Field of the invention

The present invention relates to pulp compositions suitable for moulding and moulded pulp article(s) and their preparation. In particular, the invention relates to biodegradable and/or compostable pulp compositions, moulded pulp article(s) and their preparation thereof

Background of the invention

Disposable products made from polymer-based plastic, such as polystyrene and polyethylene, are generally not considered to be environmentally friendly. Such disposable plastic products may be used for food packaging and containers. It is estimated that a single plastic product may take up to 1000 years to decay completely. The persistence of plastic can result in ecosystem damage. In order to reduce the plastic presence, plastic may be incinerated together with the bulk garbage prior to dumping in landfills. However, the incineration of plastic has its fair share of disadvantages, the biggest being toxic fumes released into the environment, thus resulting in air pollution.

In addition, there are increasing concerns on the effects of polystyrene food containers. Hot food or beverages may cause styrene chemicals to leach into food or drink. This is a health concern as very high doses of styrene act as a neurotoxin, may be carcinogenic and affect fertility.

Biodegradable disposable products are available. The European Standard EN13432 "Requirements for packaging recoverable through composting and biodegradation - Test scheme and evaluation criteria for the final acceptance of packaging", defines a set of characteristics that a material must have, in order to be defined as "compostable". Not all disposable products presently available meet this standard. It is therefore desirable to develop environmentally friendly disposable products capable of rapid biodegradation.

Summary of the invention

The present invention relates to pulp compositions suitable for moulding and moulded pulp article(s) and their preparation. In particular, the pulp compositions and/or moulded pulp articles are biodegradable and/or compostable.

According to a first aspect, the present invention provides a process for preparing a biodegradable and/or compostable pulp composition comprising the steps of:

(i) providing a pulp composition;

(ii) adding at least one protease to the pulp composition.

The present invention also provides a biodegradable and/or compostable pulp composition comprising substantially of fibres from: a plant or part thereof, wood or recycled paper or any combination thereof and at least one exogeneous protease.

The biodegradable and/or compostable pulp composition according to the invention is suitable for moulding at least one moulded pulp article. Accordingly, the biodegradable and/or compostable pulp composition is mouldable. The moulded pulp article is also biodegradable and/or compostable.

According to another aspect, the invention also provides a biodegradable and/or compostable moulded pulp article comprising at least one exogenous protease impregnated throughout the pulp article. Brief description of the figures

Figure 1 shows examples of moulded pulp articles according to the invention; (A) three-section plate; (B) plain plate; (C) five-section tray; (D) bowl; (E) cups; (F) cutlery; (G) clam-shell lunch box; (H) meat tray; (I) egg tray (or egg carton) and (J) wine tray.

Figure 2 shows the temperature change during the disintegration test.

Figure 3 shows the oxygen concentration in the exhaust air during the disintegration test.

Figure 4 shows the C0 ₂ production rate during the disintegration test. Figure 5 shows a visual presentation of the evolution of the disintegration in the slide frames during 12 weeks of composting.

Figure 6 shows a visual comparison of the < 0 mm fraction of control and test compost obtained after 12 weeks of composting.

Definitions "Agricultural waste" refers to any matter from premises used for agriculture or horticulture, which is discarded, to be discarded or is required to discarded. It is waste specifically generated by agricultural activities.

"Exogenous" as used herein, describes a compound from a source outside or external to a composition. In particular, the exogenous compound has been added or introduced to the composition. For example, in the context of the present invention, a protease was added to a pulp composition. The protease is exogenous to the pulp composition even though both may be from the same plant. For example, the pulp composition may be from the stem while the protease may be from the fruit of the same plant. In a further example, the protease is also exogenous if obtained or purified from a separate batch of stems to the pulp composition.

"Bagasse" refers to the residue left behind after a plant or part thereof has been subjected to squeezing, crushing, grinding pounding or other mechanical or chemical processing. For example, bagasse refers to the residue left behind after a plant or part thereof has been processed to extract a product (for example: juice). Bagasse typically comprises fibre, pith (the spongy tissue of a plant), non-soluble solids and water. Bagasse may be obtained from any plant or part thereof including but not limited to sugarcane, grasses, cereal plants, bamboo, palm, corn, yam or coconut. Sugarcane bagasse is the fibrous product remaining after sugarcane stalks have been crushed to extract juice and is a by-product of the sugar industry.

