Changes in the volatile profile, fatty acid composition and other markers of lipid oxidation of six different vegetable oils during short-term deep-frying

Accelerating the oxidation of pork fat by illumination and fat oil for the production of Baijiu beverage

BACKGROUND

Aged pork fat, deeply oxidized pork fat soaked in basic liquor for more than half a year, is an important material in producing Chi-aroma Baijiu (CAB). With the expansion of production scale of CAB, innovative strategies for efficient production of aged pork fat are in great demand. The purpose of this study is to accelerate the lipid oxidation of pork fat and improve the productivity of aged pork fat.

RESULTS

Results showed that polyunsaturated fatty acids (PUFAs) were the main reactant; generation reactions of lipid peroxides and free fatty acids (FFAs) were two limiting steps during the preparation of aged pork fat. Processing under illumination could alleviate the first limiting step by increasing the peroxide value and p-anisidine value of pork fat to 16.22- and 28.48-fold higher than control samples and simultaneously the PUFAs were increased to 190.60 ± 0.19 g kg^-1 . Soaking in basic liquor with deeply oxidized fat oil could alleviate the second limiting step by transferring FFAs from fat oil into pork fat. With more oxidized PUFAs, the acid value of the pork fat was 7.91-fold higher than that of the control.

CONCLUSION

Illumination and deeply oxidized fat oil could alleviate the two rate-limiting steps of lipid oxidation and improve the productivity of aged pork fat significantly. The results are highly applicable in the CAB industry. © 2020 Society of Chemical Industry.

Gels as fat replacers in bakery products: a review

Several strategies have been studied to replace or decrease fat content in bakery products aiming improving their nutritional profile. This paper reviewed the effect of different vehiculization systems (hydrogels, emulgels and oleogels) as fat replacers in different types of bakery goods, focusing on technological and nutritional properties of the reformulated products. The most commonly used fat source for replacement purposes were vegetable oils with high monounsaturated fatty acid content, such as olive oil and canola oil (44% of the revised papers used them), whereas high polyunsaturated fatty acid content oils were used in 34% of papers. Oleogelation was the most frequent used method of oil structuring, using waxes and fibers as stabilizers. Reductions of total fat between 19% and 46% and saturated fatty acid between 33% and 87% were achieved, enough to reach the minimum legal limit to state nutrition claims, under the EU legislation, on several products. Sensory evaluation results showed that partially replaced products (<75% replacement) were more appreciated by panelists than fully replaced ones. This review highlights the wide range of alternatives within gel-like fat replacers, that have potential to be applied in different bakery products and the challenge to produce nutritionally enhanced foods and technologically and sensory acceptable.

Identification of the Olfactory Profile of Rapeseed Oil as a Function of Heating Time and Ratio of Volume and Surface Area of Contact with Oxygen Using an Electronic Nose

The process of deep fat frying is the most common technological procedure applied to rapeseed oil. During heat treatment, oil loses its nutritional properties and its original consumer quality is lowered, which is often impossible to determine by organoleptic assessment. Therefore, the aim of the study was to correlate markers of the loss of the nutritional properties by rapeseed oil related to the frying time and the surface area of contact with oxygen with changes in the profile of volatile compounds. The investigations involved the process of 6-, 12-, and 18-h heating of oil with a surface-to-volume ratio (s/v ratio) of 0.378 cm⁻¹, 0.189 cm⁻¹, and 0.126 cm⁻¹. Samples were analysed to determine changes in the content of polar compounds, colour, fatty acid composition, iodine value, and total chromanol content. The results were correlated with the emission of volatile compounds determined using gas chromatography and an electronic nose. The results clearly show a positive correlation between the qualitative degradation of the oil induced by prolonged heating and the response of the electronic nose to these changes. The three volumes, the maximum reaction of the metal oxide semiconductor chemoresistors, and the content of polar compounds increased along the extended frying time.

