the dehydrator heats up faster and hotter, and the temperature fluctuates more with changes in ambient temperature. Thus, when the cooker’s base heats the dehydrator directly, the cooker MUST be connected to a temperature control to stabilize the temperature. Direct heating also doesn’t produce water vapor that could impact the dehydration process as vapor heating does.

In vapor heating, the base unit heats a water-filled crock, which then heats the dehydrator. The dehydrator heats up slowly, the temperature is more stable and the water limits the maximum temperature. The water vapor conducts heat to the distributor more efficiently than air. It also helps stabilize the temperature inside the dehydrator and limits the maximum temperature to the boiling point of water (212°F/100°C). I did try operating the dehydrator with the crock empty. Then, the dehydrator heated up VERY slowly. After an hour, the top tray had not reached 90°F.

The heat distributor spreads the heat energy out to maximize the drying area and catches any drips from the drying trays. In my configurations, the distributors are 9-inch metal cake or pie pans. The pans must completely cover and sit flat on the cooker’s base unit or on the crock to maximize heat transfer and, in the case of a vapor-heated dehydrator, to prevent water vapor escaping from the crock. Sometimes, drops of water will occasionally condense at points where the crock and heat distributor pan meet and drip down the sides of the base unit. So long as the drops are few and don’t seem to be affecting the dehydration, I merely wipe them up with a sponge. Larger puddles should be dealt with either by reducing the heat or by placing a heat-proof gasket between the crock rim and the heat distributor pan.

The drying trays are metal splatter screens I got in the bakeware aisle of a local market. They cost less than $5 US each (less than $4 when on sale) and were 11 inches in diameter. I’ve seen them as large as 14 inches. In general, the splatter screens must be larger than the diameter of the heat distributor (eg, larger than the cake pan). Heat from the distributor radiates upward through the mesh and around the food, taking moisture with it. Other fine mesh products could substitute, including screen-door mesh or needlepoint canvas mounted in a cardboard frame. However, splatter screens are already food safe and heat safe.

The separator forms the drying chamber over the first drying tray and holds the drying trays apart. In my 2-tier dehydrator, the band from a 9-inch springform pan serves as a separator. It stands at about 2-1/2 inches tall, which is a bit too high, in my opinion for the majority of foods. The drying temperature drops as the distance between the heat distributor increases. Plus, the metal band itself loses heat. A 1-inch or 1-1/2 band from, for example, a cake pan with removable bottom would reduce the temperature differential and still fit most of the foods that I dehydrate. Lining it with craft foam (sold in 2mm thick sheets) or even plastic food wrap as insulation would reduce it more.

In my 2-tier dehydrator without any insulation, the temperature at the top tray ranges between 15 to 20 degrees (F) cooler than the temperature at the bottom tray. However, when I line the separator with plastic wrap, the temperature differential narrows to 8 to 10 degrees (F). Separators don’t need to be metal though. A strip of thick cardboard taped or stapled into a ring would be fine as a separator, and thick cardboard or corrugated cardboard is a better insulator than bare metal.

The venting cover forms the drying chamber for the top drying tray, but also must allow the water vapor to exit the dehydrator. Stacking another separator ring and topping it with a perforated pizza pan could work (a splatter screen might be too open). If the perforations vent too much, block off some of the holes (with a rolled up kitchen towel, for example) to help build up the heat in the top level. In fact, since it won’t be holding food, the vent could be a disk of perforated cardboard, cut to fit on the separator. Cardboard also insulates better than metal.

I turned my 9-inch stainless steamer insert upside-down to serve as a 1-piece venting cover. However, the insert is bare stainless steel and 4 inches tall. That large, uninsulated volume contributes to the temperature difference between the top and bottom trays. It would have been a better venting cover if the insert had been only 2 inches tall and lined with insulation like craft foam or plastic wrap. However, the extra space is much appreciated for rising bread dough in the dehydrator.

An inexpensive analog probe thermometer stuck through a hole in the top continuously monitors the dehydrator’s temperature. The thermometer is accurate only for the top level; the temperature for the bottom tray must be extrapolated (as explained later).

II. Assembly:

The following instructions apply to the 2-tier dehydrator. For the 1-tier, omit steps 6 and 7.

