AU2019101752A4

AU2019101752A4 - Preparation method of resveratrol-rich peanut oil

Info

Publication number: AU2019101752A4
Application number: AU2019101752A
Authority: AU
Inventors: Qin Guo; Hui Hu; Yuanrong Jiang; Tian LI; Yujie Li; Hongzhi Liu; Li Liu; Yang Qu; Aimin Shi; Qiang Wang; Yongjun XU
Original assignee: Institute of Food Science and Technology of CAAS
Current assignee: Institute of Food Science and Technology of CAAS
Priority date: 2019-07-10
Filing date: 2019-12-10
Publication date: 2020-11-05
Anticipated expiration: 2027-12-10
Also published as: WO2021004000A1; AU2019101808A4; CN110308221A; AU2019456489A1; WO2021003792A1

Abstract

The invention discloses a preparation method of resveratrol-rich peanut oil, including the steps of: step one, crushing washed and dried peanut roots, and mixing with peanut kernels to obtain a mixture, wherein the mass ratio of the peanut roots and the mixture is 3-11:100; step two, squeezing the mixture at a pressure of 25-40 MPa and a temperature of 50-70°C for 15-35 min to obtain resveratrol-rich peanut oil. The resveratrol-rich peanut oil prepared by the present invention does not need additional additions of resveratrol, and is suitable for industrialized production. 21

Description

PREPARATION METHOD OF RESVERATROL-RICH PEANUT OIL TECHNICAL FIELD

The present invention relates to the field of edible oil, in particular to

a preparation method of resveratrol-rich peanut oil.

BACKGROUND

Peanut oil is the fourth edible oil in the world, its consumption

generally shows a slow growth trend with a compound annual growth rate

of 1.61% (2010-2016). As a major consumer and producer of peanut oil,

China accounts for about 53% of the global total consumption, and the

consumption is expected to reach 6.19 million tons in 2019. With people's

attention to the nutrition and health of edible oil, functional peanut oil is

more and more popular with consumers. In order to obtain more profits,

oil processing enterprises have begun to develop functional edible oil

with high nutritional value, such as a-VE sunflower seed oil of Mighty,

oryzanol rice oil and phytosterol corn oil of Yihai Kerry, etc. The

functional edible oil is a development inevitable trend of the oil

processing industry. As the fourth largest edible vegetable oil in my

country, peanut oil is an urgent need to break through and develop.

Peanuts are rich in many beneficial substances, such as resveratrol,

calcium, zinc, catechins, vitamin E, vitamin K, multiple amino acids and

unsaturated fatty acids. The peanut oil prepared from peanuts also contains phytosterols, wheat germ phenol, phospholipids, vitamin E, choline and other beneficial substances to the human body. Regular consumption of the peanut oil can reduce cholesterol content in plasma, prevent skin from cracking and aging, protect blood vessel walls, prevent thrombosis, improve human brain memory, and delay brain function decline. More than 80% of the peanut oil is unsaturated fatty acids (of which oleic acid is about 41%, linoleic acid is about 37%), which has good composition, and is easy to be absorbed by the human body, thereby regulating blood lipids, clearing thrombus, and enhancing memory and thinking ability.

At present, preparation methods of the functional edible oil mainly

include physical method and chemical method. The physical methods are

mainly to improve preparation process, add functional substances, etc.

Although operation is simple, the improved preparation process requires

expensive equipments, and new harmful substances may be generated on

the basis of destroying the functional substances. The chemical method is

mainly to increase the solubility of functional substances by enzymatic

esterification. Although the effect is significant, reagent residues may

exist. In order to solve the above problems, this study provides a simple

and efficient preparation method of resveratrol-rich peanut oil.

SUMMARY

An object of the present invention is to solve at least above problems,

and to provide, at least, the advantages that will be described later.

An another object of the present invention is to provide a preparation

method of resveratrol-rich peanut oil, which adopts microwave-assisted

treatment of raw materials to effectively promote the generation of free

resveratrol and other trace components in the raw materials, thereby

increasing the content of resveratrol in peanut oil.

