A low oil phase emulsion gel fat substitute, low fat ice cream and method of making same

Abstract

This invention discloses a low-oil-phase emulsion gel fat substitute, low-fat ice cream, and its preparation method. The fat substitute is a low-oil-phase Pickering emulsion gel stabilized using bacterial cellulose nanofiber / soy protein isolate composite particles. Compared to the 5%–30% fat content of traditional commercial ice cream, this invention, by replacing cream with a low-oil-phase Pickering emulsion gel, reduces the fat content of the resulting ice cream to below 1.5%. Furthermore, this ice cream exhibits strong resistance to melting, good shape retention, and a texture similar to commercial products, demonstrating promising application and market prospects.

Description

Technical Field

[0001] This invention belongs to the field of food processing technology and relates to low oil phase Pickering emulsion gel and its use as a fat substitute in the preparation of low-fat ice cream. Background Technology

[0002] Ice cream is generally made from drinking water, dairy products, eggs, sugar, and edible vegetable oils. Fat is a significant component of ice cream, affecting its resistance to melting, shape retention, and smoothness during the freezing process. The current standard GB / T3114-2014 stipulates that all types of ice cream must contain at least 5% fat. Generally, commercial ice cream contains 10%–16% fat, and in actual production, to ensure optimal taste, the fat content can even reach 30%. High fat intake poses serious health risks, increasing the risk of obesity and metabolic diseases such as coronary heart disease. The food industry is searching for potential fat substitutes to reduce the fat content in ice cream. Currently, fat substitutes used in ice cream products include inulin, maltodextrin, polydextrose, milk protein, soy protein, dietary fiber, and starch; however, these substitutes can cause varying degrees of defects in the taste, texture, and flavor of ice cream.

[0003] Emulsion gels are emulsions with a gel-like network structure and solid-like mechanical properties, combining the advantages of both emulsions and hydrogels. They exhibit many beneficial properties in food processing and the delivery of bioactive ingredients, and have received widespread attention and application in improving food structure, reducing trans fats, and developing health foods. Among them, low-oil-phase emulsion gels (with an oil phase volume fraction generally below 30%) are suitable for direct consumption and help reduce various health problems caused by high-fat intake.

[0004] In the food industry, the preparation process of low-oil-phase emulsion gels involves two steps: first, emulsification to form an emulsion, and second, conversion of the liquid emulsion into a gel-like emulsion. Furthermore, due to the presence of excess particles in the continuous phase of the emulsion gel, sedimentation and flocculation easily occur, preventing long-term stability and limiting its applications. Therefore, exploring methods for preparing stable emulsion gels and simplifying the preparation process is urgently needed.

[0005] The high internal phase Pickering emulsion prepared by Chinese patent CN111205479A exhibits high stability, but the volume fraction of the internal phase vegetable oil exceeds 74%. Compared to this high internal phase emulsion with excellent rheological properties and stability (these properties are mainly determined by the high oil phase volume fraction; the higher the oil phase volume fraction, the more stable the emulsion gel and the stronger the gelling properties), achieving both low oil phase content and maintaining the emulsion in a gel state is not easy. Chinese patent CN107296260A adds hydrophilic colloids such as xanthan gum, konjac glucomannan, and low-methoxyl pectin, using a mixture of cellulose aqueous dispersion and hydrophilic colloids to form an emulsion gel, and then uses this emulsion gel to solidify the oil phase. However, after solidification, drying and dehydration are required, leading to a significant increase in the actual oil phase content (the oil content of oil gels is typically greater than 92%). Summary of the Invention

[0006] The purpose of this invention is to provide a low-oil-phase emulsion gel fat substitute, low-fat ice cream and its preparation method, so as to remove trans fatty acids and reduce saturated fatty acids in ice cream, thereby meeting people's pursuit of healthy eating and improving the quality of ice cream.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] A low-oil-phase emulsion gel fat substitute is a low-oil-phase Pickering emulsion gel stabilized using bacterial cellulose nanofibers (BCNs) / soy protein isolate (SPI) composite particles. In the low-oil-phase Pickering emulsion gel, the oil phase is 3% to 25% (e.g., 4% to 5%) of vegetable oil by volume, and the balance is an aqueous phase. The total concentration of SPI and BCNs in the aqueous phase (i.e., the concentration of the composite particles) ranges from 1% to 3%.

