Cold-extracted yoghurt for treating dysphagia and preparation method thereof

Abstract

The invention belongs to the technical field of yoghurt, and particularly relates to cold-extracted dry dysphagia yoghurt and a preparation method thereof. The preparation method comprises the following steps: (1) preparing the osmanthus fragrans extract; (2) a fermentation stage: mixing whole milk, cane sugar and the osmanthus fragrans extract to obtain a fermentation raw material, homogenizing, sterilizing, cooling, adding the composite leavening agent, uniformly stirring, sealing, and carrying out heat preservation fermentation to obtain solidified yoghourt; and (3) cold extraction stage: pouring the solidified yoghurt into gauze, refrigerating and hanging until the water content of the yoghurt is less than or equal to 25wt%, thereby obtaining the cold-extracted dry yoghurt. The cold-extracted dry dysphagia yoghurt disclosed by the invention is rich in fragrance and good in mouth feel, and a unique flavor level is created by combining the sweet flower fragrance of the sweet-scented osmanthus and the sour and sweet mouth feel of the yoghurt, so that brand-new taste enjoyment is brought to consumers.

Description

Technical Field

[0001] The invention belongs to the technical field of yogurt, and particularly relates to a cold-extracted dry yogurt and a preparation method thereof. Background Art

[0002] Cold-brewed yogurt is a type of yogurt made through a special process. It is a thick yogurt made by low-temperature fermentation and filtering the whey. It tastes similar to cheese, has high nutritional value and is suitable for a variety of combinations.

[0003] Osmanthus is known for its elegant and lasting fragrance. When this fragrance is incorporated into yogurt, it can add a complex aroma dimension to the yogurt, providing a fresh and unique flavor experience. With its elegant aroma and delicate taste, it has attracted many consumers who pursue novelty and high-quality food. However, studies have found that the active substances in osmanthus inhibit the activity of lactic acid bacteria and affect fermentation, resulting in low acetaldehyde content in yogurt. Acetaldehyde is one of the main flavor substances in fermented dairy products. Studies have found that acetaldehyde can give yogurt an aromatic flavor. In addition, the volatile aroma components (mainly linalool) in the osmanthus extracts currently used on the market are low, and because they will volatilize to a certain extent during the fermentation process, the osmanthus aroma is insufficient.

[0004] Therefore, there is an urgent need for a high-quality sweet-scented osmanthus-flavored cold-brewed dry yogurt and a preparation method thereof. Summary of the invention

[0005] The invention aims to provide a cold-extracted dry yogurt and a preparation method thereof.

[0006] In order to achieve the above object, the present invention provides the following technical solutions: A method for preparing cold-extracted dry yogurt comprises the following steps: (1) Preparation of osmanthus extract: fresh osmanthus, sucrose and water are mixed, heated, cooled to room temperature, and refrigerated to obtain a mixture; composite bacteria are added to the mixture, stirred evenly, and aerobic fermentation is carried out; after the fermentation is completed, the mixture is sterilized and filtered to obtain osmanthus juice; the osmanthus juice is concentrated under reduced pressure and freeze-dried to obtain osmanthus extract; (2) Fermentation stage: whole milk, sucrose and osmanthus extract are mixed to obtain fermentation raw materials, homogenized, sterilized and cooled, a composite fermentation agent is added, stirred evenly, sealed, and fermented at a temperature to obtain solidified yogurt; (3) Cold extraction stage: pour the solidified yogurt into gauze and hang it in the refrigerator until the water content of the yogurt is ≤25wt%, obtaining cold-extracted dry yogurt.

[0007] Preferably, the heating condition in step (1) is 90-100° C. for 5-10 min.

[0008] Preferably, the addition amount of the complex bacteria in step (1) is 10 6 -10 7 CFU / mL of the mixture.

[0009] Preferably, the complex bacteria in step (1) include Kluyveromyces marxianus, Trichoderma reesei and Aspergillus oryzae.

[0010] Preferably, the ratio of viable bacteria of Kluyveromyces marxianus, Trichoderma reesei and Aspergillus oryzae in the complex bacteria in step (1) is 10:(4 - 7):(13 - 16).

[0011] Preferably, the conditions for aerobic fermentation in step (1) are: aerobic fermentation at 25 - 30 °C for 10 - 15 days.

[0012] Preferably, the ventilation volume of air for aerobic fermentation is 0.6 - 0.8 cubic meters / (cubic meter * minute).

