Low-cholesterol lard oil and preparation method thereof

Abstract

The invention belongs to the technical field of food processing, and discloses low-cholesterol lard oil and a preparation method thereof. The low-cholesterol lard uses natural lotus leaves as a cholesterol removal agent, and the cholesterol content is 13-15 mg / 100g. In the preparation process, nuciferine and other components of the natural lotus leaves fully act with cholesterol in the lard oil through two times of variable-temperature steaming and stage low-temperature crystallization treatment, so that separation and removal are facilitated, and the content of cholesterol in the lard oil is further remarkably reduced.

Description

Technical Field

[0001] The invention relates to the technical field of food processing, in particular to low-cholesterol lard and a preparation method thereof. Background Art

[0002] Lard is a traditional edible oil with dual value in culinary applications and nutritional benefits. It not only has high thermal stability and a unique flavor profile, but also provides ample energy and fat-soluble nutrients, including vitamin D, vitamin A, and essential fatty acids. However, as an animal fat, lard is also rich in saturated fatty acids and cholesterol, with the cholesterol content in conventional lard typically ranging from 90-95 mg / 100 g. Cholesterol is an essential physiologically active substance in cellular tissues, participating in the formation of cell membranes and serving as a raw material for the synthesis of bile acids, vitamin D, and steroid hormones. Cholesterol is divided into high-density lipoprotein (HDL) cholesterol (HDL-C) and low-density lipoprotein (LDL-C). The HDL-C, often referred to as "good cholesterol," has protective effects on cardiovascular health, while the LDL-C, often referred to as "bad cholesterol," increases the risk of coronary heart disease. Studies have shown that moderate lard intake can maintain HDL levels and promote cardiovascular health through reverse cholesterol transport. However, excessive intake can lead to abnormal cholesterol deposition in peripheral blood vessels, increasing the risk of atherosclerosis and metabolic syndrome. This conflict has fueled market demand for low-cholesterol lard products and driven the development of related cholesterol removal technologies.

[0003] In addition to taking measures in pig breeding and feed, a more effective way to reduce the cholesterol content in lard is to remove the cholesterol from lard. Current cholesterol removal technologies can be divided into three categories: physical separation methods, including low-temperature crystallization, molecular distillation, and supercritical CO2 extraction, which utilize the phase change properties of cholesterol to achieve selective separation; chemical adsorption methods, which use plant sterols, dietary fiber, and cyclodextrins for adsorption removal; and biotransformation methods, which use cholesterol oxidase to convert cholesterol into inactive cholester-4-en-3-one. However, these methods generally face engineering bottlenecks, high costs for equipment, extraction reagents, and the extraction process, as well as damage to natural flavor, chemical loading, and poor cleanliness and environmental protection.

[0004] In view of this, the present invention is proposed. Summary of the Invention

[0005] The present invention aims to provide a low-cholesterol lard, which uses natural lotus leaves as a cholesterol-removing agent and has a low cholesterol content. The present invention also provides a method for preparing the low-cholesterol lard.

[0006] In order to achieve the above objectives, the first technical solution adopted by the present invention is: The low-cholesterol lard uses natural lotus leaves as a cholesterol-removing agent, and the cholesterol content of the lard is 13-15 mg / 100 g.

[0007] The second technical solution adopted in the present invention is: The preparation method of low-cholesterol lard comprises the following steps: Fresh lard is minced and spread between two layers of fresh lotus leaves, and steamed at a first temperature change to obtain initial lard; Lotus leaf juice is added to the initial lard, and after the second temperature-variable steaming, a stage low-temperature crystallization separation treatment is performed.

[0008] Furthermore, the first temperature-variable steaming comprises: first steaming at 60-65° C. for 40-50 min, then heating to 110-120° C., and steaming until the lard is completely melted.

[0009] Furthermore, the second temperature-variable steaming includes: first steaming at 65-70° C. for 45-50 min, then heating to 115-120° C., and steaming until the lotus leaf juice is completely evaporated.

