Effects of hot and cold-pressed processes on volatile compounds of peanut oil and corresponding analysis of characteristic flavor components

Lipidomics and metabolomics reveal the molecular mechanisms underlying the effect of thermal treatment on composition and oxidative stability of walnut oil

Roasting walnut kernel significantly improves the oxidative stability and sensory properties of its oil. However, the effect of roasting temperatures on the molecular change of main components and micronutrients in walnut oil is still unclear. Herein, lipidomics and metabolomics were integrated to comprehensively profile the walnut oil obtained at different roasting temperatures (30 °C, 120 °C, 140 °C, 160 °C, and 180 °C). Lipidomics showed that the content of glycerolipids, sphingolipids, and glycerophospholipids decreased with roasting temperatures, while the oxidized fatty acids and triglycerides increased. Ratios of linoleic acid and linolenic acid varied with roasting temperatures and were most close to 4-6:1 at 140 °C, 160 °C, and 180 °C. Major classes of micronutrients showed a tendency to increase at the roasting temperature of 120 °C and 140 °C, then decrease at 160 °C and 180 °C. Liposoluble amino acids identified for the first time in walnut oil varied with roasting temperatures. Correlation analysis demonstrated that the higher contents of liposoluble amino acids and phenolics are positively associated with enhanced oxidative stability of walnut oil obtained at 140 °C. Furthermore, glutamine and 5-oxo-D-proline were expected to be potential biomarkers to differentiate the fresh and roasted walnut oil. The study is expected to provide new insight into the change mechanism of both major lipids and micronutrients in walnut oil during the roasting process.

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.

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.

Comparison of chemical compositions and aroma characteristics of walnut oil prepared by different roasting processes

Walnut oil is an edible oil with high nutritional value, and the roasting process influences its quality and flavor. This study aimed to investigate the effects of roasting on the fatty acid composition, bioactive compounds (tocopherols, polyphenols, and phytosterols), and antioxidant capacity of walnut oil. Additionally, the aroma compounds and sensory characteristics were evaluated to comprehensively assess the variations in walnut oil after roasting. Roasting resulted in no notable impact on the fatty acid composition of walnut oil but increased the content of tocopherols and polyphenols in walnut oil, increasing its antioxidant capacity. Heavy roasting (160°C/20 min) reduced the phytosterol content in walnut oil by 2.3%. In total, 146 volatile compounds were detected in both cold-pressed and roasted walnut oil using headspace solid-phase microextraction-gas chromatography-mass spectrometry, and 32 key aroma compounds were identified. Aromatic aldehydes, aliphatic aldehydes, and heterocyclic compounds significantly contributed to fragrant walnut oil. Furthermore, the principal component analysis based on quality characteristics and sensory evaluation indicated that moderate roasting (130°C/20 min, 130°C/30 min, and 160°C/10 min) provided walnut oil with a sweet, nutty, and roasted aroma, as well as high levels of linoleic acid, phytosterols, and γ-tocopherol. Although heavy roasting (160°C/15 min and 160°C/20 min) enhanced the antioxidant capacities of walnut oils due to high levels of polyphenols, the oils exhibited an unpleasant burnt aroma. This study showed that roasting promoted the quality and flavor of walnut oil, and moderate conditions endowed walnut oil with a characteristic-rich flavor while maintaining excellent quality.

The effect of extraction methods on the components and quality of Camellia oleifera oil: Focusing on the flavor and lipidomics

The objective of this study was to systematically elucidate the effects of conventional (Cold Pressing, CP; Hot Pressing, HP; Soxhlet Extraction; SE) and novel methods (Microwave-Assisted Extraction, MAE) on the physicochemical properties, bio-active substances, flavor and lipidomics of Camellia oleifera oil (COO). The cold-pressed COO contained the highest contents of squalene (176.38 mg/kg), α-tocopherol (330.52 mg/kg), polyphenols (68.33 mg/kg) and phytosterols (2782.55 mg/kg). Oleic acid was observed as the predominant fatty acid with the content of approximately 80%. HS-GC-IMS identified 47 volatile compounds, including 11 aldehydes, 11 ketones, 11 alcohols, 2 acids, 8 esters, 2 pyrazines, 1 furan, and 1 thiophene. A total of 5 lipid classes and 30 lipid subclasses of 339 lipids were identifed, among which TGs and DGs were observed as the major lipids. In summary, both cold-pressed and microwave-assisted technologies provided high-quality COO with high content of bio-active substances and diglycerides/triglycerides.

Anti-mildew and fresh-keeping effect of Lactiplantibacillus paraplantarum P3 cell-free supernatant on fresh in-shell peanuts during storage process

Lactiplantibacillus paraplantarum P3 (L. paraplantarum P3) cell-free supernatant (CFS) with good antifungal effect was sprayed on fresh in-shell peanuts stored at 5 °C and 30 °C to explore its effect on the microorganisms and quality of fresh in-shell peanuts during storage process. Results showed that L. paraplantarum P3 CFS effectively maintained good quality of fresh in-shell peanuts by not only reducing fungi amount and the mildew rate, but also improving the morphology, color and flavor. Besides, L. paraplantarum P3 CFS activated plant mitogen-activated protein kinase signaling pathway and plant hormone signaling pathway to produce more ethylene, gibberellin regulatory proteins and other substances to enhance plant resistance to pathogenic microorganisms. L. paraplantarum P3 CFS could also induce the biosynthesis of glycerophospholipid and arginine to increase the stress resistance of fresh peanuts. This study provides research data for the application of L. paraplantarum P3 CFS in the preservation and antimildew of fresh in-shell peanuts.

