Low-calorie high-oxidation-stability shortening base oil and preparation method thereof

Abstract

The invention belongs to the technical field of shortening preparation, and particularly relates to shortening base oil with low calorie and high oxidation stability and a preparation method of the shortening base oil. According to the preparation method of the shortening base oil with low calorie and high oxidation stability, provided by the invention, the novel shortening base oil with high oxidation stability, zero trans form, low cholesterol and low calorie is produced by taking palm stearin, cyperus esculentus oil and medium-carbon-chain triacylglycerol oil as raw materials and taking immobilized lipase Lipozyme RMIM as a catalyst; the problems that existing shortening is poor in oxidation stability, high in cholesterol content, excessive in trans-fatty acid content and high in long-carbon-chain saturated fatty acid content can be solved, and the low-calorie high-nutrition high-quality shortening has extremely wide application prospects in the field of preparation of low-calorie high-nutrition high-quality shortening.

Description

Technical Field

[0001] The invention belongs to the technical field of shortening preparation, and particularly relates to a shortening base oil with low calorie content and high oxidation stability and a preparation method thereof. Background Art

[0002] Shortening is a type of fat product that first appeared as a substitute for lard. It means that using this type of fat in baked food processing can make the product very crispy, so the fat with this property is called "shortening". With the development of society, people's living standards continue to improve, and the market demand for shortening is also expanding.

[0003] 99% of shortening is base oil, and the remaining 1% is other food additives such as emulsifiers. Therefore, shortening base oil has a crucial impact on the properties of shortening. At present, common shortening base oils are mainly refined animal and vegetable oils and hydrogenated vegetable oils or mixtures of the above oils, which inevitably have problems such as high cholesterol content, excessive trans fatty acid content, high long-chain saturated fatty acid content and poor nutritional value. Long-term consumption may increase the obesity rate of the population and the incidence of a series of diseases caused by obesity. In addition, the common shortening base oils on the market are also prone to problems such as poor oil compatibility and easy oxidation and deterioration. During storage, they are also prone to problems such as oil deterioration, oil seepage, and sanding, which have an adverse effect on the application quality of shortening.

[0004] Therefore, there is an urgent need to develop a new type of shortening base oil that is zero-trans, low in cholesterol, low in calories, nutritious and healthy, not prone to sanding, and has good oxidative stability to meet the diverse market demands and consumers' demand for high-quality shortening. Summary of the invention

[0005] In view of the above problems, one of the objects of the present invention is to provide a method for preparing a shortening base oil with low calorie and high oxidative stability. The method uses palm stearin, cyperus oleifera oil and medium-chain triglyceride oil as raw materials and immobilized lipase LipozymeRMIM as a catalyst to prepare a novel shortening base oil with zero trans, low cholesterol, low calorie, nutrition and health, not easy to sand, and good oxidative stability, thereby meeting the use requirements of high-quality shortening.

[0006] The second object of the present invention is to provide a shortening base oil with low calorie content and high oxidation stability prepared by the above preparation method.

[0007] To achieve the above object, the technical solution adopted by the present invention is:

[0008] A method for preparing a shortening base oil with low calorie content and high oxidation stability comprises the following steps:

[0009] The palm stearin, cyperus oleifera oil and medium-chain triglyceride oil are uniformly mixed to obtain a mixed oil; immobilized lipase Lipozyme RMIM is added to the mixed oil to carry out an ester exchange reaction, and then purified to obtain a shortening base oil with low heat and high oxidation stability;

[0010] Among them, in the mixed oil, the mass ratio of palm stearin, cyperus oleifera oil and medium-chain triglyceride oil is (55-65): (15-20): (20-25); in the fatty acid composition of the palm stearin, the content of long-chain saturated fatty acids is ≥58%; in the fatty acid composition of the cyperus oleifera oil, the content of oleic acid is ≥65%; in the fatty acid composition of the medium-chain triglyceride oil, the content of medium-chain fatty acids is ≥95%.

[0011] As a preferred solution, in the fatty acid composition of the palm stearin, the content of palmitic acid is 54% to 60%, the content of oleic acid is 28% to 33%, the content of linoleic acid is 5% to 8%, and the content of stearic acid is 4% to 7%.

[0012] As a preferred solution, in the fatty acid composition of the jatropha oil, the content of oleic acid is 65% to 80%, the content of palmitic acid is 10% to 15%, and the content of linoleic acid is 6% to 14%.

[0013] As a preferred solution, in the fatty acid composition of the medium-chain triglyceride oil, the content of caprylic acid is 52% to 55%, and the content of capric acid is 43% to 48%.

[0014] Palm stearin has a high melting point. In order to maintain the uniformity of the preparation of the mixed oil, as a preferred solution, when preparing the mixed oil, palm stearin is pre-heated at 70-80°C to melt, and then mixed evenly with cyperus oleifera oil and medium-chain triglyceride oil.

[0015] As a preferred solution, the added mass of the immobilized lipase Lipozyme RMIM is 5% to 9% of the mixed oil.

[0016] As a preferred solution, the temperature of the transesterification reaction is 60-70° C., and the time of the transesterification reaction is 2-4 hours.

[0017] As a further preferred solution, the transesterification reaction is carried out under vacuum conditions. Specifically, before adding the immobilized lipase Lipozyme RMIM, the mixed oil system is first evacuated, and then the transesterification reaction is carried out while maintaining the vacuum state.

