PL247922B1 - Coating solution, an edible biopolymer coating for extending the food shelf life and method for producing a coating-forming solution - Google Patents

Abstract

The subject of the application is a film-forming solution containing chitosan in the amount of 1.8% to 2.0% by weight of the mass of 1.9% to 2.1% of acetic acid used to dissolve chitosan, stirred for approx. 3 hours at a temperature of 70°C to 90°C, in an amount of 43.5% to 55.0% of the total mass of the film-forming solution, furcellaran dissolved in distilled water in the amount of 0.2% to 1.0% by weight of the distilled water used and left to swell for 0.9 - 1.1 hours and then dissolved under stirring at a temperature of 180°C to 220°C until a homogeneous, clear film-forming furcellaran solution is obtained and in the next step the pH of the prepared solution is adjusted to a value of pH 3 to pH 4 by dropwise addition of 10% hydrochloric acid in the amount needed to obtain a solution pH of from pH 3 to pH 4, in an amount of from 43.5% to 55.0% of the total weight of the film-forming solution, wherein the chitosan solution is mixed with a heated furcellaran solution by dropwise adding the furcellaran solution to the chitosan solution, and glycerol in an amount of from 0.5% to 1.5% of the total weight of the film-forming solution, added to the furcellaran solution and the chitosan solution during mixing. The subject of the application also includes an edible biopolymer coating for extending the shelf life of food and a method for obtaining a film-forming solution for producing an edible biopolymer coating.

Description

Description of the invention

The invention concerns a film-forming solution for extending the shelf life of food and a method for producing the film-forming solution. The film-forming solution can be applied to a product, particularly a food product, in liquid form by pouring, dipping, or spraying. In turn, an edible biopolymer coating produced from the film-forming solution for extending the shelf life of food, for example, in the form of a biopolymer film, can be used as packaging for products, including food products. The invention may find application in the food industry as a method for preserving perishable food products.

Consumer demand for minimally processed food without artificial additives necessitates the search for new natural sources of preservatives and active packaging that extend the shelf life of food products. A film-forming solution and the active, edible biopolymer coating produced from it, described below, may be the answer.

Edible, active coatings containing chitosan and carrageenan are known.

Edible, active coatings containing furcellaran are known, however, there is no information regarding coatings or solutions with a furcellaran-polysaccharide complex. In known embodiments, to obtain a coating solution, furcellaran was mixed with whey protein (Pluta-Kubica, Jamróz, Kawecka, Juszczak, & Krzyściak, 2019), gelatin (Jamróz, Kulawik, Krzyściak, Talaga-Ćwiertnia, & Juszczak, 2019), or gelatin hydrolysate (Jamróz et al., 2021), which was used to obtain biopolymer films.

Consumer demand for minimally processed food without artificial additives necessitates the search for new natural sources of preservatives and active packaging that extend the shelf life of food products. The active, edible biopolymer coating presented in the following invention may provide an answer to this need.

Furcellaran, known in the art, is an anionic polysaccharide obtained from the red alga Furcellaria lumbricalis, and its structural and functional properties are similar to κ-carrageenan. Chitosan, in turn, is a polysaccharide with antimicrobial properties, which has been proposed as an effective coating agent for many raw materials and foodstuffs. Chitosan is obtained from chitin, resulting in a biodegradable polymer with wide applications in medicine, veterinary medicine, cosmetics, and environmental protection. In the proposed coating, chitosan acts as an antimicrobial agent.

The present invention aims to create a film-forming solution for producing an edible biopolymer coating for extending the shelf life of food. Furthermore, the present invention aims to provide a method for preparing a film-forming solution for producing an edible biopolymer coating for extending the shelf life of food.

The idea of the invention is a film-forming solution containing furcellaran for the production of an edible biopolymer coating for extending the shelf life of food, characterized in that, in addition to furcellaran dissolved in distilled water in an amount of 0.2% to 1.0% by weight of the distilled water used and left to swell for 0.9-1.1 hours and then dissolved under stirring at a temperature of 180°C to 220°C until a homogeneous, clear film-forming solution of furcellaran is obtained and in the next step the pH of the prepared solution is adjusted to a value of pH 3 to pH 4 by dropwise addition of 10% hydrochloric acid in an amount necessary to obtain a pH of the solution of pH 3 to pH 4, in an amount of 43.5% to 55.0% of the total weight of the film-forming solution, the film-forming solution contains chitosan in an amount of 1.8% to 2.0%. by weight of the mass from 1.9% to 2.1% of acetic acid, used to dissolve chitosan, stirred for approx. 3 hours at a temperature from 70°C to 90°C, in an amount from 43.5% to 55.0% of the total weight of the film-forming solution, mixed with a heated furcellaran solution by dropwise adding the furcellaran solution to the chitosan solution, and glycerol in an amount from 0.5% to 1.5% of the total weight of the film-forming solution, added to the furcellaran solution and the chitosan solution while stirring.

