# Optimization and Quality Analysis of Different Extraction Methods of Palm Seed Oil

Authors: Qi-Zhao Li; Zheng-Qun Cai
Journal: Complexity
 (2021)

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## Abstract

The extraction process of palm seed oil was optimized. Using palm seed as raw material, oil extraction rate was used as an index. The effects of flash extraction, ultrasonic-assisted extraction, supercritical extraction, and aqueous enzymatic extraction on the yield of palm seed oil were investigated. The extraction methods and technological conditions of palm seed oil were optimized by the orthogonal method on the basis of single factor. The seed oil was analyzed and detected. The results showed that the water enzymatic extraction method was the best, and the optimal extraction conditions were as follows: enzymatic hydrolysis time 16 h, enzymatic hydrolysis temperature 50°C, and enzymatic content 2.0%. The oil yield of palm seed was 16.48%.Conclusion. Water enzymatic extraction process of palm seed oil is reasonable, the active ingredients are rich, and the quality of seed oil is better, providing reference for the development and research of palm seed oil.


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## Body

## 1. Introduction

Palm seeds are the dried fruits of palm trees. Palms are widely planted and their mature fruits are used to dry them. The seeds are rich in active ingredients such as ursolic acid, mannitol, oleanolic acid, quercetin, oleuropein,β-sitosterol, betulin, and rhamnose. The active ingredients mainly have hemostasis, strengthen essence, nourish the liver and kidney, strengthen the body, treat blood collapse and gastroenteritis, treat eye diseases, increase the number of peripheral white blood cells, lower blood sugar, protect the liver, affect the phagocytosis of the body's reticuloendothelial system function, can improve immune function, can obviously inhibit a variety of allergic reactions, reduce body serum total cholesterol and lipid peroxide, etc. Increasing the anti-inflammatory mediator histamine causes capillary permeability and reduces the incidence of atherosclerosis. Palm seeds contain about 18 percent fat. At present, the palm is mostly used for landscaping except a few for medicinal purposes. The economic value of the palm seed is not fully utilized, and there are few reports on the extraction and separation of its seed oil. Therefore, different extraction methods, such as flash extraction, ultra-rapid extraction, ultrasonic extraction, and water enzyme extraction, were used to extract palm seed oil in this experiment in order to obtain the best extraction method and technological conditions of palm seed oil. The oil yield of different varieties was compared, and the best varieties were selected to provide reference for the comprehensive utilization and development of palm seeds.


## 2. Materials and Methods

### 2.1. Materials and Reagents

Four varieties of dry peeled palm seed fruit were purchased. Palm seeds were purchased from the Bozhou medicinal material market in Anhui Province and were identified by Professor Wei Qiang of Anhui Xinhua University. The protease, amylase, bromelain, papain, and other reagents needed for the experiment were purchased from China Reagent Company. Papain was purchased from Sinopharm Group. KOH, NaOH, petroleum ether, and so on were all analytically pure and purchased from Tianjin Best.


### 2.2. Experimental Instruments and Equipment

Supercritical extractor HA120-50-01, flash extractor JHBE-20A, gas chromatograph 7890B, Thermo Fe-260, UV-visible spectrophotometer, rotary evaporator RE-2000B, electronic balance AUW220, constant-temperature incubator LP/DHS-225, and multifunction grinder JP-800C were used.


## 2.1. Materials and Reagents

Four varieties of dry peeled palm seed fruit were purchased. Palm seeds were purchased from the Bozhou medicinal material market in Anhui Province and were identified by Professor Wei Qiang of Anhui Xinhua University. The protease, amylase, bromelain, papain, and other reagents needed for the experiment were purchased from China Reagent Company. Papain was purchased from Sinopharm Group. KOH, NaOH, petroleum ether, and so on were all analytically pure and purchased from Tianjin Best.


## 2.2. Experimental Instruments and Equipment

Supercritical extractor HA120-50-01, flash extractor JHBE-20A, gas chromatograph 7890B, Thermo Fe-260, UV-visible spectrophotometer, rotary evaporator RE-2000B, electronic balance AUW220, constant-temperature incubator LP/DHS-225, and multifunction grinder JP-800C were used.


## 3. Experimental Methods

### 3.1. Oil Flash Extraction of Palm Seed

Weigh 100 g of dried and crushed palm seed powder; add petroleum ether according to a certain ratio of solid to liquid; set flash voltage, extraction time, extraction temperature, and flash extraction; remove impurities and filter; collect the extract; decompress-rotary steam to recover the solvent; dry, weigh, and calculate the extraction rate of oil [1].


### 3.2. Supercritical Extraction of Palm Seed Oil

100 g of palm seed powder was accurately weighed into the extraction kettle; the extraction temperature, extraction time, and extraction pressure were set for supercritical extraction; CO2 fluid was separated, dried, and weighed; and the yield of palm seed oil was calculated [2].


### 3.3. Ultrasound-Assisted Extraction of Palm Seed Oil

Accurate weighing of 100 g of palm seed powder over 40 mesh into conical flask, adding appropriate amount of petroleum ether, and setting ultrasonic power, temperature, and time for ultrasonic extraction for 3–5 times are carried out. The filtrate was combined, the solvent was recovered by decompression, and the extraction rate of palm seed oil was calculated by drying and weighing [3].


### 3.4. Enzymatic Extraction of Palm Seed Oil

The palm seeds were accurately weighed and 100 g of 40 mesh powder was put into a beaker, and an appropriate amount of distilled water was added. The amount of enzyme, enzymatic hydrolysis time, and enzymatic hydrolysis temperature were set to be extracted by water enzymatic method. Enzyme elimination, extraction centrifugation, decompression recovery, drying, and weighing were performed to calculate the extraction rate of palm seed oil [4].


### 3.5. Design of Extraction Conditions for Palm Seed Oil

#### 3.5.1. Single-Factor Design of Palm Seed Oil Extraction Method

Extraction conditions for examining flash style material liquid ratio, extraction time, extraction voltage influence on palm seeds oil extraction rate, respectively, will flash type extraction single factor set to liquid ratio (1 : 10, 1 : 20, 1 : 30, 1 : 40, and 1 : 50), extraction time (30, 60, 90, 120, and 150 s), extracting voltage (75, 100, 125, 150, and 175 v), experiment of five levels, in a certain single factor when the other two factors maintain the best level. Fixed factor levels were set as the solid-liquid ratio of 1 : 30, extraction voltage of 150 V, and extraction time of 120 S [5].