Parts For 9-Inch Stacking Dehydrator As Shown (see text for substitutions):

  • 1 1.5-quart ROUND slow cooker (if used, the crock having flat top surface)
  • 1 metal cake or pie pan, 9-inch top diameter and bottom large enough to cover the crock or base unit
  • 1 springform or removable bottom pan, 9 x 2-1/2 inches
  • 2 metal splatter screens, 11-inch diameter
  • 1 steamer insert, 9 inch diameter, 2 to 4 inches tall
  • 1 analog instant-read thermometer (0-220°F)
  • wax paper for the tray liners
  • plastic wrap for insulation, if necessary

To Assemble:

A Note About Insulation: I recommend insulating the inside walls of the separators and venting cover for the best heat retention, especially if they are made of metal. The easiest way to do this is to line the insides of each of those components with plastic wrap. I have found that insulating the separator alone in my setup (see picture above) can reduce the temperature difference between trays by 10°F.

The dehydrator will operate fine without insulation even if all the parts are made of metal. In the case of an uninsulated stacked dehydrator, I recommend swapping the trays every few hours so that all the food is exposed to the same amount of heat.

1. Heat source option 1 – base unit direct heating: Remove the crock to heat the dehydrator from the cooker’s base unit directly. Skip step 2. With this option, the cooker’s base unit MUST be connected to a temperature control.

Heat source option 2 – vapor heating: Fill the cooker’s crock with 1/4 to 1 inch of water. Less water generates a higher temperature, but risks running the crock dry sooner, if there are any leaks in the seam between the crock and the heat distributor pan.

2. Optional for vapor heating: During testing, if significant amounts of water and water vapor appear to be leaking from the seam between the crock and the heat distributor, try turning down the heat to reduce the steam pressure inside the crock. If that fails, try placing a gasket between the top of the crock and the heat distributor. The gasket can be cut from a heat-resistant material such as a foam or rubber sheet.

In the picture above, the blue gasket is shown only as an example. My setup does not leak significantly so I have NOT actually tested the gasket with the cooker turned on.

3. Center the heat distributor (cake or pie pan) on the cooker’s base or on the crock’s rim or optional gasket. If desired, place shims of aluminum foil along top edge of pan to enhance the air flow into the dehydrator (see text above). My testing suggests that the shims are not absolutely necessary.

4. Put a drying tray (splatter shield) on top of the heat distributor and center it.

5. Put the separator (band of the springform pan or removable-bottom pan or a substitute) on the drying tray and center it (take out the bottom first).

6. Place the second drying tray (splatter shield) over the separator and center.

7. Put the venting cover (inverted steamer insert) on the second drying tray and center.

8. Insert thermometer through an opening in the venting cover. In the above picture, a rolled up kitchen towel blocks air holes to maintain the temperature in the top section. The strongest heat flow is along the sides, so the towel is arranged on the cover to block air from the outside inward. Do not block all the vent holes.

III. Testing The Stacked Dehydrator:

Set the dehydrator in a draft-free area. In my stacked setup with an insulated separator, there is an 8 to 10 degree temperature difference between the second and first drying trays. The upper tray is always cooler. I recommend testing the temperature difference in any stacked setup as follows.

1. Assemble the dehydrator, including the separator. Rest the probe of a digital thermometer on the first drying tray, at or near the center. A curved probe works best. A digital thermometer probe will give the most accurate reading because they measure the temperature close to the tip of the probe, where the sensor is located.

2. Complete the assembly of the dehydrator. Turn on the cooker to HIGH and monitor the temperature on the bottom probe thermometer until it reaches 120°F (49°C).

3. Turn the cooker to WARM until the temperature stabilizes for at least 10 minutes. Record the temperatures in both thermometers.

4. In use, the actual temperature differential may vary with the type and amount of food being dried. It may be helpful to run this test one or two more times with the trays filled with food.

IV. Operation:

1. In a stacked dehydrator, the top tray is always cooler than the lower or bottom tray. If the temperature difference is known, then add that number onto the reading to get the temperature in the bottom tray. Drying at a lower temperature does less harm to nutrients in food, so the temperature of the bottom tray should take precedence.

2. Assemble the dehydrator up to the first drying tray or if the dehydrator is already assembled, disassemble it down to the first drying tray.

If the food is liquid or very wet like a granola or fruit leather paste, place a liner on the drying tray and center it. Then pour or arrange the food on the liner. Other foods may not require the trays be lined and will dehydrate faster without a liner. When arranging food on a tray, leave a 1/2 space along the edge so that the heat can flow upward. Solid foods can be placed close together, but try not to let them overlap too much. Some items, like cookie dough, shouldn’t touch at all.

3. If the second level is needed, assemble the separator and second drying tray. Then place the food on the drying tray as in step 2.

