Pineapple-flavor instant film and preparation method thereof

Abstract

The invention belongs to the technical field of instant films, and particularly relates to a pineapple-flavor instant film and a preparation method thereof. The pineapple-flavor instant film comprises the following components in percentage by weight: 35-40% of D-mannitol, 20-25% of lactic acid bacteria composite powder, 5-10% of pullulan, 3-8% of lactic acid bacteria powder, 3-7% of pineapple powder, 4-9% of modified hydroxypropyl methyl cellulose, 2-5% of glycerol, 2-5% of pineapple essence, 1-3% of modified xanthan gum and the balance of water. The pineapple-flavor instant film has the advantages of being environmentally friendly, high in mechanical property, good in barrier property and the like.

Description

Technical Field

[0001] The present invention belongs to the technical field of instant films, and particularly relates to a pineapple - flavored instant film and a preparation method thereof. Background Art

[0002] An edible instant film is an innovative packaging material that can not only dissolve rapidly in water but is also safe and edible. Such films are usually made from natural polymer materials such as starch, protein, polysaccharides (such as agar, chitosan), cellulose derivatives, etc., or pigments and flavors to enhance the sensory experience.

[0003] Traditional edible films mostly use a single film - forming matrix (such as starch, sodium alginate or polyvinyl alcohol). Although they have certain film - forming properties, they have the problem of insufficient mechanical strength. Summary of the Invention

[0004] The purpose of the present invention is to provide a pineapple - flavored instant film and a preparation method thereof.

[0005] To achieve the above purpose, the present invention provides the following technical solutions:

[0006] A pineapple - flavored instant film, comprising the following components in weight percentages: D - mannitol 35 - 40%, lactic acid bacteria complex powder 20 - 25%, pullulan polysaccharide 5 - 10%, lactic acid bacteria powder 3 - 8%, pineapple powder 3 - 7%, modified hydroxypropyl methylcellulose 4 - 9%, glycerol 2 - 5%, pineapple essence 2 - 5%, modified xanthan gum 1 - 3%, and the balance is water.

[0007] Further, the preparation method of the modified hydroxypropyl methylcellulose comprises the following steps:

[0008] (1) Dissolve complex enzyme A in water at 35 - 40°C and let it stand for activation;

[0009] (2) Disperse hydroxypropyl methylcellulose in water at 45 - 50°C and stir until completely swollen to obtain an HPMC solution;

[0010] (3) Add the activated enzyme solution to the HPMC solution, stir and react at a constant temperature of 45 - 50°C for 2 - 3 hours, inactivate the enzyme activity, cool, and then spray - dry to obtain the modified hydroxypropyl methylcellulose.

[0011] Further, the complex enzyme A comprises xylanase and transglutaminase in a weight ratio of 1:(2 - 3).

[0012] Further, the concentration of the complex enzyme A in water is 0.5 - 1.0 wt%.

[0013] Further, the concentration of hydroxypropyl methylcellulose in water is 3 - 5 wt%.

[0014] Further, the preparation method of the modified xanthan gum comprises the following steps:

[0015] (1) Dissolve composite enzyme B in an acetate buffer solution, add xanthan gum and carboxymethyl cellulose, and premix; react at 50 - 55 °C in an oxygen atmosphere for 4 - 6 hours, inactivate the enzyme, and dialyze to remove unreacted monomers with a cut-off molecular weight of 10 kDa to generate a xanthan gum-CMC graft copolymer;

[0016] (2) Dissolve whey protein in water, heat to induce denaturation to form a pre-gel, mix the xanthan gum-CMC graft copolymer with the pre-gel, stir at 50 - 55 °C for 1 - 2 hours, add lactic acid dropwise to adjust the pH, let stand for 2 - 3 hours to complete gelation, dry, and pulverize to obtain the modified xanthan gum.

[0017] Further, composite enzyme B comprises pectinase and laccase with a weight ratio of 1:(2 - 3).

[0018] Further, the concentration of composite enzyme B in the acetate buffer solution is 0.5 - 0.7 wt%.

[0019] Further, the concentration of xanthan gum in the acetate buffer solution is 3 - 3.5 wt%; the concentration of carboxymethyl cellulose in the acetate buffer solution is 1 - 2 wt%.