#### 3.5.2. Single-Factor Design of Ultrasonic-Assisted Extraction of Palm Seed Oil

For inspection, ultrasonic temperature, ultrasonic time, and solid-liquid ratio on the palm seeds oil extraction and ultrasonic extraction, respectively, single factor is set to the material liquid ratio (1 : 10, 1 : 20, 1 :  30, and 1 : 40), ultrasonic time (20, 30, 40, 50, and 60 min), ultrasonic temperature (40, 45, 50, 55, and 60), experiment of five levels, in a certain single factor when the other two factors maintain the best level. Fixed factor levels were set as solid-liquid ratio of 1 : 30, ultrasonic power 450 W, ultrasonic temperature of 55, and extraction time of 50 min [6].


#### 3.5.3. Single-Factor Design for Supercritical Extraction of Palm Seed Oil

To study extraction temperature, extraction pressure, and extraction time on the yield of palm seed oils, respectively, extraction temperature (30, 40, 50, 60, and 70), extraction time (60, 70, 80, 90, and 100 min), extraction pressure (10, 15, 20, 25, and 30 MPa), experiment of five levels, in a certain single factor when the other two factors maintain the best level. Fixed factor levels were set as extraction temperature 50, extraction pressure 20 MPa, and extraction time 60 min [7].


#### 3.5.4. Single-Factor Design for Oil and Water Enzymatic Extraction of Palm Seed

For inspection with enzyme, enzyme solution temperature, solution time on the yield of palm seed oils, respectively, with enzyme amount (0.50, 1.00, 1.50, 2.00, and 2.50%), enzymolysis time (8, 12, 16, 20, and 24), temperature, and enzyme solution (35, 40, 45, 50, and 55), experiment of five levels, in a certain single factor when the other two factors maintain the best level. The fixed factor levels were set as 1.00% enzymatic dosage, 50 enzymatic hydrolysis temperature, and 16 h enzymatic hydrolysis time [8].


#### 3.5.5. Design Orthogonal Test

On the basis of the above single-factor experiments, orthogonal experiments were used to optimize the extraction conditions of palm seed oil with the extraction rate of palm seed oil as the index. [9].


### 3.6. Oil Composition Analysis of Palm Seeds

The palm seed oil sample was accurately transferred into a 1.0 mL flask, and 5% KOH-methanol solution was added in 2.0 ml 40°C water bath for 15 min. Then, the sample was cooled at room temperature and dissolved in 2.0 mln-hexane and moved to a 10 mL volumetric flask for constant volume. After standing for 1 d, the organic phase was absorbed and filtered with a 0.45 um filter membrane for standby detection [10].


## 3.1. Oil Flash Extraction of Palm Seed

Weigh 100 g of dried and crushed palm seed powder; add petroleum ether according to a certain ratio of solid to liquid; set flash voltage, extraction time, extraction temperature, and flash extraction; remove impurities and filter; collect the extract; decompress-rotary steam to recover the solvent; dry, weigh, and calculate the extraction rate of oil [1].


## 3.2. Supercritical Extraction of Palm Seed Oil

100 g of palm seed powder was accurately weighed into the extraction kettle; the extraction temperature, extraction time, and extraction pressure were set for supercritical extraction; CO2 fluid was separated, dried, and weighed; and the yield of palm seed oil was calculated [2].


## 3.3. Ultrasound-Assisted Extraction of Palm Seed Oil

Accurate weighing of 100 g of palm seed powder over 40 mesh into conical flask, adding appropriate amount of petroleum ether, and setting ultrasonic power, temperature, and time for ultrasonic extraction for 3–5 times are carried out. The filtrate was combined, the solvent was recovered by decompression, and the extraction rate of palm seed oil was calculated by drying and weighing [3].


## 3.4. Enzymatic Extraction of Palm Seed Oil

The palm seeds were accurately weighed and 100 g of 40 mesh powder was put into a beaker, and an appropriate amount of distilled water was added. The amount of enzyme, enzymatic hydrolysis time, and enzymatic hydrolysis temperature were set to be extracted by water enzymatic method. Enzyme elimination, extraction centrifugation, decompression recovery, drying, and weighing were performed to calculate the extraction rate of palm seed oil [4].


## 3.5. Design of Extraction Conditions for Palm Seed Oil

### 3.5.1. Single-Factor Design of Palm Seed Oil Extraction Method

Extraction conditions for examining flash style material liquid ratio, extraction time, extraction voltage influence on palm seeds oil extraction rate, respectively, will flash type extraction single factor set to liquid ratio (1 : 10, 1 : 20, 1 : 30, 1 : 40, and 1 : 50), extraction time (30, 60, 90, 120, and 150 s), extracting voltage (75, 100, 125, 150, and 175 v), experiment of five levels, in a certain single factor when the other two factors maintain the best level. Fixed factor levels were set as the solid-liquid ratio of 1 : 30, extraction voltage of 150 V, and extraction time of 120 S [5].


### 3.5.2. Single-Factor Design of Ultrasonic-Assisted Extraction of Palm Seed Oil

For inspection, ultrasonic temperature, ultrasonic time, and solid-liquid ratio on the palm seeds oil extraction and ultrasonic extraction, respectively, single factor is set to the material liquid ratio (1 : 10, 1 : 20, 1 :  30, and 1 : 40), ultrasonic time (20, 30, 40, 50, and 60 min), ultrasonic temperature (40, 45, 50, 55, and 60), experiment of five levels, in a certain single factor when the other two factors maintain the best level. Fixed factor levels were set as solid-liquid ratio of 1 : 30, ultrasonic power 450 W, ultrasonic temperature of 55, and extraction time of 50 min [6].


### 3.5.3. Single-Factor Design for Supercritical Extraction of Palm Seed Oil

To study extraction temperature, extraction pressure, and extraction time on the yield of palm seed oils, respectively, extraction temperature (30, 40, 50, 60, and 70), extraction time (60, 70, 80, 90, and 100 min), extraction pressure (10, 15, 20, 25, and 30 MPa), experiment of five levels, in a certain single factor when the other two factors maintain the best level. Fixed factor levels were set as extraction temperature 50, extraction pressure 20 MPa, and extraction time 60 min [7].