In view of object mentioned above and other advantages, the present

invention provides a preparation method of resveratrol-rich peanut oil,

including the following steps of:

step one, crushing washed and dried peanut roots, and mixing with

peanut kernels to obtain a mixture, wherein the mass ratio of the peanut

roots and the mixture is 3-11:100;

step two, squeezing the mixture at a pressure of 25-40 MPa and a

temperature of 50-70°C for 15-35 min to obtain resveratrol-rich peanut

oil.

Preferably, before the step two, the preparation method also includes

a step of performing microwave treatment of the mixture at a power of

300-600 W for 2-8 min.

Preferably, in the step one, the mass ratio of the peanut roots to the

mixture is 9:100.

Preferably, in the step two, the pressure in the squeezing process is

MPa, the temperature is 60°C, and the squeezing time is 20 min.

Preferably, in the step one, the peanut roots are crushed to less than

mesh.

Preferably, before the squeezing process and after the microwave

treatment, the preparation method also includes a step of adding vitamin

E, mixing, and freezing at -10°C for 30 min, wherein the mass ratio of the

mixture to vitamin E is 100:1.

The present invention comprises at least the following substantial

improvements and beneficial effects:

1. Resveratrol is almost undetectable in peanut oil. Peanut roots and

peanuts are simultaneously squeezed in the present invention, which can

enrich resveratrol in peanut oil without external addition, and is suitable

for industrial production.

2. The invention adopts microwave-assisted treatment of raw

materials, which effectively promotes the dissolution of free resveratrol

and other trace components in the raw materials, and increases the

content of resveratrol in peanut oil.

3. The microwave-assisted low-temperature squeezing process

related to the present invention has simple operation, short time

consumption, and low cost; and the process temperature is lower than

°C. The prepared peanut oil does not contain harmful substances such

as trans fatty acids.

4. The resveratrol-rich peanut oil prepared by the present invention

contain resveratrol and other beneficial components in peanuts, its color,

acid value, peroxide value, moisture and volatiles content and heavy

metal content meet the national standard of edible vegetable oil. It has

good nutrition strengthening function, good application value and market

prospects.

Other advantages, objects, and features of the present invention will

be showed in part through following description, and in part will be

understood by those skilled in the art from study and practice of the

present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 shows an effect of the mass ratio of the peanut roots to the

mixture on resveratrol in peanut oil.

Fig. 2 shows an effect of the microwave treatment time on

resveratrol in peanut oil.

Fig. 3 shows an effect of the microwave treatment power on

resveratrol in peanut oil.

Fig. 4 shows an effect of the squeezing time on resveratrol in peanut

oil.

Fig. 5 shows an effect of the squeezing temperature on resveratrol in

peanut oil.

Fig. 6 shows an effect of the squeezing pressure on resveratrol in peanut oil.

Fig. 7 is a response surface diagram showing an effect of an

interaction between the microwave treatment time and the squeezing

temperature on the content of resveratrol in peanut oil.

Fig. 8 is a response surface diagram showing an effect of an

interaction between the mass ratio of the peanut roots to the mixture and

the squeezing temperature on the content of resveratrol in peanut oil.

DETAILED DESCRIPTION

The present invention will now be described in further detail with

reference to the accompanying drawings in order to enable person skilled

in the art to practice with reference to the description.

It should be noted that experimental methods in the following

embodiments are conventional methods unless noted otherwise, and

reagents and materials can be obtained from commercial sources unless

noted otherwise.

The reagents and instruments used in the present invention are as

follows:

Peanut roots: picked from peanut raw material base in Xinjiang in

October 2018;

Peanuts: picked from peanut raw material base in Xinjiang in

October 2018;

The other reagents are chromatographic grade reagents.

centrifuge: LXJ-IIB type from Shanghai Anting Scientific

Instrument Factory;

ultra performance liquid chromatography: ACQUITY H Class,

Waters;

vortex mixer: Vortex-Genie 2, Scientific Industries;

microwave oven: MG720KG3-NA1 from Guangdong Midea

microwave Appliance Manufacturing Co., Ltd.

