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Background: The global market of plant-based milk alternatives is continually growing. Flavour and taste have a key impact on consumers' selection of plant-based beverages. Unfortunately, natural plant milks have only limited acceptance. Their typically bean-like and grassy notes are perceived as "off-flavours" by consumers, while preferred fruity, buttery, and cheesy notes are missing. In this regard, fermentation of plant milk by lactic acid bacteria (LAB) appears to be an appealing option to improve aroma and taste. Results: In this work, we systematically studied LAB fermentation of plant milk. For this purpose, we evaluated 15 food-approved LAB strains to ferment 4 different plant milks: oat milk (representing cereal-based milk), sunflower seed milk (representing seed-based milk), and pea and faba milk (representing legume-based milk). Using GC‒MS analysis, flavour changes during anaerobic fermentations were studied in detail. These revealed species-related and plant milk-related differences and highlighted several well-performing strains delivered a range of beneficial flavour changes. A developed data model estimated the impact of individual flavour compounds using sensory scores and predicted the overall flavour note of fermented and nonfermented samples. Selected sensory perception tests validated the model and allowed us to bridge compositional changes in the flavour profile with consumer response. Conclusion: Specific strain-milk combinations provided quite different flavour notes. This opens further developments towards plant-based products with improved flavour, including cheesy and buttery notes, as well as other innovative products in the future. S. thermophilus emerged as a well-performing strain that delivered preferred buttery notes in all tested plant milks. The GC‒MS-based data model was found to be helpful in predicting sensory perception, and its further refinement and application promise enhanced potential to upgrade fermentation approaches to flavour-by-design strategies. [ABSTRACT FROM AUTHOR]

This study aimed to explore the potential of a fermentation technology to reduce off-flavour perception and its underlying mechanisms. Results revealed that yeast fermentation (YF) significantly ameliorated the off-flavour of pig liver (p < 0.05). Specifically, YF pre-treatment decreased the relative abundance of α-helix and fluorescence intensity while increasing the surface hydrophobicity and S S level and loosening the microstructure of myofibrillar proteins (MPs) in pig liver. Additionally, the appropriate fermentation treatments enhanced the MP–aldehyde binding capacity by 0.25–1.30 times, demonstrating that YF-induced conformational modifications in pig liver proteins made them more prone to interacting with characteristic aldehydes. Moreover, molecular docking results confirmed that hydrophobic interactions are the primary drivers of MP–aldehyde binding. These findings suggest that YF technology holds immense promise for modulating off-flavour perception in liver products by altering protein conformation. • Yeast fermentation altered the secondary, tertiary structures and microstructure of PLPs. • Yeast fermentation enhanced the binding ability of aldehydes to PLPs. • PLPs bound to 5 characteristic aldehydes via non-covalent interactions. • The flavour regulation of PL could be achieved by fermentation. [ABSTRACT FROM AUTHOR]

Aims: Geosmin is associated with off‐flavour problems in recirculating aquaculture systems (RAS) and represents an economic problem for the aquaculture industry. This study aims at investigating factors influencing the composition of the bacterial microbiota, in particular the presence of geosmin producers and the environmental and farming factors favouring geosmin accumulation. Methods and Results: Several water quality parameters were correlated to the composition of the microbiota with special emphasis on the presence of geosmin producers within 26 different RAS from four European countries. Three novel groups of geosmin‐producing bacteria were quantified to identify potential correlations with geosmin concentration. Conclusions: The microbiome differed significantly between systems. However, phosphate levels, calcium levels and redox potential correlated to geosmin concentration in the water and the presence of the Actinomycetales geosmin‐producers but not with the presence of other groups of geosmin‐producing bacteria. Oxygen levels and conductivity were found to negatively correlate with geosmin concentration. A large proportion of the detected geosmin producers represented novel taxonomic groups not previously linked with this activity. Significance and Impact of the Study: These results improve our understanding of the diversity of microbiota in RAS and the water quality parameters favouring the populations of geosmin‐producing bacteria and the production of geosmin. [ABSTRACT FROM AUTHOR]

Summary: Yeast extract (YE) is a kind of umami additives used in fermented condiments, it also has special yeasty flavour (YF), which is not widely accepted by some consumers. In this paper, the technology of mixed microbial transformation was applied to eliminate or cover up YF during mixed fermentation. FG10, which is produced by Hubei Angel Yeast Co. Ltd, is a kind of YE that has the distinctive YF and has been applied to the market. It had good sensory evaluation after 6 h with Saccharomycopsis fibuligera and Lactococcus lactis. At 6 h, compared with single fermentation, the number of bacteria of L. lactis was enhanced by 34.28%, and the number of bacteria of S. fibuligera was reduced by 47.93%. The yeasty flavoured substances propionic acid and butyric acid were completely removed. The result of GC‐MS showed that acetal, phenyl acetaldehyde, 2,4‐dimethylbenzaldehyde, benzaldehyde, isoamyl alcohol, 5‐methyl‐2‐furan methanol, phenylethanol were generated or increased. Furthermore, the amino acids of YE were significantly different after fermentation by different microorganisms (P < 0.05), The flavour compounds and amino acids in YE before and after fermentation had closely correlation (r = 0.94), the consumption of amino acids in mixed fermentation promoted the variety of corresponding flavour compounds, which boosted the formation of free YF YE. In addition, taste substances lactic acid generated 6.27 ± 0.115 g L−1 and nucleotides improved 15.05%, which were beneficial to natural YF free seasoning with YE as raw material. [ABSTRACT FROM AUTHOR]

Summary: Packages of ready‐to‐eat (RTE) wild rocket and lettuce baby leaves were subjected during 8 days of cold storage to a chronic temperature abuse (CTA) at sub‐optimal storage temperature (10 °C) or to a short‐term (6 h) abuse at ambient temperature (STA) to evaluate the impact of two temperature abuse scenarios on gas composition within the packages, leaf sensory quality and volatile organic compounds (VOCs). In both species, the CTA scenario had a markedly higher impact on gas composition, sensory quality and off‐odour formation than the STA, and the limit of sensory acceptability was reached in the CTA scenario 4 days or more earlier than in the STA. Sulphur compounds were the main responsible for off‐odour perception in both leafy salads. Results from the present study may be useful in the assessment of critical points in the cold chain of RTE fresh produce and in prioritising actions towards improved cold‐chain management. [ABSTRACT FROM AUTHOR]

