Effect of heating on oxidation stability and fatty acid composition of microwave roasted groundnut seed oil

Regulation of Microlocalization of Antioxidants by Surfactant Micelles in Oil-in-Water Emulsions

The mass transport effect of aqueous micelles on antioxidants and oxidation products in emulsions may alter the rate, degree, and pathway of lipid oxidation. In this study, the dynamic mass transport of oxidation products and endogenous tocopherol during storage at different micelle concentrations was monitored by UV-vis spectrophotometry and high-performance liquid chromatography. Furthermore, the microlocalization of tocopherol in micelles was investigated using 1H nuclear magnetic resonance and nuclear Overhauser effect spectroscopy, fluorescence measurements, and molecular dynamics simulation. It was demonstrated that high-concentration micelles enhanced the emulsion stability by promoting the mass transport of hydroperoxides and endogenous antioxidants. The enhancement of micelles was a superposition effect of concentration, interaction sites, and binding force between tocopherols and Tween 20 molecules. Tween 20 concentration-induced favorable changes of microlocalization of tocopherol and dynamic mass transport demonstrated a new integrated perspective to control lipid oxidation.

Investigating the Thermal Stability of Omega Fatty Acid-Enriched Vegetable Oils

This study investigates the thermal stability of omega fatty acid-enriched vegetable oils, focusing on their behavior under high-temperature conditions commonly encountered during frying. This research aims to evaluate changes in fatty acid composition, particularly the degradation of essential omega-3, -6, and -9 fatty acids, and the formation of harmful compounds such as trans fatty acids (TFAs). Various commercially available vegetable oils labeled as containing omega-3, omega-6, and omega-9, including refined sunflower, high-oleic sunflower, rapeseed, and blends, were analyzed under temperatures from 180 °C to 230 °C for varying durations. The fatty acid profiles were determined using gas chromatography-mass spectrometry (GC-MS). The results indicated a significant degradation of polyunsaturated fatty acids (PUFAs) and an increase in saturated fatty acids (SFAs) and TFAs with prolonged heating. The findings highlight the varying degrees of thermal stability among different oils, with high-oleic sunflower and blended oils exhibiting greater resistance to thermal degradation compared to conventional sunflower oils. This study underscores the importance of selecting oils with favorable fatty acid compositions for high-temperature cooking to minimize adverse health effects associated with degraded oil consumption. Furthermore, it provides insights into optimizing oil blends to enhance thermal stability and maintain nutritional quality, crucial for consumer health and food industry practices.

Effects of adding green tea extract on the oxidative stability and shelf life of sunflower oil during storage

This study aimed to compare different concentrations effect of green tea extract (GTE) (200, 400, and 800 ppm) with TBHQ (75 ppm) in extend the shelf-life of sunflower oil (SO) and to evaluate the protective effect of GTE on the oxidation of refined SO. The sample's peroxide value (PV), acidity value (AV), anisidine value (pAV), Totox value (TV), oxidative stability, and total phenol content (TPC) were analyzed at specific intervals during 12-month at 25 °C and 60-day at 60 °C. The optimum kinetic model corresponding to the first order for PV, TV, and pAV was obtained at 25, 35, and 45 °C. SO containing GTE (800 ppm) had a similar performance to TBHQ at 25 °C and 60 °C and possessed a longer shelf life than samples treated with TBHQ. Due to synthetic antioxidant's health risk and toxicity, GTE can be a good substitute for TBHQ in the edible oil industry.

Lipid Oxidation and Volatile Compounds of Almonds as Affected by Gaseous Chlorine Dioxide Treatment to Reduce Salmonella Populations

