Methods of extracting olive oil

Abstract

The present invention belongs to the technical field of olive oil processing, and specifically relates to a method for extracting olive oil. In order to increase the oil yield of olive oil and reduce the problem of loss of nutrients in olive oil, the present invention provides a method for extracting olive oil assisted by a high-voltage pulse electric field, comprising the following steps: washing and crushing olive fruits, sequentially performing high-voltage pulse treatment, stirring and fusing, solid-liquid separation, oil-water separation, and standing. The present invention uses a high-voltage pulse electric field to increase the oil yield of olives, reduce the acid value and peroxide value of olive oil, and increase the unsaturated fatty acid content, thereby improving the quality of olive oil, which is of great significance to the production of olive oil.

Description

Technical Field

[0001] The invention belongs to the technical field of olive oil processing, and in particular relates to a method for extracting olive oil with the assistance of a high-voltage pulse electric field. Background Art

[0002] Olive is a famous woody oil tree species in the world, and its cultivated varieties have high edible value. Olive oil is directly cold-pressed from fresh olive fruit, and is known as the "Queen of Vegetable Oils", "Liquid Gold", and "Mediterranean Nectar" because of its excellent natural health care and beauty effects and ideal cooking uses. Edible olive oil is the only pure natural woody edible vegetable oil in the world today that uses fresh fruit, is cold-pressed and ready to eat, and exists in a natural form. It has rich nutritional value and important economic value. Olive fruit is rich in unsaturated fatty acids, trace elements, vitamins, squalene, flavonoids, polyphenol compounds and other nutrients that are beneficial to the human body, but their content in olive oil is very small. Therefore, it is urgent to change the existing pressing process to improve the oil yield and quality of olive oil.

[0003] At present, the traditional olive oil pressing process uses fresh olive fruit washing, leaf removal, crushing, stirring and blending, solid-liquid separation, oil-water separation, and preliminary precipitation to obtain extra virgin olive oil. This process has simple equipment, convenient operation, and is also suitable for the characteristics of fresh olive fruit cold pressing. However, it leads to incomplete olive fruit wall breaking, resulting in a low olive oil yield. At the same time, a large amount of nutrients in the olive fruit water are lost with the wastewater, and there are very few nutrients in the olive oil, resulting in a waste problem. Summary of the invention

[0004] In order to increase the yield of olive oil and reduce the loss of nutrients in olive oil, the present invention provides a method for extracting olive oil assisted by a high-voltage pulse electric field. The olive oil obtained by this method has a higher yield, lower acid value and peroxide value, and increased unsaturated fatty acid content than the traditional process.

[0005] The present invention first provides a method for extracting olive oil assisted by a high-voltage pulse electric field, comprising the following steps:

[0006] After the olive fruits are washed and crushed, they are sequentially subjected to high-pressure pulse treatment, stirring and fusion, solid-liquid separation, oil-water separation, and allowed to stand.

[0007] Wherein, in the high-voltage pulse treatment, the pulse voltage is 6000-6500 V. Preferably, the pulse voltage is 6500 V.

[0008] Wherein, in the high-voltage pulse treatment, the pulse width is 30 μs.

[0009] Wherein, in the high voltage pulse treatment, the frequency is 10 to 75 Hz.

[0010] Wherein, in the high-voltage pulse treatment, the number of pulses is 15 to 30 times.

[0011] The stirring and fusion is carried out at a temperature of 28 to 38° C., a rotation speed of 60 r / min, and a time of 40 to 50 min.

[0012] Preferably, the stirring and blending time is 45 minutes.

[0013] Wherein, the solid-liquid separation adopts a horizontal centrifuge.

[0014] Wherein, the separation speed of the solid-liquid separation is 5000r / min, and the centrifugation time is 1min.

[0015] Wherein, the oil-water separation adopts a disc centrifuge.

[0016] Among them, the separation speed of the oil-water separation is 5900r / min, and the centrifugation time is 1min.

[0017] The static conditions are light-proof, oxygen-proof and a temperature of 15 to 18°C.

[0018] Wherein, the olive fruit is fresh olive fruit.

