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Bread aroma is an important parameter for bread quality and this review aims to provide an overview of aroma compounds identified in bread crumb and how these compounds are formed. More than 150 volatile compounds were identified in bread crumb and they mainly originate from the fermentative activity of yeast, from oxidation of flour lipids and to a lower extend from Maillard reactions. Of those volatile compounds, 45 compounds can be characterized as aroma compounds, as they most likely can be sensed when the bread is eaten due to high odor activity values and flavor dilution factors. The influence of ingredients and mixing conditions on bread aroma has only been scarcely investigated. The fermentation conditions; yeast level and strain as well as fermentation temperature and time were found to significantly influence the aroma of bread crumb. Yeast level and strain mainly influence formation of compounds directly related to the fermentative activity of yeast, while fermentation temperature and time also influence formation of compounds from oxidation of flour lipids.

The aim of this study was to characterize the flavor profiles of 14 commercial apple ciders from the United Kingdom and Scandinavian region. The flavor properties were established by sensory profiling and analysis of volatile and non-volatile components, including titratable acidity, pH, residual sugars and organic acids. A total of 72 volatile compounds were identified in the 14 apple ciders using dynamic headspace sampling (DHS) coupled to gas chromatography-mass spectrometry (GC/MS). The main volatile compounds found in apple ciders were esters and higher alcohols, followed by aldehydes and fatty acids. Sensory characterizations of the aroma and taste of apple ciders were carried out by a trained sensory panel using descriptive analysis with 23 sensory attributes. The attributes apple, cooked apple, yeasty, sweet and sour were the most predominant sensory descriptors used to describe the similarities and differences in the samples. Principal component analysis (PCA) showed that floral and fruity (fresh apple, banana and pear) odors were highly associated with sweet taste and opposed to the more complex aroma attributes (yeasty, lactic, chemical, mouldy, black pepper and earthy) and sour taste. Most of the UK apple ciders were characterized by these complex odors and taste notes sour, astringent and bitter, whereas ciders from the Scandinavian region had diverse sensory profiles. Partial least squares regression (PLS) based on the sensory and chemical data was able to cluster the ciders according to differences in production methods (oak-aged or spontaneous fermentation; controlled malolactic fermentation; industrial production with flavor modifications). Moreover, this study also suggested that ciders with marked levels of acetate esters were characterized by cooked/fresh apple, citrus and tropical fruit odors.

Geosmin and 2-methylisoborneol are the most recognized off-flavors in freshwater fish, but terpenes may also contribute off-flavor in fish. We identified six monoterpenes, 11 sesquiterpenes, and three terpene-related compounds in pangasius and tilapia from aquaculture farms in Bangladesh. The concentrations of most of the volatiles were below published odor thresholds, except for α-pinene, limonene, β-caryophyllene, α-humulene, and β-ionone in tilapia, and limonene and β-ionone in pangasius. To identify sources of the terpenes, terpene profiles of fish feed and phytoplankton in the ponds were analyzed. In feed and mustard cake (feed ingredient), five monoterpenes and two sesquiterpenes were identified, and five of these compounds were also detected in the fish. In phytoplankton, 11 monoterpenes were found and three also occurred in the fish. The higher number of terpenes common to both fish and feed, than to fish and phytoplankton, suggests that feed was a more abundant source of odor-active terpenes in the fish than phytoplankton.

Effect of water treatment on concentrations of the off-flavor geosmin was examined in a RAS facility for commercial production of pikeperch (Stizostedion lucioperca). Short-term (minutes) and long-term (days) variations in concentrations of geosmin were measured in grow-out tanks, at inlet and outlet of biofilters and at the denitrification unit. Geosmin in water of the grow-out tanks ranged typically from

