AY Honors/Food - Drying/Answer Key/es

1

Hacer una lista de por lo menos tres diferentes formas de deshidratar alimentos.

Secar al sol

La comida puede ser secada al sol, pero solo si las temperaturas son cerca de 100° F (38° C) y la humedad es baja. La fruta debe ser cubierta con una gasa (o algo similar) para protegerla de los insectos. Si se seca sobre una mesa, las patas de la mesa deben establecerse en latas de agua para evitar que los insectos suban por las piernas y lleguen a la fruta. La fruta se tardará varios días en secarse, y la humedad y otras condiciones climáticas deben ser monitoreadas. Si la temperatura baja considerablemente durante la noche, el rocío puede formar y la fruta lo absorberá rápidamente. Debido a esto, puede ser necesario entrar las frutas por la noche.

Secar al horno

Esta es la manera más rápida para secar los alimentos, pero sólo pequeñas cantidades a la vez se pueden secar de esta manera. El horno se precalienta hasta aproximadamente 140° F (60° C) y la comida se coloca en bandejas en el horno. La puerta debe estar abierta alrededor de dos pulgadas (5 cm) para un horno de gas, o alrededor de 4 pulgadas (10 cm) para un horno eléctrico. Un termómetro se coloca en el centro de la bandeja para asegurarse de que la temperatura se mantiene cerca de 140° F (60° C). Un ventilador debe colocarse cerca de la puerta del horno abierta para que el aire dentro del horno pueda circular y permitir que la humedad se escape.

Las bandejas de comida deben ser rotadas cada 30 minutos para que el calor dentro del horno no se distribuya de manera uniforme. Gire las bandejas de adelante hacia atrás, de arriba a abajo y de izquierda a derecha.

Secador de Alimentos

Secadores de comida se pueden comprar construir. Pueden secar más alimentos que un horno, pero se necesita un poco más de tiempo. También utilizan menos electricidad que un horno eléctrico. Un secador de alimentos es una caja cerrada con una fuente de calor, un ventilador y un conjunto de bandejas donde se coloca los alimentos. La mayoría de las secadoras de alimentos hechas en casa utilizan una bombilla de 100 vatios como la fuente de calor. Se tarda de 4 a 6 horas para secar una tanda de alimentos en un secador de comida y, como los hornos, operan a aproximadamente 140° F (60° C).

A spray dryer takes a liquid stream and separates the solute or suspension as a solid and the solvent into a vapor. The solid is usually collected in a drum or cyclone. The liquid input stream is sprayed through a nozzle into a hot vapor stream and vaporised. Solids form as moisture quickly leaves the droplets. A nozzle is usually used to make the droplets as small as possible, maximising heat transfer and the rate of water vaporisation. Droplet sizes can range from 20 to 180 μm depending on the nozzle.

Spray dryers can dry a product very quickly compared to other methods of drying. They also turn a solution, or slurry into a dried powder in a single step, which can be advantageous for profit maximization and process simplification. Powdered milk, tea and coffee are common product that are spray dried.

Drum Drying

Drum drying is a method used for drying out liquids; for example, milk is applied as a thin film to the surface of a heated drum, and the dried milk solids are then scraped off with a knife. Powdered milk made by drum drying tends to have a cooked flavor, due to caramelization caused by greater heat exposure.

Compared to spray drying, drum drying is a more intense heat treatment which results in more denatured proteins. The powder is less soluble as a result. The temperature uniformity of the heated roller/drum is poor so spray drying results in better quality milk powder.

Other products where drum drying may be used: starches, breakfast cereals, baby food, and instant mashed potatoes.

2

¿Por qué y cómo se le añade azufre a las frutas deshidratadas?

Commercially prepared dried fruit may contain sulfur dioxide which can trigger asthma in sensitive individuals, though dried fruit without sulfur dioxide is also available, particularly in health stores. The sulphur is added to "fix" the colour of the product. "Organic" dried fruit is produced without sulphur which results in dark fruit and the flavor is much more characteristic of the fresh fruit. The color of some fruits can also be "fixed" to some extent, with minimal impact on flavor, by treating the freshly cut fruit with a preparation rich in Vitamin C (e.g., a mixture of water and lemon juice) for a few minutes prior to drying.