The effects of gaseous chlorine dioxide (ClO₂) treatment, applied to inactivate Salmonella, on lipid oxidation, volatile compounds, and chlorate levels of dehulled almonds were evaluated during a 3 month accelerated storage at 39 °C. At treatment levels that yielded a 2.91 log reduction of Salmonella, ClO₂ promoted lipid oxidation as indicated by increased peroxide values, total acid number, conjugated dienes, and thiobarbituric acid-reactive substances. Furthermore, several chlorine-containing volatile compounds including trichloromethane, 1-chloro-2-propanol, 1,1,1-trichloro-2-propanol, and 1,3-dichloro-2-propanol were identified in ClO₂-treated samples. However, all the volatile chlorine-containing compounds decreased during the 3 months of storage. Chlorate (26.4 ± 5.1 μg/g) was found on the ClO₂-treated samples. The amounts of non-ethanol alcohols, aldehydes, and carboxylic acids increased following ClO₂ treatments. Some volatiles such as 2,3-butanediol that were present in non-treated samples became non-detectable during post-ClO₂ treatment storage. Overall, our results demonstrated that gaseous ClO₂ treatment promoted lipid oxidation, generation of volatiles of lipid origin, and several chlorine-containing compounds.

Experimental investigation of different-shaped microwave-heated potatoes: thermal and quality characteristics analysis for food preservation

Food materials are consumed for nutritional purposes in the form of fruits, vegetables, plants, and meat. These contain proteins, carbohydrates, and other useful nutritional compounds and these processed foods are a rich source of nutrition. The demand and supply of hygienic food for a particular population is possible only by food preservation. It can be done by various methods such as drying, freezing, chilling, chemical preservation, and pasteurization. Drying is a method of food preservation and it can be done by solar drying, microwave heating, vacuum drying, and some other methods. Microwave heating is a fast-drying method. It utilizes electrical energy to generate heat energy. The domestic microwave oven is not harmful but a commercial-level oven may be little bit harmful, when operated on high frequency. Potato is used as a sample material with different shapes such as slab, cylindrical, and spherical. The microwave oven has been operated at four different microwave powers such as 100 W, 300 W, 600 W, and 800 W. Slab-shaped (30 °C), cylindrical-shaped (31.5 °C), and spherical-shaped (30.5 °C) food materials achieved maximum temperatures of 83.9 °C, 110.6 °C, and 146.1 °C respectively. The temperature variations and drying characteristics of the food samples have been monitored. An oven has achieved maximum drying efficiency of 25.65% with a slab-shaped sample. For the detection of the cracks and chemical compositions in the food samples, SEM with EDS analysis has been performed. Economic analysis of microwave oven has also been done and payback period has been found as 3.27 years.

Changes in Chemical Composition of Flaxseed Oil during Thermal-Induced Oxidation and Resultant Effect on DSC Thermal Properties

To investigate the changes in chemical composition of flaxseed oil during thermal-induced oxidation and the resultant effect on thermal properties, samples with different oxidation levels were obtained by being heated at 180 °C for two hours and four hours. The oxidation degree was evaluated using peroxide value (PV), extinction coefficient at 232 nm and 268 nm (K232 and K268), and total polar compounds (TPC). Using chromatography, the fatty acid profile and triacylglycerol (TAG) profile were examined. Differential scanning calorimetry (DSC) was used to determine the crystallization and melting profiles. Thermal-induced oxidation of flaxseed oil led to a significant increase (p < 0.05) in PV, K232, K268, and TPC, but the relative content of linolenic acid (Ln) and LnLnLn reduced dramatically (p < 0.05). TPC derived from lipid degradation affected both crystallization and melting profiles. Statistical correlations showed that the onset temperature (Ton) of the crystallization curve was highly correlated with K232, TPC, and the relative content of LnLnLn (p < 0.05), whereas the offset temperature (Toff) of the melting curve was highly correlated with the relative content of most fatty acids (p < 0.05). This finding provides a new way of rapid evaluation of oxidation level and changes of chemical composition for flaxseed oils using DSC.

