Modified starch-lipid compound basement membrane as well as preparation method and application thereof

Abstract

The invention provides a modified starch-lipid compound basement membrane as well as a preparation method and application thereof. Pea starch is used as a raw material, starch is subjected to double hydrophobic modification through starch OSA esterification and starch-lipid non-covalent compounding, and the retrogradation resistance and hydrophobicity of the starch are synergistically improved. The packaging film prepared from the OSA starch-lipid compound has better retrogradation resistance, surface hydrophobicity, water vapor barrier property and mechanical property than the traditional natural starch-based film, can effectively reduce the loss of moisture and other nutrient substances of the red grapes under the conditions of normal temperature and normal humidity, and inhibits the appearance of the red grapes from deformation and mildew (12d); and the fresh-keeping agent has excellent fresh-keeping capability and anti-mildew effect. The preparation method disclosed by the invention is simple, safe and green, and the prepared modified starch-lipid compound based film has the advantages of being edible, biodegradable, water-blocking, excellent in mechanical property and the like, has a remarkable effect in the aspect of fresh keeping of picked fruits and vegetables, and has a huge application prospect in the aspects of packaging, isolating materials and the like.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of packaging materials, especially the field of food preservation packaging materials, and specifically relates to a modified starch-lipid complex, a packaging film thereof, a preparation method and application thereof. More specifically, the present application relates to a modified starch-lipid complex formula, a base film, a fresh-keeping packaging film product, a preparation method thereof, and application thereof in food, pharmaceutical packaging materials, isolation materials and the like. BACKGROUND

[0002] Fresh fruits and vegetables are rich in nutrients and play an important role in maintaining human health and preventing chronic diseases. At present, about 30% of fruits are lost due to spoilage during the postharvest stage. Reducing postharvest loss of fruits and vegetables has always been one of the problems to be solved in the food field. Therefore, a number of technologies have been applied to postharvest preservation of fruits and vegetables, such as plastic packaging, coating preservation, low-temperature cold storage and modified atmosphere technology. In addition, agricultural mulch and vegetable greenhouse film and other isolation materials also play an important role in fruit and vegetable planting.

[0003] For a long time, plastic packaging has dominated the development of the packaging industry due to its convenience and excellent performance. However, plastic film is a petroleum-based material, which is non-renewable and non-biodegradable, leading to problems such as energy crisis, environmental pollution of oceans and soil, and harm to human health. Therefore, it is urgent to develop biologically friendly, biodegradable and excellent performance biopolymer-based packaging materials.

[0004] Starch has the advantages of wide source, low cost, high safety, environmental friendliness and easy biodegradability. However, the inherent high hydrophilicity and easy retrogradation of natural starch result in poor water resistance, low water barrier performance and poor mechanical properties of starch-based films, which greatly limits the application of starch-based packaging materials.

[0005] Octenyl succinic anhydride (OSA) is a starch esterification modification reagent in the food industry. However, how to further prepare OSA modified starch-lipid complex film base material from OSA modified starch, and finally prepare base film, has not been reported. More importantly, the application of OSA modified starch-lipid complex base film to packaging materials and isolation materials has not been reported, such as for food preservation materials.

[0006] Therefore, the present application proposes to prepare biodegradable starch-based film with excellent barrier properties and mechanical properties by compounding OSA starch and lipids, which has important practical significance and social and economic value for solving the problem of poor application effect of traditional natural starch-based film in food preservation and isolation materials due to its poor water resistance and mechanical properties.

[0007] Explanation of terms:

[0008] Mold: The mold referred to in the present application specifically refers to a base film mold, which refers to a mold used for preparing a modified starch-lipid complex base film, and a square flat dish of 240*240mm is used. 2 Summary SUMMARY

[0009] Therefore, the present application aims to provide a modified starch-lipid complex base film, a preparation method and application thereof. The prepared biodegradable starch-lipid complex base film has excellent anti-retrogradation performance, surface hydrophobicity, water vapor barrier performance and mechanical properties such as tensile strength and elongation at break, thereby improving the preservation effect on fruits and vegetables, so as to solve the problem of limited application effect caused by the insufficient water resistance and mechanical properties of traditional natural starch base packaging film.

