Disclosure of Invention
In order to solve the technical problems, the invention aims to provide a preparation method of a colorimetric array for monitoring the freshness change in refrigerated fish transportation, and the freshness indicating colorimetric array obtained by the method has the color changing along with the freshness of fish, so that the freshness of foods in packages can be rapidly and accurately indicated.
In order to achieve the above purpose, the present invention provides the following technical scheme: comprises the steps of,
Dissolving carboxymethyl cellulose (1.0 g/100ml-2.0/100ml based on deionized water) powder in deionized water at 85-95deg.C, stirring for 50-60min, and adding glycerol to obtain carboxymethyl fiber solution; dissolving natural pigment to obtain an indicator dye; cooling the carboxymethyl cellulose solution to 35-45 ℃, adding an indicator dye into the carboxymethyl cellulose solution to obtain a film forming liquid, and pouring the film forming liquid into a polystyrene culture dish after degassing to obtain a completely gelled indicator film;
dissolving starch in deionized water at 90-100deg.C, stirring for 25-35min, and adding glycerol; adding myogenin into the starch solution, and then performing ultrasonic treatment by an ultrasonic processor to obtain film forming liquid;
And (3) degassing the film forming liquid, pouring the film forming liquid onto a completely gelled indicator film, and drying to obtain the freshness indicating colorimetric array based on the natural pigment.
Preferably, the natural pigment is anthocyanin, curcumin and betalain mixture or anthocyanin or curcumin or betalain, and the concentration of the indicator solution of the indicator dye is 40-60mg/ml.
Preferably, when the natural pigment is a mixture of anthocyanin, curcumin and betalain, the mass ratio of anthocyanin, curcumin and betalain is 1:1:1.
Preferably, the drying conditions are drying at 45 ℃ for 24 hours.
Preferably, the specific weight proportion relation of the raw materials in the colorimetric array is as follows: carboxymethyl cellulose, natural pigment, starch, myogenin = 6:0.16:2:1, wherein the concentration of myogenin is 2% -6%.
Preferably, the carboxymethyl cellulose powder is dissolved in deionized water at 85-95 ℃ and sufficiently stirred for 50-60min, and the cooling temperature of the carboxymethyl cellulose solution is 35-45 ℃.
Preferably, the starch is dissolved in deionized water at 90-100 ℃ and stirred for 25-35min.
The invention also comprises application of the fish freshness indicating colorimetric array, wherein the fish freshness indicating colorimetric array prepared by the preparation method based on the natural pigment is applied to indicating fish freshness.
The invention has the beneficial effects that: firstly, the colorimetric array contains myogenic protein to improve the gas adsorption capacity of the indicator layer; secondly, the colorimetric array can be used for realizing real-time, nondestructive and convenient detection of the freshness of meat; the pigments are anthocyanin, curcumin and beet red, are natural plant extracts, and the polymers for preparing the colorimetric array are food-grade and are safe and edible.
Detailed Description
The following detailed description of embodiments of the invention is, therefore, to be taken in conjunction with the accompanying drawings, and it is to be understood that the scope of the invention is not limited to the specific embodiments. It should be noted that the experimental methods used in the following examples are all conventional methods unless otherwise specified; materials, reagents and the like used in the examples described below are commercially available unless otherwise specified.
The specific conditions are not noted in the examples and are carried out according to conventional conditions or conditions recommended by the manufacturer. The reagents or apparatus used were conventional products commercially available without the manufacturer's attention. In order to make the objects, technical solutions and advantages of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below.
Example 1
In recent years, the water-borne food has a great effect as a nutrition source in maintaining human health, and the demand is increased year by year. The freshness of fish meat is generally defined as whether or not a physical or chemical change has been made to fresh fish and the degree of the change. Fresh fish aquatic products are easy to spoil in the storage and transportation process, so that certain economic loss is caused, and along with the improvement of the living standard of people, the requirements on the freshness of the fresh fish aquatic products are higher and higher, and the research of a comprehensive evaluation system for the freshness of the fish aquatic products is enhanced, so that the method has important social and economic benefits.
The embodiment provides a preparation method of a fish flesh freshness indication colorimetric array based on natural pigment, which comprises the following specific actual preparation processes:
Selecting raw materials: anthocyanin (ATH), curcumin (CUR), betalain (BET), carboxymethyl cellulose (CMC), starch (S), myogenin (MP), glycerol.