The occurrence of garlic with expressed mouldy, musty and cork taint-like off-flavour is of serious concern for the food industry as it may cause significant economic damage. In this study, we investigated a total of 42 garlic samples for their concentrations of 2,4,6-trichloroanisole (TCA) and 2,4,6-tribromoanisole (TBA). The TCA odour thresholds in two garlic matrices were determined to evaluate the impact of the TCA presence on garlic's flavour properties. While TCA was identified in more than 45% of the samples in concentrations of up to 78 µg kg−1, TBA was not detected in any of the samples. In approx. 35% of the garlic samples, the concentrations were higher than the odour threshold. It is noteworthy that garlic preparations that are to be further processed by the food industry, on average, show higher contamination rates than samples drawn from retail. The results of this survey demonstrate that it is of the utmost importance for food processing companies to perform a sensory evaluation of the garlic or garlic formulations prior to their use in order to avoid economic damage and to minimize food waste. [Display omitted] • The occurrence of 2,4,6-trichloroanisole (TCA) leads to off-flavour formation in garlic. • 2,4,6-Trichloroanisole was detected in 45% of the investigated garlic samples. • The odour activity value was higher than 1 in 35% of the samples. • The presence of TCA in garlic is of serious concern for the food industry. [ABSTRACT FROM AUTHOR]

In this study, the effect of different adsorbents on the reduction of off-flavours within a lentil protein isolate (LPI) was examined by isolating volatile compounds using headspace solid-phase microextraction (HS-SPME), and analysing with gas chromatography–mass spectrometry (GC–MS). LPIs were treated with Amberlite-XAD16N, Amberlite-XAD7HP, Amberlite-XAD4, Sepabeads-SP207 and Diaion-HP20 adsorbents, and then total peak areas of each of the flavour compounds were compared with controls. XAD16N, SP207, and HP20 were able to reduce the levels of aldehydes by 32%, 32%, and 41%, respectively. The aldehyde group of compounds (78% being hexanal) represented the major volatile compound within the LPI. All adsorbents significantly reduced 3,5-octadien-2-one by 61–92%. XAD16N and HP20 were found to be the most effective adsorbents in removing alcohols with decreases of 84% and 80%, respectively. Findings from this study could be integrated into the traditional wet extraction process to produce blander plant protein ingredients. [ABSTRACT FROM AUTHOR]

Extensive work on the chemical aspects of off-flavour in wine has been carried out by international researchers, but not as many studies focus on the organoleptic effects. This literature review therefore has a focus on the status of the sensory aspects of compounds associated with specific off-flavours in red wine, viz. three volatile phenols, as well as 2-isobutyl-3-methoxypyrazine and 2,4,6-trichloranisole. The review discusses sources and effects of the selected compounds in red wine, and what previous workers have found pertaining to the mechanisms of the odour perception of aroma compounds, odour detection thresholds, and issues relating to the effects of the matrix. It also considers the factors that have been found to cause differences in olfactory perceptions between panellists/judges, and covers some of the work that has been carried out in characterising perceptual interactions between compounds in wine. Gaps that exist in the current literature are highlighted. [ABSTRACT FROM AUTHOR]

This study investigated the relationship between bacterial counts and volatile organic compound (VOC) formation in 3.9% fat milk. The milk was stored at 7, 10, 13, 15 and 19 (±1 °C). Volatile compounds were measured using solid‐phase microextraction with gas chromatography. Enzyme activity was also monitored throughout the shelf life. Results show that volatile organic compound concentrations increased with higher bacterial counts (5.0–7.0 log10 cfu/mL). Bacterial counts correlated closely with acetaldehyde, butanone, ethanol, hexanal, acetone and fatty acid concentrations. Results indicate that protease and lipase activities increased and correlated closely with VOCs. Formation of VOCs was detectable when protease and lipase activities reached 1.2–1.3 U/mL and 0.32–0.350 meq/mL, respectively. These findings provide a basis for the monitoring of milk quality using chemical sensors that are sensitive to VOCs, particularly under conditions of thermal abuse. [ABSTRACT FROM AUTHOR]

Highlights • Rams have superior production performance than castrates. • Small sensory differences exist between meat from rams and castrates. • Consumers prefer castrate meat but do not dislike ram meat. • More intense flavour and off-flavours are found in meat from older lambs. Abstract Meat from ram lambs is often considered inferior to meat from castrated lambs, especially in older or heavier animals. This study aimed to determine if differences exist in the sensory quality and acceptability of meat from rams and castrates, slaughtered at mean ages of 196 or 385 days. Rams had higher average daily gain, feed conversion efficiency, total weight gain and lower carcass fatness than castrates. A triangle test (n = 81 consumers) showed a difference (P < 0.05) in the sensory quality of meat from rams vs castrates. A 9-point hedonic test involving 100 consumers showed that, although meat from both rams and castrates was 'liked', meat from castrates scored higher (P < 0.05) in Overall Liking, Flavour Liking and Tenderness Liking. Meat from castrates was also rated lower (P < 0.05) in Unpleasant Taste/Off-Flavour Intensity. Flavour Intensity and Unpleasant Taste/Off-Flavour Intensity increased (P < 0.05) with age at slaughter. This consumer study revealed that while meat from castrates was higher in Overall Liking, Flavour Liking and Tenderness Liking and lower in Unpleasant Taste/Off-Flavour Intensity than meat from rams, both meats were 'liked' by consumers. [ABSTRACT FROM AUTHOR]

The microorganisms of spoiled industrial-scale Sichuan paocai (ISSP) were isolated using six types of media, and 16S rRNA and 26S rRNA gene sequence analyses were used to identify the isolates. Meanwhile, the microbial composition was investigated using a culture-independent method through 16S rRNA and ITS sequencing on an Illumina MiSeq platform. The results obtained by these two methods were compared. Furthermore, characteristics of the isolated microorganisms responsible for ISSP spoilage were studied. Sixty-two strains belonging to twenty-three species, including three ammonia-producing genera, two gas-producing genera, two pectinase-producing genera, two cellulase-producing genera, three film-producing genera and one slime-producing genus, were isolated. Lactobacillus , Bacillus , Debaryomyces and Kazachstania were the dominant genera as confirmed through both culture-dependent and culture-independent methods. Bacillus , Paenibacillus , Pichia and Debaryomyces could be the main microorganisms responsible for ISSP spoilage. Bac. licheniformis was closely correlated with the off-flavour of ISSP. Pae. peoriae , Bac. stratosphericus , Bac. toyonensis and Bac. cereus were responsible for tissue softening, and Bac. subtilis , Bac. methylotrophicus , Pic. membranifaciens and Deb. hansenii caused film formation. [ABSTRACT FROM AUTHOR]