[0019] Beneficial effects: The present invention uses high-voltage pulse electric field technology to change the permeability of the olive fruit cell membrane, destroy the structure of the olive fruit cell membrane, so that the oil and unsaturated fatty acids inside the olive fruit are extracted to the maximum extent, and the quality of olive oil is improved. Compared with the existing traditional process of 14.2%, the method of the present invention increases the oil yield of olive oil to a maximum of 21.9%, reduces the acid value from 0.45 to 0.34, reduces the peroxide value from 1.24 to 0.72, and increases the relative content of unsaturated fatty acids from 82.5% to 83.5%, thereby greatly improving the oil yield of olive oil and improving the quality of olive oil. The method of the present invention also has the advantages of simple process, high efficiency, low processing temperature, and low energy consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 The process flow chart of the method of the present invention is shown in FIG. DETAILED DESCRIPTION

[0021] The object of the present invention is to provide a method for extracting olive oil assisted by a high-voltage pulse electric field, comprising the following steps:

[0022] 1) The olive fruits are washed and crushed, and then treated with a high-voltage pulse electric field to form jam, wherein the pulse voltage of the high-voltage pulse electric field is 6000-6500V, the pulse width is 30μs, the frequency is 10-75Hz, and the number of pulses is 15-30 times.

[0023] 2) stirring and blending the jam after the pulse treatment in 1) to obtain extracted fruit pulp; the stirring and blending temperature is 28-38° C., the rotation speed is 60 r / min, and the time is 40-50 min.

[0024] 3) The pulp extracted in 2) is subjected to solid-liquid separation using a horizontal centrifuge at a rotation speed of 5000 r / min and a centrifugal time of 1 min to obtain an oil-water mixture.

[0025] 4) The oil-water mixture obtained in 3) is separated into oil and water by a disc centrifuge at a separation speed of 5900 r / min and a centrifugal time of 1 min, and then allowed to stand to obtain olive oil.

[0026] In the present invention, the olive fruit is preferably fresh olive fruit.

[0027] The extraction of olive oil of the present invention is different from that of other vegetable oils, such as soybean and corn. Olive oil is generally a woody vegetable oil, which is usually extracted directly from olive fruits by physical low-temperature (28-38°C) cold pressing, and is a fruit juice oil. Ordinary vegetable oil is generally herbal vegetable oil, which is usually extracted by refining, physical hot pressing or chemical hot pressing. For example, the extraction of common soybean oil is by pure physical pressing and chemical extraction: (1) Pure physical pressing, soybean → washing → drying → crushing → screening → pressing → separation → soybean oil, whether to heat or cook before pressing, divided into cold pressing and hot pressing, and the hot pressing temperature is generally maintained at about 128°C; Solution extraction method (leaching method) is a soybean oil-making process commonly used in industry, soybean → washing → drying → crushing → embryo rolling → adjusting leaching conditions → leaching (60°C) → six degreasing (defatting, degumming, dehydration, decolorization, deodorization, deacidification) → soybean oil.

[0028] Corn oil extraction: (1) Pressing method, the process of preparing oil includes cleaning, drying, softening (60°C), rolling, steaming, oil extraction and refining; (2) Leaching method, immersing the pre-pressed cake in a selected solvent so that the oil can be dissolved in the solvent to form a mixed oil. After the mixed oil is prepared, the mixed oil and solid residue can be separated, and then the mixed oil is evaporated and stripped according to different boiling points, so that the solvent can be vaporized into steam to the maximum extent, and separated from the oil, and finally the oil is obtained. Therefore, since the nature of the raw materials for the extraction of olive oil of the present invention is different from the raw materials based on other vegetable oils, the extraction methods of other vegetable oils cannot be used as a reference for the extraction of olive oil of the present invention.

[0029] In the present invention, high-voltage pulse electric field technology is used to change the permeability of olive fruit cell membranes, destroy the structure of olive fruit cell membranes, and extract the oil and unsaturated fatty acids inside the olive fruit to the maximum extent, thereby reducing the acid value and peroxide value, and improving the oil yield and quality of olive oil. At the same time, the high-voltage pulse electric field can achieve a sterilization effect, thereby improving the safety of olive oil.

[0030] In the present invention, when the pulse voltage of the high-voltage pulse electric field is 6000-6500V, the pulse width is 30μs, the frequency is 10-75Hz, and the pulse number is 15-30 times, the extracted olive oil has better comprehensive performance in terms of oil yield, acid value, peroxide value and relative content of unsaturated fatty acids.

[0031] In the present invention, the pulse voltage of the high-voltage pulse electric field affects the final oil yield and the relative content of unsaturated fatty acids in olive oil. When the pulse voltage of the high-voltage pulse electric field is 6500V, the oil yield and oil quality of olive oil are optimal.

