Physio-Chemical Changes During Repeated Frying of Cooked Oil: A Review

Potential of polyphenols from Ligustrum robustum (Rxob.) Blume on enhancing the quality of starchy food during frying

The increasing concerns about health have led to a growing demand for high-quality fried foods. The potential uses of Ligustrum robustum (Rxob.) Blume, a traditional tea in China, as natural additives to enhance the quality of starchy food during frying was studied. Results indicated that L. robustum polyphenols extract (LREs) could improve the quality of fried starchy food, according to the tests of color, moisture content, oil content, texture property, and volatile flavor. The in vitro digestion results demonstrated that LRE reduced the final glucose content from 11.35 ± 0.17 to 10.80 ± 0.70 mmol/L and increased the phenolic content of fried starch foods from 1.23 ± 0.04 to 3.76 ± 0.14 mg/g. The appearance and polarizing microscopy results showed that LRE promoted large starch bulges on the surface of fried starchy foods. Meanwhile, X-ray diffraction results showed that LRE increased the intensity of characteristic diffraction peak of fried starch with a range of 21.8%-28%, and Fourier transform infrared results showed that LRE reduced the damage to short-range order structure of starch caused by the frying process. In addition, LRE increased the aggregation of starch granules according to the SEM observation and decreased the enthalpy of starch gelatinization based on the differential scanning calorimetry results. The present results suggest that LREs have the potential to be utilized as a natural additive for regulating the quality of fried starchy food in food industries. PRACTICAL APPLICATION: The enhancement of L. robustum polyphenols on the quality of starchy food during frying was found, and its mechanisms were also explored. This work indicated that L. robustum might be used as a novel economic natural additive for producing high-quality fried foods.

Long-term Supplementation of Deep-fried Oil Consumption Impairs Oxidative Stress, Colon Histology and Increases Neurodegeneration

BACKGROUND

Sesame oil and sunflower oil are popular cooking oils in southern India. Deep-frying is a frequent method of food preparation. Deep-frying at high temperatures has been linked with several disorders, including cancer, diabetes, and unknown metabolic problems. There have been no long-term investigations on the influence of deep-fried oils on PUFA metabolism and pathogenesis. As a result, the current study aimed to explore the effect of deep-fried frying oil on Wistar rats by continuous treatment. Furthermore, the pathophysiology of MSG-induced neurotoxicity in Wistar rats was investigated.

METHODS

Wistar rats weighing 200-260 g were used in this study. Female rats were divided into five groups fed with (1) standard chow (control group), (2) unheated sesame oil (UHSO) along with standard chow, and (3) reheated sesame oil (RHSO) along with standard chow, (4) unheated sunflower oil (UHSFO) along with standard chow, and (5) reheated sunflower oil (RHSFO) along with standard chow and continued up to F1 generation. Furthermore, F1 male rats were treated with MSG of 2 g/kg body weight for 10 alternative days and were sacrificed for major tissues.

RESULTS

We found that rats treated with RHSO and RHSFO showed increased body weight. Deep-fried oil-fed rats (RHSO and RHSFO) showed a significant increase in total cholesterol- 100 mg/dl, LDL- 23 mg/dl, & TAG-100 mg/dl, when compared to unheated oil rats. Liver function tests revealed that AST and ALT levels were significantly elevated in RHSO and RHSFO when compared to unheated oils and the control group. Inflammatory markers revealed that Hs-CRP (0.35 mg/dl) and LDH levels (6000 U/L) were significantly elevated in RHSO and RHSFO when compared to the unheated oils and control group. RT-PCR results showed significant elevation in the antioxidant genes SOD (twofold) and GPX (3-fold) when compared to UHSO and UHSFO groups. Liver and colon histology showed significant damage in the cell structure of RHSO and RHSFO-treated rats. Further, rats treated with unheated oils and MSG showed statistically significantly higher mRNA expression of neuroplasticity genes CREB, BDNF and reduced NMDA levels (UHSO, UHSFO) when compared to reheated oil groups (RHSO & RHSFO). Proinflammatory marker TNF-α expression was significantly elevated in RHSFO-treated rats when compared to control. Brain histology showed focal damage in glial cell degeneration in rats treated with RHSO and RHSFO when compared to other groups.

CONCLUSION

The results from the present study proved that continuous supplementation deep-fried reheated oil consumption increased serum TGL and oxidative stress markers. Impaired liver metabolism and the involvement of the gut-liver-brain axis increased the risk of neurodegeneration.

Underutilised palm stearin as hard stock for deep-frying medium and its performance for oil uptake in instant noodles

BACKGROUND

As a by-product of the palm oil industry, palm stearin is often overlooked despite having several beneficial properties, such as excellent stability, which is critically essential to meet the demand of the global food trend in producing safer processed food. Specifically, deep frying of food is often associated with the production of toxic compounds that could potentially migrate into the food system when oils are degraded under continuous heating. The incorporation of palm stearin is regarded as a cost-effective and efficient method to modify the fatty acid composition of oils, enhance the frying qualities and lower the degradation rate.

RESULTS

This study blended 5% and 10% palm stearin into palm oil to investigate the deep-frying performance and impact on food quality. Increasing the palm stearin content improved the frying oil's oxidative and hydrolytic stability, evidenced by reduction of total polar material, free fatty acid and total oxidation value. Addition of palm stearin increased the slip melting point which improved the oil's oxidative stability but no significant increase in oil content of instant noodles was observed. Scanning electron microscopy and fluorescence microscopy showed the formation of larger pores in the noodle structure that facilitated oil retention.

CONCLUSION

Blending palm stearin into frying oil enhanced the frying stability and minimally affected the oil uptake in instant noodles. This article presents the viability of blending palm stearin into frying oils to develop longer-lasting frying oils. © 2024 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

The influences of street food vendor frying equipment on the quality of frying oil

This study was initiated to determine the quality of fresh and used oil for street vendor fried food products in Harar City, Ethiopia. Using a purposive sample technique, 12 respondents were selected for the study. The study obtained a total of 12 oil samples, categorized as fresh, in-use, and discarded, from two distinct groups of respondents. Specifically, six samples were collected from vendors utilizing an electric fryer constructed from stainless steel, while the remaining six samples were acquired from vendors employing a pan heated by wood or charcoal.The moisture content of fresh, in-use, and discarded oil samples, among other physical characteristics of the samples obtained from two types of vendors, was examined and found to vary between 0.14 and 0.44%, 0.19 and 0.52%, and 0.25 and 0.75%, respectively. Comparably, the refractive indices of oil samples that were fresh, in use, and discarded were 1.4595-1.4686, 1.4670-1.4885, and 1.4810-1.4960, in that order. Furthermore, the ranges of viscosities for fresh oil, oil samples in use, and oil samples that were discarded were 57.15-76.94, 100-196.50, and 210.22-288.50 mPa, respectively. Chemical properties, including % free fatty acid for similar samples, range from 0.22 to 1.30, 1.12 2.54, and 1.38-3.66%, respectively. Peroxide values of fresh, in-use, and discarded oil samples, have a maximum value of 11.19 meq/kg, 42.90, and 57.60 meq/kg, respectively. The iodine value showed the highest value for the fresh oil sample, while the minimum was obtained under discarded oil sample. The result indicated that they used low-quality oil. The values obtained after frying for samples collected from vendors who used a pan fryer heated with charcoal or wood fire deviated significantly from the requirements, indicating that the palm oil used by those street vendors was unsafe to consume because it could endanger the consumers' health.

