Photosensitive response type composite fresh-keeping composition, fruit fresh-keeping agent and preparation method of fruit fresh-keeping agent

Abstract

The invention discloses a photosensitive response type composite fresh-keeping composition, a fruit fresh-keeping agent and a preparation method of the photosensitive response type composite fresh-keeping composition, and the photosensitive response type composite fresh-keeping composition comprises the following components in parts by mass: 1-40 parts of shaddock peel extract and 10-60 parts of algal polysaccharide. According to the fruit preservative disclosed by the invention, the natural shaddock peel extract and the algal polysaccharide are used as main components, so that the use of synthetic chemical additives is avoided. Compared with traditional chemical preservatives (such as preservatives and antioxidants), the coating provided by the invention is more environment-friendly, non-toxic and harmless, has no negative influence on human health, and meets the requirements of food safety and environmental protection. The shaddock peel extract is rich in coumarin compounds, the components can be subjected to photosensitive reaction under the irradiation of ultraviolet light or visible light to play antibacterial activity, and a lasting and efficient fresh-keeping effect can be shown in the storage and transportation process.

Description

Technical Field

[0001] The present invention relates to a preservative, in particular to a photosensitivity-responsive composite preservative composition, a fruit preservative and a preparation method thereof. Background Art

[0002] Fruits are rich in nutrients and can provide humans with vitamins, minerals and other nutrients. They are one of people’s main supplementary foods.

[0003] Currently, the main commercial preservation methods are: 1) Physical methods: Cold chain storage and transportation is an ideal and safe storage and transportation method. However, due to its relatively high cost, the conventional market still relies on room temperature storage and transportation. Moreover, cold chain storage and transportation cannot completely control the occurrence of post-harvest diseases, especially those caused by some cold-resistant pathogens such as Downy mildew and Fusarium equisetifolia. Furthermore, the shelf life of fruit at room temperature after cold chain storage and transportation is extremely short, only 1-2 days. 2) Chemical soaking: This method achieves freshness by soaking fruit in agents such as chloramphenicol and prochloraz for 1-5 minutes. These chemicals are both toxic and weakly toxic, and after soaking, they can easily leave residue on the fruit surface, potentially affecting human health. Currently, international fruit storage and preservation mainly relies on a combination of chemical preservation and physical storage technologies. However, as mentioned above, the shelf life of fruit at room temperature after cold chain storage and transportation is extremely short, and chemical materials are involved. Therefore, safely and effectively extending shelf life is a common pursuit. Summary of the Invention

[0004] To address the above-mentioned problems of unsafe fruit preservation and short shelf life, the present invention provides a photosensitive responsive composite fresh-keeping composition, a fruit preservative and a preparation method thereof. The preservative can activate its antibacterial activity under ultraviolet or visible light irradiation, delay the spoilage of fruit, and extend its shelf life at room temperature. It does not contain any chemical agents and is safe and effective.

[0005] In order to achieve the above-mentioned object, the present invention provides a photosensitive responsive composite fresh-keeping composition, which comprises 1-40 parts of pomelo peel extract and 10-60 parts of algae polysaccharide in parts by mass.

[0006] As a natural plant extract, pomelo peel extract is rich in coumarins (such as coumarins and furanocoumarins) as its primary photosensitizing components. Their antimicrobial activity can be activated by UV or visible light irradiation, slowing fruit spoilage. Furthermore, the flavonoids in pomelo peel extract are effective free radical scavengers, exhibiting significant antioxidant activity. Algal polysaccharides (such as sodium alginate and carrageenan) possess excellent moisture retention, film-forming properties, and biodegradability, effectively reducing water evaporation from fruit, delaying oxidation, and exhibiting antimicrobial effects. Furthermore, algal polysaccharides possess natural encapsulation and complexing capabilities. Encapsulating pomelo peel extract effectively prevents degradation or volatilization of coumarin active compounds, prolonging their retention on the fruit surface and improving their sustained release properties. This extends the antimicrobial effect and enhances the fruit's suitability for storage and transportation. The carboxyl or sulfonic acid groups in algal polysaccharides can form complexes with hydroxyl groups, coumarin nuclei, or other polar groups in pomelo peel extract through hydrogen bonding, van der Waals forces, and electrostatic adsorption. At the same time, the hydrophobic components in the pomelo peel extract can be embedded in the microporous structure of the polysaccharide molecules, forming a translucent film on the surface of the fruit, which can slowly release the antibacterial components in the pomelo peel extract under external light stimulation.

