Embedded rose yoghourt and preparation method thereof

Abstract

The invention belongs to the technical field of dairy product processing and food biology, and discloses embedded rose yoghourt and a preparation method thereof. The method comprises the following steps: performing ultrasonic-assisted extraction on fresh edible rose petals under an acidic condition, filtering, adding a color fixative, and performing vacuum concentration to obtain a rose concentrated stock solution; mixing the rose concentrated stock solution with a compound polysaccharide wall material solution composed of sodium alginate and low-ester pectin, and dropwise adding the mixture into a cross-linking curing bath to prepare rose color-protecting pellets; standardizing fresh milk, adding sugar, sterilizing, inoculating and fermenting to obtain a yoghourt base; and cold-doping the rose color-protecting pellets into a yoghurt substrate under a sterile condition, and filling, refrigerating and after-ripening to obtain the embedded rose yoghurt. By means of the process of compound polysaccharide embedding and cold doping after fermentation, the stability of rose anthocyanin and flavor components is improved, migration of pigments to a yoghourt base is reduced, the milky white appearance of the yoghourt base can be kept, and the product is endowed with good rose flavor and particle chewing feeling.

Description

Technical Field

[0001] This invention belongs to the field of dairy processing and food biotechnology, specifically relating to an encapsulated rose yogurt and its preparation method. Background Technology

[0002] Yogurt is a fermented dairy product made primarily from milk through lactic acid bacteria fermentation. It has long been popular due to its high nutritional value, good flavor, and ease of digestion and absorption. With the development of functional and novel flavored dairy products, the application of natural floral ingredients in yogurt is gradually increasing. Edible roses, especially Yunnan edible rose varieties, are rich in anthocyanins, polyphenols, and volatile aromatic components, possessing high nutritional and sensory development value. Applying roses to yogurt products helps enhance the product's overall color, aroma characteristics, and functional attributes.

[0003] In existing technologies, floral-flavored fermented milk often involves directly adding floral nectar, flower extracts, or flavorings to the fermented milk system, or performing post-fermentation ripening, homogenization, and further drying after fermentation. However, existing technologies still struggle to address issues such as the migration and staining of rose pigments in the yogurt system, the easy degradation of anthocyanins during fermentation and storage, the loss of aroma during processing, and the lack of a chewy texture in the product. Especially for products that require maintaining the milky white appearance of the yogurt base while achieving the visual effect of purple-red rose particles and a popping boba-like texture, existing technologies lack effective solutions.

[0004] Therefore, there is an urgent need for a new method for preparing flower-flavored fermented milk to solve the above problems, provide solid and reliable technical support for the research and development of specialty functional dairy products, the industrialization of deep processing of flower agricultural products, and the flavor innovation and upgrading of the dairy industry, and also lay a technical foundation for expanding the deep processing and utilization of flowers and enriching the categories of fermented milk products. Summary of the Invention

[0005] To address or partially address the problems existing in related technologies, this application provides an encapsulated rose yogurt and its preparation method, thereby solving the problems of poor color stability, low anthocyanin retention rate, easy loss of aroma, and insufficient product taste layers in existing rose yogurt.

[0006] This application provides a method for preparing encapsulated rose yogurt, comprising the following steps: S1. Rose petals and water were mixed in a ratio of 1:(8-12) (g / mL), and extracted with ultrasound under acidic conditions. After filtration, a color-protecting agent was added, and the mixture was concentrated under reduced pressure to obtain concentrated rose extract. The solid content of the rose concentrate is 10%-20% by mass fraction; The acidic conditions refer to the pH of the extract being 3.0-3.5 and the temperature being 30-40℃. S2, mix the concentrated rose extract obtained in step S1 with the polysaccharide wall material solution to obtain a core material solution; add the core material solution dropwise to a crosslinking curing bath for curing and crosslinking, and wash after curing to obtain rose color-protecting microspheres for later use; The polysaccharide wall material solution is prepared by mixing sodium alginate and low-ester pectin and then adding it to water at a constant temperature. The crosslinking curing bath is a 1.5%-2.0% calcium chloride solution containing 0.1% citric acid, and the curing and crosslinking time is 30-45 min; S3: After standardizing fresh milk, add white sugar, sterilize and cool, inoculate with starter culture for fermentation, break the milk and cool down after fermentation to obtain yogurt base for later use; The starter culture includes Lactobacillus bulgaricus and Streptococcus thermophilus, the fermentation inoculation temperature is 40-43℃, and the final pH value of the fermentation is 4.5-4.6; S4. The rose color-protecting microspheres obtained in step S2 are incorporated into the yogurt base obtained in step S3 under aseptic conditions. After stirring evenly, the mixture is filled, refrigerated, and then matured to obtain embedded rose yogurt.