### 3.5.4. Single-Factor Design for Oil and Water Enzymatic Extraction of Palm Seed

For inspection with enzyme, enzyme solution temperature, solution time on the yield of palm seed oils, respectively, with enzyme amount (0.50, 1.00, 1.50, 2.00, and 2.50%), enzymolysis time (8, 12, 16, 20, and 24), temperature, and enzyme solution (35, 40, 45, 50, and 55), experiment of five levels, in a certain single factor when the other two factors maintain the best level. The fixed factor levels were set as 1.00% enzymatic dosage, 50 enzymatic hydrolysis temperature, and 16 h enzymatic hydrolysis time [8].


### 3.5.5. Design Orthogonal Test

On the basis of the above single-factor experiments, orthogonal experiments were used to optimize the extraction conditions of palm seed oil with the extraction rate of palm seed oil as the index. [9].


## 3.5.1. Single-Factor Design of Palm Seed Oil Extraction Method

Extraction conditions for examining flash style material liquid ratio, extraction time, extraction voltage influence on palm seeds oil extraction rate, respectively, will flash type extraction single factor set to liquid ratio (1 : 10, 1 : 20, 1 : 30, 1 : 40, and 1 : 50), extraction time (30, 60, 90, 120, and 150 s), extracting voltage (75, 100, 125, 150, and 175 v), experiment of five levels, in a certain single factor when the other two factors maintain the best level. Fixed factor levels were set as the solid-liquid ratio of 1 : 30, extraction voltage of 150 V, and extraction time of 120 S [5].


## 3.5.2. Single-Factor Design of Ultrasonic-Assisted Extraction of Palm Seed Oil

For inspection, ultrasonic temperature, ultrasonic time, and solid-liquid ratio on the palm seeds oil extraction and ultrasonic extraction, respectively, single factor is set to the material liquid ratio (1 : 10, 1 : 20, 1 :  30, and 1 : 40), ultrasonic time (20, 30, 40, 50, and 60 min), ultrasonic temperature (40, 45, 50, 55, and 60), experiment of five levels, in a certain single factor when the other two factors maintain the best level. Fixed factor levels were set as solid-liquid ratio of 1 : 30, ultrasonic power 450 W, ultrasonic temperature of 55, and extraction time of 50 min [6].


## 3.5.3. Single-Factor Design for Supercritical Extraction of Palm Seed Oil

To study extraction temperature, extraction pressure, and extraction time on the yield of palm seed oils, respectively, extraction temperature (30, 40, 50, 60, and 70), extraction time (60, 70, 80, 90, and 100 min), extraction pressure (10, 15, 20, 25, and 30 MPa), experiment of five levels, in a certain single factor when the other two factors maintain the best level. Fixed factor levels were set as extraction temperature 50, extraction pressure 20 MPa, and extraction time 60 min [7].


## 3.5.4. Single-Factor Design for Oil and Water Enzymatic Extraction of Palm Seed

For inspection with enzyme, enzyme solution temperature, solution time on the yield of palm seed oils, respectively, with enzyme amount (0.50, 1.00, 1.50, 2.00, and 2.50%), enzymolysis time (8, 12, 16, 20, and 24), temperature, and enzyme solution (35, 40, 45, 50, and 55), experiment of five levels, in a certain single factor when the other two factors maintain the best level. The fixed factor levels were set as 1.00% enzymatic dosage, 50 enzymatic hydrolysis temperature, and 16 h enzymatic hydrolysis time [8].


## 3.5.5. Design Orthogonal Test

On the basis of the above single-factor experiments, orthogonal experiments were used to optimize the extraction conditions of palm seed oil with the extraction rate of palm seed oil as the index. [9].


## 3.6. Oil Composition Analysis of Palm Seeds

The palm seed oil sample was accurately transferred into a 1.0 mL flask, and 5% KOH-methanol solution was added in 2.0 ml 40°C water bath for 15 min. Then, the sample was cooled at room temperature and dissolved in 2.0 mln-hexane and moved to a 10 mL volumetric flask for constant volume. After standing for 1 d, the organic phase was absorbed and filtered with a 0.45 um filter membrane for standby detection [10].


## 4. Results and Discussion

### 4.1. Single-Factor Experiment on Extraction Rate of Palm Seed Oil

#### 4.1.1. Investigation of Single-Factor Experiment of Flash Extraction of Palm Seed Oil (See Figure1)

Figure1 shows that the solid-liquid ratio, extraction voltage, and extraction time have significant effects on the oil yield of palm seed. As palm seeds and solid-liquid ratio, flash extraction voltage, extraction time increase, the oil extraction rate rises gradually, in the ratio of material liquid: 1 : 30, extracting time 120 s, extraction voltage 150 v to extract the oil yield declined slightly after 120 s, considering flash type palm seed oil extraction experiments choice for the extraction of material liquid than 1 : 30, extraction time 120 s, voltage 150 v, experiment in next step [11].Figure 1
Influence of different factors on extraction rate of palm seed oil by the flash extraction method.


#### 4.1.2. Single-Factor Study of Ultrasound-Assisted Extraction of Palm Seed Oil (See Figure2)

It can be seen from Figure2 that ultrasonic time, ultrasonic temperature, and solid-liquid ratio had significant effects on the oil yield of palm seed. With the increase of ultrasonic time [12], solid-liquid ratio, and ultrasonic temperature, the oil yield of palm seed increased significantly. However, after the solid-liquid ratio of 1 : 25, ultrasonic temperature of 50°C, and ultrasonic time of 50 min, the extraction yield of oil was slightly decreased. Considering the overall solid-liquid ratio of 1 : 30, ultrasonic time of 40 min, ultrasonic power/W, and ultrasonic temperature of 55, the ultrasonic assisted extraction experiment of palm seed oil was selected as the basis for the later experiment [13].Figure 2
Influence of different factors on the yield of palm seed oil by ultrasound-assisted flash extraction.


