Gelatin or pectin based antimicrobial surface coating material

Abstract

The present invention relates to a gelatin or pectin based antimicrobial surface coating material. In the present invention, boron compounds are mixed with gelatin or pectin and a surface coating material in the form of a film is obtained. The said coating material can be used in all packaging industry requiring hygiene particularly in food industry. The invention enables packages to be antifungal, anticandidal and antibacterial.

Claims

1. A gelatin-based antimicrobial surface coating material, comprising a gelatin and a boron compound, the boron compound comprising boric acid, sodium pentaborate, or disodium octaborate; the boron compound being cross-linked with the gelatin, and wherein the boron compound is 5% to 15% by mass of the boron compound cross-linked gelatin.

2. The gelatin-based antimicrobial surface coating material according to claim 1, comprising 5% to 15% by mass of sodium pentaborate.

3. The gelatin-based antimicrobial surface coating material according to claim 1, comprising 5% to 15% by mass of disodium octaborate.

4. The gelatin-based antimicrobial surface coating material according to claim 1, possessing antibacterial properties against Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa bacteria.

5. The gelatin-based antimicrobial surface coating material according to claim 1, possessing antibacterial properties against Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa bacteria.

6. The gelatin-based antimicrobial surface coating material according to claim 4, possessing anticandidal properties against Candida albicans yeast.

7. The gelatin-based antimicrobial surface coating material according to claim 5, possessing anticandidal properties against Candida albicans yeast.

8. The gelatin-based antimicrobial surface coating material according to claim 6, possessing antifungal properties against Aspergillus niger fungus.

9. The gelatin-based antimicrobial surface coating material according to claim 7, possessing antifungal properties against Aspergillus niger fungus.

10. The gelatin-based antimicrobial surface coating material according to claim 1, wherein the gelatin-based antimicrobial surface coating material forms a single layer, the gelatin and the boron compound being in the same single layer.

11. The gelatin-based antimicrobial surface coating material according to claim 1, comprising 10% to 15% by mass of boric acid.

12. The gelatin-based antimicrobial surface coating material according to claim 1, comprising 10% to 15% by mass of sodium pentaborate.

13. The gelatin-based antimicrobial surface coating material according to claim 1, comprising 10% to 15% by mass of disodium octaborate.

14. The gelatin-based antimicrobial surface coating material according to claim 1, comprising 10% by mass of boric acid.

15. The gelatin-based antimicrobial surface coating material according to claim 1, comprising 10% by mass of sodium pentaborate.

16. The gelatin-based antimicrobial surface coating material according to claim 1, comprising 10% by mass of disodium octaborate.

17. The gelatin-based antimicrobial surface coating material according to claim 1, wherein the gelatin-based antimicrobial surface coating material is an antimicrobial material in packaging industry requiring hygiene.

18. The gelatin-based antimicrobial surface coating material according to claim 1, wherein the gelatin-based antimicrobial surface coating material is in a form of a liquid or powder.

19. The gelatin-based antimicrobial surface coating material according to claim 1, wherein the gelatin-based antimicrobial surface coating material is an antimicrobial material to protect fruits and vegetables via spraying or immersion.

20. The gelatin-based antimicrobial surface coating material according to claim 1, the gelatin-based antimicrobial surface coating material forming a sealed barrier around a biodegradable substance to prevent exposure or release of the biodegradable substance to an environment external to the barrier, the sealed barrier being air-tight and liquid-tight.

Description

DETAILED DESCRIPTION OF THE INVENTION

(1) Within the scope of the present invention, film strips, which will be used as antimicrobial surface coating material, are produced by combining boron compounds with gelatin or pectin based chemicals.

(2) The “Gelatin or Pectin Based Antimicrobial Surface Coating Material” developed to fulfill the objective of the present invention is illustrated in the accompanying figures, in which:

(3) FIG. 1 is a view of the layout of the boron-containing film in the petri dish.

(4) FIG. 2 is a view of the antifungal activity of the 15% boron compound-doped gelatin films on the fungus Aspergillus niger.

(5) FIG. 3 is a view of the antifungal activity of the 10% boron compound-doped gelatin films on Candida albicans yeast.

(6) FIG. 4 is a view of the antibacterial activity of the 5% boron compound-doped gelatin films on Pseudomonas aeruginosa bacteria.

(7) FIG. 5 is a view of the antibacterial activity of the 10% boron compound-doped gelatin films on Staphylococcus aureus bacteria.

(8) FIG. 6 is a view of the antibacterial activity of the 10% boron compound-doped pectin films on Staphylococcus aureus bacteria.

