Preparation method of low-sugar high-gelation strawberry jam

Abstract

The invention belongs to the technical field of jam product processing, and provides a preparation method of low-sugar high-gelation strawberry jam. The preparation method is simple in process and easy to operate, the specific filler is introduced into the prepared strawberry jam, the water binding capacity is greatly improved from 3.15 g / g to 10.81 g / g, the problem that traditional jam is prone to water bleeding is effectively solved, the jam is more uniform and fine in texture and better in taste, the hardness, cohesiveness and adhesiveness of the jam are greatly improved, and the strawberry jam is suitable for large-scale production. In addition, the viscoelasticity and the stability of the jam are also remarkably improved, and the shelf life of the jam is prolonged.

Description

Technical Field

[0001] The present invention belongs to the technical field of jam product processing, and particularly relates to a method for preparing low-sugar and highly gelled strawberry jam. Background Art

[0002] With the continuous improvement of consumers' requirements for the nutritional and health qualities of traditional foods, high-sugar jams have gradually become difficult to meet their health needs. Therefore, the development of low-sugar jam products shows broad prospects. However, reducing the amount of sucrose used or even completely eliminating it will affect the flavor of the jam and also have an adverse impact on the viscosity, structure, osmotic pressure and other properties of the jam, making it less acceptable to consumers. For this reason, the research focus should be on how to maintain the sensory properties, texture, rheological properties and storage stability of low-sugar jams so that their taste is close to that of traditional high-sugar jams and meets consumers' demand for a similar taste. Summary of the Invention

[0003] To solve the above technical problems, the present invention provides a method for preparing low-sugar and highly gelled strawberry jam. This method is simple to operate and easy to implement. By introducing a specific filler, the prepared strawberry jam has achieved a significant improvement in water retention, effectively solving problems such as easy water separation in traditional jams, making the texture of the jam more uniform and delicate, the taste more superior, and the shelf life longer.

[0004] The technical solution of the present invention is: a method for preparing low-sugar and highly gelled strawberry jam, mainly including the following steps: (1) Strawberry selection: Select commercially available strawberries with a maturity of 70%-80% and a soluble solid content between 8-12°Brix, and remove fruits damaged by pests, diseases or mechanical injuries; (2) Stem removal and cleaning: Remove the fruit stalks, rinse with running water for 90 s, soak in 0.1% NaClO solution for 5 min to kill surface microorganisms, and then rinse with deionized water 2-3 times to obtain strawberry pulp; (3) Dicing and color protection: Cut the strawberry pulp obtained in (2) into cubes with a side length of 3-5 mm, soak in 1‰ w / w ascorbic acid solution for 15-30 min, take out and drain to obtain strawberry raw materials; (4) Blending: Add 0.02-0.05% w / w sweetener to the strawberry raw materials obtained in (3), stir at 50 rpm for 120 s for pre-mixing, and then add 1-3% w / w filler, shear evenly at 1200 rpm for 60 s for full mixing; (5) Boiling: Place the mixed material after shearing in (4) at 60°C and heat for 10 min, then boil at 100°C for 20-40 min to obtain a homogeneous strawberry jam system.

[0005] Preferably, in (1), the soluble solids content of the strawberries is 10 °Brix.

[0006] Preferably, in (3), the soaking time is 20 min.

[0007] Preferably, in (4), the filler is selected from any one of low-methoxyl pectin, sodium alginate, agar, and citrus fiber; the sweetener is sucralose.

[0008] The present invention has the following advantages and effects compared with the prior art: (1) By introducing a filler, the water-holding capacity of the jam is greatly increased from 3.15 g / g to 10.81 g / g, effectively solving the problem of easy water separation of traditional jams, making the texture of the jam more uniform and delicate, and the taste better; (2) The use of the filler significantly improves the hardness of the jam. The hardness of the jam filled with low-methoxyl pectin is as high as 33.28 ± 0.68 g, much higher than 22.87 ± 0.18 g of the jam without filler; at the same time, the jam filled with citrus fiber also shows excellent performance in cohesiveness and adhesiveness, with a cohesiveness of 0.81 ± 0.02 and an adhesiveness of 23.01 ± 0.85 g, making the taste of the jam more full and the chewing feeling stronger; (3) The addition of citrus fiber constructs a strong elastic and viscous network structure for the jam, significantly improving the viscoelasticity and stability of the jam. This improvement not only enhances the taste level of the jam but also extends the shelf life of the product and improves the consumer's eating experience; (4) By adding a suitable filler, especially sodium alginate and citrus fiber, the present invention successfully reduces the water separation rate of the low-sugar jam, effectively avoiding water loss during storage of the jam, and further improving the quality and stability of the jam. Description of the Drawings

[0009] Figure 1 are the storage modulus G' and loss modulus G'' of the strawberry jam. Detailed Embodiments

[0010] In order to enable those skilled in the art to better understand the present invention, the present invention will be further described below in conjunction with specific embodiments.