[0018] As a preferred solution, the purification process is: after the transesterification reaction is completed, the immobilized lipase Lipozyme RMIM is first separated, and then alcohol washing and vacuum desolventizing are performed in sequence.

[0019] As a preferred solution, the solvent used in the alcohol washing is ethanol; the temperature of the vacuum desolventizing treatment is 50-60°C. Further preferably, the vacuum degree of the vacuum desolventizing treatment is 0-200 mbar. The present invention does not specifically limit the time of vacuum desolventizing, and the technicians can adjust the desolventizing time according to the amount of solvent.

[0020] A shortening base oil with low calorie content and high oxidation stability prepared by the preparation method.

[0021] The technical solution of the present invention has the following beneficial effects:

[0022] The method for preparing shortening base oil provided by the present invention uses palm stearin, cyperus oleifera oil and medium-chain triglyceride oil as raw materials and immobilized lipase Lipozyme RMIM as a catalyst to prepare shortening base oil, and has the advantages that:

[0023] 1) The present invention uses plant-based raw material oil to ensure that the cholesterol content in the base oil is at a low level. At the same time, the present invention uses an ester exchange reaction to prepare shortening, which changes the triglyceride composition at the molecular level to change the melting properties of the oil, does not change the fatty acid composition of the oil, and does not produce trans fatty acids. Therefore, the preparation method of the present invention can reduce the cholesterol content and avoid the production of trans fatty acids.

[0024] 2) The shortening base oil produced by the present invention is produced by transesterification, and compared with physically mixed shortening, the compatibility of the shortening base oil is better, and the problems of product degradation, oil leakage, and sanding are not likely to occur.

[0025] 3) The present invention uses the immobilized enzyme Lipozyme RMIM to catalyze the transesterification reaction. In the process of using the lipase to produce shortening, the present invention finds that it has a wide temperature and pH range of action and has extremely high catalytic activity. In particular, the present invention confirms through experiments that the immobilized enzyme Lipozyme RMIM can effectively catalyze the transesterification reaction of palm stearin, safflower oil and medium-chain triglyceride oil, so that its transesterification product presents a special solid fat content (SFC) curve, effectively meeting the application standard of shortening for SFC. At the same time, the price of the immobilized enzyme Lipozyme RMIM is lower than that of other immobilized enzymes. After the reaction is completed, it can be separated from the product by filtration, which is convenient and fast, and can be recycled and reused many times, which is conducive to reducing production costs. In addition, the crude product prepared by the catalytic transesterification of the immobilized enzyme Lipozyme RMIM has a low acid value, is easy to separate and purify, avoids the problem of high acid value of the product caused by the catalytic transesterification reaction of the liquid enzyme, and can save production costs.

[0026] 4) Among the raw material oils used in the present invention, cyperus oleic acid oil is a new high oleic acid type oil, and its application in shortening has not been seen yet. The present invention applies cyperus oleic acid oil to the production of shortening base oil for the first time, broadens the application range of cyperus oleic acid oil in the field of deep processing of oils and fats, and provides strong technical support for its application in special oils such as shortening.

[0027] 5) The shortening base oil prepared by the present invention has a sliding melting point between 35 and 40°C, which meets the shortening melting point standard. 20℃ The SFC is 20% to 32%, which can provide good plasticity at room temperature and facilitate product shaping. 35℃ The shortening base oil prepared by the present invention after esterification has good processing and edible properties.

[0028] 6) In the shortening base oil prepared by the present invention, oleic acid accounts for about 90% of the unsaturated fatty acid content in the fatty acid composition, which is beneficial to improving the nutritional value of shortening. At the same time, the content of medium- and long-chain triglycerides formed by the combination of medium-chain fatty acids and long-chain fatty acids on triglycerides reaches more than 50%. Medium- and long-chain triglycerides can provide energy to the human body quickly and steadily, and are not easy to cause fat accumulation, which is beneficial to reducing the obesity rate of the population and the incidence of a series of diseases caused by obesity, and is of great benefit to human health, and is more in line with the development demand for low-calorie and high-nutrition shortening in the industry.

[0029] 7) The shortening base oil prepared by the present invention has excellent oxidation stability, and its oxidation induction period is 5.1 times that of the shortening base oil prepared from sunflower seed oil and 6.2 times that of the shortening base oil prepared from linseed oil. Higher oxidation stability is conducive to reducing the oxidation deterioration of shortening during baking and storage, and improving the edible quality and shelf life of baked products.