4. Complete assembly of the dehydrator.

5. Set the heat selector on the cooker to “HIGH” and the temperature control (if used) should be set to maximum.

6. Monitor the thermometer until it reaches about 10°F/5°C below the target temperature (in the stacked dehydrator, estimate the temperature of the bottom tray, which is warmer). Stabilize the heat by adjusting the temperature control (see How to Make and Use a Slow Cooker Temperature Control) or by alternately switching the cooker’s heat selector between “LOW” and “WARM”.

The temperature control steadies the heat more precisely than manually adjustments of the cooker’s heat selector. With a temperature control, the dehydrator can run overnight without being monitored. For overnight operation, first stabilize the heat so that temperature stands still or drifts barely 1 degree over the course of an hour. Then turn temperature control down a little. The system will cool a little, but continue to operate with a higher heat safety margin.

7. Halfway through the drying process, swap the top and bottom trays, so that they are exposed to the same amount of heat overall.

8. Check for water vapor leaks on the crock rim. The vapor may condense into water drops and slide down the side of the cooker. Sponge up any water collected at the base of the cooker. Turning down the heat may stop the leaks. Otherwise, installing a gasket between the crock and the heat distributor may seal the leaks.

V. An Idea For Active Convection:

The dehydrator in this project operates on the principle of passive convection. Heat rises from the bottom of the dehydrator and carries moisture with it up and out the vent at the top. In active convection, a fan accelerates the flow of hot air and the rate of dehydration. In other words, foods dry faster.

It’s not practical to install a fan inside this type of make-shift dehydrator, but another idea is to set the fan on top of the venting cover and angle it so that it blows ACROSS (not into) or UP AND AWAY FROM the vent holes. If it blows across the vent holes, the slight pressure difference will draw air up from inside the dehydrator, like smoke pulled up a chimney by the wind. If it blows up, the fan will suck moist air from the dehydrator directly.

I haven’t tried active convection on my dehydrator, because I don’t have the fan yet. One of those small computer fans might be ideal for this application. The fan should be set on low and blow a very gentle breeze. If the breeze is too strong, the temperatures inside the dehydrator could fall fast.

VI. Apple Chips Recipe:

Apple slices dehydrate in a few hours, much less time than, say, blueberries, which, even when cut in half, will take at least a full day. They are one of my favorite snacks, and very inexpensive if made at home. Other recipes sprinkle them with cinnamon (or other spices) and powdered sugar before dehydrating. I like them plain.

In the pictures, the slices are from a large apple. I arranged them in a spoke pattern for the pictures and could barely fit 10 slices to a tray. That was not the most efficient arrangement. If I had placed the slices in concentric circles, like a bulls-eye, or if I had cut the tray liner with a smaller center hole (nearly 2 inches in diameter in the pictures), I would have been able to fit more. The chips shrink as they dry, so a little overlap is not a problem either.

Makes 20 to 40 chips (depending on apple size and slice thickness)

– 3 to 6 calories per chip
– Oven Temperature: 105-120°F (40-49°C)


  • 1 medium to large apple
  • 1 cup water
  • 2 teaspoons lemon or lime juice
  • Method:

    1. Assemble dehydrator to level of first drying tray. Center a liner of wax or parchment paper (not aluminum foil) on the drying tray.

    2. Mix water and lemon juice in a small bowl.

    3. Wash and quarter the apple. Cut out the core and seeds from each quarter. Slice each quarter into 1/8″ slices and soak them for 10 minutes.

    4. Arrange half of the apple slices on the drying tray. Try different arrangements to squeeze more slices onto the tray. If they won’t all fit, then the remainder may have to dehydrate in a second batch.

    5. Assemble the second drying tray and arrange the remaining slices.

    6. Dehydrate at 120°F/49°C, measured at the bottom tray, for 3 hours. On my setup, assuming a 15°F difference between trays, the probe thermometer at the top should read about 105°F. Swap top and bottom trays. If desired, turn chips over to speed drying.

    7. Continue dehydrating for another 3 hours or until chips are at desired crispness.

    8. Remove chips from dehydrator and store in an airtight container.


    Apple Madeleines (Baked & Steamed)

    May 21, 2010: This recipe has been revised. See the genoise discussion in the Chocolate Gotta-Have-Heart Cake for details.

    [ Equipment: slow cooker, oven or steamer. For more information about the terminology in this recipe, see Low Temperature Baking: A Journey of 3 Paths ].

