Thermostability and degradation kinetics of tocochromanols and carotenoids in palm oil, canola oil and their blends during deep-fat frying

Alterations in physico-chemical properties, microstructure, sensory characteristics, and volatile compounds of red pepper (Capsicum annuum var. conoides) during various thermal drying durations

Red pepper (Capsicum annuum var. conoides) is commonly used for dried pepper production in China, and the drying process, particularly the during duration, profoundly affects its quality. The findings indicate that prolonged exposure to high temperatures during thermal drying results in significant darkening, an evident decrease in red and yellow tones, and gradual transformation of the pepper's microscopic structure from granular to compact, along with 88% reduction in moisture content and 81% decrease in thickness. The capsaicinoid content increased, resulting in a 4.3-fold increase in spiciness after drying compared to that of fresh pepper. The pepper aroma shifts from fruity, choking, and grassy to herb, dry wood, and smoky. Compounds such as 2-Acetylfuran, furfural, 2-methylfuran, 1-methylpyrrole, 2-methylpyrazine, and 2,5-dimethylpyrazine exhibited positive correlations with drying time, whereas ethyl 2-methylpropanoate, ethyl butanoate, ethyl 2-methylbutanoate, ethyl hexanoate, and 3-methylbutyl butanoate showed negative correlations, indicating their potential as markers for monitoring thermal drying processes.

Investigation into the Reduction of Palm Oil in Foods by Blended Vegetable Oils through Response Surface Methodology and Oxidative Stability Tests

Recently, there has been a significant transition in the dietary preferences of consumers toward foods containing health-promoting compounds. In addition, as people's environmental awareness increases, they are increasingly looking for sustainable solutions. Palm oil, an oil used extensively by the food industry, does not fit these criteria. This study investigated the development of a complex oil blend consisting of commonly used vegetable oils such as corn, rapeseed, sunflower, and palm oil. The aim was to find the optimal blended oil and compare this combination with palm oil in terms of its oxidative stability, antioxidant capacity, and the composition of bioactive compounds (i.e., fatty acids, tocopherols, and carotenoids). Palm oil was found to have greater oxidative stability as a result of its increased concentration of saturated fatty acids. The optimal blended oil, which consisted of corn and rapeseed oil at a ratio of 4:3 w/w, inhibited the superior antioxidant activity, showing a ~33% increase in DPPH• inhibition activity. ATR-FTIR spectra further verified the existence of a significant quantity of saturated fatty acids in palm oil and unsaturated fatty acids in the blended oil. Finally, several correlation analyses revealed interesting connections between oil samples and investigated parameters. This work has the potential to establish a basis for the mass production of oil blends that possess high concentrations of antioxidant compounds and reduce the use of palm oil.

The interaction between lipid oxidation and the Maillard reaction model of lysine-glucose on aroma formation in fragrant sesame oil

The formation mechanism behind the sophisticated aromas of sesame oil (SO) has not been elucidated. The interaction effects of the Maillard reaction (MR) and lipid oxidation on the aroma formation of fragrant sesame oil were investigated in model reaction systems made of l-lysine (Lys) and d-glucose (Glc) with or without fresh SO (FSO) or oxidized SO (OSO). The addition of OSO to the Lys-Glc model increased the MR browning at 294 nm and 420 nm and enhanced the DPPH radical scavenging activity greater than the addition of FSO (p < 0.05). The presence of lysine and glucose inhibited the oxidation of sesame oil, reduced the loss of γ-tocopherol, and facilitated the formation of sesamol (p < 0.05). The Maillard-lipid interaction led to the increased concentrations of some of the alkylpyrazines, alkylfurans, and MR-derived ketones and acids (p < 0.05) while reducing the concentrations of other pyrazines, lipid-derived furans, aliphatic aldehydes, ketones, alcohols, and acids (p < 0.05). The addition of FSO to the MR model enhanced the characteristic roasted, nutty, sweet, and fatty aromas in sesame oil (p < 0.05), while excessive lipid oxidation (OSO) brought about an unpleasant oxidized odor and reduced the characteristic aromas. This study helps to understand the sophisticated aroma formation mechanism in sesame oil and provides scientific instruction for precise flavor control in the production of sesame oil.

