Effect of radio frequency roasting on the lipid profile of peanut oil and the mechanism of lipids transformation: Revealed by untargeted lipidomics approach.

Radio frequency (RF) heating has been proved an alternative roasting method for peanuts, which could effectively degrade aflatoxins and possesses the advantages of greater heating efficiency and penetration depth. This study aimed to investigate the influences of RF roasting on the lipid profile of peanut oil under 150 °C target temperature with varied peanut moisture contents (8.29 % and 20 %) and holding times (0, 7.5, and 15 min), using ultra-performance liquid chromatography-quadrupole time-of-flight tandem mass spectrometry (UPLC-QTOF-MS/MS)-based lipidomics. In total, 2587 lipid species from 35 subclasses were identified. After roasting, the contents of sterol lipid (ST) and subclasses of glycerophospholipids (GPs) and glycoglycerolipids increased significantly, while fatty acid (FA), Oxidized (Ox-) FA, cholesterol (CE), and all subclasses of glycerolipids (GLs) decreased, and 1084 differential lipids were screened. The highest ST and lowest CE contents in peanut oil were achieved by medium roasting (7.5 min). The raise in moisture content of peanut simply affected a few GPs subclasses adversely. Compared with hot air (HA) roasting, RF decelerated lipid oxidation, showing higher levels of diacylglycerol, triacylglycerol and FA, with no additional negative impact and only 69 exclusive differential lipids. During RF roasting, hydrolysis and oxidation of fatty acyl chains into secondary oxides were the central behaviors of lipids transformation. This study could provide insights into the lipid changes and transformation mechanism of peanut oil by RF roasting processing.

A smartphone-enabled visual platform for detecting aflatoxins in peanut oil using colorimetric analysis coupled with magnetic imprinted solid-phase extraction.

The study aimed to develop a rapid and sensitive colorimetric platform based on the Emerson reaction to visualize and determine total aflatoxins (AFs) in peanut oil. This method offers the advantage of fast screening for AFs (AFB1, AFB2, AFG1, and AFG2), eliminating the need for specific antibodies. The proposed approach combined colorimetric detection with magnetic dummy imprinted solid-phase extraction and purification, enhancing sensitivity and selectivity. The oxidizer aided the colorless AFs in reacting with 4-aminoantipyrine, producing green condensates. Thus, a dual-mode approach was developed for AFs detection, employing both UV-vis colorimetric and smartphone-based colorimetry. Both methods showed a good linear relationship with the concentration of AFs. Notably, the smartphone-based method demonstrated a detection range of 0.5-57 µg/kg, with a detection limit as low as 0.21 µg/kg. The suggested colorimetric methods present a promising potential for onsite detection and fast screening of AFs in actual samples.

Characterization of Key Aroma Compounds and Main Contributing Amino Acids in Hot-Pressed Oil Prepared from Various Peanut Varieties.

The production of peanut oil in the industrial sector necessitates the utilization of diverse raw materials to generate consistent batches with stable flavor profiles, thereby leading to an increased focus on understanding the correlation between raw materials and flavor characteristics. In this study, sensory evaluations, headspace solid-phase micro-extraction gas chromatography mass spectrometry (HS-SPME-GC-MS), odor activity value (OAV) calculations, and correlation analysis were employed to investigate the flavors and main contributing amino acids of hot-pressed oils derived from different peanut varieties. The results confirmed that the levels of alcohols, aldehydes, and heterocyclic compounds in peanut oil varied among nine different peanut varieties under identical processing conditions. The OAVs of 25 key aroma compounds, such as methylthiol, 3-ethyl-2,5-dimethylpyrazine, and 2,3-glutarone, exceeded a value of 1. The sensory evaluations and flavor content analysis demonstrated that pyrazines significantly influenced the flavor profile of the peanut oil. The concentrations of 11 amino acids showed a strong correlation with the levels of pyrazines. Notably, phenylalanine, lysine, glutamic acid, arginine, and isoleucine demonstrated significant associations with both pyrazine and nut flavors. These findings will provide valuable insights for enhancing the sensory attributes of peanut oil and selecting optimal raw peanuts for its production.

Effect of starch and peanut oil on physicochemical and gel properties of myofibrillar protein: Amylose content and addition form.