[0010] In order to overcome the shortcomings of the prior art and achieve the above purpose, the present application is realized by the following technical scheme:

[0011] The present application improves the hydrophobicity and elongation at break of the starch base film through esterification. On the other hand, the applicant found that the complex of starch and lipid is an effective strategy to improve the water vapor barrier performance of the starch base film. The amylose in starch can embed suitable lipid molecules to form a single helix structure of starch-lipid complex. Compared with the natural starch base film, the film prepared from the starch-lipid complex has lower water vapor transmission rate and higher tensile strength.

[0012] Firstly, in view of the problems of traditional natural starch base film such as humidity sensitivity, high water vapor transmission rate and poor mechanical properties, the inventors select pea starch with high amylose content and good film-forming property as raw material, and perform OSA esterification modification on the starch. The introduction of OSA groups on the starch molecular chain can enhance the hydrophobicity of the starch, and improve the hydrophobicity and anti-retrogradation of the starch.

[0013] Next, the OSA starch is combined with lipid to prepare a modified starch-lipid complex, which further improves the hydrophobicity and anti-retrogradation of the film-forming raw material.

[0014] Continuing, the modified starch-lipid complex base film is prepared by using a casting method, and the complex base film with excellent anti-retrogradation performance, surface hydrophobicity, water resistance and mechanical properties is selected to prepare a biodegradable preservation packaging bag. The packaging bag is applied to the storage and preservation of food such as fruits and vegetables, meat and seafood, for example, red apples, to evaluate the preservation effect of the packaging bag on fruits and vegetables.

[0015] The present application provides a modified starch-lipid complex and a base film prepared from the complex, wherein the modified starch is prepared from pea starch as raw material to form octenyl succinic anhydride modified starch.

[0016] The modified starch-lipid complex base film according to the present application is characterized in that the XRD diffraction pattern thereof has weak or no obvious diffraction peaks at 5°, 17°, 22° and 24°, and has no strong diffraction peak.

[0017] The starch-lipid complex and the base film thereof according to the present application can be prepared by the following method:

[0018] S1: starch, water are mixed, octenyl succinic anhydride is added for reaction, centrifugation, washing of the precipitate, drying, to obtain modified starch

[0019] S2: modified starch, water are mixed, lipid is added, heating, then cooling, to obtain paste, drying, grinding, to obtain modified starch-lipid complex. The lipid can be selected from C12-C18 saturated long-chain fatty acid, C12-C18 saturated long-chain fatty acid monoglyceride, or one or more of them; wherein the lipid is lauric acid, palmitic acid, stearic acid, lauric acid monoglyceride, palmitic acid monoglyceride, stearic acid monoglyceride; preferably lauric acid. The mass ratio of lipid to modified starch is 1:(20-100), preferably 1:50. S3: modified starch-lipid complex, water, glycerol are mixed, heating, poured into a base film mold, drying, to obtain modified starch-lipid complex base film. The mass ratio of modified starch-lipid complex: glycerol: water is 1:0.3:(20-100); preferably 1:0.3:50. The heating temperature is 85-95℃, preferably 90℃.

[0020] Further, the starch-lipid complex and the base film thereof according to the present application can be prepared by the following method:

[0021] S1: starch, water are mixed, octenyl succinic anhydride is added for reaction, centrifugation, washing of the precipitate, drying, to obtain modified starch

[0022] S2: modified starch, water are mixed, lipid is added, heating for 0.5-5h, cooling, to obtain paste, drying for 2-24h, grinding, to obtain modified starch-lipid complex.

[0023] S3: modified starch-lipid complex, water, glycerol are mixed, stirring and heating at 85-95℃ for 10-120min, poured into a base film mold, drying for 2-24h, to obtain modified starch-lipid complex base film.

