Comprehensive Two-dimensional Gas Chromatography for Analysis of the Volatile Compounds and Fishy Odor Off-flavors from Heated Rapeseed Oil

Flavor of Peanut oil: An overview of odorants, analytical techniques, factors affecting flavor characteristics

Peanut oil is appreciated for its high nutritional value and distinctive properties, also recognized as one of the major vegetable oils. Flavor is a significant characteristic that not only determines the quality of peanut oil but also significantly influences consumer acceptance. The odor-active compounds in hot-pressed and cold-pressed peanut oil, flavor analysis methods (extraction, qualitative, quantitative, and sensory evaluation), and the effects of raw materials, pretreatment techniques, and oil extraction methods on peanut oil flavor have been thoroughly examined in this review. Possible production paths of some important aroma-active chemicals are also suggested, along with a list of more than two hundred odorants found in hot and cold-pressed peanut oil from the literature. Future challenges in flavor analysis approaches lay in the successful connection of experimental data with sensory experience. Processing techniques should be further improved to produce peanut oil with superior flavor and nutrient content.

Navigating the complexity of lipid oxidation and antioxidation: A review of evaluation methods and emerging approaches

Lipid oxidative degradation contributes to the deterioration of food quality and poses potential health risks. A promising approach to counteract this is the use of plant-based antioxidants. However, accurately evaluating the antioxidant capacity and effectiveness of these compounds remains a challenge. While many rapid in vitro tests are available, they must be categorized according to their specific responses to avoid overinterpreting results. This review opens with an overview of current knowledge on lipid autoxidation and recent findings that highlight the challenges in measuring antioxidant capacity. We then examine various methods, addressing their limitations in accurately anticipating outcomes in complex compartmentalized lipid systems. The aim is to clarify the gap between predictions and real-world efficacy in final products. Additionally, the review compares the strengths and weaknesses of methods used to evaluate antioxidant capacity and assess oxidation degrees in complex environments, such as those found in food and cosmetics. Finally, new analytical techniques for multiproduct detection are introduced, paving the way for a more 'omic' and spatiotemporally defined approach.

Egg yolk phospholipids as an ideal precursor of fatty note odorants for chicken meat and fried foods: A review

Egg yolk phospholipids (PLs) have been demonstrated to generate large quantities of lipid-derived odorants, especially the fatty note odorants. Recently, egg yolk PLs have been successfully used in chicken meat and fried foods to improve aroma. This review comprehensively summarizes the properties of egg yolk PLs as precursors of fatty note odorants, including their classes, extraction, identification, oxidation, decomposition and odorant formation, applications, considerations and future prospects in the food industry. Most likely, phosphatidylcholine (PC) is the most abundant class in egg yolk PLs, and PC is more efficient than phosphatidylethanolamine in generating fatty note odorants; moreover, the predominant polyunsaturated fatty acid is linoleic acid, and its corresponding predominant hydroperoxide is 9-hydroperoxy-10,12-octadecadienoic acid during autoxidation, which is the precursor of 2,4-decadienals and 2,4-nonadienals, the key fatty note odorants. Therefore, egg yolk PLs could be an ideal precursor of fatty note odorants for chicken meat and fried foods.

Effects of High-Canolol Phenolic Extracts on Fragrant Rapeseed Oil Quality and Flavor Compounds during Frying

Fragrant rapeseed oil (FRO) is a frying oil widely loved by consumers, but its quality deteriorates with increasing frying time. In this study, the effect of high-canolol phenolic extracts (HCP) on the physicochemical properties and flavor of FRO during frying was investigated. During frying, HCP significantly inhibited the increase in peroxide, acid, p-anisidine, and carbonyl values, as well as total polar compounds and degradation of unsaturated fatty acids. A total of 16 volatile flavor compounds that significantly contributed to the overall flavor of FRO were identified. HCP was effective in reducing the generation of off-flavors (hexanoic acid, nonanoic acid, etc.) and increased the level of pleasant deep-fried flavors (such as (E,E)-2,4-decadienal). Therefore, the application of HCP has a positive effect on protecting the quality and prolonging the usability of FRO.