[0020] The preparation method of a pineapple-flavored instant film, characterized by comprising the following steps:

[0021] (1) Pre-swelling of the film-forming matrix: Heat water to 50 - 60 °C, add modified hydroxypropyl methylcellulose, pullulan polysaccharide, and modified xanthan gum, shear and disperse to form a uniform glue solution; sequentially add glycerol and D-mannitol to the glue solution, and stir in a constant-temperature water bath until completely dissolved;

[0022] (2) Gradient addition of functional components: Cool the glue solution to 25 - 30 °C, sequentially add the lactic acid bacteria composite powder and lactic acid bacteria powder, and stir with a low-speed paddle; add pineapple powder and pineapple essence, and homogenize with a vacuum homogenizer;

[0023] (3) Defoaming and coating and forming: Transfer the mixed slurry to a vacuum defoaming tank for vacuum defoaming, coat with a slot coater, and select an acrylic plate as the substrate to ensure that the water content of the film is ≤5%;

[0024] (4) Take the dried film off the acrylic plate at room temperature to obtain the pineapple-flavored instant film.

[0025] Compared with the prior art, the advantages and beneficial effects of the present invention are:

[0026] 1. The pineapple - flavored instant film of the present invention not only inherits the basic characteristics of traditional edible instant films, such as environmental protection and safety, but also particularly adds pineapple flavor elements, endowing it with a unique aroma and taste, making it more popular in practical applications. This new - type instant film is green and environmentally friendly. Through careful selection and proportioning, it ensures good mechanical properties and barrier properties. The instant film exhibits excellent mechanical properties, thanks to the optimized design of its internal structure and the optimal proportion between raw materials. The high - strength film material can withstand a certain amount of external force without breaking, ensuring the integrity of the product during transportation and storage. At the same time, its excellent flexibility and ductility make the film easy to be processed into various shapes to meet the requirements of different application scenarios. In the food industry, it can be used to wrap seasonings, coffee, tea bags, and even ready - to - eat foods, which is convenient for consumers and improves the user experience.

[0027] The pineapple - flavored instant film has excellent barrier properties. It can effectively block oxygen, moisture, and odors in the external environment from entering the package, thereby extending the shelf life of the packaged goods. This is crucial for maintaining the freshness and nutritional value of food. In addition, good barrier properties also contribute to the sustained release of pineapple fragrance, allowing consumers to experience a richer and more pleasant feeling during the process of enjoying food.

[0028] 2. The present invention uses modified hydroxypropyl methylcellulose, which is achieved through enzymatic treatment under specific conditions. The main purpose is to improve the structural characteristics of the original HPMC, thereby enhancing the mechanical properties and barrier properties of the final product. First, during the preparation process, composite enzyme A (including xylanase and transglutaminase) is activated at an appropriate temperature and added to the pre - dissolved HPMC solution for reaction. This process mainly utilizes the catalytic action of the enzyme to adjust the cross - linking degree and arrangement mode between HPMC molecular chains. Xylanase can degrade the xylan component in the cell wall, which helps to open the physical hindrance between HPMC molecules and promote more uniform dispersion; while transglutaminase can form covalent bonds between these molecules, increasing the intermolecular interaction force and making the overall structure of the material more compact. This structural optimization directly leads to the enhancement of the mechanical properties of the material. Enzymatic treatment may also cause changes in the microstructure, which will also affect the rigidity and toughness of the material. The close molecular arrangement reduces the free volume, decreases the gas and water vapor permeation rate, thereby enhancing the barrier effect of the material against oxygen, moisture, and other volatile substances. This improvement is particularly important for extending the shelf life of the packaged goods, especially in the field of food packaging.

[0029] 2. The modified xanthan gum of the present invention endows xanthan gum with new functional properties through graft copolymerization reaction and combination with whey protein, thereby enhancing the overall performance of the instant film. First, in the first step of the reaction, composite enzyme B (pectinase and laccase) was used, which were respectively responsible for decomposing naturally occurring pectin substances and catalyzing the polymerization reaction between phenolic compounds. When xanthan gum was blended with carboxymethyl cellulose (CMC) in an acetate buffer solution, the action of pectinase helped to open the molecular chain structure of xanthan gum, making it easier to react with other molecules; while laccase promoted the formation of new chemical bonds between xanthan gum and CMC, generating xanthan gum-CMC graft copolymer. The pre-gel formed by heating and denaturing whey protein was mixed with the above graft copolymer, and the two were further combined by adjusting the pH value. As a high-quality protein source, whey protein has good film-forming property and hydrophilicity. Its introduction not only enhances the mechanical strength of the material, but also improves the flexibility and transparency of the film. More importantly, the interaction between whey protein and xanthan gum-CMC graft copolymer forms a three-dimensional network structure, greatly improving the tear resistance and durability of the material. This new three-dimensional network structure significantly reduces the intermolecular voids and effectively prevents the influence of external environmental factors such as humidity and oxygen on the internal substances.