Developing the procedure-enhanced model of ginger-infused sesame oil based on its flavor and functional properties

Ginger-infused sesame oil enriches the nutrition and provides enhanced flavor for the foods. An original processing procedure and module for evaluation were established in this study, using different raw materials (Guangdong and Chu ginger) and treatments (ginger powder, extract, and both). The quality, functionality, and flavor of the infused oils were evaluated. Ginger-infused sesame oil contained 0.58-3.22 µg/g of 6-gingerol, 0.21-0.88 µg/g of 6-shogaol. The number range of volatile compounds from 48 to 55 identified by gas chromatography-mass spectrometry varies depending on different process procedures. Agglomerative hierarchical clustering analysis revealed the flavor profiles were clustered by different varieties, while gingerol and phytosterol was by different treatments. In conclusion, sesame oil was an appropriate carrier for gingerol and phytosterol, which are characterized by higher antioxidant capacities (p < 0.05). These results show the benefits of developing infused oil products with enhanced functional and sensory properties.

Study by means of 1H nuclear magnetic resonance of the oxidation process in high oleic sunflower oil and palm oil during deep-frying of fish cakes

This study aimed to compare the frying performance of palm oil (PO) and high oleic sunflower oil (HOSO) during frying aquatic products. The quality change and frying performance of HOSO and PO during frying of fish cakes were investigated. The oxidation and hydrolysis products of both oils were explored by the nuclear magnetic resonance technique. The results showed that the color deepening rate of PO was higher than that of HOSO. After 18 h of frying, the total polar compound content of PO and HOSO reached 25.67% and 27.50%, respectively. HOSO had lower degree of oxidation than PO after 24 h of continuous frying. The polyunsaturated fatty acid content in HOSO and PO significantly decreased. The oleic acid content in HOSO remained above 80% during the frying process. The major aldehydes in both oils were (E, E)-2,4-alkadienals and n-alkanals and glycerol diesters (DAGs) were abundant in PO. Furthermore, the addition of fish cakes had slight effect on the quality of the frying oil. Therefore, HOSO is an appropriate candidate for frying owing to its excellent frying stability and nutritional value.

Understanding the Interaction between Nanomaterials Originated from High-Temperature Processed Starch/Myristic Acid and Human Monocyte Cells

High-temperature cooking approaches trigger many metabolically undesirable molecule formations, which pose health risks. As a result, nanomaterial formation has been observed while cooking and reported recently. At high temperatures, starch and myristic acid interact and lead to the creation of nanomaterials (cMS-NMs). We used a non-polar solvent chloroform to separate the nanomaterials using a liquid-liquid extraction technique. The physico-chemical characterization was carried out using dynamic light scattering (DLS), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), and Fourier-transform infrared spectroscopy (FTIR). To determine the biological impact of these nanomaterials using different in vitro assays, including a cell viability assay, microscopic staining, and gene expression analysis, we adopted the THP-1 cell line as an in vitro monocyte model in our study. The TEM images revealed that fabricated cMS nanomaterials are smaller than 100 nm in diameter. There were significant concerns found in the cytotoxicity assay and gene expression analysis. At concentrations of 100-250 µg/mL, the cMS-NMs caused up to 95% cell death. We found both necrosis and apoptosis in cMS-NMs treated THP-1 cells. In cMS-NMs-treated THP-1 cells, we found decreased expression levels in IL1B and NFKB1A genes and significant upregulation in MIF genes, suggesting a negative immune response. These findings strongly suggest that cMS-NMs originated from high-temperature food processing can cause adverse effects on biological systems. Therefore, charred materials in processed foods should be avoided in order to minimize the risk of health complications.

Oil Frying Processes and Alternative Flour Coatings: Physicochemical, Nutritional, and Sensory Parameters of Meat Products

The frying process changes can be desirable and undesirable, involving the physicochemical, nutritional, and sensory aspects, depending on the food and oil properties and the frying process. In this context, alternative flours emerge as a strategy for adding value to the food since they are rich in fiber, vitamins, and minerals, contributing to the variability of ingredients and the full use of food, including residues such as seeds and husks. This narrative review aims to gather current scientific data addressing the alternative flour coatings on breaded meat, mainly chicken, products to evaluate the effects on fried products' nutritional value, physicochemical parameters, and sensory attributes. Scopus, Science Direct, Springer, and Web of Science search bases were used. This review showed that alternative flours (from cereals, legumes, fruits, and vegetables) used as coatings increase water retention and reduce oil absorption during frying, increase fibers and micronutrient content, which are not present in sufficient quantities in commonly used flours due to the refining process. These flours also reduce gluten consumption by sensitive individuals in addition to favoring the development of desirable sensory characteristics to attract consumers. Therefore, frying processes in oil promote a reduction in humidity, an increase in oil absorption and energy content, and a decrease in vitamin content. In this context, coatings based on alternative flours can reduce these adverse effects of the frying process.

Study on the Frying Performance Evaluation of Refined Soybean Oil after PLC Enzymatic Degumming

It is known that phospholipase C (PLC) enzymatic degumming can hydrolyze phospholipids into diacylglycerol (DAG), which improves the efficiency of oil processing. However, it is unclear whether the presence of DAG and the use of enzymes affect the performance of the oil. This paper evaluated the frying performance of PLC-degummed refined soybean oil. Following the chicken wings and potato chips frying trials, results revealed that after 30 cycles of frying, free fatty acid (FFA) levels were 0.22% and 0.21%, with total polar compounds (TPC) at 23.75% and 24.00%, and peroxide value (PV) levels were 5.90 meq/kg and 6.45 meq/kg, respectively. Overall, PLC-degummed refined soybean oil showed almost the same frying properties as traditional water-degummed refined oil in terms of FFA, PV, TPC, polymer content, viscosity, color, foaming of frying oils, and appearance of foods. Moreover, FFA, TPC, polymer content, foaming, and color showed significant positive correlations with each other (p < 0.05) in soybean oil intermittent frying processing.

