Degradation Products Of Fatty Acids Research Articles

FAMS-A Targeted Fatty Acid Mass Spectrometry Method for Monitoring Free Fatty Acids from Polysorbate Hydrolysis.

Polysorbates are the predominant surfactants used to stabilize protein formulations. Unfortunately, polysorbates can undergo hydrolytic degradation, which releases fatty acids that can accumulate to form visible particles. The detection and quantitation of these fatty acid degradation products are critical for assessing the extent of polysorbate degradation and the associated risks of particle formation. We previously developed a user-friendly mass spectrometric method called Fatty Acids by Mass Spectrometry (FAMS) to quantify the free fatty acids. The FAMS method was validated according to ICH Q2 (R1) guidelines and is suitable for a wide range of products, buffers and protein concentrations. The end-to-end workflow can be automated from sample preparation to data analysis. To broaden method accessibility, the QDa detector selected for fatty acid measurement does not require specific mass spectrometry experience. We provide here a detailed procedure for both manual and automated sample preparation for high-throughput analysis. In addition, we highlight in this protocol the critical operational details, procedural watchouts and troubleshooting tips to support the successful execution of this method in another laboratory.

Physicochemical property, volatile flavor quality, and microbial community composition of Jinhua fatty ham and lean ham: A comparative study.

The physicochemical property, volatile flavor compounds, and microbial community structure of Jinhua fatty ham (FH) and lean ham (LH) were investigated and compared by high-throughput sequencing and HS-GC-IMS. Results showed that FH had higher pH and slightly lighter and yellower color than LH. Meanwhile, 33 volatile flavor compounds were identified from FH and LH, among which LH showed higher abundance of total alcohols and acids, but FH had generally richer aldehydes, ketones, esters, heterocyclic, and sulfur-containing compounds. Moreover, FH and LH did not have significant difference in α-diversity of bacterial community, but LH presented a much lower α-diversity of fungal community than FH. Besides, the dominant microorganisms (relative abundance >2%) in FH were Ruminococcaceae UCG-005, Staphylococcus, Ruminococcaceae UCG-014, Meyerozyma, and Aspergillus at the genus level, while in LH were Staphylococcus, Psychrobacter, Halomonas, Propionicicella, Ruminococcaceae UCG-005, Meyerozyma, Yamadazyma, and Aspergillus. Furthermore, the analysis of Pearson's correlation and metabolic network confirmed that the discriminative flavor compounds of FH were mainly β-oxidation and degradation products of fatty acids, while those of LH were mostly derived from the Strecker reaction or microbial metabolism of amino acids. The present study could help understand the potential pathway of characteristic microorganisms affecting flavor formation of fat-deficient dry-cured hams and provide theoretical supports for developing healthier fermented meat products.

High throughput FAMS – A fatty acid mass spectrometry method for monitoring polysorbate hydrolysis in QC

Surfactant degradation in biopharmaceuticals has recently gained significant attention in the pharmaceutical industry. Specifically, hydrolytic degradation of polysorbates, leading to the release of free fatty acids potentially forming visible particles, is a key theme in technical development. To address this emerging topic, we present the development of a fully automated liquid-chromatography single quad mass detector method for the quantification of free fatty acids in biopharmaceuticals. For the first time, we have quantified the longer chain fatty acid degradation products of polysorbate, palmitic and stearic acid, allowing reliable detection and early critical insights for process improvements. This high-throughput method was validated underlining its robust performance in an interlaboratory trial as well as high flexibility allowing different robotic platforms and preparation techniques. The combination of automated sample preparation, separation by liquid chromatography and single quad mass detection makes the validated fatty acid mass spectrometry assay ready for routine use in a regulated environment.