(Z)-4-undecenal (Z4-11Al) is the volatile pheromone produced by females of the vinegar fly Drosophila melanogaster. Female flies emit Z4-11Al for species-specific communication and mate-finding. A sensory panel finds that synthetic Z4-11Al has a characteristic flavour, which can be perceived even at the small amounts produced by a single female fly. Since only females produce Z4-11Al, and not males, we can reliably distinguish between single D. melanogaster males and females, according to their scent. Females release Z4-11Al at 2.4 ng/h and we readily sense 1 ng synthetic Z4-11Al in a glass of wine (0.03 nmol/L), while a tenfold concentration is perceived as a loud off-flavour. This corroborates the observation that a glass of wine is spoilt by a single D. melanogaster fly falling into it, which we here show is caused by Z4-11Al. The biological role of Z4-11Al or structurally related aldehydes in humans and the basis for this semiochemical convergence remains yet unclear. [ABSTRACT FROM AUTHOR]

Abstract: The bioconcentration of waterborne geosmin in rainbow trout, Oncorhynchus mykiss (Waldbaum) was assessed. Fifty rainbow trout with a mean (SD) weight of 226.6 (29.0) g and lipid content of 6.2 (0.6) % (w/w) were exposed to geosmin in static water for 0, 2, 4, 6, 8, 12, 24, 36, 48 and 120 hr, with one tank containing five fish for each exposure period. Geosmin concentrations were measured in fish tissue and water samples collected over time. With time the geosmin concentration in the fish increased and decreased in the water. However, the total absolute amount of geosmin in the system declined over time which could be explained by induction of biotransformation. This is in accordance with the decreasing lipid normalized geosmin levels in the liver compared with the liver‐free carcass. Geosmin distribution within rainbow trout clearly is not exclusively governed by the lipid content of tissues. In vivo geosmin bioconcentration in rainbow trout is slower and the body burden reached is lower than the generally accepted theoretical model predicts. [ABSTRACT FROM AUTHOR]

The identification of compounds producing a characteristic off-flavour in fresh beef meat obtained from different locations is essential to avoid consumer rejection. The volatile compounds of fresh beef samples were extracted by solid phase micro extraction (SPME) and their odour was evaluated by using olfactometry analysis (GC-O). The compound responsible for the characteristic off-flavour was identified by using GC-MS and quantified in different beef samples obtained from different locations. The sniffing analysis revealed eight odour active zones being four of them identified as 2,3-butanedione, allyl methyl sulfide, 1-(methylthio)propane and 1-(methylthio)-1-propene (Z). The most potent odorant was 1-(methylthio)propane described as garlic, cabbage, oxidized iron, solvent and rancid odour. All panellists attributed the characteristic off-flavour detected in fresh beef to the odour of 1-(methylthio)propane. A chromatographic method was validated to quantify 1-(methylthio)propane in fresh beef. Several beef samples were characterized by this off-flavour although its origin was not elucidated. [ABSTRACT FROM AUTHOR]

The aim was to study lipase, lipoxygenase (LOX) and peroxygenase (POX) activities in oat and faba bean samples to be able to evaluate their potential in formation of lipid-derived off-flavours. Lipase and LOX activities were measured by spectroscopy, and POX activities via the formation of epoxides. An ultra-high performance liquid chromatography method was developed to study the formation of fatty acid epoxides. The epoxides of esters were measured by gas chromatography. Mass spectroscopy was used to verify the identity of the epoxides. Both oat and faba bean possessed high lipase activities. In faba bean, LOX catalysed the formation of hydroperoxides, whose break-down products are the likely cause of off-flavours. Since oat had low LOX activity, autoxidation is needed to initiate lipid oxidation. Oat had high POX activity, which is able to convert hydroperoxides to epoxy and hydroxy fatty acids that could contribute significantly to off-flavours. POX activity in the faba bean was low. Thus, in faba bean volatile lipid oxidation products could rapidly be formed by LOX, whereas in oat reactions are slower due to the need of autoxidation prior to further reactions. [ABSTRACT FROM AUTHOR]

Yeast extracts is a kind of food ingredient for enhancing flavor, but some yeast extract samples had yeasty odour (off-flavour). The aim of this study was to detect key aroma compounds leading to the yeasty odour. Volatile compounds of 3 yeast extracts (with yeasty odour), FA and FB, LC were extracted by solid phase micro-extraction (SPME) and solvent assisted flavour evaporation (SAFE) respectively, and analysed by gas chromatography-olfactrometry-mass spectrometry (GC-O-MS) and aroma extract dilution analysis (AEDA) techniques. Thirty aroma-active compounds were detected, among them 4-methylphenol, 3-methylpyridine, 3-methylbutanoic acid, propanoic acid with high FD factors (FD = 125, 125, 625, 125, ≥25), were identified as the key off-flavours responsible for yeasty and their accurate quantification were done by external standard method in SIM mode. Calculation of the OAVs revealed 3-methylbutanoic acid, 3-methylpyridine, 4-methylphenol as the key odourants in the extract. For the verification of analyzed off-flavours, sensory evaluations of aroma model were conducted by eight panelists, and the result showed that aroma recombinate had the yeasty odour profile similar with the original yeast extracts. The methods were successful for the detection of off-flavors in yeast extract and the four off-compounds analyzed were mainly responsible for the yeasty flavour. [ABSTRACT FROM AUTHOR]

This study investigated relationships between the volatile profile and balanced flavour of high sensory quality ewe's raw milk commercial cheeses, and those relations between certain volatile compounds and off-flavours in defective cheeses. Commercial cheeses were selected in the routine sensory quality control from 27 farmhouses. High sensory quality cheeses showed a particular desirable balanced flavour and volatile profile. However, an imbalanced composition of volatile compounds was found in off-flavour cheeses. Rancid off-flavour was mainly related to an excessive concentration of n-butanoic and n-hexanoic acids, and their corresponding ethyl esters, generated by strong lipolysis during ripening. Animal off-flavour was associated with the generation of 3-methylbutan-1-ol, 2-phenylethanol and 4-methylphenol originated by amino acid catabolism after intense proteolysis. Finally, acid off-flavour was related to an excessive abundance of acetic acid generated mainly by strong glycolysis at early stages of ripening. [ABSTRACT FROM AUTHOR]

Defatting soybean by sophisticated oil extraction method utilising supercritical CO 2 resulted in a significant decrease in the residual phospholipids (PLs) compared with soymeal obtained by conventional cold percolation method utilising hexane as the extraction solvent. Interestingly, the levels of residual PLs showed a proportionate relationship with thiobarbituric acid (TBA) number, an indicator of lipid peroxidation responsible for off-flavour generation. Furthermore, two oleosins (18 and 24 kDa) were isolated from the oil bodies extracted from soybean seeds and positively characterised for phospholipase A 2 (PLA 2 ) activity, suggesting their plausible involvement in off-flavour generation in soymeal. The treatment of soybean seeds, before oil extraction, with different concentrations of biotic elicitors such as chitosan and jasmonic acid also significantly reduced the levels of residual PLs as well as the TBA number. The biotic elicitor treatment could thus prove to be an important strategy for the reduction of off-flavour in protein-rich soymeal. [ABSTRACT FROM AUTHOR]