[0013] The osmanthus extract prepared by using the complex bacteria in the present invention has a high linalool content, and the osmanthus fragrance of the yogurt is more intense. At the same time, the osmanthus extract prepared by using the complex bacteria with a specific ratio in the present invention has a lower inhibitory effect on the production of acetaldehyde during yogurt fermentation, the content of acetaldehyde in the fermented yogurt is high, and the milk fragrance of the yogurt is more sufficient.

[0014] Preferably, the mass ratio of whole milk to osmanthus extract in step (2) is 100:(3 - 5).

[0015] Preferably, the complex starter in step (2) includes Lactococcus lactis, Lactobacillus paracasei and Lactobacillus gasseri.

[0016] Preferably, the weight ratio of Lactococcus lactis, Lactobacillus paracasei and Lactobacillus gasseri in step (2) is 1:(1.2 - 1.4):(0.4 - 0.7).

[0017] The present invention uses a complex starter to ferment yogurt, and the content of acetaldehyde in the obtained yogurt is high. At the same time, when using the complex starter of the present invention for fermentation, it is more conducive to retaining the aroma components in the osmanthus extract, and the osmanthus fragrance of the yogurt is more sufficient.

[0018] Preferably, the conditions for incubation fermentation in step (2) are: incubation fermentation at 25 - 30 °C for 15 - 20 h.

[0019] Preferably, the variety of osmanthus is Osmanthus fragrans 'Boyejingui' (species Latin name: Osmanthus fragrans 'Boyejingui').

[0020] The second aspect of the present invention provides the cold - extracted dry - curd yogurt prepared by the said preparation method.

[0021] Compared with the prior art, the advantages and beneficial effects of the present invention are: 1. The cold-brewed choke yogurt of the present invention not only retains the mellow taste of traditional yogurt, but also incorporates the aroma of osmanthus through innovative technology, achieving a breakthrough integration in flavor. The sweet floral fragrance of osmanthus complements the sour and sweet taste of yogurt, forming a unique flavor with distinct layers and a long aftertaste. This combination not only meets consumers' demand for healthy foods, but also enhances the sensory experience during consumption, especially in line with the trend of modern people pursuing high-quality life and personalized tastes, with broad market prospects. In addition, this product is suitable for a variety of consumption scenarios, such as breakfast accompaniment, afternoon leisure drink, or dessert substitute after meals, providing consumers with more diverse choices.

[0022] 2. By optimizing the formula and production process, the yogurt of the present invention significantly improves the storage stability of the product, effectively preventing the common water separation phenomenon (whey separation) during yogurt storage, thus ensuring that the product maintains a uniform and delicate texture and a stable taste during storage. This technical advantage not only extends the shelf life of the product, reduces the loss rate during transportation and sales, but also enhances consumers' trust in product quality. For production enterprises, this not only means higher production efficiency and lower costs, but also provides a solid technical guarantee for the large-scale promotion and long-distance sales of the product. Detailed implementation manners

[0023] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of them. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0024] The raw materials used in the following embodiments of the present invention are all commercially available products: The variety of osmanthus used in the following examples and comparative examples is Osmanthus fragrans 'Boyejingui' (Latin name).

[0025] The strains used in the present invention are purchased from the Hangzhou Branch of Wuhan Grey Algae Biotechnology Co., Ltd., and the specific product numbers are as follows: Aspergillus oryzae, product number HZB120226. Kluyveromyces marxianus, product number: HZB125979. Trichoderma reesei, product number: HZB120157, Lactococcus lactis, product number: HZB115944. Lactobacillus paracasei, product number: HZB118494, Lactobacillus gasseri, product number: HZB138217. Lactobacillus bulgaricus, product number: HZB116345. Lactobacillus helveticus, product number: HZB118100. Lactobacillus plantarum, product number: HZB129412. Saccharomyces cerevisiae, product number: HZB119506. Candida utilis, product number: HZB141179. Monascus purpureus, product number: HZB120244.

