As a traditional food cooking or processing method, frying has a strong appeal
to most consumers due to its short time consumption, ease of operation and unique taste of the product.
However, in general, with the extension of frying time, frying oil will undergo a series of chemical reactions, including thermal oxidation of triglycerides, hydrolysis reaction and Maillard reaction; If these reactions are excessive, some hazardous substances may be produced and seriously threaten the health of
Acrylamide (AA), a colorless, odorless, low-molecular mass crystalline compound, has been classified by IARC as a Group 2A "probable human carcinogen.
The production amount of AA is affected by temperature, heating time, asparagine, reducing sugar and other factors, so in actual production, the production
of AA can be controlled by adjusting these factors 。 Daisha Qi, Shuyun Li and Qing Zhang* from the College of Food Sciences, Sichuan Agricultural University, analyzed the antioxidant properties of pomegranate episol extract (EEPP); It was then added to soybean oil at a certain concentration for deep frying fries, and the effects of different concentrations of EEPP on the thermal oxidation stability and AA formation in fries were evaluated, aiming to provide a theoretical basis
for the rational use of fruit processing by-products and the expansion of the application of plant alcohol extracts in frying oil and frying food quality control.
Analysis of antioxidant activity of extract
As shown in Figure 1, the scavenging rate of EEPP to DPPH radicals and ABTS cation radicals was higher than that of VC in the mass concentration range of 0.
4 mg/mL, and when the mass concentration exceeded 0.
4 mg/mL, the scavenging rates of EEPP and VC on DPPH radicals were above 90%, reaching 96.
96% and 95.
The highest scavenging rates of ABTS cation radicals were 90.
03% and 89.
The FRAP standard curve equation is y=0.
As shown in Figure 2, at low mass concentration (0.
1 mg/mL), the FRAP value of EEPP is higher than that of VC, and when the mass concentration exceeds 0.
1 mg/mL, VC is always higher than EEPP, but the difference is not large
With the increase of mass concentration, FRAP increased accordingly, and the FRAP values of EEEP and VC were 8.
24 mmol/g and 10.
, respectively, at a mass concentration of 1.
Thermal oxidation stability of frying oil
EEPP on prolonging the use time of frying oil 。 In addition, the AV content of 0.
02% EEPP frying oil (0.
882 mg/g) was higher than that of other treatment groups (0.
085 mg/g) during frying.
Compared with other concentrations of EEPP experimental group, frying oil with 0.
14% EEPP had the lowest AV level, and compared with the TBHQ experimental group, the growth trend was slower
than that without antioxidants.
This shows that 0.
14% EEPP has a certain inhibitory effect on the decomposition of free fatty acids, and has obvious inhibition of oil hydrolysis and deep oxidative rancidity of unsaturated fats, and its inhibitory effect may be comparable to or even better
It can be seen from Figure 3B that the POV variation trend of frying oil in the EEPP experimental group with different dosages
fluctuates in the process of fries frying.
Compared with the negative control group (0.
250 g/100 g), the frying oil with EEPP and TBHQ had a smaller POV variation range (0.
139 g/100 g).
。 Compared with the frying oil with TBHQ (0.
126 g/100 g), the frying oil with 0.
14% EEPP showed a small variation (0.
123 g/100 g), which indicated that the addition of EEPP could inhibit the oxidation of oils and fats, showing a strong antioxidant effect, and 0.
14% EEPP may show a better ability to inhibit POV than TBHQ, possibly due to the high addition of EEPP with more bioactive components.
Greater ability to scavenge free
As shown in Figure 3C, the TPC content increases with the extension of the frying time, which is consistent with the findings of Osawa et al.
, which may be due to the oxidation of the oil and fat to produce peroxides due to the extension of the frying time, and its decomposition and polymer will increase the polar compounds
According to GB 2716-2018 "Vegetable Oil", the maximum TPC content of frying oil cannot exceed 27%.
After continuous frying for nearly 2 days, the TPC content of all treatment groups exceeded 27%, indicating that the frying oil had exceeded the use limit
at this time.