[0007] Furthermore, in step S2, the mass ratio of sodium alginate to low-ester pectin is 3:1-4:1.

[0008] Furthermore, in step S2, the volume ratio of the concentrated rose extract to the polysaccharide wall material solution is 1:3-1:5.

[0009] Furthermore, in step S3, the amount of white sugar added is 5%-8% of the mass of fresh milk.

[0010] Furthermore, the sterilization temperature in step S3 is 90-95℃, and the sterilization time is 5-10 minutes.

[0011] Furthermore, in step S4, the temperature at which the rose color-protecting microspheres are incorporated into the yogurt base is 15-20°C.

[0012] Furthermore, in step S4, the amount of rose color-protecting microspheres added is 5%-10% of the total mass of yogurt.

[0013] Furthermore, the ultrasound-assisted extraction time in step S1 is 20-40 minutes.

[0014] Furthermore, the color-protecting agent in step S1 is phytic acid, and the amount added is 0.03%-0.08% of the extract mass.

[0015] This application also provides an encapsulated rose yogurt, which is prepared by the above-described preparation method.

[0016] Beneficial effects 1. This invention uses sodium alginate and low-ester pectin to form an embedding wall material, and then cross-links and cures it to obtain rose color-protecting microspheres, which can protect the anthocyanins and flavor components in roses. The anthocyanin retention rate is 85.3%, which significantly improves its stability in yogurt systems.

[0017] 2. This invention employs a "pre-encapsulation followed by cold blending" process to confine rose pigments within the microspheres, reducing their migration into the yogurt base. This helps maintain the milky white appearance of the yogurt base and improves the product's visual quality. It also prevents the active rose components from directly experiencing the acidification environment and prolonged effects of yogurt fermentation, thereby reducing anthocyanin degradation and aroma loss.

[0018] 3. The rose-colored microspheres obtained by this invention can give yogurt a unique granular texture and chewiness, release rose flavor when consumed, and enhance the sensory level and market competitiveness of the product.

[0019] 4. This invention targets refrigerated ready-to-eat yogurt products, employing a complex polysaccharide encapsulation, color isolation, and aseptic cold blending process after fermentation, and limiting the mass ratio of the wall material, so that the yogurt has good structural stability in a low pH environment, with an encapsulation rate of 89.4%.

[0020] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and do not limit this application. Attached Figure Description

[0021] The above and other objects, features and advantages of this application will become more apparent from the more detailed description of exemplary embodiments thereof in conjunction with the accompanying drawings.

[0022] Figure 1 This is a flowchart illustrating the preparation process of the embedded rose yogurt of the present invention.

[0023] Figure 2 The figure shows the evaluation results of microsphere encapsulation rate and sphericity under different wall material ratios.

[0024] Figure 3 This is a graph showing the change in overall color difference ΔE during storage of the yogurt of this invention.

[0025] Figure 4 The sensory evaluation results of fermented milk with different addition methods are shown in the figure. Detailed Implementation

[0026] Embodiments of this application will now be described in more detail with reference to the accompanying drawings. While embodiments of this application are shown in the drawings, it should be understood that this application may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to make this application more thorough and complete, and to fully convey the scope of this application to those skilled in the art.

[0027] Unless otherwise specified, all reagents and materials used in the following examples were purchased from the market.

