A compound preserved fruit and a method for preparing the same

Abstract

The application discloses a compound preserved fruit and a preparation method thereof. The preparation raw materials are apricots and rowan berries, and the mass ratio of the apricots to the rowan berries is (1-3):1. The compound preserved fruit prepared by using the apricots and the rowan berries as the compound preparation raw materials is influenced by a color protection liquid and sugar impregnation, browning of the apricots and the rowan berries is reduced, and the prepared product is bright and attractive in color. The mushroom polysaccharide and the sargassum fusiforme polysaccharide are added into a sugar liquid for impregnation, and the phenomenon of sand returning or sugar flowing of the preserved fruit is effectively reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of food processing and storage, and particularly relates to a composite preserved fruit and a preparation method thereof. Background Art

[0002] Preserved fruit is a food product made from fresh fruit through a series of processes, including peeling, pitting, candiing, soaking, and drying. It is bright and transparent, with a dry, slightly sticky surface and a moisture content below 30%. Preserved fruit comes in a wide variety, with well-known traditional products including apple preserves, tamarind preserves, apricot preserves, pear preserves, peach preserves, Taiping fruit preserves, green plums, hawthorn slices, and fruit leather. After fresh fruit is washed and pitted, some of the flesh is exposed to air. The oxygen in the air quickly activates polyphenol oxidase in the flesh, oxidizing polyphenols to quinones, resulting in browning (enzymatic browning). Furthermore, during the candiing process, amino compounds in the preserved fruit react with reducing sugars to produce the Maillard reaction, leading to browning (non-enzymatic browning). Adding chemical inhibitors, applying edible coatings, or antioxidants such as ascorbic acid and sulfites can be toxic if used in excessive amounts. Currently, there are no reports on reducing browning by combining different fruits in the preparation of preserved fruit.

[0003] Sucrose is the most commonly used syrup in preserved fruit production, but it has a strong tendency to crystallize, making it very easy for crystal particles to form on the surface or inside the finished preserved fruit, resulting in grit or sugar runoff, which can make the preserved fruit taste coarse and reduce its appearance quality. Sucrose partially converts during the maceration and drying processes. Low invert sugar levels can cause grit, while excessive levels can cause sugar runoff. Various techniques for controlling invert sugar levels, such as controlling drying temperature, are unstable and cannot completely solve the problem. Adding a small amount of maltose can partially solve the problem, but it can also make the surface of the preserved fruit sticky, making it sticky and inconvenient to eat. Summary of the Invention

[0004] The purpose of the present invention is to provide a composite preserved fruit and a preparation method thereof.

[0005] A composite preserved fruit is prepared from apricot and crab apple in a mass ratio of (1-3):1.

[0006] The preparation method of the composite preserved fruit is carried out according to the following steps:

[0007] (1) Wash, peel, and pit apricots and crab apples, then slice them. Mix the apricot slices and crab apple slices in a mass ratio of (1-3):1 to make mixed fruit slices.

[0008] (2) Soak the mixed fruit slices in color-protecting solution for 1-3 hours, place them in an ultrasonic oscillator for 10-15 minutes, remove them, rinse with water, and drain;

[0009] (3) Immersing the concentrated soaked mixed fruit slices in sugar solution, subjecting them to pulse electric field treatment at room temperature, and continuing to soak for 2-5 hours after pulse treatment, and then taking them out and draining them;

[0010] (4) Drying the mixed fruit slices from which the sugar solution has been drained to obtain preserved fruit.

[0011] The mass fractions of the components in the color protecting liquid are: 0.1-0.3% of citric acid, 0.1-0.3% of vitamin C, 0.3-0.8% of CaCl2, 0.8-1.5% of NaCl, and the balance is water.

[0012] The power of the ultrasonic oscillator in step (2) is 150-200W.

[0013] The pulse electric field intensity of the pulse electric field treatment in step (3) is 5-10 kV / cm, the pulse width is 50-150 μs, the constant pulse frequency is 50-80 Hz, and the pulse number ranges from 400-800.

[0014] The mass fractions of the components in the sugar solution are: 20-40% sucrose, 5-10% lentinan, 5-10% sargassum polysaccharide, and the balance is water.

[0015] The molecular weight of the lentinan is 40-70 kDa.