Characteristic off-flavours may occur in uncastrated male pigs depending on the accumulation of androstenone and skatole. Feasible processing of strongly tainted carcasses is challenging but gains in importance due to the European ban on piglet castration in 2018. This paper investigates consumers' acceptability of two sausage types: (a) emulsion-type (BOILED) and (b) smoked raw-fermented (FERM). Liking (9 point scales) and flavour perception (check-all-that-apply with both, typical and negatively connoted sensory terms) were evaluated by 120 consumers (within-subject design). Proportion of tainted boar meat (0, 50, 100%) affected overall liking of BOILED, F (2, 238) = 23.22, P < .001, but not of FERM sausages, F (2, 238) = 0.89, P = .414. Consumers described the flavour of BOILED-100 as strong and sweaty. In conclusion, FERM products seem promising for processing of tainted carcasses whereas formulations must be optimized for BOILED in order to eliminate perceptible off-flavours. Boar taint rejection thresholds may be higher for processed than those suggested for unprocessed meat cuts. [ABSTRACT FROM AUTHOR]

Sales of bottled drinking water have shown a large growth during the last two decades due to the general belief that this kind of water is healthier, its flavour is better and its consumption risk is lower than that of tap water. Due to the previous points, consumers are more demanding with bottled mineral water, especially when dealing with its organoleptic properties, like taste and odour. This work studies the compounds that can generate obnoxious smells, and that consumers have described like swampy, rotten eggs, sulphurous, cooked vegetable or cabbage. Closed loop stripping analysis (CLSA) has been used as a pre-concentration method for the analysis of off-flavour compounds in water followed by identification and quantification by means of GC-MS. Several bottled water with the aforementioned smells showed the presence of volatile dimethyl selenides and dimethyl sulphides, whose concentrations ranged, respectively, from 4 to 20 ng/L and from 1 to 63 ng/L. The low odour threshold concentrations (OTCs) of both organic selenide and sulphide derivatives prove that several objectionable odours in bottled waters arise from them. Microbial loads inherent to water sources, along with some critical conditions in water processing, could contribute to the formation of these compounds. There are few studies about volatile organic compounds in bottled drinking water and, at the best of our knowledge, this is the first study reporting the presence of dimethyl selenides and dimethyl sulphides causing odour problems in bottled waters. [ABSTRACT FROM AUTHOR]

One of the most common taints in foods is a musty or earthy odour, which is commonly associated with the activity of microorganisms. Liquid foods, particularly wine and water, can be affected by this defect due to the presence of certain aromatic organic compounds at very low concentrations (ng/L) consistent with human threshold perception levels. The volatile compounds responsible for a mouldy off-aroma include approximately 20 compounds, namely, haloanisoles, geosmin, 2-methylisoborneol, several alkyl-methoxypyrazines, 1-octen-3-ol, 1-octen-3-one, trans-octenol, 3-octanone, fenchol and fenchone. Methods for determining these very low concentrations of odour compounds must be extremely sensitive and selective with efficient preconcentration treatments. A number of extraction techniques based on LLME (liquid–liquid microextraction), SPME (solid-phase microextraction) or SBSE (stir-bar sorptive extraction) can be applied and should be selected on a case-by-case basis. Moreover, recent developments in GC instrumentation coupled to different detection systems can effectively increase the selectivity and sensitivity of the analysis of target compounds. [ABSTRACT FROM AUTHOR]

Cork shows an active role in the sorption of volatile phenols from wine. The sorption properties of 4-ethylphenol and 4-ethylguaiacol phenols in hydro-alcoholic medium placed in contact with suberin extracted from cork were especially investigated. To that purpose, suberin was immersed in model wine solutions containing several concentrations of each phenol and the amount of the compound remaining in the liquid phase was determined by SPME–GC–MS. Sorption isotherms of 4-ethylguaiacol and 4-ethylphenol by suberin followed the Henry’s model. The solid/liquid partition coefficients ( K SL ) between the suberin and the model wine were also determined for several other volatile phenols. Suberin displayed rather high sorption capacity, which was positively correlated to the hydrophobicity of the volatile. Finally, the capacity of suberin to decrease the concentration of 4-ethylphenol and 4-ethylguaiacol was also tested in real wines affected by a Brettanomyces character. It also lead to a significant reduction of their concentration in wine. [ABSTRACT FROM AUTHOR]

The unpleasant odor of an off-flavor is mostly caused by only one or, sometimes, several volatile compounds with very low odor threshold values giving the typical unpleasant odor taint of the spoiled food product. 2-Aminoacetophenone is an aroma compound which causes the untypical aging off-flavor in Vitis vinifera white wines. Ultrasound assisted headspace solid phase microextraction ( UA-HS-SPME) and direct immersion solid phase microextraction ( DI-SPME) coupled with gas chromatography-mass spectrometry ( GC-MS) were tested and optimized for determination of 2-aminoacetophenone in Riesling wines fermented by different yeast strains. [ABSTRACT FROM AUTHOR]

The present study was aimed at determining the effect of gamma irradiation on off-flavour generation in four varieties of soybean with different seed coat colour. A significant enhancement in the level of anthocyanins in dark coloured varieties at all doses was observed. The isoflavones increased significantly at 0.25 kGy irradiation in all four varieties, while tocopherols were enhanced significantly only in dark varieties. The off-flavour determining parameters viz. Lipoxygenase activity, thiobarbituric acid number and carbonyl value decreased significantly in dark coloured varieties. Low doses of gamma irradiation, thus, seems to be a potential method for enhancing consumer acceptability of soybean. [ABSTRACT FROM AUTHOR]

Flavonoids, which are ubiquitously present in the plant kingdom, preserve food and beverages at the parts per million level with minor perturbation of sensory impressions. Additionally, they are safe and possibly contribute positive health effects. Flavonoids should be further exploited for the protection of food and beverages against light-induced quality deterioration through: (1) direct absorption of photons as inner filters protecting sensitive food components; (2) deactivation of (triplet-)excited states of sensitisers like chlorophyll and riboflavin; (3) quenching of singlet oxygen from type II photosensitisation; and (iv) scavenging of radicals formed as reaction intermediates in type I photosensitisation. For absorption of light, combinations of flavonoids, as found in natural co-pigmentation, facilitate dissipation of photon energy to heat thus averting photodegradation. For protection against singlet oxygen and triplet sensitisers, chemical quenching gradually decreases efficiency hence the pathway to physical quenching should be optimised through product formulation. The feasibility of these protection strategies is further supported by kinetic data that are becoming available, allowing for calculation of threshold levels of flavonoids to prevent beer and dairy products from going off. On the other hand, increasing understanding of the interplay between light and matrix physicochemistry, for example the effect of aprotic microenvironments on phototautomerisation of compounds like quercetin, opens up for engineering better light-to-heat converting channels in processed food to eventually prevent quality loss. © 2014 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

