Journal of the American Oil Chemists Society最新文献

Effective removal of the fatty acid matrix and enrichment of trace target components is a key step in the quantitative analysis of minor components in edible oils. In this study, a novel sample pretreatment method named freezing crystallization was developed to analyze pigments in extra virgin olive oil (EVOO). The limits of detection and limits of quantification of this method were 0.125–0.625 μg/mL and 0.5–2.5 μg/mL, respectively. Linear correlations were obtained (r² ≥ 0.9995), and the recoveries at three spiked levels were 84.2%–105.8%. Besides, the primary pigment components information combined with machine learning to classify the origin of Chinese EVOOs. The k-nearest neighbor (kNN), decision tree (DT), and random forest (RF) were employed to classify the origin of EVOOs, and the accuracies were up to 88%, 88%, and 96%, respectively. This result shows that the novel method has good accuracy and stability, and pigments can be used as a basis for classifying the geographical origin of Chinese domestic EVOOs.

Whey, the largest co-product source of the dairy industry, contains highly valued components such as phospholipids. For this work, cheddar cheese whey's phospholipids were precipitated using thermocalcic aggregation. The impact of calcium acetate concentration, pH, and temperature as processing conditions was evaluated. The results showed that the highest recovery of phospholipids was achieved at pH 6.5, a calcium acetate concentration of 50 mM, and at a temperature of 60 °C. Calcium acetate concentration and pH were statistically significant factors (p < 0.05), but temperature was not. For all treatments, the majority (95%–98%) of the protein remained in the supernatant. Under the identified best conditions, up to 92% of the phospholipids of the milk fat globule membrane were precipitated in the pellet, while 96% of the proteins remained in the supernatant. The salt recovery, that is, in the precipitate, was 53%, but decreasing the amount of salt used would result in incomplete recovery of the phospholipids. Gel electrophoresis showed that the majority of the globule membrane proteins were precipitated into the pellet, while the supernatant only contained major whey proteins. This procedure demonstrates a simple and cost-effective method to utilize cheese whey for phospholipids precipitation that can be further processed into a value-added food or nutraceutical ingredient. This technique, after more fully optimized, would allow for easy implementation in small cheese production facilities.

The synthesis of docosahexaenoic acid (DHA)-enriched medium- and long-chain triacylglycerols (MLCT), particularly with DHA at the sn-2 position and medium chain fatty acids (MCFA) at the sn-1,3 positions, is a promising strategy to enhance DHA bioavailability. However, the synthesis of DHA-enriched MLCTs is hindered by steric hindrance due to DHA's very long-chain polyunsaturated fatty acids. This study investigates the enzymatic interesterification of microalgae oil and medium chain triacylglycerols (MCT) using regio-selective lipases with different typo-selectivities. We evaluated the impact of interesterification conditions (substrate ratio, type of lipase, lipase loading, temperature and time) on MLCT yield, DHA distribution at sn-2 and acyl migration. The optimal conditions, using 6% Rhizopus oryzae lipase at 50 °C for 8 h achieved a MLCT yield of 64.9% ± 0.4%, with 37.5% DHA at the sn-2 position. In comparison, Rhizomucor miehei lipase produced a lower yield (49.5% ± 1.0%) but a higher DHA distribution at sn-2 position (46.3% ± 0.2%). Given DHA's susceptibility to oxidation, we also integrated ultrasound (US) pre-treatment with enzymatic interesterification to improve MLCT yield. Using 4% RO with US pre-treatment (40% amplitude, 4 s on/6 s off duty cycle, 8 min) increased MLCT yield from 36.1% ± 0.4% to 42.0% ± 0.7% (p < 0.05), with a lower reaction temperature (30 °C) and shorter duration (4 h), without compromising oil quality and lipase activity. These findings emphasize the importance of lipase selection, acyl migration, and US pre-treatment for enhancing oxidative sensitive DHA-enriched MLCT production, offering applications in nutritional and functional food formulations.