[0024] Further, the starch-lipid complex and the base film thereof according to the present application can be prepared by the following method:

[0025] S1: 0.75 mol / L NaOH solution is added to a 30-50 wt% starch suspension, the pH of the system is adjusted to weak alkaline, 1-10% octenyl succinic anhydride relative to the dry mass of the starch is added dropwise at 35°C, and the reaction is carried out for 4h at a stirring rate of 350 rpm; the reaction is terminated by adjusting the pH to weak acid with 0.50 mol / L HCl; after centrifugation, the precipitate is washed with water to neutral, and dried at 40°C for 8-12h to obtain the octenyl succinic anhydride modified starch.

[0026] wherein: the starch is pea starch, the concentration of the starch suspension is 40%, and the addition amount of the octenyl succinic anhydride is 3-9% of the dry mass of the starch; the weak alkaline pH is 8.0-8.5, and the weak acid pH is 6.0.

[0027] S2: the modified starch is mixed with water to prepare a 5-15 wt% starch suspension, then lipid is added, heated at a constant temperature of 90°C and a stirring rate of 350 rpm for 1-2h, cooled to 25°C, and the obtained paste is dried at 40°C for 6-10h, ground and sieved to prepare a modified starch-lipid complex.

[0028] S3: the modified starch-lipid complex, water and glycerol are mixed and heated at 85-95°C under stirring for 30min, then poured into a base film mold and dried for 8-12h to obtain a modified starch-lipid complex base film.

[0029] The modified starch-lipid complex and the base film thereof provided by the application can be used to prepare various packaging materials and isolation materials.

[0030] Further, the food preservation material can be prepared in various forms for the convenience of use in the food industry, such as a preservative film, a preservative bag and a disposable food bag, and can be used for the preservation of most foods such as fruits, vegetables, meat and seafood.

[0031] The application can also be used to prepare medicine packaging bags including but not limited to medicine packaging bags, special medical food packaging bags and health product packaging bags.

[0032] Compared with the prior art, the application has the following advantages:

[0033] (1) The octenyl succinic anhydride modified starch-lipid complex base film uses food materials as raw and auxiliary materials, mainly OSA starch and lipids, which have the advantages of wide source, low cost, safety, non-toxicity and biodegradability.

[0034] (2) The starch esterification and starch-lipid complex are used for double hydrophobic modification of starch in the application, which can improve the anti-regeneration, surface hydrophobicity and water vapor barrier performance of the starch-based film;

[0035] (3) The modified starch-lipid complex-based film prepared in the application has better tensile strength, elongation at break and other mechanical properties compared with the natural starch film;

[0036] (4) Compared with the traditional natural starch-based packaging bag, the fresh-keeping effect of the application is very outstanding, the water resistance and mechanical properties of the prepared fresh-keeping packaging bag are higher, the fruit moisture and nutrient loss can be better reduced, and better fresh-keeping effect can be achieved.

[0037] (5) The application uses natural pea as a starting raw material, has low cost, the whole process is free of harsh conditions, can be used for industrialized mass production, meets the environmental protection needs of a populous country, and has very economical cost.

[0038] In summary, the preparation method of the application is simple, safe and green, the water resistance and mechanical properties of the starch-based film are excellent, the prepared film and packaging bag have remarkable fresh-keeping effect on fruits and vegetables, meat, seafood and the like, especially on postharvest preservation of fruits and vegetables, and therefore have great application prospect in packaging and isolation materials. BRIEF DESCRIPTION OF DRAWINGS

[0039] Figure 1 Preparation process of the modified starch-lipid complex-based fresh-keeping packaging film;

[0040] Figure 2 X-ray diffraction patterns of examples 1-2 and comparative examples 1-3;

[0041] Figure 3 Appearance of red pitaya packaged by examples 1-2 and comparative examples 1-3;

[0042] Figure 4 Mass loss rate of red pitaya packaged by examples 1-2 and comparative examples 1-3;

[0043] Figure 5 Vitamin C content of red pitaya packaged by examples 1-2 and comparative examples 1-3; C

[0044] Figure 6 Nuclear magnetic resonance imaging of red pitaya packaged by examples 1-2 and comparative examples 1-3. DETAILED DESCRIPTION

[0045] ​Unless otherwise defined, the technical terms used in the following examples have the same meanings as commonly understood by those skilled in the art to which this application belongs. The test reagents used in the following examples are all conventional biochemical reagents unless otherwise specified; the experimental methods used are all conventional methods unless otherwise specified.