[0016] The Sargassum fusiformis polysaccharide is prepared by the following method (referring to the method disclosed in CN 115433290 A): taking Sargassum fusiformis and drying it at 40-60°C, crushing it with a grinder at room temperature, and then passing it through a 30-60 mesh sieve, then immersing the Sargassum fusiformis powder in 95% ethanol for 20-28 hours, then setting the ratio of defatted Sargassum fusiformis powder to deionized water to 30-50 g / L, adjusting the pH of the suspension to 9-11, adding 0.9% alkaline protease, extracting at 40-60°C for 3-5 hours, inactivating the mixture for 8-12 minutes and centrifuging it at 2500-3500g for 8-12 minutes; concentrating the extract and precipitating it with ethanol to a final concentration of 60%; washing the precipitate collected by centrifugation with 95% ethanol, then dissolving it with deionized water, and finally freeze-drying it to obtain the Sargassum fusiformis polysaccharide.

[0017] The drying temperature in step (4) is 50-70° C., and the drying is performed until the moisture content is 15-25%.

[0018] The beneficial effects of the present invention are as follows: the composite preserved fruit of the present invention adopts apricot and sand apple as composite preparation raw materials, and under the influence of color protection liquid and sugar soaking, the browning of each is reduced, so that the prepared product has bright and attractive color; Lentinan and Sargassum fusiforme polysaccharide are added to the sugar solution for soaking, which effectively reduces the sand return or sugar flow phenomenon of the preserved fruit. DETAILED DESCRIPTION

[0019] To facilitate understanding of the present invention, the present invention will be described more fully below. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0020] The lentinan used in the following examples was purchased from Shaanxi Kangjun Biotechnology Co., Ltd.

[0021] Example 1

[0022] A composite preserved fruit is prepared from apricots and crab apples in a mass ratio of 2:1.

[0023] The preparation method of the composite preserved fruit is carried out according to the following steps:

[0024] (1) Wash, peel, and pit apricots and crab apples, then slice them. Mix the apricot slices and crab apple slices in a mass ratio of 2:1 to make mixed fruit slices.

[0025] (2) Soak the mixed fruit slices in a color-protecting solution for 2 h, place them in an ultrasonic oscillator (power 180 W) for 12 min, remove them, rinse with water, and drain. The mass fractions of the components in the color-protecting solution are as follows: 0.2% citric acid, 0.2% vitamin C, 0.6% CaCl2, 1.2% NaCl, and the balance water.

[0026] (3) Immersing the mixed fruit slices after concentrated soaking in sugar solution, performing pulse electric field treatment at room temperature, continuing to soak for 4 hours after pulse treatment, and then taking out and draining; the pulse electric field intensity of the pulse electric field treatment is 8 kV / cm, the pulse width is 100 μs, the constant pulse frequency is 60 Hz, and the number of pulses is 600; the mass fractions of the components in the sugar solution are: 30% sucrose, 8% lentinan, 8% sargassum polysaccharide, and the balance is water; the molecular weight of the lentinan is 60 kDa;

[0027] The Sargassum fusiformis polysaccharide is prepared by the following method: drying Sargassum fusiformis at 50°C, crushing it with a grinder at room temperature, and then passing it through a 50-mesh sieve. Then, the Sargassum fusiformis powder is immersed in 95% ethanol for 24 hours. Then, the ratio of defatted Sargassum fusiformis powder to deionized water is set to 40g / L, the pH of the suspension is adjusted to 10, 0.9% alkaline protease is added, and extraction is carried out at 50°C for 4 hours. The mixture is inactivated for 10 minutes and centrifuged at 3000g for 10 minutes; the concentrated extract is precipitated with ethanol to a final concentration of 60%; the precipitate collected by centrifugation is washed with 95% ethanol, then dissolved with deionized water, and finally freeze-dried to obtain the Sargassum fusiformis polysaccharide.

[0028] (4) Drying the mixed fruit slices from which the sugar solution has been drained to obtain preserved fruit; the drying temperature is 60° C., and ...

[0029] Example 2

[0030] A composite preserved fruit is prepared from apricot and crab apple, wherein the mass ratio of the apricot to the crab apple is 1:1.

[0031] The preparation method of the composite preserved fruit is carried out according to the following steps:

[0032] (1) Wash, peel, and pit apricots and crab apples, then slice them. Mix the apricot slices and crab apple slices in a mass ratio of 1:1 to make mixed fruit slices.