Although aqueous and enzymatic extractions are solvent-free alternatives for extracting oil and proteins from almond flour, most of the extracted oil becomes entrapped in an emulsion and needs demulsification for recovery. To assess how extraction and demulsification methods impact yields and quality, a lipidomic approach was used to investigate the effects of aqueous and enzymatic extractions processes and recovery strategies, including pH-shift and protease addition, on almond oil quality. Liquid chromatography-mass spectrometry, conventional oxidation markers (peroxide value, p-anisidine), fatty acid profile, lipid class, total phenolic content and antioxidant activity were employed to determine the combined impact of extraction and recovery methods on lipid quality and composition. Peroxide value (1.8–2.0 mEq/kg oil), p-anisidine (0.1–0.4), and fatty acid composition of the oils (18:1 72%–75%, 18:2 22%–25%, 16:0 4%–5%) showed no significant changes based on extraction and recovery methods. However, oxylipin analysis demonstrated that the solvent-extracted oil had higher levels of 13-hydroxyoctadecadienoic acid (13-HODE) and 12(13)-epoxyoctadecenoic acid (12(13)-EpOME) compared to aqueous and enzymatically extracted oils, regardless of the demulsification method. Additionally, the solvent-extracted oil exhibited lower phenolic content and antioxidant capacity. This work provides valuable insights into how environmentally friendly extraction and recovery methods impact almond oil quality, contributing to processing optimization.

This study explores biodiesel production from palm fatty acid distillate (PFAD), focusing on optimizing the esterification process through the use of co-solvents and molecular sieves under high-temperature and high-pressure conditions. Palm fatty acid distillate, a low-value by-product of crude palm oil refining, was used as a feedstock with a free fatty acid (FFA) content of 88.4%. Esterification was conducted in a 400-L batch reactor at 130 °C and 15 bar, using methanol at a molar ratio of 1:3.7 and 1.834 wt% sulfuric acid as a catalyst. Co-solvents such as dichlorobenzene enhanced miscibility, while molecular sieves effectively removed water to increase reaction efficiency. The optimized process achieved a fatty acid methyl ester (FAME) yield of 97.44% within 30 min, meeting European Standard EN 14214:2003. The study highlights the potential of PFAD as an economical and sustainable biodiesel feedstock, with production costs of 0.45 USD per liter. This research contributes to the development of high-efficiency biodiesel production processes that reduce reliance on fossil fuels and support renewable energy initiatives.

Silkworm pupae oil (SPO) with high amount of unsaturation due to rich in oleic acid and α-linolenic acids has been chosen for this investigation. Epoxidized silkworm pupae oil (ESPO) was produced by in situ generated peroxycitric with citric acid (CA) and hydrogen peroxide (H₂O₂). Literature covering the topic of epoxidation, including the catalytic aspect, is vast. No review articles have been written on the synthesis of epoxides from SPO without the catalyst to the best of our knowledge. Here, CA itself behaves as an oxygen carrier without any catalyst and H₂O₂ as an oxygen donor, which favors the epoxidation reaction. The epoxidation process was optimized by factors like temperature, time, and CA ratio. Fourier transform infrared (FTIR) analysis confirmed the presence of epoxy groups and the absence of (CC) bonds in ESPO. Optimal conditions for epoxidation were 70 °C, 0.75 mol/L CA, and 7 h, resulting in 92.1% double bond conversion (DBC) and 84.7% relative oxirane conversion (RC). The polymerized ESPO coated on mild steel (MS) exhibited enhanced corrosion resistance, with inhibition efficiency rising from 83.86% to 99.42% due to effective pore prevention and ion modification during curing.

Structured lipids (SLs) containing docosahexaenoic acid (DHA), eicosapentaenoic acid (EPA), and DHA + EPA were synthesized via enzymatic acidolysis using virgin coconut oil (VCO) as the substrate in n-hexane. Commercially available enzymes Lipozyme TL IM (produced from Thermomyces lanuginosus, a 1,3-specific lipase), Lipozyme IM60 (produced from Rhizomucor miehei, a 1,3-specific lipase), and non-specific lipase from Candida rugosa (powder) were used as biocatalysts. The T. lanuginosus lipase was chosen to evaluate the effects of various parameters on the incorporation of PUFAs into VCO and to optimize the process. As the enzyme load increased from 1% to 4%, the incorporation of omega-3 PUFAs also increased; however, it decreased when the enzyme load was further increased to 6%. The incorporation of these fatty acids increased with reaction time from 12 to 36 h but decreased at 48 h. Similarly, the incorporation increased with temperature from 35 to 45 °C, but decreased at 55 and 65 °C. The highest incorporation rates of DHA (18.91%), EPA (30.38%), and DHA + EPA (34.64%) were achieved at a mole ratio of 1:3 (VCO to DHA or EPA) or 1:3:3 (VCO to DHA + EPA), with a 4% enzyme load, 36 h incubation time, and a temperature of 45 °C. A central composite design (CCD) with three levels and three factors—reaction temperature (35, 45, and 55 °C), enzyme amount (2%, 4%, and 6%), and reaction time (24, 36, and 48 h)—was used to model and optimize the reaction conditions via response surface methodology (RSM). Under optimal conditions of 3.3% T. lanuginosus enzyme, 42.22 °C, and 33.38 h, the incorporation rates were 32.92% for DHA, 44.48% for EPA, and 47.04% for DHA + EPA in VCO.