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.

Effect of Roasting on the Chemical Composition and Oxidative Stability of Tomato (Solanum lycopersicum L.) Seed Oil

In this study, tomato seed (TS) samples were subjected to different roasting conditions (90-170 °C and 10-30 min) to compare their effects on the chemical composition and oxidative stability of tomato seed oil (TSO). Unroasted TS was considered as a control sample. Our results revealed that moderate roasting (130 °C/20 min) can significantly increase the content of linoleic acid (54.01-54.89%), linolenic acid (2.17-2.41%), phytosterols (2789.56-3037.31 mg/kg), squalene (5.06-13.10 mg/kg), total phenols (22.37-22.67 mg GAE/100 g), and other functional components (p < 0.05) in TSO, while the antioxidant activity (via DPPH, ABTS, and FRAP assays) also increased. In addition, the tocopherol content decreased significantly (758.53-729.50 mg/kg). Accelerated oxidation experiments showed that roasting (170 °C/30 min) increased the oxidative stability index (OSI) of TSO from 5.35 to 7.07 h (p < 0.05). Furthermore, roasting gradually increased the content of 5-hydroxymethylfurfural (HMF) (0-1.74 mg/kg), which indicates that the oxidative stability and the degree of the Maillard reaction increased upon roasting. Principal component analysis (PCA) and hierarchical cluster analysis (HCA) showed that moderate roasting (130 °C/20 min) improved the chemical composition, antioxidant activity, and oxidative stability of TSO. Furthermore, this work provides a useful theoretical basis for the processing and wide application of TSO in the pharmaceutical and food industries.

A review on the biological and bioactive components of Cyperus esculentus L.: insight on food, health and nutrition

Tiger nut (Cyperus esculentus L.) is a small, tuberous root vegetable that has gained increasing attention in recent years due to its potential health benefits. This review article provides an elaborate overview of tiger nut, including its botany, historical uses, nutritional composition, potential health benefits and traditional medicinal uses. This review article comprehensively discusses the nutritional profile of tiger nut, providing a detailed understanding of its nutrient content. Furthermore, the potential health benefits of tiger nut are thoroughly reviewed, including its effects on digestive health, cardiovascular health, blood sugar control, immune function and other potential therapeutic uses. Scientific articles used for this review were retrieved from ScienceDirect, Google Scholar, PubMed and SciELO databases. Only articles published between 1997 and 2022 were used for research. This review contributes to a better understanding of tiger nut and its prospective uses in functional foods and medicine by combining the available scientific material. © 2024 Society of Chemical Industry.

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.

Characterization of aroma-active compounds in sesame hulls at different roasting temperatures by SAFE and GC-O-MS

The study characterized the aroma-active compounds produced by sesame hulls at three roasting temperatures and analyzed the similarities and differences in the aroma profile of sesame hulls with whole seeds and kernels after roasting. Roasting hulls produced mainly furans, aldehydes, and ketones volatiles. 140 Compounds were identified as aroma-active compounds, including 36 key aroma compounds (odor activity value, OAV ≥ 1). Among them, furanone (caramel-like, OAV = 80), 3-methylbutanal (fruity, OAV = 124), and 2-methoxy-4-vinylphenol (burnt, smoky, OAV = 160) gave hulls (180 °C) sweet, burnt, and smoky aroma. Due to the contribution of vanillin (fatty, sweet milk, OAV = 45), 2-hydroxy-3-butanone (caramel-like, roast, OAV = 46), and 2-methoxy-4-vinylphenol (OAV = 78), hulls (200 °C) shown strong sweet and roast note. These results identified compounds that contributed significantly to the aroma of sesame hulls and elucidated the contribution of sesame hulls to the flavor of roasted whole seeds and sesame oil.

Effect of enzymatic Maillard reaction conditions on physicochemical properties, nutrition, fatty acids composition and key aroma compounds of fragrant rapeseed oil

BACKGROUND

A new enzymatic hydrolysis-based process inspired by the Maillard reaction can produce strong flavored, high-value rapeseed oil that meets safety requirements. In the present study, the effect of reaction time (10-30 min) and temperature (130-160 °C) on the physicochemical properties, nutritional status, fatty acids composition and key aroma compounds of fragrant rapeseed oil (FRO) was investigated.

RESULTS

An increasing reaction time and temperature substantially decreased the total tocopherol, polyphenol and sterol contents of FRO, but increased benzo[a]pyrene content, as well as the acid and peroxide values, which did not exceed the European Union legislation limit. Among the volatile components, 2,5-dimethyl was the main substance contributing to the barbecue flavor of FRO. The 150 °C for 30 min reaction conditions produced a FRO with a strong, fragrant flavor, with high total tocopherol (560.15 mg kg-1 ), polyphenol (6.82 mg kg-1 ) and sterol (790.65 mg kg-1 ) contents; acceptable acid (1.60 mg g-1 ) and peroxide values (4.78 mg g-1 ); and low benzo[a]pyrene (1.39 mg g-1 ) content. These were the optimal conditions for the enzymatic Maillard reaction, according to the principal component analysis. Furthermore, hierarchical cluster analysis showed that reaction temperature had a stronger effect on FRO than reaction time.