[0026] Example 1 This example provides a cold-extracted dry-curd yogurt and its preparation method, including the following steps: (1) Preparation of osmanthus extract: Mix fresh osmanthus, sucrose, and water in a mass ratio of 1:3:48, heat at 95 °C for 8 min, cool to room temperature, and then place at 4 °C for 22 h to obtain a mixture; add a compound bacteria to the mixture, and the addition amount of the compound bacteria is 5×10 6 CFU / mL of the mixture, stir evenly, and ferment aerobically at 27 °C for 12 days, with the ventilation rate of air being 0.7 cubic meters / (cubic meter * minute). The compound bacteria include Kluyveromyces marxianus, Trichoderma reesei, and Aspergillus oryzae, and the ratio of the viable bacteria of Kluyveromyces marxianus, Trichoderma reesei, and Aspergillus oryzae in the compound bacteria is 10:6:15; after fermentation, sterilize, filter with a 0.45 μm filter membrane to obtain osmanthus juice, and concentrate the osmanthus juice under reduced pressure at a pressure of 30 mbar and a temperature of 45 °C, and then freeze-dry to obtain osmanthus extract; (2) Fermentation stage: Mix whole milk, sucrose, and osmanthus extract in a mass ratio of 100:7:4 to obtain a fermentation raw material, homogenize at a rotation speed of 4200 r / min for 4 min, sterilize at a temperature of 95 °C for 5 min, cool to 22 °C after sterilization, and add a compound fermentation agent. The compound fermentation agent includes Lactococcus lactis, Lactobacillus paracasei, and Lactobacillus gasseri. The dosage of the compound fermentation agent is: add 1 g of the compound fermentation agent to 900 mL of milk, and the weight ratio of Lactococcus lactis, Lactobacillus paracasei, and Lactobacillus gasseri is 1:1.3:0.6; stir evenly, seal, and incubate at 23 °C for 18 h until the yogurt solidifies and no whey is separated out to obtain solidified yogurt; (3) Cold extraction stage: Pour the solidified yogurt into a gauze, place it in a 4 °C environment, and hang it until the water content of the yogurt is 20 wt% to obtain cold-extracted dry-curd yogurt.

[0027] Example 2 This embodiment provides a cold-extracted dry-swallow yogurt, and its preparation method includes the following steps: (1) Preparation of osmanthus extract: Mix fresh osmanthus, sucrose and water in a mass ratio of 1:2.8:45, heat at 100 °C for 5 min, cool to room temperature, and then place at 4 °C for 20 h to obtain a mixture; add a compound bacterium to the mixture, and the addition amount of the compound bacterium is 10 7 CFU / mL of the mixture, stir evenly, and ferment aerobically at 25 °C for 15 days, with the ventilation rate of air being 0.6 cubic meters / (cubic meter * minute). The compound bacterium includes Kluyveromyces marxianus, Trichoderma reesei and Aspergillus oryzae, and the ratio of the viable bacteria of Kluyveromyces marxianus, Trichoderma reesei and Aspergillus oryzae in the compound bacterium is 10:7:13; after fermentation, sterilize, filter with a 0.45 μm filter membrane to obtain osmanthus juice, and concentrate the osmanthus juice under reduced pressure at a pressure of 30 mbar and a temperature of 45 °C, and then freeze-dry to obtain osmanthus extract; (2) Fermentation stage: Mix whole milk, sucrose and osmanthus extract in a mass ratio of 100:7.5:5 to obtain a fermentation raw material, homogenize at a rotation speed of 4000 r / min for 5 min, sterilize at a temperature of 95 °C for 5 min, cool to 20 °C after sterilization, and add a compound ferment. The compound ferment includes Lactococcus lactis, Lactobacillus paracasei and Lactobacillus gasseri. The dosage of the compound fermentation agent is: 1 g of the compound fermentation agent is added to 1000 ml of milk, and the weight ratio of Lactococcus lactis, Lactobacillus paracasei and Lactobacillus gasseri is 1:1.2:0.7; stir evenly, seal, and incubate at 20 °C for 15 h until the yogurt solidifies and no whey separates out to obtain solidified yogurt; (3) Cold extraction stage: Pour the solidified yogurt into a gauze, place it in a 4 °C environment, and hang it until the water content of the yogurt is 20 wt% to obtain cold-extracted dry-swallow yogurt.

[0028] Example 3 This embodiment provides a cold-extracted dry-swallow yogurt, and its preparation method includes the following steps: (1) Preparation of osmanthus extract: Mix fresh osmanthus, sucrose and water in a mass ratio of 1:4:50, heat at 90 °C for 10 min, cool to room temperature, and then place at 2 °C for 25 h to obtain a mixture; add a compound bacterium to the mixture, and the addition amount of the compound bacterium is 10 6CFU / mL mixture, stir evenly, and ferment aerobically at 30°C for 10 days. The ventilation rate of air is 0.8 cubic meters / (cubic meter * minute). The composite bacteria include Kluyveromyces marxianus, Trichoderma reesei, and Aspergillus oryzae. The ratio of viable bacteria of Kluyveromyces marxianus, Trichoderma reesei, and Aspergillus oryzae in the composite bacteria is 10:4:16. After fermentation, sterilize and filter with a 0.45 μm filter membrane to obtain osmanthus juice. Concentrate the osmanthus juice under reduced pressure at a pressure of 30 mbar and a temperature of 45°C, and then freeze-dry to obtain osmanthus extract; (2) Fermentation stage: Mix whole milk, sucrose, and osmanthus extract with a mass ratio of 100:7.5:3 to obtain a fermentation raw material. Homogenize at a rotation speed of 4500 r / min for 3 min, sterilize at a temperature of 95°C for 5 min, cool to 25°C after sterilization, and add a composite fermentation agent. The composite fermentation agent includes Lactococcus lactis, Lactobacillus paracasei, and Lactobacillus gasseri. The dosage of the composite fermentation agent is: add 1 g of the composite fermentation agent to 800 mL of milk. The weight ratio of Lactococcus lactis, Lactobacillus paracasei, and Lactobacillus gasseri is 1:1.4:0.4; stir evenly, seal, and incubate at 25°C for 20 h until the yogurt solidifies and no whey separates out to obtain solidified yogurt; (3) Cold extraction stage: Pour the solidified yogurt into a gauze and place it in an environment at 4°C, hang it until the water content of the yogurt is 20 wt% to obtain cold-extracted dry-yogurt.