[0010] Furthermore, the mass ratio of the initial lard to the lotus leaf juice is 80-85:15-20.

[0011] Furthermore, the lotus leaf juice is obtained by chopping fresh lotus leaves at high speed at low temperature and filtering.

[0012] Furthermore, the low-temperature crystallization separation treatment in the stage includes: cooling the initial lard to 35-40°C at a rate of 1-2°C / min, keeping it warm and standing for 3-4 hours, then centrifuging to remove the precipitate, then heating it to 65-70°C and keeping it warm and stirring for 45-50 minutes, heating it to 115-120°C and then cooling it to 35-40°C at a rate of 1-2°C / min, keeping it warm and standing for 3-3.5 hours, and then collecting the liquid lard.

[0013] Furthermore, the centrifugal speed is 8000-10000 rpm and the time is 12-15 min.

[0014] Furthermore, the low-temperature crystallization and separation treatment in the above stage also includes refining, decolorization and drying.

[0015] Furthermore, the drying method is vacuum drying.

[0016] Compared with the prior art, the present invention has the following beneficial effects: 1. The low-cholesterol lard provided by the present invention uses natural lotus leaves as a cholesterol-removing agent. On the basis of conventional lard, the cholesterol is removed by more than 80%, and the cholesterol content is reduced to 13-15 mg / 100 g.

[0017] 2. The preparation method provided by the present invention, through two temperature-variable steaming and staged low-temperature crystallization treatment, allows the nuciferine and other components of natural lotus leaves to fully react with the cholesterol in lard, facilitating separation and removal, thereby significantly reducing the cholesterol content in lard.

[0018] 3. The preparation method of the present invention has the advantages of being natural, low-cost, and free of chemical residues, and can better meet the requirements of modern food clean labeling and clean production. DETAILED DESCRIPTION

[0019] To make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are described clearly and completely below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer are used. Where the manufacturer of the reagents or instruments is not specified, all are conventional products that can be purchased commercially.

[0020] A first embodiment of the present invention provides low-cholesterol lard, using natural lotus leaves as a cholesterol-removing agent, and the cholesterol content in the lard is 13-15 mg / 100 g.

[0021] Nuciferine present in lotus leaves can form an insoluble complex with cholesterol through emulsification, encapsulation, and other effects. This cholesterol-insoluble complex and cholesterol will crystallize and precipitate at low temperatures, and cholesterol can be removed by separating the crystals. Existing studies usually use simple nuciferine in conjunction with physical separation to remove cholesterol from materials. Not only is the extraction of nuciferine tedious and complicated, but the cholesterol removal effect is also unsatisfactory. The applicant of the present invention has found in their research that using natural lotus leaves as a cholesterol-removing agent in lard, the other components contained in natural lotus leaves can produce a synergistic effect with nuciferine, further reducing the solubility of cholesterol, which is more conducive to the removal of cholesterol in lard.

[0022] The low-cholesterol lard provided by the present invention has over 80% of the cholesterol removed from conventional lard, significantly reducing the cholesterol content. The low-cholesterol lard is filled using conventional methods, such as aseptically filling into food-grade containers such as tinplate cans, PET bottles, and glass bottles, and then stored in a nitrogen-filled or vacuum-packed environment away from light. The product has a shelf life of 9-12 months.

[0023] A second embodiment of the present invention provides a method for preparing low-cholesterol lard, comprising the following steps: Fresh lard is minced and spread between two layers of fresh lotus leaves, and steamed at a first temperature change to obtain initial lard; Lotus leaf juice is added to the initial lard, and after the second temperature-variable steaming, a stage low-temperature crystallization separation treatment is performed.