CONCLUSION

The optimal enzymatic Maillard reaction conditions for the production of FRO are heating at 150 °C for 30 min. These findings provide new foundations for better understanding the composition and flavor profile of FRO, toward guiding its industrial production. © 2023 Society of Chemical Industry.

Analysis of roasted peanuts based on GC-MS combined with GC-IMS

The present study used gas chromatography-mass spectrometry (GC-MS) and gas chromatography-ion mobility spectrometry (GC-IMS) to separate and identify the characteristic volatile flavor substances in 30 roasted peanut samples. GC-MS identified 59 volatile compounds, and GC-IMS detected 61 volatile flavor substances. The 30 peanut varieties were then divided into four groups on the basis of their volatile flavor substances using principal component analysis (PCA), and a fingerprint profile of the varieties' volatile characteristics was established from information peaks identified in the spectra. Descriptive sensory analysis (DSA) was performed to distinguish differences in flavor attributes between roasted peanut varieties. Partial least squares regression (PLSR) was performed with the volatile flavor content of roasted peanuts as the independent variable and the flavor attribute score as the dependent variable. These findings provide a basis for predicting the appeal of roasted peanuts based on their composition and demonstrate a potential avenue for improving food flavor quality.

Peanut oil odor enhances the immunomodulatory effect on immunosuppressed mice by regulating the cAMP signaling pathway via the brain-spleen axis

The role of sniffing relative to immune function has attracted considerable attention. The present study investigated the immunomodulatory effects of peanut oil odor on cyclophosphamide (CTX)-induced immunosuppressed mice. The subset of mice subjected to prolonged (8 h) sniffing peanut oil odor (PL) demonstrated significantly elevated levels of agouti-related peptide, neuropeptide Y, and glutamate (p < 0.05), whereas it significantly down-regulated the level of γ-aminobutyric acid in the brain (p < 0.05). Furthermore, immunohistochemistry results indicated significantly increased expression of mGluR1/5 and decreased expression of GABABR in the hippocampus and hypothalamus (p < 0.05) of the PL group. Additionally, the PL group had significantly up-regulated expression levels of cAMP, Epac, Rap1, ERK1/2 and PKA (p < 0.05) and remarkably increased phosphorylation of CREB in the cAMP signaling pathway (p < 0.05), which influenced the central nervous system. Moreover, compared with CTX-induced mice, the percentages of peripheral blood T lymphocytes (CD3+CD4+ and CD3+CD8+) and the levels of splenic cytokines (IL-2, IL-4, and TNF-α) were significantly increased following PL treatment (p < 0.05). The PL group also showed significantly up-regulated expression levels of cAMP, p-p65, and p-IκBα in the spleen (p < 0.05) by western blot analysis. In summary, PL intervention significantly up-regulated the expression levels of cAMP in the brain (p < 0.05), with subsequent transfer of cAMP to the spleen which promoted phosphorylation of p65 and IκBα. This series of events enhanced the immunity of mice, which confirmed the regulatory effect of PL on the cAMP signaling pathway, thereby enhancing immune function via the brain-spleen axis.

Unraveling the relationship between key aroma components and sensory properties of fragrant peanut oils based on flavoromics and machine learning

Key aroma components of 33 fragrant peanut oils with different aroma types were screened by combined using flavoromics and machine learning. A total of 108 volatile compounds were identified and 100 kinds of them were accurately quantified, and 38 compounds out of them were with odorant activity value ≥1. The 33 peanut oils presented varied intensity of 'fresh peanuts', 'roasted nut', 'burnt', 'over-burnt', 'sweet', 'peanut butter-like', 'puffed food' and 'exotic flavor', and could be classified into four aroma types, namely raw, light, thick and salty. Partial least squares regression analysis, random forest and classification regression tree revealed that 2-acetyl pyrazine had a negative effect on 'fresh peanuts' and could distinguish raw flavor samples well; 2-methylbutanal and 4-vinylguaiacol were key compounds of 'roasted nut' and had significant differences (P < 0.0001) in thick and raw flavor samples; furfural contributed to the 'puffed food' as well as key compound of salty flavor.

Comparative effects of W/O and O/W emulsions on the physicochemical properties of silver carp surimi gels

The comparative effects of water-in-oil (W/O) and oil-in-water (O/W) emulsions on the physicochemical characteristics of silver carp surimi gels were investigated. The breaking force of surimi gels was 188.72 g, which decreased with increasing W/O emulsion but remained constant by adding O/W emulsion. The hardness decreased with increasing W/O emulsion, while the other parameters to TPA maintained constant whether the W/O or O/W emulsion was added. The yellowness value of surimi gels was 1.30, which increased with increasing W/O emulsion while remained constant after adding O/W emulsion. The water-holding capacity of surimi gels was invariant when emulsions increased. After emulsions added to surimi gels, no changes in the surimi protein interactions were found in electrophoretic patterns and Fourier transform infrared spectra. The increasing W/O emulsion enlarged the droplet size of oil and then destroyed the surimi gel network structure, while the oil droplets were evenly dispersed with increasing O/W emulsion.