[0029] Comparative Example 1 The difference between this comparative example and Example 1 is that the weight ratio of Lactococcus lactis, Lactobacillus paracasei, and Lactobacillus gasseri is 0.6:1:1.3.

[0030] Comparative Example 2 The difference between this comparative example and Example 1 is that the composite fermentation agent is replaced with Lactobacillus bulgaricus, Lactobacillus helveticus, and Lactobacillus plantarum. The weight ratio of Lactobacillus bulgaricus, Lactobacillus helveticus, and Lactobacillus plantarum is 1:1.3:0.6.

[0031] Comparative Example 3 The difference between this comparative example and Example 1 is that the composite fermentation agent is replaced with Lactobacillus paracasei. Add 1 g of Lactobacillus paracasei to 900 mL of milk.

[0032] Comparative Example 4 The difference between this comparative example and Example 1 is that the composite fermentation agent includes Lactococcus lactis and Lactobacillus paracasei. The dosage of the composite fermentation agent is: add 1 g of the composite fermentation agent to 900 mL of milk. The weight ratio of Lactococcus lactis and Lactobacillus paracasei is 1:1.3.

[0033] Comparative Example 5 The difference between this comparative example and Example 1 is as follows: Preparation of osmanthus extract: Fresh osmanthus, sucrose and water were mixed at a mass ratio of 1:3:48, heated at 95 °C for 8 min, cooled to room temperature, and then placed at 4 °C for 22 h to obtain a mixture; the mixture was filtered through a 0.45 μm filter membrane to obtain osmanthus juice, and the osmanthus juice was concentrated under reduced pressure at a pressure of 30 mbar and a temperature of 45 °C, and freeze-dried to obtain osmanthus extract.

[0034] Comparative Example 6 The difference between this comparative example and Example 1 is that the composite bacteria include Kluyveromyces marxianus, Trichoderma reesei and Aspergillus oryzae, and the viable bacteria ratio of Kluyveromyces marxianus, Trichoderma reesei and Aspergillus oryzae in the composite bacteria is 15:10:6.

[0035] Comparative Example 7 The difference between this comparative example and Example 1 is that the composite bacteria are replaced with Aspergillus oryzae. The addition amount of Aspergillus oryzae is 5×10 6 CFU / mL of the mixture.

[0036] Comparative Example 8 The difference between this comparative example and Example 1 is that the composite bacteria include Kluyveromyces marxianus and Aspergillus oryzae, and the viable bacteria ratio of Kluyveromyces marxianus and Aspergillus oryzae in the composite bacteria is 10:15.

[0037] Comparative Example 9 The difference between this comparative example and Example 1 is that the composite bacteria include Saccharomyces cerevisiae, Candida utilis and Monascus ruber, and the viable bacteria ratio of Saccharomyces cerevisiae, Candida utilis and Monascus ruber is 10:6:15.

[0038] Performance test Perform performance tests on the cold-extracted dry-swallow yogurt prepared in Examples 1-3 and Comparative Examples 1-9.

[0039] 1. The determination method of acetaldehyde in cold-extracted dry-swallow yogurt refers to the method for determining the content of acetaldehyde in "The Influence of Acetaldehyde and Diacetyl Contents in Yogurt on Its Flavor" (Liu Ningning, Guo Hongmin, Ge Chunmei, Ma Kai), Section 2.2.3.

