Mechanism, indexes, methods, challenges, and perspectives of edible oil oxidation analysis

Peanut oils from roasting operations: An overview of production technologies, flavor compounds, formation mechanisms, and affecting factors

Fragrant peanut oils (FPOs) are commonly defined as edible peanut oils having strong natural roasted peanut flavor without peculiar unpleasant odors and produced from peanut kernels through roasting/steaming and pressing operations, etc. The flavor of FPOs plays a crucial role in their acceptability and applications and their flavor profiles are an important factor in determining their overall quality. This paper presents a systematic literature review of recent advances and knowledge on FPOs, especially their flavors, in which it is focused on the evaluation of volatile compounds, the factors influencing the formation of flavor compounds, and formation mechanisms of those typical flavor compounds. More than 300 volatiles are found in FPOs, while some key aroma-active compounds and their potential formation pathways are examined. Factors that have big influences on flavor are discussed also, including the properties of raw materials, processing technologies, and storage conditions. Ultimately, the paper highlights the challenges facing, including the challenges in flavor analysis, the relationship between volatile compounds and sensory attributes, as well as the opening of the blackboxes of flavor formations during the processing steps, etc.

CsPbBr3 NCs Confined and In Situ Grown in ZIF-8: A Stable, Sensitive, Reliable Fluorescent Sensor for Evaluating the Acid Value of Edible Oils

Rapidly and sensitively evaluating the acid value (AV) of edible oils is significant to ensuring food quality and safety. Cesium lead bromide perovskite nanocrystals (CsPbBr3 NCs) are an effective candidate for AV detection; however, their instability restricts wide applications. Herein, CsPbBr3@ZIF-8 was prepared by confining and growing CsPbBr3 NCs in situ into zeolitic imidazolate framework-8 (ZIF-8) to improve the stability, and a fluorescence sensor was established to evaluate the AV of edible oils. The results present that CsPbBr3 NCs (below 5 nm) with excellent optical properties were confined and grown in situ in micropores and mesopores of ZIF-8. Meanwhile, CsPbBr3@ZIF-8 had better long-term storage, ultraviolet-irradiation, and water-exposure stabilities, compared with CsPbBr3 NCs. Given the fact that free fatty acids (the major contributor of AV) decrease the fluorescence of CsPbBr3 NCs, the fluorescence intensities of CsPbBr3@ZIF-8 were negative-linearly related to oil AV (R2 = 0.9902) in 0.04-6.00 mg of KOH/g with a 0.06 mg of KOH/g limit of detection. Besides, the practical AV recovery was 92-101% with an average relative standard deviation of 2%. Furthermore, the detection time was 20 min. The response mechanism revealed that free fatty acids could remove surface ligands and increase surface defects to prompt the aggregation of CsPbBr3 NCs and the formation of lattice fringe dislocations, inducing a decrease in the fluorescence. Thus, a stable, sensitive, reliable sensor was established to evaluate the AV of edible oils.

Effect of Pretreatments on the Chemical, Bioactive and Physicochemical Properties of Cinnamomum camphora Seed Kernel Extracts

Cinnamomum camphora seed kernels (CCSKs) are rich in phytochemicals, especially plant extracts. Phytochemicals play a vital role in therapy due to their strong antioxidant and anti-inflammatory activities. Extracts from CCSK can be obtained through multiple steps, including pretreatment, extraction and purification, and the purpose of pretreatment is to separate the oil from other substances in CCSKs. However, C. camphora seed kernel extracts (CKEs) were usually considered as by-products and discarded, and their potential bioactive values were underestimated. Additionally, little has been known about the effect of pretreatment on CKE. This study aimed to investigate the effects of pretreatment methods (including the solvent extraction method, cold pressing method, aqueous extraction method and sub-critical fluid extraction method) on the extraction yields, phytochemical profiles, volatile compounds and antioxidant capacities of different CKE samples. The results showed that the CKE samples were rich in phenolic compounds (15.28-20.29%) and alkaloids (24.44-27.41%). The extraction yield, bioactive substances content and in vitro antioxidant capacity of CKE pretreated by the sub-critical fluid extraction method (CKE-SCFE) were better than CKEs obtained by other methods. CKE pretreated by the solvent extraction method (CKE-SE) showed the best lipid emulsion protective capacity. Moreover, the volatile substances composition of the CKE samples was greatly influenced by the pretreatment method. The results provided a fundamental basis for evaluating the quality and nutritional value of CKE and increasing the economic value of by-products derived from CCSK.

Pickering emulsion gel of polyunsaturated fatty acid-rich oils stabilized by zein-tannic acid green nanoparticles for storage and oxidation stability enhancement

HYPOTHESIS

Poor storage stability and oxidative deterioration are the common drawbacks of edible oils rich in polyunsaturated fatty acids (PUFAs). We hypothesized that the natural zein/tannic acid self-assembly nanoparticles (ZT NPs) could be employed as stabilizers to anchor at the oil-water interface, thus constructing Pickering emulsion gel (PKEG) system for three types of PUFA-rich oils, soybean oil (SO), fish oil (FO) and cod liver oil (CLO), to improve the storage and oxidation stability.

EXPERIMENTS

ZT NPs were prepared by the anti-solvent coprecipitation method, and the three-phase contact angle, FT-IR, and XRD were mainly characterized. To observe the shell-core structure and oil-water interface details of SO/FO/CLO PKEGs by confocal laser scanning microscope and cryo-scanning electron microscope. Accelerated oxidation of FO was performed to assess the protective effect of PKEG on lipids.