[0009] Preferably, the vegetable oil is selected from soybean oil, rapeseed oil, sunflower seed oil, peanut oil, or corn oil, etc.

[0010] Preferably, in the composite particles, the mass ratio of bacterial cellulose nanofibers to soy protein isolate is 15:1 to 10:1.

[0011] The preparation method of the above-mentioned low-oil-phase emulsion gel fat substitute includes the following steps:

[0012] Bacterial cellulose nanofibers (BCNs) / soy protein isolate (SPI) composite particles (aqueous phase) were mixed with vegetable oil (oil phase) at a volume ratio of 3 to 25:1, and then sheared at 10,000 to 20,000 rpm for 1 to 3 minutes to obtain a low-oil-phase Pickering emulsion gel.

[0013] Preferably, the preparation method of the bacterial cellulose nanofiber / soy protein isolate composite particle colloid specifically includes the following steps: mixing a bacterial cellulose nanofiber aqueous solution with a concentration of 0.08% to 0.15% and a soybean protein isolate ethanol aqueous solution with a concentration of 1% to 2% at a volume ratio of 2:1 to 3:1, then shearing and homogenizing, and then successively concentrating and centrifuging to obtain a bacterial cellulose nanofiber / soy protein isolate composite particle colloid with a concentration of 1% to 3%.

[0014] Preferably, the conditions for shearing and homogenization are: homogenizing at 5000-8000 rpm for 3-5 minutes using a high-speed shearing device.

[0015] Preferably, the concentration conditions (the main purpose of which is to remove ethanol) are as follows: the pressure of the rotary evaporator is 0.8 to 1.0 MPa, the rotation speed of the rotary evaporator is 90 to 110 rpm, the heating temperature of the rotary evaporator is 40 to 50°C, and the rotary evaporation time is 10 to 20 minutes.

[0016] Preferably, the centrifugation conditions (the main purpose of which is to remove water) are: the centrifuge speed is 3000-5000 rpm and the time is 10-20 minutes.

[0017] A low-fat ice cream comprising, by weight percentage: 40%–50% animal milk, 10%–40% of the aforementioned low-oil-phase emulsion gel fat substitute, 10%–20% sweetener, 5%–15% egg yolk, and 0%–20% heavy cream (the heavy cream having a fat content of 30%–40%).

[0018] Preferably, the sweetener is sucrose (e.g., white sugar).

[0019] Preferably, the animal milk is liquid milk derived from cows or sheep (e.g., sterilized cow's milk).

[0020] The above-mentioned method for preparing low-fat ice cream includes the following steps:

[0021] 1) Weigh out each raw material according to the proportion (e.g., sterilized milk, egg yolk, white sugar, light cream, low oil phase emulsion gel fat substitute);

[0022] 2) Mix the egg yolks, heavy cream, and low-oil-phase emulsion gel fat substitute, or mix the egg yolks and low-oil-phase emulsion gel fat substitute, and whip for 5-10 minutes. Then add animal milk (e.g., sterilized milk) and sweetener (e.g., white sugar) and continue whipping until dense bubbles are produced (e.g., whipping time 5-10 minutes) to obtain the mixture.

[0023] 3) Stir the mixture at 60–80°C for 15–30 minutes to obtain a mixed liquid (this step is equivalent to homogenization);

[0024] 4) The mixture is then subjected to heat sterilization (e.g., pasteurization), cooling, aging, and hardening to produce low-fat ice cream.

[0025] Preferably, the heat sterilization conditions are: sterilization at 80-100°C for 30-60 seconds.

[0026] Preferably, the cooling conditions are: 0 to 4°C.

[0027] Preferably, the aging conditions are as follows: the sterilized mixture is cooled to 20-25°C and then left to stand at 2-6°C for 4-8 hours.

[0028] Preferably, the hardening conditions are: standing at -18 to -20°C for 48 to 72 hours.