Starch and peanut oil (PO) were widely used to improve the gel properties of surimi, however, the impact mechanism of addition forms on the denaturation and aggregation behavior of myofibrillar protein (MP) is not clear. Therefore, the effect of starch, PO, starch/PO mixture, and starch-based emulsion on the physicochemical and gel properties of MP was investigated. The results showed that amylose could accelerate the aggregation of MP, while amylopectin was conducive to the improvement of gel properties. The addition of PO, starch/PO mixture, or starch-based emulsion increased the turbidity, solubility, sulfhydryl content of MP, and improved the gel strength, whiteness, and texture of MP gel. However, compared with starch/PO mixture group, the gel strength of MP with waxy, normal and high amylose corn starch-based emulsion increased by 22.68 %, 10.27 %, and 32.89 %, respectively. The MP containing emulsion had higher storage modulus than MP with starch/PO mixture under the same amylose content. CLSM results indicated that the oil droplets aggregated in PO or starch/PO mixture group, while emulsified oil droplets filled the protein gel network more homogeneously. Therefore, the addition of starch and PO in the form of emulsion could effectively play the filling role to improve the gel properties of MP.

One-pot green synthesis of ZIF-8/IgG composite for the precise orientation and protection of antibody and its application in purification and detection of aflatoxins in peanut oil.

This study presents a novel approach toward the one-pot green synthesis of ZIF-8/IgG composite, focusing on its precise orientation and protection of the anti-aflatoxins antibody. The antibody orientation is achieved through the specific binding of IgG to the Fc region of the antibody, while the antibody protection is accomplished by the structural change restriction of ZIF-8 framework to the antibody. Consequently, the antibody exhibits enhanced target capability and significantly improved tolerance to organic solvents. The ZIF-8/IgG/anti-AFT was employed for the purification and detection of AFTs by coupling with UPLC. Under optimized conditions, the recoveries of spiked AFTs in peanut oils are between 86.1% and 106.4%, with relative standard deviations (RSDs) ranging from 0.8% to 8.8%. The linearity range is 0.5-20.0 ng for AFB1 and AFG1, 0.125-5.0 ng for AFB2 and AFG2, the limit of detection is 0.1 ng for AFB1 and AFG1, 0.03 ng for AFB2 and AFG2.

Effects of Pretreatment on Stability of Peanut Oil Bodies and Functional Characteristics of Proteins Extracted by Aqueous Enzymatic Method.

Effects of dry and wet grind on peanut oil and protein yield, oil bodies (OBs) stability, fatty acid composition, protein composition and functional characteristics were systematically analyzed. Results showed that peanut oil and protein yields reached highest at dry grind 90 s (92.56% and 83.05%, respectively), while peanut oil and protein yields were 94.58% and 85.36%, respectively, at wet grind 120 s. Peanut oil and protein yields by wet grind was 2.18% and 2.78% higher than that of dry grind, respectively. Surface protein concentration (Г) and absolute value of zeta potential of OBs extracted by wet grind (WOBs) were 11.53 mg/m 2 and 18.51 mV, respectively, which were higher than OBs extracted by dry grind (DOBs), indicating stability of WOBs was higher than DOBs. Relative contents of oleic acid and linoleic acid in peanut oil, essential and hydrophobic amino acids in protein extracted by wet grind were higher than dry grind. There was little difference in protein composition between wet and dry grind, but thermal denaturation degree of protein obtained by wet grind was lower than dry grind. Solubility, oil retention, emulsion stability, foaming and foam stability of protein obtained by wet grind were better than dry grind. Results from this study provided theoretical basis for grind pretreatment selection of aqueous enzymatic method.

Contribution of lipid to the formation of characteristic volatile flavor of peanut oil.

Lipid is an important precursor for volatile flavor formation, but it is not clear how to study the reactions involved in forming key volatile flavor compounds in peanut oil. In this paper, we innovatively established a flavor research model to investigate the contribution of different chemical reactions to the aroma compounds of peanut oil. The results showed that lipid participation in thermal reactions is necessary for forming major aroma compounds in hot-pressed peanut oil. Compared to the Maillard reaction, the lipid oxidation-Maillard reaction produces more compounds with 46 volatile substances identified. During the heating process, six new key substances were formed and the level of unsaturated fatty acids decreased by 7.28%. Among them, linoleic acid may be an important precursor for the formation of aroma components of hot-pressed peanut oil. Our study could provide theoretical guidance for understanding the volatile flavor mechanism of peanut oil and improving volatile flavor.