Embodiment 1

A preparation method of resveratrol-rich peanut oil includes the

following steps of:

step one, crushing washed and dried peanut roots to less than 80

mesh, and mixing with peanut kernels to obtain a mixture, wherein the

mass ratio of the peanut roots to the mixture is 3:100;

step two, squeezing the mixture at a pressure of 25 MPa and a

temperature of 50°C for 15 min to obtain resveratrol-rich peanut oil.

Embodiment 2

A preparation method of resveratrol-rich peanut oil includes the

following steps of:

step one, crushing washed and dried peanut roots to less than 80

mesh, and mixing with peanut kernels to obtain a mixture, wherein the

mass ratio of the peanut roots to the mixture is 11:100;

step two, squeezing the mixture at a pressure of 40 MPa and a temperature of 70°C for 35 min to obtain resveratrol-rich peanut oil.

Embodiment 3

A preparation method of resveratrol-rich peanut oil includes the

following steps of:

step one, crushing washed and dried peanut roots to less than 80

mesh, and mixing with peanut kernels to obtain a mixture, wherein the

mass ratio of the peanut roots to the mixture is 9:100;

step two, squeezing the mixture at a pressure of 40 MPa and a

temperature of 60°C for 20 min to obtain resveratrol-rich peanut oil.

Embodiment 4

The preparation method of resveratrol-rich peanut oil is the same as

that in Embodiment 1. The difference is that before step two, the mixture

is subjected to microwave treatment with a power of 300 W for 2 min.

Embodiment 5

The preparation method of resveratrol-rich peanut oil is the same as

that in Embodiment 2. The difference is that before step two, the mixture

is subjected to microwave treatment with a power of 600 W for 8 min.

Embodiment 6

The preparation method of resveratrol-rich peanut oil is the same as

that in Embodiment 3. The difference is that before step two, the mixture

is subjected to microwave treatment with a power of 500 W for 6 min.

Embodiment 7

The preparation method of resveratrol-rich peanut oil is the same as

that in Embodiment 6. The difference is that before the squeezing process

and after the microwave treatment, vitamin E is added, mixed with the

mixture, and are frozen at -10°C for 30 min, wherein the mass ratio of the

mixture to vitamin E is 100:1.

Comparative example 1

A preparation method of peanut oil includes the following steps of:

squeezing peanut kernels at a pressure of 40 MPa and a temperature of

°C for 20 min to obtain peanut oil.

Quality evaluation of resveratrol-rich peanut oil

The quality of peanut oil prepared from Embodiments 1 to 7 is

detected, and the results are shown in Table 1:

Table 1 Quality index of resveratrol-rich peanut oil Items Quality index Smell, taste original smell and taste of peanut without peculiar smell Moisture and volatiles content /% (less than or equal) 0.10 Insoluble impurities content /% (less than or equal) 0.03 Acid value (KOH)/(mg/g) (less than or equal) 1.1 Peroxide value /(mmol/kg) (less than or equal) 4.0 Residual solvent /(mg/kg) (less than or equal) Not detected

It can be seen from the above table that the quality of the peanut oil

prepared in Embodiments 1-7 all meet the national standard of edible

vegetable oil.

Content evaluation of resveratrol

The content of resveratrol in the peanut oil prepared in Embodiments

1-7 and Comparative Example 1 is tested, and the results are shown in the

following table:

Table 2 the content of resveratrol in Embodiments 1-7 and Comparative

Example 1 Groups Resveratrol (mg/kg) Embodiment 1 0.01 Embodiment 2 0.48 Embodiment 3 0.88 Embodiment 4 0.45 Embodiment 5 0.75 Embodiment 6 0.97 Embodiment 7 1.02 Comparative Example 1 Not detected

It can be seen from the above table that although peanut kernels

contain resveratrol, when the peanut kernels are squeezed into peanut oil,

the content of resveratrol in peanut oil is too small to be detected. The

content of resveratrol in peanut oil prepared from peanut kernels added a

small amount of peanut roots is increased significantly, which indicates

that the appropriate amount of the peanut roots in the raw materials can

increase the content of resveratrol in peanut oil. From the comparison of

Embodiments 4 to 6 with Embodiments 1 to 3, it can be seen that the

microwave treatment can further promote the dissolution of resveratrol

and increase the content of resveratrol in peanut oil.