[0032] In the present invention, the pulse frequency of the high-voltage pulse electric field affects the final oil yield and the relative content of unsaturated fatty acids in olive oil. When the pulse frequency of the high-voltage pulse electric field is 10 Hz, the oil yield and oil quality of olive oil are optimal.

[0033] In the present invention, when the stirring and blending temperature is 28-38° C., the rotation speed is 60 r / min, and the time is 40-50 min, it is more conducive to the stirring and blending of the jam to form a uniform pulp, thereby improving the oil yield and quality of the olive oil.

[0034] In the present invention, when the stirring and fusing temperature is 35° C. and the stirring and fusing time is 45 min, the final oil yield, acid value, peroxide value and relative content of unsaturated fatty acids of olive oil are optimal.

[0035] In the present invention, when the solid-liquid separation speed of the horizontal centrifuge is 5000 r / min and the centrifugation time is 1 min, the oil residue can be removed better, thereby obtaining an oil-water mixed liquid with less impurities.

[0036] Furthermore, when the rotation speed is 5900 r / min and the centrifugal time is 1 min, the oil-water separation effect is the best.

[0037] In the present invention, the horizontal centrifuge can utilize the high-speed rotating drum to generate centrifugal force to trap the solid particles in the suspension in the drum and automatically discharge them out of the machine under the action of force; at the same time, under the action of centrifugal force, the liquid in the suspension is thrown out through the filter medium and the small holes of the drum, thereby achieving the purpose of liquid-solid separation and filtration.

[0038] Disc separators can perform two operations: liquid-solid separation (i.e. separation of low-concentration suspensions), called clarification operations; liquid-liquid separation (or liquid-liquid-solid) separation (i.e. separation of emulsions), called separation operations. A centrifuge with a stack of conical discs installed in the drum that separates emulsions and low-concentration suspension components by centrifugal sedimentation. Disc separators can operate under closed, high-temperature, low-temperature, pressurized and vacuum conditions, and are used to extract cream and juice from milk, purify beer, animal and vegetable oils, transformer oil, etc., as well as concentrate yeast and extract serum from animal plasma.

[0039] Therefore, the present invention uses a horizontal centrifuge for solid-liquid separation and a disc centrifuge for oil-water separation, which can better improve the extraction rate of olive oil.

[0040] The scheme of the present invention will be explained below in conjunction with the embodiments. It will be appreciated by those skilled in the art that the following embodiments are only used to illustrate the present invention and should not be considered as limiting the scope of the present invention. Where specific techniques or conditions are not indicated in the embodiments, the techniques or conditions described in the literature in this area or the product specifications are used. The reagents or instruments used are not indicated by the manufacturer and are all conventional products that can be obtained commercially.

[0041] Determination of various indicators

[0042] (1) Oil yield: Oil yield = weight of oil / weight of fresh fruit.

[0043] (2) Acid value: Determined by cold solvent indicator titration method according to GB5009.229-2016 “National Food Safety Standard - Determination of Acid Value in Food”.

[0044] (3) Peroxide value: Determined by titration method according to GB5009.227-2016 National Food Safety Standard Peroxide Value in Food.

[0045] (4) Determination of main fatty acid composition and relative content

[0046] The fatty acid components of olive oil were detected and analyzed using a GCMS-2010QP gas chromatography-mass spectrometer (Shimadzu Corporation, Japan). The fatty acid composition was determined using the NIST MS mass spectrometry database, and the relative content of each fatty acid was calculated using the peak area normalization method.

[0047] Methylation: Add 2mL of 1mol / mL KOH-methanol solution to 0.10g of oil, shake repeatedly in a 40℃ water bath for 30min, let stand for 15min, add 2mL of n-hexane for extraction, let stand for 10min, take the supernatant, add a little anhydrous sodium carbonate, filter through a 0.45μm microporous membrane for subsequent determination.

[0048] GC-MS analysis conditions

[0049] Gas chromatography conditions: HP-5MS capillary column (30m×0.25mm×0.25μm). Temperature program: 80℃ for 1min, 20℃ / min to 160℃ for 1min, 20℃ / min to 200℃ for 1min, 5℃ / min to 250℃ for 5min. Split ratio 200:1, injection port temperature 250℃, helium as carrier gas, flow rate 1mL / min, injection volume 1μL.