The effect of roasting, storage temperature, and ethanoic basil (Ocimum basilicum L.) extract on the oxidative stability of crude sesame (Sesamum indicum L.) oil

Sesame (Sesamum indicum L.) is an annual oilseed crop that is widely used for crude sesame oil (CSO) extraction. CSO is unrefined, thus, may impact the storage stability due to the uncontrolled processing and handling conditions, and absence of preservatives. The purpose of this study intends to analyze the fatty acid profile and oxidative stability of CSO. In a complete randomized (2*2*2) factorial design, clean sesame seeds (3.92% moisture content) were used for oil extraction with/without roasting treatment (200°C). The fatty acid profile and oxidative value of the CSO were analyzed. The roasted sesame seed oil extraction yield was higher (50.9%) and composed of 83.15% unsaturated fatty acids with an omega-6 to omega-3 ratio of 95.3. The ratio of polyunsaturated fatty acids (PUFAs) to saturated fatty acids (SFAs) was 2.9, while the moisture content of the CSO was 0.37%, exceeding the tolerable limit. The predominant fatty acids of CSO include palmitic, stearic, oleic, and linoleic acids. Elevated thermal condition during processing and handling speeding up oxidation exceeded the tolerable limit after 25 days of storage, while the ethanoic basil extract was found to inhibit oxidation in the range of 16.38%-90% (p-value < .05). The peroxide value (PV), para-anisidine value (p-AV), and total oxidation (TOTOX) value of CSO with 50 ppm (parts per million) basil extract were detected within the range of 0.29-3.92, 0.75-2.59, and 1.57-8.6 milliequivalents (meq) O2/kg oil, respectively, below the tolerable limit. Nevertheless, basil extract's antioxidant property was declined during prolonged storage, in particular, at elevated temperature. The use of organic extracts of locally available sweet basil herb is capable of mitigating oxidation and substituting inorganic antioxidant for a healthier diet.

Vegetable oils composition affects the intestinal lymphatic transport and systemic bioavailability of co-administered lipophilic drug cannabidiol

Although natural sesame oil has been shown to facilitate the lymphatic delivery and oral bioavailability of the highly lipophilic drug cannabidiol (CBD), considerable variability remains an unresolved challenge. Vegetable oils differ substantially in composition, which could lead to differences in promotion of intestinal lymphatic transport of lipophilic drugs. Therefore, the differences in composition of sesame, sunflower, peanut, soybean, olive and coconut oils and their corresponding role as vehicles in promoting CBD lymphatic targeting and bioavailability were investigated in this study. The comparative analysis suggests that the fatty acids profile of vegetable oils is overall similar to the fatty acids profile in the corresponding chylomicrons in rat lymph. However, arachidonic acid (C20:4), was introduced to chylomicrons from endogenous nondietary sources. Overall, fatty acid composition of natural vegetable oils vehicles affected the intestinal lymphatic transport and bioavailability of CBD following oral administration in this work. Olive oil led to the highest concentration of CBD in the lymphatic system and in the systemic circulation in comparison to the other natural vegetable oils following oral administration in rats.

Effect of Natural Antioxidants from Marigolds (Tagetes erecta L.) on the Oxidative Stability of Soybean Oil

In recent years, synthetic antioxidants that are widely used in foods have been shown to cause detrimental health effects, and there has been growing interest in antioxidants realised from natural plant extracts. In this study, we investigate the potential effects of natural antioxidant components extracted from the forage plant marigold on the oxidative stability of soybean oil. First, HPLC-Q-TOF-MS/MS was used with 1,1-diphenyl-2-picrylhydrazyl (DPPH) to screen and identify potential antioxidant components in marigold. Four main antioxidant components were identified, including quercetagetin-7-O-glucoside (1), quercetagetin (2), quercetin (3) and patuletin (4). Among them, quercetagetin (QG) exhibited the highest content and the strongest DPPH radical scavenging activity and effectively inhibited the production of oxidation products in soybean oil during accelerated oxidation, as indicated by reductions in the peroxide value (PV) and acid value (AV). Then, the fatty acids and volatile compounds of soybean oil were determined with gas chromatography–mass spectrometry (GC-MS) and headspace solid-phase microextraction–gas chromatography–mass spectrometry (HS-SPME-GC-MS). A total of 108 volatile components, including 16 alcohols, 23 aldehydes, 25 ketones, 4 acids, 15 esters, 18 hydrocarbons, and 7 other compounds, were identified. QG significantly reduced the content and number of aldehydes and ketones, whereas the formation of acids and hydrocarbons was completely prevented. In addition, the fatty acid analysis demonstrated that QG significantly inhibited oxidation of unsaturated fatty acids. Consequently, QG was identified as a potential, new natural antioxidant that is believed to be safe, effective and economical, and it may have potential for use in plant extracts feed additives.