#### 4.1.3. Single-Factor Study of Supercritical Extraction Experiment of Palm Seed Oil (See Figure3)

It can be seen from Figure3 that extraction temperature, extraction pressure, and extraction time have significant effects on the oil yield of palm seed. With the increase of extraction temperature, extraction pressure, and extraction time, the oil yield of palm seed increases significantly. However, the oil yield decreased slightly after extraction temperature 50°C, extraction time 90 min, and extraction pressure 20 MPa. Considering the supercritical extraction experiment of palm seed oil, the extraction temperature 50°C, extraction time 90 min, and extraction pressure 20 MPa were selected as the basis of the later experiment [14].Figure 3
Influence of different factors on oil yield of palm seed by supercritical extraction.


#### 4.1.4. Single-Factor Study of Oil-Water Enzymatic Extraction of Palm Seed (See Figure4)

It can be seen from Figure4 that the amount of enzyme added, the temperature of enzymatic hydrolysis and the time of enzymatic hydrolysis have significant effects on the yield of palm seed oil. With the increase of the amount of compound enzyme added, the temperature of enzymatic hydrolysis, and the time of enzymatic hydrolysis, the yield of palm seed oil increases significantly. However, the yield of oil was slightly decreased after the addition of 1.0% enzyme amount, 16 h enzymatic hydrolysis time, and 50°C enzymatic hydrolysis temperature. Considering the overall selection of palm seed oil-water enzymatic extraction experiment, 0.20% enzyme amount, 50°C enzymatic hydrolysis temperature, and 20 h enzymatic hydrolysis time were selected as the basis of the later experiment [15].Figure 4
Influence of different factors on oil yield of palm seed by hydroenzymatic extraction.


### 4.2. Orthogonal Experiment on Extraction of Palm Seed Oil

#### 4.2.1. Orthogonal Experiment of Oil Scintillation Extraction of Palm Seed

For the orthogonal experiment of flash extraction of palm seed oil, the factor levels are shown in Table1, and the orthogonal experiment is shown in Table 2.Table 1
Factor levels of the flash extraction method.
Horizontal solid-liquidRatio of 1 : 10Extraction time (s)Extraction voltage (v)1160100229015033120200Table 2
Orthogonal experimental design and results of oil flash extraction from palm seed.
No.ABCOil yield (%)111111.48212215.65313320.86421213.58522316.24623117.45731315.85832116.26933216.44K147.9940.9145.19K247.2748.1545.67K348.5554.7552.95R1.2813.847.76It can be seen from Table2 that in the flash extraction experiment of palm seed oil, extraction time, extraction voltage, and solid-liquid ratio all had influences on the oil yield obtained from the extraction. Because B > C > A, it can be seen that the extraction time is greater than the extraction voltage is greater, and the influence is greater than the solid-liquid ratio. The extraction voltage had the greatest influence, and the optimal extraction conditions were as follows: A3B3C3, extraction time of 120 S, namely, extraction voltage of 150 V, solid-liquid ratio of 1 : 30 [16].


#### 4.2.2. Orthogonal Experiment of Ultrasonic-Assisted Extraction of Palm Seed Oil

The orthogonal experiment of ultrasound-assisted extraction of palm seed oil and the factor levels are shown in Table3 and the orthogonal experiment in Table 4.Table 3
Factor levels of the ultrasound-assisted extraction method.
Horizontal ultrasonicUltrasonic time (min)Temperature (°C)Ultrasonic power (V)140454002505045036055500Table 4
Orthogonal experimental design and results of ultrasonic-assisted extraction of palm seed oil.
No.ABCOil yield (%)111113.38212218.00313314.50421215.25522315.20623113.25731314.55832113.08933214.85K143.8843.1839.71K245.7848.0548.10K342.3842.6044.25R3.405.458.39As can be seen from Table4, ultrasonic time, ultrasonic power, and temperature ultrasonic all had influences on the extraction yield of palm seed oil in the ultrasound-assisted extraction experiment, because C > B > A showed that the influence of ultrasonic power on the extraction yield of palm seed oil was greater than that of ultrasonic time and temperature. Ultrasonic power had the greatest effect, and the optimal extraction conditions were as follows: A2B2C2, namely, ultrasonic temperature 45°C, ultrasonic power 450 V, and ultrasonic time 50 min [17].


#### 4.2.3. Orthogonal Experiment of Supercritical Extraction of Palm Seed Oil

The orthogonal experiment of supercritical extraction of palm seed oil and the factor levels are shown in Table5, and the orthogonal experiment is shown in Table 6.Table 5
Factor levels of supercritical extraction method.
HorizontalExtraction temperature (°C)Extraction pressure (MPa)Extraction time (min)145153025020603552590Table 6
Orthogonal design and results of supercritical extraction of palm seed oil.
No.ABCOil yield (%)111112.25212218.30313314.55421217.25522317.85623114.58731313.80832115.75933214.48K146.1044.3043.58K249.6851.9050.03K344.0343.6146.20R5.658.296.45It can be seen from Table6 that, under the supercritical extraction experiment of palm seed oil, the extraction temperature, extraction time, and extraction pressure all had influences on the extraction rate of palm seed oil. Because of B > C > A, the extraction pressure was greater than the extraction time was greater than the extraction temperature, among which the extraction pressure had the greatest influence. The optimal extraction conditions were as follows: A2B2C2, extraction pressure 20 MPa, extraction temperature 50°C, and extraction time 60 min [18].


#### 4.2.4. Orthogonal Experiment of Oil and Water Extraction of Palm Seed

The orthogonal experiment of water enzymatic extraction of palm seed oil and the factor levels are shown in Table7, and the orthogonal experiment is shown in Table 8.Table 7
Factor levels of the water enzymatic extraction method.
HorizontalEnzymatic hydrolysis temperature (h)With enzyme quantity (%)Enzymatic hydrolysis (°C)18150216255324360Table 8
Orthogonal experimental design and results of supercritical extraction of palm seed oil.
No.ABCOil yield (%)111117.55212215.28313314.82421216.56522315.74623116.68731317.26832113.92933216.08K147.6544.9448.15K248.9851.3947.92K347.2647.5847.82R1.726.430.33It can be seen from Table8 that, in the water enzymatic extraction experiment of palm seed oil, the enzymatic hydrolysis time, the enzymatic hydrolysis temperature, and the amount of enzymes added all have influences on the oil yield obtained. Because of B > A > C, it can be seen that the enzymatic hydrolysis temperature is greater than the amount of enzymes added, among which the enzymatic hydrolysis temperature has the greatest influence. The optimal extraction conditions of palm seed oil were as follows: A2B2C1, enzymatic hydrolysis time 16 h, enzymatic hydrolysis temperature 50°C, and enzymatic content 2.0% [19].