[0033] (2) Soak the mixed fruit slices in a color-protecting solution for 1 hour, place them in an ultrasonic oscillator (power: 150W) for 10 minutes, remove them, rinse with water, and drain. The mass fractions of the components in the color-protecting solution are: 0.1% citric acid, 0.1% vitamin C, 0.3% CaCl2, 0.8% NaCl, and the balance is water.

[0034] (3) Immersing the concentrated soaked mixed fruit slices in a sugar solution, subjecting them to a pulsed electric field treatment at room temperature, continuing to soak for 2 hours after the pulse treatment, and then taking them out and draining them; the pulsed electric field intensity of the pulsed electric field treatment is 5 kV / cm, the pulse width is 50 μs, the constant pulse frequency is 50 Hz, and the number of pulses is 400; the mass fractions of the components in the sugar solution are: sucrose 20%, lentinan 5%, and hijiki polysaccharide 5%, with the remainder being water; the molecular weight of the lentinan is 50 kDa;

[0035] The Sargassum fusiformis polysaccharide is prepared by the following method: drying the Sargassum fusiformis at 40°C, crushing it with a grinder at room temperature and passing it through a 40-mesh sieve, then immersing the Sargassum fusiformis powder in 95% ethanol for 20 hours, then setting the ratio of defatted Sargassum fusiformis powder to deionized water to 30g / L, adjusting the pH of the suspension to 9, adding 0.9% alkaline protease, extracting at 40°C for 5 hours, inactivating the mixture for 12 minutes and centrifuging it at 2500g for 12 minutes; concentrating the extract and precipitating it with ethanol to a final concentration of 60%; washing the precipitate collected by centrifugation with 95% ethanol, then dissolving it with deionized water, and finally freeze-drying it to obtain the Sargassum fusiformis polysaccharide.

[0036] (4) Drying the mixed fruit slices from which the sugar solution has been drained to obtain preserved fruit; the drying temperature is 50° C., and ...

[0037] Example 3

[0038] A composite preserved fruit is prepared from apricot and crab apple, wherein the mass ratio of the apricot to the crab apple is 3:1.

[0039] The preparation method of the composite preserved fruit is carried out according to the following steps:

[0040] (1) Wash, peel, and pit apricots and crab apples, then slice them. Mix the apricot slices and crab apple slices in a mass ratio of 3:1 to make mixed fruit slices.

[0041] (2) Soak the mixed fruit slices in a color-protecting solution for 3 h, place them in an ultrasonic oscillator (power: 200 W) for 10 min, remove them, rinse with water, and drain. The color-protecting solution contains the following components by mass: 0.3% citric acid, 0.3% vitamin C, 0.8% CaCl2, 1.5% NaCl, and the balance is water.

[0042] (3) Immersing the mixed fruit slices after concentrated soaking in sugar solution, performing pulse electric field treatment at room temperature, continuing to soak for 5 hours after pulse treatment, and then taking them out and draining them; the pulse electric field intensity of the pulse electric field treatment is 10 kV / cm, the pulse width is 150 μs, the constant pulse frequency is 80 Hz, and the number of pulses is 800; the mass fractions of the components in the sugar solution are: sucrose 40%, lentinan 10%, and sea lettuce polysaccharide 10%, and the balance is water; the molecular weight of the lentinan is 70 kDa;

[0043] The Sargassum fusiformis polysaccharide is prepared by the following method: drying Sargassum fusiformis at 60°C, crushing it with a grinder at room temperature and then passing it through a 60-mesh sieve, then immersing the Sargassum fusiformis powder in 95% ethanol for 28 hours, then setting the ratio of defatted Sargassum fusiformis powder to deionized water to 50g / L, adjusting the pH of the suspension to 11, adding 0.9% alkaline protease, extracting at 60°C for 3 hours, inactivating the mixture for 8 minutes and centrifuging it at 3500g for 8 minutes; concentrating the extract and precipitating it with ethanol to a final concentration of 60%; washing the precipitate collected by centrifugation with 95% ethanol, then dissolving it with deionized water, and finally freeze-drying it to obtain the Sargassum fusiformis polysaccharide.

[0044] (4) Drying the mixed fruit slices from which the sugar solution has been drained to obtain preserved fruit; the drying temperature is 70° C., and ...

