Technical Field of the Invention

The invention is related to the production of a cellulose-based active packaging using paper, a biodegradable, sustainable, recyclable, renewable, and cheap packaging material. There are areas of use of the invention as active packaging for the food industry and the packaging industry.

State of the Art of the Invention (Prior Art)

Microbial growth increases and food degradation accelerates as the fruits are crushed as a result of some extrinsic factors (such as impacts that may occur during or after the collection of fruits). The occurrence of foodbome microbial degradation reveals the search for innovative solutions that prevent microbial growth in foods by preserving quality, freshness, and safety. Active packaging is changing the environment in the packaging in order to reduce the rate of degradation reactions and extend the shelf-life of the food or bringing new properties into the packaging material used to protect the product from extrinsic factors with absorbent-retaining or releasing-emitting systems.

The prior art tries to solve the problem of food degradation by wrapping with untreated paper or coating fresh fruits directly with substances such as wax. Packaging materials used in the preservation of fruits and vegetables do not fully fulfill the preservation feature and are only used as a barrier that separates food from the environment since they do not have any improved anti-degradation properties. The wax coating method, which is one of the methods of preserving foods, is a process that is not desired by consumers and is not preferred as much as possible. In addition, both said untreated paper packaging material and substances such as wax cannot prevent any microbial growth since they do not have antimicrobial properties.

Sericin is a cheap glycoprotein obtained as a by-product in the silk industry. Variable amino acid composition and various functional groups have attractive bioactive properties that are particularly interesting for biomedical applications. Sericin is useful in cell culture and tissue engineering thanks to its antioxidant properties, moisturizing ability, and mitogenic effect in mammalian cells. The silk sericin (SS) is one of the two main proteins that make up the silkworm cocoon, and the second of which is silk fibroin. About 50,000 tons of the 1 million tons of fresh cocoons produced annually worldwide consist of SS discharged in wastewater. It has been stated in recent studies that sericin may have the potential to be used in the field of medicine, cosmetics, and biotechnology with the evidence of its important biological activities (Lamboni et al., 2015). Sericin, which contains both proteins and anti-browning properties, is a suitable material for the production of edible films and can be used for quality improvement of minimally processed fruits and vegetables and for other applications in the food industry (Thongsook and Tiyaboonchai, 2011). Fulvic acids contain many reactive functional groups, including phenols, hydroxyls, carboxyls, and quinones. The presence of these reactive groups indicates that fulvic acid can produce many beneficial effects, including its ability to form a chelate with metals, antioxidant activity, stress management, antiinflammatory activities, and antimicrobial properties (Gao, 2007).

Sericin can be utilized as an antioxidant in the field of drugs, cosmetics, foods, and food additives. This protein is also used as a coating material for natural and artificial fibers, which can prevent abrasive skin injuries, rash, and antibacterial development for products such as diapers, diaper liners, and dressings (Sarovart et al., 2003). Many studies have shown that the use of fulvic acid in agriculture has effects such as accelerating seed germination and improving rootstalk growth, promoting oxygen transport, accelerating respiration, promoting plants’ effective use of nutrients, and balancing soil salinity (Nardi et al., 2002; Zancani et al., 2009; Zancani et al., 2011; Anjum et al., 2011; Visser, 1988). Recent studies state that fulvic acid can form a film in the mucus epithelium of the gastrointestinal tract and protect against infections and toxins, thus improving the use of nutrients in animal feed (Islam et al., 2005; Trekova et al., 2005). In addition, fulvic acid has antimicrobial and anti-inflammatory properties (Van Rensburg et al., 2001). The packaging material produced with fulvic acid has not been found in the literature; however, there are examples of films produced using sericin and different chemicals (Purwar et al., 2015; Wang et al., 2010; Purwar et al., 2019).

Patent document US5491008A refers to the permanent treatment with a mixture of fulvic acid and humic acid, or an aqueous suspension containing salts thereof, in the wet technological phase (stage) of paper production. This application has been carried out in the material or on the surface of the packaging material during the process. The electrospray system is not utilized during this process. In addition, the wet technology used is not environmentally friendly and also the presence of an aqueous environment and the moisture in the coating material increases the risk of contamination. In addition, the cost of the method used is fairly high compared to electrospray considering the efficiency-cost analysis.