### 4.3. Verification Experiment

The experimental verification results of the optimal combination of the above four palm seed oil extraction methods are shown in Table9.Table 9
Comparison of the best results of 4 extraction methods of palm seed oil.
Extraction methodOil yield (%)Flash extraction10.26Ultrasonic assisted extraction15.28Supercritical extraction14.16Water enzymatic assisted extraction16.29As can be seen from Table9, among the four extraction methods of palm seed oil, the oil yield of aqueous enzyme-assisted extraction was the highest, and the best extraction method of palm seed oil was selected after comprehensive consideration [20].


### 4.4. Comparison of Extraction Rates of Oil from Different Varieties of Palm Seeds

The oil yield of oil extracted from 4 different varieties of palm seeds was compared and analyzed by enzymatic hydrolysis. The results are shown in Table10.Table 10
Comparison of oil yield results of different varieties of palm seed under optimal technological conditions.
VarietiesOil yield (%)Spell brown11.44Mountain brown10.22Fan palm16.37Dickinson brown10.58As can be seen from Table10, among the four palm varieties, under the same water enzymatic extraction conditions and the same technology, the palm fan with the highest seed oil yield was considered to be the most suitable variety for oil extraction of palm fan [21].


### 4.5. Physical and Chemical Indexes of Palm Seed Grease

Under the optimal extraction conditions, the oil of palm seed was extracted by enzymatic method and its physical and chemical indexes were determined. The results are shown in Table11.Table 11
Physical and chemical properties of palm seed oil.
ProjectIndicatorsAcid value (KOH)/(mg/g)3.22Peroxide value (mmol/kg)7.3Saponification value (KOH)/(mg/g)197Iodine value (I)/(g/100 g)126Nonsaponification material (%)1.37Transparency (20°C, 24 h)ClearSmellLight yellow oilyAs can be seen from Table11, palm seed oleic acid value, KOH of 3.28 mg/g is relatively low, and free fatty acid content is relatively low. The peroxide value of 7.3 mmol/kg was higher, which was easy to oxidize and deteriorate. The saponification value, KOH of 197 mg/g, is basically in line with the requirement of saponification value of edible oil [22].


### 4.6. Fatty Acid Composition of Palm Seed Oil

Commodity oil was used as reference GB/T17376-2008 for sample pretreatment, and GC-MS was used for determination and analysis according to Sun Hong's method. The results are shown in Table12.Table 12
Fatty acid composition and content (%) of palm seed oil.
Fatty acidsPalm seed oilProduct oilPalmitic acid (C16 : 0)8.096.66Nutmeg acid (C14 : 0)0.550.47Stearic acid (C18 : 0)3.663.27Oleic acid (C18 : 1)18.4521.17Linolenic acid (C18 : 3)24.2225.36Linoleic acid (C18 : 2)42.3643.29Peanut acid (C20 : 0)0.780.64Arachidonic acid (C20 : 1)0.480.34Oleic acid0.260.17It can be seen from Table12 that the fatty acid composition of palm seed oil is similar to that of olive oil, and the palm seed oil contains relatively low saturated fatty acid accounting for about 13.84%. They were mainly palmitic acid and stearic acid. The contents of unsaturated fatty acids were 83.23%, mainly linoleic acid, linolenic acid, and oleic acid [23].


## 4.1. Single-Factor Experiment on Extraction Rate of Palm Seed Oil

### 4.1.1. Investigation of Single-Factor Experiment of Flash Extraction of Palm Seed Oil (See Figure1)

Figure1 shows that the solid-liquid ratio, extraction voltage, and extraction time have significant effects on the oil yield of palm seed. As palm seeds and solid-liquid ratio, flash extraction voltage, extraction time increase, the oil extraction rate rises gradually, in the ratio of material liquid: 1 : 30, extracting time 120 s, extraction voltage 150 v to extract the oil yield declined slightly after 120 s, considering flash type palm seed oil extraction experiments choice for the extraction of material liquid than 1 : 30, extraction time 120 s, voltage 150 v, experiment in next step [11].Figure 1
Influence of different factors on extraction rate of palm seed oil by the flash extraction method.


### 4.1.2. Single-Factor Study of Ultrasound-Assisted Extraction of Palm Seed Oil (See Figure2)

It can be seen from Figure2 that ultrasonic time, ultrasonic temperature, and solid-liquid ratio had significant effects on the oil yield of palm seed. With the increase of ultrasonic time [12], solid-liquid ratio, and ultrasonic temperature, the oil yield of palm seed increased significantly. However, after the solid-liquid ratio of 1 : 25, ultrasonic temperature of 50°C, and ultrasonic time of 50 min, the extraction yield of oil was slightly decreased. Considering the overall solid-liquid ratio of 1 : 30, ultrasonic time of 40 min, ultrasonic power/W, and ultrasonic temperature of 55, the ultrasonic assisted extraction experiment of palm seed oil was selected as the basis for the later experiment [13].Figure 2
Influence of different factors on the yield of palm seed oil by ultrasound-assisted flash extraction.


### 4.1.3. Single-Factor Study of Supercritical Extraction Experiment of Palm Seed Oil (See Figure3)

It can be seen from Figure3 that extraction temperature, extraction pressure, and extraction time have significant effects on the oil yield of palm seed. With the increase of extraction temperature, extraction pressure, and extraction time, the oil yield of palm seed increases significantly. However, the oil yield decreased slightly after extraction temperature 50°C, extraction time 90 min, and extraction pressure 20 MPa. Considering the supercritical extraction experiment of palm seed oil, the extraction temperature 50°C, extraction time 90 min, and extraction pressure 20 MPa were selected as the basis of the later experiment [14].Figure 3
Influence of different factors on oil yield of palm seed by supercritical extraction.