Effects of different extraction methods on volatile profiles of flaxseed oils

To investigate the effects of different extraction methods on volatile compounds in flaxseed oil (FSO), we first carried out solvent extraction, cold pressing, and hot pressing treatments of flaxseed [Linum usitatissimum (L.)], then applied the headspace-gas chromatography-ion mobility spectrometry technology to identify the volatile substance compositions, and established flavor fingerprints of solvent-extracted FSO, cold-pressed FSO, and hot-pressed FSO. In total, 81 volatile compounds were detected, including 27 aldehydes, 14 alcohols, 13 ketones, 9 heterocycles, 8 esters, 5 acids, 4 hydrocarbons, and 1 sulfur compound (dimethyl disulfide). Extraction methods had a great influence on the volatile profile of FSO. Solvent-extracted FSO had more sweet, mild, floral, and sour volatile profiles, cold-pressed FSO had stronger volatile profiles of winey, spicy, and fatty, and hot-pressed FSO had green, grass, and plastic volatile profiles. Principal component analysis and Euclidean distance demonstrated that the volatile compounds of three FSO samples could be clearly distinguished. Of note, the cold-pressed FSO and hot-pressed FSO had similar volatile profiles, and they were different from solvent-extracted FSO. This study could provide some guidance for improving the flavor quality of FSO and selecting the proper extraction method for FSO productions. PRACTICAL APPLICATION: Practical Application: This study shows extraction methods significantly affect the formation of aroma characteristics in flaxseed oil (FSO), and it provides theoretical guidance for production to use the appropriate extraction methods for high-quality FSO.

A review of different frying oils and oleogels as alternative frying media for fat-uptake reduction in deep-fat fried foods

Purpose

This review aims to examine the potential of oleogels as a frying medium to decrease oil absorption during deep-frying and enhance the nutritional and energy content of foods. By investigating the factors influencing oil incorporation during deep-frying and examining the application of oleogels in this process, we seek to provide insights into using oleogels as an alternative to traditional cooking oils.

Scope

Deep-frying, a widely used cooking method, leads to the retention of large amounts of oil in fried food, which has been associated with health concerns. To address this issue, researchers have investigated various methods to minimize oil absorption during frying. One promising approach is the use of oleogels, which are thermo-reversible, three-dimensional gel networks formed by entrapment of bulk oil with a low concentration (<10% of weight) of solid lipid materials known as oleogelators. This review will focus on the following aspects: a) an overview of deep-fried foods, b) factors influencing oil uptake and underlying mechanisms for oil absorption during deep-frying, c) the characterization and application of different frying oils and their oleogels in deep-fried foods, d) components of the oleogel system for deep-frying, and e) the health impact, oxidative stability, and sensory acceptability of using oleogels in deep-frying.

Key findings

The review highlights the potential of oleogels as a promising alternative frying medium to reduce fat absorption in deep-fried foods. Considering the factors influencing oil uptake during deep-frying, as well as exploring the properties and applications of different frying oils and their oleogels, can result in improved product qualities and heightened consumer acceptance. Moreover, oleogels offer the advantage of lower fat content in fried products, addressing health concerns associated with traditional deep-frying methods. The capacity to enhance the nutritional and energy profile of foods while preserving sensory qualities and oxidative stability positions oleogels as a promising choice for upcoming food processing applications.

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 ∼ 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.

Tiger nut (Cyperus esculentus L.) oil: A review of bioactive compounds, extraction technologies, potential hazards and applications

Tiger nut is a tuber of a plant native in the Mediterranean coastal countries, which is of great interest in food industry due to its richness in carbohydrates, lipids, starches, minerals, etc. Recent studies have focused on the analysis of the phytochemical composition of tiger nut, including six essential nutrients, polyphenols, and the extraction of proteins, starches, and phenolic compounds from the by-products of tiger nut milk 'horchata'. Few works were focused on the possibility of using tiger nut oil, a nutritious oil comparable to olive oil, as an edible oil. Therefore, this review discussed some extraction technologies of tiger nut oil, and their effects on the properties of oil, such as bioactive compounds, oxidative stability and potential hazards. The information on the emerging applications of tiger nut oil was summarized and an outlook on the utilization of tiger nut oil by-products were also reviewed.

A novel whole peanut butter refined by stirred media mill: The size, microstructure, rheology, nutrients, and flavor

A novel whole peanut butter (PB) was developed using an emerging technology called stirred media mill (SMM). The impact of SMM on the size, microstructure, rheology, nutrient, and flavor of PB was investigated. The SMM treatment significantly decreased the particle size of PB, damaged cell structure, and released the oil body from cells. The apparent viscosity of PB decreased with the grinding process. Visual inspection revealed that the colloidal stability of PB was improved. The fatty acid composition was not affected by the grinding process. However, the tocopherol contents of the extracted oil slightly increased. Electronic nose and GC-MS analysis indicated that SMM could alter the flavor of PB after grinding for 45 min. Overall, SMM was a potential process technology to manufacture stable nut butter with smooth texture and delightful flavor profile.

