TR2023016104A2 - DEVELOPMENT OF SMART PACKAGING INCLUDING A COLOR-CHANGING INDICATOR TO MONITOR FRESHNESS/POISONATION OF PERISHABLE FOODS IN REAL TIME - Google Patents

Abstract

The invention relates to a color-changing smart indicator (A) to be used in packaging in the food industry.

Description

DESCRIPTION DEVELOPMENT OF SMART PACKAGING CONTAINING A COLOR-CHANGING INDICATOR TO MONITOR FRESHNESS/POISONING IN REAL TIME IN PERISHABLE FOODS Technical Area The invention is related to a smart indicator that changes color for use in packaging in the food industry. State of the Art Freshness indicators, a type of smart indicator, are visual tools that work on the principle of changing color in the presence of metabolites that occur as a result of microbial spoilage or chemical changes in foods. The quality of food is determined by traditional analysis methods, which are time-consuming, expensive and destructive. The biggest advantages of freshness indicators are; The quality, freshness and safety of packaged foods can be determined non-destructively in real time with the naked eye, thanks to the "color change" (Rukchon et al., 2014; Morsy et al., 2016; Lee et al., 2019; Öksüztepe and Beyazgül, 2015). Thanks to these developed visual tools, food safety can be ensured by detecting products that spoil before their expiration date or that continue to be sold even after their expiration date. It has a great potential not only to ensure food security, but also to prevent 1.3 billion tons of food waste that goes to waste every year, according to FAO (2020) data (Racionero et al., 2017). In freshness indicator studies in the literature, many synthetic pH dyes such as bromothymol blue, methyl red, bromocresol green and bromocresol purple, as well as different plants such as curcumin, alizarin, chlorophyll, purple carrot, hibiscus (roselle) are used to observe the color change indicating spoilage of the food. extracted natural color pigments (Bhandari and Yang, 2019). Although natural dyes have features such as low toxicity, biodegradability, and wide color range, they are not sufficient for freshness indicator applications due to poor color stabilization. In this context, synthetic pH dyes provide greater opportunity for the production of indicators that are sensitive to different degradation metabolites of acidic or basic types, as they offer high color stabilization and a wide color change range (Bao et al., 2022; Shao et al., 2021). For the design of an industrially adaptable indicator, the materials to be used as the inner and outer layers are expected to be resistant to environmental factors such as humidity, temperature, light, UV and to protect the color change layer containing dye against migration. However, in some of the studies in the literature, hydrophilic filter paper was used as the inner layer and in some as the background. The layers are held together with tape aid instead of the lamination process et al., 2019; Ezati et al., 2019). Due to its structure and properties, filter paper is not resistant to any environmental conditions and is not capable of ensuring food safety and being applied to the industry. The majority of food validation studies of smart labels/indicators in the literature have been carried out in petri dishes and air atmosphere, and are far from real packaging practice. Additionally, simulation studies and food packaging applications (material and atmosphere) do not represent real packaging conditions (Chi et al., 2020; Franco, Cunha, & Bianch, 2021; Yildiz, Sumnu, & Kahyaoglu, 2021). In existing studies, the color transition is predominantly between two colors and only expresses freshness and/or spoilage. Although there are many patented TTI (Temperature Time Indicators), these are sensitive to the temperature of the environment in which the food is located, and color change only occurs due to temperature fluctuations/changes. Therefore, it only follows the cold chain and indirectly provides information about food quality and/or freshness. The freshness indicator we developed reacts with the spoilage metabolite in the packaging environment and provides direct information about the spoilage/freshness of the food. As a result, due to the negativities described above and the inadequacy of existing solutions on the subject, it has been deemed necessary to make a development in the relevant technical field. Brief Description of the Invention The present invention is related to a smart indicator that meets the above-mentioned requirements, eliminates all disadvantages and brings some additional advantages. The invention is inspired by current situations and aims to solve the above-mentioned drawbacks. The smart indicator/freshness indicator that is the subject of the invention can be used in the fields of food packaging, food safety, food quality control and smart packaging. The indicator in question will indicate in real time that the food is spoiled, with the color changing feature of the three-layer smart indicator, which is sensitive to the spoilage metabolite (C02) formed when the packaged food (chicken) spoils and contains bromothymol blue (BTB) dye. Thanks to smart packaging technology, the changes that food undergoes during transportation, storage, sale and use can be monitored by producers, sellers and consumers. It is a system that can be generally used by the food and packaging industry. In the invention, a 3-layer smart indicator has been developed; pH-sensitive BTB dye was bonded to a methyl cellulose matrix and placed between two plastic layers commonly used in the food packaging industry. The upper layer, the transparent PET film, allows the color change to be monitored, and the lower layer, the white colored LDPE film, allows gas permeability (CO, which is the degradation metabolite) and also provides a white background for the color change layer to better distinguish the color. In previous studies, the use of a white background due to the structure of the indicator was not encountered. It is aimed to use the BTB-based and three-layer smart indicator sensitive to the CO2 degradation metabolite in packaged chicken. BTB-based indicators developed with the invention were tested using real packaging conditions in simulation and food validation studies. For this purpose, commercial PA/PE packaging bags were used and tests were carried out in air and 100% N2 atmospheres. BTB-based freshness indicators provided a three-stage color transition (bright blue-turquoise-green) during the cold storage process, and the concentration at which the C02 metabolite represents the degradation range (10-15% (v/v)) was also associated with microbiological and sensory results. This color change provides the advantage of visually presenting the freshness of chicken meat to the consumer in three different ways: "fresh (blue), still fresh but should be consumed immediately (turquoise) and spoiled (green)". The freshness indicator we developed reacts with the spoilage metabolite in the packaging environment and provides direct information about the spoilage/freshness of the food. The color change develops in direct proportion to the amount of CO2, which is the degradation metabolite. The structural and characteristic features and all the advantages of the invention will be more clearly understood thanks to the figures given below and the detailed explanation written by making references to these figures, and therefore the evaluation should be made taking these figures and detailed explanation into consideration. Figures to Help Understand the Invention In order to best understand the structure and advantages of the current invention, it should be evaluated together with the figures explained below. Figure 1 shows the general view of the smart indicator. Part References A Intelligent indicator 1 Outer layer 2 Color change layer 3 Adhesive layer 4 Inner layer Detailed Description of the Invention In this detailed description, preferred embodiments of the invention are explained only for a better understanding of the subject. The invention relates to the intelligent indicator (A) to be used in packaging in the food industry. In the intelligent indicator (A) structure of the invention, there is at least one outer layer (1) in the outermost part. The outer layer in question, preferably in the form of a transparent PET film, is 13 µm thick. The transparent PET film in question allows the color change to be monitored. The color change layer (2) is sensitive to the C02 metabolite. The color change layer (2) in question contains dye solution, binder solution and doping solution. Preferred contents and preferred amounts by weight of the mentioned ingredients are given below: Preferred Component Amount by Weight Dye squeezing BromothymoI blue (BTB) Methyl cellulose (MS) 2.86 (w/v) Polyethylene glycol Binding (PEG)-4OO solution Water 95, 24 (v/v) - 2 M Sodium DOp'ng SO ion hydroxide (NaOH) 095 MW In the invention, the total amounts of 50% Ethyl alcohol, water and Sodium hydroxide (NaOH) by volume reach 99.99%. The remaining volume is completed by weight of Bromothymol blue (BTB), Methyl cellulose (MS) and Polyethylene glycol (PEG)-4OO. In the invention, smart indicator (A); It contains at least one inner layer (4). Inner layer (4); It is white colored LDPE and 50 um thick. White color LDPE film; It allows gas permeability (COg, which is the degradation metabolite) to be ensured and also to create a white background for the color change layer (2) for better color discrimination. At least one adhesive layer (3) is used to laminate the outer layer (1) and the inner layer (4). Adhesive layer (3) in glue form; It is obtained from organic components and must have high chemical resistance and be suitable for lamination with polymer materials. In the method of the invention, firstly, the dye solution is prepared. For this purpose, 50% Ethyl alcohol and Bromothymol blue (BTB) are used. Then, the binder solution is prepared. As mentioned above, this solution contains Methyl cellulose (MS), Polyethylene glycol (PEG)-4OO and water. In the next process step, the prepared dye solution is transferred to the binder solution. Doping solution is added to the