[0030] 3. The pineapple-flavored instant film provided by the present invention has excellent breath-freshening effect through scientific proportioning of ingredients such as D-mannitol, lactic acid bacteria complex powder, pullulan polysaccharide, etc. As a sweetener and humectant, D-mannitol can promote saliva secretion and reduce oral odor; lactic acid bacteria complex powder and lactic acid bacteria powder can regulate the balance of oral flora and inhibit the reproduction of odor-causing bacteria, reducing bad breath from the root cause; pineapple powder and pineapple essence endow the product with natural pineapple flavor, which is fresh and pleasant. At the same time, bromelain helps to decompose residual proteins in the oral cavity and reduce the source of odor. Modified hydroxypropyl methyl cellulose and modified xanthan gum as film-forming agents enable the product to dissolve quickly in the oral cavity, release active ingredients, and exert efficacy persistently. Glycerol as a humectant prevents oral dryness and enhances the comfort. This product has a fresh taste, is easy to use, can quickly improve breath, and is suitable for daily oral care. Detailed implementation manners

[0031] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0032] Example 1

[0033] This example provides a pineapple-flavored instant film, which comprises the following components in percentage by weight: D-mannitol 37%, lactic acid bacteria complex powder 22%, pullulan 7%, lactic acid bacteria powder 5%, pineapple powder 4%, modified hydroxypropyl methylcellulose 6%, glycerol 3%, pineapple essence 4%, modified xanthan gum 2%, and the balance is water.

[0034] The preparation method of the modified hydroxypropyl methylcellulose comprises the following steps:

[0035] (1) Dissolve complex enzyme A in water at 40 °C and let it stand for 10 minutes for activation;

[0036] (2) Disperse hydroxypropyl methylcellulose in water at 50 °C and stir until completely swollen to obtain an HPMC solution;

[0037] (3) Add the activated enzyme solution to the HPMC solution, stir and react at a constant temperature of 50 °C for 2 hours, raise the temperature to 85 °C and keep it for 10 minutes to inactivate the enzyme activity. After cooling, spray drying is carried out to obtain the modified hydroxypropyl methylcellulose.

[0038] Complex enzyme A comprises xylanase and transglutaminase with a weight ratio of 1:2.5.

[0039] The concentration of complex enzyme A in water is 0.5 wt%.

[0040] The concentration of hydroxypropyl methylcellulose in water is 3 wt%.

[0041] The hydroxypropyl methylcellulose is purchased from Guangdong Mingcheng Biotechnology Co., Ltd.

[0042] The preparation method of the modified xanthan gum comprises the following steps:

[0043] (1) Dissolve complex enzyme B in pH 5.0 acetate buffer solution, add xanthan gum (Anhui Zhonghong Biotechnology Co., Ltd.) and carboxymethyl cellulose, and premix at 40 °C for 10 minutes; react at 50 °C in an oxygen atmosphere for 4 hours, raise the temperature to 80 °C and keep it for 15 minutes to inactivate the enzyme, and dialyze to remove unreacted monomers with a cut-off molecular weight of 10 kDa to generate xanthan gum-CMC graft copolymer;

[0044] (2) Dissolve whey protein in water at a concentration of 4 wt%, heat at 80 °C for 20 minutes to induce denaturation to form a pre-gel. Mix the xanthan gum-CMC graft copolymer and the pre-gel in a volume ratio of 1:1, stir at 50 °C for 1 hour, add lactic acid to adjust the pH to 4.6, let it stand for 2 hours to complete gelation, dry and pulverize to obtain the modified xanthan gum.

[0045] Complex enzyme B comprises pectinase and laccase with a weight ratio of 1:2.5.

[0046] The concentration of complex enzyme B in pH 5.0 acetate buffer solution is 0.5 wt%.

[0047] The concentration of xanthan gum in acetic acid buffer solution with pH 5.0 is 3 wt%.