Elevated temperature extraction of β-carotene from freeze-dried carrot powder into sunflower oil: Extraction kinetics and thermal stability

β-Carotene, a precursor of vitamin A, can alleviate the deficiency of this vitamin prevalent worldwide. Earlier research studies have addressed the extraction of β-carotene at relatively low temperatures (up to 70°C) due to its perceived instability at higher temperatures, as a result of which extraction rates recorded are relatively low. This study models the net rate of β-carotene extraction by considering both extraction and degradation kinetics. The model developed, which accounts for degradation occurring in solid and extract phases, has been experimentally validated for the extraction of β-carotene from freeze-dried carrot powder into sunflower oil over a range of temperatures 90-150°C. This study also gives insights into the application of sunflower oil as a carrier for β-carotene during cooking and food processing, by monitoring and modeling the thermal degradation and isomerization of β-carotene at temperatures up to 220°C. The modeling of extraction kinetics shows that it is possible to achieve viable extraction rates by employing temperatures in the range (90-150°C) for relatively short times (<5 min). The degradation kinetics shows that almost 75% of the β-carotene can survive heating at 180°C for 10 min-indicating the possibility of using β-carotene enriched edible oils for frying. This study also reports on the formation of three isomers of β-carotene identified using HPLC: trans-, 9-cis, and 13-cis. The reaction network model developed in this study was able to account for the transient variation of the concentration of all three isomers. PRACTICAL APPLICATION: β-Carotene is a precursor of vitamin A and its consumption can potentially alleviate the deficiency of this vitamin prevalent worldwide. This study validates a model for the extraction of β-carotene in sunflower oil, which takes into account extraction as well as degradation occurring during extraction, so that a rational method is available for the design of efficient extractors for this purpose. This paper also establishes the thermal stability of β-carotene under frying conditions by quantifying its thermal degradation as well as isomerization.

Chemical-Physical Properties of Red Palm Oils and Their Application in the Manufacture of Aerated Emulsions with Improved Whipping Capabilities

Red palm oil (RPO), which is rich in micronutrients, especially carotenoids, is different from its deodorized counterpart, palm oil. It is considered as one of the most promising food ingredients, owing to its unique compositions and nutritional values, while its usage could be further developed by improving its thermal behaviors. In this article, two typical commercial RPOs, HRPO (H. red palm oil) and NRPO (N. red palm oil), were evaluated by analyzing their fatty acids, triacylglycerols, micronutrients, oxidative stability index (OSI), and solid fat contents (SFCs). Micronutrients, mainly carotenes, tocopherols, polyphenols, and squalene, significantly increased the oxidative stability indices (OSIs) of the RPOs (from 10.02 to 12.06 h), while the OSIs of their micronutrient-free counterparts were only 1.12 to 1.82 h. HRPO exhibited a lower SFC than those of NRPO. RPOs softened at around 10 °C and completely melted near 20 °C. Although the softening problem may limit the usages of RPOs, that problem could be solved by incorporating RPOs with mango kernel fat (MKF). The binary blends containing 40% RPOs and 60% MKF exhibited desirable compatibilities, making that blend suitable for the manufacture of aerated emulsions with improved whipping performance and foam stabilities. The results provide a new application of RPOs and MKF in the manufacture of aerated emulsions with improved nutritional values and desired whipping capabilities.

Multi-dimensional pungency and sensory profiles of powder and oil of seven chili peppers based on descriptive analysis and Scoville heat units

The pungency and flavor experience of peppers determines their economic benefits and consumption; thus, a systematic sensory evaluation of peppers is essential to monitor their production. Here the Scoville heat units (SHUs) of powders and oils of seven commercial peppers in China (i.e., Indian, Erjintiao, Shizhuhong, Zidantou, Xinyidai, Mantianxing and Denglong) were derived based on concentrations of capsaicin and dihydrocapsaicin. Then, the pungency and sensory profiles of pepper products were investigated by 11 trained panelists. The potential indicators for predicting perceived pungency in peppers were found based on correlation analysis. The Indian pepper stood out for its highest SHU (85909), bright redness, peppery, and bitterness, but lacked herb/woody flavor. But other species had more varied flavor profiles and gentler mouth-feelings. SHU and capsaicin were more recommended in predicting the perceived pungency in pepper powder and pepper oil. This study offers a framework for evaluating the sensory characteristics of pepper products.

Balancing functional and health benefits of food products formulated with palm oil as oil sources

Palm oil (PO) is widely utilised in the food industry and consumed in large quantities by humans. Owing to its bioactive components, such as fatty acids, carotenoids, vitamin E, and phenolic compounds, PO has been utilised for generations. However, public concern about their adverse effects on human health is growing. A literature search was conducted to identify fractionated palm oil processing techniques, proof of their health advantages, and potential food applications. Refined palm oil (RPO) is made from crude palm oil (CPO) and can be fractionated into palm olein (POl) and palm stearin (PS). Fractional crystallisation, dry fractionation, and solvent fractionation are the three basic fractionation procedures used in the PO industry. The composition of triacylglycerols and fatty acids in refined and fractionated palm oil and other vegetable oils is compared to elucidate the triacylglycerols and fatty acids that may be important in product development. It is well proven that RPO, POl, and PS extends the oil's shelf life in the food business. These oils have a more significant saturated fat content and antioxidant compounds than some vegetable oils, such as olive and coconut oils, making them more stable. Palm olein and stearin are also superior shortening agents and frying mediums for baking goods and meals. Furthermore, when ingested modestly daily, palm oils, especially RPO and POl, provide health benefits such as cardioprotective, antidiabetic, anti-inflammatory, and antithrombotic effects. Opportunities exist for fractionated palm oil to become a fat substitute; however, nutrition aspects need to be considered in further developing the market.