[0050] Mass spectrometry conditions: EI ion source, mass scanning range: 50-500 amu, solvent delay 3 min.

[0051] Example 1

[0052] 1) Wash and crush fresh olive fruits, accurately weigh 500 g of them and perform high-voltage pulse treatment, with a pulse voltage of 6000 V, a pulse width of 30 μs, a frequency of 10 Hz, and a pulse number of 30 times to form jam.

[0053] 2) The jam after the pulse treatment in 1) was stirred and blended at a speed of 60 r / min and 35° C. for 40 minutes to form a pulp.

[0054] 3) The fruit pulp in 2) is subjected to solid-liquid separation treatment at room temperature at 5000 r / min for 1 min using a horizontal centrifuge to obtain an oil-water mixture.

[0055] 4) The oil-water mixture in 3) was separated from the water by a disc centrifuge at a rotation speed of 5900 r / min for 1 min, and the mixture was allowed to stand at 15° C. in a dark and oxygen-free environment to obtain olive oil. The yield of the olive oil was 16.3%, the acid value was 0.39, the peroxide value was 1.04, and the relative content of unsaturated fatty acids was 82.9%.

[0056] Example 2

[0057] 1) Wash and crush fresh olive fruits, accurately weigh 500 g of them and perform high-voltage pulse treatment, with a pulse voltage of 6500 V, a pulse width of 30 μs, a frequency of 10 Hz, and a pulse number of 30 times to form jam.

[0058] 2) The jam after the pulse treatment in 1) was stirred and blended at a speed of 60 r / min and 35° C. for 40 minutes to form a pulp.

[0059] 3) The fruit pulp in 2) is subjected to solid-liquid separation treatment at room temperature at 5000 r / min for 1 min using a horizontal centrifuge to obtain an oil-water mixture.

[0060] 4) The oil-water mixture in 3) was separated from the water by a disc centrifuge at a rotation speed of 5900 r / min for 1 min, and the mixture was kept at 15° C. in a dark and oxygen-free environment to obtain olive oil. The yield of the olive oil was 18.8%, the acid value was 0.36, the peroxide value was 0.89, and the relative content of unsaturated fatty acids was 83.2%.

[0061] Example 3

[0062] 1) Wash and crush fresh olive fruits, accurately weigh 500 g of them and perform high-voltage pulse treatment, with a pulse voltage of 6500 V, a pulse width of 30 μs, a frequency of 10 Hz, and a pulse number of 30 times to form jam.

[0063] 2) The jam after the pulse treatment in 1) was stirred and blended at a speed of 60 r / min and 35° C. for 45 minutes to form a pulp.

[0064] 3) The fruit pulp in 2) is subjected to solid-liquid separation treatment at room temperature using a horizontal centrifuge at 5000 r / min for 1 min to obtain an oil-water mixture.

[0065] 4) The oil-water mixture in 3) was separated from the water by a disc centrifuge at a rotation speed of 5900 r / min for 1 min, and the mixture was kept at 15° C. in a dark and oxygen-free environment to obtain olive oil. The yield of the olive oil was 21.9%, the acid value was 0.34, the peroxide value was 0.72, and the relative content of unsaturated fatty acids was 83.5%.

[0066] Comparative Example 1 was not subjected to high voltage pulse treatment, and other operations and parameters were the same as those of Example 1.

[0067] 1) Wash and crush fresh olive fruits to form jam, accurately weigh 500 g of jam, stir and blend at a speed of 60 r / min and 35° C. for 40 min to form fruit pulp.

[0068] 2) The fruit pulp in 1) is subjected to solid-liquid separation treatment at room temperature using a horizontal centrifuge at 5000 r / min for 1 min to obtain an oil-water mixture.

[0069] 3) The oil-water mixture was separated from the oil-water mixture by a disc centrifuge at a rotation speed of 5900 r / min for 1 min, and the mixture was kept at 15° C. in a dark and oxygen-free environment to obtain olive oil. The yield of the olive oil was 14.2%, the acid value was 0.45, the peroxide value was 1.24, and the relative content of unsaturated fatty acids was 82.5%.

[0070] Comparative Example 2 The high voltage pulse treatment frequency is 5 Hz, and other operations and parameters are the same as those in Example 1

[0071] 1) Wash and crush fresh olive fruits, accurately weigh 500 g of them and perform high-voltage pulse treatment, with a pulse voltage of 6000 V, a pulse width of 30 μs, a frequency of 5 Hz, and a pulse number of 30 times to form jam.