Stability evaluation of resveratrol

The peanut oil prepared in Embodiments 6 and 7 is baked in an oven

at 180°C for 5 min. The content of resveratrol in each group is detected

after cooling, and the results are shown in the following table:

Table 3 the content of resveratrol in peanut oil prepared in Embodiments

6 and 7 Groups Content of resveratrol in peanut oil (mg/kg) Embodiment 6 0.35 Embodiment 7 0.52

The content of resveratrol in the peanut oil prepared in Embodiments

6 and 7 is significantly reduced after high temperature treatment, but the

reduction in Embodiment 7 is the least, which indicates that the

combination of vitamin E and freezing treatment can reduce the heat loss

of resveratrol.

Single factor test of resveratrol-rich peanut oil

Fig. 1 shows an effect of the mass ratio of the peanut roots to the

mixture on resveratrol in peanut oil. As can be seen from Fig. 1, the

content of resveratrol in peanut oil increases with the increase of the mass

ratio of the peanut roots to the mixture and then does not change. When

the mass ratio of the peanut roots to the mixture is 9%, the content of

resveratrol in peanut oil is up to 1.25 mg/kg. Peanut roots are rich in

resveratrol. When the quality of peanut roots in the mixture is relatively

low, as the proportion of peanut roots increases, the content of resveratrol

in peanut oil continues to increase. Since resveratrol is hard to dissolve in

peanut oil, the content of resveratrol in peanut oil will not continue to

increase after reaching a certain degree of saturation.

Fig. 2 shows an effect of the microwave treatment time on

resveratrol in peanut oil. As can be seen from Fig. 2, the content of resveratrol in peanut oil increases with the extension of microwave treatment time, and the maximum content is 0.65 mg/kg at 6 min. The structure of peanut cells can be destroyed by the microwave treatment, and the dissolution of free resveratrol can be promoted. After reaching a certain degree of saturation, the content of resveratrol does not increase.

Fig. 3 shows an effect of the microwave treatment power on

resveratrol in peanut oil. As can be seen from Fig. 3, the content of

resveratrol in peanut oil increases with the increase of microwave

treatment power, and the highest resveratrol content is 0.71 mg/kg at 500

W. With the increase of microwave treatment power, the content of

resveratrol no longer changes significantly. As more suitable microwave

power for microwave equipment is 500 W, in order to extend the service

life of the equipment, 500 W is selected as the best microwave power.

Fig. 4 shows an effect of the squeezing time on resveratrol in peanut

oil. As can be seen from Fig. 4, the content of resveratrol in peanut oil

does not change much with the extension of pressing time. When the

squeezing time is within 15 minutes, the oil is produced quickly, and the

fat in the peanuts is squeezed out of 65-75%. When the squeezing time is

minutes, the content of resveratrol reaches the maximum value of 0.73

mg/kg. As the squeezing time increases, the oil output is slower, and it is

not conducive to continuous production, so 20 min is selected as the best

squeezing time.

Fig. 5 shows an effect of the squeezing temperature on resveratrol in

peanut oil. As can be seen from Fig. 5, the content of resveratrol in peanut

oil first increases and then decreases with the increase of the squeezing

temperature, and reaches the maximum value of 0.77 mg/kg when the

squeezing temperature is 60°C. Suitable temperature promotes the

dissolution of resveratrol. But when the temperature is too high,

resveratrol is unstable, and the content of resveratrol in peanut oil is

reduced.

Fig. 6 shows an effect of the squeezing pressure on resveratrol in

peanut oil. As can be seen from Fig. 6, the content of resveratrol in peanut

oil first increases with the increase of squeezing pressure and then does

not change. When the squeezing pressure is 40 MPa, the maximum value

is 0.66 mg/kg. The increase in squeezing pressure is accompanied by the

increase in physical extrusion strength, which is beneficial to the

dissolution of resveratrol in the peanut mixture. 40 MPa is the highest

safety pressure of hydraulic equipment. In order to extend the service life

of the equipment, this pressure is the best choice.

