Rice bran cyclone separation process

Abstract

The invention relates to a rice bran cyclone separation process. The method comprises the following steps: crushing rice bran, and performing ultrasonic treatment, vacuum filtration and drying to obtain defatted rice bran; and putting the defatted rice bran into a constant-temperature and constant-humidity box, adjusting the moisture content, and carrying out cyclone separation to obtain a target product. Optimization conditions of the rice bran cyclone separation process are obtained through experiments, and when the flow is 9 kg / h, the fan frequency is 60 Hz and the rice bran moisture content is 6.18%, the recovery rate of a secondary opening of a cyclone separator reaches 7.38%. Different rice bran components obtained through cyclone separation are more uniform in physical property and more remarkable in chemical component difference, grading processing and utilization of the rice bran are facilitated, and technical support is provided for industrial production of the rice bran.

Description

Technical Field

[0001] The invention relates to a rice bran cyclone separation process and belongs to the field of food processing. Background Art

[0002] Rice bran contains a variety of bioactive substances and nutrients, including vitamins, proteins, phenolic compounds and trace minerals. For a long time, rice bran has often been used as feed or directly discarded, resulting in a high-value utilization rate of less than 20%. This not only causes a huge waste of rice bran resources, but also limits the development of its potential value. At present, the main domestic research is to analyze and study the processing quality of rice and the nutritional components of rice bran, usually for centralized recycling and mixed utilization. Grading rice bran is the key to improving the value of subsequent processing and utilization.

[0003] The coarse and fine bran are separated by the air selection system and used separately to improve the utilization efficiency of rice bran and the quality of the product. Airflow classification can be used to grade wheat flour and separate protein-rich components from soybean powder. Cyclone separation is a type of airflow classification. Under the centrifugal force generated by high-speed rotating airflow, particles of different sizes or densities have different settling speeds, thereby separating the material from the airflow. Cyclone separation is widely used in food, chemical and other industries, but there is very little research on cyclone separation of rice bran at home and abroad.

[0004] Therefore, it is necessary to further study the separation and research of rice bran components by cyclone separation to promote practical applications. Summary of the invention

[0005] In order to solve the above technical problems, the present invention provides a rice bran cyclone separation process.

[0006] The technical solution adopted by the present invention is:

[0007] A rice bran cyclone separation process comprises the following steps:

[0008] (1) crushing rice bran and sieving it, weighing the crushed rice bran and putting it into a container, adding anhydrous ethanol at a solid-liquid ratio of 1:10-15 g / mL, performing ultrasonic treatment, and then vacuum filtering and drying to obtain defatted rice bran;

[0009] (2) putting the defatted rice bran into a constant temperature and humidity chamber, adjusting its moisture content, and performing cyclone separation to obtain the target product.

[0010] The conditions of rice bran defatting in step (1) are: solid-liquid ratio 1:10-15 g / mL, ultrasonic treatment time 30-50 min, ultrasonic temperature 50-70° C., ultrasonic power 100-175 W, vacuum degree 0.08-0.12 MPa during vacuum filtration, and drying condition drying at 100-105° C. for 10-20 min.

[0011] The optimal conditions for rice bran degreasing are: the solid-liquid ratio of rice bran to anhydrous ethanol is 1:15 g / mL, the ultrasonic treatment time is 40 min, the treatment temperature is 70°C, the ultrasonic power is 175 W, the vacuum degree is 0.1 MPa, and the drying conditions are 105°C and drying for 15 min.

[0012] The conditions of the defatted rice bran cyclone separation in step (2) are as follows: the rice bran flow rate is 5.4-12.6 kg / h, the fan frequency is 40-60 Hz, and the rice bran moisture content is 3.11-9.05%.

[0013] The optimal conditions for cyclone separation of defatted rice bran are: rice bran flow rate of 9 kg / h, fan frequency of 60 Hz, and moisture content of rice bran before treatment of 6.18%.

[0014] Beneficial effects of the present invention

[0015] (1) The present invention uses ultrasound-anhydrous ethanol to defatted rice bran, and separates the defatted rice bran into different components by cyclone separation, which is beneficial to the classification and processing of rice bran. The cyclone separation process is simple to operate, convenient and fast, and has a certain reference role in the accurate classification and research of rice bran, which will promote the structural adjustment of rice bran in the rice processing industry and improve the overall benefits.

[0016] (2) The rice bran obtained by cyclone separation of the present invention has a secondary outlet rice bran protein and total dietary fiber content increased by 46.02% and 34.26% respectively compared with the rice bran raw material. 50 It dropped from 220.00μm to 12.60μm; the water solubility index and swelling power increased by 70.06% and 99.53% respectively; the content of flavonoids and polyphenols with antioxidant properties also increased.