[0024] The embodiment of the present invention is to give full play to the effect of nuciferine and other components in natural lotus leaves on reducing the solubility of cholesterol in lard. Different from the existing lard refining technology of dry boiling and dry frying, the present invention refines lard by steaming. Specifically, the present invention alternately lays minced pork fat and lotus leaves so that the pork fat is between two layers of lotus leaves. The first temperature-variable steaming is carried out until the pork fat is completely melted into the initial oil, and then lotus leaf juice is added for the second temperature-variable steaming treatment. The above two different forms of natural lotus leaf treatment can maximize the formation of insoluble complexes of cholesterol in lard, significantly reducing the solubility of cholesterol in lard, facilitating the subsequent formation of crystals for separation and removal. It is understandable that in actual production, depending on the size of the steaming equipment, multiple layers of lard and lotus leaves can be laid alternately to achieve large-scale production, but the lotus leaf-pork fat-lotus leaf sandwich form must be strictly followed. In addition, compared with refining technologies such as dry boiling and dry frying, the steaming and refining method of the present invention can also increase the oil yield by more than 10%.

[0025] Furthermore, the embodiment of the present invention fully separates and removes cholesterol from lard through staged low-temperature crystallization separation treatment. Specifically, the lard that has undergone the second temperature-variable steaming treatment is first cooled to 35-40°C at a rate of 1-2°C / min and allowed to stand at this temperature for 3-4 hours. During this process, the phospholipids, proteins and other hydrophilic impurities in the lard act as crystal nuclei and preferentially form insoluble low-melting-point eutectic complexes with cholesterol through intermolecular forces. Such eutectic precipitates are removed by centrifugation. The lard is then heated to 65-70°C and kept warm with stirring for 45-50 minutes. After heating to 115-120°C, the temperature is cooled to 35-40°C at a rate of 1-2°C / min and allowed to stand at this temperature for 3-3.5 hours. At this time, the impurities in the lard are greatly reduced, and the remaining cholesterol mainly aggregates with high-melting-point saturated glycerides through van der Waals forces and hydrophobic interactions to form crystal nuclei, and then gradually forms solid oil crystals with a high melting point and high cholesterol content. Such crystal precipitates are intercepted using a mesh-containing oil leakage container, and the melted liquid lard is collected to obtain low-cholesterol lard. The embodiment of the present invention selects fresh pig fat, rinses it with clean water to remove blood, minced meat and other impurities, puts it into a cold storage and cools it to a temperature of 0-2 ° C, and then minces it to 2-3 cm 3 .

[0026] In one embodiment, the first variable temperature steaming step involves steaming at 60-65°C for 40-50 minutes, then increasing the temperature to 110-120°C until the lard is completely melted. The second variable temperature steaming step involves steaming at 65-70°C for 45-50 minutes, then increasing the temperature to 115-120°C until the lotus leaf juice is completely evaporated (approximately 1.5-2 hours). It should be noted that both variable temperature steaming steps require the initial steaming at a lower temperature to ensure that the nuciferine and other components in the natural lotus leaves fully react with the cholesterol in the lard.

[0027] In one embodiment, lotus leaf juice is obtained by chopping fresh lotus leaves at low temperature and filtering them at high speed. Specifically, the fresh lotus leaves are rinsed with clean water to remove attached dirt and impurities, then chopped at 900-1100 rpm. Ice chips (10%-15% by weight of the fresh lotus leaves) are then added to create a low-temperature environment. The leaves are then chopped at 2300-2400 rpm into a fine pulp, which is then filtered to remove the residue. If a chopper with a cooling function is used, clean water (10%-15% by weight of the lotus leaves) is added and the instrument temperature is controlled at 6-8°C.

[0028] In the stage low-temperature crystallization separation treatment, the centrifugal speed is 8000-10000 rpm, and the time is 15 minutes. After the stage low-temperature crystallization separation treatment, refining, decolorization and drying treatment are also included. These treatments are conventional processing steps in lard processing. Those skilled in the art can select and adjust them according to actual conditions. The embodiments of the present invention are not particularly limited. For example, food-grade activated carbon is used for refining and decolorization. Specifically, 1.5%-2.0% of the weight of food-grade activated carbon is added to the lard, and after stirring at 80-90 ° C for 30 minutes, the adsorbent and fine particles are removed by a plate filter or a press. After refining and decolorization, vacuum drying is performed to remove the remaining moisture to obtain the low-cholesterol lard product.