Analysis of volatile compound changes in fried shallot (Allium cepa L. var. aggregatum) oil at different frying temperatures by GC-MS, OAV, and multivariate analysis

Flavor is a key attribute of fried oil that shows a critical correlation with temperature. Therefore, selecting the appropriate temperature is important in preparing fried shallot oil (FSO). Volatile compounds from five different FSOs were identified and comparatively studied using gas chromatography-mass spectrometry (GC-MS) coupled with multivariate data analysis, including principal component analysis (PCA) and orthogonal partial least squares discriminant analysis (OPLS-DA). GC-MS results identified a total of 93 volatiles, among which aldehydes, alcohols, pyrazines, and sulfur-containing compounds were the major compounds. Eighteen compounds had odor active values (OAV) >1. Among the compounds, hexanal, (E)-2-heptenal, (E)-2-octenal, dipropyl disulfide, 2-ethyl-3,5-dimethylpyrazine, and 1-octen-3-ol were important to the overall aroma profile of FSOs. In the PCA model, all the detected FSOs were divided into three clusters, which were assigned as cluster A (FSO5), B (FSO4), and C (the rest FSOs). Multivariate data analyses revealed that nonanal, 2-ethyl-5-methylpyrazine, (E,E)-2,4-decadienal, (E)-2-heptenal, and hexanal contributed positively to the classification of different FSOs. GC-MS coupled with multivariate data analysis could be used as a convenient and efficient analytical method to classify raw materials.

Addition of a mushroom by-product in oil-in-water emulsions for the microencapsulation of sunflower oil by spray drying

The by-product generated after ergosterol extraction from mushrooms (A. bisporus) is rich in polysaccharides (β-glucans) and proteins. The usefulness of this mushroom's by-product (MC) in oil microencapsulation by spray drying was evaluated partially replacing maltodextrin (13.5% w/w dry matter) and totally substituting Tween®20 with MC. Ergosterol was investigated as antioxidant. Non-Newtonian stable emulsions with mono-modal droplet size distributions were obtained with MC. Oil encapsulation efficiency was high (≥89%) and oil within microcapsules containing MC exhibited higher (p < 0.05) oxidative stability during spray drying. Powders containing MC exhibited larger particles (d₅₀27% larger), 12% lower solubility in water and perceptible color changes. During storage (35 °C 50% RH), conjugated dienes increased more slowly in microcapsules containing MC. Reductions up to 28% in linoleic acid were observed after 150 days. Ergosterol was 95% degraded after 150 days in powders with MC and totally degraded after 2 days in powders without MC.

Caryocar brasiliense Cambess. Pulp Oil Supplementation Reduces Total Cholesterol, LDL-c, and Non-HDL-c in Animals

The fruit of Caryocar brasiliense Cambess. is a source of oil with active compounds that are protective to the organism. In our work, we analyzed the physicochemical characteristics and evaluated the effects of supplementation with C. brasiliense oil in an animal model. We characterized the oil by indices of quality and identity, optical techniques of absorption spectroscopy in the UV–Vis region and fluorescence, and thermogravimetry/derived thermogravimetry (TG/DTG). For the animal experiment, we utilized mice (Mus musculus) supplemented with lipidic source in different dosages. The results demonstrated that C. brasiliense oil is an alternative source for human consumption and presents excellent oxidative stability. Primarily, it exhibited oleic MFA (53.56%) and palmitic SFA (37.78%). The oil level of tocopherols and tocotrienols was superior to the carotenoids. The supplementation with C. brasiliense oil reduced the levels of total cholesterol, LDL-c, and non-HDL-c. Regarding visceral fats and adiposity index, the treatment synergically supplemented with olive oil and C. brasiliense oil (OO + CO) obtained the best result. Therefore, C. brasiliense oil is a high quality product for consumption. Its supplementation promotes beneficial effects mainly on the lipidic profile.

Modeling the effect of heat treatment on fatty acid composition in home-made olive oil preparations

The aim of this study was to simulate olive oil use and to monitor changes in the profile of fatty acids in home-made preparations using olive oil, which involve repeated heat treatment cycles. The material used in the experiment consisted of extra virgin and refined olive oil samples. Fatty acid profiles of olive oil samples were monitored after each heating cycle (10 min). The outcomes showed that cycles of heat treatment cause significant (p < 0.05) differences in the fatty acid profile of olive oil. A similar trend of differences (p < 0.05) was found between fatty acid profiles in extra virgin and refined olive oils. As expected, the main differences occurred in monounsaturated fatty acids (MUFAs) and polyunsaturated fatty acids (PUFAs). Cross-correlation analysis also showed differences between the fatty acid profiles. The most prolific changes were observed between the control samples and the heated (at 180°C) samples of refined olive oil in PUFAs, though a heating temperature of 220°C resulted in similar decrease in MUFAs and PUFAs, in both extra virgin and refined olive oil samples. The study showed differences in fatty acid profiles that can occur during the culinary heating of olive oil. Furthermore, the study indicated that culinary heating of extra virgin olive oil produced results similar to those of the refined olive oil heating at a lower temperature below 180°C.

