Rancimat Test Research Articles

Chemical Composition, Antioxidant and Antibacterial Activities of Essential Oil Obtained from Chincho (Tagetes elliptica Sm) Leaves Grown in the Peruvian Andes

The chemical composition, antioxidant, and antibacterial properties of the essential oil from the leaves of Tagetes elliptica Sm., grown in Peru, were studied. The EO was extracted using steam distillation, and its chemical composition was analyzed using GC-MS, while the antioxidant activity was evaluated using the radical, scavenging capacity (DPPH and ABTS assays), and ferric reducing antioxidant power (FRAP) assays, ferrous ion chelating (FIC) activity, and the Rancimat test. The antibacterial activity against Staphylococcus aureus, Escherichia coli, and Salmonella infantis was studied using the agar well diffusion method. Twenty-seven compounds were identified in the essential oil, and the major components were cis-tagetenone (37.27%), trans-tagetenone (18.84%), dihydrotagetone (14.38%), and trans-tagetone (5.15%). With regard to antioxidant properties, the IC50 values obtained for the DPPH, ABTS, and FIC assays were 53.37, 46.38, and 22.65 mg/mL, respectively. These values were lower than those obtained for standard butylated hydroxytoluene and ascorbic acid. In the Rancimat test, antioxidant activity was achieved only at high concentration. T. elliptica essential oil showed a marked antibacterial activity against all bacterial strains at all concentrations assayed. This study demonstrated that T. elliptica essential oil could be considered as an alternative to synthetic antioxidants and antimicrobial agents in the food industry.

Physicochemical Properties and Sensory Attributes of Cold-Pressed Camelina Oils from the Polish Retail Market

Cold-pressed camelina oil (CPCO) is exceptional seed oil with a unique fatty acid profile promoting health and wellness. Therefore, this work focused on estimating and comparing the physicochemical properties and sensory quality of eight CPCO samples available on the Polish market. All analyzed oils were rich in α-linolenic acid (ALA = 29.91–36.27%) and contained low amounts of saturated fatty acids (SAFA = 10.61–12.20%). Oxidative stability of the studied CPCO samples, using the Rancimat test, ranged between 4.8 and 6.8 h, while peroxide (PV = 0.58–4.61 meq O2/kg) and anisidine (AnV = 0.15–1.60) values differed significantly. Moreover, the water and volatile matter contents (WVMC = 0.05–0.17%) and phosphorus level (P = 3.03–13.58 mg/kg) were monitored in commercial CPCO samples. Low concentrations of polycyclic aromatic hydrocarbon contaminants (Σ4PAHs = 0.72–7.22 μg/kg) were established in all oils. A quantitative descriptive analysis (QDA) was developed to characterize the sensory properties of eight CPCO samples. Six oil samples had high overall sensory quality (OSQ > 4.0), but OSQ < 3.5 was an unacceptance sensory quality for two of the oils. The developed lexicon might be used in the oil industry to monitor product quality, sensory profiling of new product development, and benchmark competitors’ samples.

Zeaxanthin Combined with Tocopherol to Improve the Oxidative Stability of Chicken Oil.

Chicken oil is prone to oxidation due to the high content of unsaturated fatty acids. The interaction of antioxidants was affected by their concentration, ratio, and reaction system. In this article, mixtures of zeaxanthin and tocopherols (α-tocopherol and γ-tocopherol) were chosen to enhance the oxidative stability of chicken oil. The antioxidation of zeaxanthin with tocopherols was analyzed using the Rancimat test, the free radical scavenging capacity and the Schaal oven test (the variation of antioxidant content, PV and shelf life prediction). The optimal concentration of zeaxanthin determined by Rancimat in chicken oil was 20 mg/kg. The binary mixtures have a strong synergistic effect in the ABTS experiment, and the clearance rate was up to 99%, but antagonistic effect in ORAC. The degree of synergism between zeaxanthin and tocopherols was determined by ratio. The interaction between zeaxanthin and α-tocopherol was synergistic, while the types of interaction between zeaxanthin and γ-tocopherol were affected by concentration. The main synergistic interaction mechanism was the regeneration of tocopherol by zeaxanthin. Synergistic combinations of zeaxanthin with α-tocopherol and γ-tocopherol played a key role in the primary oxidation stage of the lipid. The best synergistic combination was A3 (zeaxanthin+α-tocopherol: 15+50 23 mg/kg), which could extend the shelf life of chicken oil (92.46 d) to 146.93 days. This work provides a reference for zeaxanthin and tocopherol to improve the oxidative stability of animal fat.