[0030] Therefore, the present invention uses palm stearin, jatropha oil and medium-chain triglyceride oil as raw materials and uses immobilized lipase Lipozyme RMIM as a catalyst to produce shortening base oil that is zero-trans, low in cholesterol, low in calories, has good processing and edible properties and excellent oxidative stability, comprehensively solves the problems of poor oxidative stability of shortening, high cholesterol content, excessive trans fatty acids and high long-chain saturated fatty acid content, and has extremely broad application prospects in the field of preparation of low-calorie, high-nutrition and high-quality shortening. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1The SFC comparison results of the shortening base oil (EIE) and the physical mixed oil (PB) of Example 3 of the present invention are shown;

[0032] Figure 2 The XRD crystal analysis results of the shortening base oil (EIE) and the physical mixed oil (PB) of Example 3 of the present invention, the raw material palm stearin (PSt), and the commercial shortening (CS);

[0033] Figure 3 The thermal property analysis results of shortening base oil (EIE) and physical mixed oil (PB) of Example 3 of the present invention, raw palm stearin (PSt), and commercial shortening (CS);

[0034] Figure 4 It is a comparison diagram of the SFC curves of the shortening base oil (PSt:TNO:MCTO) of Example 3 of the present invention, the shortening base oil prepared from sunflower seed oil and palm stearin (PSt:SFO), and the shortening base oil prepared from linseed oil and palm stearin (PSt:LSO). DETAILED DESCRIPTION

[0035] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention will be clearly and completely described below in conjunction with specific embodiments. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. The test methods used in the following embodiments are conventional methods unless otherwise specified; the raw materials used are all commonly used in the field, available to the public or commercially available, unless otherwise specified.

[0036] In the embodiments of the present invention, the reagents used are commercially available chemically pure or analytically pure. In the following examples and comparative examples of the present invention, the immobilized lipase Lipozyme RMIM, liquid lipase CALB, and immobilized lipase Novozym 435 used are from the Novozymes brand. Sodium methoxide was purchased from Tianjin Damao Chemical Reagent Factory. Pichia pastoris liquid lipase was purchased from Wuhan Yuancheng Technology Development Co., Ltd.

[0037] The present invention provides a method for preparing a shortening base oil with low calorie content and high oxidation stability, comprising the following steps:

[0038] The palm stearin, cyperus oleifera oil and medium-chain triglyceride oil are uniformly mixed to obtain a mixed oil; immobilized lipase Lipozyme RMIM is added to the mixed oil to carry out an ester exchange reaction, and then purified to obtain a shortening base oil with low heat and high oxidation stability;

[0039] Among them, in the mixed oil, the mass ratio of palm stearin, cyperus oleifera oil and medium-chain triglyceride oil is (55-65): (15-20): (20-25); in the fatty acid composition of the palm stearin, the content of long-chain saturated fatty acids is ≥58%; in the fatty acid composition of the cyperus oleifera oil, the content of oleic acid is ≥65%; in the fatty acid composition of the medium-chain triglyceride oil, the content of medium-chain fatty acids is ≥95%.

[0040] In the present invention, the type of raw oil and its fatty acid composition, the raw oil ratio, and the type of lipase are key parameters. The present invention specially selects three specific types of oils and fats with special fatty acid compositions (palm stearin, jatropha oil, and medium-chain triglyceride oil), performs transesterification reaction under a specific ratio (55-65:15-20:20-25) and the catalysis of a special immobilized lipase (Lipozyme RMIM), thereby preparing for the first time a novel shortening base oil with zero trans, low cholesterol, low calories, nutrition and health, not easy to sand, and good oxidation stability.

[0041] Furthermore, the present invention does not specifically limit the specific fatty acid composition of palm stearin, cyperus oleiferus oil and medium-chain triglyceride oil. In different embodiments, technicians can select the above-mentioned raw material oil from different commercial channels, or prepare the raw material oil by themselves according to the standard preparation method of oil. The characteristic fatty acid composition of the selected raw material oil product only needs to meet the basic requirements defined in the present invention that "the content of long-chain saturated fatty acids in the fatty acid composition of palm stearin is ≥58%; the content of oleic acid in the fatty acid composition of cyperus oleiferus oil is ≥65%; the content of medium-chain fatty acids in the fatty acid composition of medium-chain triglyceride oil is ≥95%", and they can all achieve the preparation effect of shortening base oil equivalent to the present invention.

[0042] In order to further improve the performance of shortening and enhance the oxidative stability of shortening, it is further preferred that the fatty acid composition of palm stearin includes 54% to 60% palmitic acid, 28% to 33% oleic acid, 5% to 8% linoleic acid, and 4% to 7% stearic acid. The fatty acid composition of jatropha oil includes 65% to 80% oleic acid, 10% to 15% palmitic acid, and 6% to 14% linoleic acid. The fatty acid composition of medium-chain triglyceride oil includes 52% to 55% caprylic acid, and 43% to 48% capric acid.

[0043] More specifically, in the following embodiments of the present invention, the transesterified raw materials palm stearin, cyperus oleiferus oil and medium-chain triglyceride oil are all from commercial channels. Palm stearin (melting point 50°C) is from Yihai Grain and Oil Industry Co., Ltd., cyperus oleiferus oil is from Xinjiang Sanli Grain and Oil Co., Ltd., and medium-chain triglyceride oil is from Guangzhou Shengtong Trading Co., Ltd. The fatty acid composition of each raw material oil detected by gas chromatography is shown in Table 1. Among them, "ND" means not detected.

[0044] Table 1. Fatty acid composition of the transesterified feedstock oil of the present invention

[0045]

[0046] As shown in Table 1, palm stearin, jatropha oil and medium-chain triglyceride oil all have their characteristic fatty acid compositions. Among them, palm stearin is rich in long-chain saturated fatty acids, with a content of more than 58%, especially palmitic acid, which has the highest content. Jatropha oil is rich in oleic acid, with a content of more than 65%; medium-chain triglyceride oil is rich in caprylic acid and capric acid, two medium-chain fatty acids, with a total content of more than 95%.

