What is parchment paper made of?

What is parchment paper made of

Parchment paper is an indispensable tool in the kitchen. One can only point out a handful of heating applications that parchment paper cannot be used for in ovens, toaster ovens or microwave ovens. In pre-baking, it's glossy essence helps keep the surface of countertops pristine and in post-baking, it's non-stick and moisture-sealing attributes makes food storage seemingly uncomplicated.

In this article, we're going to find out exactly what makes parchment paper this versatile in the kitchen. We'll also cover to a brief extent, other related aspects like safety, uses, recycling, compostability and durability of parchment paper.

What is parchment paper made of? Parchment paper is made from unsized paper sheet which is essentially a paper that has not been treated with chemicals to improve it's surface strength and water resistance. The porous nature of this paper enables it to readily and instantly absorb acid solution during the parchmentization process, and restructure it's fiber bonding to form parchment paper.

The Parchment Paper Process

a) Making of unsized paper
b) Bathing unsized paper in acid solution -parchmentization
c) Coating with release and moisture proof agents.
d) Packaging

a) Making of unsized paper:

Unsized paper is simply a paper that has no sizings or fillers added to it during production or after production. A size material or substance is applied to or incorporated into paper materials to change their absorption and wear characteristics. Unsized paper absorbs water and other fluids readily and instantly which makes it suitable for parchmentization.

The making of unsized paper involves extraction of fiber from different materials i.e wood, sugar cane residue, flax, cotton rags etc. chemically or mechanically and then processing these fibers into sheets of papers without any sizing or filler materials added. The more fiber a material has the better the quality of the final paper produced from it.

The Chemical and Mechanical Pulping Process:
  • In chemical pulping process, log of woods are debarked by tumbling them in large steel drums and then chipped into small pieces using a chipper. The chips are then screened for size, cleaned and temporarily stored for further processing. The barks removed cannot be used further in the paper making process, so it is burned to supply fuel instead.
  • Next, the chips are fed into a pressure cooker containing a chemical solution and boiled at high pressure to separate into fiber, lignin, and the chemical binding the substances together (cellulose). This forms a soft wet mass known as pulp.
  • The resulting mixture is then cleaned to remove the lignin and cooking chemicals, which are re-purposed for other applications along the production chain. 
  • In mechanical pulping, the debarked logs are grounded directly into pulp using a rotating stone grinding wheel. The fiber content is much higher than chemical pulping, yielding over 90% of the wood pulp as fiber.
    • Next, the naturally brown pulp is bleached into a gleaming white color or left unbleached and added with other recycled paper pulps i.e newspapers or rag papers that have been purified, de-inked and turned into pulp in a separate pulping process. This helps add more fibers especially for pulps derived from the chemical pulping, since the yield is only about 50 - 60% fiber content. Sometimes these recycled materials are used instead of wood fiber to prevent environmental degradation.
    • The bleached or unbleached pulp is then passed through a refining or beating process to improve the fiber bonding which was previously few and inflexible. Water is then added to the pulp to make a thin mixture consisting of 1 percent fiber and 99 percent water. This slurry pulp is then cleaned, screened and conveyed to the paper making machine. 
    • At the paper making machine, the slurry pulp is formed into a sheet by eliminating some of the water, and then conveyed to the pressing section where the pulp sheet is pressed through a series of rollers to drain more water and form into paper. The paper is passed over dryers to further remove water and then finally passed through metal rollers called calenders to smoothen the surface and even it's thickness. The paper is is now ready to undergo the parchmentization process.

    b) Parchmentization Process.

    This process converts the bleached or unbleached unsized paper into parchment paper.
    • In preparation for the parchmentization process, the unsized paper web is checked for any deformities before the parchmentization process begins.
    • Next, unsized paper web is rolled down into a bath containing sulfuric acid, phosphoric acid or zinc chloride, at a pre-determined speed to ensure the paper only makes contact with the acid for a specific amount of time, usually in seconds.
    • Th acid bath ties the loosely interspersed and intertwined mesh fibers in the paper anew. The spaces which originally allowed water and other fluids to pass readily are closed. This is achieved by dissolving the surface of the fibers into a gelatinous mass.
    • The paper coming out from the acid bath is then washed to remove the adhering acid and passed over drying drums to dry out and fully form. The unsized paper is now a parchment paper.
    • As the result of the parchmentization process, the original paper undergoes such modification that it no longer soften or separates when soaked or boiled in water. It becomes tough, dense, heat resistant, impervious to water, greaseproof , impermeable by air, odorless, tasteless, and chemically pure. 

    c) Extra Coating 

    Coatings are added to the raw parchment paper to add some qualities or further improve some of it's weak characteristics such as heat resistance and moisture retention. Parchment paper made form the above procedures is highly hygroscopic, which means it readily absorb moisture and cannot satisfactorily store moist foods.
    • Silicone coating is used on the surface of the parchment paper to enable it withstand temperatures of upto 450°F, which is ideal for oven use. The coating also improves on the already existing non-stick and moisture retention properties of the parchment paper.
    • The paper from the parchmentization process is simply sprayed with liquid food grade silicone and then passed over dryers to bake and dry. The final paper is now non-stick, moisture proof and heat stable at temperatures upto 450°F.
    • Alternatively, a wax coating can be made on the surface of the parchment paper or impregnated into it, to improve the moisture retention and non-stick characteristics. This make the paper ideal for wrapping and storing food articles with high moisture contents such as butter or fruits.
    • The wax coating is either imparted on the surface of the paper or impregnated into it.

    d) Packaging

    • After the parchmentization, coating and drying processes, the parchment paper is cut and molded into different shapes, sizes and packed into containers for shipping.
    Parchment paper is named after the old parchment writing paper which is made form specially prepared untanned skins of animals, due to their similar appearance. alert-information

    What are the characteristics of parchment paper?