Sulphuring fruit is accomplished by burning a block of sulphur in an enclosed box (such as a dehydrator) with the fruit inside. The burning sulphur gives off sulphur dioxide which fixes the color of the fruit. This should only be done outside.

3

¿Cómo se almacenan y se protegen las frutas deshidratadas de los insectos?

As soon as it cools, dried fruit should be packed into insect-proof containers, such as glass jars or metal cans with tight-fitting lids. Do not let sulphured fruit touch metal, as this will cause the fruit to become discolored. You can pack fruit into plastic bags and then place that in a metal container. Plastic bags are not 100% insect (or rodent) proof, so make sure you store the fruit in a place where they cannot get to it. A cool, dry place is best.

4

¿Cómo se reconstituyen los alimentos deshidratados?

Just add water. You can also simmer them in boiling water for 15 minutes.

5

¿Por qué es importante la selección de frutas para ser utilizadas en los dulces de frutas deshidratadas?

The fruit must be ripe, or slightly overripe. Be sure to use good quality fruit, as it will make good quality fruit leather. Select fruit that is fresh, and fully sound - basically, the same things you look for when selecting fruit for the table. Cut out any bad parts of the fruit. The saying, "one bad apple spoils the whole lot" applies to fruit leather, as a bad piece of fruit can impart a bad flavor to any of the fruit it comes into contact with. In making fruit leather, the fruit is pureed before drying, so the bad fruit will come into contact with all the fruit.

6

¿Cómo se almacenan las nueces secas?

Dried nuts must be stored in a cool, dry place in air-tight containers to prevent reabsorption of moisture.

7

Secar lo siguiente y proporcionar muestras para probarlas:

7a

Pan (hacer pan rallado y utilizarlo en una receta para muestra)

Bread can be dried without the use of special equipment by placing several slices in a large bowl and covering it with a towel. The bowl should be kept indoors. After several days, the bread will be dry (also known as "stale") and it can then be crumbled. You can also dry bread quickly in a food dryer. Just cut it up into bite sized chunks.

The usual use for bread crumbs is to make stuffing. You may use any stuffing recipe you like (as long as it uses bread crumbs), or you can use this one:

Adventist Youth Honors Answer Book/Stuffing Recipe

You can also use your dried bread as homemade croutons to toss on a salad.

7b

Frutas

Wash the fruit and puree it in a food processor. Line a shallow pan with wax paper, being sure to bring the edges up so that the pureed fruit cannot run under it. Pour the fruit puree into the pan until it is about a quarter inch deep (0.6 cm). Place it in the food dryer set to 140°F (60°C). Check it after four hours (but it may take much longer). Remove the fruit when it is tacky to the touch. Remove it and the wax paper from the pan and slice into thin strips, leaving the wax paper attached. Roll the strips (and wax paper) into a spiral and place in a sealable plastic bag. Store in a cool dry place. Fruit leather can be stored for up to six months.

7c

Vegetales

You can make vegetable leather from just about any type of vegetable so long as it is pureed first. A shortcut is to use baby food as the starting point, and then proceed as with fruit leather. Here are two other recipes (in case your Pathfinders rebel at the thought of eating baby food).

Pumpkin Leather

• 2 cups of canned pumpkin, or 2 cups of fresh pumpkin, cooked and pureed.
• 1/2 cup honey
• 1/2 teaspoon cinnamon
• 1/4 teaspoon nutmeg (powdered)
• 1/4 teaspoon cloves (powdered)

Combine ingredients and dry at 140°F (60°C) (same as for fruit leather).

Tomato Leather

Core and slice ripe tomatoes into quarters. Boil for 15 minutes. Remove from water, force through a colander or a sieve. Add salt (if desired for flavoring), and simmer until thick. Spread on a plastic or wax paper lined tray and dry at 140°F (60°C) (same as for fruit leather).

7d

Rebanadas de frutas

Most fruits need to be pretreated before they are dried. Apples should be cored, peeled, and sliced. Fruits with pits (such as peaches, nectarines, and cherries) should be split in half and pitted.

Thin slices of fruit dry quicker than thick slices, so it is important to slice fruit into uniform thicknesses so that it dries evenly.