Physicochemical Characterization of Quinoa (Chenopodium quinoa cv. Nariño) Co-products Obtained by Wet Milling

In recent years, great interest has been shown in pseudocereals for their high nutritional value. Wet milling has been used to obtain macromolecules such as proteins and starches. However, the co-products obtained from this food industry have been studied little. A factorial design Box-benhken was used to study the effect of surfactant concentration (SDS), sodium hydroxide (NaOH) concentration and maceration temperature on structural and colorimetric properties. Structural properties were evaluated by infrared spectroscopy (FTIR-ATR) and color changes by the CIElab tristimulus method (L*, a*, b*). A decrease in temperature and NaOH causes a decrease in lightness (L*), resulting in lower starch content and higher protein content in the co-product. This behavior was correlated with the infrared spectroscopy (FTIR-ATR) spectra. The spectra show a possible structural change in the amylose/amylopectin ratio of the starch granule at 1,012 cm−1, 1,077 cm−1, and 1,150 cm−1 bands, which are associated with glycosidic bonds, these bonds were sensitive to NaOH concentration. While those bands assigned to Amide II (1,563 cm−1) and Amide I (1,633 cm−1), were sensitive to the effect of NaOH and maceration temperature, evidencing that protein content in the co-products is variable and depends significantly on the extraction conditions. The co-products obtained by wet milling could be used in the development of functional foods, such as bread, snacks, pasta and other products.

Black mahlab (Monechma ciliatum L.) seeds: processing effects on chemical composition and nutritional value

Introduction. Monechma ciliatum L. seeds are rich in proteins, carbohydrates, oils and mineral contents. Researchers have focused on new production development but there is no available data on the impact of processing techniques on the quality of the seeds. Our study aimed to investigate the impact of boiling, roasting, and germination on the composition and nutritional value of Monechma ciliatum (black mahlab) seeds. Study objects and methods. We analyzed 7 kg of black mahlab seeds purchased from the local market. We applied standard methods used in boiling, roasting, and germination techniques. Proximate analyses were performed using the methods of the Association of Official Analytical Chemists. Minerals were analyzed by inductively coupled plasma-mass spectrometry (ICP-MS), and fatty acids were determined by gas chromatography. Tocopherols and amino acids in processed seeds were determined by high-performance liquid chromatography. Results and discussion. The results showed that the proximate compositions of untreated, boiled, roasted, and germinated mahlab seeds were affected by boiling, roasting, and germination techniques. Most of the nutritional values were enhanced by all the treatments. In particular, all the processing techniques increased the protein content. Boiling and roasting increased the fat content, while boiling and germination increased the fiber content. Tocopherols were higher only in the germinated samples. Amino acids were increased by all the techniques. Minerals were affected by all the techniques, except for Na, which was higher in the germinated sample. Conclusion. Boiling, roasting, and germination enhanced significantly the chemical composition of Monechma ciliatum seeds, which make them a value ingredient to develop new food products.

Goji Berry (Lycium Barbarum L.) Carotenoids Enrichment through ‘Green’ Extraction Method Improves Oxidative Stability and Maintains Fatty Acids of Yak Ghee with Microwave Heating and Storage

As the oxidation of yak ghee is inevitable and as consumer demand for natural products continues to increase, this study aimed to enrich yak ghee with goji berry carotenoids by means of green solvent extraction and determined changes in the oxidative stability and fatty acid profiles of yak ghees during microwave heating (MW-heating) and accelerated storage. An enriched ghee (GG0) was prepared by high shear dispersion and ultrasound-assisted extraction, while a control ghee (FG0) was prepared by heating and filtration; both ghees were stored at 65 °C for 30 days and were microwave-heated (MW-heating) at 180 °C (15 and 30 min) and 200 °C for 30 min. The results showed that the carotenoid enrichment increased the oxidative stability of yak ghee during MW-heating and storage. The initial CLA and PUFA values of GG0 were not significantly different from those of FG0; SFA increased, and MUFA and TFA decreased. There was a faster rate of UFA loss and an increase in SFA and TFA in FG0 during MW-heating and storage. This indicated a protective effect of carotenoid enrichment on yak ghee. Therefore, the findings in this study support the use of goji berry carotenoids as a natural colorant and antioxidant in yak ghee. This study provides vital information for dairy processors and marketers.