[0047] 1. Implementation

[0048] Example 1

[0049] This embodiment provides a shortening base oil with low calorie content and high oxidative stability, and the preparation method thereof comprises the following steps:

[0050] Take 55g of palm stearin in a round-bottom flask, melt it at 75°C, add 20g of jatropha oil and 25g of medium-chain triglyceride oil to obtain a ternary mixed oil. Evacuate the round-bottom flask, then add 5g of immobilized lipase Lipozyme RMIM to the ternary mixed oil, and carry out ester exchange reaction under vacuum. The ester exchange reaction conditions are: reaction temperature 60°C, reaction time 3h. After the ester exchange reaction is completed, the immobilized lipase Lipozyme RMIM is separated, and then the obtained crude shortening base oil is washed with ethanol and desolventized by vacuum rotary evaporation (temperature 50-60°C) to obtain the shortening base oil with low heat and high oxidation stability of this embodiment.

[0051] Example 2

[0052] This embodiment provides a shortening base oil with low calorie content and high oxidative stability, and the preparation method thereof comprises the following steps:

[0053] Take 65g of palm stearin in a round-bottom flask, melt it at 75°C, add 15g of cyperus oleifera oil and 20g of medium-chain triglyceride oil to obtain a ternary mixed oil. Evacuate the round-bottom flask, then add 7g of immobilized lipase Lipozyme RMIM to the ternary mixed oil, and carry out ester exchange reaction under vacuum. The ester exchange reaction conditions are: reaction temperature 65°C, reaction time 2h. After the ester exchange reaction is completed, the immobilized lipase Lipozyme RMIM is separated, and then the obtained crude shortening base oil is washed with ethanol and desolventized by vacuum rotary evaporation (temperature 50-60°C) to obtain the shortening base oil with low heat and high oxidation stability of this embodiment.

[0054] Example 3

[0055] This embodiment provides a shortening base oil with low calorie content and high oxidative stability, and the preparation method thereof comprises the following steps:

[0056] Take 65g of palm stearin in a round-bottom flask, melt it at 75°C, add 15g of cyperus oleifera oil and 20g of medium-chain triglyceride oil to obtain a ternary mixed oil. Evacuate the round-bottom flask, then add 9g of immobilized lipase Lipozyme RMIM to the ternary mixed oil, and carry out ester exchange reaction under vacuum. The ester exchange reaction conditions are: reaction temperature 65°C, reaction time 3h. After the ester exchange reaction is completed, the immobilized lipase Lipozyme RMIM is separated, and then the obtained crude shortening base oil is washed with ethanol and desolventized by vacuum rotary evaporation (temperature 50-60°C) to obtain the shortening base oil with low heat and high oxidation stability of this embodiment.

[0057] Example 4

[0058] This embodiment provides a shortening base oil with low calorie content and high oxidative stability, and the preparation method thereof comprises the following steps:

[0059] Take 65g of palm stearin in a round-bottom flask, melt it at 85°C, add 15g of cyperus oleifera oil and 20g of medium-chain triglyceride oil to obtain a ternary mixed oil. Evacuate the round-bottom flask, then add 5g of immobilized lipase Lipozyme RMIM to the ternary mixed oil, and carry out ester exchange reaction under vacuum. The ester exchange reaction conditions are: reaction temperature 65°C, reaction time 4h. After the ester exchange reaction is completed, the immobilized lipase Lipozyme RMIM is separated, and then the obtained crude shortening base oil is washed with ethanol and desolventized by vacuum rotary evaporation (temperature 50-60°C) to obtain the shortening base oil with low heat and high oxidation stability of this embodiment.

[0060] 2. Comparison

[0061] Comparative Example 1

[0062] The comparative example provides a shortening base oil, and the preparation method thereof comprises the following steps:

[0063] Take 65g of palm stearin in a round-bottom flask, melt it at 85°C, add 15g of cyperus oleifera oil and 20g of medium-chain triglyceride oil to obtain a ternary mixed oil. Evacuate the round-bottom flask, then add 0.7g of chemical catalyst sodium methoxide to the ternary mixed oil, and perform an ester exchange reaction under vacuum. The ester exchange reaction conditions are: reaction temperature 105°C, reaction time 30min. After the ester exchange reaction is completed, wash and remove soap and vacuum dehydration (vacuum dehydration temperature is 95°C, vacuum degree is 0.09-0.1Mpa) are carried out to obtain the shortening base oil of this comparative example.

[0064] Comparative Example 2

[0065] The comparative example provides a shortening base oil, and the preparation method thereof comprises the following steps:

[0066] Take 65g of palm stearin in a round-bottom flask, melt it at 80℃, add 15g of cyperus oleifera oil and 20g of medium-chain triglyceride oil to obtain a ternary mixed oil. Evacuate the round-bottom flask, then add 7g of liquid lipase CALB to the ternary mixed oil, and perform an ester exchange reaction under vacuum. The ester exchange reaction conditions are: reaction temperature 55℃, reaction time 4h. After the ester exchange reaction is completed, separate the liquid lipase CALB, and then wash the remaining crude shortening base oil with ethanol and desolventize it by vacuum rotary evaporation (temperature 50-60℃) to obtain the shortening base oil of this comparative example.

