Influence of natural and synthetic antioxidants on the degradation of Soybean oil at frying temperature

Effectiveness of different antioxidants in suppressing the evolution of thermally induced peroxidation products in hemp seed oil

Several scientific studies have warned that the ingestion of dietary lipid oxidation products (LOPs) may initiate or exacerbate the development of several chronic non-communicable diseases in humans. Indeed, the constantly increasing consumption of culinary oils by larger global populations indicates the need for scientific techniques to suppress the evolution of LOPs in thermo-oxidised oils. This study employed a 600.13 MHz frequency NMR spectrometer in evaluating the effect of 10, 50, and 100 ppm concentrations of chemical compounds reported to have antioxidant properties in continuously-stirred and thermally stressed polyunsaturated fatty acid (PUFA)-rich hemp seed oil at a frying temperature of 180℃ for 180 min. Research data acquired showed that the antioxidants α- and γ-tocopherol, γ-oryzanol, β-carotene, eugenol, resveratrol, ascorbyl palmitate, gentisic acid, and L-ascorbic acid all played a vital role in suppressing the evolution of secondary aldehydic lipid oxidation products in hemp seed oil. However, the most ineffective LOP-suppressing agent was L-lysine, an observation which may be accountable by its poor oil solubility. Nonetheless, trends deduced for compounds acting as antioxidants were mainly unique for each class of agent tested. Conversely, the antioxidant capacity of resveratrol was consistently higher, and this effect was found to be independent of its added amounts. This report provides a direct approach in developing scientific methods for the suppression of LOPs in thermo-oxidatively susceptible PUFA-rich cooking oils.

Lipid concomitant γ-oryzanol decreased oil absorbency of French fries by changing the microstructure of French fries and physical properties of frying oil

BACKGROUND

The aim of this research was to evaluate the possibility of lipid concomitant γ-oryzanol reducing oil absorbency of fried foods and the underlying mechanism. Therefore, the influence of γ-oryzanol on moisture and oil content, and distribution and micromorphology of French fries and the viscosity, fatty acid composition and total polar compounds content of rice bran oil (RBO) after frying were studied.

RESULTS

Our results showed that the incorporation of low concentration of γ-oryzanol [low addition group (LAG)] (5.754 g/kg) decreased the oil absorbency and porous structure of French fries during frying. Additionally, LAG incorporation inhibited the degradation of linoleic acid, decreased the growth rate of saturated fatty acids, total polar compounds and viscosity of frying oil.

CONCLUSIONS

Consequently, it was recommended to incorporate a small amount of γ-oryzanol in frying oil because it could inhibit oil absorption behavior of French fries. © 2023 Society of Chemical Industry.

Effects of tea polyphenols and tertiary butylhydroquinone on quality of palm oils and losses of endogenous vitamin E during batch frying and oxidative stability of fried instant noodles

The effects of tea polyphenols (TP) on the quality of palm oils (PO) and losses of endogenous vitamin E during batch frying of instant noodles as well as oxidative stability of fried instant noodles were investigated. PO without antioxidant addition was negative control and with tertiary butylhydroquinone (TBHQ) addition positive control. TP and TBHQ addition inhibited the increase of peroxide, p-anisidine, and total oxidation values of PO and reduced tocopherol and tocotrienol losses with 200 mg/kg of TP having the best performance, but didn't affect acid value and triglyceride composition. 200 mg/kg of TP and 100 mg/kg of TBHQ inhibited unsaturated fatty acid losses. During frying, TBHQ was mainly volatilized but TP transformed. TP more effectively reduced tocopherol and tocotrienol losses than TBHQ, reducing PO deterioration. The extended lifecycles of PO and shelf life of fried instant noodles are attributed to nonvolatility of TP and antioxidative properties of its transformation products.

Preserving Soybean Oil for the Frying of Breaded Butterfly Shrimp Using Natural Rosemary Antioxidant

Fried foods and frying oil are subjects that warrant the attention of researchers because of their high consumption. Indeed, frying conditions make these oils very sensitive to lipid oxidation which deteriorates the quality and nutritional properties of the food. In this study, we examined the effect of rosemary extract (ROE), known for its high antioxidant activity, in soybean oil used to fry breaded butterfly shrimp, by measuring the induction period with OXIPRES, total polar material (TPM), peroxide index (PI), and free fatty acids (FFA). This evaluation was performed in comparison with control oils without antioxidants. The results showed a significant difference between the oils according to the analyzed parameters, especially in the final hours of frying. The treatment of the oil with rosemary extract effectively delayed its oxidation, having lower levels in all the oxidation markers that were analyzed. It was also found that rosemary extract is able to reduce oil consumption by fried foods. Therefore, ROE ensures soybean oil a high stability against oxidation and a longer shelf life, making it a good natural alternative to synthetic antioxidants.