Sulfonated macromolecules were produced and information was provided on areas of use such as medical devices, protective clothing and fabric, laboratory equipment, vascular stents and shunts, absorbent materials and separation membranes, three-dimensional structures, and some other devices in patent document US20100261799A1. Fulvic acid and sericin solutions are not used and no information has been provided about the use of the produced packaging material in the food industry in the said document.

The patent document EP2271437B1 mentions the formation of droplets of particles or matter to produce paper, cardboard, filter, or microfibrillar cellulose, e.g. for plastic reinforcements, the provision of the foamed environment and its electrostatic processing. Said invention is related to a method of forming particles or droplets by electrostatic treatment.

It has been observed in the patent research that the sericin/fulvic acid pair used in the invention has never been used in the preparation of active packaging by coating in the form of nanoparticles on paper packaging material by electrospray method.

Innovative packaging applications are required since the packaging and methods available in the prior art are not sufficient to prevent microbial growth/degradation in foods by preserving quality, freshness, and safety.

Summary of the Invention

The invention is related to the production of a cellulose-based active packaging using paper, a biodegradable, sustainable, recyclable, renewable, and cheap packaging material. As an alternative to existing applications in the form of coating with natural and synthetic waxes, it is not consumed with the product and does not have any negative effect on human health even if it is transferred to food and it has a number of beneficial effects. For example, it has been stated that sericin is a suitable material in cell culture and tissue engineering thanks to its antioxidant properties, moisturizing ability, and mitogenic effect in mammalian cells; in the field of medicine, cosmetics, and biotechnology with the evidence of its important biological activities; for producing edible films, thanks to its anti-browning properties (polyphenol oxidase inhibitor) in fruits, and that it can be used for quality improvement of minimally processed fruits and vegetables and in the food industry (Lamboni et al., 2015; Thongsook and Tiyaboonchai, 2011). Sericin is also advantageous for the food industry considering that it is non-toxic and reduces serum cholesterol and free fatty acids (Ghosh et al., 2017).

The ability of fulvic acid to form a chelate with metals indicates that it can produce many beneficial effects, including antioxidant activity, stress management, anti-inflammatory activities, and antimicrobial properties (Gao, 2017). It is stated that fulvic acid can form a film in the mucus epithelium of the gastrointestinal tract and protect against infections and toxins, thus improving the use of nutrients in animal feed (Islam et al., 2005; Trekova et al., 2005). In addition, fulvic acid has antimicrobial and anti-inflammatory properties (Van Rensburg et al., 2001).

Fulvic acid is used as an active agent during the production of packaging material of the invention; sericin, which has antioxidant, antimicrobial, and anti-browning (polyphenol oxidase enzyme inhibitor) properties is used as a carrier environment.

In addition, this packaging produced by the invention method will not leave a different smell and taste in the products thanks to being odorless and tasteless and thus will not cause a change in the unique sensory properties of the food. A water-based solution containing sericin and fulvic acid which are organic -based, food-compatible, and cheap components are applied on the paper, which is the packaging material by electrospray method, in order to give antimicrobial properties. An innovative food packaging is produced by the effective application of the electrospray method in small quantities without changing the main structure of the packaging.

When comparing the electrospray method used in the invention with the spraying or coating of the surface with the film; smaller droplets are obtained with the electrospray method compared to the other methods and the process is carried out with less solution. Droplets with almost equal size distribution and a diameter ranging from nanometers to micrometers can be produced by this method (Jaworek and Sobczyk, 2008). The prior art does not include the coating of nano- sized particles containing sericin and fulvic acid on the paper surface by electro spraying.