### 4.1.4. Single-Factor Study of Oil-Water Enzymatic Extraction of Palm Seed (See Figure4)

It can be seen from Figure4 that the amount of enzyme added, the temperature of enzymatic hydrolysis and the time of enzymatic hydrolysis have significant effects on the yield of palm seed oil. With the increase of the amount of compound enzyme added, the temperature of enzymatic hydrolysis, and the time of enzymatic hydrolysis, the yield of palm seed oil increases significantly. However, the yield of oil was slightly decreased after the addition of 1.0% enzyme amount, 16 h enzymatic hydrolysis time, and 50°C enzymatic hydrolysis temperature. Considering the overall selection of palm seed oil-water enzymatic extraction experiment, 0.20% enzyme amount, 50°C enzymatic hydrolysis temperature, and 20 h enzymatic hydrolysis time were selected as the basis of the later experiment [15].Figure 4
Influence of different factors on oil yield of palm seed by hydroenzymatic extraction.


## 4.1.1. Investigation of Single-Factor Experiment of Flash Extraction of Palm Seed Oil (See Figure1)

Figure1 shows that the solid-liquid ratio, extraction voltage, and extraction time have significant effects on the oil yield of palm seed. As palm seeds and solid-liquid ratio, flash extraction voltage, extraction time increase, the oil extraction rate rises gradually, in the ratio of material liquid: 1 : 30, extracting time 120 s, extraction voltage 150 v to extract the oil yield declined slightly after 120 s, considering flash type palm seed oil extraction experiments choice for the extraction of material liquid than 1 : 30, extraction time 120 s, voltage 150 v, experiment in next step [11].Figure 1
Influence of different factors on extraction rate of palm seed oil by the flash extraction method.


## 4.1.2. Single-Factor Study of Ultrasound-Assisted Extraction of Palm Seed Oil (See Figure2)

It can be seen from Figure2 that ultrasonic time, ultrasonic temperature, and solid-liquid ratio had significant effects on the oil yield of palm seed. With the increase of ultrasonic time [12], solid-liquid ratio, and ultrasonic temperature, the oil yield of palm seed increased significantly. However, after the solid-liquid ratio of 1 : 25, ultrasonic temperature of 50°C, and ultrasonic time of 50 min, the extraction yield of oil was slightly decreased. Considering the overall solid-liquid ratio of 1 : 30, ultrasonic time of 40 min, ultrasonic power/W, and ultrasonic temperature of 55, the ultrasonic assisted extraction experiment of palm seed oil was selected as the basis for the later experiment [13].Figure 2
Influence of different factors on the yield of palm seed oil by ultrasound-assisted flash extraction.


## 4.1.3. Single-Factor Study of Supercritical Extraction Experiment of Palm Seed Oil (See Figure3)

It can be seen from Figure3 that extraction temperature, extraction pressure, and extraction time have significant effects on the oil yield of palm seed. With the increase of extraction temperature, extraction pressure, and extraction time, the oil yield of palm seed increases significantly. However, the oil yield decreased slightly after extraction temperature 50°C, extraction time 90 min, and extraction pressure 20 MPa. Considering the supercritical extraction experiment of palm seed oil, the extraction temperature 50°C, extraction time 90 min, and extraction pressure 20 MPa were selected as the basis of the later experiment [14].Figure 3
Influence of different factors on oil yield of palm seed by supercritical extraction.


## 4.1.4. Single-Factor Study of Oil-Water Enzymatic Extraction of Palm Seed (See Figure4)

It can be seen from Figure4 that the amount of enzyme added, the temperature of enzymatic hydrolysis and the time of enzymatic hydrolysis have significant effects on the yield of palm seed oil. With the increase of the amount of compound enzyme added, the temperature of enzymatic hydrolysis, and the time of enzymatic hydrolysis, the yield of palm seed oil increases significantly. However, the yield of oil was slightly decreased after the addition of 1.0% enzyme amount, 16 h enzymatic hydrolysis time, and 50°C enzymatic hydrolysis temperature. Considering the overall selection of palm seed oil-water enzymatic extraction experiment, 0.20% enzyme amount, 50°C enzymatic hydrolysis temperature, and 20 h enzymatic hydrolysis time were selected as the basis of the later experiment [15].Figure 4
Influence of different factors on oil yield of palm seed by hydroenzymatic extraction.


## 4.2. Orthogonal Experiment on Extraction of Palm Seed Oil

### 4.2.1. Orthogonal Experiment of Oil Scintillation Extraction of Palm Seed

For the orthogonal experiment of flash extraction of palm seed oil, the factor levels are shown in Table1, and the orthogonal experiment is shown in Table 2.Table 1
Factor levels of the flash extraction method.
Horizontal solid-liquidRatio of 1 : 10Extraction time (s)Extraction voltage (v)1160100229015033120200Table 2
Orthogonal experimental design and results of oil flash extraction from palm seed.
No.ABCOil yield (%)111111.48212215.65313320.86421213.58522316.24623117.45731315.85832116.26933216.44K147.9940.9145.19K247.2748.1545.67K348.5554.7552.95R1.2813.847.76It can be seen from Table2 that in the flash extraction experiment of palm seed oil, extraction time, extraction voltage, and solid-liquid ratio all had influences on the oil yield obtained from the extraction. Because B > C > A, it can be seen that the extraction time is greater than the extraction voltage is greater, and the influence is greater than the solid-liquid ratio. The extraction voltage had the greatest influence, and the optimal extraction conditions were as follows: A3B3C3, extraction time of 120 S, namely, extraction voltage of 150 V, solid-liquid ratio of 1 : 30 [16].