Green process for the preparation of resveratrol-containing high oleic acid peanut oil.

Resveratrol (Res), a polyphenol compound with strong biological activity, is widely used in medicinal and health products. In this study, an innovative resveratrol high oleic peanut oil (Res-HOPO) was prepared utilizing self-developed cold pressing equipment and high oleic peanuts. The peanut roots were pretreated with four different methods, including ultra-fine crushing, ultrasound-treating, microwave-treating, and a combination of microwave-ultrasound-treating peanut roots. Under optimized conditions (microwave power of 15 W, ultrasound time of 28 min, and ultrasound power of 400 W), the Res-HOPO prepared by pretreating with a combination of microwave-ultrasound had the most Res (91.12 mg/kg). Except for the pretreated whole peanut roots, pretreating with microwave (40.49 mg/kg), ultrasound (39.03 mg/kg), and ultra-fine crushing of peanut root powder (22.57 mg/kg) resulted in the high Res content. The Res-HOPO had a satisfactory yield (40%), oleic acid content (74.05% ∼ 75.85%), no trans fatty acids, great physicochemical properties, higher nutritional value (4-fold increase in squalene and almost 10-fold increase in campesterol), an extended oxidation induction time (1.39 âˆ¼ 22 times), and no heavy metals, pesticides, or aflatoxins. The four green pretreatment methods used for the preparation of Res-HOPO in this study were effective, which provided an innovative approach for developing nutritious and healthy edible oil.

Effects of Extraction Methods on the Bioactivities and Nutritional Value of Virginia and Valencia-Type Peanut Oil.

This study aimed to evaluate the effects of peanut varieties cultivated in Morocco (Virginia and Valencia) and extraction methods (cold press, CP; Soxhlet, Sox and maceration, and Mac) on the fatty acid profile, phytosterol, and tocopherol contents, quality characteristics, and antioxidant potential of peanut seed oil. The DPPH method was used to determine the antioxidant activity of the oils. The results revealed that fatty acid content was slightly affected by the extraction technique. However, the CP method was shown to be an excellent approach for extracting oil with desirable quality features compared to the Sox and Mac methods. Furthermore, the peanut oil extracted via CP carried a higher amount of bioactive compounds and exhibited remarkable antioxidant activities. The findings also revealed higher oleic acid levels from the Virginia oil, ranging from 56.46% to 56.99%. Besides, a higher total phytosterol and tocopherol content and DPPH scavenging capacity were obtained from the Valencia oil. Analyzing the study, it can be inferred that extraction method and variety both affect the composition of the peanut oil's bioactive compounds and antioxidant activity. This information is relevant for extracting peanut oil with a greater level of compounds of industrial interest.

Synthesis of Rice Husk-Based MCM-41 for Removal of Aflatoxin B1 from Peanut Oil.

Edible oils, especially peanut oil, usually contain aflatoxin B1 (AFB1) at extremely high concentrations. This study focused on the synthesis of rice husk-based mesoporous silica (MCM-41) for the removal of AFB1 from peanut oil. MCM-41 was characterized by X-ray diffraction, N2 physisorption, and transmission electron microscope. MCM-41 was shown to have ordered channels with high specific surface area (1246 m2/g), pore volume (1.75 cm3/g), and pore diameter (3.11 nm). Under the optimal concentration of 1.0 mg/mL of the adsorbent dose, the adsorption behavior of MCM-41, natural montmorillonite (MONT), and commercial activated carbon (CA) for AFB1 were compared. The adsorption of AFB1 in peanut oil onto the three adsorbents was slower compared to that of AFB1 in an aqueous solution. In addition, the pseudo-second-order kinetic model better fit the adsorption kinetics of AFB1, while the adsorption mechanism followed the Langmuir adsorption isotherm on the three adsorbents. The calculated maximum adsorbed amounts of AFB1 on MONT, MCM-41, and CA were 199.41, 215.93, and 248.93 ng/mg, respectively. These results suggested that MCM-41 without modification could meet market demand and could be considered a good candidate for the removal of AFB1 from peanut oil. This study provides insights that could prove to be of economic and practical value.