Phenylalanine induces mango fruit resistance against chilling injuries during storage at suboptimal temperature

Cold is the best means of prolonging fruit storage. However, tropical fruit are susceptible to cold storage. The mode of action of mango fruit tolerance to suboptimal cold temperature of 7 or 10 °C after postharvest application of 8 mM phenylalanine was investigated using transcriptomic and metabolomic analyses of mango fruit during suboptimal cold storage. Phenylalanine-treated fruit had less chilling injuries—black spot and pitting electrolyte leakage,—and reduced decay after suboptimal cold storage. Phenylalanine treatment induced genes related to plant–pathogen interactions, plant hormone signal transduction, and the phenylpropanoid pathway, increasing the levels of the flavonoids quercetin and kaempferol glycosides and anthocyanins, and antioxidant content. Reduced oxidation led to lower lipid peroxidation, and a reduction in fatty acid-degradation products, e.g., volatile aldehydes. Treatment with phenylalanine, therefore, enhances chilling tolerance of mango fruit through regulation of metabolic and defense-related pathways, maintaining high levels of flavonoids, and antioxidants enzyme activity, and reducing H2O2 content, lipid peroxidation, and volatile aldehydes.

Novel Ambient Oxidation Trends in Fingerprint Aging Discovered by Kendrick Mass Defect Analysis.

A Kendrick mass defect (KMD) plot is an efficient way to disperse complex high-resolution mass spectral data in a visually informative two-dimensional format which allows for the rapid assignment of compound classes that differ by heteroatom content and/or unsaturation. Fingerprint lipid oxidation has the potential to be used to estimate the time since deposition of a fingerprint, but the mass spectra become extremely complex as the lipids degrade. We apply KMD plot analysis for the first time to sebaceous fingerprints aged for 0–7 days to characterize lipid degradation processes analyzed by MALDI-MS. In addition to the ambient ozonolysis of fingerprint lipids previously reported, we observed unique spectral features associated with epoxides and medium chain fatty acid degradation products that are correlated with fingerprint age. We propose an ambient epoxidation mechanism via a peroxyl radical intermediate and the prevalence of omega-10 fatty acyl chains in fingerprint lipids to explain the features observed by the KMD plot analysis. Our hypotheses are supported by an aging experiment performed in a sparse ozone condition and on-surface Paternò–Büchi reaction. A comprehensive understanding of fingerprint degradation processes, afforded by the KMD plots, provides crucial insights for considering which ions to monitor and which to avoid, when creating a robust model for time since deposition of fingerprints.

Chemo-sensory characterization of aroma active compounds of native oak wood in relation to their geographical origins

Oak wood contains aroma-active compounds that contribute significantly to the chemical structure, olfactory and gustatory qualities of alcoholic beverages and vinegars as by-products that have been either fermented and/or aged in oak barrels. The chemical composition of cooperage oak is highly variable, depending on the degree of toasting and natural seasoning. However, it is unclear whether the odor of oak varies according to different geographical regions and pedoclimatic conditions. Especially in view of the actual challenges in forestry in relation to climate change, the present study aimed at elucidating the odorous constituents of nine natural oak samples from Germany, Austria and Hungary with respect to these influencing parameters. The odor profiles of the oaks were compared, the potent odorants were determined, and selected odorants were quantified using stable isotope dilution assays (SIDA). The majority of the identified odorants in all samples were fatty acid degradation products, followed by a series of odorants with terpenoic structure and others resulting from the degradation of lignin. Several different odorants including 2-propenoic acid and cinnamaldehyde are reported here for the first time in oaks from different growth regions. Odor activity values (OAVs), calculated based on odor thresholds (OTs) in water, revealed hexanal, (E)-2-nonenal, (Z)-3-hexenal, eugenol, vanillin, and whiskey lactone as potent odorants for the oak odor. Principal component analysis of the data obtained from sensory evaluation, comparative aroma extract dilution analysis (cAEDA) and their corresponding quantified odorants showed that the highest separation rate was obtained for Hungarian oak, whereas Austrian and Bavarian oak samples were more similar. Recombination experiments by mixing the dominant odorants in their naturally occurring concentrations revealed a good agreement of the smell properties of the model mixture with the smell of the respective original sample. These findings aimat evaluating and establishing a better understanding of the distinctive smell of oak wood and demonstrated the prospects of new oak sources.

Resolving the smell of wood - identification of odour-active compounds in Scots pine (Pinus sylvestris L.)