The soap content in biodiesel is an important challenge during the production and purification processing of biodiesel. Natural deep eutectic solvents (NADES) have recently attracted considerable interest as an environmentally suitable substitute for traditional solvents in the biodiesel industry. This work investigates the soap removal from the contaminated biodiesel using NADES. Eight choline chloride-based deep eutectic solvents (DESs) were screened using the conductor-like screening model for real solvents (COSMO-RS) to identify the most suitable solvent for soap removal and were validated experimentally. The effect of NADES molar ratio, NADES:biodiesel ratio, mixing speed and extraction time on the extraction efficiency were investigated. COSMO-RS screening revealed that the malonic acid-based NADES possess higher soap elimination, and this is compatible with the experimental screening. The higher extraction efficiency of 99.18% was achieved under the optimum conditions of 1:3 of NADES molar ratio, 1:1 DES:biodiesel, 150 rpm and 15 min of extraction time. The soap removal followed the first-order kinetic equation with a rate constant of 0.183 min⁻¹. This technique offers innovative and environmentally friendly routes for downstream processing of contaminated biodiesel.

Phospholipase C (PLC) enzymes play a pivotal role in the degumming process of edible oils, which is essential for producing high-quality refined oils. The enzymatic degumming process, compared with conventional chemical methods, offers significant advantages including improved oil yield, reduced environmental impact, and lower operational costs. However, the industrial application of PLC enzymes is often hindered by their limited stability under harsh processing conditions. This has driven extensive research efforts toward engineering thermostable PLC variants that can withstand the high temperatures and harsh environments typical of oil refining processes. In this review, we explore the latest advancements in the application, design and optimization of thermostable PLC enzymes. We discuss the fundamental economic and ecological interest behind the goal of obtaining thermostable enzymes, and two approaches to the problem, namely the search for enzymes in thermophilic organisms and the design of new sequences with improved stability and activity parameters.

Thermal decomposition of hydroperoxides during frying generates several secondary oxidation products, with carbonyl compounds predominating. p-Anisidine value (p-AV) is the most prominent official method for quantifying these carbonyl compounds, utilizing the reaction between carbonyls, principally 2-alkenals and 2,4-dienals, and p-anisidine (para-methoxy aniline) reagent. It is well known, however, that despite the success of the p-AV test, the data is generally skewed toward the unsaturated carbonyl compounds and the reagent is highly toxic and presumably, carcinogenic, limiting its acceptability in some food processing settings. A method proposed in the current study utilizes the reaction between carbonyl compounds, specifically aldehydes, and purpald reagent (4-Amino-3-hydrazino-5-mercapto-1,2,4-triazole). Unlike the p-AV, the purpald test is very specific to aldehydes with negligible interference from other functional groups (e.g., ketones, carboxylic acids, esters). Interestingly, the reaction between aldehydes and purpald reagent is skewed toward saturated aldehydes by nearly the same factor that the p-AV is skewed toward unsaturated aldehydes, providing a complimentary information to the p-AV on the nature of secondary aldehydes formed during thermo-oxidative degradation of lipid hydroperoxides. Further, a second method utilizing p-anisidine hydrochloride reagent was optimized for the determination of carbonyl secondary oxidation compounds. A strong correlation was found between each of the proposed alternatives and the p-AV method, providing the opportunity for indirect determination for p-AV in food processing settings where the p-anisidine reagent is considered unacceptable regarding environmental health and safety. Challenges and limitations of the proposed chemical alternative methods are also presented.