Chemical characterization of baru oil and its by-product from the northwest region of Minas Gerais, Brazil

This study investigated baru oil and partially defatted baru flour from the northwest region of Minas Gerais, Brazil. The physicochemical characterization of the oil was made by determining the fatty acid profile using gas chromatography, lutein, and α- and β- carotenes by means of high-performance liquid chromatography, and total carotenoids by spectrophotometry. The flour was analyzed for its chemical composition, fiber, and mineral contents. Baru oil presented excellent quality parameters and high contents in unsaturated fatty acids and carotenoids. The flour showed relevant levels of proteins, lipids, and dietary fiber, in addition to having representative mineral contents for food such as manganese, magnesium, and copper. Thus, baru oil and the by-product of its extraction offer a rich chemical composition, and their application may add nutritional value to foods in addition to reducing negative environmental impacts.

Pilot scale production of functional foods using red palm olein: Antioxidant, vitamins' stability and sensory quality during storage

The objective of this research work was to produce acceptable quality functional foods, namely, extruded snacks, digestive biscuits and pan bread, on a pilot scale, using vitamin E and β-carotene-rich red palm olein (RPOL) and red palm shortening (RPS). These products were evaluated for their chemical composition and sensory quality along with the antioxidants and vitamin contents during the six months of storage at room temperature (22 ± 1 °C). Extruded snacks and digestive biscuits prepared with RPOL and RPS were found to be good sources of these antioxidant vitamins. The average β-carotene content of the control and test snacks at the end of six months of storage ranged from 26.8 to 56.1 mg/kg fat, and from 430.9 to 468.9 mg/kg fat, respectively. The total vitamin E content in control and test snacks made in Plant No. 1 decreased after six months of storage from 786.1 to 704.4 mg/kg fat, and from 765.1 to 695.4 mg/kg fat, respectively. As expected, the total tocotrienol content was four to five times higher than the total tocopherols in control biscuits. The RPOL containing 600–750 ppm of carotenes (mainly α- and β-carotenes), 710–774 ppm of vitamin E, was found to be suitable for industrial application in producing acceptable quality pan bread, digestive biscuits and snacks. These functional foods contained significant amounts of β-carotene and total vitamin E, indicating the possibility of producing such foods rich in these two of the important antioxidant vitamins coming from a natural source. The research findings strongly indicate that good-quality pan bread, extruded snacks and digestive biscuits can successfully be produced to offer healthier eating choices to the consumers of this region, thereby promoting better health and productivity among the population.

Zeaxanthin in Soybean Oil: Impact of Oxidative Stability, Degradation Pattern, and Product Analysis

In this study, the antioxidant capacity and oxidative stability of zeaxanthin with different concentrations in soybean oil were evaluated. The oxidative or isomerization products of zeaxanthin were monitored during oxidation for 12 h at 110 °C. It was found that the ability to scavenge the free radicals (DPPH, FRAP, and ABTS) was dependent upon the concentration of zeaxanthin. However, antioxidation of zeaxanthin was observed when the concentration was less than 50 μg/g. When the concentration exceeded 50 μg/g, zeaxanthin acted as a pro-oxidant. There were three kinds of non-volatile products of zeaxanthin that were detected: (a) Z-violaxanthin, (b) 9-Z-zeaxanthin, and (c) 13-Z-zeaxanthin, and it was found that the content of 13-Z-zeaxanthin formed by isomerization was the highest. In addition, the linear ketone (6-methyl-3,5-heptadien-2-one) and cyclic volatile products (3-hydroxy-β-cyclocitral, 3-hydroxy-5,6-epoxy-7,8-dihydro-β-ionone, and 3-hydroxy-β-ionone) formed by in situ oxidative cleavage were identified.