(9) FIG. 7 is a view of the antifungal activity of the 10% boron compound-doped pectin films on the fungus Aspergillus niger.

(10) FIG. 8 is a view of the antibacterial activity of the 15% boron compound-doped pectin films on Pseudomonas aeruginosa bacteria.

(11) FIG. 9 is a SEM view of the pectin based film not containing any additives.

(12) FIG. 10 is a SEM view of the pectin based film containing 15% Boric Acid.

(13) FIG. 11 is a SEM view of the pectin based film containing 10% Disodium octaborate.

(14) FIG. 12 is a SEM view of the pectin based film containing 5% Sodium Pentaborate.

(15) FIG. 13 is a SEM view of the gelatin based film not containing any additives.

(16) FIG. 14 is a SEM view of the gelatin based film containing 10% Boric Acid.

(17) FIG. 15 is a SEM view of the gelatin based film containing 5% Disodium octaborate.

(18) FIG. 16 is a SEM view of the gelatin based film containing 15% Sodium Pentaborate.

(19) FIG. 17 is a view of the viscosity of the gel solutions comprising pectin+boron derivatives according to changing shear rate.

(20) FIG. 18 is a view of the viscosity of the gel solutions comprising gelatin+boron derivatives according to the changing shear rate.

(21) The experimental studies conducted for the method of obtaining antimicrobial coating material by using boron compounds are as follows.

EXPERIMENTAL STUDIES

(22) Film Production

(23) Gelatin and low-methoxyl pectin-based films were prepared by solvent casting method. For preparation of the gelatin films, 3 g glycerol (used as the plasticizer) and 10 g powder gelatin were dissolved in 97 mL double distilled water (ddw) under stirring at 700 rpm for 30 minutes at 50° C. At the same time, 5% to 15% by mass of boron compounds (Boric Acid or Disodium Octaborate or Sodium Pentaborate) were dissolved in 20 mL ddw and added dropwise into the gelatin solution. The obtained solution was stirred for 30 minutes and poured on a flat surface, and it was allowed to stand at room temperature for 48 hours until the solvent evaporated. This method was repeated for different boron compounds at different concentrations. For preparation of the pectin-based films, 3 g glycerol and 2 g pectin were dissolved in 70 mL ddw under stirring at 700 rpm for 30 minutes at 60° C. At the same time, 5% to 15% by mass of boron compounds (Boric Acid or Disodium Octaborate or Sodium Pentaborate) were dissolved in 15 mL ddw and added dropwise to pectin solution. A solution which was separately obtained by dissolving 0.025 g in a 15 mL ddw was added dropwise to the pectin-boron compound solution. The obtained solution was stirred for 10 minutes and poured on a flat surface, and it was allowed to stand at room temperature for 72 hours until the solvent evaporated. This method was repeated for different boron compounds at different concentrations. As a result of these procedures, antimicrobial film samples were obtained.

(24) Particularly and preferably Boric acid (BA), Disodium Octaborate (DO), and Sodium Pentaborate (SP) were used as boron compounds in the experimental studies conducted for obtaining the product of the present invention.

(25) Characterization Studies and Tests

(26) Characterization of the Developed Surfaces

(27) Surface characterization of the boron-doped antimicrobial gelatin and pectin based film surfaces of the present invention were performed. Rheological, mechanical and morphological properties of the developed film surfaces were examined comparatively with the control groups.

(28) Antimicrobial Tests

(29) Modified Disc Diffusion Method

(30) Standard NCCLS disc diffusion method [24] was used by being modified in order to determine the antimicrobial activity of boron compounds on each microorganism that is being tested. The 100 μl solution including 10.sup.8 cfu/ml bacteria, 10.sup.6 cfu/ml yeast and 10.sup.4 spor/ml fungi was prepared with new cultures and inoculated with spreading method on Nutrient Agar (NA), Sabouraud Dextrose Agar (SDA) and Potato Dextrose Agar (PDA), respectively. Antimicrobial activity tests were conducted against Staphylococcus aerus among gram-positive bacteria, Eshericia coli and Pseudomonas aeruginosa among gram-positive bacteria, Candida albicans among yeasts and Aspergillus niger among fungi. The developed film surfaces and the control groups were cut in sizes of 1×1 cm and were placed into the inoculated petri dishes. Placement of the boron-containing film materials in the petri dishes are shown in FIG. 1. The petri dishes, which were inoculated and on which modified disc diffusion method was applied, were incubated for 24 hours for bacteria and 48 hours for yeasts at 36±1° C., and for 72 hours for fungi at 25±1° C. Antimicrobial activity against microorganisms tested with modified disc diffusion method was assessed by measuring the inhibition zone (area where microorganisms do not grow). Antimicrobial activity test results of the tested boron-containing film surfaces are summarized in Table 1 and all of the tests were repeated at least twice.