[0072] 2) The jam after the pulse treatment in 1) was stirred and blended at a speed of 60 r / min and 35° C. for 40 minutes to form a pulp.

[0073] 3) The fruit pulp in 2) is subjected to solid-liquid separation treatment at room temperature at 5000 r / min for 1 min using a horizontal centrifuge to obtain an oil-water mixture.

[0074] 4) The oil-water mixture in 3) was separated from the water by a disc centrifuge at a rotation speed of 5900 r / min for 1 min, and the mixture was allowed to stand at 15° C. in a dark and oxygen-free environment to obtain olive oil. The yield of the olive oil was 14.1%, the acid value was 0.43, the peroxide value was 1.11, and the relative content of unsaturated fatty acids was 82.48%.

[0075] Comparative Example 3 The high voltage pulse treatment voltage is 5000V, and other operations and parameters are the same as those in Example 1

[0076] 1) Wash and crush fresh olive fruits, accurately weigh 500 g of them and perform high-voltage pulse treatment, with a pulse voltage of 5000 V, a pulse width of 30 μs, a frequency of 10 Hz, and a pulse number of 30 times to form jam.

[0077] 2) The jam after the pulse treatment in 1) was stirred and blended at a speed of 60 r / min and 35° C. for 40 minutes to form a pulp.

[0078] 3) The fruit pulp in 2) is subjected to solid-liquid separation treatment at room temperature at 5000 r / min for 1 min using a horizontal centrifuge to obtain an oil-water mixture.

[0079] 4) The oil-water mixture in 3) was separated from the water by a disc centrifuge at a rotation speed of 5900 r / min for 1 min, and the mixture was allowed to stand at 15° C. in a dark and oxygen-free environment to obtain olive oil. The yield of the olive oil was 13.8%, the acid value was 0.39, the peroxide value was 1.00, and the relative content of unsaturated fatty acids was 82.4%.

[0080] Table 1 Fatty acid composition and relative content of different embodiments and comparative examples

[0081]

[0082]

[0083] Note: Saturated fatty acids include palmitic acid, stearic acid, and arachidic acid; unsaturated fatty acids include palmitoleic acid, oleic acid, linoleic acid, and heptadecenoic acid.

[0084] From the above experimental results, it can be seen that compared with Comparative Example 1 (existing traditional process), the present invention adopts high-voltage pulse treatment to increase the oil yield of olive oil from 14.2% to 16.3% to 21.9%, the acid value is reduced from 0.45 to 0.34 to 0.39, the peroxide value is reduced from 1.24 to 0.72 to 1.04, and the relative content of unsaturated fatty acids is increased from 82.5% to 82.9% to 83.5%. At the same time, when the pulse voltage is 6000 to 6500V, the pulse width is 30μs, and the frequency is 10 to 75Hz, the oil yield and olive oil quality are better. It can be seen that the method of the present invention can greatly improve the oil yield of olive oil and improve the quality of olive oil.

[0085] It should be noted that the specific features, structures, materials or characteristics described in this specification may be combined in any one or more embodiments in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments and features of the different embodiments described in this specification without contradicting each other.

Claims

1. A method for extracting olive oil, characterized in that: The following steps are involved: After washing and crushing the olive fruits, high-voltage pulse treatment with a voltage of 6000-6500 V, a pulse width of 30 μs, a frequency of 10-75 Hz, and a pulse number of 15-30 times, stirring and fusion, solid-liquid separation, oil-water separation, and standing are sequentially performed.

2. The method for extracting olive oil according to claim 1, characterized in that: The stirring and fusion is performed at a temperature of 28 to 38° C., a rotation speed of 60 r / min, and a time of 40 to 50 min.

3. The method for extracting olive oil according to claim 1, characterized in that: The solid-liquid separation adopts a horizontal centrifuge with a separation speed of 5000 r / min and a centrifugal time of 1 min.

4. The method for extracting olive oil according to claim 1, characterized in that: The oil-water separation adopts a disc centrifuge with a separation speed of 5900 r / min and a centrifugal time of 1 min.

5. The method for extracting olive oil according to claim 1, characterized in that: The static conditions are light-proof, oxygen-proof, and a temperature of 15 to 18°C.

6. The method for extracting olive oil according to any one of claims 1 to 5, characterized in that: The olive fruit is fresh olive fruit.

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