[0045] Comparative Example 1

[0046] A method for preparing preserved fruit is carried out according to the following steps:

[0047] (1) Wash, peel, and pit the apricots, and then slice them into slices;

[0048] (2) Soak the fruit slices in a color-protecting solution for 2 h, place them in an ultrasonic oscillator (power 180 W) for 12 min, remove them, rinse with water, and drain. The mass fractions of the components in the color-protecting solution are as follows: 0.2% citric acid, 0.2% vitamin C, 0.6% CaCl2, 1.2% NaCl, and the balance water.

[0049] (3) Immersing the concentrated soaked fruit slices in a sugar solution, subjecting them to a pulsed electric field treatment at room temperature, continuing to soak for 4 hours, and then taking them out and draining them; the pulsed electric field intensity of the pulsed electric field treatment is 8 kV / cm, the pulse width is 100 μs, the constant pulse frequency is 60 Hz, and the number of pulses is 600; the mass fractions of the components in the sugar solution are: 30% sucrose, 8% lentinan, 8% sargassum polysaccharide, and the balance is water; the molecular weight of the lentinan is 60 kDa;

[0050] The Sargassum fusiformis polysaccharide is prepared by the following method: drying Sargassum fusiformis at 50°C, crushing it with a grinder at room temperature, and then passing it through a 50-mesh sieve. Then, the Sargassum fusiformis powder is immersed in 95% ethanol for 24 hours. Then, the ratio of defatted Sargassum fusiformis powder to deionized water is set to 40g / L, the pH of the suspension is adjusted to 10, 0.9% alkaline protease is added, and extraction is carried out at 50°C for 4 hours. The mixture is inactivated for 10 minutes and centrifuged at 3000g for 10 minutes; the concentrated extract is precipitated with ethanol to a final concentration of 60%; the precipitate collected by centrifugation is washed with 95% ethanol, then dissolved with deionized water, and finally freeze-dried to obtain the Sargassum fusiformis polysaccharide.

[0051] (4) Drying the fruit slices after draining the sugar solution to obtain preserved fruit; the drying temperature is 60° C., and ...

[0052] Comparative Example 2

[0053] A method for preparing preserved fruit is carried out according to the following steps:

[0054] (1) Wash, peel, and core the crab apples and slice them into slices;

[0055] (2) Soak the fruit slices in a color-protecting solution for 2 h, place them in an ultrasonic oscillator (power 180 W) for 12 min, remove them, rinse with water, and drain. The mass fractions of the components in the color-protecting solution are as follows: 0.2% citric acid, 0.2% vitamin C, 0.6% CaCl2, 1.2% NaCl, and the balance water.

[0056] (3) Immersing the concentrated soaked fruit slices in a sugar solution, subjecting them to a pulsed electric field treatment at room temperature, continuing to soak for 4 hours, and then taking them out and draining them; the pulsed electric field intensity of the pulsed electric field treatment is 8 kV / cm, the pulse width is 100 μs, the constant pulse frequency is 60 Hz, and the number of pulses is 600; the mass fractions of the components in the sugar solution are: 30% sucrose, 8% lentinan, 8% sargassum polysaccharide, and the balance is water; the molecular weight of the lentinan is 60 kDa;

[0057] The Sargassum fusiformis polysaccharide is prepared by the following method: drying Sargassum fusiformis at 50°C, crushing it with a grinder at room temperature, and then passing it through a 50-mesh sieve. Then, the Sargassum fusiformis powder is immersed in 95% ethanol for 24 hours. Then, the ratio of defatted Sargassum fusiformis powder to deionized water is set to 40g / L, the pH of the suspension is adjusted to 10, 0.9% alkaline protease is added, and extraction is carried out at 50°C for 4 hours. The mixture is inactivated for 10 minutes and centrifuged at 3000g for 10 minutes; the concentrated extract is precipitated with ethanol to a final concentration of 60%; the precipitate collected by centrifugation is washed with 95% ethanol, then dissolved with deionized water, and finally freeze-dried to obtain the Sargassum fusiformis polysaccharide.

[0058] (4) Drying the fruit slices after draining the sugar solution to obtain preserved fruit; the drying temperature is 60° C., and ...

[0059] Comparative Example 3

[0060] A composite preserved fruit is prepared from apricots and crab apples in a mass ratio of 2:1.