Valorization of apricot, melon, and watermelon by-products by extracting vegetable oils from their seeds and formulating margarine

Vegetable oils extracted from seeds and oleaginous fruits are a substantial source of bioactive compounds. In this study, oils of some fruit by-products were investigated and their composition and properties were compared. Apricot (ASO), melon (MSO), and watermelon (WSO) seed oils were extracted by cold pressing. The physico-chemical parameters and the contents of pigments were assessed using standard methods. The values of the physico-chemical parameters revealed the purity of the oils and it was recorded that the WSO has the best contents of chlorophylls and carotenoids, which were 12.43 ± 0.71 mg/kg of oil, and 1.35 ± 0.02 mg equivalent of β-carotene/g oil, respectively. In addition, the oils were analyzed by gas chromatography and their major fatty acids were linoleic, oleic, palmitic, and stearic. The ASO revealed the highest antioxidant activity in the quenching of 1,1-diphenyl-2-picrylhydrazyl (DPPH) with inhibition percentage of 89.2 ± 2.3 after 30 minutes of contact. Likewise, the oils were explored for the fortification of margarine. The physicochemical parameters of the formulated margarines comply with the standards. The Rancimat test showed that the highest induction time (16.54 h) was assigned to margarine enriched with 150 μg/g of WSO. Hence, this oil can has numerous applications in other food industries.

Thermo-physical Properties and Oxidative Stability of the Oil of Babassu Palm (Attalea vitrivir Zona, Arecaceae)

Population growth and the concern about its environmental impact have increased the demand for vegetable oils in recent years. Vegetable oils are used in several industry sectors and have been investigated as an alternative energy source to replace traditional fossil fuels. Knowledge of physical and chemical properties is essential to assess the potential use of vegetable oil in the production of biofuels. The present study aimed to determine the oxidative stability of the seed oil of the babassu palm tree, Attalea vitrivir, native to the Brazilian cerrado and originated from two different regions, before and after storage for 12 months. The relative density of the oil did not differ between regions and did not change over time. Kinematic viscosity was lower for area 1 and increased with storage in oils from both areas. The induction period in the Rancimat test was lower in area 2 and decreased in the stored oil, regardless of the area, though it remained higher than the minimum required for its use as biofuel. The evaluation of oxidation by the oven method also showed satisfactory results, confirming the high thermo-oxidative stability of the babassu oil rich in lauric acid.

Oxidation kinetic studies of virgin and solvent extracted pistachio oil under Rancimat test conditions

Oxidation kinetic studies of virgin and solvent extracted pistachio oil under Rancimat test conditions

Emission analysis and optimization of antioxidant influence on biofuel stability.

Taking the unbalanced properties of biodiesel leading to rapid oxidation as the maxim of this research, with the aid of weightage evaluation and optimization techniques like Criteria Importance Through Intercriteria Correlation and Evaluation based on Distance from Average Solution (EDAS), Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) respectively, the ranking of each sample with elevated stability parameters has been projected through rancimat test for oxidation, kinematic viscosity and acid value test for storage, and thermo gravimetric analyzer test for thermal stability parameters. To make sure that the obtained parameter consequences are truthful, Fourier Transform Infrared Spectroscopy has been used as the correlating tool in this research. Twenty percent of the biodiesel with Tert butyl hydroquinone (T) at 1000ppm (3) is mixed to diesel and emission characteristics like carbon monoxide, carbon dioxide, hydrocarbon, smoke opacity, and nitrous of oxide have been analyzed for diesel, B20 = 20% biodiesel + 80% diesel, and B20T3. Among every five sets of concentration and antioxidant (T and Pyrogallol-PY) dosed samples, an average of 9.93% elevated oxidation stability, 1.19%, and 4.51% lower kinematic viscosity and acid value, and 25.35% higher thermal stability have been obtained for B100T3 = Pure biodiesel + T3. An elevated appraisal score and performance score of 1.000 and 0.998 by EDAS and TOPSIS respectively for B100T3 blend has also been obtained. Except for carbon dioxide and nitrous of oxide, other emission levels in B20 and B20T3 samples decrease when compared to diesel. While comparing B20 and B20T3 poisonous nitrous of oxide emission levels, the B20T3 sample shows an average decrease of 9.37% when compared to B20 sample due to the suppressing action of antioxidants.