The preparation method of the colorimetric array comprises the following steps:
(1) CMC-ATH-CUR indicated film preparation.
6G of carboxymethylcellulose (CMC) powder was dissolved in 500mL of deionized water at 90℃and stirred well for 60min. Glycerol (30% of dry matter (carboxymethyl cellulose powder)) was added as a plasticizer to give a carboxymethyl cellulose solution. 0.16g of anthocyanin-curcumin (ATH-CUR, 1:1) was dissolved in 47.5% ethanol to give an indicator solution. When the carboxymethyl cellulose solution was cooled to 40 ℃, an indicator solution was added thereto to obtain a film-forming solution containing 40mg/mL of natural pigment. After degassing, 40mL of the film-forming solution was poured into polystyrene petri dishes with a diameter of 10cm, giving a fully gelled indicator film, designated CMC-ATH-CUR.
(2) Preparation of CMC-ATH-BET indicator film.
6G of carboxymethylcellulose (CMC) powder was dissolved in 500mL of deionized water at 90℃and stirred well for 60min. Glycerol (30% of dry matter (carboxymethyl cellulose powder)) was added as a plasticizer to give a carboxymethyl cellulose solution. 0.16g of anthocyanin-betalain (ATH-BET, 1:1) was dissolved in 40ml of deionized water to give an indicator solution. When the carboxymethyl cellulose solution was cooled to 40 ℃, an indicator solution was added thereto to obtain a film-forming solution containing 40mg/mL of natural pigment. After degassing, 40mL of the film-forming solution was poured into polystyrene petri dishes of 10cm diameter, giving a fully gelled indicator film, designated CMC-ATH-BET.
(3) Preparation of CMC-CUR-BET indicator film.
6G of carboxymethylcellulose (CMC) powder was dissolved in 500mL of deionized water at 90℃and stirred well for 60min. Glycerol (30% of dry matter (carboxymethyl cellulose powder)) was added as a plasticizer to give a carboxymethyl cellulose solution. 0.16g of curcumin-betalain (CUR-BET, 1:1) was dissolved in 47.5% ethanol to give an indicator solution. When the carboxymethyl cellulose solution was cooled to 40 ℃, an indicator solution was added thereto to obtain a film-forming solution containing 40mg/mL of natural pigment. After degassing, 40mL of the film-forming solution was poured into polystyrene petri dishes of 10cm diameter, giving a fully gelled indicator film, designated CMC-CUR-BET.
(4) CMC-ATH indicates the preparation of the film.
6G of carboxymethylcellulose (CMC) powder was dissolved in 500mL of deionized water at 90℃and stirred well for 60min. Glycerol (30% of dry matter (carboxymethyl cellulose powder)) was added as a plasticizer to give a carboxymethyl cellulose solution. 0.16g of Anthocyanin (ATH) was dissolved in 40mL of deionized water to give an indicator solution. When the carboxymethyl cellulose solution was cooled to 40 ℃, an indicator solution was added thereto to obtain a film-forming solution containing 40mg/mL of natural pigment. After degassing, 40mL of the film-forming solution was poured into polystyrene petri dishes of 10cm diameter, giving a fully gelled indicator film, designated CMC-ATH.
(5) CMC-CUR indicates preparation of the film.
6G of carboxymethylcellulose (CMC) powder was dissolved in 500mL of deionized water at 90℃and stirred well for 60min. Glycerol (30% of dry matter (carboxymethyl cellulose powder)) was added as a plasticizer to give a carboxymethyl cellulose solution. 0.16g Curcumin (CUR) was dissolved in 95% ethanol to obtain an indicator solution. When the carboxymethyl cellulose solution was cooled to 40 ℃, an indicator solution was added thereto to obtain a film-forming solution containing 40mg/mL of natural pigment. After degassing, 40mL of the film-forming solution was poured into polystyrene petri dishes with a diameter of 10cm, giving a fully gelled indicator film, designated CMC-CUR.
(6) Preparation of CMC-BET indicator film.