Management of biogenic taste and odour: From source water, through treatment processes and distribution systems, to consumers

Biogenic taste and odour (T&O) have become a global concern for water utilities, due to the increasing frequency of algal blooms and other microbial events arising from the combined effects of climate change and eutrophication. Microbially-produced T&O compounds impact source waters, drinking water treatment plants, and drinking water distribution systems. It is important to manage across the entire biogenic T&O pathway to identify key risk factors and devise strategies that will safeguard the quality of drinking water in a changing world, since the presence of T&O impacts consumer confidence in drinking water safety. This study provides a critical review of current knowledge on T&O-causing microbes and compounds for proactive management, including the identification of abiotic risk factors in source waters, a discussion on the effectiveness of existing T&O barriers in drinking water treatment plants, an analysis of risk factors for biofilm growth in water distribution systems, and an assessment of the impacts of T&O on consumers. The fate of biogenic T&O in drinking water systems is tracked from microbial production pathways, through the release of intracellular T&O by cell lysis, to the treatment of microbial cells and dissolved T&O. Based on current knowledge, five impactful research and management directions across the T&O pathway are recommended.

Flavor of rapeseed oil: An overview of odorants, analytical techniques, and impact of treatment

As one of the three major vegetable oils in the world, rapeseed oil is appreciated for its high nutritional value and characteristic flavor. Flavor is an essential attribute, determining rapeseed oil quality and consumer acceptance. The present manuscript provides a systematic literature review of recent advances and knowledge on the flavor of rapeseed oil, which focuses on aroma-active as well as off-flavor compounds, flavor analysis techniques (i.e., extraction, qualitative, quantitative, sensory, and chemometric methods), and effects of treatments (storage, dehulling, roasting, microwave, flavoring with herbs, refining, and oil heating) on flavor from sensory and molecular perspectives. One hundred thirty-seven odorants found in rapeseed oil from literature are listed and possible formation pathways of some key aroma-active compounds are also proposed. Future flavor analysis techniques will evolve toward time-saving, portability, real-time monitoring, and visualization, which aims to obtain a "complete" flavor profile of rapeseed oil. The changes of volatile compounds in rapeseed oil under different treatments are summarized in this view. Studies to elucidate the influence of different treatments on the formation of aroma-active compounds are needed to get a deeper understanding of factors leading to the variations of rapeseed oil flavor.

Evaluation of Chemical and Nutritional Changes in Chips, Chicken Nuggets, and Broccoli after Deep-Frying with Extra Virgin Olive Oil, Canola, and Grapeseed Oils

The aim of this study was to assess the food nutritional profiles of potato chips, chicken nuggets, and broccoli and their palatability after deep-frying with different oils. The trials consisted of 4 cycles of deep-frying at 180°C for 4 minutes using extra virgin olive oil (EVOO), canola, and grapeseed oils. Samples of food and oils were taken untreated and after the treatments for sensorial and chemical analysis. EVOO and canola oil deep-fried food were preferred by their colour, but canola fried food was disliked because of its flavour. Results showed that there is a transference between food and oils regarding fatty acid profile and antioxidant content as well as trans fatty acids (TFAs) and polar compounds (PCs). All food presented more antioxidants and monounsaturated fatty acids after having been cooked with EVOO than after cooking with canola and grapeseed oils. Highest PCs in food were found when using canola oil and grapeseed oils. EVOO was shown to decrease the PCs in chips and chicken nuggets. PCs were not detected in raw broccoli, and broccoli cooked in EVOO showed the lowest PCs content. Canola and grapeseed oils increased the TFAs in food, whereas EVOO decreased the TFAs in the chips and maintained the initial TFAs levels in chicken nuggets and broccoli. This study shows that EVOO improves the nutritional profile of the food when compared with canola and grapeseed oils when deep-frying without any negative impact on palatability or appearance.

Key Odorant Differences in Fragrant Brassica napus and Brassica juncea Oils Revealed by Gas Chromatography-Olfactometry, Odor Activity Values, and Aroma Recombination

Fragrant Brassica species seed oils (FBO) produced in China are mainly obtained from rapeseed (Brassica napus: B. napus) and mustard seeds (Brassica juncea: B. juncea). The characterization and differences of aroma profiles between those two species remain unclear. In this study, the volatile compounds in FBOs were systemically extracted by headspace solid-phase microextraction and solvent-assisted flavor evaporation combined with ultrasound and identified by comprehensive two-dimensional gas chromatography and time-of-flight mass spectrometry (GC×GC-TOFMS) and gas chromatography-olfactometry (GC-O). Ninety-three odorants were identified as aroma-active compounds with flavor dilution (FD) factors ranging from 1 to 6561. Moreover, 63 key compounds exhibited their odor activity values (OAVs) to be greater than 1. The oils of the two species were successfully recombinated with their key odorants. B. juncea oils presented stronger pungent-like, pickled-like, and fishy like notes compared to B. napus oils. The key odor differences were primarily attributed to the concentration of 3-butenenitrile, 4-(methylsulfanyl)butanenitrile, 5-(methylsulfanyl)pentanenitrile, 3-isothiocyanato-1-propene, 3-methyl-3-butenenitrile, isothiocyanatocyclopropane, (methylsulfanyl)acetonitrile, dimethyl sulfide, dimethyl trisulfide, and 3-(methyldisulfanyl)-1-propene. This work provides a guide for the selection of raw materials and odor markers in fragrant B. napus and B. juncea oils.