Ethanolic extract of rice bran: a thermally stable preservative for edible oils and cake

The purpose of this study was to evaluate the thermal stability of the rice bran extract (RBE) and analyze the effect of RBE on the shelf-life of sunflower oil and the quality characteristics and shelf-life of baked cake. The thermal stability of RBE was evaluated by a Rancimat test using sunflower oil. Properties such as moisture content, porosity, crumb density and pore area of cakes baked with RBE and the synthetic antioxidant butylated hydroxytoluene (BHT) were compared. Sensory properties such as taste, aroma, texture, color and overall acceptability of the cake samples were compared using a sensory panel test. The shelf-life of the cakes was evaluated by microbial counts and chemical methods. Thermally treated RBE and BHT for 2 h at 180 °C retained 75% of their initial capacity in protecting sunflower oil while RBE had a significantly higher protection factor (p < 0.05). Cakes baked with RBE received higher scores for taste, color and overall acceptability compared to control or BHT-added cake. BHT-added cake and RBE-added cake exceeded the aerobic plate count (APC) and yeast and mold count (YMC) on days 11 and 13 respectively, while the control cakes without added antioxidants exceeded the APC and YMC on day 7. Both BHT- and RBE-added cakes maintained hexanal levels below 5 mg/kg over 28 days while the control cake exceeded this level on day 21. The results suggest that RBE can be used as a natural food additive to improve the quality and shelf-life of baked foods and edible oils.Graphical

Pflanzliche Antioxidantien für Bioschmierstoffanwendungen

Plant extracts from natural and renewable resources have the potential to replace conventional antioxidants in many applications and to increase the stability of lubricants. By specific selection of raw materials and adaptation of extraction parameters, the properties of the additives can be specifically optimized for the respective application. Easy-to-perform photometric assays enable targeted and rapid process adjustment and pre-selection of extracts. Later, they can be evaluated in application-oriented analytical methods, such as the rancimat test, with regard to their effect in the oil. In our analyses, secondary plant compounds increased the oxidation stability by 300 %, whereas the conventional antioxidants only achieved an increase of 200 %.

Polyphenols from Plants: Phytochemical Characterization, Antioxidant Capacity, and Antimicrobial Activity of Some Plants from Different Sites of Greece

Polyphenols are present in many plants and herbs, and the scientific community and consumers are aware of their health-promoting effects. Plants of Greek origin were studied for their polyphenol content and their antioxidant and antimicrobial activities. Gas chromatography–mass spectrometry (GC–MS) and high-performance liquid chromatography coupled to a diode array detector (HPLC–DAD) were used for the identification and characterization of plant polyphenols. For GC–MS, a silylation procedure was employed. Ferulic acid, quercetin, and catechin were the most abundant polyphenols. The Rancimat test, FRAP (Ferric-reducing Antioxidant power) assay, and DPPH (2,2-Diphenyl-1-picrylhydrazyl) assay were used to study the antioxidant capacity, which was proven for all studied plants. The antimicrobial activity was studied against specific pathogenic microorganisms. Pelargonium purpureum and Sideritis scardica plant extracts inhibited most microorganisms such as L. monocytogenes and E. coli. Extracts of studied plants showed both antioxidant and antimicrobial activities; hence, they can be considered to be used by the food industry.

A comparative study of lipid oxidation in garlic oil ( Allium sativum L.): An accelerated oxidation

This study has produced comparative findings on the quality (flavonoid and phenolic concentrations, antioxidant activity, and free fatty acids) and shelf-life of garlic (Allium sativum L.) oil. Commercial (two different brands) and homemade products were used. The shelf life of the products was determined by Rancimat tests performed at 110, 120, 130, and 140°C. Principal component analysis has been employed to establish a relationship between the quality measurements. To appraise the structure of the lipid oxidation in the oil samples, thermodynamic and kinetic parameters have also been derived depending on the induction times obtained at different temperature values. One of the commercial oils has showed the longest shelf life (131 days), while the shelf life of the homemade one has been calculated as 111 days. The commercial-2 garlic oil displayed the highest Gibbs free energy. Novelty impact statement The quality of garlic oils was measured regarding TPC, TFA, antioxidant capacity, free fatty acid value, and shelf life. A statistical technique employing PCA was used to compare two commercial and one handmade garlic oils. This research served to determine the storage stability of homemade garlic-infused olive oil and garlic-infused canola oil that can be used as herbal supplements.