[0046] The application will be described in detail below with reference to the examples, but the following description is not intended to limit the scope of protection of the application.

[0047] Preparation of 3% OSA pea starch-2% lauric acid complex-based film

[0048] (1) 0.75 mol / L NaOH solution was added to a 40 wt% natural pea starch suspension, the pH was adjusted to weak alkaline, and 3% OSA relative to the dry mass of the starch was added dropwise at 35°C, and the reaction was carried out for 4 h at a stirring rate of 350 rpm to modify the starch by esterification; the reaction was terminated by adjusting the pH to weak acid with 0.50 mol / L HCl; the precipitate was washed with water to neutral after centrifugation, and dried at 40°C for 8 h to prepare 3% OSA pea starch.

[0049] (2) The OSA pea starch was mixed with water to prepare a 10 wt% starch suspension, and then 2% lauric acid relative to the mass of the starch was added, and the reaction was carried out at 90°C under stirring at a stirring rate of 350 rpm for 1 h, and then cooled to 25°C; the obtained paste was dried at 40°C for 8 h, ground and sieved to prepare 3% OSA pea starch-2% lauric acid complex;

[0050] (3) The OSA pea starch-lipid complex: glycerol: water were mixed uniformly in a mass ratio of 1:0.3:50, heated and stirred at 90°C for 30 min, and then poured into a mold and dried for 8 h to prepare 3% OSA pea starch-2% lauric acid complex-based film.

[0051] Preparation of 3% OSA pea starch-2% lauric acid complex-based film

[0052] (1) 0.75 mol / L NaOH solution was added to a 40 wt% natural pea starch suspension, the pH was adjusted to weak alkaline, and 3% OSA relative to the dry mass of the starch was added dropwise at 35°C, and the reaction was carried out for 4 h at a stirring rate of 350 rpm to modify the starch by esterification; the reaction was terminated by adjusting the pH to weak acid with 0.50 mol / L HCl; the precipitate was washed with water to neutral after centrifugation, and dried at 40°C for 8 h to prepare 3% OSA pea starch.

[0053] (2) 9% OSA pea starch-2% lauric acid complex was prepared by mixing OSA pea starch with water to form a 10 wt% starch suspension, then adding 2% lauric acid relative to the mass of the starch, heating the reaction at 90°C with a stirring rate of 350 rpm for 1 h, then cooling to 25°C, drying the resulting paste at 40°C for 8 h, grinding and sieving.

[0054] (3) 9% OSA pea starch-2% lauric acid complex film was prepared by mixing OSA pea starch-lipid complex: glycerol: water at a mass ratio of 1:0.3:50, stirring and heating at 90°C for 30 min, then pouring into a mold and drying for 8 h.

[0055] Example 39% OSA pea starch-2% stearic acid complex film

[0056] (1) 9% OSA pea starch was prepared by adding 0.75 mol / L NaOH solution to a 40 wt% natural pea starch suspension, adjusting the pH to weak alkaline, adding 9% OSA relative to the dry mass of the starch at 35°C dropwise, reacting for 4 h with a stirring rate of 350 rpm to modify the starch by esterification, adding 0.50 mol / L HCl to adjust the pH to weak acid to terminate the reaction, washing the precipitate with water to neutral after centrifugation, and drying at 40°C for 8 h.

[0057] (2) 9% OSA pea starch-2% stearic acid complex was prepared by mixing OSA pea starch with water to form a 10 wt% starch suspension, then adding 2% stearic acid relative to the mass of the starch, heating the reaction at 90°C with a stirring rate of 350 rpm for 1 h, then cooling to 25°C, drying the resulting paste at 40°C for 8 h, grinding and sieving.

