Solidified yogurt added with North American plum-leaf crab polysaccharide and preparation method of solidified yogurt

Abstract

The invention belongs to the technical field of functional food, and particularly relates to set yogurt added with North American malus prunifolia fruit polysaccharide and a preparation method of the set yogurt. The preparation method comprises the following steps: firstly, adding North America crabapple polysaccharide efficiently extracted by an ultrasonic-enzymolysis composite extraction method into a yoghourt fermentation process, and then mixing the North America crabapple polysaccharide with pure milk, erythritol and gelatin for fermentation to prepare the set yoghourt of the North America crabapple polysaccharide. After solidification type yoghourt is fermented by adding different proportions of North American plum-leaf crab polysaccharide, the yoghourt fermentation effect is verified through a pH meter, a centrifugal machine, a texture analyzer, sensory evaluation and biological activity test. The functional yoghourt with special taste and texture is obtained by adding the North American malus prunifolia fruit polysaccharide under the condition of no sugar and zero food additive, the production cost is relatively low, more choices are provided for consumers, and the functional yoghourt has relatively high economic value and application value.

Description

Technical Field

[0001] The present invention belongs to the technical field of functional foods, and particularly relates to a set-type yogurt added with polysaccharides from Malus micromalus fruits and a preparation method thereof. Background Art

[0002] Yogurt is a dairy product made by fermenting milk, usually by the fermentation of lactic acid bacteria. During the fermentation process, lactic acid bacteria convert lactose in milk into lactic acid, which makes the milk sour and its texture thick. There are many advantages to drinking yogurt, especially in maintaining intestinal health, enhancing immunity, promoting nutrient absorption, etc. Yogurt is considered a very beneficial food.

[0003] Plant polysaccharides refer to macromolecular compounds synthesized by plant cells and composed of multiple sugar molecules linked by glycosidic bonds. They are widely present in plants and serve as energy storage materials, structural materials, or participate in the defense mechanisms of plants. Plant polysaccharides have good antioxidant, hypoglycemic and hypolipidemic, anti-inflammatory, radiation protection, anticoagulant, antiplatelet and other effects. Their applications in the food industry are also quite extensive. Many plant polysaccharides have gelling, thickening and stabilizing effects. For example, pectin, starch and alginate are widely used in the processing of foods such as jelly, jam, ice cream and beverages. Polysaccharides from Malus micromalus fruits have been verified through research to contain pyran rings, β-glycosidic bonds and α-glycosidic bonds, which are related to various biological metabolisms. It is a natural plant polysaccharide with multiple biological activities and has certain commercial utilization potential. For example, it can be used as a food improver for functional foods and can be made into antioxidant plant nutritional supplements, etc.

[0004] Functional yogurts usually add healthy ingredients such as probiotics, plant proteins, dietary fiber, low sugar, low fat, etc. to meet consumers' needs for healthy beverages. However, there are few choices of functional yogurts on the domestic market at present, and most of them add granulated sugar, sucrose and food additives. Without adding sugar and food additives, the present invention obtains a functional yogurt with a special taste and texture by adding polysaccharides from Malus micromalus fruits, providing more choices for consumers and being more in line with the development of the yogurt industry under the background of great health. Summary of the Invention

[0005] To solve the above problems, the present invention provides a functional set-type yogurt, and the main functional component includes polysaccharides from Malus micromalus fruits.

[0006] The technical solution adopted by the present invention is:

[0007] A set-type yogurt added with polysaccharides from Malus micromalus fruits, and the components of the set-type yogurt include polysaccharides from Malus micromalus fruits.

[0008] The preparation method of the above-mentioned set-style yogurt added with Malus micromalus fruit polysaccharide comprises the following steps: fresh normal-temperature pure milk → sugar adjustment → heating and homogenization → sterilization → cooling → inoculation of fermentation bacteria → addition of Malus micromalus fruit polysaccharide → fermentation → cold storage and ripening.

[0009] Further, in the above-mentioned preparation method, in the sugar adjustment step, the amounts of erythritol and gelatin added are 5 g / 100 mL and 1 g / 100 mL respectively.

[0010] Further, in the above-mentioned preparation method, the heating and homogenization step is: placing it in a water bath and heating to 50 - 70 °C, heating for 3 - 5 min, and then quickly homogenizing with a glass rod.

