Defatted coconut flour based oil gel and method of making same

Abstract

The application belongs to the field of food processing, and particularly relates to a defatted coconut powder-based oil gel and a preparation method thereof. First, defatted coconut powder is ground and dissolved in a solution to form a defatted coconut powder solution, then the defatted coconut powder solution is mixed with vegetable oil at different proportions, homogenized and emulsified, then the emulsified solution is pre-cooled and frozen at low temperature, then vacuum freeze-drying is carried out at -60 DEG C, and finally the freeze-dried sample is subjected to low-speed shearing to obtain the defatted coconut powder-based oil gel. The defatted coconut powder selected in the application is a compound of dietary fiber and coconut protein, and compared with other polysaccharide protein compound gels, has the advantages of easy raw material acquisition, simple preparation process, wide application range, and reduced production cost.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of food processing, and particularly relates to a defatted coconut powder-based oil gel and a preparation method thereof. BACKGROUND

[0002] Oil gel is a polymer gel-like material formed by encapsulating liquid oil in crystalline particles or a three-dimensional network structure. The preparation methods of oil gel can be roughly divided into two types: direct method and indirect method. The oil gel prepared by the direct method has poor waxy aroma and high melting temperature, which poses challenges in the application of the food industry. Therefore, the indirect method involving the use of hydrophilic colloids such as proteins and polysaccharides as gel factors to form a three-dimensional polymer network structure has attracted more and more attention.

[0003] At present, a number of patent documents record the content of oil gel prepared by single protein / polysaccharide or their complex. For example, Chinese invention patent CN116420868A discloses a preparation method of a plant-based fat substitute rich in dietary fiber. The method compounding soluble dietary fiber in bean dregs with soybean protein at different proportions, and forming a fiber-rich soybean protein oil gel fat substitute through heat induction. Although the process has a fat-like taste, the extraction process of fiber and protein is complex, and the long time of high temperature in the heat induction process can accelerate the oxidation of oil, thereby reducing the nutritional value of the oil gel. Chinese invention patent CN114467997B discloses a preparation and application of a composite double-network zero-trans low-saturated fatty acid oil gel. The invention uses water-soluble polysaccharide as the raw material for constructing a biopolymer network, prepares water foam from the water-soluble polysaccharide, removes water from the water foam to obtain a porous aerogel, then uses the porous aerogel to absorb oil-soluble small molecules or oil after heating, and finally cools and homogenizes the oil-absorbed aerogel to obtain a composite double-network zero-trans low-saturated fatty acid oil gel. The invention has a high requirement for the foaming property of polysaccharide, and the heating of oil in the preparation process can reduce the nutritional value of the oil gel, and high-concentration glyceryl monostearate is difficult to be accepted by consumers. Therefore, based on the above problems, it is particularly important to innovate a kind of edible oil gel with simple preparation process and high nutritional value. SUMMARY

[0004] To solve the above problems, the present application provides a preparation method of a defatted coconut powder-based oil gel, comprising the following steps:

[0005] (1) mixing defatted coconut powder with water to form a defatted coconut powder solution, adding vegetable oil, and homogenizing and emulsifying to form an emulsified solution;

[0006] (2) pre-freezing the emulsified solution, and then vacuum freeze-drying the emulsified solution at-60℃;

[0007] (3) the defatted coconut powder based oil gel is obtained by low speed shearing of the freeze-dried sample.

[0008] Further, the water in step (1) is distilled water or ultrapure water.

[0009] Further, the concentration of the defatted coconut powder solution in step (1) is 2.5% to 12.5% by weight.

[0010] Further, the vegetable oil in step (1) is corn oil.

[0011] Further, the ratio of the defatted coconut powder solution and the vegetable oil in step (1) is 3:7 or 4:6 or 5:5.

[0012] Further, the pre-freezing condition of the defatted coconut powder emulsion in step (2) is -20 DEG C for 24 hours, and the freeze-drying condition is -60 DEG C for 48 hours.

[0013] Further, the low speed shearing condition of the freeze-dried sample in step (2) is 500 rpm for 2 minutes.

[0014] The application also provides a defatted coconut powder based oil gel prepared by the above method.

[0015] The application has the following beneficial effects:

[0016] (1) The raw material selected in the application is defatted coconut powder, which is a byproduct after pressing oil from coconut meat. Although the yield is large, the utilization rate is low. The present study provides a new direction for the high-value utilization of defatted coconut powder.

[0017] (2) The defatted coconut powder selected in the application is a complex of dietary fiber and coconut protein. Compared with other polysaccharide protein composite gels, the raw material is easy to obtain, the preparation process is simple, the application range is wide, and the production cost is reduced.