[0017] (3) The present invention significantly improves the physical properties of rice bran through cyclone separation, and the nutritional value is effectively improved. This is not only conducive to the subsequent processing and utilization of rice bran in the food field, but also provides technical support for the industrial production of rice bran. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 Effect of solid-liquid ratio on rice bran degreasing rate;

[0019] Figure 2 The effect of ultrasonic time on the degreasing rate of rice bran;

[0020] Figure 3 The effect of ultrasonic temperature on the degreasing rate of rice bran;

[0021] Figure 4 Effect of ultrasonic power on rice bran degreasing rate;

[0022] Figure 5The effect of rice bran flow rate on the recovery rate of the secondary port of the cyclone separator;

[0023] Figure 6 The effect of fan frequency on the recovery rate of the secondary port of the cyclone separator;

[0024] Figure 7 The effect of rice bran moisture content on the recovery rate of the secondary port of the cyclone separator;

[0025] Figure 8 Comparison of water holding capacity, oil holding capacity, water solubility index and swelling power of graded rice bran samples. DETAILED DESCRIPTION

[0026] The technical solution of the present invention is further described in detail below in conjunction with specific embodiments.

[0027] Example 1 Optimization of ultrasonic degreasing process of rice bran

[0028] 1.1 Single factor test of ultrasonic degreasing of rice bran

[0029] The crushed rice bran was weighed and anhydrous ethanol was added into a beaker according to different solid-liquid ratios (1:5, 1:7.5, 1:10, 1:12.5, 1:15 g / mL). The rice bran was ultrasonically degreased under the conditions of ultrasonic time (20, 30, 40, 50, 60 min), ultrasonic temperature (30, 40, 50, 60, 70°C) and ultrasonic power (100, 125, 175, 225, 250 W). The effects of these four factors on the degreasing effect of rice bran were investigated.

[0030] The rice bran is vacuum filtered and dried to obtain defatted rice bran. The vacuum degree of the filtration is 0.1Mpa, and the rice bran is dried at 105°C for 15 minutes.

[0031] The results of the single factor experiment are as follows Figure 1 to Figure 4 As shown, when the solid-liquid ratio is in the range of 1:5-1:12.5 g / mL, the degreasing rate increases with the increase of the amount of anhydrous ethanol. When the solid-liquid ratio reaches 1:12.5 g / mL, the maximum degreasing rate is 88.97%; with the extension of ultrasonic time, the degreasing rate shows a trend of first increasing and then decreasing. When the ultrasonic time is 40 min, the degreasing rate is the best, reaching 89.04%; when the ultrasonic temperature is 60 ° C, the maximum degreasing rate is 86.26%; when the ultrasonic power is 125 W, the degreasing rate is the best, reaching 93.81%.

[0032] Therefore, the suitable conditions for ultrasonic treatment of rice bran are preliminarily obtained as follows: solid-liquid ratio 1:10-15 g / mL, ultrasonic time 30-50 min, ultrasonic temperature 50-70 °C, and ultrasonic power 100-175 W.

[0033] 1.2 Orthogonal optimization test

[0034] On the basis of the single factor experiment in 1.1, the material-liquid ratio (A), ultrasonic time (B), ultrasonic temperature (C) and ultrasonic power (D) were selected as factors, and the degreasing rate was used as an indicator to carry out orthogonal optimization experiments. The results are shown in Table 1.

[0035] Table 1 Factors and levels of orthogonal experimental design for ultrasonic degreasing of rice bran

[0036]

[0037] Based on the single factor experiment, L9(4 3 )Orthogonal experimental design table was used to optimize the process of ultrasonic degreasing of rice bran. The experimental results are shown in Table 2.

[0038] Table 2 Orthogonal test results of ultrasonic degreasing of rice bran

[0039]

[0040] Note: K value represents the sum of indicators at each level of each factor.

[0041] From the orthogonal test range analysis, it can be seen that the order of influence factors of ultrasonic degreasing is: material-liquid ratio (A) > ultrasonic temperature (C) > ultrasonic power (D) > ultrasonic time (B).

[0042] From Table 2, the best experimental combination of degreasing process is: A 3 B 2 C 3 D 3 That is, anhydrous ethanol was added at a solid-liquid ratio of 1:15g / mL, and the process was carried out for 40 minutes under the conditions of ultrasonic power of 175W and ultrasonic temperature of 70℃. After three parallel measurements, the degreasing rate was 96.22%, which was higher than the degreasing rate of test No. 8.