[0011] Further, in the above-mentioned preparation method, in the sterilization step, the fermentation glass bottles and glass rods are sterilized in boiling water for 10 - 15 min, and then the milk is pasteurized at 85 °C for 20 min.

[0012] Further, in the above-mentioned preparation method, in the cooling step, the pasteurized milk is cooled to 40 - 45 °C.

[0013] Further, in the above-mentioned preparation method, the fermentation bacteria are a mixed bacteria of Lactobacillus bulgaricus, Streptococcus thermophilus, Streptococcus acidophilus, Lactobacillus plantarum, and Lactobacillus casei.

[0014] Further, in the above-mentioned preparation method, in the step of adding Malus micromalus fruit polysaccharide, in a 100 mL fermentation glass bottle, Malus micromalus fruit polysaccharide is added at a mass-volume concentration of 1.0% - 2.5%.

[0015] Further, in the above-mentioned preparation method, the fermentation step is to place it in a constant-temperature environment of 42 °C and ferment statically for 8 - 10 h.

[0016] Further, in the above-mentioned preparation method, the cold storage and ripening step is to put the fermented yogurt into the refrigerator at 4 - 5 °C and ripen for 12 - 18 h.

[0017] The beneficial effects of the present invention are as follows: By adding polysaccharides from Malus micromalus fruits in different proportions, the pH is measured using a pH meter, the water-holding capacity is measured using a centrifuge, and a texture analyzer is used to determine the texture properties of the set yogurt products, including hardness, adhesiveness, draw length, elasticity, and cohesiveness. Twenty volunteers are recruited to conduct sensory evaluations on the set yogurt with different addition amounts. Finally, the biological activities of the set yogurt fermented with polysaccharides from Malus micromalus fruits are determined, including the DPPH free radical scavenging rate and hypoglycemic activity. Adding polysaccharides from Malus micromalus fruits to the yogurt fermentation process can not only significantly improve the application value of yogurt but also enhance its biological activity, making it more functionally valuable and meeting the market demands of specific consumer groups. Therefore, polysaccharides from Malus micromalus fruits have broad application prospects in functional yogurt, and this process technology has low costs and is easy to operate, with high economic value and application value. Description of the Drawings

[0018] Figure 1 It is a pH analysis diagram of set yogurt prepared with polysaccharides from Malus micromalus fruits in different proportions.

[0019] Figure 2 It is a water-holding capacity analysis diagram of set yogurt prepared with polysaccharides from Malus micromalus fruits in different proportions.

[0020] Figure 3 It is a hardness analysis diagram of set yogurt prepared with polysaccharides from Malus micromalus fruits in different proportions.

[0021] Figure 4 It is an adhesiveness analysis diagram of set yogurt prepared with polysaccharides from Malus micromalus fruits in different proportions.

[0022] Figure 5 It is a draw length analysis diagram of set yogurt prepared with polysaccharides from Malus micromalus fruits in different proportions.

[0023] Figure 6 It is an elasticity analysis diagram of set yogurt prepared with polysaccharides from Malus micromalus fruits in different proportions.

[0024] Figure 7 It is a cohesiveness analysis diagram of set yogurt prepared with polysaccharides from Malus micromalus fruits in different proportions.

[0025] Figure 8 It is a sensory evaluation analysis diagram of set yogurt prepared with polysaccharides from Malus micromalus fruits in different proportions.

[0026] Figure 9 It is a DPPH scavenging rate analysis diagram of set yogurt prepared with polysaccharides from Malus micromalus fruits in different proportions.

[0027] Figure 10 It is an α-amylase inhibition rate analysis diagram of set yogurt prepared with polysaccharides from Malus micromalus fruits in different proportions. Detailed Embodiments

[0028] Multiple embodiments of the present invention will be described in detail below. Unless otherwise specified, the methods used in the implementation process are conventional methods if not otherwise stated, and the reagents used are common reagents on the market or reagents prepared according to conventional methods. It should be noted that this description should not be regarded as a limitation of the present invention, but a more detailed elaboration of some aspects, characteristics and implementation schemes thereof.