Exploring the Potential of Grape Pomace Extract to Inhibit Thermo-Oxidative Degradation of Sunflower Oil: From Routine Tests to ATR-FTIR Spectroscopy

Exploring new sources of natural antioxidants is of great interest to edible oil producers, in line with the toxicological problems generated by the use of synthetic antioxidants. This study assesses the potential of lyophilized Pinot Noir grape pomace extract (GPE) to enhance the sunflower oil stability against thermo-oxidative damage compared to BHT during a prolonged exposure to convective heat at 185 °C. Oil thermo-oxidation was monitored based on specific indices such as peroxide value (PV), para-anisidine value (p-AV), inhibition of oil oxidation (IO), total oxidation (TOTOX) value, conjugated dienes and trienes (CDs, CTs), but also by attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), where absorbance ratios A 3009 cm^-1/A 2922 cm^-1 (RI), A 3009 cm^-1/A 2853 cm^-1 (RII), A 3009 cm^-1/A 1744 cm^-1 (RIII) and RIV = A 1744 cm^-1/A 2922 cm^-1 (RIV) were investigated. GPE showed a significant inhibitory effect on oil thermo-oxidation and this response was concentration-dependent. Substantial decreases in the investigated indices, compared to the control without added antioxidants, were obtained after 4 h and 8 h of heat exposure of the 800 ppm GPE sample: PV (47%; 42%), p-AV (38%; 33%), IO (54%; 46%), TOTOX (41%; 37%), CDs (46%; 39%), CTs (44%; 29%). Oil exposure to heat resulted in changes in RI-RIV attributed to the reduction in the degree of unsaturation, in response to primary and secondary lipid oxidation. FTIR spectroscopy can be used to differentiate untreated and heat-treated oils based on the absorbance ratios. An inhibitory effect close to that of BHT was achieved by 500 ppm GPE, while a dose of 800 ppm provided greater protection against thermo-oxidation. Our results promote GPE as a natural additive to limit the thermo-oxidative damage of plant oils.

Effect of tunisian pomegranate peel extract on the oxidative stability of corn oil under heating conditions

The effect of pomegranate peel extract (PPE) on the oxidative stability of corn oil during heating was studied. Oxidation was followed by determining peroxide value (PV), p-anisidine value (p-AV), free fatty acid value (FFA), conjugated dienes (CD), conjugated trienes hydroperoxides (CT) and the calculated total oxidation value (TOTOX). Polyphenol (TPC) and ortho-diphenol (TOPC) contents as well as the antioxidant activity of each oil sample were evaluated before and after heating. PPE showed a significant inhibitory effect on lipid oxidation. Heating samples for 8 hours supplemented by PPE to a level of 1000 ppm resulted in the highest significant decreases in investigated indices compared to the control and BHT values. It was concluded that the antioxidant activity of PPE delayed oxidation and can be used in the food industry to prevent and reduce lipid deterioration in oil.

Exploring the Effect of Methyl Jasmonate on the Expression of microRNAs Involved in Biosynthesis of Active Compounds of Rosemary Cell Suspension Cultures through RNA-Sequencing

Our aim in the experiment was to study the effects of methyl jasmonates (MeJA) on the active compounds of rosemary suspension cells, the metabolites' change of contents under different concentrations of MeJA, including 0 (CK), 10 (M10), 50 (M50) and 100 μM MeJA (M100). The results demonstrated that MeJA treatments promoted the accumulation of rosmarinic acid (RA), carnosic acid (CA), flavonoids, jasmonate (JA), gibberellin (GA), and auxin (IAA); but reduced the accumulations of abscisic acid (ABA), salicylic acid (SA), and aspartate (Asp). In addition, 50 and 100 μM MeJA promoted the accumulation of alanine (Ala) and glutamate (Glu), and 50 μM MeJA promoted the accumulation of linoleic acid and alpha-linolenic acid in rosemary suspension cells. Comparative RNA-sequencing analysis of different concentrations of MeJA showed that a total of 30, 61, and 39 miRNAs were differentially expressed in the comparisons of CKvsM10, CKvsM50, CKvsM100, respectively. The analysis of the target genes of the differentially expressed miRNAs showed that plant hormone signal transduction, linoleic acid, and alpha-linolenic acid metabolism-related genes were significantly enriched. In addition, we found that miR160a-5p target ARF, miR171d_1 and miR171f_3 target DELLA, miR171b-3p target ETR, and miR156a target BRI1, which played a key role in rosemary suspension cells under MeJA treatments. qRT-PCR of 12 differentially expressed miRNAs and their target genes showed a high correlation between the RNA-seq and the qRT-PCR result. Amplification culture of rosemary suspension cells in a 5 L stirred bioreactor showed that cell biomass accumulation in the bioreactor was less than that in the shake flask under the same conditions, and the whole cultivation period was extended to 14 d. Taken together, MeJA promoted the synthesis of the active compounds in rosemary suspension cells in a wide concentration range via concentration-dependent differential expression patterns. This study provided an overall view of the miRNAs responding to MeJA in rosemary.