[0018] (3) The defatted coconut powder based oil gel prepared in the application has excellent oil holding capacity, texture and rheological properties. The content of defatted coconut powder can be adjusted to adjust the properties of the oil gel according to actual needs. BRIEF DESCRIPTION OF DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the application or the prior art, the following will briefly introduce the drawings needed in the embodiments. Obviously, the drawings in the following description are only some embodiments of the application, and other drawings can be obtained by those skilled in the art without creative labor.

[0020] Figure 1 Preparation process of the defatted coconut powder based oil gel of the application;

[0021] Figure 2 Macroscopic (A) and microscopic structure images (B, optical microscopy pictures; C, polarized light microscopy pictures) of lyophilized samples of oil gels of different systems;

[0022] Figure 3 Oil holding capacity of oil gels of different systems;

[0023] Figure 4 Rheological properties of oil gels of different systems (A, frequency sweep; B, strain sweep; C, viscosity; D, 3ITT). DETAILED DESCRIPTION

[0024] Various exemplary embodiments of the present application are described in detail herein, and the methods of the examples follow conventional methods unless otherwise specified, and the reagents used are conventional commercially available reagents or reagents prepared by conventional methods unless otherwise specified. This detailed description is not to be taken in a limiting sense, but is made merely for illustrating some aspects, features and embodiments of the present application.

[0025] It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present application. Additionally, it is to be understood that where the application is herein described as comprising or having particular elements, this is intended to mean that the application encompasses or has at least those particular elements. In other words, the words "comprising" and "having" are to be interpreted broadly to include the presence of at least the stated elements. In addition, it is to be understood that the numerical ranges herein are to be interpreted as "from 'lower limit of range' to 'upper limit of range'".

[0026] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. Although preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present application. All documents mentioned herein are incorporated by reference to disclose and describe the methods and / or materials in connection with which the documents are cited. In case of conflict between the present specification and any document incorporated by reference, the present specification will control.

[0027] Various modifications and changes can be made to the specific embodiments of the present application described herein without departing from the scope or spirit of the application. Other embodiments of the application will be apparent to those of ordinary skill in the art from the description and examples herein. The description and examples are illustrative of the application and are not intended to limit the scope of the application.

[0028] As used herein, the terms "comprise", "comprising", "include", "including", "have", "having" or variants thereof are open-ended, and include one or more of the elements, integers, components or steps of which they precede.

[0029] Example 1

[0030] Precisely weigh the defatted coconut powder, prepare 20 ml of defatted coconut powder solution with a mass fraction of 2.5%, add 20 ml of corn oil, use a high-speed homogenizer, homogenize and emulsify at 7000 rpm for 2 min. Pour the emulsified emulsion into a culture dish, freeze at -20℃ for 24 h, then vacuum freeze dry at -60℃ for 48 h. Finally, use a homogenizer to shear the freeze-dried sample at 500 rpm for 2 min to obtain an oil gel.

[0031] Example 2

[0032] Precisely weigh the defatted coconut powder, prepare 40 ml of defatted coconut powder solution with a mass fraction of 5%, add 60 ml of corn oil, use a high-speed homogenizer, homogenize and emulsify at 7000 rpm for 2 min. Pour the emulsified emulsion into a culture dish, freeze at -20℃ for 24 h, then vacuum freeze dry at -60℃ for 48 h. Finally, use a homogenizer to shear the freeze-dried sample at 500 rpm for 2 min to obtain an oil gel.

[0033] Example 3

[0034] Precisely weigh the defatted coconut powder, prepare 30 ml of defatted coconut powder solution with a mass fraction of 7.5%, add 70 ml of corn oil, use a high-speed homogenizer, homogenize and emulsify at 7000 rpm for 2 min. Pour the emulsified emulsion into a culture dish, freeze at -20℃ for 24 h, then vacuum freeze dry at -60℃ for 48 h. Finally, use a homogenizer to shear the freeze-dried sample at 500 rpm for 2 min to obtain an oil gel.

[0035] Experimental Case 1: Microstructure Experiment

[0036] The oil gels prepared in Example 1, Example 2, and Example 3 were used as experimental samples. The appearance was observed, and the microstructure of the network was observed by optical microscope and polarized light microscope.

[0037] By Figure 2 It can be seen that the oil gel with low content of defatted coconut powder has a light yellow appearance and is a semi-solid, which is relatively soft. With the increase of the content of defatted coconut powder, the appearance of the oil gel tends to be milky white, and gradually becomes hard. The microstructure results show that the network structure of the oil gel prepared with low concentration of defatted coconut powder is relatively sparse, while with the increase of the concentration, the network structure gradually becomes compact and presents a relatively coarse particulate shape.

