Low-sugar jelly and preparation method thereof

Abstract

The invention relates to the technical field of food processing, in particular to low-sugar jelly and a preparation method thereof, and the preparation method comprises the following steps: carrying out acidolysis treatment on pretreated passion fruit peel and extracting filtrate; boiling and concentrating the filtrate, adjusting the pH value of the concentrated solution to 9.0-11.0, and then degreasing in a constant-temperature water bath at the temperature of 10-25 DEG C for 1-3 hours to obtain a degreased solution; adding ethanol into the degreased solution for precipitation to obtain a precipitate, and cleaning and drying the precipitate to obtain low-methoxyl pectin; and uniformly stirring the low-methoxyl pectin, a calcium source, an acidulant and water to obtain the passion fruit low-sugar jelly. The raw materials are innovative, and waste is turned into wealth; according to the invention, high-ester pectin in passion fruit peel is successfully converted into low-ester pectin, the dependence of traditional jelly on high sugar degree is broken, and the product can be gelled under a sugar-free condition and accords with a healthy diet trend. The obtained jelly is moderate in gel strength and smooth in taste.

Description

Technical Field

[0001] This invention relates to the field of food processing technology, and in particular to a low-sugar jelly and its preparation method. Background Technology

[0002] The rapid development of the passion fruit juice beverage industry has generated a large amount of by-products, namely, passion fruit peels. Currently, a small amount of passion fruit peels is discarded or used as animal feed, while the majority is not effectively utilized, resulting in resource waste and environmental pressure. Passion fruit peels are rich in pectin, but their natural form is high-ester pectin. Making traditional jellies requires adding large amounts of sucrose (usually above 60%) to form a gel, which does not meet the modern consumer demand for low-sugar, healthy foods.

[0003] Low-methoxyl pectin can form gels via calcium ions under low-sugar conditions, making it an ideal raw material for producing low-sugar or sugar-free gel foods. Currently, commercially available low-methoxyl pectin is mostly extracted from citrus peels and apple pomace, and is produced through acidification or amidation methods, resulting in high costs. However, there are no systematic reports or patent protection regarding the technology of using passion fruit peels, particularly through alkali modification to prepare low-methoxyl pectin and directly using it in the production of low-sugar jellies.

[0004] In summary, existing technologies suffer from problems such as raw material waste, high sugar content in products, or reliance on expensive raw materials.

[0005] Therefore, existing technologies need to be improved. Summary of the Invention

[0006] In view of the shortcomings of the prior art, the purpose of this invention is to provide a low-sugar jelly and its preparation method, which aims to solve the problems of raw material waste, high sugar content of products, or reliance on expensive raw materials in the prior art.

[0007] The technical solution of the present invention is as follows: In a first aspect, the present invention provides a method for preparing low-sugar jelly, comprising the following steps: S1. The pretreated passion fruit peel is acid-hydrolyzed and the filtrate is extracted. S2. Boil and concentrate the filtrate to obtain a concentrated solution; S3. Adjust the pH value of the concentrate to 9.0-11.0, and then degrease it in a constant temperature water bath at 10-25℃ for 1-3 hours to obtain the degreased solution; S4. Add ethanol to the defatted solution to precipitate and obtain a precipitate. Wash and dry the precipitate to obtain low-methoxyl pectin. S5. Stir the low-methoxyl pectin, calcium source, acidulant and water evenly to obtain the passion fruit low-sugar jelly.

[0008] Optionally, the pretreatment involves drying the passion fruit to a constant weight and then pulverizing it.

[0009] Optionally, the acid hydrolysis treatment includes adding pretreated passion fruit peel to a citric acid solution with a pH of 2.0-4.0 at a material-to-liquid ratio of 1g:10-50mL, and then keeping it in a water bath at 80-95℃ for 1-2 hours.

[0010] Optionally, the pH value in S3 is 10.5; the degreasing temperature is 15°C and the time is 90 minutes.

[0011] Optionally, the low-methoxyl pectin content is 0.5-2.0% by mass, the white sugar content is 5-15% by mass, the calcium source content is 0.01-0.1% by mass, and the acidulant content is 0.1-0.3% by mass.

[0012] Optionally, passion fruit juice or pulp may be added to S5, wherein the amount of passion fruit juice or pulp added is 1%-10% of the total mass.

[0013] Optionally, the calcium source is calcium chloride or calcium lactate; the acidulant is citric acid or fruit juice.

[0014] Secondly, the present invention provides a low-sugar jelly prepared by the aforementioned preparation method.