(31) Experimental Results

(32) Antimicrobial Test Results:

(33) Antimicrobial activity test results of the tested boron compounds are summarized in Table 1. All tests were repeated at least twice.

(34) TABLE-US-00001 TABLE 1 Antimicrobial activity of Boric Acid (BA), Disodium Octaborate (DO), Sodium Pentaborate (SP) doped surfaces and the Control (K) group on the tested microorganisms. Biopolymer Active Concentration S. aureus P. aeruginosa E. coli C. albicans A. niger Gelatin K 0% − − − − − BA 5% + + − − + 10% + + − + + 15% + + + + + DO 5% + + − + + 10% + + − + + 15% + + + + + SP 5% + + − + + 10% + + − + + 15% + + − + + Pectin K 0% − − − − − BA 5% − − − − + 10% + + − + + 15% + + − − + DO 5% + − − − + 10% + + − + + 15% + + − + + SP 5% + − − − + 10% + + − + + 15% + + − + +

(35) Determining the Morphological Properties

(36) Morphological properties of the developed gelatin or pectin based boron-doped food film packages were determined by using a SEM device (EVO 40 series, Carl Zeiss, Germany). As a result of the SEM images, it was observed that the boron compounds were completely dispersed in the film. SEM image samples are given in FIGS. 9-15.

(37) Determining the Mechanical Properties

(38) Tensile strength of a film shows mechanical strength of it. Mechanical properties of biopolymer films are very important to be able to use them as a packaging material. Since doping with boron derivatives may change mechanical properties of the films, the produced films were subjected to physical characterization tests. Tensile strengths of the film samples of the present invention are shown in Table 2 and Table 3, respectively. The obtained results show that the negative control samples which are not doped with boron derivatives have a lower resistance in comparison to the other samples.

(39) Tensile strengths of the gelatin based films vary in the range of 8626 to 17845 grams under the effect of different boron derivatives added in different ratios. It is found that the gelatin film sample comprising 10% disodium octaborate has the highest resistance (17845 g). In view of all of the results, it is seen that disodium octaborate significantly affects resistance of the gelatin films in a positive manner. While the increase in boric acid concentration increased resistance of the gelatin films, concentrations of sodium pentaborate and disodium octaborate above 10% did not exhibit a positive influence on film resistance. It is considered that this originates from the fact that above a certain level of concentration the boron derivate accumulates at a high level between the molecules and chains thereby preventing formation of crosslinks. Since molecular weight of boric acid is lower than the other boron derivatives that are used, it is considered that the same effect cannot be observed in the films containing boric acid. Furthermore, as disodium octaborate and sodium pentaborate have a greater ionic charge than boric acid, above a certain concentration it may have caused deformation of the hydrogen bonds that strengthen the gelatin matrix.

(40) On the other hand, tensile strengths of the pectin film samples vary in the range of 963 to 2170 grams. While the highest tensile strength was obtained by addition of sodium pentaborate of 15% concentration, concentrations of disodium octaborate and boric acid above 10% did not exhibit a positive influence on the film resistance. It is considered that the changes in the tensile strengths of the pectin based films originated from the formation of crosslinks between the boron and pectic polysaccharides.

(41) TABLE-US-00002 TABLE 2 Tensile strengths of gelatin based film surfaces Ratio Tensile Strength (g) Active (%) 1 2 3 Average (g) Std. - (Control) 8626 9428 11498 9851 1482 5 12101 12348 12710 12386 306 Boric Acid 10 14234 12371 14559 13721 1181 15 14483 13633 13601 13906 500 5 11489 11644 10992 11375 341 Sodium 10 12097 12854 13252 12734 587 Pentaborate 15 11139 11757 12106 11667 490 5 15135 16313 16702 16050 816 Disodium 10 17264 17845 16408 17172 723 Octaborate 15 16266 16134 13354 15251 1644

(42) TABLE-US-00003 TABLE 3 Tensile strengths of pectin based film surfaces Ratio Tensile Strength (g) Active (%) 1 2 3 Average (g) Std. - (Control) 849 1109 932 963 133 5 1623 1649 1853 1708 126 Boric Acid 10 1672 1712 1825 1736 79 15 1603 1601 1588 1597 8 5 1452 1403 1514 1456 56 Sodium 10 1755 2229 2363 2116 319 Pentaborate 15 2044 2118 2349 2170 159 5 1066 1130 1015 1070 58 Disodium 10 1970 2082 1883 1978 100 Octaborate 15 1533 1395 1369 1432 88

(43) As the molecular sequence converges, film surfaces tend to get thinner. Thus, addition of boron influences thickness of the gelatin or pectin based film surfaces. Interaction of boron with RG-II, which is inherent in pectin, causes the film to be thinner. Therefore boron containing films are thinner than the control groups. Since different boron compounds influence cross-links of biopolymers at different extents, a different thickness is obtained at each sample. Addition of boron compounds does not have an important influence on the thicknesses of the gelatin films. Table 4 and Table 5 show thicknesses of the boron compound-doped gelatin and pectin based film samples.