[0038] Experimental Case 2: Oil Retention Capacity Experiment

[0039] The oil gels prepared in Example 1, Example 2, Example 3 were used as experimental samples, 1 g was taken in a centrifuge tube, centrifuged at 25 °C, 10000 rpm for 10 min, the leaked oil was discarded, and weighed. The oil holding capacity of the oil gel was calculated according to the following formula:

[0040]

[0041] By Figure 3 It can be seen that the oil holding capacity of the oil gel increases significantly with the increase of the concentration of defatted coconut powder. The oil gel stabilized by high concentration of defatted coconut powder has an oil holding capacity of more than 95%, which has excellent oil holding capacity.

[0042] Experimental case 3: Rheological property experiment

[0043] The rheological properties of the oil gel samples were determined by MCR 92 rotational rheometer (MCR 92, Anton Paar, Austria) equipped with a Peltier temperature control system. The measurement system used a plate / plate geometry PP50 with a diameter of 50 mm. The amplitude sweep of all samples was measured by strain sweep test (0.1%-100%) at a fixed frequency of 1.0 Hz. The strain test was carried out at 25 °C, 0.1% strain, in the frequency range of 0.1 Hz-100 Hz. The apparent viscosity was obtained at the shear rate in the range of 0.1 s -1 to 100 s -1 . Thixotropy test (3-ITT) was determined by detecting the change of viscosity with time when the shear rate changed (the shear rate was 0.1 s -1 , 10.0 s -1 , 0.1 s -1 , each test rate was 600 s).

[0044] Frequency sweep ( Figure 4 A) and strain results ( Figure 4 B) show that all samples exhibit solid morphology (G'>G") and are easily deformed under stress. Higher concentration of defatted coconut powder leads to more compact structure of oil gel, with higher G' and yield strain value, indicating stronger network structure. Compared with oil gels constructed by other polysaccharide or protein factors, defatted coconut powder-based oil gels have higher gel strength (G') and yield strain.

[0045] Apparent viscosity results ( Figure 4C) shows that the higher the concentration of defatted coconut powder, the faster the apparent viscosity of the oil gel decreases with the increase of shear rate. That is, the behavior of the oil gel pseudoplastic fluid is more obvious. At the same shear frequency, the apparent viscosity of the oil gel increases with the increase of the concentration of defatted coconut powder, indicating that a higher concentration of defatted coconut powder can promote the self-assembly structure inside the oil gel to be more compact, thereby improving its shear resistance.

[0046] 3-ITT results Figure 4 D) shows that the viscosity of the oil gel sample slowly decreases with time at a constant shear rate, indicating that the behavior has a time dependence. When the shear rate is sharply reduced from 10 s -1 to 0.1 s -1 , the viscosity of the sample immediately increases, indicating that it has good structure recovery properties. Since the oil gel can recover its function and mechanical properties, it shows potential application prospects in food products that require shearing during manufacturing.

[0047] The above-described embodiments are only descriptions of the preferred modes of the present application and do not limit the scope of the present application. Without departing from the design spirit of the present application, various modifications and improvements to the technical solutions of the present application made by those skilled in the art shall fall within the protection scope determined by the claims of the present application.

Claims

1. A process for the preparation of defatted coconut flour based oil gel characterized in that, The method comprises the following steps: (1) preparing a defatted coconut powder solution by mixing defatted coconut powder with water, and adding vegetable oil to homogenize and emulsify the solution; (2) pre-freezing the emulsified solution, and then vacuum freeze-drying the emulsified solution at -60℃; (3) low-speed shearing the freeze-dried sample to obtain a defatted coconut powder-based oil gel; The low-speed shearing condition of the freeze-dried sample in step (3) is 500 rpm for 2 min; The concentration of the defatted coconut powder solution in step (1) is 2.5%-12.5% by weight; The ratio of the defatted coconut powder solution to the vegetable oil in step (1) is 3:7, 4:6 or 5:

5.

2. The production method according to claim 1, characterized by, The water in step (1) is distilled water or ultrapure water.

3. The preparation method according to claim 1, characterized in that, The vegetable oil in step (1) is corn oil.

4. The production method according to claim 1, characterized by, The pre-freezing condition of the defatted coconut powder emulsion in step (2) is -20℃ for 24 h, and the freeze-drying condition is -60℃ for 48 h.

5. A defatted coconut flour based oil gel characterized in that, Prepared by the method of any one of claims 1-4.

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