[0029] Example 1 Preparation of Yogurt

[0030] 1) Preparation of polysaccharide from Malus micromalus fruits: Take fresh Malus micromalus fruits of the variety "Jinyan Huahong", wash them, freeze-dry them, powder them, take 30 g of the freeze-dried powder, carry out enzymatic hydrolysis under the conditions of a material-liquid ratio of 1:40 (g / mL), a compound enzyme addition amount of 4%, an enzymatic hydrolysis temperature of 50 °C, and an enzymatic hydrolysis time of 1 h, and inactivate at 95 °C for 5 min after enzymatic hydrolysis. Then continue to extract polysaccharides under the conditions of an ultrasonic power of 280 W, an ultrasonic time of 50 min, and an ultrasonic temperature of 45 °C. After the extraction is completed, centrifuge at 8000 r / min for 10 min, take the supernatant, then add 5% trichloroacetic acid to deproteinize and stir with a stirrer for 1 h, and then centrifuge at 8000 r / min for 10 min to collect the supernatant. Add 1.5% activated carbon powder for decolorization, centrifuge at 8000 r / min for 15 min after stirring for 30 min to take the supernatant. Concentrate the volume to 1 / 5 using a rotary evaporator, then add absolute ethanol at a ratio of 1:4, and carry out alcohol precipitation for 12 h. Then centrifuge to obtain the precipitate, appropriately add water, place it in a petri dish and freeze for 12 h, and freeze-dry it in a freeze-dryer to obtain polysaccharide from Malus micromalus fruits.

[0031] 2) Take 600 mL of Yili pure milk, add erythritol at 5 g / 100 mL and gelatin at 1 g / 100 mL, stir to dissolve, heat at 60 °C for 5 min, homogenize using a glass rod, sterilize the glass bottles, glass stirrers, etc. used with boiling water for 15 min, heat the milk to 85 °C for pasteurization, and keep it for 20 min. When cooled to 40 °C, add 1 g of yogurt fermentation powder (containing Lactobacillus bulgaricus, Streptococcus thermophilus, Streptococcus acidophilus, Lactobacillus plantarum, Lactobacillus casei), stir evenly and then sub-pack into sterilized 100 mL yogurt glass bottles, add 0%, 0.5%, 1.0%, 1.5%, 2.0%, 2.5% of constant weight polysaccharide from Malus micromalus fruits respectively and stir evenly, and place them in a constant temperature fermenter at 42 °C for fermentation for 10 h. After the fermentation is completed, place it in a 5 °C refrigerator and ripen for 15 h to obtain solidified yogurt with polysaccharide from Malus micromalus fruits.

[0032] Example 2 pH Measurement of Yogurt

[0033] The pH values of the set-type yogurt with Malus micromalus Makino polysaccharide at concentrations of 0%, 0.5%, 1.0%, 1.5%, 2.0%, and 2.5% were measured respectively. After fully stirring the ripened yogurt, it was measured using a pH meter.

[0034] According to Figure 1 It can be seen that as the addition amount of Malus micromalus Makino polysaccharide increases, the pH of the yogurt first decreases and then increases. The magnitude of pH often affects the sensory qualities and physicochemical properties of yogurt such as taste and texture. If the pH is too low, that is, the taste is too sour, it will affect the eating experience.

[0035] Determination of the water-holding capacity of the yogurt in Example 3

[0036] 20 g of the set-type yogurt with Malus micromalus Makino polysaccharide at concentrations of 0%, 0.5%, 1.0%, 1.5%, 2.0%, and 2.5% were respectively added to 50 mL centrifuge tubes, weighed, and then centrifuged at 8000 r / min for 10 min using a centrifuge to separate the supernatant. After pouring it out, it was weighed again.

[0037]

[0038] Among them, κ is the water-holding capacity, J1 is the weight after centrifugation, and J0 is the original weight.

[0039] The water-holding capacity is one of the important indicators for evaluating the quality of set-type yogurt. According to Figure 2 It can be seen that as the addition amount of Malus micromalus Makino polysaccharide increases, the water-holding capacity of the yogurt gradually increases, reaching the highest at a concentration of 1.5%, and then starts to decline. However, compared with the control group without addition, the water-holding capacity has increased. This is because the polysaccharide can cause a change in the protein conformation in the yogurt, form a protein gel, and increase the coagulability of the yogurt.