Novel seeds pretreatment techniques: effect on oil quality and antioxidant properties: a review

Seed oil quality is a function of several attributes which include its bioactive compounds, physicochemical and functional properties. These quality attributes are important in seed oil processing as they determine the oil palatability, nutritional and market value. Besides the health, environmental and economic issues related to seed oil extraction using organic solvents such as hexane, other conventional seed oil extraction techniques such as supercritical fluid extraction, enzyme digestion and cold pressing are associated with low recovery of oil and bioactive compounds. Application of novel seeds pretreatments techniques such as microwaving, enzymatic digestion, pulsed electric field and ultrasonication do not only improve the oil yield and quality attributes, but also reduces seed oil extraction time, solvent and energy consumption. Higher phenolic compounds, carotenoids, tocopherols, phytosterols and antioxidant properties in oil from pretreated seeds offer health benefits related to the prevention of cancer, diabetes, obesity, inflammatory and cardiovascular diseases. Increased consumer interest in functional foods and the potential of seeds pretreatments in enhancing the extractability of bioactive compounds from plant material has increased the application of novel pretreatment techniques on diverse oilseeds. This review describes the commonly studied novel seeds pretreatment techniques and critically discusses their influence on the oil physicochemical attributes, oxidation indices, bioactive compounds and antioxidant properties.

Efficient Production of Dried Whole Peanut Fruits Based on Infrared Assisted Spouted Bed Drying

The present study is designed to evaluate the effect of infrared assisted spouted bed drying (IR-SBD) on the product quality and energy consumption of whole peanut fruits (including peanut kernels and shells). The dehydration of whole peanuts by means of hot-air drying (HD) and infrared drying (ID) were used as the control groups, and the drying characteristics, energy consumption, microstructure, porosity, hardness and fatty acid content were compared. The results showed that, compared to HD and ID, IR-SBD could reduce the drying time by 40% and 33%, respectively, and reduced energy consumption by 66% and 32%, respectively. During the drying process, the structures of both the peanut shells and peanut kernels underwent significant deformation; specifically, the porosity gradually increased gradually. The maximum porosity value was obtained by the samples dried by means of IR-SBD. Under the three drying conditions, the hardness of the peanut shells first decreased and then increased, while the hardness of the peanut kernels showed a trend of first increasing, then decreasing and finally increasing. Compared to the fresh whole peanuts, the IR-SBD dried samples exhibited a 4.07% decrease in fatty acid. This study shows that IR-SBD is a suitable application for the dehydration process of whole peanuts for the purposes of achieving high-efficiency and -quality production in the industrial sector.

Physicochemical Properties, Fatty Acid Composition, and the Effect of Heating on the Reduction of Cyclopropenoid Fatty Acids on Baobab (Adansonia digitata L.) Crude Seed Oil

The baobab seed oil has been consumed by humans due to its medicinal and nutrient values for many years. However, the consumption of baobab seed oil has been perceived by different communities as a health risk caused by cyclopropenoid fatty acids (CPFAs), which are carcinogenic ingredients present in the oil. This study investigated the physicochemical properties and fatty acid profile of baobab crude seed oil collected from semiarid areas in Tanzania and determined the effects of heating on the reduction of CPFAs. The baobab seed crude oil was extracted by Soxhlet using n-hexane, and the fatty acid composition of the baobab seed crude oil was determined by gas-liquid chromatography (GLC). Since CPFAs are resistant to lower temperatures, the effect of heating on the CPFA content of baobab crude seed oil was studied at 150°C, 200°C, and 250°C. The A. digitata crude seed oil was found to contain mainly twelve essential fatty acids and two different CPFAs. The most abundant fatty acids were palmitic acid, oleic acid, and linoleic acid in all the baobab population hotspots occurring in Tanzania. There was no significant difference in most physicochemical properties and fatty acid composition across the different semiarid areas in Tanzania. The major breakdown of CPFAs occurs at 200°C, and that would be the optimal temperature recommended for the refining process of the baobab crude oil. The study recommended refining of the baobab oil at higher temperatures ranging from 200 - 250°C as the best way of reducing CPFAs.