[0028] Example 1 like Figure 1 As shown, the solution of this application includes the following steps: S1. Preparation of Rose Concentrate Weigh 100g of fresh "Dark Red" rose petals and add water at a material-to-liquid ratio of 1:10 (g / mL). Adjust the pH of the extract to 3.2 using citric acid and perform ultrasonic-assisted extraction at 35℃ for 30 minutes. After filtration, add 0.05% phytic acid (by weight of the extract) as a color-protecting agent, and then concentrate under reduced pressure to obtain a concentrated rose extract with a solid content of 15%.

[0029] S2, Preparation of Rose Color-Protecting Microspheres Weigh 1.5g of sodium alginate and 0.5g of low-ester pectin and dissolve them in 100mL of constant temperature water. Stir until completely dissolved, then mix with the concentrated rose extract obtained in step S1 at a volume ratio of 4:1 to obtain a core material solution. Using a granulation device, add the core material solution dropwise to a 2.0% calcium chloride solution containing 0.1% citric acid. After curing for 30 minutes, remove and wash with water to obtain rose color-protecting microspheres.

[0030] S3, Yogurt base fermentation Fresh milk was standardized and then white sugar was added at a rate of 6% (w / w) of the milk mass. The milk was sterilized at 95°C for 5 minutes and cooled to 42°C. Lactobacillus bulgaricus and Streptococcus thermophilus (source: China Industrial Microbial Culture Collection Center (CICC); catalog number: Lactobacillus bulgaricus CICC 6103, Streptococcus thermophilus CICC 6038) were then inoculated for fermentation. Fermentation was terminated when the pH value dropped to 4.5. The milk was then broken down and cooled to 15°C to obtain the yogurt base.

[0031] S4. Aseptic cold mixing and filling Under aseptic conditions, the rose color-protecting microspheres obtained in step S2 were added to the yogurt base at a ratio of 8% of the total mass of the yogurt. After being stirred evenly by static mixing, the mixture was filled and refrigerated at 4°C for post-maturation to obtain embedded rose yogurt.

[0032] Example 2 This example investigated the effect of different ratios of sodium alginate to low-ester pectin on the encapsulation effect of microspheres. In addition to the 3:1 ratio group in Example 1, three other ratio groups were set up: 1:0, 2:1, and 4:1. In the 4:1 group, the amounts of sodium alginate and low-ester pectin were 2.0 g and 0.5 g, respectively, and the calcium chloride concentration in the crosslinking curing bath was 1.5%. For the other groups, only the amounts of the two wall materials were adjusted according to their respective mass ratios; all other conditions were the same as in Example 1. The encapsulation rate and sphericity results for each ratio group are shown below. Figure 2 Among them, the 3:1 group had the highest anthocyanin encapsulation rate, at 89.4%.

[0033] Example 3 This embodiment is basically the same as Embodiment 1, except that in step S4, the amount of rose color-protecting microspheres added is 5% of the total mass of the yogurt. This embodiment is set up to compare the effects of different addition amounts on the overall color, texture, and sensory acceptance. The other conditions are the same as in Embodiment 1. The results show that when the amount of rose color-protecting microspheres added is 5%, the yogurt product still maintains good texture and color stability, but the overall color contrast and rose flavor intensity are relatively low. When the addition amount is 8%, the microspheres are more evenly distributed in the product, the overall color contrast is more obvious, and the sensory acceptance is higher. Therefore, appropriately increasing the amount of rose color-protecting microspheres added is beneficial to improving the overall color and flavor quality of the product, indicating that the addition range (5%-10%) defined by this invention can achieve synergistic optimization of overall color and flavor while ensuring product structural stability.

[0034] Comparative Example 1 This comparative example is essentially the same as Example 1, except that the rose concentrate obtained in step S1 is not encapsulated in step S2, but is directly cold-mixed into the yogurt base in step S4 at an amount equivalent to that in Example 1. This comparative example is set up to illustrate the effect of the encapsulation step on color stability and anthocyanin retention rate; all other conditions are the same as in Example 1. The following tests were performed: 1. Color stability determination The products obtained in Example 1 and Comparative Example 1 were stored at 4°C for 21 days, and the color change of the samples was measured using a colorimeter. The results are shown in Table 1.