FINDINGS

The SO, FO, and CLO PKEGs stabilized by 2 % ZT NPs, with oil fraction (φ = 0.5-0.6), were obtained. PKEGs show high viscoelasticity, clear shell-core structure spatial network structure, and ideal storage stability. Under accelerated oxidation, the degree of oxidative rancidity of FO PKEG was obviously lower than that of free FO. Overall, this work opens up new possibilities for using natural PKEG to prevent oxidative deterioration and prolong the shelf-life of PUFA-rich oils.

Design of an Artificial Intelligence of Things-Based Sesame Oil Evaluator for Quality Assessment Using Gas Sensors and Deep Learning Mechanisms

Traditional oil quality measurement is mostly based on chemical indicators such as acid value, peroxide value, and p-anisidine value. This process requires specialized knowledge and involves complex steps. Hence, this study designs and proposes a Sesame Oil Quality Assessment Service Platform, which is composed of an Intelligent Sesame Oil Evaluator (ISO Evaluator) and a Cloud Service Platform. Users can quickly assess the quality of sesame oil using this platform. The ISO Evaluator employs Artificial Intelligence of Things (AIoT) sensors to detect changes in volatile gases and the color of the oil during storage. It utilizes deep learning mechanisms, including Artificial Neural Network (ANN), Convolutional Neural Network (CNN), and Long Short-Term Memory (LSTM) to determine and evaluate the quality of the sesame oil. Evaluation results demonstrate that the linear discriminant analysis (LDA) value is 95.13. The MQ2, MQ3, MQ4, MQ7, and MQ8 sensors have a positive correlation. The CNN combined with an ANN model achieves a Mean Absolute Percentage Error (MAPE) of 8.1820% for predicting oil quality, while the LSTM model predicts future variations in oil quality indicators with a MAPE of 0.44%. Finally, the designed Sesame Oil Quality Assessment Service Platform effectively addresses issues related to digitization, quality measurement, supply quality observation, and scalability.

Maternal diet associated with infants' intestinal microbiota mediated by predominant long-chain fatty acid in breast milk

Introduction

Long-chain fatty acids in breast milk are affected by the mother's diet and play an important role in the growth, development, and immune construction of infants. This study aims to explore the correlation between maternal diet, breast milk fatty acids (FAs), and the infant intestinal flora.

Methods

We enrolled 56 paired mothers and their infants; both breast milk samples and infants' fecal samples were collected to determine the long-chain FA content of breast milk by ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS), and metagenomic technology was applied to determine the microbial composition of infant feces. The maternal diet was also investigated using a 24-h dietary recall.

Results

The results indicated that the fat contribution rates of edible oils in the maternal diet are significantly positively correlated with the contents of certain long-chain fatty acids (C16:0, C18:1, C16:1, and C22:4) in breast milk, which mainly regulate the abundance of Lacticaseibacillus rhamnosus, Lacticaseibacillus fermentum, and Lacticaseibacillus paracasei in the infant gut. Through KEGG pathway analysis, our data revealed that the long-chain FAs in different groups of breast milk were significantly correlated with the pathways of biotin metabolism, glycerolipid metabolism, and starch and sucrose metabolism.

Discussion

The results of this study suggest a pathway in which the diets of lactating mothers may affect the composition of the infant intestinal microbiota by influencing breast milk FAs and then further regulating infant health.

Characterization of Traditional Chinese Sesame Oil by Using Headspace Solid-Phase Microextraction/Gas Chromatography-Mass Spectrometry, Electronic Nose, Sensory Evaluation, and RapidOxy

Xiao Mo Xiang You (XMXY) is a traditional Chinese sesame oil variety that is obtained through a hot water flotation process. This unique process gives the oil a unique aroma, health benefits, and excellent product stability. Although XMXY is always the most expensive among all the sesame oil varieties, it is usually used as a flavoring in many traditional Chinese daily food products and is increasingly popular. In order to reveal the characteristics of the oil, the volatile components, sensory evaluation, and oxidation stability of five XMXY samples were, respectively, analyzed by using headspace solid-phase microextraction/gas chromatography−mass spectrometry, an electronic nose, sensory evaluation, and RapidOxy. Comparisons and multidimensional statistical analysis were also carried out to distinguish XMXY from roasted sesame oil (RSO) and cold-pressed sesame oil (CSO) samples. In total, 69 volatiles were identified from XMXY, RSO, and CSO samples. Some compounds possessed high odor activity value (OAV > 1) in XMXY, including heterocyclic compounds, phenols, and sulfur-containing compounds. Additionally, they were also the main volatile components that distinguish XMXY from RSO and CSO. Roasted and nutty aromas were the dominant aroma attributes of XMXY. XMXY had better flavor intensity and oxidation stability than the other two sesame oil samples. These results are very valuable for the quality control and product identification of traditional Chinese sesame oil.

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.

An Evaluation Model for the Quality of Frying Oil Using Key Aldehyde Detected by HS-GC/MS

To establish a practical model for evaluating the oxidation of frying oil using aldehydes, the aldehydes of 10 commercial oils during frying at 180 °C were identified using headspace-gas chromatography/mass spectrometry, and the changes of common aldehydes and their correlation with carbonyl values (CV) were analyzed. The results showed that the total peak area of aldehydes increased significantly with heating time, which was related to the fatty acid and tocopherol contents of the oils. There were four common aldehydes with different trends during frying, namely, pentanal, hexanal, (E)-hept-2-enal, and nonanal. Moreover, pentanal with a high correlation with CV was selected as the quality evaluating index of frying oil due to its stable accumulation over time. Based on the linear fitting relationships between CV and pentanal, as well as the initial content ratio of linoleic acid to palmitic acid and total tocopherols in oils, a predictive model was established for evaluating the quality of frying oils with high precision and non-reagent by using mass spectrometry. In summary, this work provides theoretical support for using aldehyde as the quality evaluation index of frying oil and provides a new idea for evaluating oil deterioration from the perspective of volatile compounds.