According to the principle of Box-Behnken Center Design, on the

basis of the single factor test results, three factors (the mass ratio of

peanut roots to the mixture, the microwave treatment time, and the

squeezing temperature) that have a greater impact on the content of

resveratrol in peanut oil, are selected as independent variables, and the content of resveratrol in peanut oil is a response value. Three-factor three-level response surface design is performed using Design Expert software, as shown in Table 4:

Table 4 test factors level

Level X1 mass ratio of peanut roots X2 microwave treatment X 3 squeezing to mixture /% time /min temperature / °C -1 8 5 57 0 9 6 60 1 10 7 63

Response surface test results are as the following table:

Table 5 Three-factor three-level response surface design and results

Serial number X1 X2 X3 Y/(mg/kg)

1 -1.0 -1.0 0.0 0.06 2 -1.0 0.0 1.0 0.01 3 -1.0 1.0 0.0 0.12 4 0.0 0.0 0.0 0.97 5 -1.0 0.0 -1.0 0.29 6 0.0 0.0 0.0 1.02 7 1.0 0.0 -1.0 0.17 8 1.0 -1.0 0.0 0.16 9 0.0 0.0 0.0 1.00 10 1.0 1.0 0.0 0.23 11 0.0 0.0 0.0 1.03 12 1.0 0.0 1.0 0.19 13 0.0 1.0 1.0 0.33 14 0.0 -1.0 -1.0 0.28 15 0.0 1.0 -1.0 0.22 16 0.0 0.0 0.0 0.96 17 0.0 -1.0 1.0 0.02

A quadratic polynomial regression equation of the content of

resveratrol in peanut oil versus the independent variables of the mass

ratio of the peanut roots to the mixture, the microwave treatment time and the actual value of the squeezing temperature is obtained by multivariable regression fitting of the test data in Table 5 (Design Expert software):

Y=-177.03+6.62X+3.01X 2+4.65X 3+0.02XX 3+0.03X 2X3-0.45X1 2 -0

.40X2 2 -0.04X 3 2

Table 6 response surface quadratic model variance analysis of the content

of resveratrol in peanut oil

Source of Degree of Mean Sum of squares F value P value Significance variance freedom square

Model 2.50 9 0.28 197.80 < 0.0001 **

XI 0.009 1 0.009 6.48 0.0384

* X2 0.018 1 0.018 12.83 0.0089 **

X3 0.021 1 0.021 14.94 0.0062 **

2.50x10-s X1X 2 2.50x10-5 1 0.018 0.8977 NS

X1 X 3 0.022 1 0.022 16.00 0.0052 **

X 2X 3 0.034 1 0.034 24.33 0.0017 **

X 12 0.85 1 0.85 607.59 < 0.0001 **

X22 0.68 1 0.68 486.22 < 0.0001 **

X32 0.61 1 0.61 433.44 < 0.0001 **

Residual error 9.85x10-3 7 1.41x10-3

Simulating 6.12x10-3 3 2.04x10-3 2.20 0.2311 NS loses

Pure error 3.72x10-3 4 9.30x10-4

Total error 2.51 16 NS: no significant difference, P is more than 0.05; *: significant difference, P is less than 0.05; **: extremely significant difference, P is less than 0.01; R2 is 0.9961; Adj R2 is 0.9910; and C.V.% is 9.03.

The analysis results of variance on the model are shown in Table 6.

The model is extremely significant (P is less than 0.0001), and the

influence of each factor on Y is not a simple linear relationship. The

coefficient of determination R 2 of the equation is 0.9961, which indicates that the regression model can explain the relationship between the independent variables and Y. The adjusted coefficient of determination

Adj R2 is 0.9910, which indicates that the model has good fit. Simulating

loses of the model P is 0.2311, which is more than 0.05, and indicates that

the simulating loses of the model is not significant. The coefficient of

variation C.V. of the model is 9.03%, which is less than 10%, and

indicates that the quadratic polynomial model is acceptable. Therefore,

the model can more accurately analyze and predict the content of

resveratrol in peanut oil.