[0029] In order to make the present invention clearer, examples for implementing the present invention and corresponding comparative examples will be disclosed below to demonstrate the relevant technical effects of the present invention.

[0030] The lard used in the following examples was derived from lard produced by an enterprise of the applicant of the present invention, and fresh lotus leaves were collected in Suining City.

[0031] The cholesterol content detection method involved in the embodiment is: GB 5009.128-2016 "National Food Safety Standard Determination of Cholesterol in Foods" Method 1 Gas Chromatography.

[0032] Example 1 Experimental group: Preparation of low-cholesterol lard Fresh lard was minced and placed alternately with fresh lotus leaves so that it was placed between two layers of lotus leaves. The lard was steamed at 65°C for 40 min, then heated to 115°C and steamed until the lard was completely melted to obtain the initial lard. Chop fresh lotus leaves into fine pieces, add ice chips (15% of the weight of the lotus leaves), chop at 2300 rpm to form a fine pulp, and filter to obtain lotus leaf juice; The initial lard and lotus leaf juice were mixed in a mass ratio of 80:20, stirred and steamed at 65°C for 40 min, heated to 120°C, and continued to be stirred and steamed for about 1.6 h until the lotus leaf juice was completely evaporated. The mixture was then cooled to 35°C at a rate of 2°C / min and allowed to stand at this temperature for 3.5 h to allow cholesterol and residual impurities to co-crystallize. The mixture was centrifuged at 9000 rpm for 15 min to remove the precipitate, and then heated to 65°C and stirred for 45 min. After heating to 115°C, the mixture was cooled to 40°C at a rate of 2°C / min and allowed to stand for 3.5 hours to allow the oil crystals with high melting point and high cholesterol content to sink to the bottom. The melted liquid lard was collected using an oil leak net, refined, decolorized, and dried to obtain low-cholesterol lard.

[0033] The following control groups were set up based on the above experimental groups: Control group 1: Conventional lard was prepared according to the traditional boiling process, specifically: minced lard was boiled at 120°C until melted and precipitated, and the oil residue was filtered out to obtain conventional lard.

[0034] Control group 2: In the preparation of the initial lard, the steaming method was replaced by the boiling method, specifically: the minced lard was boiled at 120°C until it melted and precipitated, and the oil residue was filtered out to obtain the initial lard.

[0035] Control group 3: In the initial lard preparation, fresh lotus leaves were replaced with an equal amount of 10% nuciferine solution (the nuciferine content was much higher than that of fresh lotus leaves), which was sprayed on the lard and then steamed.

[0036] Control group 4: During the initial lard preparation, the lard was directly steamed at 115°C until the lard was completely melted.

[0037] Control group 5: After the initial lard was mixed with lotus leaf juice, it was directly steamed at 120°C until the lotus leaf juice was completely evaporated.

[0038] Control group 6: After the initial lard was mixed with lotus leaf juice, it was boiled at 120°C until the lotus leaf juice was completely evaporated.

[0039] Control group 7: The step of adding lotus leaf juice for steaming was omitted, and the initial lard was directly subjected to crystallization and separation treatment.

[0040] Control group 8: During the preparation of liquid lard, the temperature was naturally lowered to 35°C and 40°C.

[0041] Control group 9: only one low-temperature crystallization separation treatment was performed, that is, in the liquid lard preparation step, liquid lard was obtained by centrifugation and removal of precipitation.

[0042] The cholesterol content of the lard in the experimental group and the control group was determined, and the cholesterol removal rate of the low-cholesterol lard in the remaining groups was calculated based on the conventional lard in the control group 1. The calculation formula is as follows: .

[0043] The results of the determination of cholesterol content in lard of each group and the calculation results of cholesterol removal rate are shown in Table 1.

[0044] Table 1 Cholesterol content determination and cholesterol removal rate calculation results of lard in different groups .