The idea of the invention is also a method of obtaining a film-forming solution for the production of an edible biopolymer coating for extending the shelf life of food, characterized in that a chitosan solution is prepared individually in the amount of 1.8% to 2.0% by weight of acetic acid from 1.9% to 2.1% used to dissolve chitosan, which is stirred for approx. 3 hours at a temperature of 70°C to 90°C, in the amount of 43.5% to 55.0% of the total weight of the film-forming solution, furcellaran dissolved in distilled water in the amount of 0.2% to 1.0% by weight of the water used and initially left to swell for 0.9-1.1 hours and then dissolved while stirring at a temperature of 180°C to 220°C until a homogeneous, clear film-forming furcellaran solution is obtained and in the next step adjusted to a pH in the range of 3 to pH 4, by dropwise addition of 10% hydrochloric acid in an amount necessary to obtain a solution pH of from pH 3 to pH 4, in an amount from 43.5% to 55.0% of the total weight of the film-forming solution, wherein the chitosan solution is mixed with a previously prepared and heated furcellaran solution, by dropwise addition of the furcellaran solution to the prepared chitosan solution, and then glycerol is added in an amount from 0.5% to 1.5% of the total weight of the film-forming solution, while mixing the furcellaran solution and chitosan solution, and further mixing for another 8-15 minutes. Mixing may be carried out at 1000 x g. The expression 1000 x g describes the acceleration force applied to the sample in a centrifuge, which is measured as a multiple, in this case 1000 times, of the standard acceleration due to gravity on the Earth's surface or the acceleration due to Earth's gravity. With vigorous mixing, mixing can be carried out up to 10,000 x g.

The subject of the invention is shown in the embodiment examples in the drawing, in which Fig. 1 shows a block diagram of one of the methods for preparing a chitosan solution, Fig. 2 shows a block diagram of one of the methods for preparing an aqueous solution of furcellaran, and Fig. 3 shows a block diagram of one of the methods for preparing a film-forming solution for producing an edible biopolymer coating.

In order to obtain a film-forming solution for the production of an edible biopolymer coating, two solutions are prepared individually: a chitosan solution and an aqueous furcellaran solution.

Figure 1 shows a flow chart of one method for preparing a chitosan solution. In step 20, chitosan is dissolved in 2% acetic acid, or 1.9% acetic acid, or 2.1% acetic acid. In one example, 1.8% by weight of acetic acid is dissolved in one of the concentrations of acetic acid given above. In another example, 2.0% by weight of acetic acid is dissolved in one of the concentrations of acetic acid given above, and in yet another example, an amount of chitosan selected from the range of 1.8% to 2.0% by weight of acetic acid is dissolved in one of the concentrations of acetic acid given above. Then, in step 21, the solution is stirred for approximately 3 hours, in one example at 70°C, in another example at 90°C, preferably at 80°C. The proportion of the chitosan solution in the total mass of the film-forming solution is from 43.5% to 55.0%.

Fig. 2 shows a flow chart of one method for preparing an aqueous furcellaran solution. In step 40, the furcellaran is mixed with distilled water. In one example, the furcellaran is mixed in an amount of 0.2% by weight of the distilled water used, in another example, the furcellaran is mixed in an amount of 1.0% by weight of the distilled water used, preferably, the furcellaran is mixed in an amount of 0.6% by weight of the distilled water used. After this, in step 41, the aqueous furcellaran solution is allowed to swell, in one example for 0.9 hours, in another example for 1.1 hours, preferably for 1 hour. Then, in step 42, it is dissolved with stirring, in one example at 180°C, in another example at 220°C, preferably at 200°C, to obtain a homogeneous, clear film-forming solution. In the next step 43, the pH of the furcellaran solution is adjusted to a value of pH 3 to pH 4 by dropwise addition of 10% hydrochloric acid in an amount necessary to obtain a solution pH of pH 3 to pH 4. In one example, 15 drops of 10% HCl are added, in another example, 17 drops of 10% HCl are added, preferably 16 drops of 10% HCl are added. Adding HCl to solutions to obtain a desired solution pH is well known in the art. Various publications indicate that after adding HCl to the solution, the pH of the solution is checked and HCl is added, continuously checking the pH, until the solution pH is adjusted to the desired pH. Measuring the pH of a solution is easier than calculating how much HCl needs to be added to adjust the solution pH to the desired pH. The share of the furcellaran aqueous solution in the total mass of the film-forming solution ranges from 43.5% to 55.0%.