Effect of Drying Methods on Peanut Quality during Storage.

Storage is an important step after peanut harvest and drying. Many factors could affect the peanut quality during storage. The quality change differences of peanut after being dried by solar radiation and at 35°C, 40°C, 45°C, 50°C during later storage were investigated, including moisture content (MC) and germination percentage (GP) of peanut kernels, acid value (AV), peroxide value (PV), iodine value (IV), vitamin E (VE) content and fatty acid composition (FAC) of extracted peanut oil. And the impact of four storage conditions, air-room temperature (A-RT), air-low temperature (A-LT), vacuum-room temperature (V-RT) and nitrogen-room temperature (N-RT) on peanut quality after 10 months' storage were also studied in this paper. The results revealed that drying conditions had only a little influence on peanut quality during later storage. Peanut dried by solar radiation was more easily oxidized than that dried under other drying conditions. The effects of storage time were much greater. The GP, AV, PV, VE content and FAC, showed significantly changes along with storage. GP and VE content decreased, AV and PV increased, and some linoleic acid was oxidized to oleic acid after 10 months' storage. In addition, A-LT exhibited best performance in keeping peanut quality than A-RT, V-RT and N-RT, which demonstrated that low temperature was more advantageous for peanut storage than controlled atmosphere. These results above would provide useful information and reference for the peanut storage to apply in food industry.

Headspace Solid-Phase Microextraction Analysis of Volatile Components in Peanut Oil.

Peanut oil is favored by consumers due to its rich nutritional value and unique flavor. This study used headspace solid-phase microextraction (HS-SPME) combined with gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS) to examine the differences in the peanut oil aroma on the basis of variety, roasting temperatures, and pressing components. The results revealed that the optimal conditions for extracting peanut oil were achieved through the use of 50/30 µm DVB/CAR/PDMS fibers at 60 °C for 50 min. The primary compounds present in peanut oil were pyrazines. When peanuts were roasted, the temperature raised from 120 °C to 140 °C and the content of aldehydes in peanut oil increased; however, the content of aldehydes in No. 9 oil at 160 °C decreased. The components of peanut shell oil varied depending on the peanut variety. The most marked difference was observed in terms of the main compound at the two roasting temperatures. This compound was a pyrazine, and the content increased with the roasting temperature in hekei oils. When the roasting temperature was lower, No. 9 oil contained more fatty acid oxidation products such as hexanal, heptanal, and nonanal. When the roasting temperature increased, No. 9 oil contained more furfural and 5-methylfurfural. Heren oil was easier to oxidize and produced nonanal that possessed a fatty aroma.

Peanut selenium distribution, concentration, speciation, and effects on proteins after exogenous selenium biofortification.

Fortification of Se is vital importance for both nutritional demand and prevention of Se-deficiency-related diseases. To better understand t selenium distribution, concentration, speciation, its effects on proteins, and cytotoxic activity, the biofortification of exogenous Se in peanut was conducted in this study. Our data have shown that foliar spraying of Se-riched fertilizer was more efficient for biotransformation of inorganic Se to organic Se by peanut plant. Besides, the Se content in peanut was increased in a dose-dependent manner. Our present study also confirmed that SeCys2, MeSeCys, and SeMet were the main Se speciation within peanut proteins. Moreover, the secondary structure and thermostability of peanut protein were altered as a result of the Se treatments, and these alterations could be attributed to the replacements of cysteine and methionine by selenocysteine and selenomethionine, respectively. The Se-enriched peanut protein could significantly inhibit the growth of Caco-2 and HepG2 in a concentration-dependent manner.

Composition and Rheological Properties of Peanut Oil Bodies from Aqueous Enzymatic Extraction.