    March 11 is Johnny Appleseed Day. Johnny Appleseed (aka John Chapman) traveled the American frontier in the early half of the 19th century, planting apple seeds as went. He was a nurseryman, a conservationist, who cared deeply for the land and the creatures living on it. To celebrate Johnny Appleseed Day, I made a remembrance cake, the madeleine, a French tea cake, the taste of which triggered an epic trip down memory lane in Marcel Proust’s novel “A La Recherche Du Temps Perdu” (In Search of Lost Time). I gave the cake an American inflection by infusing it with quinessentially American flavorings: maple syrup, peanuts and (of course) apples, and by shaping it in outline as an apple. In accord with cooking methods of that time, I created both slow-baked and steamed madeleines.

    The classic madeleine is made from a Genoise or sponge batter with an egg foam leavener. I have made a few Genoise batters, and I can’t imagine doing it without an electric mixer. Egg foam is nothing more than eggs whipped until they’re thick with air bubbles. Genoise cakes baked at low temperatures may not rise very much, because the cake may set before the air bubbles can fully expand and lift the batter. If the egg foam batter was saturated with air bubbles, the cake will still be very light. Baking powder could boost the rise, but is a form of cheating to baking purists in this type of cake.

    The base recipe is Jacques Torres’ Classic Genoise. From that starting point, I reduced the proportion of flour to liquid to lighten the load for the egg foam. I substituted the cake flour in the original recipe with all-purpose flour and cornstarch, totalling 1/4 cup. For a denser cake, add more flour and cut back equally on the cornstarch. Butter is a significant ingredient in many genoise recipes (up to a ratio of 1/2 cup of butter per cup of flour), so I introduced a little butter into the Torres batter for flavor without too much fat. The individual egg yolks and honey were replaced with applesauce, maple syrup and yogurt for flavor and to give the cake moistness. The finely ground peanuts stand in for the almond essences in traditional madeleines.

    These madeleines can be steamed or baked. In the steamed cake, the delicate apple and maple flavors are distinguishable and the cake has a firm, chewy texture. However, the caramelization on the baked cake intensifies the sweetness and melds the apple and maple flavors. The baked cake has a firm interior with a crunchier surface and sides.

    In the above pictures, the madeleine on the left was dry-steamed in an aluminum foil pouch. The squished look was achieved by pressing the sides of the foil pouch inward, thereby distorting the silicone mold. The cake on the right was slow-baked. Although baking occurs at a higher temperature, steaming heats the batter faster, so that the outer portion of the cake solidifies while the inner continues to rise. Thus, the baked madeleine has a flat top from even rising, but the steamed madeleine has a convex top or a hump, like madeleines baked at high temperatures.

    Genoise cakes have a drier texture than other cake types. One way to add moistness is to soak the cakes in a syrup after baking. Madeleines are somewhere between a cake and a cookie, and can be enjoyed without syrupy enhancement. Served while warm, these apple madeleines are soft and light and dissolve quickly in the mouth, leaving behind just a few grains of peanuts. Cakes that have been sitting out too long can be restored by putting them in the microwave for 15-20 seconds.

    Makes 4 apple madeleines

    -95 calories/apple madeleine
    -Oven Temperature: 250°F/121°C or steamed

    • 1 large egg
    • 1/8 cup granulated sugar
    • 2 teaspoons maple syrup, grade A dark amber
    • 1/8 teaspoon vanilla extract
    • pinch of salt
    • 3 tablespoons + 1 teaspoon all-purpose flour
    • 2 teaspoons cornstarch
    • 1 teaspoon butter
    • 2 teaspoons applesauce, unsweetened
    • 2 teaspoons plain yogurt
    • 1 teaspoon finely ground lightly-roasted peanuts
    • confectioner’s sugar and cocoa powder for dusting

    If baking, preheat oven or cooker to 250°F/121°C.

    1. Thoroughly mix together the flour and cornstarch in a small bowl and set aside. The cornstarch is there to lighten the flour. To make a denser cake, add more all-purpose flour and take away an equal amount of cornstarch.  The reverse will make a lighter cake. Be careful about the extremes. Too much all-purpose flour could collapse the egg foam. Too much cornstarch and the cake will set up as a crunchy mass of egg foam.

    If available, cake flour can be substituted for the all-purpose flour and cornstarch.

    2. Put butter and applesauce in a small bowl and heat in a microwave on low until butter is melted. Mix in plain yogurt. The consistency of the applesauce and yogurt will vary by brand and type. Both should be slightly watery. If they are too thick, mix in a few drops of water to thin them out, so they do not collapse the egg foam.

    The yogurt and applesauce will hold the butter in a suspension at room temperature, but try to keep the mixture warm until needed, so that the butter stays liquid. Any chunks of butter in this mixture could collapse the egg foam.