[0048] The concentration of carboxymethyl cellulose in acetic acid buffer solution with pH 5.0 is 1 wt%.

[0049] A preparation method of pineapple - flavored instant film, comprising the following steps:

[0050] (1) Pre - swelling of film - forming matrix: Heat water to 50 °C, add modified hydroxypropyl methylcellulose, pullulan and modified xanthan gum, shear - disperse at a high speed of 2000 rpm for 15 minutes to form a uniform glue solution; successively add glycerol and D - mannitol to the glue solution, and stir in a 40 °C constant - temperature water bath until completely dissolved;

[0051] (2) Gradient addition of functional components: Cool the glue solution to 25 °C, successively add lactic acid bacteria composite powder and lactic acid bacteria powder, stir with a low - speed paddle at 500 rpm for 15 minutes; add pineapple powder and pineapple essence, and use a vacuum homogenizer (-0.08 MPa, 5 minutes).

[0052] (3) Defoaming and coating - forming: Transfer the mixed slurry to a vacuum defoaming tank (-0.1 MPa, 30 minutes), use a slot coater (blade gap 0.6 mm), select an acrylic plate as the substrate, and the coating speed is 2 m / min; three - stage gradient drying: 35 °C, 40 °C, 30 °C in sequence), with a total duration of 15 minutes.

[0053] (4) Remove the dried film from the acrylic plate at room temperature to obtain the pineapple - flavored instant film.

[0054] Example 2

[0055] This example provides a pineapple - flavored instant film, comprising the following components in weight percentages: D - mannitol 35%, lactic acid bacteria composite powder 25%, pullulan 5%, lactic acid bacteria powder 8%, pineapple powder 3%, modified hydroxypropyl methylcellulose 9%, glycerol 2%, pineapple essence 5%, modified xanthan gum 1%, and the balance is water.

[0056] The preparation method of modified hydroxypropyl methylcellulose comprises the following steps:

[0057] (1) Dissolve composite enzyme A in water at 40 °C and let it stand for 10 minutes for activation;

[0058] (2) Disperse hydroxypropyl methylcellulose in water at 50 °C and stir until completely swollen to obtain HPMC glue solution;

[0059] (3) Add the activated enzyme solution to the HPMC solution, stir and react at a constant temperature of 50 °C for 2 hours, raise the temperature to 85 °C and maintain for 10 minutes to inactivate the enzyme activity. After cooling, spray dry to obtain modified hydroxypropyl methyl cellulose.

[0060] The composite enzyme A includes xylanase and transglutaminase with a weight ratio of 1:2.

[0061] The concentration of the composite enzyme A in water is 0.5 wt%.

[0062] The concentration of hydroxypropyl methyl cellulose in water is 3 wt%.

[0063] Hydroxypropyl methyl cellulose was purchased from Guangdong Mingcheng Biotechnology Co., Ltd.

[0064] The preparation method of the modified xanthan gum includes the following steps:

[0065] (1) Dissolve the composite enzyme B in a pH 5.0 acetate buffer solution, add xanthan gum and carboxymethyl cellulose, and premix at 40 °C for 10 minutes; react at 50 °C in an oxygen atmosphere for 4 hours, raise the temperature to 80 °C and maintain for 15 minutes to inactivate the enzyme, and dialyze to remove unreacted monomers with a cut-off molecular weight of 10 kDa to generate xanthan gum-CMC graft copolymer;

[0066] (2) Dissolve whey protein in water at a concentration of 4 wt%, heat at 80 °C for 20 minutes to induce denaturation to form a pre-gel, mix the xanthan gum-CMC graft copolymer and the pre-gel in a volume ratio of 1:1, stir at 50 °C for 1 hour, add lactic acid to adjust the pH to 4.6, let stand for 2 hours to complete gelation, dry and crush to obtain the modified xanthan gum.

[0067] The composite enzyme B includes pectinase and laccase with a weight ratio of 1:3.

[0068] The concentration of the composite enzyme B in the pH 5.0 acetate buffer solution is 0.5 wt%.

[0069] The concentration of xanthan gum in the pH 5.0 acetate buffer solution is 3 wt%.

[0070] The concentration of carboxymethyl cellulose in the pH 5.0 acetate buffer solution is 1 wt%.