Tackling fat, oil, and grease (FOG) build-up in sewers: Insights into deposit formation and sustainable in-sewer management techniques

The increasing global demand for fatty products, population growth, and the expansion of food service establishments (FSEs) present significant challenges for the wastewater industry. This is often due to the build-up of fat, oil and grease (FOG) in sewers, which reduces capacity and leads to sanitary sewer overflows. It is crucial to develop economic and sustainable in-sewer FOG management techniques to minimise maintenance costs and service disruptions caused by the removal of FOG deposits from sewers. This study aims to understand the process of FOG deposit formation in both concrete and non-concrete sewers. Compared to fresh cooking oil, disposal of used cooking oil in households and FSE sinks results in the formation of highly adhesive and viscous FOG deposits. This occurs due to hydrolysis during frying, which increases the concentration of fatty acids, particularly palmitic acid, in the used cooking oil. Furthermore, metal ions from food waste, wastewater, and dishwashing detergents contribute to the saponification and aggregation reactions which cause FOG deposition in both concrete and non-concrete sewers. However, the leaching of Ca2+ ions exacerbates FOG deposition in cement-concrete sewers. The article concludes by suggesting future research perspectives and proposes implementation strategies for microbially induced concrete corrosion (MICC) control to manage FOG deposition in sewers. One such strategy involves applying superhydrophobic coating materials with low surface free energy and high surface roughness to the interior surfaces of the sewer. This approach would help repel wastewater carrying FOG deposit components, potentially disrupting the interaction between FOG components, and reducing the adhesion of FOG deposits to sewer surfaces.

How heated vegetable oil age? Effect of the container of heating on ageing

This study compares the ageing process of heated oil with unheated oil and assesses the effect of container used in heating on ageing. Four types of oils were heated on glass, copper and iron. The samples were allowed to age for 1 year. Unheated oils generally produce peroxide faster (for unheated maximum increase in 6-month is 2907 % from 1.351 to 40.627 but for heated maximum increase is 6574 % from 1.91 to 127.476). But they develop secondary oxidation products slowly (for unheated maximum increase in 6-month is 884 % from 1.553 to 15.29 but for heated maximum increase is 191 % from 6.42 to 18.72). For most oil heating in copper produce more p-anisidine value during ageing. The acid value of only unheated oils decreases between 6 months to 1 year. For the 1st six-month rate of increase in saponification value in unheated oil is much higher. The DPPH inhibition activity also changes differently.

Multivariate modelling analysis for prediction of glycidyl esters and 3-monochloropropane-1,2-diol (3-MCPD) formation in periodically heated palm oil

Palm oil is a vegetable oil that is widely used for cooking and deep-frying because of its affordability. However, repeatedly heated palm oil is also prone to oxidation due to its significant content of unsaturated fatty acids and other chemical toxicants such as glycidyl esters and 3-monochloropropane-1,2-diol (3-MCPD). Initially, the physicochemical properties such as colour, viscosity, peroxide, p-anisidine and total oxidation (TOTOX) of periodically heated palm oil were investigated. Chemical profiling and fingerprinting of six different brands of palm cooking oil during heating cycles between 90 and 360 min were conducted using Fourier transform infrared (FTIR) and 1H Nuclear Magnetic Resonance (NMR) metabolomics. In addition, the multivariate analysis was employed to evaluate the 1H NMR spectroscopic pattern of repeatedly heated palm oil with the corresponding physicochemical properties. The FTIR metabolomics showed significant different of the chemical fingerprinting subjected to heating duration, which in agreement with the result of 1H NMR metabolomics. Partial least squares (PLS) model revealed that most of the physicochemical properties of periodically heated palm oil are positively correlated (R2 values of 0.98-0.99) to their spectroscopic pattern. Based on the findings, the color of the oils darkened with increased heating time. The peroxide value (PV), p-anisidine value (p-AnV), and total oxidation (TOTOX) values increased significantly due to degradation of unsaturated compounds and oxidation products formed. We identified targeted metabolites (probable carcinogens) such as 3-monochloropropane-1,2-diol (3-MCPD) and glycidyl ester (GE), indicating the conversion of 3-MCPD to GE in repeatedly heated oils based on PCA and OPLSDA models. Our correlation analysis of NMR and physicochemical properties has shown that the conversion of 3-MCPD to GE was significantly increased from 180 to 360 min cooking time. The combination spectroscopic techniques with physicochemical properties are a reliable and robust methods to evaluate the characteristics, stability and chemical's structure changes of periodically heated palm oil, which may contribute to probable carcinogens development. This study has proven that combination of NMR and physicochemical analysis may predict the formation of the probable carcinogens of heated cooking oil over time which emphasizing the need to avoid certain heating cycles to mitigate formation of probable carcinogens during cooking process.

Tomato seed oil enriched mayonnaise: structural, rheological, and biochemical characterization

Two types of mayonnaise viz. eggless and egg based were prepared by substituting refined soybean oil by tomato seed oil (TSO) at varying concentrations (0-30%). Aim of the study was to utilise the potential of TSO in replaced of refined oil. With respect to oil particle distribution pattern in both types of mayonnaise, higher specific surface area (Dmean ~ 11.49 µm) and homogenous distribution of oil droplets was noted in egg-based mayonnaise. Rheological behavior depicted shear thinning properties in all types of mayonnaise with low viscosity (1.08 Pa s and 2.29 Pa s) being exhibited by tomato seed oil (TSO) incorporated mayonnaise. Nutritionally, significant increase of 65.5 and 26% in lycopene content while 29 and 34% increase in carotenoid content was noted upon incorporation of TSO in eggless and egg-based mayonnaise. Good storage and oxidative stability were demonstrated by TSO egg-based and eggless mayonnaise in terms of acid value and free fatty acids, also the peroxide value was also found lower than their respective control at the end of storage. Overall, tomato seed oil could be used as a non-conventional source of oil for such food applications owing to its close proximity with other vegetable oils and better nutritional profile like dominance of linoleic fatty acid i.e., 54.23% assayed via gas chromatography.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13197-023-05771-7.

Enhancement of Oxidative Stability of Deep-Fried Sunflower Oil by Addition of Essential Oil of Amomum villosum Lour

In this study, the essential oil of the fruits of Amomum villosum Lour. (AVEO) was extracted through steam distillation and the components of the AVEO were analyzed using Gas Chromatography-Mass Spectrometry (GC-MS). Additionally, the antioxidant capacity in vitro of the AVEO was gauged using radical scavenging activity (DPPH, ABTS, superoxide anion) and ferric ion reducing antioxidant power (FRAP) assays; the antioxidant effect of a certain concentration of AVEO is even comparable to 0.08 mg/mL of butylated hydroxytoluene (BHT). Moreover, AVEO was applied to sunflower oil in a 30 h successive deep-frying experiment. Throughout the frying procedure, the sunflower oil-added antioxidant showed different degrees of benign changes in the physical and chemical parameters compared to the blank group, with 1 g/kg of AVEO being more consistent with 0.01 g/kg of tert-butyl hydroquinone (TBHQ), while 1.5 g/kg of essential oil revealed a stronger antioxidative capability. Meanwhile, the organoleptic characteristics of Chinese Maye, including its appearance, taste, flavor, and overall acceptability, were ameliorated when AVEO was added at 1.5 g/kg. Consequently, AVEO can be applied to substitute synthetic antioxidants as a natural antioxidant and flavoring agent during the deep-frying course of food.