    3. Put the egg, sugar, vanilla, maple syrup and salt in a heatproof bowl and whisk until frothy. I used a grade A, dark amber maple syrup, which is in balance with the other flavors. For a stronger maple presence, add more syrup (and cut back on the yogurt), try a stronger-tasting grade B syrup, or add a bit of maple extract.

    4. Bring a saucepan with water to a simmer and place the heatproof bowl over the saucepan. Monitor the temperature of the mixture with an instant-read thermometer. Stir the mixture until it reaches a temperature of 100°F/38°C. Heating the mixture will help it hold more air when it’s whipped.

    Whisk Marks Quickly Dissolve In Partially Whipped Egg Foam

    Whisk Marks Quickly Dissolve In Partially Whipped Egg Foam

    5. Remove the bowl from the saucepan and whip the egg foam with an electric mixer on HIGH speed until the batter turns a pale yellow and batter dripped from the beater forms a ribbon that is visible for about 2-3 seconds (about 3 or 4 minutes, depending on the speed of the mixer).

    Whisk Marks Remain Visible In Fully Whipped Egg Foam

    Whisk Marks Remain Visible In Fully Whipped Egg Foam

    6. Put the egg foam back over the simmering water and continue beating. Monitor the temperature of the batter carefully. When it reaches 110°F/43°C, remove the bowl from the saucepan and continue beating until a ribbon dripped from the beater stays visible for at least 15 seconds. It will reach this ribbon stage very quickly, within 2 or 3 minutes, once the batter is fully heated.

    7. Sift a small portion of the flour mixture over the batter and fold in with a spatula or large soup spoon.

    8. Drip a portion of the butter-applesauce mixture along the edge of the batter where it meets the bowl. Fold the butter and applesauce into the batter. Do not add the butter and applesauce mixture directly into the batter or it could collapse the egg foam.

    9. Repeat steps 7 and 8 until both mixtures are completely incorporated. If the butter-applesauce mixture is too thick to keep the batter adequately hydrated, mix a few drops of water into the butter-applesauce mixture to thin it out a little. A batter that is too dry will collapse the egg foam.

    10. Grease the apple cake molds and sprinkle grounds peanuts into each of the molds. I tried folding the peanuts into the batter, but that caused the batter to collapse. Although Tovolo silicone molds are supposed to be pumpkins, in silhouette, they resemble apples. For reference, each mold holds 3/8 cup.

    11. Carefully spoon batter into the molds. There should be enough batter to fill each mold 3/4 full.

    12. For steaming: The cakes can be wet-steamed, but I recommend dry-steaming for the best result. Wrap each mold in a foil pouch (with room for expansion) or place the molds in a tall pan (such as a springform pan) that will fit the steamer and cover the top of the pan with foil. Bring the steamer water to a rolling boil. Reduce heat to a medium boil. Place molds in steamer and steam for 12 to 15 minutes if foil-wrapped, longer if the molds are housed inside another pan. Skip to step 16.

    13. For slow baking: If baking in a large cooker, put the molds on trivets so that they don’t touch the bottom of the crock. The trivets in the top image above are made from rolled up aluminum foil. I have also tried putting the molds on a small baking sheet, elevated by a wire stand or a heatproof bowl underneath. In the second image above, the baking sheet is really the bottom of a springform pan. The wire rack holding up the baking sheet isn’t visible.

    Wire Rack Aids Stacking 2 Madeleines In A Small Cooker

    Shown above is a way to bake the cakes in a smaller 1.5-quart cooker. Two madeleines can be stacked in the small crock with the aid of a homemade wire rack. These cakes are delicate, so if they will be stacked, I recommend putting a strip of aluminum foil around the lower pan so that it doesn’t bake faster than the upper pan. Additionally, the stacked pans should be aligned in the same direction, so that they bake evenly.

    For more information about the homemade trivets and wire racks, see Low Temperature Baking: A Journey of 3 Paths ]

    14. Cover the top of the cooker with paper towels and put on lid. This step is not necessary for oven.

    15. Bake until the surface of the cakes is a light golden brown and the edges are lightly browned, about 50-60 minutes. Test the cakes by inserting a toothpick or wood skewer in the center of one. It should come out clean, excluding any surface moisture. Turn the oven or cooker off. If the cakes have any surface moisture, allow them to dry off in the oven for another 10 minutes. (For a cooker, replace the lid without the paper towels and tilt the lid to vent moisture.)

    16. Remove the madeleines and cool.

    17. Unmold and dust the top of each cake with cocoa powder or confectioner’s sugar.