Quantitative Structure-Property Relationship (QSPR) of Plant Phenolic Compounds in Rapeseed Oil and Comparison of Antioxidant Measurement Methods

Natural antioxidants are known for their ability to scavenge free radicals and protect oils from oxidation. Our aim was to study the structural properties such as the number of hydroxyl groups and Bors criteria of phenolic substances leading to high antioxidant activity in oil in order to analyze common trends and differences in widespread in vitro antioxidant assays. Therefore, 20 different phenolic substances were incorporated into rapeseed oil and were measured using pressurized differential scanning calorimetry (P-DSC) and the Rancimat method. The Bors criteria had the highest influence on the antioxidant effect in rapeseed oil, which is why myricetin (MYR), fulfilling all Bors criteria, reached the highest result of the flavonoids. In the Rancimat test and P-DSC, MYR obtained an increase in oxidation induction time (OIT) of 231.1 ± 44.6% and 96.8 ± 1.8%, respectively. Due to differences in the measurement parameters, the results of the Rancimat test and P-DSC were only partially in agreement. Furthermore, we compared the results to in vitro assays (ABTS, DPPH, FC and ORAC) in order to evaluate their applicability as alternative rapid methods. These analysis showed the highest correlation of the oil methods with the results of the DPPH assay, which is, therefore, most suitable to predict the antioxidant behavior of oil.

Study of the thermal behavior of rosemary extract and its temperature‐related antioxidant effect on chicken fat

The relationship between the thermal behavior and antioxidant stability of rosemary extract (RE) was investigated. Through simultaneous thermal analysis (TG-DTA) and total phenolic content measurement, stability of RE below 200°C and the resistance of phenolics below 130°C have been found, revealing an asynchrony between weight loss and destruction of antioxidant capacity. Peroxide value, p-anisidine value, TG-DTA, Rancimat test, and kinetic analysis of chicken fat at 90–150°C were also carried out to further determine the antioxidant stability of RE on the oxidation and degradation of edible fats. Consequently, the highest antioxidant activity index is 6.49 at 120°C, and RE elevates the initial degradation point of chicken fat under thermal stress by reducing oxygen absorption. Besides, the antioxidant effect of RE is found to be weaker due to the thermal destruction of the phenolics, but a higher temperature below the destruction point can cause a better antioxidant effect. Novelty impact statement The antioxidant effect of RE is related to temperature and the thermal stability of components. The thermal behavior and antioxidant stability of rosemary extract are inconsistent. Rosemary extract shows the best antioxidant effect below the destruction point (130 °C) despite the severer oxidation of chicken fat with increasing temperature.

Characterization of Buriti (Mauritia flexuosa) Pulp Oil and the Effect of Its Supplementation in an In Vivo Experimental Model.

Mauritia flexuosa (Buriti) pulp oil contains bioactive substances and lipids that are protective against cardiovascular and inflammatory diseases. We performed physical and chemical analyses to verify its quality and stability. Buriti oil was stable according to the Rancimat test, presenting an induction period of 6.6 h. We evaluated the effect of supplementation with crude buriti oil and olive oil on metabolic parameters in 108 Swiss mice for 90 days. We investigated six groups: extra virgin olive oil (EVOO) 1 and 2 (1000 and 2000 mg/kg), buriti oil (BO) 1 and 2 (1000 and 2000 mg/kg), synergic (S) (BO1 + EVOO1), and control (water dose 1000 mg/kg). The animals were euthanized to examine their blood, livers, and fats. The supplementation did not interfere with food consumption, weight gain, and histological alterations in the liver. Group S showed the strongest relationship with the fractions HDL-c and non-HDL-c, indicating a possible cardioprotective effect. Moreover, we observed significantly higher IL-6 levels in the control, EVOO2, and BO1 groups than in the EVOO1 group. Resistin was also significantly higher for the synergic treatment than for the control. We conclude that BO combined with EVOO could be an excellent food supplement for human consumption.