Transcriptome Analysis Reveals Differentially Expressed Genes That Regulate Biosynthesis of the Active Compounds with Methyl Jasmonate in Rosemary Suspension Cells

To study the effects of Methyl jasmonates (MeJA) on rosemary suspension cells, the antioxidant enzymes’ change of activities under different concentrations of MeJA, including 0 (CK), 10 (M10), 50 (M50) and 100 μM MeJA (M100). The results demonstrated that MeJA treatments increased the activities of phenylalanine ammonla-lyase (PAL), superoxide dismutase (SOD), peroxidase (POD), catalase (CAT) and polyphenol oxidase (PPO) and reduced the contents of hydrogen peroxide (H₂O₂) and malondialdehyde (MDA), thus accelerating the ROS scavenging. Comparative transcriptome analysis of different concentrations of MeJA showed that a total of 7836, 6797 and 8310 genes were differentially expressed in the comparisons of CKvsM10, CKvsM50, CKvsM100, respectively. The analysis of differentially expressed genes (DEGs) showed phenylpropanoid biosynthesis, vitamin B6, ascorbate and aldarate metabolism-related genes were significantly enriched. The transcripts of flavonoid and terpenoid metabolism pathways and plant hormone signal transduction, especially the jasmonic acid (JA) signal-related genes, were differentially expressed in CKvsM50 and CKvsM100 comparisons. In addition, the transcription factors (TFs), e.g., MYC2, DELLA, MYB111 played a key role in rosemary suspension cells under MeJA treatments. qRT-PCR of eleven DEGs showed a high correlation between the RNA-seq and the qRT-PCR result. Taken together, MeJA alleviated peroxidative damage of the rosemary suspension cells in a wide concentration range via concentration-dependent differential expression patterns. This study provided a transcriptome sequence resource responding to MeJA and a valuable resource for the genetic and genomic studies of the active compounds engineering in rosemary.

Soybean Oil Enriched with Antioxidants Extracted from Watermelon (Citrullus colocynthis) Skin Sap and Coated in Hydrogel Beads via Ionotropic Gelation

Many plants and fruits are rich in antioxidant and antimicrobial compounds, such as phenolic compounds. Watermelon is one example, as various parts of the fruit present interesting phytochemical profiles. This study demonstrates that a natural C. colocynthis (watermelon) (W) skin sap (SS) extract can effectively improve the oxidative stability of microencapsulated soybean (SB) oil. By employing a combination of alginate–xanthan gums (AXG) in a matrix hydrogel bead model with WSS extract, high encapsulation efficiency can be obtained (86%). The effects of process variables on the ultrasound-assisted extraction (UAE) of phenolic compounds from watermelon (W) skin sap (SS) using the response surface methodology (RSM), as an optimized and efficient extraction process, are compared with the effects of a conventional extraction method, namely the percolation method. The WSS extracts are obtained via UAE and RSM or the conventional percolation extraction method. The two obtained extracts and synthetic antioxidant butylated hydroxytolune (BHT) are added to SB oil separately and their antioxidant effects are tested and compared. The results show the improved oxidative stability of SB oil containing the extract obtained via the optimized method (20–30%) compared to the SB oil samples containing extract obtained via the percolation extraction method, synthetic antioxidant (BHT), and SB oil only as the control (no antioxidant added). According to existing studies, we assume that the use of WSS as an effective antioxidant will ensure the prolonged stability of encapsulated SB oil in hydrogel beads, as it is well known that extended storage under different conditions may lead to severe lipid oxidation.

Antioxidant Capacity of Tempura Deep-Fried Products Prepared Using Barley, Buckwheat, and Job’s Tears Flours

Tempura is a dish of battered and deep-fried foods, and wheat flour is typically used; however, barley, buckwheat, and Job’s tears have an antioxidant capacity. This study investigated whether replacing wheat flour with flours from these three crops in tempura affects the antioxidant capacity and deterioration of frying oil. Radical scavenging activity and polyphenol content of tempura were measured by chemiluminescence-based assay and the Folin–Denis method, respectively. The peroxide value, p-anisidin value, acid value, and polar compound of the oil used in frying were measured as indexes of oil deterioration post-frying due to oxidation. Although the frying oil of barley showed higher p-anisidin value than that of wheat, the oil samples’ deterioration level measured in this study was low. The antioxidant capacity and polyphenol content in the three flours samples were higher than those in wheat sample, with buckwheat producing the greatest values, followed by Job’s tears, and then barley. Thus, deep-fried products prepared using the three flours demonstrated superior antioxidant capacity owing to the abundance of antioxidant components. Therefore, tempura can be enjoyed in a healthier manner by using batter prepared using those flours, and substituting wheat flour with the three flours can increase the antioxidant capacity of deep-fried products.