Comparison between synthetic and rosemary-based antioxidants for the deep frying of French fries in refined soybean oils evaluated by chemical and non-destructive rapid methods

Using natural antioxidants instead of synthetics ones has been the tendency for retarding the oil deterioration during repeated deep frying process. Concerning this, the comparison between synthetic tertiarybutyl hydroquinone (TBHQ) and rosemary-based antioxidants in frying French fries was hereby evaluated. The quality and stability of frying oils with rosemary-based antioxidants showed higher efficiency than TBHQ regarding oxidation parameters (i.e., chemical indices, sensory, etc.), where rosmarinic acid (RA) was the most effective, followed by rosemary extracts (RE) and carnosic acid (CA). LF-NMR results were highly correlated (R² = 0.909-0.998) to the change in physicochemical properties tested, where RA could effectively regulate the relaxation spectrum (T₂) change and decrease single component relaxation time (T_2W). The PCA graph of NIRS also revealed the dynamic change of antioxidant effectiveness in accordance with that obtained by chemical methods. Hence, both LF-NMR and NIRS can be expected as rapid and efficient methods for future monitoring the frying process.

Comparative Effects of Dietary Hemp and Poppy Seed Oil on Lipid Metabolism and the Antioxidant Status in Lean and Obese Zucker Rats

The objective of this study was to compare the effects of the dietary inclusion of hemp seed oil (HO) and poppy seed oil (PO) on the lipid metabolism and antioxidant status of lean and genetically obese Zucker rats. The rats were fed a control diet for laboratory rodents or a modification with HO or PO. Both oils reduced body and epididymal fat and liver cholesterol levels and promoted oxidative stress in the liver of obese rats. The HO reduced plasma triglycerides and had a stronger liver cholesterol-lowering effect in obese rats than PO. In the lean rats, HO and PO had no effects on the body fat content, plasma lipid profile, or lipid metabolism in the liver. HO considerably elevated the content of α-linolenic acid in the liver and increased the liver ratio of reduced glutathione (GSH)/oxidized glutathione (GSSG) in the lean rats. In conclusion, the regular consumption of both oils increases the accumulation of essential fatty acids in the liver of healthy animals, whilst not having any adverse effects on the body, whereas in genetically obese rats, the effects of both dietary oils on the lipid metabolism and antioxidant status are unequivocal and only partially beneficial.

The effect of fatty acid composition on the oil absorption behavior and surface morphology of fried potato sticks via LF-NMR, MRI, and SEM

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Oils’ fatty acid composition affects the oil absorption behavior of fried food.

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Oil content and distribution of samples are analyzed by LF-NMR and MRI.

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Oil content is positively correlated to peak height in the range of 20 ms–1000 ms.

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Viscosity of oils is positively correlated to total oil content of fried samples.

The oil absorption behavior of food during deep-frying greatly affects the quality of the final fried food. However, the research on oil absorption lacks comprehensive analysis and understanding. In this paper, the oil content, moisture content, oil distribution, and microstructure changes of fried potato sticks were explored via traditional method as well as advanced instruments, including low field nuclear magnetic resonance, magnetic resonance imaging, and scanning electron microscopy, and the differences and their corresponding relevance were analyzed and discussed. Results showed that the fatty acid composition of oils is highly related to their viscosity and surface tension, influencing the oil uptake of final products. Oil content was positively correlated with the peak height in the range of 20 ms–1000 ms (r² = 0.99348 at 140 ℃, r² = 0.99060 at 180 ℃). Oil distribution and microscopic morphology of the fried strips were affected by oil type and temperature.

Physiochemical properties of short-term frying oil for chicken wing and its oxidative stability in an oil-in-water emulsion

In this study, the physiochemical properties of corn oil and its oxidative stability in an O/W emulsion were studied following short-term (120 min) deep-frying of chicken wing. The results showed that the levels of polyunsaturated fatty acids in corn oil decreased after frying. Furthermore, total polar compound content in frying oil was significantly increased to 11.3%. Fourier transform infrared spectra (FTIR) indicated that hydrolysis and oxidation reactions involving triglycerides occurred after frying. Additionally, the increased a* and b* values demonstrated that deep-frying greatly enhanced the intensity of the red and yellow colors of corn oil. Frying reduced the oxidative stability of corn oil in an O/W emulsion as determined by the peroxide value and acid value. These findings indicated that short-term deep-frying of chicken wing deteriorated the quality of corn oil and decreased its oxidative stability in an O/W emulsion. Consumers should consider the potential hazards of food containing short-term deep-frying oil.