[0071] The preparation method of the pineapple-flavored instant film includes the following steps:

[0072] (1) Pre-swelling of the film-forming matrix: Heat the water to 50 °C, add modified hydroxypropyl methyl cellulose, pullulan and modified xanthan gum, shear and disperse at a high speed of 2000 rpm for 15 minutes to form a uniform solution; sequentially add glycerol and D-mannitol to the solution, and stir in a 40 °C constant temperature water bath until completely dissolved;

[0073] (2) Gradual addition of functional components: Cool the glue solution to 25°C, and sequentially add the lactic acid bacteria composite powder and lactic acid bacteria powder. Stir at a low speed of 500 rpm with a paddle for 15 minutes; add pineapple powder and pineapple essence, and use a vacuum homogenizer (-0.08 MPa, 5 minutes).

[0074] (3) Defoaming and coating forming: Transfer the mixed slurry to a vacuum defoaming tank (-0.1 MPa, 30 minutes), and use a slot coater (blade gap 0.6 mm). The substrate is selected as an acrylic plate, and the coating speed is 2 m / min; Three-stage gradient drying: 35°C, 40°C, 30°C in sequence), with a total duration of 15 minutes.

[0075] (4) Remove the dried film from the acrylic plate at room temperature to obtain the instant pineapple-flavored film.

[0076] Example 3

[0077] This example provides an instant pineapple-flavored film, including the following components in weight percentages: D-mannitol 40%, lactic acid bacteria composite powder 20%, pullulan 10%, lactic acid bacteria powder 3%, pineapple powder 7%, modified hydroxypropyl methylcellulose 4%, glycerol 5%, pineapple essence 2%, modified xanthan gum 3%, and the balance is water.

[0078] The preparation method of the modified hydroxypropyl methylcellulose includes the following steps:

[0079] (1) Dissolve the composite enzyme A in water at 40°C and let it stand for 10 minutes for activation;

[0080] (2) Disperse hydroxypropyl methylcellulose in water at 50°C and stir until completely swollen to obtain the HPMC glue solution;

[0081] (3) Add the activated enzyme solution to the HPMC glue solution, stir and react at a constant temperature of 50°C for 2 hours, raise the temperature to 85°C and keep it for 10 minutes to inactivate the enzyme activity. After cooling, spray dry to obtain the modified hydroxypropyl methylcellulose.

[0082] The composite enzyme A includes xylanase and transglutaminase in a weight ratio of 1:3.

[0083] The concentration of the composite enzyme A in water is 0.5 wt%.

[0084] The concentration of hydroxypropyl methylcellulose in water is 3 wt%.

[0085] The hydroxypropyl methylcellulose is purchased from Guangdong Mingcheng Biotechnology Co., Ltd.

[0086] The preparation method of the modified xanthan gum includes the following steps:

[0087] (1) Dissolve complex enzyme B in acetic acid buffer solution with pH 5.0, add xanthan gum and carboxymethyl cellulose, and premix at 40 °C for 10 minutes; react at 50 °C in an oxygen atmosphere for 4 hours, raise the temperature to 80 °C and maintain for 15 minutes to inactivate the enzyme, and dialyze to remove unreacted monomers with a molecular weight cut-off of 10 kDa to generate xanthan gum-CMC graft copolymer;

[0088] (2) Dissolve whey protein in water at a concentration of 4 wt%, heat at 80 °C for 20 minutes to induce denaturation to form a pre-gel, mix the xanthan gum-CMC graft copolymer and the pre-gel in a volume ratio of 1:1, stir at 50 °C for 1 hour, add lactic acid to adjust the pH to 4.6, let stand for 2 hours to complete gelation, dry and crush to obtain modified xanthan gum.

[0089] Complex enzyme B includes pectinase and laccase with a weight ratio of 1:2.

[0090] The concentration of complex enzyme B in acetic acid buffer solution with pH 5.0 is 0.5 wt%.

[0091] The concentration of xanthan gum in acetic acid buffer solution with pH 5.0 is 3 wt%.

[0092] The concentration of carboxymethyl cellulose in acetic acid buffer solution with pH 5.0 is 1 wt%.