Comparative Analysis of Key Odorants and Aroma Characteristics in Hot-Pressed Yellow Horn (Xanthoceras sorbifolia bunge) Seed Oil Via Gas Chromatography-Ion Mobility Spectrometry and Gas Chromatography-Olfactory-Mass Spectrometry

Volatile compounds (VOCs) present in the oil extracted from yellow horn seeds were first analyzed using GC-IMS and GC-O-MS at varying roasting temperatures. A total of 97 VOCs were detected using GC-IMS, while 77 were tentatively identified using GC-O-MS. Moreover, both methods allowed the identification of 24 VOCs, of which the type of aldehydes is the most abundant. Combining the results of GC-IMS, GC-O-MS, OAVs, and VIP, it was concluded that hexanal, 2,5-dimethylpyrazine, heptanal, 2-pentylfuran, 1-hexanol, and 1-octen-3-ol were the key aroma compounds. The PLS-DA and OPLS-DA models have demonstrated the ability to discriminate between different oil roasting temperatures with high accuracy. The roasting temperature of 160 °C was found to yield the highest content of main aroma substances, indicating its optimality for yellow horn seed oil production. These findings will prove beneficial for optimizing industrial production and enhancing oil aroma control.

Effect of Extraction Methods on the Physicochemical Properties, Chemical Composition, and Antioxidant Activities of Samara Oil

Samara oil (Elaeagnus mollis Diels kernel oil) exhibits diverse healthy functions; however, the effect of extraction on its quality is still unclear. The present study was undertaken to evaluate the effect of extraction methods (solvent extraction: ethyl acetate, acetone, n-hexane, and petroleum ether; mechanical extraction: hot-pressing and cold-pressing) on the color, acid value, peroxide value, fatty acid composition, bioactive compounds, antioxidant activities, and oxidative stability index of samara oil obtained from Elaeagnus mollis Diels kernels. The results indicated that extraction methods affected the physicochemical properties, chemical composition, and antioxidant activities of samara oil except for fatty acid composition and γ-tocopherol. The highest values of bioactive compounds including polyphenols (140.27 mg gallic acid equivalent (GAE)/kg) and carotenoids (42.95 mg/kg) were found in samara oil extracted with acetone. The values of 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) assays, as well as oxidative stability index (OSI), were the highest in this oil. Correlation analysis results demonstrated that DPPH, ABTS, and OSI of samara oil were positively correlated with polyphenols and carotenoids. After evaluation, acetone could be used to extract samara oil. The study provides new information on the samara oil process.

The Relationship between Microbial Community Succession and Flavor Formation during the Natural Fermentation of Hongqu sufu

To study the diversity of microbial flora in Hongqu sufu and analyze the characteristics of special flavor compounds, this study took self-made Hongqu sufu as the research object. Dynamic changes in sufu during fermentation were studied. High-throughput sequencing (HTS) was used to analyze changes in the diversity of fungal and bacterial communities during fermentation. The results showed that at the phylum level, the dominant fungal phyla were identified, Mucormyces and Ascomycetes. The dominant bacterial phyla were Proteobacteria and Firmicutes. At the genus level, the dominant fungal genera were identified as Actinomucor, Monascus, and Aspergillus. The dominant bacterial genera were Pseudomonas, Aneurimibacillus, Sphingobacterium, and Bacillus. Headspace solid-phase microextraction gas chromatography-mass spectrometry (HS-SPME-GC-MS) combined with technology that can dynamically change flavor compounds was explored to investigate the correlation between microbiota and flavor compounds. In different stages of fermentation, 75 main volatile organic compounds were identified, including seven alcohols, four acids, 16 alkanes, 14 olefins, seven kinds of aldehydes, two kinds of ketones, 10 kinds of esters, one kind of phenol, one kind of sulfur-containing compound, one benzene, and 12 other compounds. The correlation analysis between flora and flavor compounds showed that the fungi genera Alternaria and Pichia were significantly correlated with most flavor compounds. Bacteria genera including Weissella, Hafnia-Obesumbacterium, and Leuconostoc had a strong positive correlation with ethyl oleate.

Widely targeted metabolomic approach reveals dynamic changes in non-volatile and volatile metabolites of peanuts during roasting

Roasting influences the color, flavor, and antioxidant activities of peanuts. However, the biochemical mechanisms that occur during roasting are not well known. In this study, the dynamic changes in non-volatile and volatile metabolites in raw, light, and dark roasted peanuts were investigated using ultra-performance liquid chromatography with a widely targeted metabolomic approach based on tandem mass spectrometry and gas chromatography-mass spectrometry. A total of 738 non-volatile metabolites (comprising 12 subclasses) and 71 volatile metabolites (comprising 14 subclasses) were identified in raw and roasted peanuts. Significantly different non-volatile and volatile metabolites were detected. Among them, amino acids, sugars, and lipids (lysophosphatidylethanolamines and oxidized fatty acids) were found to be highly linked to flavor formation. In addition, the enhanced color and antioxidant activities of peanuts were attributed to the Maillard reaction and sugar degradation. These results provide comprehensive insights into the quality improvements of peanuts during roasting.

Effect of transglutaminase-catalyzed crosslinking behavior on the quality characteristics of plant-based burger patties: A comparative study with methylcellulose

Transglutaminase (TGase) is gaining increasing recognition as a novel and healthier bio-binder for meat analogs. This work focused on the TGase-induced crosslinking behaviors, and then evaluated the difference in quality characteristics (Texture, water distribution, cooking properties, volatile flavor and protein digestibility) of peanut protein-based burger patties treated with TGase and traditional binder (methylcellulose, MC). TGase-catalyzed crosslinking, enabling amino acids to participate in the formation of covalent bonds rather than non-covalent bonds, and promoted the formation of protein aggregates and dense gel networks by changing the protein structure, ultimately improving the quality characteristics of burger patties. Compared with the TGase treatment, MC-treated burger patties showed a greater texture parameter, lower cooking loss, higher flavor retention but a lower degree of digestibility. The findings will contribute to a better understanding of the roles of TGase and traditional binders in plant-based meat analogs.