Elucidation of the Impact of Different Drying Methods on the Key Odorants of Toona sinensis (A. Juss.) Roem. Using the Sensomics Approach

The sensomics approach was applied to both green and red Toona sinensis (TS) varieties dried with different methods (freeze drying, solar drying, and oven drying) to elucidate their influences on the key odorants in TS. Odorant screening via comparative aroma dilution analysis revealed eugenol with the highest flavor dilution factor in all six samples. Quantitation of 44 odorants via stable isotope dilution assays and semiquantitation of six compounds via an internal standard method showed (E,E)-, (E,Z)-, and (Z,Z)-di-1-propenyl disulfide, dimethyl sulfide, β-ionone, eugenol, cis- and trans-2-mercapto-3,4-dimethyl-2,3-dihydrothiophene, 2- and 3-methylbutanal, and 2-isopropyl-3-methoxypyrazine with high odor activity values (OAVs) in all samples. Differences were found for (E,Z)-2,6-nonadienal, (E,E)-, (E,Z)-, and (Z,Z)-di-1-propenyl trisulfide, 3-methylnonane-2,4-dione, and (E)-2-hexenal with clearly higher OAVs in freeze-dried (FDTS) and solar-dried TS (SDTS) compared to those in oven-dried TS (ODTS). Linalool, 2-methoxyphenol, and 4-ethylphenol (the latter two only for red TS) were obtained with high OAVs only in FDTS. In general, ODTS showed the lowest OAVs, whereas FDTS as the gentlest drying process revealed the highest OAVs for most odorants and, consequently, the highest aroma quality. However, the overall aroma of SDTS did not differ too much from that of FDTS, and thus, solar drying as a much easier and cheaper technique might be the best choice.

The Blossoming of Technology for the Analysis of Complex Aroma Bouquets-A Review on Flavour and Odorant Multidimensional and Comprehensive Gas Chromatography Applications

Multidimensional approaches in gas chromatography have been established as potent tools to (almost) attain fully resolved analyses. Flavours and odours are important application fields for these techniques since they include complex matrices, and are of interest for both scientific study and to consumers. This article is a review of the main research studies in the above theme, discussing the achievements and challenges that demonstrate a maturing of analytical separation technology.

Unraveling of the Fishy Off-Flavor in Steam-Treated Rapeseed Oil Using the Sensomics Concept

The sensomics concept was applied to two steam-treated rapeseed oils, one eliciting a fishy off-flavor (OF) and the other the desired aroma attributes (PC = positive control). After screening the most important odorants via comparative aroma extract dilution analysis, identification experiments and quantitation via stable isotope dilution analysis (SIDA) using gas chromatography-mass spectrometry (GC-MS) were performed. Only five compounds differed in their concentrations by a factor ≥5. In addition, trimethylamine with an intense fishy odor quality and first overlooked by gas chromatography-olfactometry, was only present in OF and finally characterized via ion exchange chromatography and solid phase microextraction GC-MS. For data validation, recombination experiments were performed using all odorants with OAVs ≥ 1, and excellent accordance between GS and OF and their corresponding recombinates was achieved, confirming a correct characterization of all key odorants with trimethylamine as the only odorant responsible for the fishy off-flavor.

Synergetic Use of Principal Component Analysis Applied to Normed Physicochemical Measurements and GC × GC-MS to Reveal the Stabilization Effect of Selected Essential Oils on Heated Rapeseed Oil

Lipid oxidation leads to the formation of volatile compounds and very often to off-flavors. In the case of the heating of rapeseed oil, unpleasant odors, characterized as a fishy odor, are emitted. In this study, 2 different essential oils (coriander and nutmeg essential oils) were added to refined rapeseed oil as odor masking agents. The aim of this work was to determine a potential antioxidant effect of these essential oils on the thermal stability of rapeseed oil subject to heating cycles between room temperature and 180 °C. For this purpose, normed determinations of different parameters (peroxide value, anisidine value, and the content of total polar compounds, free fatty acids and tocopherols) were carried out to examine the differences between pure and degraded oil. No significant difference was observed between pure rapeseed oil and rapeseed oil with essential oils for each parameter separately. However, a stabilizing effect of the essential oils, with a higher effect for the nutmeg essential oil was highlighted by principal component analysis applied on physicochemical dataset. Moreover, the analysis of the volatile compounds performed by GC × GC showed a substantial loss of the volatile compounds of the essential oils from the first heating cycle.