[0061] The preparation method of the composite preserved fruit is carried out according to the following steps:

[0062] (1) Wash, peel, and pit apricots and crab apples, then slice them. Mix the apricot slices and crab apple slices in a mass ratio of 2:1 to make mixed fruit slices.

[0063] (2) Soak the mixed fruit slices in a color-protecting solution for 2 h, place them in an ultrasonic oscillator (power 180 W) for 12 min, remove them, rinse with water, and drain. The mass fractions of the components in the color-protecting solution are as follows: 0.2% citric acid, 0.2% vitamin C, 0.6% CaCl2, 1.2% NaCl, and the balance water.

[0064] (3) Immersing the concentrated soaked mixed fruit slices in a sugar solution, subjecting them to a pulsed electric field treatment at room temperature, continuing to soak for 4 hours, and then removing and draining; the pulsed electric field intensity of the pulsed electric field treatment is 8 kV / cm, the pulse width is 100 μs, the constant pulse frequency is 60 Hz, and the number of pulses is 600; the mass fractions of the components in the sugar solution are: 30% sucrose, 16% lentinan, and the balance is water; the molecular weight of the lentinan is 60 kDa;

[0065] (4) Drying the mixed fruit slices from which the sugar solution has been drained to obtain preserved fruit; the drying temperature is 60° C., and ...

[0066] Comparative Example 4

[0067] A composite preserved fruit is prepared from apricots and crab apples in a mass ratio of 2:1.

[0068] The preparation method of the composite preserved fruit is carried out according to the following steps:

[0069] (1) Wash, peel, and pit apricots and crab apples, then slice them. Mix the apricot slices and crab apple slices in a mass ratio of 2:1 to make mixed fruit slices.

[0070] (2) Soak the mixed fruit slices in a color-protecting solution for 2 h, place them in an ultrasonic oscillator (power 180 W) for 12 min, remove them, rinse with water, and drain. The mass fractions of the components in the color-protecting solution are as follows: 0.2% citric acid, 0.2% vitamin C, 0.6% CaCl2, 1.2% NaCl, and the balance water.

[0071] (3) Immersing the concentrated soaked mixed fruit slices in a sugar solution, subjecting them to pulse electric field treatment at room temperature, continuing to soak for 4 hours after the pulse treatment, and then taking them out and draining them; the pulse electric field intensity of the pulse electric field treatment is 8 kV / cm, the pulse width is 100 μs, the constant pulse frequency is 60 Hz, and the number of pulses is 600; the mass fractions of the components in the sugar solution are: 30% sucrose, 16% Sargassum fusiformis polysaccharide, and the balance is water;

[0072] The Sargassum fusiformis polysaccharide is prepared by the following method: drying Sargassum fusiformis at 50°C, crushing it with a grinder at room temperature, and then passing it through a 50-mesh sieve. Then, the Sargassum fusiformis powder is immersed in 95% ethanol for 24 hours. Then, the ratio of defatted Sargassum fusiformis powder to deionized water is set to 40g / L, the pH of the suspension is adjusted to 10, 0.9% alkaline protease is added, and extraction is carried out at 50°C for 4 hours. The mixture is inactivated for 10 minutes and centrifuged at 3000g for 10 minutes; the concentrated extract is precipitated with ethanol to a final concentration of 60%; the precipitate collected by centrifugation is washed with 95% ethanol, then dissolved with deionized water, and finally freeze-dried to obtain the Sargassum fusiformis polysaccharide.

[0073] (4) Drying the mixed fruit slices from which the sugar solution has been drained to obtain preserved fruit; the drying temperature is 60° C., and ...

[0074] Experimental example:

[0075] The relative browning degrees of Examples 1-3 and Comparative Examples 1-2 at 420 nm were measured using a spectrophotometer. During the measurement, apricot preserves and sand fruit preserves were separated from the composite preserved fruits prepared in Examples 1-3, and the relative browning degrees were measured separately. The average value was then taken as the relative browning degree of the composite preserved fruits.

[0076] Each group of experiments was repeated 5 times, and the average value was taken. SPSS 24.0 software was used for statistical analysis. The data were expressed as mean ± standard deviation. The Kolmogorov-Smirnov test was used to test the normality of the data. For data that met the normal distribution, the t-test was used to compare the mean differences between the two groups. The difference was considered statistically significant when P < 0.05.