Efficacy of canolol and guaiacol in the protection of cold-pressed oils being a dietary source linoleic acid against oxidative deterioration

Oils high in linoleic acid are the main sources of polyunsaturated fatty acids in the human diet. The study attempted to increase the oxidative stability of 11 cold-pressed oils with various linoleic acid percentages by adding phenolic acid derivatives (canolol, guaiacol) at concentrations of 20–100 ppm. The oils were characterized by acid, peroxide and anisidine values, diene, triene, and water contents, fatty acid composition, and bioactive compounds. Their oxidative stability was evaluated before and after the addition of phenolic acid derivatives in the Rancimat test. The results indicate that both additives can be deployed as antioxidants in linoleic acid-rich oils, but canolol elicits a stronger protective effect (over fourfold). 100 ppm of canolol caused a significant increase in the oxidative stability of most oils (31–79%). The guaiacol effectiveness was greater (13–19% increase) at higher concentrations in hemp and poppy oils, but its lower amounts were more relevant for other oils.

Two Novel Lipophilic Antioxidants Derivatized from Curcumin.

Tert-butyl curcumin (TBC), demethylated tert-butylated curcumin (1E,6E-1,7-bis(3-tert-butyl-4,5-dihydroxyphenyl)hepta-1,6-diene-3,5-dione, DMTC), demethylated curcumin (DMC), and Cur were synthesized from the starting compound, 2-methoxy-4-methylphenol. TBC and DMTC are two novel lipophilic compounds, and Cur and DMC are polar and hydrophilic. The antioxidant activities of Cur, TBC, DMC, and DMTC were evaluated by using the methods of 2,2-diphenyl-1-(2,4,6-trinitro-phenyl)-hydrazinyl (DPPH), deep-frying, and Rancimat. Tert-butylhydroquinone (TBHQ) and Butylated hydroxytoluene (BHT) were used as comparison compounds. Both Rancimat and deep-frying tests demonstrated that DMTC was the strongest antioxidant, and TBC also had stronger antioxidant activity than Cur. In the DPPH assay, DMC showed the highest scavenging activity, followed by DMTC, TBHQ, Cur, and TBC. DMTC and TBC can be potentially used as strong antioxidants in food industry, especially for frying, baking, and other high temperature food processing. DMTC is the strongest antioxidant in oil to our knowledge.

Rosemary Extracts Improved the Antioxidant Status of Low-Fat Yoghurt Sauces Enriched with Inulin

Yoghurt sauces are considered fatty products which are quite susceptible to oxidation and must be stabilised using antioxidants. Novel formulations for yoghurt sauces often involve replacement of fat with dietary fibres and use of natural preservatives. The aim of the present research was to design healthier formulations for yoghurt sauces based on the replacement of sunflower oil (SO) with chicory inulin (IN) and the use of rosemary extracts (RE) as natural antioxidants. Different sauces were developed by adding IN at 2 and 5% w: w and/or 300 mg/kg lipo- and/or water-soluble rosemary extracts (RLE and/or RWE) containing 120 and 146 mg polyphenols per g extract, respectively. Nutritional value (proximate composition and caloric contribution), some physical properties (pH and CIELab colour) and antioxidant status (deoxyribose, DPPH radical scavenging, Rancimat, lipid peroxidation and linoleic acid assays) were assessed in the sauces. Replacement of SO with IN (5%) reduced fat content by 30%, roughly 15% low calories, thereby obtaining healthier sauces. As expected, the RLE was more effective than the RWE in improving antioxidant activity in lipidic environment. Using RLE enhanced the antioxidant capacity of lipid peroxidation by 44%. In the Rancimat test, this increased the oxidative protection of the sauce made with and without IN (5%) by around 20% or 45%, respectively. Similarly, using RLE doubled protection against linoleic acid oxidation. Application of IN in yoghurt sauce has nutritional (replacement of lipids with dietary fibre) and technological interest (foaming agent) and can be combined with RE of high polyphenol content as a potential functional ingredient capable of stabilising the sauces against oxidation.