Influence of Thermal Processing on Oil Contents, Bioactive Properties of Melon Seed and Oils

The oil content and the fatty acid composition of roasted and unroasted melon seed and oils were determined. The oil contents of roasted melon seeds changed between 26.4% (Type 12) and 38.7% (Type 4). In general, oil contents of roasted melon seeds were found higher than that of unroasted seeds that could be due to the evaporation of water during roasting processes which consequently lead to increased concentrations of other seed components including oils. Saturated fatty acid contents of unroasted melon seed samples change between 13.5% (Type 6) and 17.1% (Type 20). In addition, polyunsaturated fatty acids of unroasted melon seed oils ranged from 51.9% (Type 13) to 70.2% (Type 6). Palmitic acid contents of roasted seed oils varied between 7.8% (Type 5) and 15.1% (Type 17). In addition, the oleic acid contents ranged from 15.4% (Type 10) to 37.7% (Type17). Also, linoleic acid contents were found between 34.7% (Type 17) and 70.3% (Type 6). Saturated fatty acid contents of roasted melon seed oils ranged from 13.5% (Type 6) to 16.7% (Type 13). The major tocopherols in both roasted and unroasted melon seed oils were α-tocopherol, ɣ-tocopherol and δ-tocopherols. Melon seed oils are rich in linoleic, oleic acids and ɣ-tocopherol.

Oxidative Stability of Protease Treated Peanut with Reduced Allergenicity

Oxidative stability and allergenicity are two major concerns of peanuts. This study evaluated the impact of protease treatment of peanuts on its oxidative stability during storage. The raw and dry-roasted peanut kernels were hydrolyzed with Alcalase solution at pH 7.5 for 3 h. The contents of Ara h 1, Ara h 2, and Ara h 6 in peanuts were determined before and after enzyme treatment by a sandwich ELISA. After drying, the samples were packed in eight amber glass jars and stored at 37 °C for 1-8 weeks. Controls are untreated raw and dry-roasted peanuts packed and stored in the same way as their treated counterparts. Samples were taken biweekly to determine peroxide value (PV) and thiobarbituric acid reactive substances (TBARS) as indicators of oxidation (n = 3), and to determine antioxidant activity. Alcalase treatment reduced intact major allergens Ara h 1, Ara h 2, and Ara h 6 by 100%, 99.8%, and 85%, respectively. The PVs of Alcalase-treated raw and roasted peanuts was lower than those of untreated (p < 0.05) over the 8-week storage. The TBARS of Alcalase-treated raw peanuts were slightly higher than that of untreated (p < 0.05), but the TBARS of Alcalase-treated dry-roasted peanuts were slightly but significantly lower than that of untreated (p < 0.05). The protease treatment increased the antioxidant activities including reducing power, DPPH free radical scavenging capacity, and metal chelating capacity of peanuts.

Compositional heterogeneity confers selective advantage to model protocellular membranes during the origins of cellular life

Protocellular membranes are thought to be composed of mixtures of single chain amphiphiles, such as fatty acids and their derivatives, moieties that would have been part of the complex prebiotic chemical landscape. The composition and physico-chemical properties of these prebiological membranes would have been significantly affected and regulated by their environment. In this study, pertinent properties were systematically characterized, under early Earth conditions. Two different fatty acids were mixed with their respective alcohol and/or glycerol monoester derivatives to generate combinations of binary and tertiary membrane systems. Their properties were then evaluated as a function of multiple factors including their stability under varying pH, varying Mg²⁺ ion concentrations, dilution regimes, and their permeability to calcein. Our results demonstrate how environmental constraints would have acted as important prebiotic selection pressures to shape the evolution of prebiological membranes. The study also illustrates that compositionally diverse membrane systems are more stable and robust to multiple selection pressures, thereby making them more suitable for supporting protocellular life.