[0029] The beneficial effects of this invention are reflected in:

[0030] The fat substitute of the present invention is a low-oil-phase Pickering emulsion gel with physical properties similar to butter, including good rheological properties and stability. In food systems, it can simulate fat to produce a good lubrication and give food a good texture, thereby replacing solid fats in food systems, thereby reducing fat and calorie intake and helping to reduce the risk of obesity, metabolic diseases and cardiovascular diseases.

[0031] Furthermore, the low-oil-phase Pickering emulsion gel of the present invention contains a certain proportion of bacterial cellulose nanofibers / soy protein isolate composite particles, which can remain stable for a long time.

[0032] This invention provides a one-step emulsification method to form a low-oil-phase emulsion gel fat substitute with certain plasticity (making the low-oil-phase emulsion form a gel). This simplifies the traditional two-step process of low-oil-phase emulsion gel, reduces production time and cost, and does not produce trans fatty acids during its preparation, thus reducing the content of saturated fatty acids.

[0033] The low-fat ice cream of this invention uses a low-oil-phase Pickering emulsion gel to replace the cream in traditional commercial ice cream, reducing the fat content to below 1.5%. Moreover, while reducing the fat content of ice cream and avoiding the introduction of trans fatty acids, it also ensures that the ice cream has good anti-melting properties and stability. Thus, as a healthy low-fat ice cream with zero trans fatty acids and low saturated fatty acids, it meets the consumer demand for low-fat foods and the requirements for the healthy development of the food industry. Attached Figure Description

[0034] Figure 1 Flowchart of the production process for low-fat ice cream using low-oil-phase Pickering emulsion gel as a fat substitute.

[0035] Figure 2 The finished low-fat ice cream (yellow in appearance) was prepared by completely or partially replacing light cream with a 5% oil phase Pickering emulsion gel.

[0036] Figure 3 The stress dependence of the storage modulus (G') and loss modulus (G”) of the 5% oil phase Pickering emulsion gel, the viscosity of the 5% oil phase Pickering emulsion gel versus time (with constant shear stress), and the melting rate and sensory evaluation of low-fat ice cream prepared by completely and partially replacing cream with the 5% oil phase Pickering emulsion gel: 10%, 20%, and 30% emulsion (i.e., cream replacement rates of 10%, 20%, and 30%) represent the mass fraction (addition amount) of the 5% oil phase Pickering emulsion gel, respectively; the same lowercase letter between different groups indicates no significant difference, and different lowercase letters indicate significant differences. Detailed Implementation

[0037] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. The embodiments are only used to explain the present invention and are not intended to limit the scope of protection of the present invention.

[0038] Example 1

[0039] A low-fat ice cream prepared by replacing fat with a low-oil-phase emulsion gel, the preparation process of which is as follows (see...). Figure 1 ):

[0040] 1) Preparation of composite particle colloid: 1.25 g of SPI powder was dissolved in 100 mL of 70% ethanol aqueous solution (ethanol:water = 70:30, v / v) to obtain a 1.25% (w / v) SPI ethanol aqueous solution. 0.25 g of BCNs was dissolved in 250 mL of water to obtain a 0.1% BCNs aqueous solution. The BCNs aqueous solution and SPI ethanol aqueous solution were mixed at a volume ratio of 2.5:1 (BCNs aqueous solution:SPI ethanol aqueous solution = 2.5:1) and homogenized at 6000 rpm for 4 minutes using a high-speed homogenizer. Finally, excess ethanol and water were removed from the mixture by rotary evaporation (0.1 MPa, 100 rpm, 45℃, 10 minutes) and centrifugation (4000 rpm, 10 minutes) to obtain a 2% BCNs / SPI composite particle colloid (the remaining colloid is approximately 98% water).

[0041] 2) Preparation of low oil phase Pickering emulsion gel: 95 mL of BCNs / SPI composite particle colloid and 5 mL of soybean oil were mixed and sheared for 3 minutes under high-speed dispersion shearing at 20000 rpm to form a 5% oil phase Pickering emulsion gel.