We investigated the influence of the level of fresh alfalfa supplementation on fat skatole and indole concentration and chop sensory attributes in grazing lambs. Four groups of nine male Romane lambs grazing a cocksfoot pasture were supplemented with various levels of alfalfa for at least 60 days before slaughter. Perirenal fat skatole concentration was higher for lambs that consumed alfalfa than for those that consumed only cocksfoot. The intensity of ‘animal’ odour in the lean part of the chop and of ‘animal’ flavour in both the lean and fat parts of the chop, evaluated by a trained sensory panel, increased from the lowest level of alfalfa supplementation onwards and did not increase further with increasing levels of alfalfa supplementation. The outcome of this study therefore suggests that these sensory attributes may reach a plateau when perirenal fat skatole concentration is in the range 0.16–0.24 μg/g of liquid fat. [ABSTRACT FROM AUTHOR]

Vacuum technology was applied for the first time at industrial scale to the mechanical extraction processes of virgin olive oil (VOO). The study was carried out using an industrial plant with a working capacity of 4 tons of olives. The use of high vacuum conditions during the malaxation process induced an intense mass transfer into the olive paste that improved the coalescence phenomena of oil droplets with a significant increase in oil extractability for four different cultivars (Arbequina, Arbosana, Koroneiki and Picual). The evaluation of the quality characteristics of the Picual VOO showed an enhancement in the hydrophilic phenol fraction mainly related to the oleacein content. The low temperature set during the vacuum treatment (16 ± 1 °C for 30 min of malaxation) limited the stripping process of the main aldehydes, alcohols and esters. In contrast, other negative volatile compounds related to off-flavoured VOO (ethanol, 3-methyl-1-butanol, ethyl acetate and acetic acid) were significantly reduced. • High vacuum technology applied to VOO extraction industrial plant. • Vacuum system increases the oil extractability of four cultivars. • Picual VOO improves their hydrophilic phenol content and antioxidant activity. • Low operative temperature limits the stripping phenomena of Picual volatile compounds. • Vacuum treatment reduces negative volatile compounds related to Picual VOO off-flavoured. [ABSTRACT FROM AUTHOR]

Exposure of milk to light leads to photooxidation and the development of off-flavours. To follow these reactions, semi-skimmed (1.5% fat) and whole (3.8% fat) extended shelf life (ESL) bovine milk samples were exposed to fluorescent light for up to 20 h at room temperature, and the volatiles in the samples' headspace were measured in real time using proton-transfer-reaction mass spectrometry (PTR-MS). Compounds tentatively identified as methanethiol, acetone/propanal, pentanal/octanal/nonanal/1-octen-3-ol, hexanal, diacetyl, dimethyl disulphide, heptanal and benzaldehyde displayed dynamic release profiles relating to the changes occurring in milk upon exposure to light. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Abstract: This study investigated whether the positive effects of ageing on tenderness of meat from culled dairy cows can be facilitated by CaCl2. Injections of 250mM CaCl2 solution (10% wt/wt) were performed on Longissimus dorsi samples from 32 7-yrs old cows. Samples were vacuum packaged and aged for 0, 1, 3, 5 and 7days. Ageing alone produced lighter and less red meat with lower shear force, higher myofibrillar fragmentation and tenderness scores but also elevated lipid oxidation. For most traits investigated, CaCl2-injected meat exhibited similar ageing effects, but drip loss increased with age. The CaCl2-injected meat had a lower shear force and myofibrillar fragmentation increased more rapidly, but drip loss, off-flavour scores, colour stability and oxidative stability were inferior to untreated meat. Overall, it was found possible to accelerate tenderisation of such meat with CaCl2, but only at the cost of adverse effects in some other quality traits. [Copyright &y& Elsevier]

Highlights: [•] SPME conditions on quantitative analysis of off-flavors in citral emulsion were first studied. [•] 65μm PDMS/DVB was the most suitable fiber for all the target citral degradation compounds. [•] SPME procedure was suitable for the analysis of the degraded volatile products in citral emulsion. [ABSTRACT FROM AUTHOR]

Aims Dekkera bruxellensis and Pichia guilliermondii are contaminating yeasts in wine due to the production of phenolic aromas. Although the degradation pathway of cinnamic acids, precursors of these phenolic compounds has been described in D. bruxellensis, no such pathway has been described in P. guilliermondii. Methods and Results A molecular and physiological characterization of 14 D. bruxellensis and 15 P. guilliermondii phenol-producing strains was carried out. Both p-coumarate decarboxylase ( CD) and vinyl reductase ( VR) activities, responsible for the production of volatile phenols, were quantified and the production of 4-vinylphenol and 4-ethylphenol were measured. All D. bruxellensis and some P. guilliermondii strains showed the two enzymatic activities, whilst 11 of the 15 strains of this latter species showed only CD activity and did not produce 4- EP in the assay conditions. Furthermore, PCR products obtained with degenerated primers showed a low homology with the sequence of the gene for a phenyl acrylic acid decarboxylase activity described in Saccharomyces cerevisiae. Conclusions D. bruxellensis and P. guilliermondii may share a similar metabolic pathway for the degradation of cinnamic acids. Significance and Impact of the Study This is the first work that analyses the CD and VR activities in P. guilliermondii, and the results suggest that within this species, there are differences in the metabolization of cinnamic acids. [ABSTRACT FROM AUTHOR]

The effect of temperature on the production of aromatic compounds using Heisei Miyazaki yeast MF062 was compared between 10 industrial yeasts. All yeasts tested produced characteristic patterns of alcohols and esters in fermentation tests with rice- koji at 20, 28 and 38°C. The concentration and composition in mature moromi with rice- koji at 20, 28 and 38°C were almost the same as those with barley- koji. Therefore, it was suggested that fermentation temperature is an important factor in the production of aromatic compounds. MF062 produced almost the same concentration of β-phenethyl alcohol at both 38 and 28°C. The concentration was higher than that generated by the other 10 yeasts. MF062 produced higher concentrations of i-butyl alcohol than the other yeasts at higher fermentation temperatures. Moreover, compared with the other yeasts, MF062 produced a lower concentration of acetate, which can give an off-flavour in excess concentrations in shochu. The production of acetoin was divided into two groups - a high producing group and a low producing group - at all temperatures. MF062 belonged to the latter group and showed preferred characteristics in the production of shochu, resulting in a high concentration of preferred aromatic compounds and a low concentration of compounds that impart an off-flavour. Copyright © 2013 The Institute of Brewing & Distilling [ABSTRACT FROM AUTHOR]