[0011] Example 1 A method for preparing a low-sugar and high-gelatinized strawberry jam mainly includes the following steps: (1) Strawberry selection: Select commercially available strawberries with a maturity of seven or eight and a soluble solids content of 10 °Brix, and remove fruits with diseases, pests, and mechanical damage; (2) Stem removal and cleaning: Remove the fruit stalk, rinse with running water for 90 seconds, soak in 0.1% NaClO solution for 5 minutes to kill surface microorganisms, and then rinse with deionized water three times to obtain the strawberry pulp; (3) Dicing and color protection: Cut the strawberry pulp obtained in (2) into cubes with a side length of 4 mm, soak them in a 1‰ w / w ascorbic acid solution for 20 min, take them out and drain them to obtain a strawberry raw material; (4) Preparation: Add 0.03% w / w sucralose to the strawberry raw material obtained in (3), stir at 50 rpm for 120 s for premixing, then add 2% w / w citrus fiber, shear at 1200 rpm for 60 s, and mix thoroughly; (5) Boiling: The sheared mixture in (4) is heated at 60°C for 10 min, and then boiled at 100°C for 30 min to obtain a uniform strawberry jam.

[0012] Example 2 A method for preparing low-sugar and high-gelatinized strawberry jam mainly comprises the following steps: (1) Strawberry selection: Select commercially available strawberries with a maturity of 70% to 80% and a soluble solids content of 8°Brix, and remove those with pests and diseases or mechanical damage; (2) Stem removal and cleaning: Remove the fruit stalk, rinse with running water for 90 seconds, soak in 0.1% NaClO solution for 5 minutes to kill surface microorganisms, and then rinse twice with deionized water to obtain the strawberry pulp; (3) Dicing and color protection: Cut the strawberry pulp obtained in (2) into cubes with a side length of 3 mm, soak them in a 1‰ w / w ascorbic acid solution for 15 min, take them out and drain them to obtain a strawberry raw material; (4) Preparation: Add 0.02% w / w sucralose to the strawberry raw material obtained in (3), stir at 50 rpm for 120 s for premixing, then add 1% w / w sodium alginate, shear at 1200 rpm for 60 s, and mix thoroughly; (5) Boiling: The sheared mixture in (4) is heated at 60°C for 10 min, and then boiled at 100°C for 20 min to obtain a uniform strawberry jam.

[0013] Example 3 A method for preparing low-sugar and high-gelatinized strawberry jam mainly comprises the following steps: (1) Strawberry sorting: Select commercially available strawberries with a maturity of 70% to 80% and a soluble solids content of 12° Brix, and remove those with pests and diseases or mechanical damage; (2) Stem removal and cleaning: Remove the fruit stalks, rinse with running water for 90 s, soak in 0.1% NaClO solution for 5 min to kill surface microorganisms, and then rinse 3 times with deionized water to obtain strawberry pulp; (3) Dicing and color protection: Cut the strawberry pulp obtained in (2) into cubes with a side length of 5 mm, soak in 1‰ w / w ascorbic acid solution for 30 min, take out and drain to obtain strawberry raw materials; (4) Blending: Add 0.05% w / w sucralose to the strawberry raw materials obtained in (3), stir at 50 rpm for 120 s for pre-mixing, and then add 3% w / w agar, shear uniformly at 1200 rpm for 60 s for full mixing; (5) Boiling: Place the mixed material after shearing in (4) at 60 °C and heat for 10 min, then boil at 100 °C for 40 min to obtain a homogeneous strawberry jam.

[0014] Example 4 A method for preparing low-sugar and high-gelation strawberry jam mainly includes the following steps: (1) Strawberry selection: Select commercially available strawberries with a maturity of seven or eight and a soluble solid content of 10 °Brix, and remove fruits with diseases, pests and mechanical damage; (2) Stem removal and cleaning: Remove the fruit stalks, rinse with running water for 90 s, soak in 0.1% NaClO solution for 5 min to kill surface microorganisms, and then rinse 3 times with deionized water to obtain strawberry pulp; (3) Dicing and color protection: Cut the strawberry pulp obtained in (2) into cubes with a side length of 4 mm, soak in 1‰ w / w ascorbic acid solution for 20 min, take out and drain to obtain strawberry raw materials; (4) Blending: Add 0.03% w / w sucralose to the strawberry raw materials obtained in (3), stir at 50 rpm for 120 s for pre-mixing, and then add 2% w / w low-methoxyl pectin, shear uniformly at 1200 rpm for 60 s for full mixing; (5) Boiling: Place the mixed material after shearing in (4) at 60 °C and heat for 10 min, then boil at 100 °C for 30 min to obtain a homogeneous strawberry jam.