### 4.2.2. Orthogonal Experiment of Ultrasonic-Assisted Extraction of Palm Seed Oil

The orthogonal experiment of ultrasound-assisted extraction of palm seed oil and the factor levels are shown in Table3 and the orthogonal experiment in Table 4.Table 3
Factor levels of the ultrasound-assisted extraction method.
Horizontal ultrasonicUltrasonic time (min)Temperature (°C)Ultrasonic power (V)140454002505045036055500Table 4
Orthogonal experimental design and results of ultrasonic-assisted extraction of palm seed oil.
No.ABCOil yield (%)111113.38212218.00313314.50421215.25522315.20623113.25731314.55832113.08933214.85K143.8843.1839.71K245.7848.0548.10K342.3842.6044.25R3.405.458.39As can be seen from Table4, ultrasonic time, ultrasonic power, and temperature ultrasonic all had influences on the extraction yield of palm seed oil in the ultrasound-assisted extraction experiment, because C > B > A showed that the influence of ultrasonic power on the extraction yield of palm seed oil was greater than that of ultrasonic time and temperature. Ultrasonic power had the greatest effect, and the optimal extraction conditions were as follows: A2B2C2, namely, ultrasonic temperature 45°C, ultrasonic power 450 V, and ultrasonic time 50 min [17].


### 4.2.3. Orthogonal Experiment of Supercritical Extraction of Palm Seed Oil

The orthogonal experiment of supercritical extraction of palm seed oil and the factor levels are shown in Table5, and the orthogonal experiment is shown in Table 6.Table 5
Factor levels of supercritical extraction method.
HorizontalExtraction temperature (°C)Extraction pressure (MPa)Extraction time (min)145153025020603552590Table 6
Orthogonal design and results of supercritical extraction of palm seed oil.
No.ABCOil yield (%)111112.25212218.30313314.55421217.25522317.85623114.58731313.80832115.75933214.48K146.1044.3043.58K249.6851.9050.03K344.0343.6146.20R5.658.296.45It can be seen from Table6 that, under the supercritical extraction experiment of palm seed oil, the extraction temperature, extraction time, and extraction pressure all had influences on the extraction rate of palm seed oil. Because of B > C > A, the extraction pressure was greater than the extraction time was greater than the extraction temperature, among which the extraction pressure had the greatest influence. The optimal extraction conditions were as follows: A2B2C2, extraction pressure 20 MPa, extraction temperature 50°C, and extraction time 60 min [18].


### 4.2.4. Orthogonal Experiment of Oil and Water Extraction of Palm Seed

The orthogonal experiment of water enzymatic extraction of palm seed oil and the factor levels are shown in Table7, and the orthogonal experiment is shown in Table 8.Table 7
Factor levels of the water enzymatic extraction method.
HorizontalEnzymatic hydrolysis temperature (h)With enzyme quantity (%)Enzymatic hydrolysis (°C)18150216255324360Table 8
Orthogonal experimental design and results of supercritical extraction of palm seed oil.
No.ABCOil yield (%)111117.55212215.28313314.82421216.56522315.74623116.68731317.26832113.92933216.08K147.6544.9448.15K248.9851.3947.92K347.2647.5847.82R1.726.430.33It can be seen from Table8 that, in the water enzymatic extraction experiment of palm seed oil, the enzymatic hydrolysis time, the enzymatic hydrolysis temperature, and the amount of enzymes added all have influences on the oil yield obtained. Because of B > A > C, it can be seen that the enzymatic hydrolysis temperature is greater than the amount of enzymes added, among which the enzymatic hydrolysis temperature has the greatest influence. The optimal extraction conditions of palm seed oil were as follows: A2B2C1, enzymatic hydrolysis time 16 h, enzymatic hydrolysis temperature 50°C, and enzymatic content 2.0% [19].


## 4.2.1. Orthogonal Experiment of Oil Scintillation Extraction of Palm Seed

For the orthogonal experiment of flash extraction of palm seed oil, the factor levels are shown in Table1, and the orthogonal experiment is shown in Table 2.Table 1
Factor levels of the flash extraction method.
Horizontal solid-liquidRatio of 1 : 10Extraction time (s)Extraction voltage (v)1160100229015033120200Table 2
Orthogonal experimental design and results of oil flash extraction from palm seed.
No.ABCOil yield (%)111111.48212215.65313320.86421213.58522316.24623117.45731315.85832116.26933216.44K147.9940.9145.19K247.2748.1545.67K348.5554.7552.95R1.2813.847.76It can be seen from Table2 that in the flash extraction experiment of palm seed oil, extraction time, extraction voltage, and solid-liquid ratio all had influences on the oil yield obtained from the extraction. Because B > C > A, it can be seen that the extraction time is greater than the extraction voltage is greater, and the influence is greater than the solid-liquid ratio. The extraction voltage had the greatest influence, and the optimal extraction conditions were as follows: A3B3C3, extraction time of 120 S, namely, extraction voltage of 150 V, solid-liquid ratio of 1 : 30 [16].


## 4.2.2. Orthogonal Experiment of Ultrasonic-Assisted Extraction of Palm Seed Oil

The orthogonal experiment of ultrasound-assisted extraction of palm seed oil and the factor levels are shown in Table3 and the orthogonal experiment in Table 4.Table 3
Factor levels of the ultrasound-assisted extraction method.
Horizontal ultrasonicUltrasonic time (min)Temperature (°C)Ultrasonic power (V)140454002505045036055500Table 4
Orthogonal experimental design and results of ultrasonic-assisted extraction of palm seed oil.
No.ABCOil yield (%)111113.38212218.00313314.50421215.25522315.20623113.25731314.55832113.08933214.85K143.8843.1839.71K245.7848.0548.10K342.3842.6044.25R3.405.458.39As can be seen from Table4, ultrasonic time, ultrasonic power, and temperature ultrasonic all had influences on the extraction yield of palm seed oil in the ultrasound-assisted extraction experiment, because C > B > A showed that the influence of ultrasonic power on the extraction yield of palm seed oil was greater than that of ultrasonic time and temperature. Ultrasonic power had the greatest effect, and the optimal extraction conditions were as follows: A2B2C2, namely, ultrasonic temperature 45°C, ultrasonic power 450 V, and ultrasonic time 50 min [17].