[0040] 2. Use a gas chromatography-mass spectrometry (GC-MS) instrument to determine the aroma components in the osmanthus extract. GC-MS analysis conditions: The gas chromatography conditions are a TR-5MS capillary chromatographic column (30 m × 0.25 mm × 0.25 μm); the programmed temperature rise is an initial temperature of 40 °C for 2 min, rising at 2 °C·min -1 to 60 °C, then rising at 5 °C·min -1 to 100 °C, and then rising at 10 °C·min -1 to 250 °C and holding for 5 min; the carrier gas is helium, and the helium flow rate is 1 mL·min-1 The split ratio is 10:1; the inlet temperature is 250 °C. The mass percentage content of linalool is statistically analyzed.

[0041] 3. Sensory evaluation: Twenty professional tasters were selected to conduct a sensory evaluation of the osmanthus aroma of all yogurts. The scoring method was used: integer scores from 0 to 10 were used, with higher scores indicating a more intense osmanthus aroma. The average value was then calculated.

[0042] 4. Stability: The yogurt was stored refrigerated at 4 °C for 3 months to observe whether water separated out.

[0043] The results are shown in Table 1.

[0044] Table 1 Performance test results As can be seen from Table 1, the acetaldehyde content of the cold-extracted dry-swallow yogurt in Examples 1-3 is high, the milk fragrance is stronger, the sensory evaluation is better, and the content of linalool, an aroma component in the osmanthus extract, is high, making the osmanthus flavor of the cold-extracted dry-swallow yogurt more intense.

[0045] For Comparative Examples 1-4, the composition of the compound fermentation starter used in fermentation is different, resulting in a low acetaldehyde content and poor stability of the cold-extracted dry-swallow yogurt.

[0046] In Comparative Example 5, the preparation method of the osmanthus extract is different, and in Comparative Examples 6-9, the compound bacteria used are different, resulting in a low content of aroma components in the osmanthus extract and a simultaneous reduction in the acetaldehyde content in the cold-extracted dry-swallow yogurt.

[0047] The above is the preferred embodiment of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A preparation method of cold-extracted choking yogurt, characterized in that, It includes the following steps: (1) Preparation of osmanthus extract: Mix fresh osmanthus, sucrose and water, heat, cool to room temperature, then refrigerate to obtain a mixture; add a compound bacterium to the mixture, stir evenly, carry out aerobic fermentation, after the fermentation ends, sterilize and filter to obtain osmanthus juice, concentrate the osmanthus juice under reduced pressure and freeze-dry to obtain osmanthus extract; (2) Fermentation stage: Mix whole milk, sucrose and osmanthus extract to obtain a fermentation raw material, homogenize, cool after sterilization, add a compound starter, stir evenly, seal and keep warm for fermentation to obtain coagulated yogurt; (3) Cold extraction stage: Pour the coagulated yogurt into a gauze and hang it in the refrigerator until the water content of the yogurt ≤ 25wt% to obtain cold-extracted dry curd yogurt.

2. The preparation method of the cold-extracted choking yogurt according to claim 1, characterized in that, The heating conditions in step (1) are: heating at 90 - 100°C for 5 - 10 min.

3. The preparation method of the cold-extracted choking yogurt according to claim 1, characterized in that, The compound bacterium in step (1) includes Kluyveromyces marxianus, Trichoderma reesei and Aspergillus oryzae.

4. The preparation method of the cold-extracted dry-swallow yogurt according to claim 3, characterized in that, The ratio of the viable bacteria of Kluyveromyces marxianus, Trichoderma reesei and Aspergillus oryzae in the compound bacterium in step (1) is 10:(4 - 7):(13 - 16).

5. The preparation method of the cold-extracted choking yogurt according to claim 4, characterized in that, The conditions for aerobic fermentation in step (1) are: aerobic fermentation at 25 - 30°C for 10 - 15 days.

6. The preparation method of the cold-extracted choking yogurt according to claim 1, characterized in that, The mass ratio of whole milk to osmanthus extract in step (2) is 100:(3 - 5).

7. The preparation method of the cold-extracted choking yogurt according to claim 1, characterized in that, The compound starter in step (2) includes Lactococcus lactis, Lactobacillus paracasei and Lactobacillus gasseri.

8. The preparation method of the cold-extracted choking yogurt according to claim 7, characterized in that, The weight ratio of Lactococcus lactis, Lactobacillus paracasei and Lactobacillus gasseri in step (2) is 1:(1.2 - 1.4):(0.4 - 0.7).

9. The preparation method of the cold-extracted choking yogurt according to claim 1, characterized in that, The conditions for keeping warm and fermenting in step (2) are: keeping warm and fermenting at 25 - 30°C for 7 - 10 h.

10. Cold-extracted dry curd yogurt prepared by the preparation method according to any one of claims 1 - 9.

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