The sensory quality of chocolate is widely determined by the qualitative and quantitative composition of volatile compounds resulting from microbial metabolism during fermentation, and Maillard reactions taking place during drying, roasting and conching. The influence of applying mixed starter cultures on the formation of flavour precursors, composition of volatile aroma compounds and sensory profile was investigated in cocoa inoculated with cultures encompassing a highly aromatic strain of Pichia kluyveri or a pectinolytic strain of Kluyveromyces marxianus, and compared to commercially fermented heap and tray cocoa. Although only minor differences in the concentration of free amino acids and reducing sugars was measured, identification and quantification by dynamic headspace gas chromatography–mass spectrometry (HS/GC–MS) revealed pronounced differences in the composition of volatiles in roasted cocoa liquors and finished chocolates. 19 of the 56 volatile compounds identified in the chocolates were found in significantly higher amounts in the tray fermented sample, whilst significantly higher amounts of 2-methoxyphenol was measured in the two inoculated chocolates. The P. kluyveri inoculated chocolate was characterized by a significantly higher concentration of phenylacetaldehyde and the K. marxianus inoculated chocolate by significantly higher amounts of benzyl alcohol, phenethyl alcohol, benzyl acetate and phenethyl acetate compared to a spontaneously fermented control. Sensory profiling described the heap and tray fermented chocolates as sweet with cocoa and caramel flavours, whilst the inoculated chocolates were characterized as fruity, acid and bitter with berry, yoghurt and balsamic flavours. The choice of fermentation technique had the greatest overall impact on the volatile aroma and sensory profile, but whilst the application of starter cultures did affect the volatile aroma profile, differences were too small to significantly change consumer perception of the chocolates as compared to a spontaneously fermented control.

Egg yolk stabilized butter sauces, such as hollandaise sauce, are classics in the French cuisine and adopted all over the world. They can be made using a number of different procedures. This study was done to determine how common butter sauce preparation methods influence perceptional parameters such as texture, mouthfeel and flavor. The goal was to evaluate the effects of the various preparation methods in order to gain control of the process and obtain the desired sauce properties. Five model sauces, prepared with the same amounts of ingredients, but with different procedures, were produced and analyzed. Sauce preparation methods differed regarding the amount of mechanical treatment, order of addition of ingredients, ingredient temperatures and states reached during production. The five model sauces were analyzed by particle size distribution, water and airiness measurements, microscopy, color measurement, descriptive sensory analysis and analysis of volatiles. Results demonstrated large differences between the explored types of hollandaise sauce, with texture and mouthfeel properties varying significantly with different preparation techniques. This study also included feedback from experienced chefs regarding their habits related to hollandaise sauce preparation.

Pangas Pangasianodon hypophthalmus and tilapia Oreochromis niloticus were culti- vated for 6 mo in earthen ponds in Bangladesh to examine occurrence of the off-flavour geosmin in water and fish and to test procedures for reduction of off-flavour. In the ponds (~1 m depth and area of 400 m 2 ), the average geosmin concentration was 3.9 ng l �1 (range 0.2 to 20 ng l �1 ). No effects of season or water treatment (sand filtration or probiotic microbes) were found. The content of geosmin in the fish was 21 ng kg �1 (range: 0.0 to 91 ng kg �1 ) for pangas and 17 ng kg �1 (range: 0.0 to 68 ng kg �1 ) for tilapia. Water treatment reduced the geosmin content by 56 to 74% in pan- gas, but no effect was found in tilapia. Likewise, depuration for ≥12 h in groundwater lowered the geosmin content in pangas (by 65 to 90%) but not in tilapia. Sensory analysis indicated a positive effect of both water treatment and depuration, and the fish were graded 'no or mild flavour' after such treatment, compared to 'strong off-flavour' in controls. Abundance analyses of known off- flavour producing microorganisms (streptomycete bacteria and cyanobacteria) showed a high density of streptomycetes (0.5 to 13% of the bacterial population), while cyanobacteria made up a maximum of 9.3% of the phytoplankton biomass or were absent. This first study on off-flavours in pangas and tilapia in Bangladeshi ponds indicates that geosmin was not a major off-flavour in the fish, but improvement of sensory quality by water treatment and depuration suggests that other, unidentified off-flavours were present in the fish.

Bread aroma is an important parameter for bread quality, and this review aims to provide an overview of aroma compounds identified in bread crumb and how these compounds are formed. More than 150 volatile compounds were identified in bread crumb, and they mainly originated from the fermentative activity of yeast, from oxidation of flour lipids, and to a lower extent from Maillard reactions. Of those volatile compounds, 45 compounds can be characterized as aroma compounds, because they most likely can be sensed when the bread is eaten because of their high odor activity values and flavor dilution factors. The influence of ingredients and mixing conditions on bread aroma has scarcely been investigated. The fermentation conditions (yeast level and strain as well as fermentation temperature and time) were found to significantly influence the aroma of bread crumb. Yeast level and strain mainly influence formation of compounds directly related to the fermentative activity of yeast, whereas fermentation...