Fruit with thick, waxy skins (such as blueberries and cherries) must be cracked before it is dried. Cracking the skin allows the moisture to escape. To crack the fruit, drop it in boiling water for 30-60 seconds, and then quickly move it to very cold water.

Some fruits, such as apples, pears, and apricots become discolored quickly after they are peeled and sliced. To prevent them from turning brown, mix two teaspoons of ascorbic acid in one cup of water, and dip the fruit in this solution as you work with it. One cup of this solution should be enough to treat five quarts of fruit. Ascorbic acid (more commonly known as Vitamin C) is available in most drug stores. You can also crush a 500mg tablet of Vitamin C and mix that with a quart (one liter) of water. Soak the fruit in that solution for two to three minutes.

Once the fruit has been prepared, arrange it in a single layer on a drying tray with the cut side up (if cut in half). Finally, place the trays in a food dryer, and wait. The amount of time varies depending on the fruit, how thick the slices are, et cetera. It should take between four and ten hours to dry.

7e

Vegetales rebanados (como las zanahorias) o los trozos (como los guisantes)

Select ripe, high quality vegetables. Cut out any bad spots, discard overripe pieces, and slice into thin, uniform pieces (unless you are starting with small vegetables such as peas).

Nearly all vegetables need to be blanched before they are dried. Blanching stops enzymes from destroying the vegetables. Drying by itself does not stop the enzyme action. To blanch vegetables, drop them in boiling water for a minute or two. Then cool them in ice water for the same amount of time that they were blanched. Blanching does remove some nutrients from the vegetables, so be sure to blanch them for only the minimum specified time (see table).

Arrange the vegetables on a drying tray in a single layer. Place the trays in the dryer at 140°F (60°C) with a minimum of one inch between trays. Drying will take between four and twelve hours. Turn the vegetable pieces every thirty minutes and rearrange them on the tray so that they are dried evenly (different areas on the trays will dry at different rates). The pieces are dry when they are hard and brittle. You can test them by striking a piece with a hammer. If it shatters, the vegetable is dry.

Vegetable	Blanching Time (minutes)	Drying Time (hours)
Asparagus	3.5 - 4.5	1 - 3
Green Beans	3 - 4	2.5 - 4
Carrots	3.5	2.5 - 4
Corn	5 - 8	4
Onions	do not blanch	1 - 3
Peas	3	3
Potatoes	6 - 8	2 - 4
Summer Squash	1.5 - 2	2.5 - 3
Tomatoes (3/4" thick)	1	3.5 - 4

7f

Mezcla vegetariana

• 1 lb firm tofu
• 1/2 cup Bragg Liquid Aminos
• 3-4 tablespoons liquid smoke
• 1 teaspoon garlic powder
• 1 teaspoon salt
• 1 teaspoon pepper
• 1 teaspoon honey
• 1 teaspoon onion powder
• 1/8 cup water

1. Drain and slice the tofu into quarter-inch (5mm) thick, long, narrow slices
2. Mix all the ingredients, adding the tofu slice last in shallow baking dish. Cover and refrigerate overnight.
3. Dry at 140°F (60°C) 4-6 hours, turning hourly.

Easy Vegetarian Jerky

• Stripples (Worthington)

1. Spread Stripples out in a single layer in food dehydrator or oven (set on lowest temperature setting).
2. Turn stripples once or twice as needed for even drying, throughout drying time.

7g

Perejil o alguna otra hierba

Fresh parsley, mint, oregano, basil, marjoram, and rosemary can be dried without any special equipment. Simply bundle the fresh herbs and hang them in a dry corner of the kitchen out of direct sunlight for a couple of weeks. You can also dry them by spreading them out on a dish towel.

8

Reconstituir un vegetal y cocinar como muestra.

Vegetables can be reconstituted by soaking them in water for two or three hours. They should return to their full size. Cook any way you like.

References

• http://extension.usu.edu/files/foodpubs/fn330.pdf Utah State Extension
• http://www.extension.uiuc.edu/~vista/html_pubs/DRYING/dryfood.html University of Illinois at Urbana-Champaign.
• http://www.thefarm.org/charities/i4at/surv/dryguide.htm
• http://homeorchard.ucdavis.edu/8005.pdf Storing nuts
• http://nchfp.uga.edu/how/dry/fruit_leathers.html Good ideas to make interesting fruit leathers