[0035] Table 1. Color difference comparison of yogurt samples after 21 days of storage The data are the mean ± standard deviation of three parallel experiments. The results show that, compared to the comparative example, the overall color difference of the sample in the embodiment was significantly reduced. This invention, through encapsulation technology, can effectively inhibit the migration of rose pigment to the yogurt substrate, significantly improving the product's appearance stability.

[0036] 2. Anthocyanin retention rate determination The total anthocyanin content in the samples after 21 days of storage was determined using the pH differential method. The results showed that the anthocyanin retention rate in the microcapsules of Example 1 was 85.3%, while the retention rate in Comparative Example 1 was only 42.1%. This indicates that the encapsulation process of the present invention can significantly improve the storage stability of anthocyanins in yogurt systems.

[0037] 3. Sensory evaluation Twenty experienced evaluators were invited to conduct sensory evaluations of the samples. The evaluation results are shown in Table 2 and... Figure 2 .

[0038] Table 2 Sensory evaluation results of rose yogurt The results showed that the product treated with embedding was significantly better than the control sample with directly added rose concentrate in terms of appearance, texture, and taste.

[0039] The various embodiments of this application have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical application, or improvement of the technology in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A method for preparing an encapsulated rose yogurt, characterized in that, Includes the following steps: S1. Rose petals and water were mixed in a ratio of 1:(8-12) (g / mL), and extracted with ultrasound under acidic conditions. After filtration, a color-protecting agent was added, and the mixture was concentrated under reduced pressure to obtain concentrated rose extract. The solid content of the rose concentrate is 10%-20% by mass fraction; The acidic conditions refer to the pH of the extract being 3.0-3.5 and the temperature being 30-40℃. S2, mix the concentrated rose extract obtained in step S1 with the polysaccharide wall material solution to obtain a core material solution; add the core material solution dropwise to a crosslinking curing bath for curing and crosslinking, and wash after curing to obtain rose color-protecting microspheres for later use; The polysaccharide wall material solution is prepared by mixing sodium alginate and low-ester pectin and then adding it to water at a constant temperature. The crosslinking curing bath is a 1.5%-2.0% calcium chloride solution containing 0.1% citric acid, and the curing and crosslinking time is 30-45 min; S3: After standardizing fresh milk, add white sugar, sterilize and cool, inoculate with starter culture for fermentation, break the milk and cool down after fermentation to obtain yogurt base for later use; The starter culture includes Lactobacillus bulgaricus and Streptococcus thermophilus, the fermentation inoculation temperature is 40-43℃, and the final fermentation pH is 4.5-4.6; S4. The rose color-protecting microspheres obtained in step S2 are incorporated into the yogurt base obtained in step S3 under aseptic conditions. After stirring evenly, the mixture is filled, refrigerated, and then matured to obtain embedded rose yogurt.

2. The preparation method according to claim 1, characterized in that, In step S2, the mass ratio of sodium alginate to low-ester pectin is 3:1-4:

1.

3. The preparation method according to claim 1, characterized in that, In step S2, the volume ratio of concentrated rose extract to polysaccharide wall material solution is 1:3-1:

5.

4. The preparation method according to claim 1, characterized in that, In step S3, the amount of white sugar added is 5%-8% of the mass of fresh milk.

5. The preparation method according to claim 1, characterized in that, The sterilization temperature in step S3 is 90-95℃, and the sterilization time is 5-10 minutes.

6. The preparation method according to claim 1, characterized in that, The temperature at which the rose color-protecting microspheres are incorporated into the yogurt base in step S4 is 15-20℃.

7. The preparation method according to claim 1, characterized in that, In step S4, the amount of rose color-protecting microspheres added is 5%-10% of the total mass of yogurt.

8. The preparation method according to claim 1, characterized in that, The ultrasound-assisted extraction time in step S1 is 20-40 minutes.

9. The preparation method according to claim 1, characterized in that, The color-protecting agent in step S1 is phytic acid, and the amount added is 0.03%-0.08% of the mass of the extract.

10. An encapsulated rose yogurt, characterized in that, The encapsulated rose yogurt is prepared by the preparation method described in any one of claims 1-9.

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