[0058] (3) 9% OSA pea starch-2% stearic acid complex film was prepared by mixing OSA pea starch-lipid complex: glycerol: water at a mass ratio of 1:0.3:50, stirring and heating at 90°C for 30 min, then pouring into a mold and drying for 8 h.

[0059] Example 49% OSA pea starch-5% lauric acid complex film

[0060] (1) 9% OSA pea starch was prepared by adding 0.75 mol / L NaOH solution to a 40 wt% natural pea starch suspension, adjusting the pH to weak alkaline, adding 9% OSA relative to the dry mass of the starch at 35°C dropwise, reacting for 4 h with a stirring rate of 350 rpm to modify the starch by esterification, adding 0.50 mol / L HCl to adjust the pH to weak acid to terminate the reaction, washing the precipitate with water to neutral after centrifugation, and drying at 40°C for 8 h.

[0061] (2) The OSA pea starch was mixed with water to prepare a 10 wt% starch suspension, then 5% lauric acid was added relative to the mass of the starch, heated at 90°C with a stirring rate of 350 rpm for 1 h, then cooled to 25°C, the obtained paste was dried at 40°C for 8 h, ground and sieved to prepare a 9% OSA pea starch-5% lauric acid complex;

[0062] (3) The OSA pea starch-lipid complex: glycerol: water was mixed uniformly at a mass ratio of 1:0.3:50, heated at 90°C with stirring for 30 min, then poured into a mold and dried for 8 h to prepare a 9% OSA pea starch-5% lauric acid complex-based film.

[0063] Example 5 9% OSA pea starch-5% lauric acid complex-based film

[0064] (1) A 0.75 mol / L NaOH solution was added to a 40 wt% natural pea starch suspension, the pH was adjusted to weak alkaline, 9% OSA was added dropwise relative to the dry mass of the starch at 35°C, the starch was esterified and modified at a stirring rate of 350 rpm for 4 h; the reaction was terminated by adding 0.50 mol / L HCl to adjust the pH to weak acid; after centrifugation, the precipitate was washed with water to neutral, dried at 40°C for 8 h to prepare 9% OSA pea starch.

[0065] (2) The OSA pea starch was mixed with water to prepare a 10 wt% starch suspension, then 2% lauric acid monoglyceride was added relative to the mass of the starch, heated at 90°C with a stirring rate of 350 rpm for 1 h, then cooled to 25°C, the obtained paste was dried at 40°C for 8 h, ground and sieved to prepare a 9% OSA pea starch-2% lauric acid monoglyceride complex;

[0066] (3) The OSA pea starch-lipid complex: glycerol: water was mixed uniformly at a mass ratio of 1:0.3:50, heated at 90°C with stirring for 30 min, then poured into a mold and dried for 8 h to prepare a 9% OSA pea starch-2% lauric acid monoglyceride complex-based film.

[0067] Example 6 9% OSA pea starch-2% lauric acid monoglyceride complex-based film

[0068] (1) A 0.75 mol / L NaOH solution was added to a 40 wt% natural pea starch suspension, the pH was adjusted to weak alkaline, 9% OSA was added dropwise relative to the dry mass of the starch at 35°C, the starch was esterified and modified at a stirring rate of 350 rpm for 4 h; the reaction was terminated by adding 0.50 mol / L HCl to adjust the pH to weak acid; after centrifugation, the precipitate was washed with water to neutral, dried at 40°C for 8 h to prepare 9% OSA pea starch.

[0069] (2) OSA pea starch was mixed with water to prepare a 10 wt% starch suspension, then 2% stearic acid monoglyceride was added relative to the mass of the starch, heated and reacted at 90°C for 1 h under stirring at a speed of 350 rpm, then cooled to 25°C, and the obtained paste was dried at 40°C for 8 h, ground and sieved to prepare a 9% OSA pea starch-2% stearic acid monoglyceride complex;

[0070] (3) OSA pea starch-lipid complex: glycerol: water were mixed uniformly at a mass ratio of 1:0.3:50, heated and stirred at 90°C for 30 min, then poured into a mold and dried for 8 h to prepare a 9% OSA pea starch-2% stearic acid monoglyceride complex-based film.