[0015] Performance detection of Example 5 Detect the performance of the strawberry jam prepared by the present invention. The performance indexes to be detected include water holding capacity, texture, elasticity and viscosity, water separation rate and other indexes.

[0016] 1. Water holding capacity In the low-sugar jam system, after adding 2% filler and stirring and boiling evenly, let it stand still at low temperature for 8 h, weigh and add it to a centrifuge tube, then centrifuge at 5000 rpm / 10 min, discard the supernatant, and weigh.

[0017] WHC = (W3 - W2 - W1) / W1 Among them, WHC—water holding capacity, g / g; W1—mass of the filler sample, g; W2—mass of the centrifuge tube, g; W3—total mass of the centrifuge tube and the residue, g.

[0018] Table 1 Detection results of the water holding capacity of strawberry jam / Water holding capacity (g / g) Without filling 3.15±0.02b Corn starch 2.21±0.08a Gelatin 3.29±0.13b Low methoxyl pectin 5.22±0.81c Sodium alginate 7.91±1.02d Agar 8.22±0.99d Citrus fiber 10.81±0.43e

[0019] Note: The marked letters a, b, c, d, e indicate significant differences between groups. The same letter indicates no significant difference, and different letters indicate significant differences ( P <0.05).

[0020] The water holding capacity was measured after adding 2% of different fillers to the low-sugar jam system and subjecting it to specific treatments. The detection results are shown in Table 1. The data in the table show that there are significant differences in the water holding capacity of different fillers. Among them, citrus fiber has the best water holding capacity, reaching 10.81 g / g, which can effectively bind the water in the jam; agar and sodium alginate have relatively strong water holding capacity, 8.22 g / g and 7.91 g / g respectively, which can retain water well; low-methoxyl pectin has a general water holding capacity of 5.22 g / g; and the water holding capacity is the worst without filler, only 3.15 g / g. Not all fillers can have a significant effect on the water holding capacity of low-sugar jam. Therefore, finding a suitable filler is crucial for significantly improving the water holding capacity of low-sugar jam.

[0021] 2. Texture Texture properties are an important part that cannot be ignored when evaluating the quality of semi-solid foods such as jam. The TPA mode of the texture analyzer is the most commonly used test mode for analyzing the texture of foods. The texture characteristic curve obtained through TPA testing can well describe the characteristics of semi-solid foods such as hardness, cohesiveness, and adhesiveness.

[0022] Place the strawberry jam in a cup and let it stand still for about 20 min until its temperature reaches room temperature and is in a stable state. Then, use the TPA mode for measurement. Set the pre-test speed to 1 mm / s, the test speed to 1 mm / s, the post-test speed to 2 mm / s, and the pressing distance to 10 mm.

[0023] Table 2 Detection results of the texture properties of strawberry jam Hardness / g Cohesiveness Gumminess / g Without filling 22.87±0.18a 0.45±0.03a 14.82±0.22a Low methoxyl pectin 33.28±0.68c 0.49±0.02a 20.19±0.67b Sodium alginate 30.89±0.55b 0.66±0.08b 22.10±0.09c Agar 31.68±0.28b 0.55±0.03a 21.71±0.26c Citrus fiber 30.72±1.11b 0.81±0.02c 23.01±0.85d

[0024] As shown in the data in Table 2 above, in terms of hardness, the hardness of the unfilled jam was 22.87 ± 0.18 g, which was significantly lower than that of the jams with fillers added. Among them, the hardness of the jam filled with low-methoxyl pectin was the highest, reaching 33.28 ± 0.68 g. The hardness values of the jams filled with sodium alginate, agar, and citrus fiber were relatively close, indicating that the filler could effectively improve the hardness of the jam.

[0025] In terms of cohesiveness, the cohesiveness of the jam filled with citrus fiber was the best, being 0.81 ± 0.02. Sodium alginate was the second, while the cohesiveness of the unfilled, low-methoxyl pectin-filled, and agar-filled jams was relatively low, indicating that citrus fiber and sodium alginate could make the internal structure of the jam more stable.

[0026] In terms of adhesiveness, the value of the jam filled with citrus fiber was also the highest, being 23.01 ± 0.85 g, indicating that it had a better chewing feeling. The adhesiveness of the jams filled with sodium alginate, agar, and low-methoxyl pectin followed in order, and the adhesiveness of the unfilled jam was the lowest.

[0027] Overall, from the test results in Table 2, different fillers had significant effects on the hardness, cohesiveness, and adhesiveness of the low-sugar jam. Among them, citrus fiber had a relatively prominent comprehensive performance in improving the texture.