Optimizing extraction conditions and isolation of bound phenolic compounds from corn silk (Stigma maydis) and their antioxidant effects

During the processing of maize, Stigma maydis, also known as corn silk, is normally discarded as waste. Phytochemical research was carried out on the S. maydis to use it as a valuable source of bioactive components. This research aimed to maximize the recovery of free and bound phenolic compounds from corn silk under optimal experimental conditions. Response surface design was operated to optimize the alkaline hydrolysis extraction of bound phytochemicals from corn silk based on total phenolic content and DPPH radical scavenging activity. The optimum conditions (i.e., NaOH concentration 2 M, digestion time 135 min, digestion temperature of 37.5°C, the solid-to-solvent ratio of 1:17.5, and acetone) were obtained. The optimum parameters were used to extract the corn silk. The structures of two compounds isolated from ethyl acetate extracts were then identified as friedelin (1) and (E)-4-(4-hydroxy-3-methoxyphenyl) but-3-en-2-one (2). The DPPH, H₂ O₂ , and ABTS % inhibition of the compounds is as follows: compound (1) 74.81%, 76.8%, 70.33% and compound (2) 70.37%, 56.70% and 57.46%, respectively. The current study has opened previously unexplored perspectives of the composition of bound compounds in corn silk and established the foundations for more effective processing and utilization of corn waste. PRACTICAL APPLICATION: Bound phenolic compounds from corn silk under optimal experimental conditions were obtained. Corn silk can be utilized as a type of medicinal herb as well as a source of inexpensive natural antioxidants.

Antioxidant activity of selected plants extract for palm oil stability via accelerated and deep frying study

Antioxidants are organic compounds that help to prevent lipid oxidation and improve the shelf-life of edible oils and fats. Currently, synthetic antioxidants were used as oil stabilizing agent. However, synthetic antioxidants have been causing various health risks. As a result, natural antioxidants such as most parts of olive plant, green tea, sesame, medicinal plants were plays an important role to retard lipid oxidation. The palm oil was continuously frying at 180 °C for 6 days using Lepidium sativum (0.2%w/v) and Aframomum corrorima (0.3%w/v) seeds extracts as antioxidant. The physicochemical properties of oil in the herbal extract additive group significantly maintained the oil quality during frying compared to the normal control and the food sample containing group. The L. sativum extract had a greater oil stability compared to A. corrorima extract. However, the frying oil without herbal extract significantly increase the physicochemical properties of oil such as iodine value, acid value, free fatty acid, total polar compounds, density, moisture content, pH etc. during repetitive frying. The antioxidant activity of the plant extract was outstanding, with an IC₅₀ value in the range of 75-149.9 μg/mL when compared to the standard butyl hydroxy anisole, which had an IC₅₀ value in the range of 74.9 ± 0.06-96.7 ± 0.75 μg/mL. The total phenolic and flavonoid content of the extract for L. sativum was 128.6 ± 0.00 mg GAE/g, 127.0 ± 0.00 mg QE/g, and 130.16 ± 0.001 mg GAE/g, 105.76 ± 0.02 mg QE/g, respectively. The significant effect of the plant extract on the degradation of oil and the formation of free fatty acids was confirmed by Fourier transform infrared spectroscopy. The result of these study revealed that the ethanolic crude extract of L. sativum and A. corrorima had a potential natural antioxidant to prevent the degradation of palm oil.

Improving rhamnolipids production using fermentation-foam fractionation coupling system: cell immobilization and waste frying oil emulsion

This work focused on the development of an inexpensive carbon source and the improvement of the fermentation-foam fractionation coupling system. The rhamnolipids production capacity of waste frying oil (WFO) was evaluated. The suitable bacterial cultivation of seed liquid and the addition amount of WFO was 16 h and 2% (v/v), respectively. A combined strategy of cell immobilization and oil emulsion avoid cell entrainment inside foam and improves the oil mass transfer rate. The immobilization conditions of bacterial cells into alginate-chitosan-alginate (ACA) microcapsules were optimized using the response surface method (RSM). Under the optimal conditions, rhamnolipids production using batch fermentation with immobilized strain reached 7.18 ± 0.23% g/L. WFO was emulsified into a fermentation medium using rhamnolipids as emulsifier (0.5 g/L). By monitoring dissolved oxygen, 30 mL/min was selected as a suitable air volumetric flow rate for fermentation-foam fractionation coupling operation. The total production and recovery percentage of rhamnolipids were 11.29 ± 0.36 g/L and 95.62 ± 0.38%, respectively.

The synergistic effect of waste cooking oil and endod (Phytolacca dodecandra) on the production of high-grade laundry soap

A green viewpoint based on the production of soap using waste products such waste cooking oils (WCOs) and Endod (Phytolacca dodecandra) is presented. The process of saponification, which involves reacting triglycerides with fats and oils in an alkaline solution, produces soap. With the help of WCO and Endod as manufacturing inputs, this study intends to create high-quality, commercially viable eco-friendly soaps. The optimal blend of WCO and Endod with sodium hydroxide solution was used in the current investigation to create laundry soaps. Evaluations were done on the cleansing effects and physico-chemical makeup of prepared soap. As a reference control, the raw oil soaps made without and with frying were employed. The free caustic alkali content, chloride content, moisture content, ethanol-insoluble-matter, total fatty matter, pH, and foam height values of the prepared soap were found to be in the range of 0%, 0%, 16.56-22.52%, 0.1-3.05%, 63.41-75.46%, 9.22-9.82%, and 3.3-8.1 cm respectively. The results obtained by blending fried WCOs and Endod were comparable to the Physico-chemical properties of the Endod-free uncooked/fresh oil soap. The soap made by blending WCO and Endod has higher cleansing power and better lather formation than the prepared soap with WCO without Endod. Moreover, the observed data are comparable with similar data reported in other literature, recommended acceptable standards (EAS, CES), and from many countries including the British, Malaysia, and the Philippines. Cooking oils fried at different temperatures do not have much effect on the quality of soap making. This suggested that the blending of WCOs and Endod can be used as raw materials to prepare high-quality and economically feasible soaps by replacing imported oils and fats.

Formation, migration, derivation, and generation mechanism of polycyclic aromatic hydrocarbons during frying

Polycyclic aromatic hydrocarbons (PAHs) are carcinogenic and lipophilic, which can be found in frying system. This review summarized the formation, migration and derivation for PAHs, hypothesized the possible mechanism for PAHs generation during frying and presented the research prospects. Some factors like high oil consumption, high temperature, long time and oil rich in unsaturated fatty acids promoted the formation of PAHs and the presence of antioxidants inhibited the PAHs formation. The effect of proteins and carbohydrates in foods on the formation of PAHs is inconclusive. The formed PAHs were migrated into food and air. Moreover, some PAHs transformed into more toxic PAHs-derivatives during frying. The generation of PAHs may be related to low-barrier free radical-mediated reaction and the unsaturated hydrocarbons may be precursors of PAHs during frying. In future, the isotope tracer technology and on-line detection may be applied to discover intermediates and provide clues for studying PAHs generation mechanisms.