[0007] When the ratio of pomelo peel extract to algae polysaccharides is too low, the pomelo peel extract is not fully embedded and evaporates, while a high ratio affects the uniformity of the material. At the optimal ratio, the antibacterial durability and mechanical stability of the plastic wrap are significantly improved.

[0008] Based on this, the present invention proposes a new type of fruit preservative by compounding pomelo peel extract and algae polysaccharides. The preservative is not only antioxidant, but also can actively play an antibacterial role through changes in light, thereby further enhancing the preservation effect.

[0009] Preferably, the invention comprises 15-30 parts of pomelo peel extract and 25-45 parts of algae polysaccharide, calculated by mass.

[0010] Preferably, the algae polysaccharide is one or more of sodium alginate, carrageenan, and xanthophyll polysaccharide.

[0011] Preferably, the preparation method of the pomelo peel extract comprises the following steps: S1. Take fresh pomelo peel, wash and remove impurities from the pulp, cut into small pieces and air-dry; S2. Grind the dried pomelo peel into coarse powder, add 70% ethanol solution with a volume 10-15 times (v / w) of the pomelo peel coarse powder, and reflux extract at 50-60° C. for 1.5-3 hours; S3, collect the filtrate and concentrate it to 1 / 8-1 / 6 of the original volume; S4. Freeze-drying to obtain pomelo peel extract powder.

[0012] The second aspect of the present invention provides a photosensitivity-responsive composite fruit preservative, comprising the above-mentioned photosensitivity-responsive composite preservative composition, wherein the concentration of the pomelo peel extract is 0.05%-2% (w / v), and the concentration of the algae polysaccharide is 0.5%-3% (w / v).

[0013] Specifically, the preservative is evenly applied to the surface of the fruit by spraying, dipping, brushing or rolling.

[0014] The third aspect of the present invention provides a method for preparing the above-mentioned photosensitivity-responsive composite fruit preservative, comprising mixing pomelo peel extract with algae polysaccharide, adding water, and stirring thoroughly to mix.

[0015] Through the above technical solution, the present invention achieves the following beneficial effects: 1. The fruit preservative of this invention uses natural pomelo peel extract and algae polysaccharides as its main ingredients, eliminating the use of synthetic chemical additives. Compared with traditional chemical preservatives (such as preservatives and antioxidants), the coating of this invention is more environmentally friendly, non-toxic, and harmless, with no negative impact on human health, meeting food safety and environmental protection requirements.

[0016] 2. The pomelo peel extract of the present invention is rich in coumarin compounds, which can produce photosensitivity reactions under ultraviolet light or visible light to exert antibacterial activity, and can exhibit a long-lasting and efficient preservation effect during storage and transportation.

[0017] 3. The pomelo peel extract-algae polysaccharide composite fruit preservative of the present invention forms a transparent or translucent protective film during use, preserving the fruit's appearance without affecting its natural flavor. The coumarin compounds in the pomelo peel extract possess a natural aroma without creating a strong odor, ensuring that the appearance and flavor of the fruit are not compromised.

[0018] 4. Algae polysaccharide is used as the matrix material, which has good biodegradability and can be naturally degraded in the environment after use. It meets the requirements of sustainable development and has a lower environmental burden.

[0019] 5. The preparation method of the fruit preservative of the present invention is simple and easy, and can be evenly applied to the surface of the fruit by spraying, dipping, brushing or rolling.

[0020] 6. The photosensitivity-responsive pomelo peel extract-algae polysaccharide composite fruit preservative of the present invention is not only suitable for common fruits (such as cherries, apples, grapes, citrus, strawberries, bananas, mangoes, etc.), but can also be extended to the preservation of other fruits and vegetables, and has broad market application prospects. DETAILED DESCRIPTION

[0021] The following is a detailed description of the specific embodiments of the present invention in conjunction with the examples. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention and are not intended to limit the present invention.

[0022] Example 1 The preparation method of the photosensitivity-responsive pomelo peel extract-algae polysaccharide composite fruit preservative is as follows: The preparation method of grapefruit peel extract is as follows: S1. Take fresh pomelo peel, wash and remove impurities from the pulp, cut into small pieces and air-dry; S2. Grind the dried pomelo peel into coarse powder, add 70% ethanol solution with a volume 10 times (v / w) of the pomelo peel coarse powder, and reflux extract at 60°C for 1.5 hours; S3, collect the filtrate and concentrate it to 1 / 8 of the original volume; S4. Using freeze-drying method to obtain grapefruit peel extract powder.