Effect of Heating on Compositional Characteristics and Oxidative Stability of Crude and Refined Rice Bran Oil

The compositional characteristics and oxidative stability of rice bran oil were determined by observing the formation of oxidative products and alteration in chemical composition of oils during microwave or oven heating. The values of oxidative indicators such as free acidity, peroxide, p-anisidine, total oxidation, thiobarbituric acid and color values, increased faster in refined oils compared to crude ones during heating. In gas chromatography analysis, the percentages of total saturated, monounsaturated and polyunsaturated fatty acids in the studied oils such as lab extracted crude rice bran oil, lab extracted and refined rice bran oil, crude rice bran oil from commercial mill and refined rice bran oil from commercial mill were: 23.07 to 23.56, 41.15 to 42.38 and 34.38 to 35.88, respectively. The heating caused the reduction of polyunsaturated fatty acids content with increasing saturated fatty acids content, and these changes were greater in refined rice bran oil indicating extensive lipid oxidation occurred in refined oil. The change in triacylglycerol species content as determined by High-performance liquid chromatography, was lower in crude oil; the higher stability of these species in crude oil could have contribution to reduce oxidation. During thermal treatment, the generation of hydroperoxides, their degradation and formation of secondary oxidative products evaluated by Fourier-transform infrared spectroscopy, were lower in crude oils. However, the rate of formation of oxidative products in lab prepared samples was lower compared to that in the samples collected from commercial mill. Under extreme thermal condition, the order of oxidative stability: lab extracted crude rice bran oil > crude rice bran oil from commercial mill>lab extracted and refined rice bran oil > refined rice bran oil from commercial mill. The present results will be useful to oil seed processing mills in refining of rice bran oil for economic feasibility and better marketability.

Impact of roasting and extraction methods on chemical properties, oxidative stability and Maillard reaction products of peanut oils

This study was designed to investigate the influence of dry air roasting (140, 160 and 180 °C for 5 and 10 min) and extraction methods (solvent and mechanical) on peanut oil quality characteristics. Oil yield, oxidative stability index (OSI), radical scavenging activity (RSA), and Maillard reaction products were increased while peroxide value (PV) and conjugated dienes were decreased in oil of peanuts roasted at 180 °C for 10 min. Oils extracted mechanically from roasted peanuts had lower PV while higher OSI and RSA than the solvent-extracted oils. The fatty acid composition of oils from roasted peanuts (at 160 and 180 °C for 10 min) changed slightly compared to unroasted peanuts. The level of 5-hydroxymethylfurfural and non-enzymatic browning index was significantly increased in oil from peanuts roasted at 180 °C for 10 min. FTIR spectra showed a slight change in peak intensities with no observed peak shift in oils extracted from peanuts roasted at 180 °C for 10 min. Based on the results obtained, mechanically extracted oil from peanuts roasted at 180 °C for 10 min improves oil quality characteristics and enhances oxidative stability.

Nutritional quality of almond, canarium, cashew and pistachio and their oil photooxidative stability

Daily consumption of nuts is recommended as a part of a healthy diet as they contain protein and are rich in beneficial fatty acids and essential nutrients. The nutritional qualities of nuts are affected by their fatty acid composition and other factors such as maturity. Oil oxidative stability is important to determine nut nutritional quality in terms of fatty acid composition over storage. Therefore, this study aimed to (a) assess the nutritional quality (photooxidative stability and nutrient composition) of almond, cashew, pistachio and canarium (a newly commercialised indigenous nut); and (b) explore differences in nutrient concentrations between immature and mature canarium nuts. A decrease in polyunsaturated fats after photooxidation in almond and pistachio was observed. Canarium oil did not change following photooxidation suggesting canarium may display a long shelf life when stored appropriately. Our study indicated that almond provided over 50% of the recommended daily intake for manganese whereas canarium intake provided 50% of the recommended daily intake for iron (for males). Pistachio was richer in potassium compared with other nuts and canarium was richer in boron, iron and zinc than other nut species. Mature canarium kernels were richer in boron, iron and zinc but contained less potassium than immature canarium. Therefore, the current study recommended to store kernels in dark to decrease oil photooxidation, and maturity of canarium kernels at the harvest time was important affecting nutrient concentrations of kernels.