[0042] 3) Preparation of low-fat ice cream: First, mix 10g egg yolks, 10g Pickering emulsion gel with 5% oil phase, and 20g heavy cream (35% fat content) at room temperature and whip for 5 minutes. Then add 45g sterilized milk and 15g granulated sugar and continue whipping until dense bubbles are produced. Stir the mixture with dense bubbles at 70℃ (water bath) for 20 minutes, then sterilize at 90℃ for 30 seconds. After sterilization, cool to 25℃ in an ice water bath, pour into round molds and age in a 4℃ refrigerator for 6 hours. Finally, harden and store in a -20℃ refrigerator for 72 hours to give the finished product a certain shape, thus obtaining low-fat ice cream with 10% low-oil phase emulsion gel. Figure 2 As shown.

[0043] Example 2

[0044] A low-fat ice cream prepared by replacing fat with a low-oil-phase emulsion gel is described below:

[0045] First, mix 10g of egg yolks, 20g of the 5% oil phase Pickering emulsion gel prepared in Example 1, and 10g of heavy cream (35% fat content) at room temperature and whip for 5 minutes. Then, add 45g of sterilized milk and 15g of granulated sugar and continue whipping until dense bubbles are produced. Stir the mixture with dense bubbles at 70°C for 20 minutes, then sterilize it by heating at 90°C for 30 seconds. After sterilization, cool it to 25°C in an ice water bath, then pour it into a round mold and age it in a 4°C refrigerator for 6 hours. Finally, harden and store it in a -20°C refrigerator for 72 hours to obtain a low-fat ice cream with 20% low oil phase emulsion gel. The finished product is shown below. Figure 2 As shown.

[0046] Example 3

[0047] A low-fat ice cream prepared by completely replacing fat with a low-oil-phase emulsion gel is described below:

[0048] First, mix 10g of egg yolks and 30g of the 5% oil-phase Pickering emulsion gel prepared in Example 1 at room temperature and beat for 5 minutes. Then, add 45g of sterilized milk and 15g of granulated sugar and continue beating until dense bubbles are produced. Stir the mixture with dense bubbles at 70°C for 20 minutes, then sterilize by heating at 90°C for 30 seconds. After sterilization, cool to 25°C in an ice water bath, then pour into a round mold and age in a 4°C refrigerator for 6 hours. Finally, harden and store in a -20°C refrigerator for 72 hours to obtain a low-fat ice cream with 30% low-oil-phase emulsion gel. The finished product is shown below. Figure 2 As shown.

[0049] like Figure 3 As shown, the prepared low-oil-phase emulsion gel (e.g., the 5% oil-phase Pickering emulsion gel prepared in Example 1) exhibits good gelation properties and high recovery properties, which is beneficial for mimicking some properties of solid fats (e.g., butter): producing a better lubricity and imparting a good texture to food. Simultaneously, it avoids the generation of trans fatty acids in traditional fat hardening processes (the reason why trans fatty acids are not formed during the preparation of emulsion gels includes: the vegetable oils such as soybean oil in the emulsion gel raw materials are simply emulsified to form a gel).

[0050] Furthermore, the 5% oil phase Pickering emulsion gel prepared by the above-mentioned composite colloidal particles exhibits strong stability, remaining intact even after 7 days at room temperature. The average particle size of the 5% oil phase Pickering emulsion gel after seven days of storage, measured using a laser particle size analyzer (LS13320, Beckman, US), was within the range of 25–35 μm, similar to the particle size of freshly prepared 5% oil phase Pickering emulsion gel.

[0051] Example 4

[0052] A low-fat ice cream made by replacing fat with composite particles, the preparation process of which is as follows:

[0053] 1) Preparation of composite particle colloid: 1.25 g of SPI powder was dissolved in 100 mL of 70% ethanol aqueous solution, and 0.25 g of BCNs was dissolved in 250 mL of water. The BCNs aqueous solution and SPI ethanol aqueous solution were mixed at a volume ratio of 2.5:1 and homogenized at 6000 rpm for 4 minutes using a high-speed homogenizer. Finally, excess ethanol and water in the mixture were removed by rotary evaporation (0.1 MPa, 100 rpm, 45℃, 10 minutes) and centrifugation (4000 rpm, 10 minutes) to obtain a 2% BCNs / SPI composite particle colloid.