(44) TABLE-US-00004 TABLE 4 Thicknesses of the gelatin based films containing boron compounds Ratio Thickness Average Active (%) (mm) (mm) Std. - (Control) 0 0.26 0.25 0.26 0.01 Boric Acid 5 0.22 0.25 0.24 0.02 10 0.29 0.28 0.29 0.01 15 0.27 0.29 0.28 0.01 Sodium 5 0.25 0.26 0.26 0.01 Pentaborate 10 0.26 0.24 0.25 0.01 15 0.26 0.26 0.26 0.00 Disodium 5 0.25 0.26 0.26 0.01 Octaborate 10 0.28 0.28 0.28 0.00 15 0.28 0.28 0.28 0.00

(45) TABLE-US-00005 TABLE 5 Thicknesses of the pectin based films containing boron compounds Ratio Thickness Average Active (%) (mm) (mm) Std. - (Control) 0 0.2 0.21 0.21 0.01 Boric Acid 5 0.14 0.13 0.14 0.01 10 0.16 0.15 0.16 0.01 15 0.14 0.13 0.14 0.01 Sodium 5 0.18 0.18 0.18 0.00 Pentaborate 10 0.15 0.15 0.15 0.00 15 0.16 0.15 0.16 0.01 Disodium 5 0.18 0.17 0.18 0.01 Octaborate 10 0.18 0.18 0.18 0.00 15 0.16 0.15 0.16 0.01

(46) Determining the Rheological Properties

(47) Since gelatin has a thermoreversible gelling mechanism, the effects of boron compounds on gelling and melting temperatures are investigated by rheological tests. It is observed that boron compounds do not significantly change gelling and melting temperatures or deform gel structure. Changes in melting (T.sub.m) and gelling (T.sub.g) temperatures of the gelatin gels are given in Table 6.

(48) Viscosity graphics of the pectin or gelatin based gel solutions containing 3 different boron derivatives of different concentrations according to the changing shear rates are given in FIG. 17 and FIG. 18. All of the gelatin and pectin samples have exhibited shear thinning behavior. While the pectin sample containing 15% (w/w) boric acid has the lowest viscosity value, the pectin sample containing 10% (w/w) disodium octaborate has the highest viscosity value. In gelatin based films, disodium octaborate-added gelatin solutions have the highest viscosity value. Addition of boric acid has caused a decrease in the viscosity of the gelatin.

(49) TABLE-US-00006 TABLE 6 Melting (T.sub.m) and Gelling (T.sub.g) Temperatures of Gelatin Gels Doped with Boron Derivatives Ratio Control Boric Acid Disodium Octaborate Sodium Pentaborate (%) 0 5 10 15 5 10 15 5 10 15 T, 22.7° C. 22.3° C. 22.2° C. 21.4° C. 22.3° C. 21.8° C. 21.4° C. 22.3° C. 21.9° C. 21.4° C. T.sub.m 30.9° C. 30.7° C. 30.5° C. 30.4° C. 30.9° C. 31.1° C. 30.5° C. 31.1° C. 30.5° C. 30.5° C.

INDUSTRIAL APPLICATIONS

(50) The present invention relates to a gelatin or pectin based antimicrobial surface coating material. The surface coating material is obtained in the form of a film, and used as a packaging material in industrial application. The said packages to be used as coating materials can be used in all fields requiring hygiene particularly in food industry. In food packaging, the surfaces contacting the food and external environment or consumer are antibacterial, antifungal and anticandidal such that they will not be harmful to human health. By means of the present invention, a coating material is developed, which is effective against all kinds of pathogenic factors (bacteria, fungi and viruses) that are present both on the surfaces of and inside the food packages, and which does not harm human health or food quality.

(51) The surface coating material of the present invention is also used in drug and cosmetic industries in addition to food industry. Use thereof as a coating material in pills or tablets in drug industry is another field of use which is alternative to its use on fruits or similar food products.

(52) The said surface coating material can be in the form of a solid powder or liquid solution. It can be applied on fruits and vegetables as a solution via spraying or immersion method.

REFERENCES

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