[0077] The measurement results are shown in Table 1:

[0078] Table 1

[0079]

[0080] Note: * represents P < 0.05 compared with Example 1.

[0081] The preserved fruits prepared in Examples 1-3 and Comparative Examples 3-4 were dried and stored at a temperature of 25° C. and a relative humidity of 65% for 30 days, and the quality of the finished products was observed. 1 kg of the preserved fruits were weighed, and the surface and interior of the preserved fruits were observed using a magnifying glass and a polarizing microscope, respectively. Preserved fruits with easily visible crystals (diameter greater than 200 μm) accumulated on the surface were designated as surface crystallized preserved fruits, and preserved fruits with easily visible crystals accumulated inside were designated as internal crystallized preserved fruits. The crystallization rates of the surface and interior of the finished products were calculated according to the following formula:

[0082] Surface crystallization rate = total mass of all surface crystallized preserved fruits / total mass of all preserved fruits × 100%;

[0083] Internal crystallization rate = total mass of all internally crystallized preserved fruits / total mass of all preserved fruits × 100%;

[0084] All measurements were repeated 5 times and the average value was taken. The results are shown in Table 2:

[0085] Table 2

[0086]

[0087] Note: * represents P < 0.05 compared with Example 1.

[0088] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the patent for this invention shall be determined by the appended claims.

Claims

1. A composite preserved fruit, characterized in that: The raw materials for the preparation are apricot and crab apple, and the mass ratio of apricot and crab apple is (1-3):1; The preparation method of the composite preserved fruit is characterized by being carried out according to the following steps: (1) Wash, peel, and pit apricots and crab apples, then slice them. Mix the apricot slices and crab apple slices in a mass ratio of (1-3):1 to make mixed fruit slices. (2) Soak the mixed fruit slices in color-protecting solution for 1-3 hours, place them in an ultrasonic oscillator for 10-15 minutes, remove them, rinse with water, and drain; The mass fractions of the components in the color protection solution are: citric acid 0.1-0.3%, vitamin C 0.1-0.3%, CaCl2 0.3-0.8%, NaCl 0.8-1.5%, and the balance is water; (3) Immerse the mixed fruit slices after concentrated soaking in sugar solution and perform pulse electric field treatment at room temperature. After pulse treatment, continue soaking for 2-5 hours, then take out and drain; The mass fractions of the components in the sugar solution are: sucrose 20-40%, lentinan 5-10%, sargassum fusiformis polysaccharide 5-10%, and the balance is water; (4) Drying the mixed fruit slices from which the sugar solution has been drained to obtain preserved fruit.

2. The method for preparing the composite preserved fruit according to claim 1, wherein The power of the ultrasonic oscillator in step (2) is 150-200W.

3. The method for preparing the composite preserved fruit according to claim 1, wherein The pulse electric field intensity of the pulse electric field treatment in step (3) is 5-10 kV / cm, the pulse width is 50-150 μs, the constant pulse frequency is 50-80 Hz, and the pulse number ranges from 400-800.

4. The method for preparing the composite preserved fruit according to claim 1, wherein The molecular weight of the lentinan is 40-70 kDa.

5. The method for preparing the composite preserved fruit according to claim 1, wherein The Sargassum fusiformis polysaccharide is prepared by the following method: drying Sargassum fusiformis at 40-60°C, crushing it with a grinder at room temperature, and then passing it through a 30-60 mesh sieve, then immersing the Sargassum fusiformis powder in 95% ethanol for 20-28 hours, then setting the ratio of defatted Sargassum fusiformis powder to deionized water to 30-50 g / L, adjusting the pH of the suspension to 9-11, adding 0.9% alkaline protease, extracting at 40-60°C for 3-5 hours, inactivating the mixture for 8-12 minutes, and centrifuging it at 2500-3500g for 8-12 minutes; concentrating the extract and precipitating it with ethanol to a final concentration of 60%; washing the precipitate collected by centrifugation with 95% ethanol, then dissolving it with deionized water, and finally freeze-drying it to obtain the Sargassum fusiformis polysaccharide.

6. The method for preparing the composite preserved fruit according to claim 1, wherein: The drying temperature in step (4) is 50-70°C, and the drying is performed to a moisture content of 15-25%.

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