[0015] Beneficial Effects: This invention provides a low-sugar jelly and its preparation method. The invention innovates on raw materials, turning waste into treasure: For the first time, it systematically utilizes passion fruit peel, a major agricultural waste, to prepare low-sugar jelly, achieving high-value utilization of resources, low cost, and significant environmental benefits. Furthermore, the innovative process is health-oriented: Employing an integrated "extraction-alkali modification" process, it successfully converts high-ester pectin in passion fruit peel into low-ester pectin, breaking the dependence of traditional jellies on high sugar content. The product's sugar content is significantly reduced (below 15%), aligning with healthy eating trends. The resulting jelly has excellent gel strength, a smooth texture, and the natural flavor of passion fruit, with quality comparable to commercially available products. It is easy to promote: The equipment required for this invention is simple, and the operating conditions are mild, making it very suitable for promotion and production in small and medium-sized food enterprises. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the process for preparing low-sugar jelly according to an embodiment of the present invention.

[0017] Figure 2 This is a photograph of the low-methoxyl pectin obtained in Example 1.

[0018] Figure 3 This is a photograph of the low-methoxyl pectin obtained in Comparative Example 1. Detailed Implementation

[0019] This invention provides a low-sugar jelly and its preparation method. To make the objectives, technical solutions, and effects of this invention clearer and more explicit, the invention is further described in detail below. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0020] Low-methoxyl pectin can form gels via calcium ions under low-sugar conditions, making it an ideal raw material for producing low-sugar or sugar-free gel foods. Currently, commercially available low-methoxyl pectin is mostly extracted from citrus peels and apple pomace, and is produced through acidification or amidation methods, resulting in high costs. However, there are no systematic reports or patent protection regarding the technology of using passion fruit peels, particularly through alkali modification to prepare low-methoxyl pectin and directly using it in the production of low-sugar jellies.

[0021] Based on this, this embodiment provides a method for preparing a low-sugar jelly, such as... Figure 1 As shown, it includes the following steps: S1. The pretreated passion fruit peel is acid-hydrolyzed and the filtrate is extracted. S2. Boil and concentrate the filtrate to obtain a concentrated solution; S3. Adjust the pH value of the concentrate to 9.0-11.0, and then degrease it in a constant temperature water bath at 10-25℃ for 1-3 hours to obtain the degreased solution; S4. Add ethanol to the defatted solution to precipitate and obtain a precipitate. Wash and dry the precipitate to obtain low-methoxyl pectin. S5. Stir the low-methoxyl pectin, calcium source, acidulant and water evenly to obtain the passion fruit low-sugar jelly.

[0022] It should be noted that in this embodiment, passion fruit is first pretreated, and then acid hydrolysis is performed to extract pectin. The extracted pectin is then concentrated; concentration is an essential step. Without concentration, the resulting low-methoxyl pectin is viscous but highly fluid and cannot gel. Next, the concentrated pectin undergoes alkaline deesterification modification. The pH, temperature, and time of alkaline deesterification modification are crucial to the final result. Only under suitable pH, temperature, and time can a high-yield low-methoxyl pectin with appropriate esterification degree be obtained. Finally, the obtained low-methoxyl pectin is mixed with granulated sugar, calcium chloride, passion fruit juice, and water. This allows for the production of high-quality (good gel strength) low-sugar passion fruit jelly using only a small amount of granulated sugar. For example, the jelly does not fall off when the mold is inverted, and it is very elastic and not easily broken when pressed by hand. Furthermore, the method of this invention has low repeatability error and is suitable for industrial application.

[0023] In a preferred embodiment, the pretreatment involves drying the passion fruit to a constant weight and then pulverizing it.

[0024] It should be noted that in this embodiment, drying passion fruit to a constant weight not only inhibits microbial growth and facilitates preservation, but also stabilizes pectin, prevents enzymatic hydrolysis, and reduces storage and transportation costs. Since pectin exists in plant cell walls, this invention primarily focuses on extracting it; therefore, pulverization significantly increases the contact area, thereby improving the extraction rate and yield.

[0025] In a preferred embodiment, the acid hydrolysis treatment includes adding pretreated passion fruit peel to a citric acid solution with a pH of 2.0-4.0 at a material-to-liquid ratio of 1g:10-50mL, and then incubating in a water bath at 80-95℃ for 1-2 hours. The material-to-liquid ratio can specifically be 1g:50mL, 1g:40mL, 1g:30mL, 1g:20mL, 1g:10mL, or any ratio within this range, and the pH can also be 2.0, 3.0, or 4.0.

[0026] It should be noted that passion fruit pectin is distributed on the cell walls of the peel, bound by cellulose. A relatively acidic solution (pH=2.0-4.0) is required to break down the cellulose on the cell walls, allowing the protopectin to be released into the solution (i.e., extracted). The amount of citric acid solution must also be appropriate; too little will not be enough to submerge the peel, while too much will hinder subsequent concentration.