Fig. 3 shows a flow chart of one method for preparing a film-forming solution for producing an edible active biopolymer coating. After starting in step 50, in step 51 the previously prepared chitosan and furcellaran solutions are mixed by dropwise adding a hot furcellaran solution to the chitosan solution while stirring vigorously. Glycerol is added to the resulting mixture of furcellaran and chitosan solutions in step 52, in one example in an amount

0.5% of the total weight of the film-forming solution, in another example in an amount of 1.5% of the total weight of the film-forming solution, preferably in an amount of 1.0% of the total weight of the film-forming solution, and in step 53 mixed, in one example for 8 minutes, in another example for 15 minutes, preferably for 10 minutes, until the formation of the film-forming solution to form the edible active biopolymer coating is completed in step 54.

In one embodiment, the film-forming solution prepared by the method according to the invention contains furcellaran dissolved in distilled water in an amount of 0.2% by weight of the distilled water used and left to swell for 0.9-1.1 hours and then dissolved under stirring at a temperature of 180°C to 220°C until a homogeneous, clear film-forming furcellaran solution is obtained and the pH of the prepared solution is adjusted in the next step to a value of pH 3 to pH 4 by dropwise addition of 10% hydrochloric acid in an amount necessary to obtain a pH of the solution of pH 3 to pH 4, after dissolving in an amount of 45% of the total weight of the film-forming solution, chitosan in an amount of 1.8% to 2.0% by weight of the weight of 2% acetic acid used to dissolve chitosan, stirred for 3 hours at a temperature of 70°C to 90°C, after dissolving in an amount of 54.5% of the total weight of the film-forming solution, mixed with the heated furcellaran solution by dropping the furcellaran solution into the chitosan solution, and glycerol in an amount of 0.5% of the total weight of the film-forming solution, added to the furcellaran solution and the chitosan solution while stirring.

In another embodiment, the film-forming solution prepared by the method according to the invention contains furcellaran dissolved in distilled water in an amount of 1.0% by weight of the distilled water used and left to swell for 0.9-1.1 hours and then dissolved under stirring at a temperature of 180°C to 220°C until a homogeneous, clear film-forming furcellaran solution is obtained and the pH of the prepared solution is adjusted in the next step to a value of pH 3 to pH 4 by dropwise addition of 10% hydrochloric acid in an amount necessary to obtain a pH of the solution of pH 3 to pH 4, after dissolving in an amount of 55.0% of the total weight of the film-forming solution, chitosan in an amount of 1.8% to 2.0% by weight of the weight of 2% acetic acid used to dissolve chitosan, stirred for approx. 3 hours at a temperature of 70°C to 90°C, after dissolving in an amount of 43.5% of the total weight of the film-forming solution, mixed with the heated furcellaran solution by dropwise adding the furcellaran solution to the chitosan solution, and glycerol in an amount of 1.5% of the total weight of the film-forming solution, added to the furcellaran solution and chitosan solution while mixing. The edible biopolymer coating is obtained by evaporating water from the film-forming solution until the edible moisture content of the biopolymer coating is no more than 15%.

The subject of the invention is further described in the following embodiment examples.

Example 1

To obtain a film-forming solution for the production of an edible biopolymer coating, two solutions are prepared individually: a chitosan solution and an aqueous furcellaran solution. 0.9 g of chitosan is dissolved in 40 ml of 2% acetic acid. This solution is stirred at 80°C for approximately 3 hours. Next, 0.1 g of furcellaran is dissolved in 50 ml of distilled water and allowed to swell for 1 hour. It is then dissolved with stirring at 200°C to obtain a homogeneous, clear film-forming solution. Next, the pH of the furcellaran solution is adjusted to between pH 3 and pH 4 by dropwise addition of 10% hydrochloric acid, in the amount needed to achieve the desired pH. Once the desired pH is achieved, the hot furcellaran solution is added dropwise to the chitosan solution with vigorous stirring. 0.5 ml of glycerol is added to the above mixture of furcellaran and chitosan solutions and mixed for another 15 minutes.

Example 2

To obtain a film-forming solution for the production of an edible biopolymer coating, two solutions are prepared individually: a chitosan solution and an aqueous furcellaran solution. 0.7 g of chitosan is dissolved in 50 ml of 2% acetic acid. This solution is stirred at 90°C for approximately 3 hours. Next, 0.2 g of furcellaran is dissolved in 40 ml of distilled water and allowed to swell for 0.9 hour. It is then dissolved with stirring at 220°C to obtain a homogeneous, clear film-forming solution. Next, the pH of the furcellaran solution is adjusted to between pH 3 and pH 4 by dropwise addition of 10% hydrochloric acid, in the amount needed to achieve the desired pH. Once the desired pH is achieved, the hot furcellaran solution is added dropwise to the chitosan solution with vigorous stirring. 1.5 ml of glycerol is added to the above mixture of furcelleran and chitosan solutions and mixed for another 11 minutes.