[0028] 3. Rheological properties Set the test temperature of the rheometer to 23 °C, the frequency to be set from 1 Hz to 10 Hz, and the strain magnitude to be selected within the linear viscoelastic region. Measure the elastic modulus G’ and viscous modulus G” during the process of frequency change.

[0029] The viscoelasticity of the low-sugar jam is represented by the storage modulus G’ and loss modulus G” respectively. G’ represents the ability of the sample to store energy, that is, the elastic characteristic, which describes the degree of deformation when an external force acts on the sample. The higher G’ is, the greater the gel strength of the sample and the stronger the elastic performance. If G’ is 0, the sample shows pure viscosity. G” represents the ability of the sample to release energy, that is, the viscous characteristic, which describes the property of hindering the sample from flowing when an external force acts on it. The higher G” is, the stronger the viscous performance of the sample. If G” is 0, the sample shows pure elasticity.

[0030] As Figure 1 shown, the G’ and G” values of the citrus fiber group were significantly higher than those of other fillers at each angular frequency. This indicates that citrus fiber can construct a stronger elastic and viscous network structure for the jam, making the jam have better viscoelasticity and stability. From a microscopic perspective, it may be the special structure and intermolecular interaction of citrus fiber that enable it to form a denser and more stable network in the jam system, effectively resisting the external shear force.

[0031] 4. The water separation rate after one month of storage After storing strawberry jam at 23°C for 1 month, centrifuge it at 1000 rpm for 5 minutes. The ratio of the weight of the separated water to the total mass is the water separation rate.

[0032] Table 3 Water separation rate test of strawberry jam after 1-month storage Syneresis rate (%) Without filling 9.5±1.8c Low methoxyl pectin 8.2±0.9c Sodium alginate 3.9±0.8a Agar 5.2±0.5b Citrus fiber 3.1±0.3a

[0033] The results in Table 3 show that the water separation rate of the low-sugar jam without filling is the highest, at 9.5%. The water separation rate of the low-methoxyl pectin-filled jam is 8.2%, and both values are relatively high. In contrast, the water separation rate of the agar-filled jam drops to 5.2%, while the water separation rates of the sodium alginate- and citrus fiber-filled jams are even lower, at 3.9% and 3.1% respectively. This indicates that adding a suitable filler can significantly reduce the water separation rate of low-sugar jam, and sodium alginate and citrus fiber are particularly outstanding in inhibiting water separation.

[0034] In summary, the preparation method of the low-sugar and high-gelation strawberry jam provided by the present invention has a simple process and is easy to operate. The prepared jam, by adding specific fillers, not only significantly improves the water retention, texture properties, and rheological characteristics of the jam, but also reduces the water separation rate, thereby improving the overall quality and stability of the jam, making it excellent in terms of taste, texture, and shelf life, and having high market value and application prospects.

[0035] The above are only the preferred embodiments of the present invention, and do not limit the patent scope of the present invention. All equivalent changes and modifications made according to the scope of the present invention should still fall within the scope covered by the present invention.

Claims

1. A method for preparing low-sugar and high-gelatinized strawberry jam, characterized in that: The main steps include: (1) Strawberry sorting: Select commercially available strawberries with a maturity of 70% to 80% and a soluble solids content between 8 and 12° Brix, and remove those with pests and diseases or mechanical damage; (2) Stem removal and cleaning: Remove the fruit stalk, rinse with running water for 90 seconds, soak in 0.1% NaClO solution for 5 minutes to kill surface microorganisms, and then rinse with deionized water 2-3 times to obtain the strawberry pulp; (3) Dicing and color protection: Cut the strawberry pulp obtained in (2) into cubes with a side length of 3-5 mm, soak them in a 1‰ w / w ascorbic acid solution for 15-30 min, take them out and drain them to obtain a strawberry raw material; (4) Preparation: Add 0.02-0.05% w / w sweetener to the strawberry raw material obtained in (3), stir at 50 rpm for 120 s to pre-mix, then add 1-3% w / w filler, shear at 1200 rpm for 60 s to mix thoroughly; (5) Boiling: The sheared mixture in (4) is heated at 60°C for 10 min, and then boiled at 100°C for 20-40 min to obtain a uniform strawberry jam.

2. The preparation method as claimed in claim 1, characterized in that (1), wherein the soluble solids content of the strawberry is 10°Brix.

3. The preparation method as claimed in claim 1, characterized in that (3), the soaking time is 20 minutes.

4. The preparation method as claimed in claim 1, characterized in that (4), wherein the filler is selected from any one of low methoxyl pectin, sodium alginate, agar, and citrus fiber; The sweetener is sucralose.

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