    Culinary parchment paper has the following characteristics:
    • Heat resistance: procured from the parchmentization process and the extra silicone coating.
    • Non-stick: procured from the parchmentization process and the extra silicone or wax coating.
    • Moisture proof: mainly procured form the wax or silicone coating, although the paper after the parchmentization is moisture proof to a fair degree.
    • Odorless
    • Tasteless
    • High wet strength: procured mainly form the parchmentization process.
    • Toughness: procured mainly from the parchmentization process.
    • A good degree of pliability and flexibility.

    How strong is parchment paper?

    Chemical conversion of unsized paper fibers into a thick gelatinous mass; which dissolves and completely fills the interstice and bonds the whole fibers into a homogeneous mass, makes the resulting paper both strong in water and under heat.

    Silicone coated parchment paper can withstand oven temperatures upto 450°F. It may only begin to brittle around the exposed edges at temperatures slightly higher than that, and eventually smoke at greater temperatures. The paper can also withstand long boiling or soaking without softening or separating into it's original fibers like normal papers do.

    Wax coated parchment paper is more suited for microwaving or food storage since the wax coating on it is unstable at high temperatures.

    In addition to all these, parchment paper will readily combust when it comes in contact with heating elements like those in toaster ovens or open flame. It is heat resistant but readily combustible.

    Where can parchment paper be used?

    In conventional ovens: The safe "heating limit" for parchment paper in the oven is usually 450°F. Above that, it is susceptible to disintegration. Most recipes call for temperatures below 450°F so it should be fine for everyday use.

    In microwave ovens: Parchment paper is safe to use in microwave ovens. Unlike in conventional ovens where dry heat is used to cook the surface of food, in microwave ovens, food molecules are directly targeted by microwave radiation for cooking. Parchment paper is largely transparent to this microwave radiation and so it doesn't get heated by it.

    In toaster ovens: Just like in conventional ovens, food is cooked using dry heat from the outside to the inside in a toaster oven. So the air inside get very hot and so parchment paper are susceptible to brittiling or smoking at temperatures above 450°F. Another thing with toaster ovens is that care must be taken to ensure no part of the parchment paper is left hanging, to prevent possible contact with the heating elements or walls of the oven.

    In air fryers: Perforated parchment paper is safe to use in an air fryer to make cleanup easier. The perforations ensure proper circulation of hot air around the cavity which will result in an evenly cooked food. A safety tip is to always make sure that the perforated parchment paper is a few centimeter below the heating coil and is pressed down properly by the weight of the food, to avoid fire. Also, make sure to preheat the air fryer first before putting in the parchment paper otherwise it could fly off and catch fire.

    Not recommend for broiling: Parchment paper is not recommended to be exposed directly under broilers for the same reason that it's not supposed to be left hanging in toaster ovens - it may catch fire.

    How safe is parchment paper?

    Parchment paper is manufactured bleached or unbleached.

    Chlorine bleached parchment paper is not entirely safe for cooking and food storage. It may leach harmful dioxin substances into food during these activities, although the amounts deposited are infinitesimally small and do not appear to present any health risk to individuals. Then again, the very persistent nature of dioxins along with their highly toxic potential means that they could still buildup to toxic levels over lifetime and eventually present their health risks.

    For this reasons and more, unbleached parchment paper and those bleached with substances other than chlorine are mostly preferred for everyday household use.

    Read more on dioxins: Is parchment paper safe?

    As for the silicone or wax coating on the surface of the parchment paper, they are all made from food grade materials which means they are safe and non-toxic even when they come in contact with food or are ingested.

    Is parchment paper biodegradable?

    Silicone parchment paper is not biodegradable due to the silicone coating on it. Silicone cannot be broken down by living organisms and reincorporated into nature. So it is not biodegradable.
    However, unlike plastic which can give off toxins when broken down, high grade silicone, the one used for coating kitchen wares, is chemically inert. This means that silicone parchment paper is friendly to the environment and does not contribute to environment degradation.

    Is parchment paper compostable?

    It is not entirely clear (based on research) about the compostability of the silicone coating on parchment paper. However, uncoated parchment paper can be added to the compost pile.

    What are other papers similar to parchment paper?

    • Wax paper: Paper coated with food grade wax.
    • Aluminum foil: Aluminum metal rolled into a thin metal leave.
    • Freezer paper: Regular paper coated with plastic on one or both sides.
    • Silicone baking mat: Baking mat coated with food grade silicone.

    What are the uses of parchment paper? 

    The non-stick property of parchment paper is useful to prevent baked goods from sticking to the surface of the pan. It eliminates the need for the traditional method of greasing the surface of the pan with cooking spray or butter, there by cutting the extra amount of fats and oils attached with it. The non-stick property is also useful as an interleave between sticky baked goods to ensure easy release. It also a good surface for working butter, dough and sifting ingredients.

    As a heat sealant, parchment paper is useful for steam cooking certain kind of food like chicken breast, salmon or sea foods. The articles are enclosed in a packet form of parchment paper and steamed in their own juice for flavor, tenderness, and moistness. 

    As a moisture and vapor proof surface, waxed parchment paper is useful for storing moisture rich foods like butter, cheese and fruits. It will prevent moisture escape and preserve the freshness and taste of the food.

    Need more uses of parchment paper? Read under the sub heading "Uses of parchment paper": Is parchment paper the same as wax paper?

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