[0027] In a preferred embodiment, the pH value in S3 is 10.5; the degreasing temperature is 15°C and the time is 90 minutes.

[0028] In some preferred embodiments, the mass percentage of low-methoxyl pectin is 0.5-2.0%, the mass percentage of white sugar is 5-15%, the mass percentage of calcium source is 0.01-0.1%, and the mass percentage of acidulant is 0.1-0.3%.

[0029] It should be noted that the low-methoxyl pectin used in this embodiment can be used to prepare a low-sugar jelly with high gel strength, excellent elasticity, and resistance to breakage, even with sugar-free or low-content white sugar.

[0030] In a preferred embodiment, passion fruit juice or pulp may also be added in step S5, wherein the amount of passion fruit juice or pulp added is 1%-10% of the total mass. Adding a certain amount of juice or pulp can enhance the flavor.

[0031] In a preferred embodiment, the calcium source is calcium chloride or calcium lactate; the acidulant is citric acid.

[0032] The present invention also provides a low-sugar jelly, prepared by the aforementioned preparation method.

[0033] The present invention will be further described below through specific embodiments.

[0034] Example 1 A method for preparing a low-sugar jelly includes the following steps: Peel pretreatment: Dry the passion fruit peel to constant weight and then crush it.

[0035] Acid hydrolysis extraction: Weigh 30g of crushed fruit peel powder and add it to a citric acid solution with pH=2.0 at a material-to-liquid ratio of 1:25 (g:mL). Then extract in a 90℃ water bath for 1.5h.

[0036] Filtration and concentration: Filter while hot using nylon cloth, collect the filtrate, and boil it on an induction cooker to concentrate it to 1 / 3 of the original volume.

[0037] Alkali deesterification: Pour the pectin concentrate into a beaker, add sodium hydroxide to adjust the pH of the solution to 10.5, and carry out the deesterification reaction in a constant temperature water bath at 15°C for 90 minutes.

[0038] Precipitation and washing: Add 1.5 times the volume of 95% ethanol to the deesterified solution and let stand for 30 minutes to allow pectin to precipitate completely. Filter, collect the precipitate, and wash it once each with 50% ethanol and 95% ethanol, then press dry.

[0039] Drying: The pectin was dried in a vacuum drying oven at 65℃ until constant weight, then pulverized to obtain a light yellow low-methoxyl pectin powder. The yield was calculated by weighing, and the degree of esterification was determined. The yield (%) was calculated as (dry weight of obtained pectin / dry weight of raw material) × 100%. The yield of the low-methoxyl pectin obtained in this example was 16.02%. The degree of esterification was determined using a pectin methoxyl esterification degree detection kit (LE-1-326, spectrophotometry) produced by Hefei Lier Biotechnology Co., Ltd. The degree of esterification of the low-methoxyl pectin obtained in this example was 43.67%.

[0040] Jelly: Weigh 1.5g of the above low-methoxyl pectin into a grinding cup, add 0.5g of white sugar to aid grinding, then add 0.03g of calcium chloride, 10g of passion fruit juice, and 40g of water. Stir well and pour into a mold. Refrigerate at 4℃ for 24 hours.

[0041] The jelly obtained in this embodiment does not fall out when the mold is inverted. When pressed by hand, the jelly is very elastic and not easily broken. Figure 2 As shown, the product has good gel strength, therefore the low-sugar jelly prepared in this embodiment is of high quality and has a low sugar content.

[0042] Comparative Example 1 Peel pretreatment: Dry the passion fruit peel to constant weight and then crush it.

[0043] Acid extraction: Weigh 30g of crushed fruit peel powder and add it to a citric acid solution with pH=2.0 at a material-to-liquid ratio of 1:25 (g:mL). Then extract in a 90℃ water bath for 1.5h and collect the filtrate.

[0044] Precipitation and washing: Add 1.5 times the volume of 95% ethanol to the collected filtrate and let stand for 30 minutes to allow the pectin to precipitate completely. Filter, collect the precipitate, wash once with 50% ethanol and once with 95% ethanol, and press dry to obtain high-methoxyl pectin.

[0045] Drying: The pectin was dried in a vacuum drying oven at 65℃ and then pulverized to obtain a light yellow high-methoxyl pectin powder.

[0046] Alkali deesterification: Place the above-mentioned yellow high-methoxyl pectin powder in a grinding cup, add a little ethanol to moisten for 10 minutes, then add 50mL of water, grind evenly to completely dissolve the pectin, and pour it into a beaker. Wash the grinding cup three times with 100mL of water, and add the washing liquid to the beaker. Adjust the pH of the pectin solution in the beaker to 10.5, and carry out the deesterification reaction in a constant temperature water bath at 15℃ for 90 minutes.