[0067] Comparative Example 3

[0068] The comparative example provides a shortening base oil, and the preparation method thereof comprises the following steps:

[0069] Take 65g of palm stearin in a round-bottom flask, melt it at 80℃, add 15g of cyperus oleifera oil and 20g of medium-chain triglyceride oil to obtain a ternary mixed oil. Evacuate the round-bottom flask, then add 7g of Pichia pastoris liquid lipase to the ternary mixed oil, and perform an ester exchange reaction under vacuum. The ester exchange reaction conditions are: reaction temperature 55℃, reaction time 4h. After the ester exchange reaction is completed, separate the Pichia pastoris liquid lipase, and then wash the remaining crude shortening base oil with ethanol and desolventize it by vacuum rotary evaporation (temperature 50-60℃) to obtain the shortening base oil of this comparative example.

[0070] Comparative Example 4

[0071] The comparative example provides a shortening base oil, and the preparation method thereof comprises the following steps:

[0072] 65g of palm stearin was put into a round-bottom flask, melted at 80°C, and then 15g of cyperus oleifera oil and 20g of medium-chain triglyceride oil were added to obtain a ternary mixed oil. The round-bottom flask was evacuated, and then 9g of immobilized lipase Novozym435 was added to the ternary mixed oil, and an ester exchange reaction was carried out under vacuum. The ester exchange reaction conditions were: reaction temperature 65°C, reaction time 3h. After the ester exchange reaction was completed, the immobilized lipase Novozym 435 was separated, and then the remaining crude shortening base oil was washed with ethanol and desolventized by vacuum rotary evaporation (temperature 50-60°C) to obtain the shortening base oil of the comparative example.

[0073] Comparative Example 5

[0074] The comparative example provides a shortening base oil, and the preparation method thereof comprises the following steps:

[0075] Take 45g of palm stearin in a round-bottom flask, melt it at 75℃, add 25g of cyperus oleifera oil and 30g of medium-chain triglyceride oil to obtain a ternary mixed oil. Evacuate the round-bottom flask, then add 9g of immobilized lipase Lipozyme RMIM to the ternary mixed oil, and carry out ester exchange reaction under vacuum. The ester exchange reaction conditions are: reaction temperature 65℃, reaction time 3h. After the ester exchange reaction, the immobilized lipase Lipozyme RMIM is separated, and then the obtained crude shortening base oil is washed with ethanol and desolventized by vacuum rotary evaporation (temperature 50-60℃) to obtain the shortening base oil of this comparative example.

[0076] Comparative Example 6

[0077] The comparative example provides a shortening base oil, and the preparation method thereof comprises the following steps:

[0078] 75g of palm stearin was put into a round-bottom flask, melted at 75°C, and then 10g of cyperus oleifera oil and 15g of medium-chain triglyceride oil were added to obtain a ternary mixed oil. The round-bottom flask was evacuated, and then 9g of immobilized lipase Lipozyme RMIM was added to the ternary mixed oil, and an ester exchange reaction was carried out under vacuum. The ester exchange reaction conditions were: reaction temperature 65°C, reaction time 3h. After the ester exchange reaction was completed, the immobilized lipase Lipozyme RMIM was separated, and then the obtained crude shortening base oil was washed with ethanol and desolventized by vacuum rotary evaporation (temperature 50-60°C) to obtain the shortening base oil of this comparative example.

[0079] 3. Test Examples

[0080] (1) Testing of melting point, composition and solid fat content of shortening

[0081] This test example tests various indicators of the shortening base oil prepared by Examples 1 to 4 and Comparative Examples 1 to 6. Among them, the melting point (SMP) is measured with reference to GB / T 24892 2010. The fatty acid composition is determined by gas chromatography, and the oleic acid content is obtained by area normalization. The content of medium and long carbon chain triglycerides is qualitatively determined by liquid chromatography-mass spectrometry. The trans fatty acid content is also detected by gas chromatography. The solid fat content (SFC) is measured with reference to AOCSOfficial Method Cd 16-b 93 and low-field nuclear magnetic resonance.

[0082] The melting point and composition test results of the shortening base oils of Examples 1 to 4 and Comparative Examples 1 to 6 are shown in Table 2. The SFC content results of the shortening base oils of Examples 1 to 4 and Comparative Examples 1 to 6 at different temperatures are shown in Table 3. Among them, in Table 2, the oleic acid content and proportion of Examples 2 to 4 and Comparative Examples 1 to 4 are the same. Since the proportion of the transesterified raw materials is not changed, the transesterification reaction does not change the fatty acid composition of the raw materials, and therefore the characterized fatty acid composition is the same.