[0043] Example 2 Optimization of defatted rice bran cyclone separation process

[0044] 2.1 Defatted rice bran cyclone separation process

[0045] The prepared defatted rice bran was placed in a constant temperature and humidity chamber (temperature 25°C, relative humidity 80%) to adjust the moisture content. Under the conditions of rice bran flow rate (1.8, 5.4, 9.0, 12.6 kg / h), fan frequency (30, 40, 50, 60 Hz), and rice bran moisture content (3.11, 6.18, 9.05, 12.10%), the defatted rice bran was cyclone separated for 2 min to investigate the influence of these three factors on the defatted rice bran cyclone separation efficiency.

[0046] The results of the single factor experiment are as follows Figure 5 to Figure 7As shown. Within the flow rate range of 1.8-12.6kg / h, the recovery rate at the secondary port of the cyclone separator increases first and then decreases with the increase of flow rate; when the flow rate reaches 9.0kg / h, the maximum recovery rate at the secondary port of the cyclone separator is 6.13%. As the fan frequency continues to increase, the recovery rate at the secondary port of the cyclone separator gradually increases. When the fan frequency reaches 60Hz, the recovery rate gradually stabilizes. At this time, the recovery rate at the secondary port of the cyclone separator reaches 6.70%. When the moisture content increases, the recovery rate at the secondary port of the cyclone separator increases first and then decreases. When the moisture content is 6.18%, the recovery rate at the secondary port of the cyclone separator is the best, reaching 6.88%.

[0047] Therefore, the preliminary suitable conditions for cyclone separation of defatted rice bran are: flow rate 5.4-12.6 kg / h, fan frequency 40-60 Hz, and rice bran moisture content 3.11-9.05%.

[0048] 2.2 Orthogonal optimization experiment

[0049] On the basis of the single factor experiment in 2.1, flow rate (A), fan frequency (B) and moisture content (C) were selected as factors, and the recovery rate at the secondary port of the cyclone separator was used as an indicator to carry out an orthogonal optimization experiment. The results are shown in Table 3.

[0050] Table 3 Factors and levels of orthogonal experimental design for cyclone separation of defatted rice bran

[0051]

[0052] Based on the single factor experiment, L9(4 3 )Orthogonal experimental design table was used to optimize the process of cyclone separation of defatted rice bran. The experimental results are shown in Table 4.

[0053] Table 4 Orthogonal test results of defatted rice bran cyclone separation

[0054]

[0055] Note: K value represents the sum of indicators at each level of each factor.

[0056] From the range analysis of orthogonal test, it can be seen that the order of influence factors of defatted rice bran cyclone separation is: moisture content (C) > fan frequency (B) > flow rate (A) > blank (D). Blank (D) is the comparison without any experimental factors in the orthogonal table.

[0057] Therefore, the best experimental theoretical combination of defatted rice bran cyclone separation process is A 2 B 3 C 2 D 3, under the conditions of flow rate of 9.0kg / h, moisture content of 6.18% and fan frequency of 60Hz, a cyclone separator was used to grade rice bran. After three parallel measurements, the secondary port recovery rate of the cyclone separator was 7.38%, which was higher than the secondary port recovery rate of the cyclone separator in test No. 9.

[0058] Example 3 Performance of Rice Bran Treated with Ultrasonic Degreasing and Cyclone Separation

[0059] 3.1 Basic components of rice bran graded samples

[0060] The basic components of the graded rice bran were determined, and the results are shown in Table 5.

[0061] Table 5 Basic component content of rice bran classification samples (%)

[0062]

[0063] Note: 1. Different lowercase letters in the upper right corner of the same column represent significant differences (P<0.05).

[0064] 2.The contents of components in the table are on a dry basis.

[0065] In Table 5, the rice bran treated differently is represented by codes: Z, represents rice bran sieved through a 40-mesh standard sieve; X0, rice bran defatted by ultrasonic wave and anhydrous ethanol; X1, rice bran collected from the first port of a cyclone separator; X2, rice bran collected from the second port of a cyclone separator.

[0066] As shown in Table 5, compared with rice bran Z, the fat content in rice bran after ultrasonic treatment decreased from 14.37% to 1.19%, and the protein, ash and total dietary fiber content in rice bran increased significantly. The protein, ash and total dietary fiber content of rice bran X2 collected from the secondary port increased by 46.02%, 202.08% and 34.26% respectively compared with rice bran Z. Compared with Z, the starch content of X0 and X1 increased significantly, and the starch content of X1 was the largest, reaching 34.96%.

[0067] 3.2 Determination of physical properties of rice bran

[0068] 3.2.1 Particle size determination

[0069] The particle size and distribution of the sample were measured using a laser particle size analyzer. 10 , D 50 , D 90 Particle size, which represents the particle size corresponding to the cumulative particle size distribution percentage of the sample reaching 10%, 50% and 90%.