resulting solution. The mixture of dye solution, binder solution and doping solution is transferred to the outer layer (1) surface of the smart indicator and the dye layer is obtained. After the drying process, lamination is done with white LDPE film and the curing process is carried out. Indicators, preferably prepared in 4x4 cm2 size, are made ready for food application. The developed color changeable indicator is transferred to the coronal surface of the outer layer (1). The indicator transferred surface of the PET film (outer layer (1)) is laminated with white Polyethylene film. The smart indicators developed in the invention were validated as sensitive only to C02, one of the metabolites formed by spoilage in chicken meat, and under the given packaging conditions. A similar indicator can be developed with different pH dyes, but the sensitivity of the indicator to the spoilage metabolite determined in the targeted food and the color change mechanism must be tested. Likewise, this invention may vary depending on the type of dye used in the indicator, the initial pH level, the technical and optical properties of the films on the lower and upper layers of the dye layer, the food it is tested on, the storage temperature of the food, the selected packaging materials and atmosphere. Although a white background is used in state-of-the-art applications, this white background is provided with filter paper. However, in the smart indicator that is the subject of the invention, the white color is the color of LDPEl, which is a commercial material. The functions provided by the components used in the invention are summarized below: Ethyl alcohol-It was used to dissolve the BTB dye used in the color layer of the smart indicator. BTB (bromothymol blue) was used as the dye source that provides the color change in the indicator. Methyl cellulose (MS) was used as a binding matrix to prevent the leakage (migration) of the dye by increasing the viscosity of the dye solution. Since it is water-based, it can be dissolved in water without the need to use solvents. It was used to increase the flexibility of the PEG- layer. NaOH- It was used as doping to adjust the initial pH value of the indicator (dye) solution. The initial content of the dye solution was increased and used to better monitor/visualize the color change when it reacted with acidic CO2. NaOH increased the pH value of the indicator solutions, making the initial color of the indicator more prominent. The development of smart indicators and their structural and functional properties for a preferred application of the invention are explained below: Dye solution was prepared at 1% (w/v) concentration by dissolving it in 2 ml of ethanol on a magnetic stirrer at 500 rpm for 30 minutes. For the binder solution, 1.5 9 methyl cellulose was prepared by dissolving it in 50 ml of distilled water (3% w/v) on a magnetic stirrer at 500 rpm for 30 minutes. In order to give elasticity to the structure, it was added to the binder solution and mixed at 500 rpm in a magnetic stirrer. To prepare the indicator solution containing BTB dye, 2 ml of the dye solution was added to the methyl cellulose-based binder solution and mixed for 15 minutes on a magnetic stirrer to ensure a homogeneous distribution of the dye. In order to adjust the initial pH value of the indicator solutions, 2 ml NaOHltan was used as doping and homogenized at 5000 rpm for 15 minutes. 1 ml of the obtained indicator solutions was taken and spread in 2 cm diameter circles on the PET film (on the surface of which corona treatment was applied to ensure that the solutions adhere well) and the solutions were dried in an oven (Ecocell) at 40 °C overnight. The dried films were subjected to the lamination process in order to prevent dye migration. The lamination process was carried out by applying a mixture of glue and catalyst between the color change layer on the PET surface and the white LDPE film (50 um was chosen as white to ensure better perception of the color change). In this way, the curing process was carried out, which ensured that the laminated indicators adhered to each other. The PET film containing the color change layer and the LDPE film, which is the inner layer, are sealed to each other. Freshness indicators are preferably prepared in 4x4 cm2 dimensions. The freshness indicator production flow chart is shown in Figure 1. All explanations regarding the indicator size in this text are only available. It is presented for informational purposes only and does not contain any restrictive meaning. Although the indicator is prepared in this size, the final application is not limited to this size. Its size may change in different applications, for example, in accordance with the industrial production purpose. After the developed color changeable indicator is turned into dye in industrial processes, it is partially transferred to the side of the PET film with appropriate surface tension (corona) as reverse printing in rotogravure or flexo printing machine systems. The indicator transferred surface of the PET film is laminated with