Being one of the most common trees in forests, Pinus sylvestris L. is a frequently used raw material for wood products. Its specific odour is, however, mostly unresolved to date. Accordingly, we investigated Scots pine wood samples grown in Germany for their main odorant composition. We employed dedicated odorant analysis techniques such as gas chromatography-olfactometry (GC-O) and aroma extract dilution analysis (AEDA) and successfully detected 44 odour-active compounds; of these, 39 substances were successfully identified by gas chromatography-mass spectrometry/olfactometry (GC-MS/O) and two-dimensional gas chromatography-mass spectrometry/olfactometry (2D-GC-MS/O). Among the main odorants found were (E,E)-nona-2,4-dienal, vanillin, phenylacetic acid, 3-phenylpropanoic acid, δ-octalactone and α-pinene, all of them having been detected with high flavour dilution factors during GC-O analyses. The majority of the identified odorants were fatty acid degradation products, plus some terpenoic substances and odorous substances resulting from the degradation of lignin. Although some of the detected substances have previously been reported as constituents of wood, 11 substances are reported here for the first time as odour-active compounds in wood, amongst them heptanoic acid, γ-octalactone, δ-nonalactone and (E,Z,Z)-trideca-2,4,7-trienal.

Impact of Added Phytosteryl/Phytostanyl Fatty Acid Esters on Chemical Parameters of Margarines upon Heating and Pan‐Frying

The effect of the thermal treatment on chemical parameters of margarines enriched with phytosteryl fatty acid esters is evaluated. Sterols, fatty acids, polar and volatile compounds, dimers, trimers, tocopherols, 3‐MCPD and glycidyl esters are analyzed applying GPC‐RI, GC‐FID, GC‐MS, and HPLC. Additionally, a Rancimat test is performed to compare the oxidative stability of margarines. This study shows that margarines with and without added phytosteryl esters are both stable at a mild temperature of 60 °C over a period of at least 7 days. On the other side after 15 min of pan‐frying at 180 °C a degradation of unsaturated fatty acids (14–47%), phytosterols (31–49%), and vitamin‐E‐active compounds (71–100%) is found. The supplementation of margarines with phytosteryl fatty acid esters have no effect on their oxidative stability during pan‐frying characterized by Rancimat test and total polar compounds. Volatile, degradation products of fatty acids as well as phytosterols, are found after pan‐frying. The composition of volatiles after pan‐frying significantly differed depends on the presence of additional PSE in margarines. For the first time, it is shown that pan‐frying with margarines over a period of 15 min results in a remarkable formation of 3‐MCPD esters while the increase of glycidyl esters is only very moderate.Practical Application: Based on this study results additional phytosteryl esters do not have antioxidative properties on margarines upon pan‐frying. What is more, they are not stable during pan‐frying at 180 °C. A significant amount of nutritionals as phytosterols, vitamin E active compounds, unsaturated fatty acids are degraded within 15 min and other undesired compounds as dimers, trimers, 3‐MCPD esters are formed. According to the research, heating at a high temperature over longer time should not be applied to this kind of product to avoid oxidation of valuable constituents and formation of degradation products. Volatile compounds which were found are characteristic for fatty acids and phytosterols degradation and can be used as indicators of margarines oxidation.The research presents chemical changes in margarines with and without additional phytosteryl/phytostanyl fatty acid esters. In the graphical abstract compounds which naturally occur in those margarines are presented and compounds which are formed after thermo‐oxidative degradation during pan‐frying.

Identification of odorants in wood of Calocedrus decurrens (Torr.) Florin by aroma extract dilution analysis and two-dimensional gas chromatography-mass spectrometry/olfactometry.