Baker's yeast is used for bread fermentation throughout the world and it is very important for the bread quality. The scope of this work was to investigate how the aroma of wheat bread crumb is influenced by yeast fermentation by comparing the aroma formation of bread fermented by seven commercial baker's yeasts. Dough samples were fermented with equal number of yeast cells to equal height and then baked. The volatile components were extracted by dynamic headspace sampling and analyzed by gas chromatography mass spectrometry. The dough fermentation time varied significantly from 40 to 100 min. The fermentation compounds 2,3-butanedione and 1-propanol were found in significantly higher concentration in bread fermented with the four baker's yeasts having the shortest fermentation times. Furthermore, 3-methylbutanal, 2-methyl-1-propanol and ethyl acetate were found in significantly higher concentration in two of the yeasts. On the other hand phenylacetaldehyde and 2-phenylethanol were found in significantly higher concentration in bread fermented with two other yeasts. It can be concluded that use of the seven commercial baker's yeasts for bread fermentation resulted in significantly different bread aroma profiles.

Three types of cheese powders made from well-matured smear-ripened, hard, or blue cheese, were subjected to sensory profiling and analysis of volatiles, key aroma compounds, amino acids and organic acids. Blue cheese powders had high flavour intensities, especially of ‘fruity’ and ‘blue’ odour and flavour, which were related to a high content of methyl ketones and alcohols, esters and free fatty acids typically produced by Penicillium species. Smear cheese powders, characterised by ‘smear’ odour and flavour, were associated with flavour compounds derived from catabolism of sulphuric and branched-chain amino acids. Hard cheese powders described by ‘Goya’ odour and flavour as well as ‘umami’, ‘harmony’ and ‘kokumi’, had low or medium amounts of most compounds. The different characteristics of the three cheese powders can make them useful in different food applications as flavours or flavour enhancers.

Sliced saveloy samples were inoculated with monocultures of four potential spoilage bacteria and studied during a four week storage period. The objective was to investigate the resulting changes in the composition of Volatile Organic Compounds (VOCs) and the sensory quality of the product. Based on the sensory scores and the VOC composition Brochothrix thermosphacta, Chryseomonas luteola and Carnobacterium maltaromaticum were found to have a high spoilage potential in saveloy samples subjected to consumer simulated storage during the fourth week. Inoculation with Leuconostoc carnosum only resulted in a low level of spoilage. The sensory changes in the saveloy samples were modeled based on the VOC composition using Partial Least Squares Regression. The changes in the six sensory descriptors were closely related to the amount of diacetyl, acetoin, 2- and 3-methylbutanol, 2- and 3-methylbutanal and 2-methylpropanol found in the samples. These compounds are therefore potentially important for the shelf-life of sliced saveloy.

The consumers of today have an increasing interest in high quality bread with appealing aroma. The scope of this work is to investigate how aroma in wheat bread crumb is influenced by different fermentation conditions: amount of yeast (20, 40 and 60 g/kg flour) and fermentation temperature (5, 15 and 35 °C). Dough samples were fermented to equal height and baked, and the aroma compounds from the bread were extracted by dynamic headspace extraction and analyzed by gas chromatography–mass spectrometry. Quantification of the aroma compounds was performed by multiple headspace extraction. The most aroma active compounds identified were 3-methylbutanal, (E)-2-nonenal, 3-methyl-1-butanol, and 2,3-butanedione. Increasing the yeast concentration was found to increase formation of the majority of the compounds formed from the yeast metabolism, with 2,3-butanedione and phenylacetaldehyde as the most aroma active compounds. High fermentation temperature (15 and 35 °C) increased formation of many lipid oxidation compounds, with hexanal and heptanal having the highest odor activity values. Low fermentation temperature (5 °C) was found to increase formation of the three esters ethyl acetate, ethyl hexanoate, and ethyl octanoate, with ethyl hexanoate having the highest odor activity value. The odor activity values of the esters were generally low.