Application of Chromatographic and Thermal Methods to Study Fatty Acids Composition and Positional Distribution, Oxidation Kinetic Parameters and Melting Profile as Important Factors Characterizing Amaranth and Quinoa Oils

Amaranth and quinoa are classed as pseudocereals that do not belong to the grass family, meaning they are not technically a grain. Both of them are seeds with tremendous nutritional value; compared to other cereals, they contain much more fat. The aim of the study was to present the parameters characterizing thermal properties of amaranth and quinoa oils, such as: oxidation induction time, oxidation kinetic parameters, and melting profile. In isolated oils, the peroxide value, oxidative stability by the Rancimat test (in 120 °C) and the pressure differential scanning calorimetry (PDSC) method (at 100, 110, 120, 130, 140 °C), fatty acids composition, and their distribution between the triacylglycerol positions were determined. The kinetic parameters of the oxidation process (activation energy, pre-exponential factor, and reaction rate constants) were calculated using the Ozawa–Flynn–Wall method and the Arrhenius equation. To measure the melting profile, the differential scanning calorimetry (DSC) method was used. Both types of seeds are a good source of unsaturated fatty acids. Induction time of oxidation suggests that amaranth oil may have better resistance to oxidation than quinoa oil. The melting characteristics of the oils show the presence of low-melting triacylglycerol fractions, mainly containing unsaturated fatty acids, which means that a small amount of energy is required to melt the fats.

Effect of initial quality and bioactive compounds content in cold-pressed flaxseed oils on oxidative stability and oxidation products formation during one-month storage with light exposure

Flaxseed oils contain significant amounts of unsaturated fatty acids and, consequently, are susceptible to oxidative process. Additionally, inadequate conditions of storage result in the intensification of unfavorable processes. This problem is becoming more and more serious due to the high intensity of illumination of shop display cases and storage rooms, as well as the exposure to sunlight. Although literature data suggests that light may be an even more important oxidizing agent than oxygen, experiments are mainly focused on the oxidation progress in oils from varied raw materials or the changes in oil characteristics under different storage conditions. The aim of the study was to investigate the effect of the initial state of 30 commercial cold-pressed flaxseed oils on oxidative stability and oxidation product formation during storage under simulated store conditions (one-month at ambient temperature with light exposure). The oil quality was analyzed qualitatively (characteristic quality values, content of conjugated fatty acids, induction period, color parameters) and quantitatively (content of water and bioactive compounds, fatty acid composition). Oxidation progress in the oils was monitored by the characteristic quality values, content of conjugated fatty acids and color parameters.It was shown that commercially available cold-pressed flaxseed oils were generally good quality with similar color parameters and fatty acid composition, but mostly varied in terms of carotenoids, chlorophylls and phenolic compounds. Storage with light exposure caused the deterioration of the oil quality, and at least a 1.0-fold increase in acid and anisidine values and at least a 24.8-fold increase in peroxide value were determined. Also, the color of all oils changed after storage, and the calculated total color differences (ΔE) were in the range of 0.2–8.7. The results highlighted that the formation of oxidation products in flaxseed oil during storage in light resulted mainly from its initial quality indices. In turn, the induction period tested by Rancimat was dependent on the fatty acid percentages and total phenolic compound content. In conclusion, the Rancimat test is a poor indicator of the oxidative stability of oils under storage at ambient temperature with light exposure.

Effect of anti-oxidant additive on oxidation stability of biodiesel

Due to growth in population and lifestyle, energy consumption is also rapidly increasing with our everyday life. The demand for petroleum products is constantly increasing ever since it has been discovered and being a non-renewable resource, we have it in limited quantities. We are in need to discover an alternate fuel that can be used to replace petroleum products. Considering this, the use of biodiesel can be one of the possible solutions for the future energy demand if the properties of biodiesel can be matched with that of petroleum products, as biodiesel is a renewable and bio-degradable fuel. The biodiesel has been prepared by using Sesame oil and its oxidation stability has been tested with the help of the rancimat test. It has been attempted to increase the oxidation stability of the biodiesel by the addition of antioxidant additives and the most common additives like TBHQ and PY have been used. The research compares the effect of Diphenylamine (DPA) as an antioxidant additive with the results of other additives. And it has been observed that all three of the additives have an almost similar effect on oxidation stability.