[0083] Table 2 Melting point and composition test of shortening base oil of Examples 1 to 4 and Comparative Examples 1 to 6

[0084]

[0085]

[0086] Table 3 SFC content of shortening base oils of Examples 1 to 4 and Comparative Examples 1 to 6 at different temperatures (%)

[0087] Grouping 0℃ 5℃ 10℃ 15℃ 20℃ 25℃ 30℃ 35℃ 40℃ 45℃ 50℃ Example 1 42.81 37.06 34.39 27.61 21.9 14.33 8.48 4.79 2.72 0.32 0.07 Example 2 53.62 52.2 45.83 36.31 30.41 21.36 12.57 7.23 4.17 1.21 0.17 Example 3 56.65 55.29 47.75 37.34 30.57 20.21 11.01 6.12 3.29 0.59 0 Example 4 53.73 52.83 46.67 36.64 30.96 22.1 13.09 7.77 4.53 1.63 0.21 Comparative Example 1 48.12 46.49 40.37 29.92 21.55 14.22 9.11 5.21 2.84 0.37 0.15 Comparative Example 2 69.66 68.57 64.37 58.72 50.52 41.35 33.13 25.84 19.21 13.38 6.95 Comparative Example 3 63.17 63.18 59.35 53.25 45.39 36.68 29.27 22.71 16.91 11.99 5.44 Comparative Example 4 60.18 59.02 56.88 50.17 43.54 34.19 25.46 18.89 13.25 8.94 3.96 Comparative Example 5 37.31 35.49 28.06 21.59 15.06 7.58 3.71 1.69 0.56 0 0 Comparative Example 6 65.65 64.93 58.09 46.56 39.23 28.57 16.86 9.62 5.49 2.11 0.36

[0088] It can be seen from Table 2 combined with Table 3 that in the fatty acid composition of the shortening base oil prepared in Examples 1 to 4 of the present invention, oleic acid accounts for about 90% of the unsaturated fatty acid content, and oleic acid has both high nutritional value and high stability, and is called "safe fatty acid". In addition, the base oil is also rich in medium- and long-chain triglycerides, with a content of more than 50%. In the present invention, the medium-chain fatty acids undergo ester exchange with long-chain triglycerides to generate medium- and long-chain triglycerides while reducing the content of long-chain saturated fatty acids in the shortening base oil. Caprylic acid and capric acid in the medium-chain triglyceride oil are both saturated fatty acids, but their chain lengths are shorter, and they have different metabolic pathways in the human body from long-chain saturated fatty acids. Medium-chain fatty acids can pass through the portal vein like glucose, and are rapidly oxidized and release energy in liver cells, directly provide energy through β-oxidation, and are not easily accumulated as fat. In other words, medium- and long-chain triglycerides can provide energy to the human body quickly and steadily, and are not easy to cause fat accumulation, which can reduce the obesity rate and the incidence of a series of diseases caused by fat accumulation. Therefore, the shortening base oil prepared by the present invention is a new type of nutritious and healthy oil, which better meets the consumer's demand for low-calorie and high-nutrition healthy food.

[0089] At the same time, the sliding melting point of the base oil of the present invention is between 35 and 40°C, which meets the melting point standard of shortening. Furthermore, the SFC of the shortening base oil prepared by the present invention is 20℃ The SFC is 20% to 32%, which can provide good plasticity at room temperature and facilitate product shaping. 35℃ The shortening base oil prepared by the present invention after esterification has good processing and edible properties.

[0090] In addition, the present invention directly uses the immobilized enzyme Lipozyme RMIM to catalyze the transesterification reaction. The immobilized enzyme can be separated from the product by filtering after the reaction is completed, which is convenient and quick, and can be recycled and reused multiple times, which is conducive to reducing production costs. In addition, the crude product prepared by the immobilized enzyme catalyzed transesterification has a low acid value (FFA content of 2-3% after testing), is easy to separate and purify, and can save production costs.

[0091] Among them, the shortening base oil of Comparative Example 1 is prepared by using a chemical catalyst sodium methoxide, and the reaction temperature is high, which is easy to destroy the active ingredients in the oil. According to the test, the active ingredients in the oil are seriously lost during the reaction (VE loss is 50%, sterol loss is 8%), resulting in the shortening base oil having a darker color; and the product needs to be decolorized, the post-processing process is complicated, and the reaction is not environmentally friendly.

[0092] The shortening base oil prepared in Comparative Example 2 has an SFC of 25.84% at 35° C., which is much higher than the maximum requirement (10%) of SFC at 35° C., and the SFC curve does not meet the requirements of shortening; and it contains almost no medium- and long-chain triglycerides; in addition, it is difficult to separate the liquid enzyme from the product, and the water contained in the liquid enzyme will cause the triglyceride to hydrolyze, making the acid value of the reaction product too high (AV is 8-10 mg / g after testing), making separation and purification difficult.

[0093] The shortening base oil prepared in Comparative Example 3 has an SFC of 22.71% at 35° C., which is also higher than the maximum requirement (10%) of SFC at 35° C., and the SFC curve does not meet the requirements of shortening; at the same time, the content of medium and long carbon chain triglycerides is low; it is difficult to separate the liquid enzyme from the product, and the water contained in the liquid enzyme will cause the triglyceride to hydrolyze, making the acid value of the reaction product too high (AV>15 mg / g after testing), making separation and purification difficult.

[0094] The shortening base oil prepared in Comparative Example 4 has a high melting point, and the SFC at 35°C is 18.89%, which is 10% higher than the maximum requirement of SFC at 35°C. The SFC curve does not meet the shortening requirements, and the waxy feeling is heavy when it enters the mouth. At the same time, the content of medium and long carbon chain triglycerides is low, only 11.28%.

[0095] The shortening base oil prepared in Comparative Example 5 has a high content of medium and long carbon chain triglycerides, but the melting point (28.85° C.) of the shortening base oil is too low, the SFC at 20° C. is only 15.06%, and the operating properties at room temperature, such as plasticity, are poor, so it is not suitable for use as a shortening base oil.