Quantification of 62 aroma compounds in three commercial semi-hard cheeses with different fat contents and maturity levels was pursued. Dynamic headspace sampling and gas chromatography–mass spectrometry (GC–MS) was applied after spiking each of the three cheeses with the aroma compounds, and PARAllel FACtor analysis was used to resolve co-eluting compounds. By the use of linear regression, half of the spiked aroma compounds exhibited similar slopes in the three cheeses whereas the volatilities of 15 other compounds were dependent on their hydrophilicity relative to the fat content of the cheese. For nine aroma compounds, satisfactory coefficients of determination were obtained in one or two of the cheeses only, and seven compounds could not be quantified at all.

Hexanal formation and pentanal formation were found to be early signs of quality deterioration of both a high lipid infant formula milk powder and a high protein infant formula milk powder with similar lactose and water content; these aldehydes were sensitive predictors for shelf-life at ambient conditions using short term storage at temperatures up to 55 °C. Higher temperature loads such as 70 °C were found to induce rapid lactose crystallisation entailing a rising water activity, higher levels of free radicals, rapid browning and formation of Strecker aldehydes from protein degradation, of which all were found to be unsuitable for shelf-life prediction. Advanced glycation end products were not detected during storage at 25 °C for up to 18 weeks and the rate of oxygen consumption for the reconstituted milk drink was not affected by storage of the infant formulas at 25 °C; neither can be recommended for shelf-life prediction.

Wort from the barley varieties (Hordeum vulgare) Pallas, Fero, and Archer grown on the same location were investigated for their influence on oxidative stability and volatile profile during wort processing. Barley varieties had a small influence on radical formation, thiol-removing capacity, and volatile profile. Wort boiling with and without hops had a large influence on these same parameters. Potentially antioxidative thiols were oxidized in sweet wort, but reduction of thiols using tris(2-carboxyethyl)phosphine hydrochloride revealed that Archer wort had a significantly larger content of total thiols than Pallas and Fero. Oxidized thiols resulted in gel proteins and longer filtration time for Archer wort. Our study shows that wort processing to a large extent will eliminate variations in volatile profile and thiol levels in wort which otherwise might arise from different barley varieties.

Author Summary: This study demonstrates the application of a novel variable selection method here employed for the prediction of sweet and sour taste of apple juice from Nuclear Magnetic Resonance (NMR) spectra. The method is called recursive weighted Partial Least Square (rPLS). It operates by iteratively re-weighting the spectral variables using the regression coefficients calculated by PLS. The only parameter to be estimated by the operator is the number of latent factors to be used in the model. This approach provides an easier model interpretation than a regular PLS model, since it converges towards a very limited number of variables and therefore the assignment effort is drastically reduced. These properties suggest a profitable use of the rPLS for the prediction of even more complex sensory features from different types of spectroscopic data.

Summary This paper studied the fast sensory Rate-All-That-Apply (RATA) method as a contributor to existing quality control (QC) in chocolate production by comparing it with the outcome of dynamic headspace sampling combined with gas chromatography–mass spectrometry (DHS-GC-MS). Seven different chocolates were evaluated by a semi-trained panel using RATA. RATA showed potential as a sensory evaluation tool which could be part of QC programmes in chocolate production as RATA was efficient to perform and captured important sensory deviations, herein addition of excess lecithin and prolonged roasting. However, product deviations caused by long conching were only detected by DHS-GC-MS. A more extreme conching process must occur before it can be perceived by humans. RATA and DHS-GC-MS should be used as complementary methods in detecting future important issues in chocolate production. DHS-GC-MS detects product deviation from chemical perspectives while sensory evaluation gives information on quality parameters from a perceivable perspective influencing consumer satisfaction.

Biotic interactions through volatile organic compounds (VOC) are frequent in nature. This investigation aimed to study the role of ITALIC! BacillusVOC for the beneficial effects on plants observed as improved growth and pathogen control. Four ITALIC! Bacillus amyloliquefacienssubsp. ITALIC! plantarumstrains were screened for VOC effects on ITALIC! Arabidopsis thalianaCol-0 seedlings and ITALIC! Brassicafungal phytopathogens. VOC from all four ITALIC! Bacillusstrains could promote growth of ITALIC! Arabidopsisplants resulting in increased shoot biomass but the effects were dependent on the growth medium. Dose response studies with UCMB5113 on MS agar with or without root exudates showed significant plant growth promotion even at low levels of bacteria. ITALIC! BacillusVOC antagonized growth of several fungal pathogens ITALIC! in vitro However, the plant growth promotion efficacy and fungal inhibition potency varied among the ITALIC! Bacillusstrains. VOC inhibition of several phytopathogens indicated efficient microbial antagonism supporting high rhizosphere competence of the ITALIC! Bacillusstrains. GC-MS analysis identified several VOC structures where the profiles differed depending on the growth medium. The ability of ITALIC! Bacillusstrains to produce both volatile and soluble compounds for plant growth promotion and disease biocontrol provides examples of rhizosphere microbes as an important ecosystem service with high potential to support sustainable crop production.