The effect of EEPP on the formation of AA
As shown in Figure 4, AA Reference Standards were detected at 7 min
The calibration curve was drawn according to the relationship between peak area and AA mass concentration (0.
05~10 μg/mL), expressed as y=3.
where the x-axis is the AA mass concentration (μg/L) and the y-axis is the peak area
Figure 5 shows the change
in AA content in fries and frying oil during 3 days frying (10 h/d).
At the end of the frying process, the AA content in the fries samples of the negative control group, EEPP treatment group (0.
07% and 0.
14%) and the positive treatment group were 0.
15, and 0.
The AA content in the frying oil of the negative control group and the EEPP treatment group (0.
03% and 0.
07%) were 1.
30 and 1.
87 μg/g, respectively, and AA was not detected
in the other treatment groups 。 Relatively few samples of AA were detected in frying oil, and the possible reasons are: AA is hydrophilic, difficult to dissolve in frying oil, and easy to be absorbed by fries and exists in the fries matrix and is easy to decompose at high temperature; EEPP indirectly reduces the amount of AA produced by inhibiting the oxidative decomposition of polyunsaturated fats, further reducing the possibility of
AA being present in frying oil.
EEPP has strong DPPH radical, ABTS cationic radical scavenging ability and FRAP, which can delay the hydrolytic oxidation reaction
14% EEPP before frying can slow down the rate of oxidative deterioration of frying oil, improve the thermal oxidative stability to a certain extent, and effectively inhibit the formation of AA in fries and frying oil, with an inhibition rate of 83%, which is higher than that of TBHQ experimental group (60%)
It can be seen that EEPP can effectively exert strong antioxidant activity in the frying process, and as a potential natural antioxidant, it has broad application prospects and development value
This study is conducive to the in-depth development and utilization of pomegranate peel and provides a new way for the rational application of fruit processing by-products.
However, the specific antioxidant active ingredients and mechanism of action in EEPP need to be further studied
About the corresponding author
Qing Zhang, Ph.
, Associate Professor, Visiting Scholar, University of Alberta, Canada; Reserve candidate for academic and technical leaders in Sichuan Province
His research interests include plant protein/polysaccharide interaction modification and its application in food processing and nanodelivery of bioactive substances, and quality analysis and control
of frying oil and fried food.
He has presided over 10 national, provincial and ministerial projects such as the National Natural Science Foundation of China Youth Fund, and 4 local or enterprise cooperation projects
He has published more than 50 scientific papers as the first author or corresponding author (including 30 papers included in SCI; Top 14 articles in the 1st district of the large category division of the Chinese Academy of Sciences); As the first inventor, he has obtained 2 authorized national invention patents and 9 utility model patents; He has edited 1 textbook ("Agricultural Product Processing Technology"), participated in the compilation of 4 textbooks ("Fruit and Vegetable Storage and Processing", "Grain and Oil Processing", etc.
), and participated in the editing of 1 academic monograph published by Elsevier (Reference Module in Food Science).
Participated in winning 1 first prize and 1 second prize of Sichuan Science and Technology Progress Award; Won the first prize of Sichuan Agricultural University Undergraduate Teaching Quality Award once; He has been supervised by 1 excellent master's thesis and 2 bachelor's theses
Invited to review National Science Center (Poland) OPUS fund projects; Member of the editorial board of the international journal Egyptian Journal of Food Science; Young editorial board member of the domestic journal "Journal of Light Industry", reviewer of "Food and Fermentation Industry"; Reviewer
for international journals such as Trends in Food Science & Technology, Critical review of Food Science and Nutrition, and Food Chemistry.
First author bio
Qi Daisha is a 2019 master's student in food science and engineering at Sichuan Agricultural University, and a member of the research team of postharvest treatment and quality control of agricultural products in the College of Food Science of Sichuan Agricultural University, mainly engaged in the research
of frying oil and quality control of fried food.
This article "Effect of Pomegranate Episol Extract on Oxidative Stability and Acrylamide Content of Frying Oil during Deep Frying of French Fries" is from Food Science, Vol.
16, 2022, pages 122-128, authors: Qi Daisha, Li Shuyun, Zhang Qing
。 Click to view information about