Different Processing Practices and the Frying Life of Refined Canola Oil

Refined expeller-pressed (RCanO-I and RCanO-II) and expeller-pressed and solvent-extracted blended (RCanO-III and RCanO-IV) canola oils were compared to determine the effect of processing (extraction) practice on the frying life of canola oil. Samples were from the 2016/2017 and 2017/2018 production seasons and were used to fry potato chips for 36 to 48 cycles. Frying life was assessed by the total polar compounds, retention of tocopherols, antioxidant activity, and other quality indices. RCanO-II exhibited significantly, the longest frying life as compared with the other three oils and this correlated with tocopherol retention and antioxidant activity (p < 0.05). The extraction practice influenced the frying life of canola oil, but this was dependent on other processing practices employed by the individual processors. Variations in initial oil quality dictated the rates of chemical reactions occurring in the oils during frying and influenced oil stability.

Comparison of the Oxidative Stability and Antioxidant Activity of Extra-Virgin Olive Oil and Oils Extracted from Seeds of Colliguaya integerrima and Cynara cardunculus Under Normal Conditions and After Thermal Treatment

We investigated the potential of two oil extracts from seeds of Colliguaya integerrima (CIO) and Cynara cardunculus (CO) to use as nutritionally edible oils. For this purpose, oil quality was accessed by determining the fatty acid composition, peroxide value, acid value, iodine value, saponification number, phenolic contents, and oxidative stability during thermally induced oxidation of CIO and CO oils and compared to those of extra-virgin olive oil (EVOO). The chemical composition results demonstrated that both oils could be nutritional sources of essential unsaturated fatty acids. Moreover, according to the gravimetric analysis, the main decomposition step occurred in the temperature range of 200-420 °C, showing a similar thermal behavior of EVOO oil. However, CO and EVOO oils showed a higher phenolic content at degradation onset temperature (T0) in contrast with CIO oil. The antioxidant activity of the different studied oils showed a direct correlation with the phenol contents, up to temperatures around 180 °C, where the percentage of free radical scavenging assay for EVOO was higher than CO in contrast with the TPC values. Finally, we analyzed the minor components before and after heating CIO and CO at 180 °C by gas chromatography-mass spectrometry (GC-MS) using library search programs.

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

Oil deterioration during deep-frying influences the quality of fried foods to a great extent. In this study, the frying performance of six vegetable oils, i.e., hemp, lupin, oat, rapeseed, soy, and sunflower, was evaluated following short-term (60 min) deep-frying of French fries at 180 °C. The frying oils were investigated for fatty acid profile, volatile compound composition, and parameters of oxidative stability, such as iodine, peroxide, and p-anisidine values. The examination showed that the content of ƩPUFA in hemp oil decreased significantly (p < 0.05) after 60 min of deep-frying, although the degree of change was relatively small (close to 1.5%). Similarly, soy oil presented a fatty acid profile prone to oxidation, and generated the highest level of peroxides at the end of the thermal treatment (PV = 16.6 ± 2.3 mEq O₂ kg^-1). As for the volatile compound composition of the oils, sunflower oil was extensively affected by the deep-frying treatment with a significant decrease (p > 0.05) in total terpenes, accompanied by a considerable rise in total aldehydes. Oppositely, the proportions of MUFA and PUFA of lupin and oat oils remained stable (p > 0.05) during the short-term deep-frying, indicating high stability of these oils. The research provided new data for evaluating the suitability of these oils for household food preparations.

Changes in quality and phytochemical contents of avocado oil under different temperatures

Avocado oil, which has a high content of monounsaturated fatty acid and health-beneficial phytochemicals, is consumed in salads and also can be used for cooking. Therefore, is essential to study its oxidative and photochemical stability under different temperatures. So this work aimed to evaluate the oil oxidation and the phytochemical degradation of avocado oil under three different temperatures: room, 100 °C and 180 °C. The oil oxidation was evaluated by peroxide value and specific extinction in ultraviolet. The phytochemical degradation was evaluated for phytosterol, chlorophylls, and carotenoids contents. The temperature was found to significantly influence the oil oxidation and phytochemical stability, with the oxidation/degradation rate constants increasing with temperature. At room temperature, all oxidative parameters increased linearly with time, indicating a zero-order kinetic. At 100 and 180 °C, peroxide value, K232 and K270 increased linearly at a higher rate, becoming constant or decreasing after a short reaction time. The activation energy from specific extinction at 270 nm curves was 17.74 kcal mol^-1 for oil degradation. For phytochemical compounds, the mechanism of reactions depended on the temperature, in which the reaction orders increased with heating. The activation energies for carotenoids, chlorophylls and sterols degradations at high temperatures were 5.00, 6.93, and 4.48 kcal mol^-1, respectively. In this way, we found that avocado oil has its stability and quality affected by temperature, and, therefore, is not indicated for use in long and/or successive heating processes.