[0023] Mix the pomelo peel extract and sodium alginate, add appropriate amount of water to make the concentration of pomelo peel extract 0.05% (w / v) and the concentration of sodium alginate 0.5% (w / v), and stir thoroughly to mix.

[0024] Example 2 The preparation method of the photosensitivity-responsive pomelo peel extract-algae polysaccharide composite fruit preservative is as follows: The preparation method of grapefruit peel extract is as follows: S1. Take fresh pomelo peel, wash and remove impurities from the pulp, cut into small pieces and air-dry; S2. Grind the dried pomelo peel into coarse powder, add 70% ethanol solution with a volume 15 times (v / w) of the pomelo peel coarse powder, and reflux extract at 50° C. for 3 hours; S3, collect the filtrate and concentrate it to 1 / 6 of the original volume; S4. Using freeze-drying method to obtain grapefruit peel extract powder.

[0025] Mix the pomelo peel extract and sodium alginate, add appropriate amount of water to make the concentration of pomelo peel extract 0.5% (w / v) and the concentration of sodium alginate 1.5% (w / v), and stir thoroughly to mix.

[0026] Example 3 The preparation method of the photosensitivity-responsive pomelo peel extract-algae polysaccharide composite fruit preservative is as follows: The preparation method of grapefruit peel extract is as follows: S1. Take fresh pomelo peel, wash and remove impurities from the pulp, cut into small pieces and air-dry; S2. Grind the dried pomelo peel into coarse powder, add 70% ethanol solution with a volume 12 times (v / w) of the pomelo peel coarse powder, and reflux extract at 55°C for 2 hours; S3, collect the filtrate and concentrate it to 1 / 7 of the original volume; S4. Using freeze-drying method to obtain grapefruit peel extract powder.

[0027] Mix the pomelo peel extract, carrageenan, and xanthophyll polysaccharide, add appropriate amount of water to make the concentration of pomelo peel extract 1.5% (w / v), carrageenan concentration 1% (w / v), and xanthophyll polysaccharide concentration 1.5% (w / v), and stir thoroughly to mix.

[0028] Example 4 The preparation method of the photosensitivity-responsive pomelo peel extract-algae polysaccharide composite fruit preservative is as follows: The preparation method of grapefruit peel extract is as follows: S1. Take fresh pomelo peel, wash and remove impurities from the pulp, cut into small pieces and air-dry; S2. Grind the dried pomelo peel into coarse powder, add 70% ethanol solution with a volume 10 times (v / w) of the pomelo peel coarse powder, and reflux extract at 60°C for 1.5 hours; S3, collect the filtrate and concentrate it to 1 / 8 of the original volume; S4. Using freeze-drying method to obtain grapefruit peel extract powder.

[0029] Mix the grapefruit peel extract and the yellow algae polysaccharide, add appropriate amount of water to make the concentration of the grapefruit peel extract 2% (w / v) and the yellow algae polysaccharide concentration 3% (w / v), and stir thoroughly to mix.

[0030] Comparative Example 1 Other conditions were the same as in Example 1, except that the grapefruit peel extract was omitted.

[0031] Comparative Example 2 Other conditions were the same as in Example 1, except that sodium alginate was omitted.

[0032] Comparative Example 3 Other conditions were the same as in Example 1, except that the grapefruit peel extract was omitted and the sodium alginate concentration was 0.55% (w / v).

[0033] Comparative Example 4 Other conditions were the same as in Example 1, except that sodium alginate was omitted and the concentration of grapefruit peel extract was 0.55% (w / v).

[0034] Comparative Example 5 Other conditions were the same as in Example 1, except that the concentration of the pomelo peel extract was 0.03% (w / v).

[0035] Comparative Example 6 Other conditions were the same as in Example 1, except that the concentration of the pomelo peel extract was 3% (w / v).

[0036] Comparative Example 7 Other conditions were the same as in Example 1, except that the concentration of sodium alginate was 0.3% (w / v).

[0037] Comparative Example 8 Other conditions were the same as in Example 1, except that the concentration of sodium alginate was 4% (w / v).

[0038] Performance Testing Cherries of the same variety, without mechanical damage, mold or rot were selected and divided into 18 groups. Group 1 was not treated (control group); Group 2 was soaked in clean water for 30 seconds, placed in a sealed fresh-keeping box, drained in a ventilated place, and placed in a dark environment at room temperature (25°C) for 30 minutes; Groups 3-14 were soaked in the fruit preservatives prepared in the above examples and comparative examples for 30 seconds, placed in a sealed fresh-keeping box, drained in a ventilated place, and irradiated with visible light for 30 minutes at room temperature (25°C); Groups 15-18 were soaked in the fruit preservatives prepared in the above examples for 30 seconds, placed in a sealed fresh-keeping box, drained in a ventilated place, and placed in a dark environment at room temperature (25°C) for 30 minutes.