General emissions of volatile organic compounds from wood are well investigated, but only limited information is available on the odor-active substances contained therein. To close this gap, we aimed at specifically elucidating the odorous constituents of wood from incense cedar [Calocedrus decurrens (Torr.) Florin]; this material is commonly used for the production of a range of products such as pencils and interior accessories. Targeted odorant analysis requires specialized techniques combining modern odorant analytical tools with human-sensory evaluation. Following this concept, the odor profile of the wood sample was first evaluated by human-sensory analyses. Then, the most potent wood odorants were characterized by means of gas chromatography-olfactometry and ranked according to their odor potency via aroma extract dilution analysis. With use of this approach, more than 60 odorous substances were detected, and the 22 most potent odorants were successfully identified by gas chromatography-mass spectrometry/olfactometry and two-dimensional gas chromatography-mass spectrometry/olfactometry. Among the main odorants found were a series of terpenes, several degradation products of fatty acids, and a number of odorants with a phenolic core moiety. Five odorants are reported here for the first time as wood odorants, such as γ-octalactone and 3-phenylpropanoic acid; thymoquinone was demonstrated for the first time to have a pencil-like odor quality.

Volatile Compounds from Grape Skin, Juice and Wine from Five Interspecific Hybrid Grape Cultivars Grown in Québec (Canada) for Wine Production.

Developed from crosses between Vitis vinifera and North American Vitis species, interspecific hybrid grape varieties are becoming economically significant in northern areas, where they are now extensively grown for wine production. However, the varietal differences between interspecific hybrids are not well defined, nor are the relationships between hybrid grape and wine composition, which causes significant drawbacks in the development of viticulture and winemaking of northern wines. In an effort to increase our understanding of interspecific hybrids, we have characterized the free volatile compounds profiles of berries (juice and skin) and wines of five red hybrid varieties (Frontenac, Marquette, Maréchal Foch, Sabrevois and St. Croix) grown in Québec (Canada), using GC-MS(TOF)-SPME. In grapes and wines, significantly higher levels of C6 and other fatty acid degradation products (FADP) were found in Frontenac, Maréchal Foch and Marquette. Terpenes were primarily located in the skin, with Marquette showing the highest level for these compounds. Both the level of terpenes and the level of FADP in grape were strongly correlated with their respective levels in wine, as demonstrated by the redundancy analyses. Nonanal, (E,Z)-2,6-nonadienal, β-damascenone, ethyl octanoate and isoamyl acetate showed the highest OAVs in the wines of the studied varieties.

Deep‐fat frying – An ancient popular process with a lot of open questions

In 2013 the 7th International Symposium on Deep-Fat Frying took place in San Francisco. During this three-day symposium organized by the European Federation for the Science and Technology of Lipids (Euro Fed Lipid), the newest aspects on deep-fat frying were presented and discussed by more than 90 participants 1. Although deep-fat frying is a well-known and old cooking process dating back to 1600 BC, the symposium showed that still a lot of questions are open and under discussion. One reason for this is that deep-fat frying is a very dynamic process where food is immersed into hot oil resulting in drying and cooking of the food as well as deterioration of the oil with processing time. The complex processes taking place at the surface of the food but also in the oil are still not understood comprehensively. On the other side, since a remarkable part of oil is taken up by food the focus of interest is also on aspects important for maintaining the oil quality. As with the past international symposia on deep-fat frying several recommendations have been given by the participants to improve science and technology of frying as well as safety and quality of the products. The main aspects of these recommendations are risk-based research and analysis of data to identify potentially hazardous oil degradation products, development of more reliable quick tests, clear definition of specifications for frying oils, definition of a baseline for the frying operations as well as research on potential microbiological risks inherent to coated products. The participants of the 7th symposium on deep-fat frying confirmed the recommendations made in 2000 that total polar materials and polymeric triacylglycerols are the best parameters for assessing quality of used frying oil. Additionally, it was stated that peroxide value, anisidine value, and content of free fatty acids should not be used as regulatory indices to monitor and to compare the degree of degradation of frying oils. In practice, these parameters are often still in use although their degree of correlation with oil quality is weak. Also the occurrence of acrylamide in fried food based on asparagine and reducing sugars is still an issue. In 2002 the first announcement on acrylamide in fried food was a shock for the industry 2. Since this time a lot of efforts have been undertaken to minimize the formation of acrylamide while maintaining product quality. Several approaches have been found. This special issue on deep-fat frying takes the most important presentations from the 7th symposium on deep-fat frying, but also includes new aspects in seven Reviews and five Research articles. What are the degradation products of fatty acids during frying and what is their importance for health 3? How do frying conditions influence the oil uptake of food being fried 4, 5? What parameters are relevant for controlling quality of used frying oil 6? Another point coming more and more into the focus of interest is the replacement of synthetic antioxidants by antioxidants from natural sources. Consumers refuse synthetic antioxidants, therefore the search for new and applicable sources is an ongoing story. The most important sources of natural antioxidants are described in a review 7, while another paper discusses the use of antioxidants from herbs for stabilization of rapeseed oil 8. All these points cover the wide area of aspects necessary to understand the frying process better, to improve product quality and to extend service life of frying oil or fat. It was a great pleasure for us to organize and prepare this special issue on deep-fat frying and we thank all the authors for their interesting contributions and their work. We are also grateful to all the reviewers for their time-consuming, but essential, valuable, and important help. In our opinion this special issue gives excellent information on the latest developments and knowledge about deep-fat frying and we are sure that everyone will get new information from this issue of EJLST, available online at http://onlinelibrary.wiley.com/doi/10.1002/ejlt.v116.6/issuetoc. Christian Gertz Maxfry Hagen Felix Aladedunye Max Rubner-Institut Detmold Bertrand Matthäus Max Rubner-Institut Detmold