[0040] Analysis of the texture of the yogurt in Example 4

[0041] 20 g of the set-type yogurt with Malus micromalus Makino polysaccharide at concentrations of 0%, 0.5%, 1.0%, 1.5%, 2.0%, and 2.5% were respectively placed in the sample glass container of a TA-CT3 texture analyzer. The design parameters were: the cylindrical probe TA10 had a diameter of 12.7 mm, the test speed was 2.0 mm / s, the test distance was 20 mm, the surface trigger force was 5 g, and there were 2 cycles. The stirred yogurt was transferred to a 25 mL beaker. The hardness, adhesiveness, draw length, elasticity, and cohesiveness were calculated using Texture Exponent software.

[0042] According to Figures 3 to 7It can be seen that with the increase of the addition amount of Malus micromalus fruit polysaccharide, the hardness, adhesiveness, drawing length, elasticity and cohesiveness of yogurt first increase and then decrease. When the addition amount of Malus micromalus fruit polysaccharide is 1.5%, the hardness, adhesiveness, elasticity and cohesiveness of yogurt are the largest, which are 33±1 g, 13.33±0.58 g, 18.28±0.04 mm, 0.75±0.01 g·s respectively. When the addition amount is 2.0%, the drawing length of yogurt is the longest, which is 10.45±0.38 mm. This shows that the internal binding force of yogurt becomes larger at this time, the recovery effect is better when being squeezed, and the ability to maintain the gel state is stronger.

[0043] Example 5 Sensory Evaluation of Yogurt

[0044] In this experiment, the solidified yogurt prepared with different addition amounts will be subjected to sensory evaluation to obtain its optimal addition amount. The sensory evaluation standard table is shown in Table 1:

[0045] Table 1 Sensory Evaluation Standard Table

[0046]

[0047]

[0048] The final score is on a 100-point scale, color * 10%, smell * 10%, taste * 20%, texture * 20%, comprehensive score * 40%. In this experiment, 20 volunteers were invited to evaluate and score.

[0049] According to Figure 8 the scores, it can be known that the addition amount of Malus micromalus fruit polysaccharide hardly has an obvious impact on the color, indicating that the decolorization effect of Malus micromalus fruit polysaccharide is better during the extraction process. In terms of smell, with the increase of the addition amount of Malus micromalus fruit polysaccharide, the smell score gradually increases, and the impact on the smell is no longer obvious after reaching 1.0%. The taste and texture scores increase significantly with the increase of the addition amount, and the score of the solidified yogurt with an addition amount of 2.0% is the highest. The comprehensive score accounts for 40% in this sensory score. Generally speaking, the comprehensive score of 2.0% is the highest, and the trend is similar to that of the taste and texture scores. Finally, the yogurt with an addition amount of 2.0% wins, but the score of the yogurt with an addition amount of 1.5% is also close to that of the yogurt with an addition amount of 2.0%. It can be seen that due to the reasons of the volunteers themselves, some volunteers are also more inclined to give the highest score to the yogurt with an addition amount of 1.5%.

[0050] Example 6 Analysis of DPPH Scavenging Rate of Yogurt

[0051] Take 1 mL (or 1 g) of solidified yogurt containing Malus micromalus fruit polysaccharide at concentrations of 95% ethanol solution, 0%, 0.5%, 1.0%, 1.5%, 2.0%, and 2.5% respectively in test tubes, add deionized water, shake well and dilute 10 times. Then take 1 mL of each and mix it with 4 mL of 0.1 mmol / L DPPH-ethanol solution (prepared freshly before use), mix quickly and evenly, place it in the dark at room temperature and let it stand for 30 min, and use an ultraviolet spectrophotometer to measure the absorbance at 517 nm. Calculate the DPPH free radical scavenging rate according to the formula.

[0052]

[0053] Among them, μ is the DPPH free radical scavenging rate, L1 is the absorbance of the DPPH mixture of solidified yogurt with different concentrations of Malus micromalus fruit polysaccharide, and L0 is the absorbance of the mixture with 95% ethanol replacing the sample.