In addition, directing the droplets obtained by the electrospray technique to the collection plate with the effect of the electric field provides high accumulation efficiency (Pareta and Edirisinghe, 2006). The electrospray method is a promising application for producing high- quality layers and films thanks to these stated advantages. It allows fine droplets to be formed having a narrow particle size distribution and in micrometer and sub-micrometer sizes. The electrostatic forces distribute droplets homogeneously in the space between the sprayer and the substrate. The surface area is reduced with the reduction of particles and a wider antimicrobial effect is achieved with the application of a small amount of solvent, and more effective bioactivity is obtained. There is no need to apply any additional mechanical energy other than the electric field for the atomization of the liquid in the electrospray process and it is a cheaper method compared to methods such as chemical or physical vapor deposition (Jaworek, 2007).

Avocado, lemon, and pear, which have not undergone any coating process, can be stored by wrapping them in the produced packaging. The use of the active packaging in the packaging of selected foods, obtained by applying fulvic acid and sericin on the paper packaging material with electrospray method is first performed within the scope of this invention. The invention material is suitable for all food products in which paper packaging is used.

The reason for the wrapping process of the fruits is to increase the surface contact and to provide antimicrobial effect in a wider area although it is predicted that the mechanism of action in the application of the sericin/fulvic acid coating process will be through contact.

When the invention is compared to the patent document EP2271437B 1 it is common that the method used is an electrostatic method, but the said patent and the invention differ in that the solutions used in the invention and the active packaging production are the main objectives. In addition, in this patent, which is thought to be similar, the paper surface is not be covered with nanosized particles containing sericin/fulvic acid. In addition, there is no specified application area such as storing by coating fruits as an area of use.

In addition, the sericin protein, which is a textile waste and use of which in biomedical, biotechnology, and food industry is gaining importance and which is also known to have positive health-related effects is used while producing the packaging material of the invention; thus, wastes in the textile industry can be utilized. However, the fulvic acid used in the coating of the paper packaging material of the invention has positive effects on human health as well as its ability to form a chelate with heavy metals, antioxidant effect, antiinflammatory activity, and antimicrobial properties.

Packaging papers made of 100% cellulose can be used in the invention. On the packaging material used in the experiments within the scope of the invention, MG Kraft paper (its commercial name is super MG Kraft wrapping paper, it is of low weight (weighing 17-18 g/m ), made of 100% cellulose, durable, and used especially in the wrapping and preservation of fruits and vegetables) the solution containing sericin and fulvic acid are electrosprayed, and the active packaging is produced by coating the said paper with the formed nanoparticles.

The invention ensures the preservation of the quality properties and extending the consumability period of the fruits with the packaging material with antimicrobial properties as a solution to the technical problem of how to prevent food degradation after packaging. It is aimed to delay the food degradation that occurs after the packaging of foods thanks to the active packaging material produced by the invention. While doing so, paper was chosen as a packaging material in order to reduce the use of packaging materials such as plastic in foods. Paper is also one of the cheaper and more reliable materials used instead of expensive raw materials and is one of the most important packaging materials of the future with renewable and sustainable production.

An antimicrobial packaging material is produced by coating the paper, as an alternative to the antimicrobial substances used in the industry, with solutions of fulvic acid and sericin being new, cheap, natural and having non-toxic antimicrobial properties for the first time with the electrospray method in order to provide a nano-sized coating. The resulting packaging contains components which are natural, biodegradable, biocompatible and have no negative effects on health, on the contrary have positive health effects.

The invention includes the development of an innovative, biodegradable, environmentally friendly, cheap, functional packaging due to these properties described. The electrospray method was chosen to provide more effective bioactivity (antioxidant and antimicrobial activity) by forming nanosized particles in order to increase the surface area for the application of the fulvic acid and sericin which are cheap, natural and have not been used together before, to the packaging material with the invention.

The invention provides a cellulose-based active packaging alternative to the existing applications in the form of coating with natural and synthetic waxes using paper, which is a non-toxic, biodegradable, sustainable, recyclable, renewable, and cheap packaging material. Therefore, it meets the need for innovative packaging applications that can prevent microbial growth/degradation by preserving the quality, freshness, and safety of foods.