[0047] Precipitation and washing: Add 1.5 times the volume of 95% ethanol to the deesterified solution and let stand for 30 minutes to allow pectin to precipitate completely. Filter, collect the precipitate, and wash it once each with 50% ethanol and 95% ethanol, then press dry.

[0048] Drying and Finished Product: The pectin was dried in a vacuum drying oven at 65℃ until constant weight, then pulverized to obtain a light yellow low-methoxyl pectin powder. The yield was calculated by weighing, and the degree of esterification was determined. The yield of the low-methoxyl pectin obtained in this comparative example was 4.56%. The degree of esterification was determined using the pectin methoxyl esterification degree test kit (LE-1-326, spectrophotometry) produced by Hefei Lier Biotechnology Co., Ltd. The degree of esterification of the low-methoxyl pectin in this comparative example was 31.66%.

[0049] Jelly: Weigh 1.5g of the above low-methoxyl pectin into a grinding cup, add 0.5g of white sugar to aid grinding, then add 0.03g of calcium chloride, 10g of passion fruit juice, and 40g of water. Stir well and pour into a mold. You will see the jelly quickly gel. Refrigerate at 4°C for 24 hours.

[0050] The jelly prepared in this comparative example, although able to form a gel, exhibited water separation. When the mold was inverted, the jelly barely detached, but crumbled easily when pressed by hand, demonstrating very poor gel strength, making it unsuitable for producing low-sugar jelly. Figure 3 As shown.

[0051] In summary, this invention provides a low-sugar jelly and its preparation method, featuring innovative raw materials that turn waste into treasure: For the first time, it systematically utilizes passion fruit peel, a major agricultural waste, to prepare low-sugar jelly, achieving high-value resource utilization at low cost and with significant environmental benefits. Furthermore, the innovative process is health-oriented: employing an integrated "extraction-alkali modification" process, it successfully converts the high-ester pectin in passion fruit peel into low-ester pectin, breaking the dependence of traditional jellies on high sugar content. The product's sugar content is significantly reduced (below 15%), aligning with healthy eating trends. The product is of excellent quality: the resulting jelly has moderate gel strength, a smooth texture, and the natural flavor of passion fruit, comparable in quality to commercially available products. It is easy to promote: the equipment required for this invention is simple, and the operating conditions are mild, making it highly suitable for promotion and production in small and medium-sized food enterprises.

[0052] It should be understood that the application of the present invention is not limited to the examples above. Those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.

Claims

1. A method for preparing a low-sugar jelly, characterized in that, Includes the following steps: S1. The pretreated passion fruit peel is acid-hydrolyzed and the filtrate is extracted. S2. Boil and concentrate the filtrate to obtain a concentrated solution; S3. Adjust the pH value of the concentrate to 9.0-11.0, and then degrease it in a constant temperature water bath at 10-25℃ for 1-3 hours to obtain the degreased solution; S4. Add ethanol to the defatted solution to precipitate the product, and wash and dry the precipitate to obtain low-methoxyl pectin. S5. Stir the low-methoxyl pectin, calcium source, acidulant and water evenly to obtain the low-sugar jelly.

2. The method for preparing a low-sugar jelly according to claim 1, characterized in that, The pretreatment involves drying the passion fruit to a constant weight and then pulverizing it.

3. The method for preparing a low-sugar jelly according to claim 1, characterized in that, The acid hydrolysis treatment involves adding pretreated passion fruit peel to a citric acid solution with a pH of 2.0-4.0 at a material-to-liquid ratio of 1g:10-50mL, and then keeping it in a water bath at 80-95℃ for 1-2 hours.

4. The method for preparing a low-sugar jelly according to claim 1, characterized in that, The pH value in S3 is 10.5; the degreasing temperature is 15℃ and the time is 90 minutes.

5. The method for preparing a low-sugar jelly according to claim 1, characterized in that, In S5, the mass percentage of low-methoxyl pectin is 0.5-2.0%, the mass percentage of white sugar is 5-15%, the mass percentage of calcium source is 0.01-0.1%, and the mass percentage of acidulant is 0.1-0.3%.

6. The method for preparing a low-sugar jelly according to claim 1, characterized in that, Passion fruit juice or pulp can also be added to S5, and the amount of passion fruit juice or pulp added is 1%-10% of the total mass.

7. The method for preparing a low-sugar jelly according to claim 1, characterized in that, The calcium source is calcium chloride or calcium lactate; the acidulant is citric acid or fruit juice.

8. A low-sugar jelly, characterized in that, Prepared by the preparation method according to any one of claims 1-7.

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