[0054] According to Figure 9 It can be seen that there is a sharp contrast between the solidified yogurt added with Malus micromalus fruit polysaccharide and the yogurt without addition. The DPPH scavenging rate of the yogurt without addition is only 19.39 ± 0.56%. With the addition of Malus micromalus fruit polysaccharide, the DPPH scavenging rate increases significantly and reaches 64.08 ± 0.88% at 2.5%.

[0055] Example 7 Analysis of α-amylase inhibition rate of yogurt

[0056] Take 1 mL (or 1 g) of solidified yogurt containing Malus micromalus fruit polysaccharide at concentrations of deionized water, 0%, 0.5%, 1.0%, 1.5%, 2.0%, and 2.5% respectively in test tubes, add deionized water, shake well and dilute 10 times. Then take 1 mL of each and mix it with 1 mL of α-amylase, shake well, react at 37 °C for 10 min, add 2 mL of 1% starch solution, react at 37 °C for 10 min, add 2 mL of 3,5-dinitrosalicylic acid (DNS) reagent, inactivate the enzyme at 95 °C for 6 min, add 10 mL of deionized water, and use an ultraviolet spectrophotometer to measure the absorbance at 540 nm after cooling. Calculate the α-amylase activity inhibition rate according to the formula.

[0057]

[0058] Among them, ξ is the α-amylase activity inhibition rate, P2 is the absorbance of the mixture of solidified yogurt with different concentrations of Malus micromalus fruit polysaccharide and enzyme and starch, P1 is the absorbance with deionized water replacing α-amylase, and P0 is the absorbance with deionized water replacing the sample.

[0059] According to Figure 10It can be seen that there is a sharp contrast between the set yogurt added with Malus micromalus fruit polysaccharide and the yogurt without addition. The α-amylase inhibition rate of the yogurt without addition is only 17.22±0.70%, and with the addition of Malus micromalus fruit polysaccharide, the α-amylase inhibition rate increases significantly, reaching 62.08±0.94% at 2.5%.

[0060] The above-described embodiments are only descriptions of the preferred embodiments of the present invention and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, various deformations and improvements made by those of ordinary skill in the art to the technical solutions of the present invention shall fall within the protection scope determined by the claims of the present invention.

Claims

1. A set-type yogurt added with Malus micromalus Makino fruit polysaccharide, characterized in that, The composition of the set yogurt includes Malus prunifolia polysaccharide.

2. The preparation method of a set-type yogurt added with Malus micromalus Makino fruit polysaccharide according to claim 1, characterized in that, It includes the following steps: fresh normal-temperature pure milk → sugar adjustment → heating and homogenization → sterilization → cooling → inoculation with fermentation bacteria → addition of Malus prunifolia polysaccharide → fermentation → cold storage and ripening.

3. The preparation method according to claim 2, characterized in that, In the step of sugar adjustment, the amounts of erythritol and gelatin added are 5 g / 100 mL and 1 g / 100 mL respectively.

4. The preparation method according to claim 2, characterized in that, The step of heating and homogenization is: placing it in a water bath and heating to 50 - 70 °C, heating for 3 - 5 min, and then quickly homogenizing with a glass rod.

5. The preparation method according to claim 2, wherein In the sterilization step, the fermentation glass bottles and glass rods are sterilized in boiling water for 10 - 15 min, and then the milk is pasteurized at 85 °C for 20 min.

6. The preparation method according to claim 2, characterized in that, In the cooling step, the pasteurized milk is cooled to 40 - 45 °C.

7. The preparation method according to claim 2, wherein, The fermentation bacteria is a mixed bacteria of Lactobacillus bulgaricus, Streptococcus thermophilus, Streptococcus acidophilus, Lactobacillus plantarum, and Lactobacillus casei.

8. The preparation method according to claim 2, wherein In the step of adding Malus prunifolia polysaccharide, in a 100 mL fermentation glass bottle, Malus prunifolia polysaccharide is added at a mass - volume concentration of 1.0% - 2.5%.

9. The preparation method according to claim 2, wherein The fermentation step is to place it in a constant - temperature environment of 42 °C and ferment statically for 8 - 10 h.

10. The preparation method according to claim 2, wherein, The cold storage and ripening step is to put the fermented yogurt into the refrigerator at 4 - 5 °C for after - ripening for 12 - 18 h.

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