[0096] The shortening base oil prepared in Comparative Example 6 has a melting point and SFC curve that basically meet the requirements of shortening base oil, but the content of medium and long carbon chain triglycerides is relatively low, only 42.59%. However, from the perspective of low calories and nutritional health, the shortening of Comparative Example 6 is inferior to the shortening of the present invention.

[0097] (2) SFC comparison test of shortening base oil of the present invention and physical mixed oil

[0098] The raw material oil used in the embodiment of the present invention was physically mixed with palm stearin, cyperus oleifera oil and medium-chain triglyceride oil in a mass ratio of 65:15:20 to prepare a physical mixed oil (denoted as PB). Then, the solid fat content (SFC) of the physical mixed oil was measured at different temperature ranges and compared with the shortening base oil (denoted as EIE) prepared in Example 3 of the present invention. The SFC test results of the two are as follows: Figure 1 shown.

[0099] Depend on Figure 1It can be seen that compared with the physical mixed oil (PB), the shortening product (EIE) of the present invention changes the SFC curve of the shortening base oil and reduces its SFC at high temperature, especially SFC 35℃ It is significantly reduced, which helps to reduce the waxy feeling when the oil enters the mouth.

[0100] (3) XRD analysis and thermal property analysis

[0101] The shortening base oil (EIE) prepared in Example 3 of the present invention, the physical mixed oil (PB) prepared above, the raw material palm stearin (PSt) and a shortening of a certain brand (No. CS1) purchased from a commercial channel were analyzed by X-ray diffraction technology and DSC thermal analysis technology. The XRD crystal form analysis results are as follows: Figure 2 The thermal properties analysis results are shown in Figure 3 shown.

[0102] Depend on Figure 2 It can be seen that the unstable α crystal form in the oil crystallization is completely eliminated by the ester exchange, and the content of stable β and β' crystal forms in the base oil is increased, which has a significant advantage in crystallization stability compared with traditional commercial shortening.

[0103] Depend on Figure 3 It can be seen that by characterizing the thermal properties through DSC, it is found that the number of endothermic peaks of the shortening base oil of the present invention is increased compared with the traditional commercial shortening, the peak area of ​​each peak is decreased, and the oil shows a slow melting process, which is more suitable for baked foods.

[0104] (4) Comparison of properties between shortening of the present invention and commercially available shortening

[0105] The present invention collected eight shortening samples of different brands from commercial channels, numbered CS1 to CS8, and compared their properties (including melting point, long-chain saturated fatty acid content, medium-chain fatty acid content, oleic acid content and SFC content). 35℃ ) were analyzed and compared with the shortening base oil prepared in Example 3 of the present invention. The results are shown in Table 4. "ND" means not detected.

[0106] Table 4. Comparison of properties of shortening of the present invention and commercially available shortening

[0107]

[0108]

[0109] As shown in Table 4, the shortening base oil prepared by the present invention has a SFC 35℃The SFC of the shortening of the present invention is 6.12%, which is significantly lower than the average value (21.41%) of 8 commercial shortenings. The lower SFC indicates that the shortening of the present invention can reduce the waxy feeling of fat when entering the mouth at a temperature close to the human body, which is beneficial to improving the edible performance. In addition, the content of long-chain saturated fatty acids in the shortening of the present invention is reduced by about 10% compared with the average value of 8 commercial shortenings, and the content of medium-chain fatty acids is increased by more than 12% compared with commercial shortenings, which is more conducive to reducing calories and improving the nutritional value of food.

[0110] (5) Oxidative stability test of shortening base oil

[0111] Since most commercial shortenings (CS1-CS8) are added with exogenous antioxidants, it is impossible to test the oxidative stability of the original shortening before adding the antioxidants. Therefore, the present invention specifically selects high linoleic acid type oil sunflower oil (SFO) and high linolenic acid type oil linseed oil (LSO) with representative fatty acid composition as liquid oil raw materials, and uses palm stearin (PSt) used in the embodiment of the present invention as solid fat raw material through transesterification reaction to prepare shortening base oil with SFC curve similar to that of the shortening base oil in Example 3 of the present invention, and conducts a comparative experiment on the oxidative stability of shortening.

[0112] Among them, the preparation method of shortening base oil prepared by transesterification of SFO and PSt is: take 70g of PSt in a round-bottom flask, melt it at 75°C, add 30g of SFO, and obtain a binary mixed oil. The other reaction and purification conditions are exactly the same as those in Example 3. The preparation method of shortening base oil prepared by transesterification of LSO and PSt is: take 65g of PSt in a round-bottom flask, melt it at 75°C, add 35g of LSO, and obtain a binary mixed oil. The other reaction and purification conditions are exactly the same as those in Example 3. It should be noted that the transesterified raw oils (palm stearin, jatropha oil and medium-chain triglyceride oil) in the examples of the present invention and the sunflower oil and linseed oil raw materials in the comparative oils do not contain exogenous antioxidants.