"Biodegradable" describes any material capable of being substantially degraded, decomposed or broken down by natural or biological processes. "Composting" or "compostable" refers to the biodegradation or decomposition of organic matter and is carried out by various microorganisms, including bacteria, fungi and the like. The product of composting is compost which comprises a mixture of decaying organic matter. Compost may be used as a fertiliser. "Impregnate" or "impregnated" as used herein means to cause a compound to be dispersed completely. Impregnated throughout means that the compound may be found in every part of an article, that is both within and on the surface of the article. For example, the impregnated compound may be embedded throughout the structure of the article. A "moulded pulp" (also known as "moulded fibre") article refers to an article moulded from pulp. Moulded pulp articles may be moulded into almost any shape and size from pulp. Examples of moulded pulp articles include but are not limited to cutlery, containers, for example food containers (bowls, plates, cups, clam-shell containers), trays, egg cartons and other packaging material.

"Non-wood" fibres refer to fibres from any non-wood plant or non-wood part of a plant. For example, non-wood fibres may be from the stem of non-wood plants, which are plants which do not have woody stems. Woody plants may also have non-wood plant parts and non-wood fibres encompass fibres from these non- wood plant parts.

"Non-wood" plant refers to a plant which does not have woody stems.

"Non-wood" plant part refers to a plant part which is not woody. For example, the stem of a non-wood plant is a non-wood plant part. Woody plants may also have non-wood plant parts, for example stalks, leaves.

"Pulp" refers to a composition comprising primarily of fibres derived from a plant or part thereof, wood or recycled paper, suitable for processing into paper or moulded pulp articles. Pulp also includes the substantially dry material prepared by chemically or separating fibres from wood, plant material or waste paper.

"Straw" refers to the dry stems or stalks of plants. Detailed description of the invention

The biodegradable and/or compostable pulp composition according to the invention comprises at least one exogenous protease. The biodegradable and/or compostable pulp composition is generally prepared by adding at least one exogenous protease to a first pulp composition. The first pulp composition may be prepared from a plant or part thereof, wood, recycled paper or any combination thereof. Conventional pulping methods, including but not limited to mechanical, chemical, thermo-mechanical pulping methods or a combination thereof may be used to prepare the first pulp composition. Accordingly, the first pulp composition comprises substantially of fibres from a plant or part thereof, wood or recycled paper or any combination thereof.

For example, the first pulp composition may be from a non-wood plant. Examples of such plants include but are not limited to sugarcane, grasses, cereal plants, bamboo, palm, corn, yam, coconut and kenaf. Non-wood plant parts may also be used for preparing the first pulp composition. Either the entire plant or parts of the plant including but not limited to stems, stalks, leaves, roots and husks may be used for preparing the first pulp composition (pulping). The first pulp composition may also be prepared from any combination of plants and/or any combination of plant parts. In particular, the plant or plant part may be part of agricultural waste. The first pulp composition may be prepared from non-wood fibres of these plants and/or combination of plants. In particular, the non-wood fibres with diameter from 2.5 to 10 μηι may be selected for preparing the first pulp composition. Secondary characteristics in addition to fibre diameter may also be considered for the fibres. An example comprises selecting for fibres with a moisture content of < 12% of its dry weight.

Examples of cereal plants include sorghum, rice, wheat and the like. The stems or stalks of these plants may be used directly for preparing the pulp composition (pulping). Alternatively, the stems or stalks may be dried to form straw and the straw is then used for preparing the first pulp composition (pulping). Bagasse may also be used for preparing the first pulp composition (pulping). In particular, the sugarcane bagasse may be used for preparing the first pulp composition (pulping). Any combination of stem, stalk, bagasse and/or straw may also be used for preparing the first pulp composition (pulping). Pulp made from recycled paper may also be used. Such recycled pulp and also pulp from bagasse and other agricultural waste is considered more environmentally friendly compared to pulp from freshly chopped plants or trees. After pulping, the protease is added to the first pulp composition and mixed. The protease may be selected from the group consisting of: serine proteases, threonine proteases, cysteine proteases, aspartate proteases, metalloproteases and glutamic acid proteases. A combination of proteases may also be used. In particular, the enzyme papain may be used. Papain is a cysteine protease from Carica papaya (papaya) or Vasconcellea cundinamarcensis (mountain papaya).

Accordingly, the biodegradable and/or compostable pulp composition comprises substantially of fibres from a plant or part thereof, wood or recycled paper and at least one exogeneous protease. The fibres may be from a non- wood plant or a non-wood plant part or any combination thereof. For example, the fibres may be from sugarcane, grasses, cereal plants, bamboo, palm, corn, yam, coconut and kenaf or plant part thereof or any combination thereof. In particular, the biodegradable and/or compostable pulp composition comprises substantially of fibres from sugarcane bagasse and at least one exogenous protease. Accordingly, the biodegradable and/or compostable pulp composition may be produced by the process described herein.