[0054] 2) Preparation of low-fat ice cream: First, mix 10g egg yolks, 10g of 2% BCNs / SPI composite particle colloid, and 20g of light cream (35% fat content) at room temperature and whip for 5 minutes. Then, add 45g of sterilized milk and 15g of granulated sugar and continue whipping until dense bubbles are produced. Stir the mixture with dense bubbles at 70℃ for 20 minutes, then heat at 90℃ for 30 seconds to sterilize. After sterilization, cool to 25℃ in an ice water bath, then pour into round molds and age in a 4℃ refrigerator for 6 hours. Finally, harden and store in a -20℃ refrigerator for 72 hours to obtain low-fat ice cream with 10% composite particles. The finished product is shown below. Figure 2 As shown.

[0055] Example 5

[0056] A low-fat ice cream made by replacing fat with composite particles, the preparation process of which is as follows:

[0057] First, mix 10g of egg yolks, 20g of the BCNs / SPI composite particle colloid prepared in Example 4, and 10g of light cream (35% fat content) at room temperature and whip for 5 minutes. Then, add 45g of sterilized milk and 15g of granulated sugar and continue whipping until dense bubbles are produced. Stir the mixture with dense bubbles at 70°C for 20 minutes, then heat at 90°C for 30 seconds to sterilize. After sterilization, cool to 25°C in an ice water bath, pour into a round mold, and age in a 4°C refrigerator for 6 hours. Finally, harden and store in a -20°C refrigerator for 72 hours to obtain low-fat ice cream with 20% composite particles. The finished product is shown below. Figure 2 As shown.

[0058] Example 6

[0059] A low-fat ice cream made by replacing fat with composite particles, the preparation process of which is as follows:

[0060] First, mix 10g of egg yolks and 30g of the BCNs / SPI composite particle colloid prepared in Example 4 at room temperature and whisk for 5 minutes. Then, add 45g of sterilized milk and 15g of granulated sugar and continue whisking until dense bubbles are produced. Stir the mixture with dense bubbles at 70°C for 20 minutes, then sterilize by heating at 90°C for 30 seconds. After sterilization, cool to 25°C in an ice water bath, pour into a round mold, and age in a 4°C refrigerator for 6 hours. Finally, harden and store in a -20°C refrigerator for 72 hours to obtain a low-fat ice cream with 30% composite particles. The finished product is shown below. Figure 2 As shown.

[0061] The results are as follows Figure 3As shown, compared to ice cream with composite particle colloids replacing cream, ice cream with 5% emulsion gel (5% oil phase Pickering emulsion gel) replacing cream has a significantly lower melting rate (for example, Examples 2 and 5 both replaced 20% of the light cream).

[0062] Comparison Example

[0063] The traditional cream ice cream is prepared using the following process:

[0064] First, whisk 10g of egg yolks and 30g of heavy cream (35% fat) at room temperature for 5 minutes. Then, add 45g of sterilized milk and 15g of granulated sugar and continue whisking until fine, bubbly mixture is formed. Stir the bubbly mixture at 70°C for 20 minutes, then sterilize at 90°C for 30 seconds. After sterilization, cool to 25°C in an ice water bath. Pour the mixture into a round mold and age in a 4°C refrigerator for 6 hours. Finally, harden and store in a -20°C refrigerator for 72 hours. The finished product looks like... Figure 2 As shown.

[0065] like Figure 3 As shown in Table 1, the low-oil phase emulsion gel obtained by the present invention, as a fat substitute for low-fat ice cream (see Examples 1, 2, 3 and Control Examples), has fine and uniform crystals, strong resistance to melting, good shape retention (direct observation) and viscoelasticity.

[0066] Table 1. Texture analysis of low-fat ice cream prepared by replacing cream with 5% emulsion gel.

[0067]

[0068] The present invention has the following advantages:

[0069] 1) This invention prepares a low-oil-phase emulsion gel through a one-step emulsification method, which has the advantages of both emulsions and hydrogels, exhibiting many beneficial properties in food structure; and the one-step method reduces production time, difficulty and cost, which is conducive to its application as a fat substitute in the food industry.