## 4.2.3. Orthogonal Experiment of Supercritical Extraction of Palm Seed Oil

The orthogonal experiment of supercritical extraction of palm seed oil and the factor levels are shown in Table5, and the orthogonal experiment is shown in Table 6.Table 5
Factor levels of supercritical extraction method.
HorizontalExtraction temperature (°C)Extraction pressure (MPa)Extraction time (min)145153025020603552590Table 6
Orthogonal design and results of supercritical extraction of palm seed oil.
No.ABCOil yield (%)111112.25212218.30313314.55421217.25522317.85623114.58731313.80832115.75933214.48K146.1044.3043.58K249.6851.9050.03K344.0343.6146.20R5.658.296.45It can be seen from Table6 that, under the supercritical extraction experiment of palm seed oil, the extraction temperature, extraction time, and extraction pressure all had influences on the extraction rate of palm seed oil. Because of B > C > A, the extraction pressure was greater than the extraction time was greater than the extraction temperature, among which the extraction pressure had the greatest influence. The optimal extraction conditions were as follows: A2B2C2, extraction pressure 20 MPa, extraction temperature 50°C, and extraction time 60 min [18].


## 4.2.4. Orthogonal Experiment of Oil and Water Extraction of Palm Seed

The orthogonal experiment of water enzymatic extraction of palm seed oil and the factor levels are shown in Table7, and the orthogonal experiment is shown in Table 8.Table 7
Factor levels of the water enzymatic extraction method.
HorizontalEnzymatic hydrolysis temperature (h)With enzyme quantity (%)Enzymatic hydrolysis (°C)18150216255324360Table 8
Orthogonal experimental design and results of supercritical extraction of palm seed oil.
No.ABCOil yield (%)111117.55212215.28313314.82421216.56522315.74623116.68731317.26832113.92933216.08K147.6544.9448.15K248.9851.3947.92K347.2647.5847.82R1.726.430.33It can be seen from Table8 that, in the water enzymatic extraction experiment of palm seed oil, the enzymatic hydrolysis time, the enzymatic hydrolysis temperature, and the amount of enzymes added all have influences on the oil yield obtained. Because of B > A > C, it can be seen that the enzymatic hydrolysis temperature is greater than the amount of enzymes added, among which the enzymatic hydrolysis temperature has the greatest influence. The optimal extraction conditions of palm seed oil were as follows: A2B2C1, enzymatic hydrolysis time 16 h, enzymatic hydrolysis temperature 50°C, and enzymatic content 2.0% [19].


## 4.3. Verification Experiment

The experimental verification results of the optimal combination of the above four palm seed oil extraction methods are shown in Table9.Table 9
Comparison of the best results of 4 extraction methods of palm seed oil.
Extraction methodOil yield (%)Flash extraction10.26Ultrasonic assisted extraction15.28Supercritical extraction14.16Water enzymatic assisted extraction16.29As can be seen from Table9, among the four extraction methods of palm seed oil, the oil yield of aqueous enzyme-assisted extraction was the highest, and the best extraction method of palm seed oil was selected after comprehensive consideration [20].


## 4.4. Comparison of Extraction Rates of Oil from Different Varieties of Palm Seeds

The oil yield of oil extracted from 4 different varieties of palm seeds was compared and analyzed by enzymatic hydrolysis. The results are shown in Table10.Table 10
Comparison of oil yield results of different varieties of palm seed under optimal technological conditions.
VarietiesOil yield (%)Spell brown11.44Mountain brown10.22Fan palm16.37Dickinson brown10.58As can be seen from Table10, among the four palm varieties, under the same water enzymatic extraction conditions and the same technology, the palm fan with the highest seed oil yield was considered to be the most suitable variety for oil extraction of palm fan [21].


## 4.5. Physical and Chemical Indexes of Palm Seed Grease

Under the optimal extraction conditions, the oil of palm seed was extracted by enzymatic method and its physical and chemical indexes were determined. The results are shown in Table11.Table 11
Physical and chemical properties of palm seed oil.
ProjectIndicatorsAcid value (KOH)/(mg/g)3.22Peroxide value (mmol/kg)7.3Saponification value (KOH)/(mg/g)197Iodine value (I)/(g/100 g)126Nonsaponification material (%)1.37Transparency (20°C, 24 h)ClearSmellLight yellow oilyAs can be seen from Table11, palm seed oleic acid value, KOH of 3.28 mg/g is relatively low, and free fatty acid content is relatively low. The peroxide value of 7.3 mmol/kg was higher, which was easy to oxidize and deteriorate. The saponification value, KOH of 197 mg/g, is basically in line with the requirement of saponification value of edible oil [22].


## 4.6. Fatty Acid Composition of Palm Seed Oil

Commodity oil was used as reference GB/T17376-2008 for sample pretreatment, and GC-MS was used for determination and analysis according to Sun Hong's method. The results are shown in Table12.Table 12
Fatty acid composition and content (%) of palm seed oil.
Fatty acidsPalm seed oilProduct oilPalmitic acid (C16 : 0)8.096.66Nutmeg acid (C14 : 0)0.550.47Stearic acid (C18 : 0)3.663.27Oleic acid (C18 : 1)18.4521.17Linolenic acid (C18 : 3)24.2225.36Linoleic acid (C18 : 2)42.3643.29Peanut acid (C20 : 0)0.780.64Arachidonic acid (C20 : 1)0.480.34Oleic acid0.260.17It can be seen from Table12 that the fatty acid composition of palm seed oil is similar to that of olive oil, and the palm seed oil contains relatively low saturated fatty acid accounting for about 13.84%. They were mainly palmitic acid and stearic acid. The contents of unsaturated fatty acids were 83.23%, mainly linoleic acid, linolenic acid, and oleic acid [23].


## 5. Conclusions

In this experiment, the extraction rate of palm seed oil was taken as the index, and the orthogonal experiment was used to optimize the extraction conditions of different extraction methods [24].The water enzyme method was the best extraction method of palm seed oil. The single-factor conditions of extraction were as follows: the amount of enzyme added, the time of enzymolysis, and the temperature of enzymolysis. Under these conditions, the extraction rate of palm seed oil was 16.55%. The extraction rate of oil from four different varieties of palm seeds was compared by water enzyme method. It was determined that palmetto microphylla seed was the most suitable extraction material for palm seed oil. The oil of palm seed mainly contains linoleic acid, oleic acid, linolenic acid, and stearic acid by GC-MS analysis. Highly unsaturated fatty acid, basically close to the standard of edible oil, is a good health edible oil. It provides a reference for the development of blend oil with health care function according to proper proportion of edible oil and palm seed oil.



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*Source: 9925974-2021-05-03.xml*