Research on the Differences in Phenotypic Traits and Nutritional Composition of Acer Truncatum Bunge Seeds from Various Regions

Acer truncatum Bunge (ATB) is an excellent edible woody oil tree species since it bears a huge amount of fruit and has strong adaptability to be widely cultivated. Selecting an optimal cultivation region for ATB is crucial to improving China's woody oil industrialization. Chemical analysis, correlation analysis, and affiliation function values were used in the present research to systematically analyze the phenotypic traits, organic compound content, and seed oil chemical composition of the seeds of ATB from nine regions. The average contents of oil, protein, and soluble sugar in ATB seeds were 43.30%, 17.40%, and 4.57%, respectively. Thirteen fatty acids were identified from ATB seed oil, the highest content of which was linoleic acid (37.95%) and nervonic acid content was 5-7%. The maximum content of unsaturated fatty acids in ATB seed oil was 90.09%. Alpha-tocopherol content was up to 80.75 mg/100 g. The degree of variation in seed quality traits (25.96%) was stronger than in morphological traits (14.55%). Compared to environmental factors, the phenotypic traits of seeds contribute more to organic compounds and fatty acids. Combining the values of the indicator affiliation functions, Gilgarang, Tongliao, Inner Mongolia was selected as the optimal source of ATB for fruit applications from nine regions.

Potential use of saline resources for biofuel production using halophytes and marine algae: prospects and pitfalls

There exists a global challenge of feeding the growing human population of the world and supplying its energy needs without exhausting global resources. This challenge includes the competition for biomass between food and fuel production. The aim of this paper is to review to what extent the biomass of plants growing under hostile conditions and on marginal lands could ease that competition. Biomass from salt-tolerant algae and halophytes has shown potential for bioenergy production on salt-affected soils. Halophytes and algae could provide a bio-based source for lignoceelusic biomass and fatty acids or an alternative for edible biomass currently produced using fresh water and agricultural lands. The present paper provides an overview of the opportunities and challenges in the development of alternative fuels from halophytes and algae. Halophytes grown on marginal and degraded lands using saline water offer an additional material for commercial-scale biofuel production, especially bioethanol. At the same time, suitable strains of microalgae cultured under saline conditions can be a particularly good source of biodiesel, although the efficiency of their mass-scale biomass production is still a concern in relation to environmental protection. This review summaries the pitfalls and precautions for producing biomass in a way that limits environmental hazards and harms for coastal ecosystems. Some new algal and halophytic species with great potential as sources of bioenergy are highlighted.

Accurate and non-destructive monitoring of mold contamination in foodstuffs based on whole-cell biosensor array coupling with machine-learning prediction models

Mold contamination in foodstuffs causes huge economic losses, quality deterioration and mycotoxin production. Thus, non-destructive and accurate monitoring of mold occurrence in foodstuffs is highly required. We proposed a novel whole-cell biosensor array to monitor pre-mold events in foodstuffs. Firstly, 3 volatile markers ethyl propionate, 1-methyl-1 H-pyrrole and 2,3-butanediol were identified from pre-mold peanuts using gas chromatography-mass spectrometry. Together with other 3 frequently-reported volatiles from Aspergillus flavus infection, the volatiles at subinhibitory concentrations induced significant but differential response patterns from 14 stress-responsive Escherichia coli promoters. Subsequently, a whole-cell biosensor array based on the 14 promoters was constructed after whole-cell immobilization in calcium alginate. To discriminate the response patterns of the whole-cell biosensor array to mold-contaminated foodstuffs, optimal classifiers were determined by comparing 6 machine-learning algorithms. 100 % accuracy was achieved to discriminate healthy from moldy peanuts and maize, and 95 % and 98 % accuracy in discriminating pre-mold stages for infected peanuts and maize, based on random forest classifiers. 83 % accuracy was obtained to separate moldy peanuts from moldy maize by sparse partial least square determination analysis. The results demonstrated high accuracy and practicality of our method based on a whole-cell biosensor array coupling with machine-learning classifiers for mold monitoring in foodstuffs.

Antioxidant Properties of Protein-Rich Plant Foods in Gastrointestinal Digestion—Peanuts as Our Antioxidant Friend or Foe in Allergies

Thermally processed peanuts are ideal plant models for studying the relationship between allergenicity and antioxidant capacity of protein-rich foods, besides lipids, carbohydrates and phytochemicals. Peanut is highly praised in the human diet; however, it is rich in allergens (>75% of total proteins). One-third of peanut allergens belong to the products of genes responsible for the defence of plants against stress conditions. The proximate composition of major peanut macromolecules and polyphenols is reviewed, focusing on the identity and relative abundance of all peanut proteins derived from recent proteomic studies. The importance of thermal processing, gastrointestinal digestion (performed by INFOGEST protocol) and their influence on allergenicity and antioxidant properties of protein-rich plant food matrices is elaborated. Antioxidant properties of bioactive peptides from nuts were also considered. Moreover, there are no studies dealing simultaneously with the antioxidant and allergenic properties of protein- and polyphenol-rich foods, considering all the molecules that can significantly contribute to the antioxidant capacity during and after gastrointestinal digestion. In summary, proteins and carbohydrates are underappreciated sources of antioxidant power released during the gastrointestinal digestion of protein-rich plant foods, and it is crucial to decipher their antioxidant contribution in addition to polyphenols and vitamins before and after gastrointestinal digestion.