[0070] 2) The low-oil phase emulsion gel prepared by this invention can simulate some properties of solid fats in food systems, thereby replacing some of the fats in the food system and avoiding the generation of trans fatty acids in traditional fat hardening processes. To a certain extent, it can reduce various health problems caused by high oil, high saturated fatty acids and trans fatty acid intake.

[0071] 3) The low-oil phase emulsion gel obtained by this invention, as a fat substitute, significantly reduces the fat content of traditional commercial ice cream from 5% to 30% to below 1.5%, reducing fat energy intake, which is beneficial for preventing and alleviating the problems of many chronic diseases such as hyperlipidemia and obesity.

[0072] 4) The low-oil phase emulsion gel obtained by this invention is a low-fat ice cream product that is a fat substitute. Its color, aroma, taste and texture are similar to those of commercial products. It can also remain stable after being stored at -20°C for 6 months, which can meet the needs of the public for ice cream products and is comparable to traditional high-fat ice cream.

Claims

1. A low-fat ice cream, characterized in that: The ice cream comprises the following components by weight percentage: 40%–50% animal milk, 10%–40% low-oil-phase emulsion gel fat substitute, 10%–20% sweetener, 5%–15% egg yolk, and 0%–20% heavy cream; the low-oil-phase emulsion gel fat substitute is a low-oil-phase Pickering emulsion gel stabilized by bacterial cellulose nanofiber / soy protein isolate composite particle colloid; in the low-oil-phase Pickering emulsion gel, the oil phase is 4%–5% by volume of vegetable oil, and the remainder is an aqueous phase, which is bacterial cellulose nanofiber / soy protein isolate composite particle colloid; The preparation method of the bacterial cellulose nanofiber / soy protein isolate composite particle colloid specifically includes the following steps: mixing a bacterial cellulose nanofiber aqueous solution with a concentration of 0.08%~0.15% and a soybean protein isolate ethanol aqueous solution with a concentration of 1%~2% at a volume ratio of 2:1~3:1, then shearing and homogenizing, and then successively concentrating and centrifuging to obtain a bacterial cellulose nanofiber / soy protein isolate composite particle colloid with a concentration of 1%~3%; The preparation method of the low-oil-phase Pickering emulsion gel includes the following steps: mixing bacterial cellulose nanofiber / soy protein isolate composite particles with vegetable oil at a volume ratio of 3~25:1, and then shearing at 10000~20000 rpm for 1~3 minutes to obtain the low-oil-phase Pickering emulsion gel.

2. The low-fat ice cream according to claim 1, characterized in that: The conditions for shearing and homogenization are: homogenization at 5000~8000 rpm for 3~5 min using a high-speed shearing device.

3. The low-fat ice cream according to claim 1, characterized in that: The concentration conditions are as follows: the pressure of the rotary evaporator is 0.1 MPa, the rotation speed of the rotary evaporator is 100 rpm, the heating temperature of the rotary evaporator is 45 ℃, and the rotary evaporation time is 10 minutes.

4. The low-fat ice cream according to claim 1, characterized in that: The centrifugation conditions are: centrifuge speed of 3000~5000 rpm, time of 10~20 minutes.

5. The low-fat ice cream according to claim 1, characterized in that: The sweetener is sucrose; the animal milk is liquid milk derived from cows or sheep.

6. A method for preparing low-fat ice cream as described in claim 1, characterized in that: Includes the following steps: The egg yolks, heavy cream, and low-oil-phase emulsion gel fat substitute are mixed, or the egg yolks and low-oil-phase emulsion gel fat substitute are mixed. After mixing, the mixture is whipped for 5-10 minutes, then animal milk and sweetener are added and whipped again until dense bubbles are produced to obtain a mixture. The mixture is stirred at 60-80 ℃ for 15-30 minutes to obtain a liquid mixture. The liquid mixture is then subjected to heat sterilization, cooling, aging, and hardening to obtain low-fat ice cream.

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