Fatty acid alterations in oils and fats during heating and frying*

Oils and fats degrade during the frying process and many reactions with numerous fatty acid alteration products have been examined. The geometrical isomerisation of double bonds leads to the formation of trans fatty acids. At frying temperatures also conjugated double bond systems are detected. The reaction of oxygen with unsaturated fatty acids results in hydroperoxides, which immediately degrade in further radical reactions at frying temperature. A set of oxygenated fatty acids has been detected including epoxy‐, keto‐ and hydroxyl fatty acids. Another route leads to β‐scission at the carbonyl‐ or the alkyl side of the oxygen bearing carbon atom in the fatty acid chain. In this case short chain fatty acids, aldehydic, keto, and hydroxyl acids appear together with volatile compounds. Also the formation of cyclic and furan fatty acids was detected. As a reaction between fatty acids also dimeric and polymerised fatty acids can be observed. Taking into account the different amounts of these fatty acid degradation products the physiological relevance has to be discussed. Due to high concentrations of dimeric and polymerised molecules these substances can lower significantly the digestibility of fried foods, while oxidised fatty acid monomers are readily absorbed and raise concern about their effect on lipid metabolism. These two different effects of altered TAGs and fatty acids have to be considered separately.

Toxigenic effects of diatoms on grazers, phytoplankton and other microbes: a review

Traditionally, diatoms have been regarded as providing the bulk of the food that sustains the marine food chain and important fisheries. However, this view was challenged almost two decades ago on the basis of laboratory and field studies showing that when copepods, the principal predators of diatoms, feed on certain diatom diets, they produce abnormal eggs that either fail to develop to hatching or hatch into malformed (i.e. teratogenic) nauplii that die soon afterwards. Over the years, many explanations have been advanced to explain the causes for reproductive failure in copepods and other marine and freshwater invertebrates including diatom toxicity, or nutritional deficiency and poor assimilation of essential compounds in the animal gut. Here we review the literature concerning the first possibility, that diatoms produce cytotoxic compounds responsible for growth inhibition and teratogenic activity, potentially sabotaging future generations of grazers by inducing poor recruitment. The cytotoxic compounds responsible for these effects are short chain polyunsaturated aldehydes (PUAs) and other oxygenated fatty acid degradation products such as hydroxides, oxo-acids, and epoxyalcohols (collectively termed oxylipins) that are cleaved from fatty acid precursors by enzymes activated within seconds after crushing of cells. Such toxins are suggested to have multiple simultaneous functions in that they not only deter herbivore feeding but some also act as allelopathic agents against other phytoplankton cells, thereby affecting the growth of competitors, and also signalling population-level cell death and termination of blooms, with possible consequences for food web structure and community composition. Some oxylipins also play a role in driving marine bacterial community diversity, with neutral, positive or negative interactions depending on the species, thereby shaping the structure of bacterial communities during diatom blooms. Several reviews have already been published on diatom-grazer interactions so this paper does not attempt to provide a comprehensive overview, but rather to consider some of the more recent findings in this field. We also consider the role of diatom oxylipins in mediating physiological and ecological processes in the plankton and the multiple simultaneous functions of these secondary metabolites.