After adding and mixing the protease into the first pulp composition, the pulp composition is then moulded into at least one moulded pulp article. The biodegradable and/or compostable moulded pulp article of the invention comprises at least one exogenous protease impregnated throughout the moulded pulp article. The impregnated protease retains biological activity and facilitates the biodegradation and composting of the moulded pulp article. After use, the moulded pulp article may be composted. During composting, the protease assists in breaking down the moulded pulp article and thus enhances the rate of decomposition. The moulded pulp article(s) according to the invention may be composted within 45 to 180 days. The biodegradable and/or compostable pulp composition according to the invention may also be composted. The moulded pulp article(s) were readily biodegraded and/or composted and conform to the European Standard EN 13432 "Requirements for packaging recoverable through composting and biodegradation - Test scheme and evaluation criteria for the final acceptance of packaging". In general, the moulded pulp article(s) according to the invention may be biodegraded and/or composted within 45 to 180 days. It was further observed the compost obtained from biodegradation and/or composting of the moulded pulp article(s) with impregnated protease was observed to be finer than compost from biodegradation and/or composting of moulded pulp article(s) without added protease. This is possibly because the protease contributes to a more thorough biodegradation and/or composting process.

According to a further aspect, the invention provides a compost obtained from composting the biodegradable and/or compostable pulp composition and/or the moulded pulp article. The compost may be used to improve the structure and/or increase the moisture and water retention of soil, especially in sandy soils and thus also protects against draught and/or provide nutrients to soil. Compost also balances the pH and carbon, nitrogen, phosphorous and potassium (CNPK) of soil. The compost may also cool the surface of soil, helps break up heavy clay soils, restores minerals and micro-nutrients to depleted soils. The compost also helps the formation of aggregates in soil and this increases soil permeability and decreases the need for irrigation and fertilization. Accordingly, the compost may be used as a fertiliser.

Accordingly, the biodegradable and/or compostable pulp composition and/or moulded pulp article(s) are thus environmentally friendly. In particular, the biodegradable and/or moulded pulp article is suitable as a disposable product. The disposable moulded pulp article(s) may be used for packaging, for example, packaging for food and/or drinks. The moulded pulp article(s) may also be used for serving food, soups and/or drinks. Examples of moulded pulp articles may be trays, plates, bowls, cups, cutlery, lunch boxes and the like, as illustrated in Figure 1. Trays include trays for food and/or drink packaging, like egg trays (egg carton), wine trays, meat trays and meal trays. Examples of moulded pulp articles for serving include plates (plain or sectioned plates), cups. In addition, lunch boxes, like the claim shell lunch boxes may be used for packaging and/or serving, for example individual portions of meals. Examples of cutlery include forks, spoons, knives and chopsticks.

The biodegradable and/or compostable pulp composition ands/or moulded pulp article(s) may also be used as animal feed. The biodegradable and/or compostable pulp composition and/or moulded pulp article(s) may be fed directly to animals. Alternatively, the biodegradable and/or compostable pulp composition and/or moulded pulp article(s) may be mixed with at least one other conventional animal feed before feeding to animals. Accordingly, the biodegradable and/or compostable pulp composition and/or moulded pulp article(s) may be a source of fibre for animals. Having now generally described the invention, the same will be more readily understood through reference to the following examples which are provided by way of illustration, and are not intended to be limiting of the present invention.

EXAMPLE 1 Preparation of pulp composition

Sugarcane bagasse may be considered a waste product from for example, sugar manufacturing. Fibres from sugarcane bagasse having a diameter from 2.5 to 10 μηι were selected for pulping. Optionally, after diameter selection, fibres with a moisture content of a moisture content < 2% of its dry weight may be further selected for pulping. The fibres were cleaned or washed to remove undesirable particles, such as dirt, sand and the like before pulping. The cleaned fibres were then transferred to a pulper tank. Typically, the pulper tank comprises a pulping means. The pulping means may comprise a pulp-rig or rotating blades. The first pulping process occurs at a speed of 120 rpm for 32 to 37 minutes. This was followed by a second round of pulping at a rotation speed of 42 rpm for 1.5 to 2.5 minutes. The two rounds of pulping produced a pulp composition in the form of a slurry comprising a thick suspension of "fibrous" solids in a liquid. This is an example of a first pulp composition to which the protease may be added. Other pulp compositions may also be used as the first pulp composition to which the protease is added.