Abstract: Off-flavours develop naturally in butter and the process is accelerated by heat. An acoustic wave sensor was used to detect the aroma compounds evolved from heated butter and the results have shown that registered marked changes were coincident to odour changes detected by sensory analysis. The flavour compounds have also been analysed by GC/MS for identification. The response of the sensor was fully characterized in terms of the sensitivity to each of the identified compounds, and sensitivities of the system SPME/sensor were compared with the sensitivities of the system SPME/GC/MS. It was found that the sensor analytical system was more sensitive to methylketones than to fatty acids. The SPME/GC/MS system also showed the highest sensitivity to 2-heptanone, followed by 2-nonanone, but third place was occupied by undecanone and butanoic acid, to which the sensor showed moderate sensitivity. 2-heptanone was found to be an appropriate model compound to follow odour changes till the 500h, and the lower sensitivity of the sensor to butanoic acid showed to be a positive characteristic, as saturation was prevented, and other more subtle changes in the flavour could be perceived. [Copyright &y& Elsevier]

ABSTRACT Halogenated phenols and cresols belong to a group of volatiles consistently reported as off-flavour compounds. For example, 2-iodophenol and 2-iodo-4-methylphenol with their typical medicinal smell were found to negatively affect bottled mineral water. Even though these compounds are widespread in nature no comprehensive information about their chemo-analytical as well as odour properties is available. Therefore, the objective of this study were (1) to provide systematic chemo-analytical data on these substances, such as mass spectral data and retention parameters in gas chromatographic analysis, and (2) to determine, on a direct comparative basis, the sensory properties of eight mono-halogenated phenols, four di-halogenated phenols and four halogenated cresols. Evaluations focused on the determination of odour quality and odour threshold concentration in air and water. With regard to the relationship between substitution pattern and odour character, the location of an iodine atom in the ortho-position was demonstrated to obviously be an important prerequisite for medicinal, plaster-like or ink-like smell. Faecal or horse stable-like odour notes were predominantly related to compounds being substituted either by halogen moieties or by a methyl group in the para-position. The 2-halogenated 4-methylphenols were found to be the odorants with the lowest odour threshold concentrations of all the compounds investigated in this study, and that, generally, compounds with ortho-halogenation exhibited exceptionally low odour threshold concentrations. Copyright © 2012 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Abstract: The ability of cellulose acetate, cellulose acetate propionate (CAP), cellulose acetate butyrate and cellulose propionate (CP) fibres to reduce 4-ethylphenol and 4-ethylguaiacol, causing the off-flavour named “Brett character”, was studied. CAP and CP performed best in a preliminary comparative test. The former was chosen because of its more favourable FDA classification for food contact substances. CAP effectiveness was studied in relation to the reduction in volatile phenols with doses of up to 20g/l and wine contact times of up to 60min. Using 4g/l, reduction of both phenols was, on average, 31–32% in defective red wines. Wine treatment affected neither colour nor total proanthocyanidins and catechins, and wines were judged to be better than the corresponding spoiled controls. CAP fibre can be regenerated by washing with ethanol or aqueous solution (pH 12), without notable changes in depletion efficiency. The technological characteristics of CAP and, to a lesser extent, CP offer interesting prospects for producing filtration beds, pads and membranes for the treatment of wines and beverages affected by “Brett character”. [Copyright &y& Elsevier]

Abstract: Geosmin and 2-methylisoborneol (MIB) have been associated with off-flavour problems in fish and seafood products, generating a strong negative impact for aquaculture industries. Although most of the producers of geosmin and MIB have been identified as Streptomyces species or cyanobacteria, Streptomyces spp. are thought to be responsible for the synthesis of these compounds in indoor recirculating aquaculture systems (RAS). The detection of genes involved in the synthesis of geosmin and MIB can be a relevant indicator of the beginning of off-flavour events in RAS. Here, we report a real-time polymerase chain reaction (qPCR) protocol targeting geoA sequences that encode a germacradienol synthase involved in geosmin synthesis. New geoA-related sequences were retrieved from eleven geosmin-producing Actinomycete strains, among them two Streptomyces strains isolated from two RAS. Combined with geoA-related sequences available in gene databases, we designed primers and standards suitable for qPCR assays targeting mainly Streptomyces geoA. Using our qPCR protocol, we succeeded in measuring the level of geoA copies in sand filter and biofilters in two RAS. This study is the first to apply qPCR assays to detect and quantify the geosmin synthesis gene (geoA) in RAS. Quantification of geoA in RAS could permit the monitoring of the level of geosmin producers prior to the occurrence of geosmin production. This information will be most valuable for fish producers to manage further development of off-flavour events. [Copyright &y& Elsevier]

Abstract: Lupin protein extracts (LPE) are prone to the emission of a beany off-flavour during storage, which confines its application in foods. Fermentation of LPE using several lactic acid bacteria was conducted to reduce off-flavour formation in stored samples. The aroma profile of untreated LPE was compared to those of fermented protein extracts (LPEF). Hexanal and n-hexanol were used as indicator substances of progressing lipid oxidation. The most powerful odourants were evaluated by GC-olfactometry-flavour dilution analysis and identified according to their mass spectra, odour descriptions, and retention indices. Twenty two volatile substances with dilution factors equal to or higher than 100 were determined in both LPE and LPEF, amongst them n-pentanal, n-hexanal, 1-pyrroline, dimethyl trisulfide, 1-octen-3-one, 3-octen-2-one, 1-octen-3-ol, and β-damascenone. The aroma profile was significantly modified by the fermentation process and the off-flavours were reduced and/or masked by newly formed compounds. [Copyright &y& Elsevier]

Abstract: One of the contributing factors to generation of off-flavours in soy protein isolate (SPI) during storage is autoxidation of residual amounts of phospholipids present in SPI. Thus, removal of phospholipids from SPI is a likely first step to improve its flavour stability and enhanced utilisation of SPI in food products. We describe a β-cyclodextrin-based (βCD) process to remove protein-bound phospholipids and free fatty acids in SPI. Treating SPI solution (8%) with 10mM βCD alone at pH 8.0 decreased the phospholipid content of SPI by about 36%. A greater than 99% removal of phospholipids and free fatty acids was achieved by using a combination of treatments involving sonication of the SPI solution for 5min at 50°C followed by treatment with phospholipase A2 and βCD. SPI prepared by this method was white in colour. The results presented here offer a process for removing residual off-flavour causing phospholipids from soy protein. [Copyright &y& Elsevier]