[0070] The calculation formula of the particle size span of rice bran classification sample is: particle size span = (D 90 -D10 ) / D 50 The measurement results are shown in Table 6.

[0071] Table 6 Particle size of rice bran classification samples

[0072]

[0073] Note: Different lowercase letters in the upper right corner of the same column represent significant differences (P<0.05).

[0074] As shown in Table 6, the particle size of X2 is significantly smaller than that of other samples. 90 Reach 43.90μm, D 50 The particle size span reflects the uniformity of the particle size distribution. The smaller the value, the more uniform the particle size distribution. The span of X2 is significantly larger than that of other samples, indicating that its particle size distribution is less uniform. However, the specific surface area of ​​X2 is significantly increased, from 156.70 μm to 2.60 μm. 2 / kg reaches 650.30m 2 / kg, indicating that the particles have good dispersion and can be mixed more evenly with other powders or additives.

[0075] 3.2.2 Determination of hydration characteristics

[0076] (1) Water / oil holding capacity measurement

[0077] The rice bran sample was dispersed in deionized water and corn oil at a ratio of 0.05:1 (w:v) and placed in a water bath at 60°C for 30 min. The mixture was centrifuged at 4000 r / min for 20 min, the supernatant was removed, and the mass of the centrifuge tube containing the precipitate was measured.

[0078] The calculation formulas for water holding capacity and oil holding capacity are as follows:

[0079] Where: m 0 is the sample mass (g), m 1 Centrifuge tube mass (g), m 2 is the mass of the centrifuge tube containing the precipitate (g).

[0080] (2) Determination of water solubility index

[0081] The water solubility index was determined according to AACC 44-15A. The rice bran sample was dispersed in a centrifuge tube with deionized water at a ratio of 1:50 (w:v), mixed and placed in a water bath at 80°C for 30 min. Centrifuged at 4000 r / min for 20 min, the supernatant was poured into an evaporating dish with constant weight, and dried at 105°C to constant weight.

[0082] Water solubility index calculation formula:

[0083] Where: m 0 is the sample mass (g), m 1 is the mass of the evaporating dish (g), m 2 is the mass of the evaporating dish containing the precipitate (g).

[0084] (3) Expansion force

[0085] Take 0.3g rice bran sample, put it into a 10mL graduated test tube, add 6mL deionized water, mix thoroughly, and let stand at room temperature for 20h. Swelling force calculation formula:

[0086] Where: m 0 is the sample mass (g), V 1 is the sample volume (mL), V 2 It is the volume of the sample after it absorbs water and expands (mL).

[0087] The results of the hydration characteristics test of rice bran graded samples are as follows Figure 8 shown.

[0088] Depend on Figure 8 It can be seen that the water holding capacity of the four different rice bran samples is significantly different. The water holding capacity reflects the water retention capacity. From Z to X2, the water holding capacity increases from 3.06g / g to 4.21g / g. However, there is no significant difference in the oil holding capacity of the four different rice bran samples. The water solubility index and swelling power of the rice bran samples separated by cyclone increased significantly. The water solubility index from Z to X2 increased from 20.91% to 35.56%, that is, the water solubility index of X2 increased by 70.06%. Compared with Z, the swelling power of X2 increased by 99.53%. Different lowercase letters in the figure represent significant differences (P<0.05).

[0089] 3.3 Determination of minerals in rice bran

[0090] (1) Heavy metal determination

[0091] Cadmium, chromium and lead were determined with reference to GB5009.268-2016. The results are shown in Table 7.

[0092] Table 7 Heavy metal content of rice bran graded samples (mg / kg)

[0093]

[0094] Note: 1. Different lowercase letters in the upper right corner of the same column represent significant differences (P<0.05).

[0095] 2. Standard GB 2762-2022 stipulates that the maximum residual amounts of cadmium and chromium in grain milling products are 0.1 mg / kg and 1 mg / kg respectively, and the maximum residual amount of lead in grains and their products is 0.2 mg / kg.

[0096] As shown in Table 7, referring to the above standards, the cadmium content of the four different rice bran samples did not exceed the maximum residual amount. Compared with Z, the lead content of X0, X1 and X2 was significantly reduced, and the lead content of X2 was within the safe range.

[0097] (2) Determination of trace elements and major elements

[0098] Referring to GB5009.268-2016 standard, selenium, zinc, copper, iron, calcium, magnesium and potassium elements in graded rice bran samples were determined. The results are shown in Table 8.