[0045] According to the results in Table 1, it can be seen that the cholesterol content of the low-cholesterol lard prepared by the patented method is significantly reduced compared with the conventional lard prepared by the traditional process in the control group 1, and the removal rate reaches 84%; the changes in the cooking method and crystallization separation method of the lard in the control groups 2-9 will reduce the cholesterol removal effect in the lard.

[0046] Example 2 Preparing low-cholesterol lard Fresh lard was minced and placed alternately with fresh lotus leaves so that it was placed between two layers of lotus leaves. The mixture was steamed at 60°C for 50 min, then heated to 110°C and steamed until the lard was completely melted to obtain the initial lard. Chop fresh lotus leaves into fine pulp, add 13% water of the lotus leaf weight, chop at 7℃ and 2300 rpm to obtain a fine pulp, and filter to obtain lotus leaf juice; The initial lard and lotus leaf juice were mixed in a mass ratio of 85:15, stirred and steamed at 70 ℃ for 45 min, heated to 115 ℃, and continued to stir and steam for about 1.8 h until the lotus leaf juice was completely evaporated. The mixture was then cooled to 40 ℃ at a rate of 2 ℃ / min and allowed to stand at this temperature for 3.5 h to allow cholesterol and residual impurities to co-crystallize. The mixture was centrifuged at 9400 rpm for 15 min to remove the precipitate, and then heated to 70 ℃ and stirred for 50 min. After heating to 120 ℃, the mixture was cooled to 40 ℃ at a rate of 1.5 ℃ / min and allowed to stand for 3 hours to allow the oil crystals with high melting point and high cholesterol content to sink to the bottom. The melted liquid lard was collected using an oil leak net, refined, decolorized, and dried to obtain low-cholesterol lard.

[0047] After testing, the cholesterol content in the prepared low-cholesterol lard was 13 mg / 100 g.

[0048] The embodiments described above are some embodiments of the present invention, rather than all embodiments. The detailed description of the embodiments of the present invention is not intended to limit the scope of the invention as claimed, but rather merely represents selected embodiments of the present invention. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort are also within the scope of protection of the present invention.

Claims

1. Low cholesterol lard, characterized in that Natural lotus leaves are used as a cholesterol-removing agent, and the cholesterol content in the lard is 13-15 mg / 100 g.

2. A method for preparing low-cholesterol lard, characterized in that: The following steps are involved: Fresh lard is minced and spread between two layers of fresh lotus leaves, and steamed at a first temperature change to obtain initial lard; Lotus leaf juice is added to the initial lard, and after the second temperature-variable steaming, a stage low-temperature crystallization separation treatment is performed.

3. The preparation method according to claim 2, wherein The first temperature-variable steaming comprises: first steaming at 60-65° C. for 40-50 minutes, then heating to 110-120° C., and steaming until the lard is completely melted.

4. The preparation method according to claim 2, wherein The second temperature-variable steaming comprises: first steaming at 65-70° C. for 45-50 min, then heating to 115-120° C., and steaming until the lotus leaf juice is completely evaporated.

5. The preparation method according to claim 2, wherein The mass ratio of the initial lard to the lotus leaf juice is 80-85:15-20.

6. The preparation method according to claim 5, wherein The lotus leaf juice is obtained by chopping fresh lotus leaves at high speed under low temperature and filtering.

7. The preparation method according to claim 2, wherein The low-temperature crystallization separation treatment in the stage includes: first cooling to 35-40°C at a rate of 1-2°C / min, keeping it warm and standing for 3-4 hours, then centrifuging to remove the precipitate, then heating to 65-70°C and keeping it warm and stirring for 45-50 minutes, heating to 115-120°C and then cooling to 35-40°C at a rate of 1-2°C / min, keeping it warm and standing for 3-3.5 hours, and collecting liquid lard.

8. The preparation method according to claim 7, wherein The centrifugal speed is 8000-10000 rpm and the time is 12-15 min.

9. The preparation method according to claim 2, wherein The low-temperature crystallization and separation treatment in the above stage also includes refining, decolorization and drying.

10. The preparation method according to claim 9, characterized in that The drying method is vacuum drying.