[0093] A preparation method of pineapple-flavored instant film, comprising the following steps:

[0094] (1) Pre-swelling of film-forming matrix: Heat water to 50 °C, add modified hydroxypropyl methylcellulose, pullulan polysaccharide and modified xanthan gum, and disperse at high speed with a shear rate of 2000 rpm for 15 minutes to form a uniform colloidal solution; sequentially add glycerol and D-mannitol to the colloidal solution, and stir in a constant temperature water bath at 40 °C until completely dissolved;

[0095] (2) Gradient addition of functional components: Cool the colloidal solution to 25 °C, sequentially add lactic acid bacteria complex powder and lactic acid bacteria powder, and stir with a low-speed paddle at 500 rpm for 15 minutes; add pineapple powder and pineapple essence, and use a vacuum homogenizer (-0.08 MPa, 5 minutes).

[0096] (3) Defoaming and coating forming: Transfer the mixed slurry to a vacuum defoaming tank (-0.1 MPa, 30 minutes), use a slot coater (blade gap 0.6 mm), select an acrylic plate as the substrate, and the coating speed is 2 m / min; three-stage gradient drying: 35 °C, 40 °C, 30 °C in sequence), with a total duration of 15 minutes.

[0097] (4) Take the dried film off the acrylic plate at room temperature to obtain the pineapple-flavored instant film.

[0098] Comparative Example 1

[0099] The difference between this comparative example and Example 1 is that complex enzyme A is replaced by transglutaminase.

[0100] Comparative Example 2

[0101] The difference between this comparative example and Example 1 is that complex enzyme B is replaced by laccase.

[0102] Comparative Example 3

[0103] The difference between this comparative example and Example 1 is that the preparation method of modified xanthan gum includes the following steps: Dissolve complex enzyme B in acetic acid buffer solution with pH 5.0, add xanthan gum and carboxymethyl cellulose, and premix at 40 °C for 10 minutes; React at 50 °C in an oxygen atmosphere for 4 hours, raise the temperature to 80 °C and keep for 15 minutes to inactivate the enzyme, dialyze to remove unreacted monomers, with a cut-off molecular weight of 10 kDa, to generate xanthan gum-CMC graft copolymer, dry and pulverize to obtain modified xanthan gum.

[0104] Comparative Example 4

[0105] The difference between this comparative example and Example 1 is that the preparation method of modified xanthan gum includes the following steps:

[0106] (1) Dissolve xanthan gum in acetic acid buffer solution with pH 5.0, and the concentration of xanthan gum in acetic acid buffer solution with pH 5.0 is 3 wt%, to obtain xanthan gum solution;

[0107] (2) Dissolve whey protein in water with a concentration of 4 wt%, heat at 80 °C for 20 minutes to induce denaturation to form a pre-gel, mix the xanthan gum solution and the pre-gel in a volume ratio of 1:1, stir at 50 °C for 1 hour, add lactic acid dropwise to adjust the pH to 4.6, stand for 2 hours to complete gelation, dry and pulverize to obtain modified xanthan gum.

[0108] Comparative Example 5

[0109] The difference between this comparative example and Example 1 is that modified hydroxypropyl methylcellulose is replaced by hydroxypropyl methylcellulose, purchased from Guangdong Mingcheng Biotechnology Co., Ltd.

[0110] Comparative Example 6

[0111] The difference between this comparative example and Example 1 is that modified xanthan gum is replaced by xanthan gum, Anhui Zhonghong Biotechnology Co., Ltd.

[0112] Performance Test

[0113] The tensile strength, elongation at break, and water vapor transmission rate of the pineapple-flavored instant films of Examples 1-3 and Comparative Examples 1-6 were measured according to GB / T 30768-2014, as shown in Table 1.

[0114] Table 1 Performance Test Results

[0115]

[0116]

[0117] As can be seen from Table 1, the mechanical properties of the pineapple-flavored instant film prepared in Examples 1-3 of the present invention are excellent and the barrier property is high.

[0118] In Comparative Example 1, composite enzyme A was replaced with a single enzyme, and the mechanical properties of the pineapple-flavored instant film decreased and the barrier property became worse.

[0119] In Comparative Example 2, composite enzyme B was replaced with a single enzyme, and the mechanical properties of the pineapple-flavored instant film decreased and the barrier property became worse.

[0120] In Comparative Example 3, only the modified xanthan gum was enzymatically hydrolyzed, and the mechanical properties of the pineapple-flavored instant film decreased and the barrier property became worse.

[0121] In Comparative Example 4, only the modified xanthan gum reacted with whey protein, and the mechanical properties of the pineapple-flavored instant film decreased and the barrier property became worse.