Fig. 7 is a response surface diagram showing an effect of an

interaction between the microwave treatment time and the squeezing

temperature on the content of resveratrol in peanut oil. The analysis of

influence of the interaction between the microwave treatment time and

squeezing temperature on the content of resveratrol in peanut oil shows

that: When the microwave treatment time is fixed, the content of

resveratrol in peanut oil first increases and then decreases with the

increase of the squeezing temperature; and when the squeezing

temperature is fixed, the content of resveratrol in peanut oil first increases

and then decreases with the extension of microwave treatment time. The

influence of squeezing temperature is more significant than that of

microwave treatment time.

Fig. 8 is a response surface diagram showing an effect of an interaction between the mass ratio of the peanut roots to the mixture and the squeezing temperature on the content of resveratrol in peanut oil. The analysis of influence of the interaction between the mass ratio of the peanut roots to the mixture and the squeezing temperature on the content of resveratrol in peanut oil shows that: When the mass ratio of the peanut roots to the mixture is fixed, the content of resveratrol in peanut oil first increases and then decreases with the increase of the squeezing temperature; and when the squeezing temperature is fixed, the content of resveratrol in peanut oil first increases and then decreases with the mass ratio of the peanut roots to the mixture.

The results shows that the best parameters obtained by using Design

Expert software to analyze and predict are: the mass ratio of the peanut

roots to the mixture is 9.03%, the microwave treatment time is 6.05 min,

and the squeezing temperature is 59.82°C. However, considering the

actual operation and equipment errors, the process conditions are adjusted

as follows: the mass ratio of the peanut roots to the mixture is 9%, the

microwave treatment time is 6 min, the squeezing temperature is 60°C,

and the content of resveratrol in peanut oil reaches 1.00 mg/kg. The

predicted results are not significantly different from the actual results,

which indicates that the model is more reliable and can be used to predict

the preparation process.

Although the embodiments of the present invention have been disclosed above, they are not limited to the applications previously mentioned in the specification and embodiments, and can be applied in various fields suitable for the present invention. For ordinary skilled person in the field, other various changed model, formula and parameter may be easily achieved without creative work according to instruction of the present invention, changed, modified and replaced embodiments without departing the general concept defined by the claims and their equivalent are still included in the present invention. The present invention is not limited to particular details and illustrations shown and described herein.

Claims

WHAT IS CLAIMED IS:

1. A preparation method of resveratrol-rich peanut oil, being

characterized in that, the preparation method includes the steps of:

step one, crushing washed and dried peanut roots, and mixing with

peanut kernels to obtain a mixture, wherein the mass ratio of the peanut

roots and the mixture is 3-11:100;

step two, squeezing the mixture at a pressure of 25-40 MPa and a

temperature of 50-70°C for 15-35 min to obtain resveratrol-rich peanut

oil.

2. The preparation method of resveratrol-rich peanut oil according to

claim 1, being characterized in that, before the step two, the preparation

method also includes a step of performing microwave treatment of the

mixture at a power of 300-600 W for 2-8 min.

3. The preparation method of resveratrol-rich peanut oil according to

claim 1, being characterized in that, in the step one, the mass ratio of the

peanut roots to the mixture is 9:100.

4. The preparation method of resveratrol-rich peanut oil according to

claim 1, being characterized in that, in the step two, the pressure in the

squeezing process is 40 MPa, the temperature is 60°C, and the squeezing

time is 20 min.

5. The preparation method of resveratrol-rich peanut oil according to

claim 1, being characterized in that, in the step one, the peanut roots are crushed to less than 80 mesh.

6. The preparation method of resveratrol-rich peanut oil according to

claim 2, being characterized in that, before the squeezing process and

after the microwave treatment, the preparation method also includes a

step of adding vitamin E, mixing, and freezing at -10°C for 30 min,

wherein the mass ratio of the mixture to vitamin E is 100:1.