Oxidizability of unsaturated fatty acids and of a non-phenolic lignin structure in the manganese peroxidase-dependent lipid peroxidation system

Unsaturated fatty acids have been proposed to mediate the oxidation of recalcitrant, non-phenolic lignin structures by fungal manganese peroxidases (MnP), but their precise role remains unknown. We investigated the oxidizability of three fatty acids with varying degrees of polyunsaturation (linoleic, linolenic, and arachidonic acids) by measuring conjugated dienes formation when lipid peroxidation was initiated either by MnP in the presence of Mn(II) or by chelated Mn(III). An inverse relationship between the degree of fatty acid unsaturation and the rate of peroxidation was found in both cases, but we also noted some differences between the two types of reaction. With MnP/Mn(II), the reaction developed slowly and resulted in sustained lipid peroxidation as determined by the formation of late-stage fatty acid degradation products. By contrast, the reaction with chelated Mn(III) was very rapid and did not result in the formation of these late-stage products, which suggests that this system failed to propagate the sustained radical chain reaction that is characteristic of complete lipid peroxidation. All three polyunsaturated fatty acids supported the co-oxidation of a non-phenolic lignin model compound by MnP, again showing an inverse relationship between the degree of unsaturation and reactivity, but chelated Mn(III) by itself supported only very low levels of fatty acid-mediated lignin model oxidation. These parallels in fatty acid reactivity are consistent with a reaction scheme in which Mn(III) acts as the proximal oxidant that initiates lipid peroxidation by MnP, thus generating fatty acid-derived radicals which in turn oxidize lignin structures. However, the results also suggest that the initial peroxyl radicals formed may not be the ligninolytic oxidants in this system. Instead, other radical oxidants produced during late-stage reactions of lipid peroxidation may be required.

Comparative study of volatile compounds in traditional Chinese Nanjing marinated duck by different extraction techniques

SummaryIn order to determine the entire flavour profile of traditional Chinese Nanjing marinated duck (NJMD), three sampling techniques including solid phase microextraction (SPME) with a carboxen/polydimethylsiloxane fibre, purge and trap (P&T) using Tenax‐TA absorbent and simultaneous distillation–extraction (SDE) were compared. Total 116 volatile compounds were identified by gas chromatography–mass spectrometry, authentic compounds and Krátz retention index, which included thirty‐one aldehydes, four esters, fourteen alcohols, seven acids, twenty‐five hydrocarbons, fifteen ketones, five N‐containing compounds, eight S‐containing compounds and seven furans. SPME and P&T methods provided better extraction for volatiles with low molecular masses, while SDE method extracted more heavy volatiles. In this study, SPME method was better than P&T method, and SPME with SDE method may well complement each other. Results indicated that major volatiles identified were oxidation and degradation products of fatty acids, which were considered to account for the typical flavour of traditional Chinese NJMD.