[0099] Table 8 Content of trace elements and macroelements in graded rice bran samples (mg / kg)

[0100]

[0101] Note: Different lowercase letters in the upper right corner of the same column represent significant differences (P<0.05).

[0102] As shown in Table 8, the magnesium and potassium contents of the rice bran graded samples were significantly different. After cyclone separation, the contents of the six essential elements (zinc, copper, calcium, iron, magnesium and potassium) in X0, X1 and X2 were significantly increased compared with Z, especially X2, which had the highest content. The contents of zinc, copper, calcium, iron, magnesium and potassium in X2 were 1.36, 1.54, 1.98, 2.35, 3.40 and 2.77 times that of Z, respectively.

[0103] (3) Determination of flavonoids and polyphenols

[0104] Weigh 0.1 g of sample into a 2 mL centrifuge tube, add 1 mL of methanol (analytical grade), and extract at 60 °C for 4 h. Take 0.5 mL of crude extract, add 4.5 mL of methanol; then add 0.3 mL of 5% NaNO 2 The solution was allowed to stand at room temperature for 5 min; then 0.3 mL of 10% AlCl 3 The solution was allowed to stand for 6 minutes; finally, 4 mL of 1 mol / L NaOH was added, the volume was made up to 10 mL with water, and the solution was allowed to stand for 15 minutes, and finally the absorbance was measured at 510 nm.

[0105] Weigh 0.25g rice bran, add 0.5mL 80% methanol aqueous solution (containing 0.2% vitamin C) to mix, extract at room temperature for 30min by ultrasonic wave, centrifuge at 12000rpm for 10min, take supernatant, repeat extraction twice, merge and mix twice supernatant, dilute or concentrate if necessary, take supernatant to be measured.Use ultra-high performance liquid chromatography (UPLC) to analyze the content of polyphenols in the extract, the chromatographic column is Waters HSS T3 (50×2.1mm, 1.8μm), flow velocity is 0.3mL / min, column temperature is 40℃, sample volume is 2μL, mobile phase: A phase is ultrapure water solution (containing 0.1% formic acid), B phase is acetonitrile solution (containing 0.1% formic acid), and gradient elution is carried out.

[0106] The results of the determination of flavonoids and polyphenols in the graded rice bran samples are shown in Table 9.

[0107] Table 9 Flavonoids and polyphenols content of rice bran graded samples

[0108]

[0109] Note: Different lowercase letters in the upper right corner of the same row represent significant differences (P<0.05).

[0110] As shown in Table 9, the total flavonoids and total polyphenols contents of X2 increased by 9.1% and 89.45% respectively compared with Z. After cyclone separation, the contents of protocatechuic acid, protocatechuic aldehyde, vanillin, syringaldehyde, rutin and daidzein increased significantly, especially the contents of protocatechuic aldehyde and rutin in X2 were 3.00 and 2.59 times that of Z respectively.

Claims

1. A rice bran cyclone separation process, characterized in that, The following steps are involved: (1) crushing rice bran and sieving it, weighing the crushed rice bran and putting it into a container, adding anhydrous ethanol at a solid-liquid ratio of 1:10-15 g / mL, performing ultrasonic treatment, and then vacuum filtering and drying to obtain defatted rice bran; (2) putting the defatted rice bran into a constant temperature and humidity chamber, adjusting its moisture content, and performing cyclone separation to obtain the target product.

2. The process according to claim 1, characterized in that The conditions of rice bran defatting in step (1) are: solid-liquid ratio 1:10-15 g / mL, ultrasonic treatment time 30-50 min, ultrasonic temperature 50-70° C., ultrasonic power 100-175 W, vacuum degree 0.08-0.12 MPa during vacuum filtration, and drying condition drying at 100-105° C. for 10-20 min.

3. The process according to claim 2, characterized in that The conditions of step (1) rice bran defatting are: a solid-liquid ratio of rice bran to anhydrous ethanol of 1:15 g / mL, an ultrasonic treatment time of 40 min, a treatment temperature of 70 ° C, an ultrasonic power of 175 W, a vacuum degree of 0.1 MPa, and a drying condition of 105 ° C and drying for 15 min.

4. The process according to claim 1, characterized in that The conditions of the defatted rice bran cyclone separation in step (2) are as follows: the rice bran flow rate is 5.4-12.6 kg / h, the fan frequency is 40-60 Hz, and the rice bran moisture content is 3.11-9.05%.

5. The process according to claim 4, characterized in that The conditions of the defatted rice bran cyclone separation in step (2) are as follows: the rice bran flow rate is 9 kg / h, the fan frequency is 60 Hz, and the moisture content of the rice bran before the treatment is 6.18%.

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