[0122] In Comparative Example 5, the modified hydroxypropyl methylcellulose was replaced with hydroxypropyl methylcellulose, and the mechanical properties of the pineapple-flavored instant film decreased and the barrier property became worse.

[0123] In Comparative Example 6, the modified xanthan gum was replaced with xanthan gum, and the mechanical properties of the pineapple-flavored instant film decreased and the barrier property became worse.

[0124] The above are the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A pineapple - flavored instant film, characterized in that, It comprises components in the following weight percentages: 35-40% of D-mannitol, 20-25% of lactic acid bacteria complex powder, 5-10% of pullulan, 3-8% of lactic acid bacteria powder, 3-7% of pineapple powder, 4-9% of modified hydroxypropyl methylcellulose, 2-5% of glycerol, 2-5% of pineapple essence, 1-3% of modified xanthan gum, and the balance is water.

2. The instant soluble film with pineapple flavor according to claim 1, wherein, The preparation method of the modified hydroxypropyl methylcellulose comprises the following steps: (1) Dissolve complex enzyme A in water at 35-40 °C, stand still for activation to obtain an activated enzyme solution; (2) Disperse hydroxypropyl methylcellulose in water at 45-50 °C, stir until completely swollen to obtain an HPMC gum solution; (3) Add the activated enzyme solution to the HPMC gum solution, carry out a constant-temperature stirring reaction at 45-50 °C for 2-3 hours, inactivate the enzyme activity, cool, and then spray dry to obtain the modified hydroxypropyl methylcellulose.

3. The instant dissolving film with pineapple flavor according to claim 2, wherein The complex enzyme A comprises xylanase and transglutaminase in a weight ratio of 1:(2-3).

4. The instant dissolving film with pineapple flavor according to claim 2, wherein The concentration of the complex enzyme A in water is 0.5-1.0 wt%.

5. The instant dissolving film with pineapple flavor according to claim 2, characterized in that, The concentration of hydroxypropyl methylcellulose in water is 3-5 wt%.

6. The instant dissolving film with pineapple flavor according to claim 1, wherein The preparation method of the modified xanthan gum comprises the following steps: (1) Dissolve complex enzyme B in an acetate buffer solution, add xanthan gum and carboxymethyl cellulose, and premix; react at 50-55 °C in an oxygen atmosphere for 4-6 hours, inactivate the enzyme, and dialyze with a cut-off molecular weight of 10 kDa to generate a xanthan gum-CMC graft copolymer; (2) Dissolve whey protein in water, heat to induce denaturation to form a pre-gel, mix the xanthan gum-CMC graft copolymer with the pre-gel, stir at 50-55 °C for 1-2 hours, add lactic acid dropwise to adjust the pH, stand still for 2-3 hours to complete gelation, dry, and pulverize to obtain the modified xanthan gum.

7. The instant dissolving film with pineapple flavor according to claim 6, characterized in that, The complex enzyme B comprises pectinase and laccase in a weight ratio of 1:(2-3).

8. The instant dissolving film with pineapple flavor according to claim 6, wherein The concentration of the complex enzyme B in the acetate buffer solution is 0.5-0.7 wt%.

9. The instant dissolving film with pineapple flavor according to claim 6, wherein, The concentration of xanthan gum in the acetate buffer solution is 3-3.5 wt%; the concentration of carboxymethyl cellulose in the acetate buffer solution is 1-2 wt%.

10. A method for preparing a pineapple - flavored instant film according to any one of claims 1 - 9, characterized in that, It comprises the following steps: (1) Pre-swelling of the film-forming matrix: Heat water to 50-60 °C, add modified hydroxypropyl methylcellulose, pullulan and modified xanthan gum, shear and disperse to form a uniform gum solution; sequentially add glycerol and D-mannitol to the gum solution, and carry out constant-temperature water bath stirring until completely dissolved; (2) Gradient addition of functional components: Cool the gum solution to 25-30 °C, sequentially add lactic acid bacteria complex powder and lactic acid bacteria powder, and stir with a low-speed paddle; add pineapple powder and pineapple essence, and homogenize with a vacuum homogenizer; (3) Defoaming and coating and forming: Transfer the mixed slurry to a vacuum defoaming tank for vacuum defoaming, coat with a slot coater, select an acrylic plate as the substrate, and ensure that the water content of the film ≤ 5%; (4) Take the dried film off the acrylic plate at room temperature to obtain a pineapple-flavored instant film.

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