Oxylipins from freshwater diatoms act as attractants for a benthic herbivore

Lipoxygenase products (often called oxylipins) are degradation products of fatty acids. They are known to regulate many defensive and developmental pathways in plants. Among these lipoxygenase products are volatile aldehydes, that are released from wound activated diatom cells and that are potent inhibitors of mitotic prolifera- tion in sea urchin embryos. They have been shown to dramatically lower the hatching success of herbivorous copepods and therefore are considered to constitute an acti- vated defence strategy. Alternatively, lipoxygenase products might also serve as info- chemicals, especially in biofilms of benthic algae and cyanobacteria. Here, we demon- strate that the bouquet of volatile lipoxygenase products released from a benthic dia- tom (Achnanthes biasolettiana) is attractive to an herbivorous gastropod grazer (Radix ovata). The volatiles are released from the algae upon cell damage and can be utilized as food-finding cues by the herbivorous snails. In contrast to this observation, the odour bouquet from another benthic diatom species (Gomphonema parvulum) did not show any attractant activity to the snail, which is probably caused by differences in the bouquet of odorous substances released by the two diatom isolates. In contrast to G. parvulum, the odour bouquet of A. biasolettiana consisted of mono- and diunsaturated alcohols and ketones, primarily with a C8-skeleton. Most of the compounds have never before been described from diatoms. This study shows that diatom lipoxygenase prod- ucts cannot only be involved in activated defence, but can also be utilised as food-find- ing cues by herbivores. Thus, the ecological role of these volatile organic compounds can be very complex and will strongly depend on the ecological context of the chemi- cal interaction.

Changes in Volatile Compounds of Traditional Chinese Nanjing Water‐boiled Salted Duck During Processing

ABSTRACT: Volatile compounds of traditional Chinese Nanjing water‐boiled salted duck (NJWSD) during its stages of processing were analyzed by headspace solid phase microextraction (HS‐SPME) coupled with gas chromatography–mass spectrometry (GC–MS). Results showed a total of 92 tentatively identified volatile compounds of which 57 compounds were first identified in duck meat. The major volatiles identified were degradation products of fatty acids, which were considered to account for the typical flavor of duck meat. The processes of dry‐curing, brining, roasting, and boiling, all sped up lipid oxidation and degradation. Dry‐curing process generated furans, the important lipid oxidation products. Brining accelerated the formation of S‐ and N‐containing compounds. Roasting had no remarkable effect on most of the volatiles. Some S‐ and N‐containing compounds, such as 2‐methylthiophene, dimethyl trisulfide, and 2‐acetylthiazole formed during boiling combined with lipid peroxidation and degradation products could constitute the principal flavor of NJWSD. The first principal component (PC1) explained 97% of the total variance of the data and was dominated by lipid oxidation and degradation products, which were pentanal, hexanal, octanal, nonanal, and 2, 3‐octanedione. The problem using SPME for quantitation was also discussed.

Hepatotoxicity and Mechanism of Action of Haloalkanes: Carbon Tetrachloride as a Toxicological Model

The use of many halogenated alkanes such as carbon tetrachloride (CCl4), chloroform (CHCl3) or iodoform (CHI3), has been banned or severely restricted because of their distinct toxicity. Yet CCl4 continues to provide an important service today as a model substance to elucidate the mechanisms of action of hepatotoxic effects such as fatty degeneration, fibrosis, hepatocellular death, and carcinogenicity. In a matter of dose,exposure time, presence of potentiating agents, or age of the affected organism, regeneration can take place and lead to full recovery from liver damage. CCl4 is activated by cytochrome (CYP)2E1, CYP2B1 or CYP2B2, and possibly CYP3A, to form the trichloromethyl radical, CCl3*. This radical can bind to cellular molecules (nucleic acid, protein, lipid), impairing crucial cellular processes such as lipid metabolism, with the potential outcome of fatty degeneration (steatosis). Adduct formation between CCl3* and DNA is thought to function as initiator of hepatic cancer. This radical can also react with oxygen to form the trichloromethylperoxy radical CCl3OO*, a highly reactive species. CCl3OO* initiates the chain reaction of lipid peroxidation, which attacks and destroys polyunsaturated fatty acids, in particular those associated with phospholipids. This affects the permeabilities of mitochondrial, endoplasmic reticulum, and plasma membranes, resulting in the loss of cellular calcium sequestration and homeostasis, which can contribute heavily to subsequent cell damage. Among the degradation products of fatty acids are reactive aldehydes, especially 4-hydroxynonenal, which bind easily to functional groups of proteins and inhibit important enzyme activities. CCl4 intoxication also leads to hypomethylation of cellular components; in the case of RNA the outcome is thought to be inhibition of protein synthesis, in the case of phospholipids it plays a role in the inhibition of lipoprotein secretion. None of these processes per se is considered the ultimate cause of CCl4-induced cell death; it is by cooperation that they achieve a fatal outcome, provided the toxicant acts in a high single dose, or over longer periods of time at low doses. At the molecular level CCl4 activates tumor necrosis factor (TNF)alpha, nitric oxide (NO), and transforming growth factors (TGF)-alpha and -beta in the cell, processes that appear to direct the cell primarily toward (self-)destruction or fibrosis. TNFalpha pushes toward apoptosis, whereas the TGFs appear to direct toward fibrosis. Interleukin (IL)-6, although induced by TNFalpha, has a clearly antiapoptotic effect, and IL-10 also counteracts TNFalpha action. Thus, both interleukins have the potential to initiate recovery of the CCl4-damaged hepatocyte. Several of the above-mentioned toxication processes can be specifically interrupted with the use of antioxidants and mitogens, respectively, by restoring cellular methylation, or by preserving calcium sequestration. Chemicals that induce cytochromes that metabolize CCl4, or delay tissue regeneration when co-administered with CCl4 will potentiate its toxicity thoroughly, while appropriate CYP450 inhibitors will alleviate much of the toxicity. Oxygen partial pressure can also direct the course of CCl4 hepatotoxicity. Pressures between 5 and 35 mmHg favor lipid peroxidation, whereas absence of oxygen, as well as a partial pressure above 100 mmHg, both prevent lipid peroxidation entirely. Consequently, the location of CCl4-induced damage mirrors the oxygen gradient across the liver lobule. Mixed halogenated methanes and ethanes, found as so-called disinfection byproducts at low concentration in drinking water, elicit symptoms of toxicity very similar to carbon tetrachloride, including carcinogenicity.