In this study, the relationship between the composition and rheological properties of peanut oil bodies from aqueous enzymatic extraction was evaluated. Aqueous enzymatic extraction using a combination of cellulase and pectinase at a 1:1 ratio effectively destroyed the structure of the cell wall and resulted in the maximum oil body yield of 90.7%. The microstructure and interfacial membrane composition of the peanut oil bodies were observed by confocal laser scanning microscopy. The oil bodies contained three inherent proteins (oleosin, caleosin, and steroleosin) along with two adsorbed foreign proteins (arachin and lipoxygenase). Five phospholipids were detected using 31P nuclear magnetic resonance spectroscopy. Among them, phosphatidylcholine, which plays a major role in the stability of oil bodies, was the most abundant. The measured rheological properties indicated that the oil bodies were a typical elastic system. Elevated temperature and high-speed shear destroyed the binding between proteins and phospholipids, reducing the oil body stability. The findings will facilitate the commercial application of peanut oil bodies by improving the extraction rate of peanut oil bodies and clarifying their stabilization mechanism.Practical Application: This paper studies the enzymatic extraction, composition and rheological properties of peanut oil bodies. It provides a theoretical basis for the large-scale application of peanut oil bodies in the food and cosmetic industries. It is beneficial to improve the application value of peanut resources.

Application of natural cotton fibers as an extraction sorbent for the detection of trans-resveratrol in adulterated peanut oils.

The current study develops an effective, convenient, low-cost, and environmentally friendly method for determining trans-resveratrol (TRA) in peanut oils, the unique proportion of peanut oil, by employing natural cotton fibers without any pretreatment as extraction sorbent and an in-syringe extraction device. The primary factors affecting the extraction recovery are optimized in detail. The condition of 200.0 mg of cotton fibers, six push-pull times, 2.0 mL of n-hexane as washing solvent and 2.0 mL of ethanol as desorption solvent is selected as the best. The linear range is demonstrated to be 10-1000 ng/g with a satisfactory correlation coefficient (R2 = 0.9995), while the limit of detection is calculated as 2.47 ng/g. In addition, the recoveries of TRA are obtained in the range of 93.8-104.4% with RSDs less than 5.5%. Finally, the developed method is successfully applied to determine TRA concentrations in commercial peanut oils and other edible oils.

Action of phytosterols on thermally induced trans fatty acids in peanut oil.

The effects of six phytosterols on thermally induced trans fatty acids (TFAs) in peanut oil were investigated. Peanut oil, triolein, trilinolein and trilinolenin heated at 180 °C for 12 and 24 h with or without phytosterols were analyzed by GC-FID. The atomic net charge distribution, frontier molecular orbital energy (FMOE), and bond dissociation energy (BDE) of six phytosterols were calculated by density functional theory. Results showed that six phytosterols inhibited the formation of trans oleic acid, trans linoleic acids, trans linolenic acids, and total TFAs. The anti-isomerization effects of phytosterols were mainly associated with hydroxyl site activities, which were affected by the double bond position in the main skeleton of cyclopentane tetrahydrophenanthrene and the number of double bonds on the C17 branch chain. The FMOE difference and BDE of phytosterol molecules were closely related to their anti-isomerization rates. The anti-isomerization mechanisms of phytosterols on TFAs in peanut oil were proposed.

Effect of extrusion temperature on the protein aggregation of wheat gluten with the addition of peanut oil during extrusion.

The influence of extrusion temperature on protein components and aggregation of wheat gluten (WG) and wheat gluten-peanut oil complexes (WPE) during extrusion with the addition of peanut oil was studied. Gliadin content and wheat gluten extractability decreased and glutenin content increased as extrusion temperature increased. At the same extrusion temperature, the gliadin content in WPE was higher than that in WG. The addition of peanut oil also resulted in the higher gluten extractability of WPE than WG. Increasing extrusion temperature also increased the average molecular weight of glutenin and gliadin. The decreased free sulfhydryl (SH) and increased disulfide bonds (SS) indicated that wheat gluten aggregation was promoted, via disulfide cross-linking, when extrusion temperature increased. Furthermore, increased temperature promoted the aggregation of gluten by increasing sulfhydryl-disulfide bond (SH-SS) interchange during extrusion. When the secondary structure of wheat gluten was analyzed by circular dichroism, the relative gluten α-helix content was decreased and the relative ß-sheet content was increased. Also, the results of scanning electron microscopy (SEM) showed the size of the resultant particles increased with temperature, and the mean particle size of WPE was higher than WG. This research shows that extrusion temperature promotes gluten aggregation of WG and WPE. It provides basic data to support the study of gluten-lipid extrusion in the field of protein processing.