Abstract: A new HPLC method using a diode array detector was developed and validated to quantify 4-ethylphenol, 4-vinylphenol, 4-ethylguaiacol, 4-vinylguaiacol and 4-ethylcatechol in cider. The procedure was linear up to 150mg/l for each of the five volatile phenols, precise (RSD<2.9%) and sensitive, with limits of detection between 0.03 and 0.10mg/l; moreover, it did not require any sample preparation. This method was applied to 11 phenolic off-flavour defective ciders. In these ciders, the main volatile phenol corresponded to 4-ethylcatechol. Moreover, the observed concentrations (maximum of 164mg/l) indicated, for the first time, that this compound is an important phenolic off -flavour marker in cider. Then, volatile phenols concentrations were determined for 47 French commercial ciders and showed mean quantities of 3.2 (4-EC), 0.8 (4-EP), 0.1 (4-EG), 0.2 (4-VP) and 0.3mg/l (4-VG). The majority of the tested commercial ciders presented low volatile phenol levels. [ABSTRACT FROM AUTHOR]

The 'earthy' and 'muddy' off-flavours in pond-reared fish are due to the presence of geosmin or 2-methylisoborneol in the flesh of the fish. Similar off-flavours have been reported in fish raised in recirculating aquaculture systems (RAS); however, little information is available regarding the cause of these off-flavours. Our hypothesis was that earthy and muddy off-flavour compounds, found previously in pond-raised fish, are also responsible for off-flavours in fish raised in RAS. In this preliminary study, we examined water, biofilms in RAS and fillets from cultured arctic charr known to have off-flavours and requiring depuration using instrumental [solid-phase microextraction procedure and gas chromatograph-mass spectrometry (GC-MS)] and human sensory analyses. Geosmin was present in the samples taken from the biofilter and on the side walls of the tanks. Two-methylisoborneol was only found in low levels in the samples. The GC-MS results indicated the presence of geosmin in the fillets (705 ng kg), but lower levels were found in the water (30.5 ng L). Sensory analyses also detected an earthy flavour (i.e., geosmin presence) in the fillets, and, therefore, it appears that geosmin is the main compound responsible for the off-flavour in RAS. Further studies are being performed to identify the microorganisms responsible for geosmin production in RAS. [ABSTRACT FROM AUTHOR]

Abstract: The effects of freeze-storage on human milk have been investigated with regard to sensory changes and modifications in the molecular composition of constituent odour-active volatiles. Sensory evaluation showed that fishy-metallic odour attributes are generated during storage, as are rancid-sweaty odour notes, which were described by panellists to be highly unpleasant. To monitor the dynamics of off-odour development in human milk, sensory evaluation in both orthonasal and retronasal mode was performed at defined time intervals of storage, with parallel evaluation of human milk samples that had been heated prior to freeze-storage. Heating was found to induce slight flavour changes, with generation of a predominantly egg-white-like note, but with no further generation of off-odour formation upon subsequent storage. This suggests that the formation of the off-odour in non-heated milk resulted from metabolic processes in the milk, although may also be due to the specific composition of human milk. In comparison, similar off-odour development was not observed in bovine milk. Molecular identification of the off-odour substances, most specifically free fatty acids and oxidation derivatives of polyunsaturated fatty acids, indicated both lipolytic and peroxidative processes of components of the native human milk. Finally, these results indicate that human milk is obviously a highly sensitive food material, specifically with regard to its characteristic fatty acid composition. [ABSTRACT FROM AUTHOR]

Abstract: A high concentration of indole has been linked to ‘plastic-like’ off-flavour in wines, predominantly in wines produced under sluggish fermentation conditions. The purpose of this study was to determine the ability of yeast and bacteria to form indole and whether tryptophan was required for indole accumulation during winemaking. Wine-associated yeast and bacteria species (Saccharomyces cerevisiae, Saccharomyces bayanus, Candida stellata, Hanseniaspora uvarum, Kluyveromyces thermoloterans, Oenococcus oeni, Lactobacillus lindneri, Pediococcus cerevisiae and Pediococcus parvulus) were screened for their potential to generate indole during alcoholic or malolactic fermentation. Tryptophan was required for the accumulation of indole in chemically defined medium, and all yeast and bacteria fermentations were able to accumulate indole. C. stellata showed the greatest potential for indole formation (1033μg/L) and among the bacteria, the highest concentration was generated by L. lindneri (370μg/L). Whether primary fermentation is the principle cause of indole formation remains to be determined. We hypothesise that during an efficient fermentation, indole is removed through catabolic metabolism, but, when a sluggish fermentation arises, non-Saccharomyces species might produce excess indole that is still present by end of fermentation. [Copyright &y& Elsevier]

Abstract: Breastfeeding is believed to impart major beneficial effects on babies, due to various human-specific components. Compatibility of family and profession, however, often necessitates the pumping of breast milk and its storage under diverse conditions, either in a refrigerator, freezer or for brief periods at room temperature. The present study investigates the formation of a characteristic fish-like and metallic off-odour during the conventional storage of human milk that does not develop during cow milk storage, and elucidates the molecular factors for these specific aroma changes. Odorants in fresh and stored human milk containing the specific fishy-metallic off-odour were characterized by means of gas chromatography–olfactometry and identified based on their mass spectrometric data and specific chromatographic and sensory characteristics. [Copyright &y& Elsevier]

Background and Aims: The aim of this study was to determine the cause of taints and off-flavours in a number of commercial wines and to develop methods for quantitative analysis of the compounds responsible. Methods and Results: Three compounds, 2-chloro-6-methylphenol (i.e. 6-chloro- ortho-cresol), 2,6-dichlorophenol and indole, were identified by gas chromatography (GC)/mass spectrometry (MS)/olfactometry as causes of taints or off-flavours in the wines. New methods for quantitative analysis of these three compounds, as well as some other chloro- and bromophenols were developed. The methods employed GC/MS and stable isotope dilution analysis, and confirmed the presence of 2-chloro-6-methylphenol, 2,6-dichlorophenol and indole in some wines at concentrations well above their odour and taste detection thresholds. Conclusions: 2-Chloro-6-methylphenol, 2,6-dichlorophenol and indole were confirmed as causes of taints and off-flavours in commercial wines. Significance of the Study: The development of new analytical methods will make it possible to determine whether chlorophenol (and perhaps also bromophenol) taint in wine is more widespread than previously recognised. Similarly, the simple, rapid and accurate method for quantifying indole in wine will allow large numbers of wine and ferment samples to be studied to determine those factors that can result in unacceptably high concentrations in commercial wines. [ABSTRACT FROM AUTHOR]