[0071] Comparative Example 1 Natural pea starch-based film

[0072] Natural pea starch: glycerol: water were mixed uniformly at a mass ratio of 1:0.3:50, heated and stirred at 90°C for 30 min, then poured into a mold and dried for 8 h to prepare a natural pea starch-based film.

[0073] Comparative Example 2 3% OSA pea starch-based film

[0074] A 0.75 mol / L NaOH solution was added to a 40 wt% natural pea starch suspension, the pH was adjusted to weak alkaline, 3% OSA was added relative to the dry mass of the starch, and the reaction was carried out at 35°C for 4 h under stirring at a speed of 350 rpm to modify the starch by esterification; 0.50 mol / L HCl was added to adjust the pH to weak acid to terminate the reaction; after centrifugation, the precipitate was washed with water to neutral, and dried at 40°C for 8 h to prepare 3% OSA pea starch. OSA pea starch: glycerol: water were mixed uniformly at a mass ratio of 1:0.3:50, heated and stirred at 90°C for 30 min, then poured into a mold and dried for 8 h to prepare a 3% OSA pea starch-based film.

[0075] Comparative Example 3 Pea starch-2% lauric acid complex-based film

[0076] Natural pea starch was mixed with water to prepare a 10 wt% starch suspension, then 2% lauric acid was added relative to the mass of the starch, heated and reacted at 90°C for 1 h under stirring at a speed of 350 rpm, then cooled to 25°C, and the obtained paste was dried at 40°C for 8 h, ground and sieved to prepare a natural pea starch-2% lauric acid complex. Natural pea starch-lipid complex: glycerol: water were mixed uniformly at a mass ratio of 1:0.3:50, heated and stirred at 90°C for 30 min, then poured into a mold and dried for 8 h to prepare a natural pea starch-2% lauric acid complex-based film.

[0077] Example 7 Characterization of crystal structure

[0078] The diffraction patterns of the starch-based films were determined using a D8 Advance X-ray diffractometer from Bruker, Germany. All samples were equilibrated in a closed container with saturated sodium chloride solution at 25 °C for 3 days before analysis. The results are shown in Figure 1. Figure 2

[0079] The starch experienced gelatinization and retrogradation during the film formation process, and the starch crystal structure was destroyed to form B-type retrograded starch crystals (XRD peaks at 5°, 17°, 22° and 24°), the greater the diffraction peak, the higher the degree of retrogradation. The results showed that compared with Comparative Examples 1-3, the modified starch-lipid complex-based film prepared in Example 1-2 had no obvious diffraction peaks at 5°, 17°, 22° and 24°, indicating that the OSA starch-lipid complex-based film had stronger anti-retrogradation performance compared with the natural starch-based film, the OSA starch-based film and the natural starch-lipid complex-based film.

[0080] Example 8 Test of contact angle

[0081] The PGX-50757 dynamic contact angle tester from FIBRO, Sweden was used to determine the contact angle of the film to water droplets, which characterized the surface hydrophobicity of the film to water. The results are shown in Table 1.

[0082] Table 1 Surface hydrophobicity, water vapor barrier property and mechanical property of starch-based film

[0083]

[0084] The results showed that compared with Comparative Examples 1-3, the contact angle of the modified starch-lipid complex-based film prepared in Example 1-2 was more than 90°, far exceeding the contact angle of the starch-based film prepared in the comparative examples, indicating that the OSA starch-lipid complex-based film had higher surface hydrophobicity compared with the natural starch-based film, the OSA starch-based film and the natural starch-lipid complex-based film.