Definitions of the Figures Describing the Invention

Figure 1: Electro spray assembly

Figure 2: Structure of the paper packaging sprayed with the solution of fulvic acid/sericin and, as an example, wrapping the pear sample with this packaging material

Figure 3: Results of Atomic Force Microscope (AFM)

Figure 4: Sizes of the sericin/fulvic acid nanoparticles obtained by the electrospray method

Elements Constituting the Invention

1. Syringe pump

2. Positioning system

3. Solution containing fulvic acid and sericin

4. Needle tip

5. Voltage source

6. Eight

7. Ground electrode

8. Collection surface (copper plate collector)

9. Paper packaging

10. Sled system Detailed Description of the Invention

The invention covers the active packaging obtained by applying fulvic acid and sericin on paper packaging material by using the electrospray method and the production method of this packaging.

Fulvic acid is obtained from leonardite samples, which are commercially available and an organic material. The obtained fulvic acid is used as an active agent after the purification process; sericin which has antioxidant, antimicrobial, and anti-browning (polyphenol oxidase enzyme inhibitor) properties is used as a carrier environment. Fulvic acid can also be commercially available; however, it is recommended to use it by purifying from leonardite since the fulvic acids sold cheaply in the market have low purity, and the ones having high purity can be supplied by chemical supply companies, have long arrival times from abroad and are expensive.

The particle size distribution, roughness, and antimicrobial and antioxidant capacity were measured in response by changing the voltage, flow rate, fulvic acid/sericin concentration, and the fulvic acid/sericin ratio by weight (w/w) in the solution in the electrospray experiments and optimized with the experimental design. The packaging (with homogeneous coating, maximum antimicrobial, and antioxidant capacity) obtained by selecting the most appropriate parameters was used in the packaging of avocado, pear, and lemon, and the effectiveness of the packaging and the changes (color, texture, and microbial load) were determined that would occur with the analysis during the storage of the product. The invention packaging is suitable for all food products in which paper packaging is used.

The system required to produce the product consists of the vertical electrospray assembly shown in Figure 1, the syringe pump (1), the 0-50 kV high-voltage source (5) (the applied voltage is preferably, but not limited to, 20 kV, with being between 17-23 kV), the ground electrode (7), the collection surface (copper plate collector) (8), the paper packaging (9) placed on this plate, and a slide system (10) moving in the xyz plane on which this packaging is placed. The collection surface (copper plate collector) is preferably, but not limited to, 25x45 cm in size. A sterile syringe and straight-cut syringe tip are connected to the syringe pump to supply the liquid to be sprayed. The electrical voltage is applied by connecting the electrode connected to the high voltage source (5) to the metal needle tip (4) using a crocodile. The electrospray method is applied by connecting the electrical voltage, the electrode connected to the high voltage source (5), to the metal needle tip (4) using a crocodile. 2 ground ends taken from the high voltage source (5) are attached to the collection surface (copper plate collector) (8) with two crocodile in order to ground the collection surface (copper plate collector) (8). In the existing system, a thin paper packaging (9) that can be used as a packaging is placed on the collection surface (copper plate collector) and electrospray is performed on it.

The electrospray device/assembly of the invention providing for producing the paper packaging of the invention comprises:

• Syringe pump (1) for supplying the liquid to be sprayed,

• Voltage source (5) providing electrical voltage,

• The ground electrode (7), which allows the sprayed liquid to be directed to the target point,

• The collection surface (8), which is the target region where the sprayed liquid is directed, and paper packaging (9) located on the collection surface (8),

• Sled system (10) that can move in xyz plane enabling homogeneous coating.

A detailed description of all the elements that make up the electrospray assembly mentioned in Figure 1 is as follows.

1. Syringe pump: It is used to ensure slow and controlled supplying of the solution to be sprayed during the electrospray process.

2. Positioning system: It is the system required to keep the syringe stationary.

3. Solution containing fulvic acid and sericin: It is the solution sprayed to provide the paper packaging with antimicrobial properties.

4. Needle tip: It is necessary to spray the solution with the created electrical field and to form the Taylor cone.

5. Voltage source: It ensures that the electrical field is created with the electrical current given to the solution and that electrical loading occurs on the surface of the solution. The electrostatic forces are equalized to the surface tension forces and the drops take the form of cones (Taylor Cone) when the potential difference applied reaches the threshold value.