This study aimed to determine whether actinomycetes could contribute to the odours occurring in Lake Lotus, China. In total, 55 actinomycete strains were isolated from sediments in Lake Lotus and their odorous metabolites, geosmin and 2-methylisoborneol (2-MIB), were identified using HSPME-GC-MS. Results showed that 24, 23 and 34 strains produced geosmin and/or 2-MIB in Gause, TSB and M liquid media, respectively. Of odour-producing actinomycetes, most could produce geosmin and some produced both metabolites, while few of them produced only 2-MIB. Six isolates with high-level odour were selected for further investigation. Their biomass and odour-producing abilities were monitored in both the slants and liquid media. The results suggest that TSB was the most suitable medium for the growth of mycelium; Gause and M slant supported good production of spores, while M liquid medium was the most favourable for the production of both geosmin and 2-MIB. Those strains that produced geosmin only were less influenced than those that produced both geosmin and 2-MIB under shaking conditions. The results indicate that actinomycetes from sediments should be taken into consideration when off-flavours occur in water columns. According to the 16S rRNA sequences, six actinomycetes were classified in the Streptomyces. [ABSTRACT FROM AUTHOR]

Abstract: Different types of natural antioxidants (tocopherols – alone, in two different doses, or combined with ascorbic acid – and a rosemary extract) were employed in the production of corn flakes, to select the most effective ones for achieving low levels of volatile lipid oxidation products, related to off-flavours, after long-term storage. Samples were submitted to SPME/GC/MS and sensory analyses. Multivariate analysis elucidated the contribution of the volatile compounds to the sensory properties of corn flakes. Under the experimental conditions, tocopherols conferred better antioxidant activity than did rosemary extract, leading to low levels of off-flavour compounds, with a further improvement provided by the synergistic activity of ascorbic acid. This could be attributed to interfacial and phase partitioning phenomena involving antioxidants, depending on their lipo- or hydrophilicity, in heterogeneous food products. Acids, n-alkanols, lactones and some aldehydes appeared to have a considerable influence on the intensity of the off-flavours. [Copyright &y& Elsevier]

Abstract: Intensively farmed, market-size Murray cod (~600 g), were purged (transferred into a clean water system and starved) and sampled at three day intervals for a total of 18 days (D0, D3, D6, D9, D12, D15 and D18). Purged fish lost from 6% (D3) to 14% (D18) body weight, and the weight loss was highly correlated to the number of days of purging/starvation. Condition factor and Hepatosomatic Index decreased significantly (P <0.05) only after 18 days of purging compared to the control (D0). Fillet lipid content (%) did not vary during the trial. Eicosapentaenoic acid (EPA: 20:5 n−3) decreased and docosapentaenoic acid (DPA: 22:5 n−3) increased (P <0.05) during the trial, while docosahexaenoic acid (DHA: 22:6 n−3) did not show any significant variation. Purging contributed positively to the improvement of the volatile flavour compound composition, with a significant (P <0.05) reduction in total volatile aldehydes and an increase in total volatile hydrocarbons. Since no major differences were found between samples during the last stages of the purging process (D12, D15 and D 18), it is possible to conclude that, under these experimental conditions, 12 days is the minimum duration to obtain an improvement in the volatile compound profile of intensively farmed Murray cod whilst keeping body weight loss to a minimum. [Copyright &y& Elsevier]

Abstract: Volatile phenols are strong odorants produced by microbial activity and reported in several foods, but very scarce information is available on their presence in virgin olive oils (VOOs) and on their relation with VOO chemical and sensory quality. In the present paper, a factorial experimental design was applied for the development of a suitable solid-phase microextraction–gas chromatography/mass spectrometry (SPME–GC/MS) analytical method for the analysis of volatile phenols in olive oil. The memory effects demonstrated by SPME fibres required the optimization of desorption conditions to minimize experimental errors. A series of nine volatile phenols were identified and quantified for the first time in VOOs by analyzing samples with distinct off-flavours. Their limits of detection and quantification (μg/kg) were largely below the odour detection thresholds (ODTs) calculated in this study (mg/kg), confirming the capacity of the technique to assess the target compounds at early stages of the oil sensory alteration. The odour activity values (OAVs) of volatile phenols were calculated in VOOs facilitating a first assessment of their potential importance in the aroma of the product. [Copyright &y& Elsevier]

Abstract: A rapid immersion solid-phase microextraction (SPME) and gas chromatography (GC)–mass spectrometry (MS) method was developed to quantify 2-aminoacetophenone (2-AAP) in white wines. Thirteen white wines, including Pinot blanc, Pinot gris and Chardonnay were analyzed, and the concentrations of 2-AAP in these wines were ranging from <1 to 13ng/L. Sensory properties of 2-AAP in Pinot gris and Chardonnay were studied using flash profiling method. Aroma descriptors such as fruity, floral, buttery, oaky/toasty, painty, shoe insole, mothball and medicinal were developed for 2-AAP. Sensory evaluation demonstrated that when wines were spiked with increasing concentrations of 2-AAP, wine aromas (i.e. fruity and floral) were gradually lost while 2-AAP associated aromas (i.e. painty, mothball and medicinal) appeared. The 2-AAP associated aromas became prominent when the concentration of 2-AAP was increased to 0.5μg/L. [Copyright &y& Elsevier]

Lake Dianchi is the sixth largest freshwater lake in China. The pilot experimental area (6 km²) in Lake Dianchi is one of the most severely polluted areas in the lake with heavy cyanobacteria blooms. During June 2002 to May 2003, the algal composition and number, and odorous compounds were identified monthly and monitored in the area. Meanwhile, physicochemical parameters such as total phosphorus (TP), total nitrogen (TN), 5-day biochemical oxygen demand (BOD5), chemical oxygen demand (CODMn), dissolved oxygen (DO), pH, transparency, temperature and chlorophyll a (chla) were determined. Four odorous compounds: 2-methylisoborneol (MIB), geosmin, β-cyclocitral and β-ionone were found in the lake water. Both the concentration of particulate β-cyclocitral and that of β-ionone correlated significantly with the annual variation of Chla, biomass of total phytoplankton, cyanobacteria and Microcystis. The concentration of particulate MIB correlated significantly with the biomass of Oscillatoria, while the concentration of particulate geosmin correlated significantly with the biomass of Anabaena. Off-flavour in the pilot area was found to be caused by a combination of β-cyclocitral- and β-ionone-producing Microcystis, MIB-producing Oscillatoria and geosmin-producing Anabaena. β-ionone, MIB and geosmin contributed collectively to the odour intensity in the lake water. [ABSTRACT FROM AUTHOR]