Effects of plant oils with different fatty acid composition on cardiovascular risk factors in moderately hypercholesteremic Chinese adults: a randomized, double-blinded, parallel-designed trial.

OBJECTIVES: Plant oil for cooking typically provides 40% to 50% of dietary fat, 65% of linoleic acid, 44% of α-linolenic acid and 41% of oleic acid in the Chinese diet. However, the comparative effects of fatty acids derived from plant oil on cardiovascular risk factors in Chinese are still inconclusive. Hence, the aim of this study is to investigate whether cardiovascular risk factors are altered depending on various types of plant oils such as peanut oil rich in oleic acid, corn oil rich in linoleic acid, and blend oil fortified by α-linolenic acid. DESIGN: A randomized, double-blinded, parallel-designed trial. SETTING: The First and the Second Affiliated Hospital of Sun Yat-sen University, Guangzhou, China. PARTICIPANTS: A total of 251 volunteers with fasting blood total cholesterol between 5.13 and 8.00 mmol L-1 were enrolled. INTERVENTION: Volunteers received peanut oil, corn oil or blend oil to use for cooking for one year. MAIN OUTCOME MEASURES: The erythrocyte membrane fatty acid composition, fasting plasma lipids, glucose and insulin concentrations and high sensitivity C-reactive protein (hsCRP) levels were measured before, during and after the intervention. The level of α-linolenic acid in erythrocyte membranes was significantly increased in the blend oil group after the intervention (P < 0.001). The level of other fatty acids did not show any statistically significant differences between the three groups. No significant differences were observed in the concentrations of fasting plasma lipids, hsCRP, glucose, and insulin among the three groups using different types of plant oils. CONCLUSIONS: The results suggest that although ingesting cooking oil with different fatty acid composition for one year could change erythrocyte membrane fatty acid compositions, it did not significantly modify cardiovascular risk factors in moderately hypercholesteremic people.

Fate of phospholipids during aqueous extraction processing of peanut and effect of demulsification treatments on oil-phosphorus-content.

PC (phosphatidylcholine), PE (phosphatidylethanolamine), PI (phosphatidylinositol), and PA (phosphatidic acid) in 9 peanut matrices obtained during the AEP (aqueous extraction processing) of peanut were quantified employing HPLC-ELSD analysis in this study. Phosphorus contents of crude oils obtained from different demulsification treatments were also investigated. Decantation had a larger effect than grinding in terms of phospholipids loss due to alkaline-hydrolysis, indicating this processing step was vital for the manipulation of phospholipids levels remained in oil. Over 80% of initial phospholipids were lost during AEP and only 19.8% of initial phospholipids ended up in cream, skim and sediment phase. 52.55% of the remained phospholipids trapped in cream phase. Just 22.16-32.61 mg/kg phosphorus content could be detected in crude oils, which indicated the separation of phospholipids from the cream phase into aqueous medium. Degumming was not essential in AEP of peanut and the waste generated after demulsification could be a source of phospholipids.

Effect of Papain on the Demulsification of Peanut Oil Body Emulsion and the Corresponding Mechanism.

This study investigated the effect of papain on the demulsification of peanut oil body emulsion extracted using an aqueous enzymatic method and the associated mechanism. The highest free oil yield using papain (92.39%) was obtained under the following conditions: an enzymatic hydrolysis temperature of 55°C, sample-to-water ratio of 1:3, enzyme concentration of 1400 U/g, and an enzymatic hydrolysis time of 3 h. Papain degraded the peanut oil body protein to small-molecular-weight peptides (≤ 14.4 kDa). Compared to the emulsion before enzymatic hydrolysis, the amino acid content in the aqueous phase was higher after enzymatic hydrolysis, the viscosity of the oil body emulsion was lower, and the particle diameter of the emulsion was significantly larger. The following demulsification mechanism was derived. Papain degrades the protein on the peanut oil body and dissolves it in water. The outer side of the oil body loses the protection of electrostatic repulsion and steric hindrance provided by the membrane protein. This causes the viscosity of the emulsion system and the molecular steric hindrance to decrease. As a result, the oil droplets gather and eventually demulsify. The results of this study provide the theoretical basis for the instability in oil body emulsions and are expected to promote the application of enzymatic demulsification in industry.