[0085] Example 9 Test of water vapor barrier property

[0086] The C430H water vapor transmission rate tester from Jinan Lanlight Company was used for determination. The results are shown in Table 1.

[0087] The results showed that compared with Comparative Examples 1-3, the water vapor transmission coefficient of the modified starch-lipid complex-based film prepared in Example 1-2 was smaller, indicating that the OSA starch-lipid complex-based film had higher water vapor barrier property compared with the natural starch-based film, the OSA starch-based film and the natural starch-lipid complex-based film.

[0088] Example 10 Test of mechanical property

[0089] ​The membrane samples were equilibrated for 12 hours at a temperature of 23±1℃ and a relative humidity of 50±1%. The tensile strength (MPa), elongation at break (%), and Young's modulus (MPa) of the membrane were measured using a universal testing machine (QJ211S) from Shanghai Qingji Co., Ltd., at a tensile rate of 10 mm / min. The results are shown in Table 1.

[0090] The results showed that, compared with Comparative Example 1, the modified starch-lipid composite films prepared in Examples 1-2 had higher tensile strength and elongation at break; compared with Comparative Example 2, the modified starch-lipid composite films prepared in Examples 1-2 had greater tensile strength; and compared with Comparative Example 3, the modified starch-lipid composite films prepared in Examples 1-2 had greater elongation at break. These results indicate that starch OSA esterification combined with starch-lipid composites can effectively improve the mechanical properties of starch-based films.

[0091] Example 11: Test of preservation performance

[0092] Cut the starch-based film into two 230×230mm pieces. 2 The film was used to prepare rectangular packaging bags using a heat-sealing machine. Fresh red grapes were placed in the packaging bags and sealed with a heat sealer. Unpackaged red grapes were used as a control. The bags were stored in a constant temperature and humidity chamber for 12 days at a temperature of 25°C and a relative humidity of 55%. The appearance, weight loss rate, ascorbic acid (Vc) content, and magnetic resonance imaging (MRI) of the red grapes were recorded every 3 days. The results are as follows: Figure 3 , 4 As shown in Figures 5 and 6.

[0093] The results showed that, compared with unpackaged red grapes (control group) and red grapes packaged in bags prepared using Comparative Examples 1-3, the red grapes packaged in bags prepared using the modified starch-lipid complex base prepared in Examples 1-2 did not show significant changes in appearance or mold growth after 12 days of storage. Furthermore, they exhibited lower weight loss, higher vitamin C content, greater moisture retention, and less pulp deformation. This indicates that under normal temperature and humidity conditions, the modified packaging effectively reduces the loss of moisture and other nutrients in red grapes, inhibits deformation and mold growth, and possesses excellent preservation and anti-mold properties.

[0094] In summary, we choose pea starch with high amylose content and good film-forming property as raw material, and use OSA esterification of starch and non-covalent complex of starch-lipid to synergistically improve the anti-retrogradation and hydrophobicity of starch, and further prepare modified starch-lipid complex film and other packaging materials and isolation materials with excellent performance. The anti-retrogradation performance, surface hydrophobicity, water vapor barrier performance and mechanical properties of the prepared fresh-keeping packaging film and other packaging materials are better than those of traditional natural starch-based film, which can effectively reduce the water loss and other nutrient loss of red plums under normal temperature and humidity conditions, inhibit the deformation and mold change of the appearance of red plums (12d), and has excellent fresh-keeping capacity and mold resistance. The preparation method of the present application is simple, safe and green, the modified starch-lipid complex film has the advantages of edible raw material, environmental friendliness, excellent performance and the like, and the prepared packaging bag has remarkable effect in postharvest preservation of fruits and vegetables, so it has great application prospect in packaging and isolation materials and the like. The above only describes the preferred embodiments of the present application, and is not intended to limit the present application, and any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A modified starch-lipid complex-based film, characterized by: The modified starch is prepared by using pea starch as raw material and octenyl succinic anhydride as modifier.

2. The base film of claim 1, characterized by The XRD diffraction pattern thereof has no strong diffraction peaks at 5°, 17°, 22° and 24°.