Olive Oil Benefits from Sesame Oil Blending While Extra Virgin Olive Oil Resists Oxidation during Deep Frying

Fresh potatoes were deep-fried in olive oil (OO), extra virgin olive oil (EVOO), and their blends with 5%, 10%, and 20% v/v sesame oil (SO). This is the first report on the use of sesame oil as a natural source of antioxidants during olive oil deep frying. The oil was evaluated for anisidine value (AV), free fatty acids (FFAs), extinction coefficient (K₂₃₂ and K₂₇₀), Trolox equivalent antioxidant capacity (TEAC), and total phenols (TPs) until the total polar compounds (TPCs) reached 25%. Sesame lignan transformations were monitored through reversed-phase HPLC. While the TPCs in olive oils increased at a steady rate, the addition of 5%, 10%, and 20% v/v SO delayed TPCs' formation for 1, 2, and 3 h, respectively. The addition of 5%, 10%, and 20% v/v SO increased the olive oil frying time by 1.5 h, 3.5 h, and 2.5 h, respectively. The addition of SO to OO reduced the secondary oxidation products' formation rate. The AV for EVOO was lower than OO and all tested blends, even those with EVOO. EVOO was more resistant to oxidation than OO, as measured by the TPCs and TEAC, while the frying time rose from 21.5 to 25.25 h when EVOO replaced OO. The increase in frying time for OO but not for EVOO, after SO addition, points to a niche market for EVOO in deep frying.

A comprehensive review on nanocatalysts and nanobiocatalysts for biodiesel production in Indonesia, Malaysia, Brazil and USA

Biodiesel is an alternative to fossil-derived diesel with similar properties and several environmental benefits. Biodiesel production using conventional catalysts such as homogeneous, heterogeneous, or enzymatic catalysts faces a problem regarding catalysts deactivation after repeated reaction cycles. Heterogeneous nanocatalysts and nanobiocatalysts (enzymes) have shown better advantages due to higher activity, recyclability, larger surface area, and improved active sites. Despite a large number of studies on this subject, there are still challenges regarding its stability, recyclability, and scale-up processes for biodiesel production. Therefore, the purpose of this study is to review current modifications and role of nanocatalysts and nanobiocatalysts and also to observe effect of various parameters on biodiesel production. Nanocatalysts and nanobiocatalysts demonstrate long-term stability due to strong Brønsted-Lewis acidity, larger active spots and better accessibility leading to enhancethe biodiesel production. Incorporation of metal supporting positively contributes to shorten the reaction time and enhance the longer reusability. Furthermore, proper operating parameters play a vital role to optimize the biodiesel productivity in the commercial scale process due to higher conversion, yield and selectivity with the lower process cost. This article also analyses the relationship between different types of feedstocks towards the quality and quantity of biodiesel production. Crude palm oil is convinced as the most prospective and promising feedstock due to massive production, low cost, and easily available. It also evaluates key factors and technologies for biodiesel production in Indonesia, Malaysia, Brazil, and the USA as the biggest biodiesel production supply.

An investigation on glutathione derived from spinach and red cabbage leaves and their effects of adding to meat patties

Plants that produce leaves have been cultivated by humans for thousands of years because of the benefits they provide in terms of food and other necessities. Because of their high nutritional value and key phyto-components like glutathione, Leaf producing vegetables (LPVs) are being studied for their potential uses and health benefits. As a result, the focus of this study was using efficient methods for isolating and identifying glutathione from spinach and red cabbage. Glutathione was extracted using three extraction solvents: water (100%), ethanol (100%), and a combination of ethanol and water (30% and 70%, respectively) by volume (v/v), while separation was accomplished using ultrafiltration equipment. In our investigation, the best extraction solvent was a mixture of ethanol and water at a ratio of 30:70% (v/v), which extracted 951 µg/g glutathione. The antioxidant activity of plant leaf extract was measured using DPPH, with butylated hydroxytoluene serving as a comparative standard. Identification and characterization of glutathione from plant leaf extracts were revealed by thin-layer chromatography (TLC), ultraviolet-visible (UV-Vis) spectrophotometry studies, Fourier transform infrared (FTIR) spectroscopy, and high-performance liquid chromatography (HPLC). In addition, the physical and chemical properties (pH, water holding capacity, extracted liquid volume, peroxide value, free fatty acids, and thiobarbituric acid) of meat patties prepared with three different concentrations of determined glutathione were tested for susceptibility to preservation during 10 days of refrigeration at 4 ± 1 °C. The findings of the current study provide vast prospects for subsequent research to researchers and scientists that the glutathione obtained from leaf extract has no toxicity that might be applied to developed functional foods and other food formulations. Because foods containing plant-derived glutathione improve health, biological function, and food spoilage. It may be utilized as high-quality antioxidants that are safe and non-toxic. Furthermore, glutathione preserves food quality and prevents oxidation.

A comparative study of chemical constituents and safety of Thai herbal medicated oil formula and traditional medicated oil

OBJECTIVES

Medicated oil has been traditionally used as an analgesic medicine to relieve pain by applying to the skin over painful muscles, and has been established in The National List of Essential Medicines (2556 B.E.). Traditional Medicated oil (TMO) consists of cassumunar ginger, Wan En Lueang, and Wan Ron Thong. It is prepared by frying herbs in coconut oil which is a traditional method. Thai Herbal Medicated oil formula (MOF) comprises cassumunar ginger, sweet flag, lesser galangal, wild turmeric, Wan En Lueang, and Wan Ron Thong. Its preparation by maceration with methyl salicylate is modified method to avoid the heat in the traditional preparation. Since both recipes have different methods of extraction and compositions, it is necessary to determine the chemical constituents and acute skin irritation potential of MOF and TMO.

METHODS

This study applied Gas Chromatography-Mass Spectrometry (GC-MS) for quality assessment of MOF extract and TMO extract. The mass spectra of the compounds matched with authentic standards from the NIST library. The compounds were identified by comparing their retention time and peak area, and the percentage of matched factor was more than 80%. The safety assessment on acute skin irritation used the 4 h human patch test (4 h HPT) in 36 healthy subjects.

RESULTS

The 37 compounds were found in MOF extract. The most common chemical constituents were terpene derivatives; monoterpenes and sesquiterpenes, and others, namely benzene derivatives, ester, phenylpropanoid, and other compounds. The 33 compounds were found in TMO extract and the chemical groups were similar to MOF extract. The 4 h HPT demonstrated that the MOF extract, TMO extract, methyl salicylate solvent, and coconut oil solvent, did not induce skin irritation. However, the vehicle of the formulae and the whole formulae as MOF and TMO clinically induced skin irritation and accorded with rubefacient. The characteristic as mild erythema or dryness, but not erythema with edema, could appear after the use of rubbing skin products.