6G of carboxymethylcellulose (CMC) powder was dissolved in 500mL of deionized water at 90℃and stirred well for 60min. Glycerol (30% of dry matter (carboxymethyl cellulose powder)) was added as a plasticizer to give a carboxymethyl cellulose solution. 0.16g Betalain (BET) was dissolved in 40mL deionized water to provide an indicator solution. When the carboxymethyl cellulose solution was cooled to 40 ℃, an indicator solution was added thereto to obtain a film-forming solution containing 40mg/mL of natural pigment. After degassing, 40mL of the film-forming solution was poured into polystyrene petri dishes of 10cm diameter, giving a fully gelled indicator film, designated CMC-BET.
(7) And (5) preparing a film forming liquid.
Dissolving starch in deionized water at 90-100deg.C, stirring for 25-35min, and adding glycerol; myogenic protein is added into starch solution, and then film forming liquid is obtained by ultrasonic treatment through an ultrasonic processor.
(8) Colorimetric array preparation.
After degassing the film-forming emulsion, pouring onto a fully gelled indicator film (CMC-ATH-CUR, CMC-ATH-BET, CMC-CUR-BET, CMC-ATH, CMC-CUR, CMC-BET), and drying the resulting film at 45℃for 24 hours to give a colorimetric array. Referring to the schematic of fig. 1, there is illustrated a structural exploded view of the fish freshness indicating colorimetric array of the present embodiment, wherein reference numerals are:
1-CMC-ATH-CUR indication film, 2-CMC-ATH-BET indication film, 3-CMC-CUR-BET indication film, 4-CMC-ATH indication film, 5-CMC-CUR indication film, 6-CMC-BET indication film, and 7-starch adsorption gas layer containing myogenin.
Example 2
According to the colorimetric array for indicating the freshness of the fish meat, which is provided by the embodiment, the colorimetric array is stuck in a package, and the freshness is detected in real time according to the color change of the colorimetric array, so that the freshness of the fish meat can be identified.
The colorimetric array was prepared as in example 1.
Adding 90mL of 8mol/L ammonia water into a 100mL beaker, fixing a colorimetric array (8 cm multiplied by 5 cm) in a culture medium, reversely buckling the culture medium into a bottle mouth, collecting image information of a label at room temperature once every 3min for 21min, extracting RGB values of the label by using a Photoshop2018 color sampler, and calculating the sensitivity of the label according to the following calculation formula:
wherein R0、G0、B0 is a value of 0min.
The results are shown in FIG. 2, where the sensitivity of the colorimetric array varies with increasing ammonia reaction time, with the sensitivity of the composite indicator being higher than that of the single indicator.
The fresh cod sample was placed in a clear plastic display box and then wrapped with a sterilized polyester/polypropylene film, and the indicating colorimetric array was directly overlaid on top of the box. As shown in fig. 3, the samples were stored at 25 ℃ for 12 hours and the color change of the colorimetric array was observed, wherein:
The color of the CMC-ATH-CURpH sensitizer coating changes from earthy yellow to dark green according to the freshness of the cod;
The color of the CMC-ATH-BET pH sensitizer coating changed from purple to deep blue depending on the freshness of the cod;
the color of the CMC-CUR-BET pH sensitizer coating changes from orange red to light green according to the freshness of the cod;
The color of the CMC-ATH pH sensitive agent coating changes from light purple to blue-green according to the freshness of the codfish;
The color of the CMC-CURpH sensitizer coating changes from yellow to bright red according to the freshness of the cod;
The color of the CMC-BET pH-sensitive agent coating changed from pink to pale yellow depending on the freshness of the cod.
In fig. 3, the color change of the colorimetric array is obvious, and the freshness of the codfish can be intuitively judged.
It should be understood that the present invention has been described in terms of embodiments, and that the embodiments are only capable of implementing the clear and complete description of the technical solutions set forth in the claims of the present invention, i.e., the explanation of the claims, so that when judging whether the technical solutions set forth in the present invention are sufficiently disclosed, the gist of the solutions defined in the claims should be fully considered, and other technical problems unrelated to the technical solutions set forth in the embodiments are necessarily present in the description, and the corresponding technical features and technical solutions are not necessarily indicated by the gist of the embodiments, so that the technical solutions can be implemented by fully combining the prior art with the common knowledge in the art with reference to implicit disclosure, and thus are not necessary to be described in detail.
It should be noted that the above embodiments are only for illustrating the technical solution of the present invention and not for limiting the same, and although the present invention has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that the technical solution of the present invention may be modified or substituted without departing from the spirit and scope of the technical solution of the present invention, which is intended to be covered in the scope of the claims of the present invention.