white Polyethylene film (HDPE, LDPE, MDPE, LLDPE) with the help of glue (the glue can be with or without solvent) in a laminating machine with or without solvent. In a preferred embodiment of the invention, the parameter ranges are given below: Drying of the paint layer on the PET surface can be carried out at 40-42 °C. The transparent polyethylene terephthalate (PET) film used as the outer layer (1) can be used with a thickness of 13-15 um, and the white low-density polyethylene (LDPE) used as the inner layer can be used with a thickness of 40-50 um. However, the main criterion is that the metabolite (CO2) permeability (COgTR of 17612 cms/mgsunatm) of the inner layer at the stage of food spoilage is sufficient for color change. The storage temperature of packaged chicken meat to which smart indicators are applied should be between +4 and +4.5 °C. There are some points that need to be taken into consideration in the application of the smart indicators that are the subject of the invention. The developed smart indicator has been tested to determine spoilage in chicken meat and is only valid for the packaging and storage conditions given above. The change of packaging material, atmosphere and storage temperature affect the food spoilage mechanism, so the smart indicator only has the color changing mechanism described under the given specific conditions. The C02 rate formed when chicken breast meat was stored under two different atmospheres at 4°C for 10 days increased during storage, and the freshness indicator showed both visible and measurable color changes at the C02 degradation range values (10-15% C02) reported in the literature. The three-stage (bright blue-turquoise-green) color changes observed in BTB-based freshness indicators during storage were associated with the degradation range of the C02 metabolite (10-15% (v/v)), microbiological and sensory consequences. This color change provides the advantage of visually presenting the freshness of chicken meat to the consumer in three different ways: "fresh, still fresh but should be consumed immediately and spoiled". The developed colorimetric freshness indicator not only provides information about the freshness of the food, but also has great importance for the food packaging industry in terms of issues such as food safety, waste reduction, traceability and sustainability. The color change processes of the developed indicator during storage may vary with the initial microbial load of the packaged food. In the studies carried out within the scope of the invention, the effectiveness of the colorimetric freshness indicator, which has the sensitivity to detect the C02 metabolite produced by microorganisms as a result of spoilage in chicken meat, was tested in a food validation study. 0 Fresh boneless chicken breast samples, obtained from a local market and with a pH value of 5.9-6.5, were cut into 200 g portions under sterile conditions and then placed in PA/PE packages (18 x 20 cm2) containing BTB-based colorimetric freshness indicators. It is packaged with a MAP machine (Reepack, Italy) underneath. 0 All packages containing chicken breast were stored at +4±0.5°C for 10 days, and on days 0, 2, 4, 6, 8 and 10, headspace gas composition (%C02 and 02), pH, TVB-N Color analyzes were carried out on sensory evaluation and freshness indicators, trimethylamine (TMA), total mesophilic bacteria and Pseudomonas aeruginosa. 0 The color change of freshness indicators on each analysis day (days 0, 2, 4, 6, 8, 10) was determined by delta E and delta RGB.TR TR TR

Claims (1)

1.STEMS. It is a smart indicator (A) to be used in packaging in the food industry, and its features are; o at least one external color change layer (2) in transparent form, containing dye solution, binding solution and doping solution and sensitive to CO2 metabolite, to enable monitoring of color change on the outer part, o suitable for the purpose of ensuring gas permeability and detecting color change It contains at least one inner layer (4), which is white in color, and at least one adhesive layer (3) to laminate the outer layer (1) and the inner layer (4). It is a smart indicator (A) in accordance with claim 1, and its feature is; The outer layer (1) in question is in the form of a transparent PET film. It is a smart indicator (A) in accordance with claim 1, and its feature is; The outer layer (1) in question is 13 um thick. It is a smart indicator (A) in accordance with claim 1, and its feature is; said inner layer (4); It is white colored LDPE. It is a smart indicator (A) in accordance with claim 1, and its feature is; said inner layer (4); It is 50 um thick. It is a smart indicator (A) in accordance with claim 1, and its feature is; The dye solution contains 0/<›50% Ethyl alcohol and Bromothymol blue (BTB). It is a smart indicator (A) in accordance with claim 1, and its feature is; The binding solution contains Methyl cellulose (MS), Polyethylene incoI (PEG)-400 and water. It is a smart indicator (A) in accordance with claim 1, and its feature is; The doping solution contains Sodium hydroxide (NaOH). TR TR TR