CONCLUSIONS

The chemical constituents found in MOF and TMO extracts were partially different and their acute skin irritation reactions were not significantly different. A study on the efficacy of both remedies should be performed in the future, as well as a study on active chemical constituents. This study provides scientific evidences of quality and safety, including GC-MS condition for poly-herbal medicated oil standardization.

Characterization of physical properties, volatile compounds and aroma profiles of different salted egg yolk lipids

Salted egg yolks (SEY) have a desirable and unique flavor with multiple underlying applications in food processing, and their abundant lipids contribute to a creamy and pleasant aroma. However, it is important to maintain the stability of the SEY flavor, which depends to a large extent on the egg species and the processing method. This study aimed to extract different SEY lipids with conventional solvents, analyze the fatty acid composition, and screen the volatile compounds to elucidate the flavor differences between salted hen eggs and duck eggs. Compared to ethanol extraction, acetone-extracted lipids had lower acid value and viscosity, and almost had no phospholipid content. Fatty acid analysis revealed that the highest content of fatty acid in SEY lipids was oleic acid, followed by palmitic acid and linoleic acid, while there were significant variations of different SEY lipids in the fatty acid profiles. The volatile compounds were identified by headspace solid-phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS), and the overall odor was detected by the electronic nose (E-nose). A total of 27 volatile compounds were analyzed in SEY lipids and divided into 8 chemical classes. The aldehydes, furans and pyrazines were decreased, and the hydrocarbons were increased compared with untreated SEY. The combination of the physical properties and flavor evaluation of SEY lipids could provide a theoretical basis for the extension of the characteristic flavor matrix in SEY.

Effects of High-Canolol Phenolic Extracts on Fragrant Rapeseed Oil Quality and Flavor Compounds during Frying

Fragrant rapeseed oil (FRO) is a frying oil widely loved by consumers, but its quality deteriorates with increasing frying time. In this study, the effect of high-canolol phenolic extracts (HCP) on the physicochemical properties and flavor of FRO during frying was investigated. During frying, HCP significantly inhibited the increase in peroxide, acid, p-anisidine, and carbonyl values, as well as total polar compounds and degradation of unsaturated fatty acids. A total of 16 volatile flavor compounds that significantly contributed to the overall flavor of FRO were identified. HCP was effective in reducing the generation of off-flavors (hexanoic acid, nonanoic acid, etc.) and increased the level of pleasant deep-fried flavors (such as (E,E)-2,4-decadienal). Therefore, the application of HCP has a positive effect on protecting the quality and prolonging the usability of FRO.

Investigation of used cooking oil on the formation of FOG deposits in sewer line clogging

Fat, oil, and grease (FOG) deposits, resulting from saponification reaction, have been identified as the primary source of blockage of sewer pipes. This mainly emanates from the adhesion of these deposits on pipe walls, culminating in the sanitary sewer overflows (SSOs). This undesired phenomenon poses several challenges for municipalities, including environmental issues, health-related hazards, and an increase in incurred costs. Unlike the previous literature, the present study, for the first time, attempts to characterize the effect of used cooking oils (a mixture of different oils) as a perceived crux, triggering the genesis of deposits. The experimental results revealed that there exists a host of physical and chemical disparities between fresh oil calcium soaps (FOCSs) and used oil calcium soaps (UOCSs). Notably, when mixed with water, FOCSs produced non-miscible layers, whereas a homogenous, sticky, and viscous solution observed for UOCSs. Fourier transform infrared (FTIR) analysis casts light on the fact that the heating process would greatly influence the oil chemical structure and its resultant calcium soaps. In comparison with calcium chloride, as time elapsed, the optical microscope images illustrated that the calcium sulfate clots formation proceeded at an accelerated rate, delivering particles with larger sizes. Viscosity and adhesion are two prominent distinctions between soaps. In sharp contrast to soap produced from oil with a higher palmitic acid content, it was discerned that the oil containing less palmitic acid generates UOCSs with higher viscosity and adhesion than FOCSs. It can therefore be inferred that the distinct chemical structures driven by high temperature during the cooking process produce soaps with different characteristics as compared with fresh oil. This phenomenon would have a profound impact on the formation of the deposits in sewer lines.

A Comparison of the Stability of Refined Edible Vegetable Oils under Frying Conditions: Multivariate Fingerprinting Approach

The stability of highly consumed vegetable refined oils after discontinuous frying of potatoes was compared. Both those vegetable oils containing additives and those that did not were considered. Vegetable oil samples were evaluated using refractive index, anisidine and peroxide values, UV absorbance and dielectric constant-based determination of the content of total polar compounds. Chemical changes caused over the frying time were monitored and multivariate modelling of the data was carried out. A new gas chromatographic-mass spectroscopy method was intended to record a fingerprint of both polar and non-polar compound fractions. Multivariate models of chromatographic fingerprints were also developed, and the results obtained from both approaches were verified to be statistically similar. In addition, multivariate modelling also allows to differentiate among vegetable oils according to oxidation performance. Indeed, it was initially observed that olive oils presented the highest natural thermo-oxidative stability compared to other seed oils, although it should be noted that these differences were not significant when regarding olive pomace oils and seed oils containing synthetic additives.

Utilization of Sunflower Oil-based Oleogel forDeep-Fried Coated Chicken Products

This study aimed to examine the effect of using oleogel as a frying medium on the quality of coated and deep-fried chicken products. Sunflower oil-based oleogels prepared with 0.5%, 1%, 1.5% and 2% carnauba wax were produced for deep frying of coated chicken products and were compared to sunflower and commercial frying oil based on palm oil. The increased carnauba wax concentration in the oleogel decreased the pH, oil, oil absorbance and TBARS value of coated chicken (p < 0.05). Samples deepfried with oleogels containing 1.5% and 2% carnauba wax had the lowest pH values. In addition, since the oil absorption during deep-frying was significantly reduced in these groups (1.5 and 2%), the fat contents of coated products were also lower (p < 0.05). The use of oleogel as a frying medium did not cause a significant change in the color values of the coated chicken products. However, the increased carnauba wax concentration in the oleogel increased the hardness of coated chicken (p < 0.05). As a result, sunflower oilbased oleogels with a carnauba wax content of 1.5% and higher which is healthier in terms of saturated fat content can be used as frying media and can be improved the quality of coated and deep-fried chicken products.