Example 2 Preparation of enzyme

Papain may be obtained from the latex of the papaya fruit (Carica papaya) with any conventional method, such as exemplified below. Three or four incisions were made in the fruits with a sharp instrument to a depth of 2 to 3 mm. The latex that exudes from the incisons coagulates rapidly and is collected into a glass container. This latex may be used immediately for extraction of papain or stored at -8 °C under a nitrogen atmosphere till the extraction of papain is required. For extracting the papain, ethylenediamine-tetraacetic acid (EDTA), pH 7.0, was added to the latex to a final concentration of 1 mM and the suspension was kept under nitrogen for 1 hr at room temperature with constant shaking. The suspension was then centrifuged at 12,000 xg for 30 minutes at the ambient temperature. The supernatant was transferred to a first vessel connected to a second vessel with 30 ml of distilled water. The first vessel was chilled in an ice bath for 72 hours to precipitate the papain. The papain precipitate was pelleted by centrifugation at 12,000 xg for 20 minutes at 0 °C. The pellet comprising papain from this centrifugation was washed three times with an appropriate amount of 1 mM EDTA, ph 7.0 at 4 °C. Centrifugation was performed again at 12,000 xg for 20 minutes to pellet the washed papain. This pellet was dissolved in an appropriate amount of 1 mM EDTA, pH 7.0. This papain solution may be stored at 4 °C till required. The papain was separated from the EDTA through dialysis and the final volume was adjusted to a suitable volume using distilled water, a solution or a buffer before adding to the pulp composition in Example 3.

Example 3 Addition of enzyme

After pulping, papain enzyme may be added into the pulp composition in batches. A first batch of 30.5 ml of papain from Example 2 was added into ~ 50,000 ml of pulp composition in a tank. The pulp composition was first stirred at 120 rpm for 32 to 37 minutes, followed by a further stirring at 42 rpm for 1.5 to 2.5 minutes, using the pulp rig. Next, a second batch of 11 ml of papain enzyme from Example 2 was again added into the pulp composition, with stirring at 55 rpm for 7 minutes. The pulp composition comprising papain may then be moulded into at least one moulded pulp article. The papain enzyme may be replaced by any other protease or combination of protease. Different protease amounts may be added in the two batches.

Example 4: Moulding The pulp composition from Example 3 may then be used for moulding into moulded pulp articles. The moulding process exemplified in this example comprised three steps. The pulp composition was first transferred to a mould. The mould typically comprises two parts with the pulp composition filling the space between the two parts. The two parts of the mould were then pressed together, followed by baking the mould and pulp composition at 170 to 240 °C for 2 to 15 seconds. This step is termed "pre-cooking". After the pre-cooking step, the mould and pulp composition was baked at 170 to 240 °C for a further 5 to 15 minutes. The second step cures the pulp composition, thus forming the moulded pulp article. By building moulds of different specifications, different moulded pulp articles may be produced according to specification.

In particular, it was surprisingly found that for the pulp composition comprising papain or other protease, the moulding process did not inactivate the protease completely. The papain or other protease retains sufficient activity to facilitate the biodegradation and/or composting of the moulded pulp article(s).

Example 5 Disintegration test

The moulded pulp articles of the present invention were tested and were found to be compliant with The European Standard EN13432 "Requirements for packaging recoverable through composting and biodegradation - Test scheme and evaluation criteria for the final acceptance of packaging". The disintegration of three samples of the moulded pulp article with thickness of 1.11 mm and grammage 476 g/m ² was tested. Figure 2 shows the temperature change during the disintegration test. The temperature remained above or around 40°C during the entire test period for all test series. Figure 3 shows the oxygen concentration in the exhaust air during the disintegration test. The oxygen concentration remained always above 10%, which ensures optimal aeration conditions. The C0 ₂ production rate during disintegration is shown in Figure 4. Figure 5 shows a visual presentation of the evolution of the disintegration in the slide frames during 2 weeks of composting. After 8 weeks of composting only a small border of test material remained present in the slide frames. The disintegration proceeded and at the end of the test, the slide frames were completely empty. After 8 weeks of composting the test item pieces seemed completely disappeared. This was confirmed at the end of the test. At the end of the composting test (after 12 weeks), the whole content of the test bins was used for sieving, sorting, further isolation and analyses. Not a single piece of test item was retrieved after carefully selecting the different compost fractions (> 10 mm, 5-10 mm and 2-5 mm). Therefore, it can be concluded that 100% complete disintegration was obtained after 12 weeks of composting.

Figure 6 shows a visual comparison of the < 10 mm fraction of control and test compost obtained after 12 weeks of composting. No visual contamination was observed.