3. The base film of claim 1, wherein the base film is prepared by the following steps: S1: mixing starch and water, adding octenyl succinic anhydride for reaction, centrifuging, washing the precipitate, drying, and obtaining modified starch; S2: mixing modified starch and water, adding lipids, heating, then cooling, obtaining paste, drying, grinding, and obtaining modified starch-lipid complex; S3: mixing modified starch-lipid complex, water and glycerol, heating, pouring into a base film mold, and drying to obtain the modified starch-lipid complex base film.

4. The base film of claim 3, characterized by: The lipid in step S2 is an alkyl side chain length selected from C 12 ~ C 18 saturated long chain fatty acid, C 12 ~ C 18 saturated long chain fatty acid monoglyceride, any one or more.

5. The base film of claim 3, characterized by: In step S2, the mass ratio of lipids to modified starch is 1:(20-100).

6. The base film of claim 3, characterized by: In step S3, the mass ratio of modified starch-lipid complex, glycerol and water is 1:0.3:(20-100).

7. The base film of claim 3, wherein step S1 is: mixing starch and water to obtain a starch suspension, esterifying and modifying the starch by dropwise adding octenyl succinic anhydride at a constant temperature, centrifuging, washing the precipitate, drying, and obtaining modified starch.

8. The base film of claim 3, wherein step S2 is: mixing modified starch and water to prepare a 5-15wt% starch suspension, adding lipids, heating for 0.5-5h, cooling, obtaining paste, drying for 2-24h, and grinding to obtain modified starch-lipid complex.

9. The base film of claim 3, wherein step S3 is: mixing modified starch-lipid complex, water and glycerol, stirring and heating at 85-95℃ for 10-120min, pouring into a base film mold, and drying for 2-24h to obtain the modified starch-lipid complex base film.

10. The base film of claim 7, wherein step S1 is: adding 0.75mol / L NaOH solution to a 30-50wt% starch suspension, adjusting the pH to weak alkaline, adding 1-10% octenyl succinic anhydride based on the dry mass of starch at 35℃, stirring at 350rpm for 4h, adding 0.50mol / L HCl to adjust the pH to weak acid, centrifuging, washing the precipitate with water to neutral, and drying at 40℃ for 8-12h to obtain octenyl succinic anhydride modified starch.

11. The base film of claim 10, wherein in step S1, the concentration of the starch suspension is 40%, the amount of octenyl succinic anhydride added is 3-9% based on the dry mass of starch, the weak alkaline pH is 8.0-8.5, and the weak acid pH is 6.

0.

12. The base film of claim 8, wherein step S2 is: mixing modified starch and water to prepare a 5-15wt% starch suspension, then adding lipids, heating at a constant temperature and stirring rate for 1-2h, cooling to 25℃, drying the obtained paste at 40℃ for 6-10h, and grinding to obtain modified starch-lipid complex.

13. The base film of claim 12, wherein in step S2, the heating is carried out at a constant temperature of 90℃ and a stirring rate of 350rpm.

14. The base film of claim 9, wherein step S3: the modified starch-lipid complex, water, and glycerol are mixed, heated and stirred at 85-95°C for 30 min, and then poured into a base film mold and dried for 8-12 h to obtain the base film.

15. Use of the modified starch-lipid complex base film of any one of claims 1-14 in the preparation of packaging materials and isolation materials.

16. The use of claim 15, wherein the packaging material comprises: Food preservation materials, medical packaging bags, and self-sealing bags.

17. The use of claim 15, wherein the barrier material comprises: Disposable tablecloths, ground covers, and greenhouse films.

18. The use of claim 16, wherein the food preservation material comprises: Preservative films, preservative bags, and disposable food bags.

19. Use according to claim 16, characterized in that, Use of the food preservation materials in the preservation of fruits and vegetables, meat, and seafood.

20. The use of claim 16, wherein the medical product packaging bag comprises: Medicine packaging bags, special medical food packaging bags, and health product packaging bags.

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