[0113] The SFC curves of the shortening base oil prepared from sunflower seed oil and palm stearin (denoted as PSt:SFO), the shortening base oil prepared from linseed oil and palm stearin (denoted as PSt:LSO), and the shortening base oil of Example 3 of the present invention (denoted as PSt:TNO:MCTO) are compared as shown in the figure below. Figure 4 As shown. Figure 4 It can be seen that the shortening base oil prepared from sunflower seed oil and palm stearin, the shortening base oil prepared from linseed oil and palm stearin, and the shortening base oil of Example 3 of the present invention have similar SFC curves.

[0114] Further, under the condition that the SFC curves of the above three oils are similar and no exogenous antioxidant is added, the oxidation induction period of the above PSt:SFO, PSt:LSO, and PSt:TNO:MCTO is measured at 120°C using an oxidation induction instrument to characterize its oxidation stability. The longer the oxidation induction period, the better its oxidation stability. The test results of the oxidation induction period of PSt:SFO, PSt:LSO, and PSt:TNO:MCTO are shown in Table 5.

[0115] Table 5. Comparison of oxidation stability

[0116] Shortening base oil name Oxidation induction period (h) Shortening made from sunflower oil and palm stearin PSt:SFO 2.84 Shortening made from linseed oil and palm stearin PSt:LSO 2.32 Shortening prepared in Example 3 of the present invention PSt:TNO:MCTO 14.44

[0117] As shown in Table 5, without adding an antioxidant, the oxidation induction period of the shortening base oil of the present invention is as long as 14.44 h, which is 5.1 times that of the shortening base oil prepared from sunflower oil and 6.2 times that of the shortening base oil prepared from linseed oil. This proves that the shortening base oil prepared by the present invention has low calories and high nutrition, and also has outstanding oxidation stability, which is more conducive to improving the quality of baked foods.

[0118] In summary, the present invention uses palm stearin, jatropha oil and medium-chain triglyceride oil as raw materials and uses immobilized lipase Lipozyme RMIM as a catalyst to prepare a shortening base oil that is zero-trans, low in cholesterol, low in calories, has good processing and edible properties and excellent oxidative stability, and comprehensively solves the problems of poor oxidative stability of shortening, high cholesterol content, excessive trans fatty acids and high content of long-chain saturated fatty acids, and has extremely broad application prospects in the field of preparation of low-calorie, high-nutrition and high-quality shortening.

[0119] Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent substitutions for some of the technical features therein; and these modifications or substitutions do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a shortening base oil with low calorie content and high oxidation stability, characterized in that: The following steps are involved: The palm stearin, cyperus oleifera oil and medium-chain triglyceride oil are uniformly mixed to obtain a mixed oil; immobilized lipase Lipozyme RMIM is added to the mixed oil to carry out an ester exchange reaction, and then purified to obtain a shortening base oil with low heat and high oxidation stability; Among them, in the mixed oil, the mass ratio of palm stearin, cyperus oleifera oil and medium-chain triglyceride oil is (55-65): (15-20): (20-25); in the fatty acid composition of the palm stearin, the content of long-chain saturated fatty acids is ≥58%; in the fatty acid composition of the cyperus oleifera oil, the content of oleic acid is ≥65%; in the fatty acid composition of the medium-chain triglyceride oil, the content of medium-chain fatty acids is ≥95%.

2. The method for preparing a shortening base oil with low calorie content and high oxidation stability according to claim 1, characterized in that: In the fatty acid composition of the palm stearin, the content of palmitic acid is 54% to 60%, the content of oleic acid is 28% to 33%, the content of linoleic acid is 5% to 8%, and the content of stearic acid is 4% to 7%.

3. The method for preparing a shortening base oil with low calorie content and high oxidation stability according to claim 1, characterized in that: In the fatty acid composition of the jatropha oil, the content of oleic acid is 65% to 80%, the content of palmitic acid is 10% to 15%, and the content of linoleic acid is 6% to 14%.

4. The method for preparing a shortening base oil with low calorie content and high oxidation stability according to claim 1, characterized in that: In the fatty acid composition of the medium-chain triglyceride oil, the content of caprylic acid is 52% to 55%, and the content of capric acid is 43% to 48%.

5. The method for preparing a shortening base oil with low calorie content and high oxidation stability according to any one of claims 1 to 4, characterized in that: The added mass of the immobilized lipase Lipozyme RMIM is 5% to 9% of the mixed oil.

6. The method for preparing a shortening base oil with low calorie content and high oxidation stability according to any one of claims 1 to 4, characterized in that: The temperature of the transesterification reaction is 60-70° C., and the time of the transesterification reaction is 2-4 hours.

7. The method for preparing a shortening base oil with low calorie content and high oxidation stability according to any one of claims 1 to 4, characterized in that: The transesterification reaction is carried out under vacuum conditions.

8. The method for preparing a shortening base oil with low calorie content and high oxidation stability according to any one of claims 1 to 4, characterized in that: The purification process is as follows: after the transesterification reaction is completed, the immobilized lipase Lipozyme RMIM is firstly separated, and then alcohol washing and vacuum desolventizing are performed in sequence.

9. The method for preparing a shortening base oil with low calorie content and high oxidation stability according to claim 8, characterized in that: The solvent used in the alcohol washing is ethanol; the temperature of the vacuum desolventizing treatment is 50-60°C.

10. A shortening base oil with low calorie content and high oxidation stability prepared by the preparation method according to any one of claims 1 to 9.

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