Volatile compounds produced from monosodium glutamate in common food cooking.

A mixture of soybean oil and/or water, sugar and/or monosodium glutamate (MSG) was water-boiled or oil-heated at 100, 120, 140, 160, or 170 degrees C, respectively, and volatile compounds produced were isolated by solid-phase microextraction and then identified by GC and GC/MS. Oxidative thermal degradation products of fatty acids (OTDPFA) were the major volatile compounds detected for all water-boiled samples. When MSG and sugar were heated together, 2, 5-dimethyl pyrazine and methyl pyrazine were also detected at or after 160 min heating. Water added in soybean oil increased OTDPFA production. In oil-heated samples of soybean oil alone, soybean oil with MSG, and soybean oil with sugar, OTDPFA were also the major compounds found. The samples containing MSG also produced 2-pyrrolidone, and the samples containing sugar also produced furfural and 5-hydroxy methyl furfural. The samples containing soybean oil, sugar, and MSG produced 23 pyrazines, OTDPFA, and gamma-butyrolactone as the major volatile compounds. The contents of OTDPFA were lower in MSG plus sugar and MSG-added samples, and it is postulated that antioxidant activities were produced in cooking.

Effect of Sucrose on the Volatile Compounds Produced from Heated Glycine and Soybean Oil.

A mixture of soybean oil and glycine was heated at different temperatures for different periods. The volatile compounds produced were extracted by solid phase microextraction (SPME) and then analyzed by GC and GC-MS. 2-Pentylpyridine was the highest heterocyclic volatile compound found in the mixture. Effect of sucrose on the volatile compounds produced from heated glycine and soybean oil was also studied, furfurals, pyrroles and oxidative thermal degradation products of fatty acids (OTDPFA) were found, but no pyridines. Factors affecting the producing of 2-pentylpyridine were investigated by two sources of chemicals: one was furfural which is one of the major thermal degradation products of sucrose, and the other was OTDPFA which remains from soybean oil after heating. The results indicated that 2, 4-heptadienal induced the production of 2-ethylpyridine, but no 2-pentyl-pyridine; 2, 4-decadienal enhanced the production of 2-pentylpyridine; while all other chemicals tested in this study decreased pyridines. This suggested that oxidation-reduction potential and availability of 2, 4-decadienal affected the production of 2-pentylpyridine.