Example 3

To obtain a film-forming solution for the production of an edible biopolymer coating, two solutions are prepared individually: a chitosan solution and an aqueous furcellaran solution. 0.9 g of chitosan is dissolved in 60 ml of 2% acetic acid. This solution is stirred at 80°C for approximately 3 hours. Next, 0.3 g of furcellaran is dissolved in 60 ml of distilled water and allowed to swell for 1.1 hours. It is then dissolved with stirring at 180°C to obtain a homogeneous, clear film-forming solution. Next, the pH of the furcellaran solution is adjusted to between pH 3 and pH 4 by dropwise addition of 10% hydrochloric acid, in the amount needed to achieve the desired pH. Once the desired pH is achieved, the hot furcellaran solution is added dropwise to the chitosan solution with vigorous stirring. 1 ml of glycerol is added to the above mixture of furcellaran and chitosan solutions and mixed for another 8 minutes.

In each of the examples given above, the obtained solution may be transferred directly onto a food product or poured onto a plate or Petri dish where, after drying and leaving to dry in a fume hood at room temperature for 2 days, it takes the form of a film whose moisture content does not exceed 15%, and whose size is determined using one of the methods known in the art.

The following is an example of the application of the claimed invention to pork loin protected with a film-forming solution. In this example, fresh pork loin was first divided into three equal parts using a sterile knife. One part, designated as the blank sample, was immersed in the film-forming solution prepared according to Example 1 using sterile anatomical laboratory tweezers for 3 seconds and then transferred to a sterile PET package with a lid. The second part, designated as the control sample, was transferred directly to the sterile PET package with a lid without being immersed in the solution. The third part, designated as the blank sample, was placed in a sterile PET package and submitted for microbiological testing to determine the initial contamination of the product. The coated sample and the control sample were stored for 11 days in a refrigerated unit at 4°C. After this time, the samples were subjected to microbiological analysis. Microbiological analyses involved determining the total number of mesophilic aerobic microorganisms, according to the ISO 4833-1:2013 standard. The test was repeated three times using pork loins from different packages and batch numbers. Initial contamination of the pork loin on the day of sample preparation in the blank sample averaged 2.17 ± 0.47 log CFU/g. After 11 days of refrigerated storage, the total microbial count in the control loin was 6.70 ± 1.62 CFU/g, while in the pork loin with the active coating it was 3.92 ± 0.81 CFU/g.

Claims (2)

1. A film-forming solution containing furcellaran for the production of an edible biopolymer coating for extending the shelf life of food, characterized in that, in addition to furcellaran dissolved in distilled water in an amount of 0.2% to 1.0% by weight of the distilled water used and left to swell for 0.9-1.1 hours and then dissolved under stirring at a temperature of 180°C to 220°C until a homogeneous, clear film-forming furcellaran solution is obtained and the pH of the prepared solution is adjusted in the next step to a value of pH 3 to pH 4 by dropwise addition of 10% hydrochloric acid in an amount necessary to obtain a pH of the solution of pH 3 to pH 4, after dissolving in an amount of 43.5% to 55.0% of the total weight of the film-forming solution, the film-forming solution contains chitosan in an amount of 1.8% to 2.0% by weight of 1.9% to 2.1% of acetic acid used to dissolve chitosan, stirred for approximately 3 hours at a temperature of 70°C to 90°C, after dissolving in an amount of 43.5% to 55.0% of the total weight of the film-forming solution, mixed with a heated furcellaran solution by dropwise adding the furcellaran solution to the chitosan solution, and glycerol in an amount of 0.5% to 1.5% of the total weight of the film-forming solution, added to the furcellaran solution and chitosan solution while stirring. 2. A method for obtaining a film-forming solution for producing an edible biopolymer coating for extending the shelf life of food, characterized in that a chitosan solution is prepared individually in the amount of 1.8% to 2.0% by weight of acetic acid used to dissolve chitosan, which is stirred for about 3 hours at a temperature of 70°C to 90°C, in the amount of 43.5% to 55.0% of the total weight of the film-forming solution, furcellaran dissolved in distilled water in the amount of 0.2% to 1.0% by weight of the water used and initially left to swell for 0.9-1.1 hours and then dissolved under stirring at a temperature of 180°C to 220°C until a homogeneous, clear film-forming furcellaran solution is obtained and in the next step adjusted to a pH in the range of 3 to pH 4, by dropwise addition of 10% acid in an amount necessary to obtain a pH of the solution from pH 3 to pH 4, in an amount from 43.5% to 55.0% of the total weight of the film-forming solution, wherein the chitosan solution is mixed with a previously prepared and heated furcellaran solution, by dropwise addition of the furcellaran solution to the prepared chitosan solution, and then glycerol is added in an amount from 0.5% to 1.5% of the total weight of the film-forming solution, while mixing the furcellaran solution and the chitosan solution, and further mixing for another 8-15 minutes.