6. Light: It is used to see the Taylor Cone formed in the spraying process.

7. Ground electrode: The liquid/droplets are drawn towards the collection surface with the grounding electrode which allows the sprayed liquid to be directed to the target point.

8. Collection surface (copper plate collector): It is the target area where the liquid/droplets moving with the grounding are directed.

9. Paper packaging: The target area where the droplets are intended to reach is the surface of the paper packaging material.

10. Sled system: It allows the surface to be coated more homogeneously with a moving platform in the xyz planes in order to provide a more homogeneous coating on the surface and to be used effectively in food packaging applications.

The paper packaging containing sericin/fulvic acid nanoparticles obtained as a result of the electrospray process and the use of this packaging for pear fruit as an example are specified as shown in Figure 2.

Particles containing sericin-fulvic acid in the range of 50-100 nm were obtained in the studies conducted with electrospray (Figure 4). Nanoparticles are synthesized thanks to the fact that the electrospray technology is based on the formation of droplets from the accumulation of solid residues under the electric field and that the formation and size of these droplets can be controlled by optimization of parameters such as voltage, flow rate, and distance between the needle and the collector. Homogeneous distribution of sericin/fulvic acid nanoparticles on the paper is ensured and the packaging (9) is provided with antimicrobial properties by electro spraying process applied to the paper packaging (9) placed on the collection surface (8).

It is also possible to optimize the particle formation by considering the solution (solution containing Fulvic acid and sericin) and the electrospray process parameters in order to cover it on paper in the desired properties in food packaging applications. The ratio of fulvic acid/sericin was prepared in ratios of 1:1 and 1:4 by weight, with the total amount of fulvic acid and sericin being 3-8 g/10 ml (weight by volume) in solvent (water) in the preliminary tests. Fulvic acid and sericin are weighed in the ratios of 1: 1 and 1:4 and distilled water is added to them and the solution is prepared by stirring in a magnetic stirrer. The ratio of fulvic acid/sericin is prepared in a ratio of 1:1 by weight, with total amount of sericin and fulvic acid (g)/water (ml) of the optimum solution content being 7g/10ml. For example, if the total soluble substance concentration is 8 g/10 ml, there should be 4 g of fulvic acid and 4 g of sericin in order for the ratio of fulvic acid/sericin to be 1:1 by weight, and the total soluble substance concentration will be 8 g/10 ml. For example, if the total soluble substance (fulvic acid and sericin) concentration is 5 g/10 ml, 1 gram of fulvic acid and 4 grams of sericin are dissolved in 10 ml of water, the ratio of fulvic acid/sericin is 1:4 by weight, and the total soluble substance concentration is 5 g/10 ml.

In addition, the surface is allowed to be coated more homogeneously with a moving platform (Sled system (10)) in order to provide a more homogeneous coating on the surface and to be used effectively in food packaging applications. Electrospray process parameters applied in the invention are determined such that the Spray Flow Rate is, but not limited to, between 0.25-0.75 ml/h, preferably 0.5 ml/h. The distance between the needle tip (4) and the collection surface (8) is determined to be, but not limited to, between 14-20 cm, preferably 17 cm. The results of the sizes of sericin/fulvic acid nanoparticles obtained by using the Atomic Force Microscope (AFM) obtained as a result of the preliminary test are shown in Figures 3 and 4.

Homogeneous distribution of nanoparticles on paper is provided by a mechanism/sled system (10) that can move in the xyz plane.

The method of operation of the invention device is as follows:

• Obtaining fulvic acid,

• Preparing solution (3) containing fulvic acid and sericin,

• Drawing the solution (3) containing fulvic acid and sericin into the syringe,

• Attaching the syringe to syringe pump (1) and selecting the flow rate,

• Adjusting the distance between the needle tip (4) and the collection surface (8),

• Placing the paper packaging (9) on the collection surface (8), • Adjusting the voltage from voltage source (5) and spraying the solution (3) containing fulvic acid and sericin on the paper packaging (9) by opening the syringe pump (1).