Nutraceutical and Pharmaceutical Behavior of Bioactive Compounds of Miracle Oilseeds: An Overview

India plays an important role in the production of oilseeds, which are mainly cultivated for future extraction of their oil. In addition to the energic and nutritional contribution of these seeds, oilseeds are rich sources of bioactive compounds (e.g., phenolic compounds, proteins, minerals). A regular and moderate dietary supplementation of oilseeds promotes health, prevents the appearance of certain diseases (e.g., cardiovascular diseases (CVDs), cancers) and delays the aging process. Due to their relevant content in nutraceutical molecules, oilseeds and some of their associated processing wastes have raised interest in food and pharmaceutical industries searching for innovative products whose application provides health benefits to consumers. Furthermore, a circular economy approach could be considered regarding the re-use of oilseeds’ processing waste. The present article highlights the different oilseed types, the oilseeds-derived bioactive compounds as well as the health benefits associated with their consumption. In addition, the different types of extractive techniques that can be used to obtain vegetable oils rich from oilseeds, such as microwave-assisted extraction (MAE), ultrasonic-assisted extraction (UAE) and supercritical fluid extraction (SFE), are reported. We conclude that the development and improvement of oilseed markets and their byproducts could offer even more health benefits in the future, when added to other foods.

Characterization of Volatile Flavor Compounds in Supercritical Fluid Separated and Identified in Gurum (Citrulluslanatus Var. colocynthoide) Seed Oil Using HSME and GC-MS

In this study, the volatile compound profiles of gurum seed oil were determined using two methods: supercritical CO₂ extraction (SFE) and the screw press process (SPP). For volatile compounds extraction and identification, headspace solid-phase micro-extraction (HS-SPME) and GC-MS were used, respectively. A total number of 56 volatile compounds were revealed and identified in oil extracted by SFE, while only 40 compounds were detected in extracted oil by SPP. Acids, aldehydes, esters, ketones, furans, and other components were present in the highest ratio in oil extracted by SFE. In contrast, alcohols and alkenes were found in the highest proportion in oil extracted by SPP. In this study, it was observed that SFE showed an increase in the amounts of volatile compounds and favorably impacted the aroma of gurum seed oil. The results reveal that different extraction methods significantly impact the volatile components of gurum seed oil, and this study can help evaluate the quality of the oil extracted from gurum seeds.

Quality evaluation of oil by cold-pressed peanut from different growing regions in China

In this study, twenty-six peanut varieties and their cold-pressed oils from eleven provinces in China were investigated for their oil content, acid value, peroxide value, fatty acid profiles, bioactive constituents, and induction period (IP) of lipid oxidation. Meanwhile, the effect of the geographical origin of peanut on the quality of cold-pressed peanut oils (CPOs) was studied. The average acid value of CPOs in southern China was higher than that in northern China (0.49 mg KOH/g versus 0.22 mg KOH/g, p > .05). In addition, the average of oleic acid content, ratio of oleic acid to linoleic acid (O/L), and IP were also higher in southern China than that in northern China (p < .05). However, the average content of campesterol, β-sitosterol, total phytosterol, linoleic acid, and ratio of unsaturated fatty acid to saturated fatty acid (UFA/SFA) exhibited reverse results (p < .05). At last, the comprehensive evaluation of CPOs based on principal component analysis (PCA) was performed. In all samples, Silihong from Liaoning province, northern China was No.1, and Zhonghua 21 from Xiaogan City, Hubei Province was No.4 which was the first one from southern China. Moreover, heat map clustering analysis further revealed the differences and similarities among different samples, and those results were in accordance with the comprehensive evaluation results.

Simple and Rapid Method for the Quantitation of Trace-Level 3-Alkyl-2-methoxypyrazines in Fragrant Vegetable Oils by Gas Chromatography-Tandem Mass Spectrometry

3-Alkyl-2-methoxypyrazines (MPs) are characteristic aroma compounds found in fragrant vegetable oils, a type of specially processed oils with enhanced flavor. MP contents in these oils are usually at trace level, which makes their quantification a big challenge. In this work, we describe an optimized approach with a double-step acid/alkali extraction for the analysis of such compounds, namely, 3-isopropyl-2-methoxypyrazine, 3-isobutyl-2-methoxypyrazine, and 3-sec-butyl-2-methoxypyrazine, in those fragrant oils using gas chromatography-tandem mass spectrometry (GC-MS/MS). The sample preparation conditions including selections and percentages of acids, alkalis, and extraction solvents, as well as the stability of MPs, were optimized and examined. Method validation was conducted with a good linearity (r² > 0.999), and average recoveries between 93.9 and 109.3% were achieved. The limit of detection ranged from 0.2 to 0.4 μg/kg, and the relative standard deviations varied from 0.4 to 12.2% for samples spiked with the MPs at different concentrations. Overall, the method satisfactorily meets the requirements for the measurement of trace-level MPs in the fragrant vegetable oils via odor activity value calculation, and the results indicate that the improved acid/alkali extraction method is suitable for the routine analysis of MPs in those vegetable oils.