Quality Change in Camellia Oil during Intermittent Frying

Camellia oil with a high oleic acid content is widely used for frying. To comprehensively describe the quality change in camellia oil during frying, the changes in composition, deterioration indicators, and volatile profiles were investigated. The results showed that tocopherols mainly degraded in the early stage of frying, followed by unsaturated fatty acids (UFA). This caused the carbonyl value and total polar compounds level to significantly increase. Moreover, frying promoted the accumulation of volatile compounds in terms of type and abundance, especially aldehydes, which are related to the degradation of UFA. Principal component analysis showed that the frying of camellia oil was divided into three stages. First, the camellia oil with a heating time of 2.5-7.5 h showed excellent quality, where tocopherol played a major role in preventing the loss of UFA and was in the degradation acceleration stage. Subsequently, as tocopherol entered the degradation deceleration stage, the quality of camellia oil heated for 10.0-15.0 h presented a transition from good to deteriorated. Finally, tocopherol entered the degradation stagnation stage, and the quality of camellia oil heated for 17.5-25.0 h gradually deteriorated, accompanied by a high level of volatile compounds and deterioration indicators. Overall, this work comprehensively determined the deterioration of camellia oil during intermittent frying and offered valuable insights for its quality evaluation.

Thermally oxidized sunflower oil diet alters leptin/ghrelin balance and lipid profile in rats: Possible role of reactive aldehydes in dyslipidemia

Sunflower oil is a common edible oil in the world, which is highly prone to oxidative degradation during the frying process. The present study aimed to investigate the effects of products obtained from the thermal oxidation process of sunflower oil on metabolic indices, and the secretion status of leptin and ghrelin in rats. In vivo studies were designed after determining the rate of formation of active aldehydes and peroxide value in sunflower oil following 300°C in a period of 30-240 min. To this end, 36 rats in 6 separate groups were fed with 2 ml of normal saline, fresh sunflower oil, and heated oils at 30, 60, 120, and 240 min for 45 days. Finally, lipid profile changes and leptin/ghrelin secretion were examined, along with histological changes in the liver tissue. The results indicated a significant increase in serum LDL, VLDL and triglycerides, and a decrease in HDL, in the groups treated with heated oils. These changes were associated with a higher accumulation of triglycerides, active aldehydes, and histological changes in the hepatic tissue. Although the serum ghrelin level in the groups receiving heated oil did not change significantly compared to the fresh oil, the serum leptin level increased significantly in the groups receiving heated oil. According to our findings, increasing the time of sunflower oil heating enhanced the formation of active aldehydes, so that daily consumption of such oxidized oils might be associated with the occurrence of dyslipidemia, fatty liver and the development of leptin resistance. PRACTICAL APPLICATIONS: Sunflower oil is highly prone to oxidative degradation during the frying process. Increasing time of sunflower oil heating enhanced the formation of active aldehydes. Daily consumption of oxidized oils might be associated with the occurrence of dyslipidemia, fatty liver and the development of leptin resistance.

Possibility of using low-field nuclear magnetic resonance (LF-NMR) and differential scanning calorimetry (DSC) to monitor frying oil degradation

In this work, chemical degradation of oil was determined as a function of frying time during intermittent deep-fat frying (i.e. 185 °C for 5 h per day for 12 days) and was correlated with the thermal characteristics as measured by Differential Scanning Calorimetry (DSC) and proton mobility by Low-Field Nuclear Magnetic Resonance (LF-NMR). Linear increases of FFAs and PV were observed as a function of frying time. FFAs and PV were strongly correlated with the melting enthalpy. The melting enthalpy of oil decreased exponentially, and the melting temperature remained nearly same until 30 h of frying time followed by a sharp increase. The relaxation times of rigid, semi-rigid and mobile protons (i.e. T 2b , T 21 , and T 22 ) decreased with the increase of frying time. The decrease of T 21 , and T 22 were steeper as compared to the T2b. A strong correlation was observed between conventional chemical parameters (i.e. PV and FFAs), and T 21 and T 22. The populations of the three pools of protons as identified by Inverse Laplace Transformation and Gaussian distribution function showed the interchange of the protons with the chemical changes during frying. It is concluded that chemical free DSC and LF-NMR could be potential methods to monitor frying oil degradation.

Lignocellulosic Biomasses from Agricultural Wastes Improved the Quality and Physicochemical Properties of Frying Oils

In this work, the effects of using natural lignocellulosic-based adsorbents from sugarcane bagasse (SC), cornstalk piths (CP), and corn cob (CC) on the physicochemical properties and quality of fried oils were studied. The properties of lignocellulosic biomasses were examined using X-ray diffraction (XRD), scanning electron microscope (SEM), and Fourier transform infrared spectroscopy (FTIR). Moreover, the changes in the physicochemical properties of fresh, fried oils (for 4, 8, 12, 16 and 20 h) and adsorbents-treated oils were examined. The XRD results revealed that SC and CP biomasses have more amorphous regions than CC biomass, which had the highest crystallinity percentage. The results also showed that lignocellulosic biomasses enhanced the quality of the used oils. SC was the most effective biomass to enhance the properties of the used sunflower oil. For instance, the acid value of oil samples fried for 20 h reduced from 0.63 ± 0.02 to 0.51 ± 0.02 mg KOH/g oil after SC biomass treatment. For the peroxide value, the SC biomass treatment reduced it from 9.45 ± 0.56 (fried oil for 20 h) to 6.91 ± 0.12 meq O₂/kg. Similarly, SC biomass adsorbent reduced the p-Anisidine Value (p-AV) of the used oil (20 h) from 98.45 ± 6.31 to 77.92 ± 3.65. Moreover, SC adsorbents slightly improved the lightness of the used oils (20 h). In conclusion, natural lignocellulosic biomasses, particularly SC, could be utilized as natural adsorbents to improve the oil quality. The results obtained from this study could help in developing sustainable methods to regenerate used oils using natural and cheap adsorbents.

Comparative Studies on the Physicochemical and Volatile Flavour Properties of Traditional Deep Fried and Circulating-Air Fried Hairtail (Trichiurus lepturus)

The aim of this study is to investigate the effects of deep frying (DF) and air frying (AF) on the quality and flavour profile of hairtail (Trichiurus lepturus) fillets. The changes of some physicochemical indices such as moisture content, oil content, colour, thiobarbituric acid reactive substances (TBARS) and peroxide values (POV) in hairtail fillets were detected with increasing frying time. According to these physicochemical indices and sensory evaluation, deep frying for 7 min under 190 °C (DF7) and air frying for 24 min under 190 °C (AF24) were selected as samples for their great quality. The flavour fingerprint of hairtail (Raw, DF7, AF24) was developed and volatile compounds were investigated by HS-GC-IMS. A total of 28 volatile substances including aldehydes, alcohols, ketones and others were identified both in the DF7 and AF24 samples. There are differences in the aroma fingerprint between the DF7 and AF24 samples. DF was characterised by 2-Heptanone, (E)-2-Heptenal, 2-Pentyfuran and 1-Pentanol, AF was characterised by 2-methylbutanol, Ethyl methyl ketone-M and 3-hydroxy-2-butanone. These findings suggest that the aroma of hairtail fillets after DF7 and AF24 was significantly different and supply flavour information and practical applications of the fried hairtail fillets.