[0039] Afterwards, each group of cherries was stored at a low temperature (4°C) without being protected from light. Cherries were regularly tested for moldiness, weight loss, and hardness. The results are shown in Table 1.

[0040] Table 1 Mold rate, weight loss rate and hardness data of cherries in each group after 15 days

[0041] Comprehensive data on mold rate, weight loss, and hardness across the groups show that Examples 1-4 demonstrated excellent overall freshness preservation performance throughout the storage period, with low mold rates, minimal weight loss, and excellent hardness retention, significantly delaying fruit decay, water evaporation, and texture degradation. Comparative Examples 1-2, containing only a single active ingredient (grapefruit peel extract or algae polysaccharide), exhibited limited freshness preservation, with high mold rates, weight loss rates, and significant hardness variation. This suggests that the synergistic use of grapefruit peel extract and algae polysaccharide is required for their effective performance. Comparative Examples 3 and 4 (0.55% sodium alginate or grapefruit peel extract) exhibited superior freshness preservation performance to Comparative Examples 1-2, with slightly reduced mold rates and weight loss rates, and slightly improved hardness retention, but still inferior to that of the Example groups. This demonstrates that even increasing the concentration of a single component is difficult to achieve the same preservation performance as a combined system, and that the construction of a composite membrane structure is key to improving freshness preservation performance. Comparative Examples 5-8 demonstrated moderate freshness preservation performance. Although there is a certain improvement compared with Comparative Examples 1 and 2, it is not as good as the Example Group in terms of mildew resistance, delayed water loss and hardness retention. This shows that although adjusting the concentration of a single component can improve some properties, the overall functionality of the plastic wrap is still limited when a complete composite network structure is not formed.

[0042] In summary, the present invention combines the photosensitivity-responsive coumarins from pomelo peel extract with algal polysaccharides to develop a natural, green, and highly effective fruit preservative. This fruit preservative is not only environmentally friendly and safe, but also, through activation by ultraviolet or visible light, achieves a long-lasting antibacterial effect, significantly extending the shelf life of fruit and reducing food waste, thus possessing broad application prospects. Therefore, the present invention offers significant technical advantages and socioeconomic benefits in the field of fruit preservation.

[0043] The preferred embodiments of the present invention are described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the scope of protection of the present invention.

[0044] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any appropriate manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0045] In addition, the various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. A photosensitivity-responsive composite fresh-keeping composition, characterized in that: Calculated by mass, it comprises 1-40 parts of pomelo peel extract and 10-60 parts of algae polysaccharide.

2. The photosensitive responsive composite fresh-keeping composition according to claim 1, characterized in that: Calculated by weight, the invention comprises 10-30 parts of pomelo peel extract and 30-50 parts of algae polysaccharide.

3. The photosensitive responsive composite fresh-keeping composition according to claim 1 or 2, characterized in that: The algae polysaccharide is one or more of sodium alginate, carrageenan, and xanthophyll polysaccharide.

4. The photosensitive responsive composite fresh-keeping composition according to claim 1 or 2, characterized in that: The preparation method of the pomelo peel extract comprises the following steps: S1. Take fresh pomelo peel, wash and remove impurities from the pulp, cut into small pieces and air-dry; S2. Grind the dried pomelo peel into coarse powder, add 70% ethanol solution with a volume 10-15 times the mass of the pomelo peel coarse powder, and reflux extract at 50-60° C. for 1.5-3 hours; S3, collect the filtrate and concentrate it to 1 / 8-1 / 6 of the original volume; S4. Freeze-drying to obtain pomelo peel extract powder.

5. A photosensitivity-responsive composite fruit preservative, characterized in that: The photosensitive responsive composite fresh-keeping composition comprises the photosensitive responsive composite fresh-keeping composition according to any one of claims 1 to 4, wherein the concentration of the pomelo peel extract is 0.05%-2% (w / v), and the concentration of the algae polysaccharide is 0.5%-3% (w / v).

6. The photosensitivity-responsive composite fruit preservative according to claim 5, characterized in that: The preservative is evenly coated on the surface of the fruit by spraying, dipping, brushing or rolling.

7. The method for preparing the photosensitivity-responsive composite fruit preservative according to claim 5 or 6, characterized in that: Mix the pomelo peel extract and algae polysaccharide, add water, and stir thoroughly to mix.

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