Recent Advances for the Developing of Instant Flavor Peanut Powder: Generation and Challenges

Instant flavor peanut powder is a nutritional additive that can be added to foods to impart nutritional value and functional properties. Sensory acceptability is the premise of its development. Flavor is the most critical factor in sensory evaluation. The heat treatment involved in peanut processing is the main way to produce flavor substances and involves chemical reactions: Maillard reaction, caramelization reaction, and lipid oxidation reaction. Peanut is rich in protein, fat, amino acids, fatty acids, and unsaturated fatty acids, which participate in these reactions as volatile precursors. N-heterocyclic compounds, such as the pyrazine, are considered to be the key odorants of the “baking aroma”. However, heat treatment also affects the functional properties of peanut protein (especially solubility) and changes the nutritional value of the final product. In contrast, functional properties affect the behavior of proteins during processing and storage. Peanut protein modification is the current research hotspot in the field of deep processing of plant protein, which is an effective method to solve the protein denaturation caused by heat treatment. The review briefly describes the characterization and mechanism of peanut flavor during heat treatment combined with solubilization modification technology, proposing the possibility of using peanut meal as material to produce IFPP.

Effects of roasting and deodorisation on 3-monochloropropane-1, 2-diol esters, 3, 4-benzopyrene and trans fatty acids in peanut oil

Hazardous substances are readily produced during roasting and deodorisation in the preparation of peanut oil. The aim of this work was to investigate the variation of 3-monochloropropane-1, 2-diol ester (3-MCPDE), 3, 4-benzopyrene (BaP) and trans fatty acid (TFA) contents in the roasting and deodorisation segments of peanut oil production process. Roasting temperatures and durations significantly affected the contaminants contents in peanut oil; they increased significantly at a roasting temperature >210°C and time >60 min. In the deodorisation segment, the BaP and TFA contents were over the standard limits at a deodorisation temperature >210°C and time >140 min. Analysis showed that 3-MCPDE was significantly correlated with the formation of C18:2T (r = 0.979) and there was a linear relationship between BaP and C18:1T (Y = 0.509 C18:1T). This information will provide guidance for the precise and appropriate processing of peanut oil.

Analyzing the Effect of Baking on the Flavor of Defatted Tiger Nut Flour by E-Tongue, E-Nose and HS-SPME-GC-MS

In order to screen for a proper baking condition to improve flavor, in this experiment, we analyzed the effect of baking on the flavor of defatted tiger nut flour by electronic tongue (E-tongue), electronic nose (E-nose) and headspace solid-phase microextraction gas chromatography-mass spectrometry (HS-SPME-GC-MS). According to E-tongue and E-nose radar plots and principal component analysis (PCA), baking can effectively change the taste and odor of defatted tiger nut flour, and the odors of samples with a baking time of >8 min were significantly different from the original odor of unbaked flour. Moreover, bitterness and astringency increased with longer baking times, and sweetness decreased. HS-SPME-GC-MS detected a total of 68 volatile organic compounds (VOCs) in defatted tiger nut flour at different baking levels, and most VOCs were detected at 8 min of baking. Combined with the relative odor activity value (ROAV) and heat map analysis, the types and contents of key flavor compounds were determined to be most abundant at 8 min of baking; 3-methyl butyraldehyde (fruity and sweet), valeraldehyde (almond), hexanal (grassy and fatty), and 1-dodecanol, were the key flavor compounds. 2,5-dimethyl pyrazine, and pyrazine, 2-ethylalkyl-3,5-dimethyl- added nutty aromas, and 1-nonanal, 2-heptanone, octanoic acid, bicyclo [3.1.1]hept-3-en-2-ol,4,6,6-trimethyl-, and 2-pentylfuran added special floral and fruity aromas.

Effect of oilseed roasting on the quality, flavor and safety of oil: A comprehensive review

Roasting is widely applied in oil processing and employs high temperatures (90-260 °C) to heat oilseeds evenly. Roasting improves the extraction yield of oil by the generation of pores in the oilseed cell walls, which facilitates the movement of oil from oilseed during subsequent extraction. It also affects the nutritional value and palatability of the prepared oil, which has attracted consumers' attention. An appropriate roasting process contributes to better extraction of bioactive compounds, particularly increasing the total polyphenol content in the oil. Correspondingly, extracted oil exhibits higher antioxidant capacity and oxidative stability after roasting the oilseeds due to better extraction of endogenous antioxidants and the generation of Maillard reaction products. Furthermore, roasting process is critical for the formation of aroma-active volatiles and the improvement of desired sensory characteristics, so it is indispensable for the production of fragrant oil. However, some harmful components are inevitably generated during roasting, including oxidation products, polycyclic aromatic hydrocarbons, and acrylamide. Monitoring and controlling the concentrations of harmful compounds in the oil during the roasting process is important. Therefore, this review updates how roasting affect the quality and safety of oils and provides useful insight into regulation of the roasting process based on bioactive compounds, sensory characteristics, and safety of oils. Further research is required to assess the nutritional value and safety of roasted oils in vivo and to develop a customized roasting process for various oilseeds to produce good-quality oils.