Separated from the Essential Oil of Coriandrum sativum L. Leaves, Carvacrol and Limonene Showed Antioxidant Effects in Sunflower Oil under Frying Conditions

The frying process, a popular cooking technique, is widely used in the food industry around the world for the production of fried foods. Nevertheless, it is always accompanied by potential challenges including lipid peroxidation of vegetable oils. In this study, the influence of the coriander leaves essential oil (CLEO) on the oxidative stability of sunflower oil under frying conditions and the sensory attributes of fried food (Chinese Mahua) during the sensory evaluation were investigated. The results indicated that compared with the control, CLEO at 0.12 g/kg could obviously suppress the increases for the total polar compounds (TPC), thiobarbituric acid (TBA), color, conjugated dienes (CD), conjugated trienes (CT) and viscosity of sunflower oil, and prominently restrain the oxidization procedure of unsaturated fatty acid (UFA). Meanwhile, the decline in the sensory attributes for the Chinese Mahua was significantly inhibited. Furthermore, the study revealed the antioxidant effect of CLEO was mainly attributed to two compounds, carvacrol and limonene, which were separated by the bioassay-guided fractionation. Consequently, CLEO and the two compounds may be employed as potential natural antioxidants to improve the oxidation stability of sunflower oil under frying conditions.

A novel GAN-based regression model for predicting frying oil deterioration

Frying is a common food processing method because fried food is popular with consumers for its attractive colour and crisp taste. What's concerning is that the complex physical and chemical reactions occurring during deep frying are harmful to the well-being of people. For this reason, researchers proposed various detecting methods to assess frying oil deterioration. Some studies design sensor probe, others utilize spectroscopic related methods. However, these methods all need the participating of professionals and expensive instruments. Some of the methods can only function on a fixed temperature. To fix the defects of the above models, in this study, we make use of recent advances in machine learning, specifically generative adversarial networks (GAN). We propose a GAN-based regression model to predict frying oil deterioration. First, we conduct deep frying experiments and record the values of indexes we choose under different temperature and frying time. After collecting the data, we build a GAN-based regression model and train it on the dataset. Finally, we test our model on the test set and analyze the experimental results. Our results suggest that the proposed model can predict frying oil deterioration without experiments. Our model can be applied to other regression problems in various research areas, including price forecasting, trend analysis and so on.

Comparative analysis of aroma compounds in French fries and palm oil at three crucial stages by GC/MS-olfactometry, odor activity values, and aroma recombination

BACKGROUND

Flavor is a key element affecting the popularity of French fries (FFs). When oil is heated, the changes in oil quality can affect the flavor of the food directly.

RESULTS

The flavor of FFs showed three crucial stages: the break-in (3.0% to 6.8% of total polar compounds (TPC)), optimum (7.0% to 19% of TPC), and degrading (above 19.5% of TPC) stages. To distinguish the key aroma compounds in the three stages, the FFs, prepared in palm oil (PO) at TPC of 3.0% (FF3), 7.5% (FF8), 19.5% (FF20), and their relevant oils (PO3, PO8, PO20), were selected for molecular sensory science analysis. The results indicated that the concentration of (E, E)-2,4-decadienal linked with the deep-fried odor was low in FF3, which led to a lower sensory score in the FF3 sample. The FF8 sample had a high (E, E)-2,4-decadienal content and received a high sensory score. The FF20 sample possessed high hexanoic acid, heptanoic acid (sweaty odor), benzaldehyde (stale odor), octanoic acid (sweaty odor), (E)-2-undecenal (fatty odor), and trans-4,5-epoxy-(E)-2-decenal (metallic odor) content, thus leading to FFs having an undesirable flavor and PO20 showed high hexanoic acid and heptanoic acid content, contributing to a lower sensory score in PO20.

CONCLUSION

The FFs' flavor became undesirable when TPC was above 19.5% due to significant influences of some off-flavor compounds. It is therefore essential to prevent the generation of rancid substances to prolong the optimum stage during frying. © 2021 Society of Chemical Industry.

Differences in flavor characteristics of frozen surimi products reheated by microwave, water boiling, steaming, and frying

This study investigated the effects of different reheating methods (microwave, water boiling, steaming, and frying) on the flavor of surimi gels with untreated sample as control. Electronic nose and electronic tongue results showed that microwave could better maintain the original odor and taste characteristics of surimi gels. Additionally, 43 kinds of volatile aroma compounds were detected in surimi gels, including aldehydes, alcohols, ketones, heterocycles, and esters. The aroma fingerprints of surimi gels were similar between water boiling and steaming and between microwave and the control, whereas frying showed the most unique aroma profile possibly related to the highest TBARS values. The total contents of nucleotides, carnosine and lactic acid were significantly higher in fried samples relative to other samples. In conclusion, all the reheating treatments can alter the flavor of samples, but microwave showed better performance in sensory evaluation and maintaining the original flavor of surimi gels.

Evaluation of the Effect of Hydromethanolic Seed Extract of Lepidium sativum L. (Fetto) on Deep-fried Palm Oil Diet Induced Nonalcoholic Fatty Liver Disease on Male Swiss Albino Mice

Introduction

Nonalcoholic fatty liver disease (NAFLD) is the most prevalent disease due to a dramatic change in dietary habits, especially an increase in consumption of fat and carbohydrates in deep-fried foods.

Objective

The objective was to evaluate the effect of hydromethanolic seed extract of Lepidium sativum on deep-fried palm oil diet induced NAFLDon male mice.

Methods

An experimental study design was conducted. Twenty-four male mice aged 8 to 10 weeks, weighing 32–42 g were divided into four groups. The four groups were divided into two controls and two treatments. Mice in normal control (C₀) were administered only with the basal diet whereas negative control (C₁) provided only with the deep-fried palm oil diet. The treatment groups T_1, and T₂ were administered with deep-fried palm oil diet and HMSELS at dose of 200 and 400 mg/kg/day, respectively for 28 days. Then on day 29, the mice were fasted overnight, anaesthetized and sacrificed by cervical dislocation after blood was taken by cardiac puncture for liver function tests while liver tissues were taken for histopathology investigation.

Results

The serum ALT and total bilirubin showed significant decrement whereas the serum albumin levels showed significant increment in T₂ group. However, serum AST and ALP levels were decreased significantly in both T₁ and T₂ groups. Besides, the T₂ group liver sections of mice were showed better effect of HMSELS on restoring the damaged liver histopathology almost toward normal.

Conclusion

The HMSELS at a dose of 400 mg/kg/day (T₂) was more effective on the liver function tests and liver histopathology that altered by feeding deep-fried palm oil diet. The good protective effect of HMSELS against deep-fried palm oil diet-induced NAFLD might be due to its antioxidant content.