Marama bean ( Tylosema esculentum ) is an underutilised legume indigenous to the Kalahari Desert region of southern Africa. The bean has high lipid content and hence is a potential source for production of edible oil. The headspace volatile composition of freshly pressed marama bean oil was explored and the oil was further studied during 7 months of storage under different light and temperature conditions. The oxidative stability of the oil was examined by measuring peroxide value, vitamin E content and FT-IR spectra. Additionally, the headspace volatile composition of the oil was investigated during storage by use of dynamic headspace GC–MS. The results showed that marama oil is highly stable and has good natural antioxidant properties; enzymatic lipid oxidation does not take place in marama oil. Light has a greater effect on the lipid oxidation than has temperature, and hence marama oil should preferably be stored in darkness and rather at 25 °C than 35 °C. Under these conditions, the marama oil has a shelf life of at least 7 months.

Flavor production among 12 strains of Debaryomyces hansenii when grown on a simple cheese model mimicking a cheese surface was investigated by dynamic headspace sampling followed by gas chromatography-mass spectrometry. The present study confirmed that D. hansenii possess the ability to produce important cheese flavor compounds, primarily branched-chain aldehydes and alcohols, and thus important for the final cheese flavor. Quantification of representative aldehydes (2-Methylpropanal, 3-Methylbutanal) and alcohols (2-Methyl-1-propanol, 3-Methyl-1-butanol, and 3-Methyl-3-buten-1-ol) showed that the investigated D. hansenii strains varied significantly with respect to production of these flavor compounds. Contrary to the alcohols (2-Methyl-1-propanol, 3-Methyl-1-butanol, and 3-Methyl-3-buten-1-ol), the aldehydes (2-Methylpropanal, 3-Methylbutanal) were produced by the D. hansenii strains in concentrations higher than their sensory threshold values, and thus seemed more important than alcohols for cheese flavor. These results show that D. hansenii strains may have potential to be applied as cultures for increasing the nutty/malty flavor of cheese due to their production of aldehydes. However, due to large strain variations, production of flavor compounds has to be taken into consideration for selection of D. hansenii strains as starter cultures for cheese production.

The aroma composition, the microbial composition and the sensory profile were measured in sliced saveloy samples packed in modified atmosphere (MA). The main objective was to identify aroma compounds with potential as chemical markers to identify the sensory changes of saveloy. The 60 aroma compounds isolated from the saveloy samples by dynamic headspace extraction and measured by Gas Chromatography Mass Spectrometry (GC-MS) were used to model the sensory attributes sour&old odour and meaty odour using partial least squares regression (PLS). 2- and 3-methylbutanal, 2- and 3-methylbutanol, acetoin and diacetyl were found to have the highest impact on both sour&old odour and meaty odour of the samples. The results show that these four aroma compounds have high potential as chemical markers for the sensory shelf-life of sliced and MA-packed saveloy.

The combined effect of two cocoa fermentation methods – heap and tray – and different roasting and conching conditions on aroma compounds of dark chocolate were investigated. Dynamic headspace sampling/gas chromatography-mass spectrometry (GC-MS) was used to isolate and identify aroma volatiles. Odor-active volatiles were detected and identified by gas chromatography-olfactometry/GC-MS. Fermentation method, roasting and conching conditions influenced mostly the levels of aroma volatiles identified. Principal component analysis based on a reduced data set of 16 important odorants resulted in a total variance explained by two principal components of 81% accounting for fermentation method, roasting and conching conditions. The levels of most important odorants were generally higher at high roasting temperature (150C) but decreased significantly (P

A simple cheese model mimicking a cheese surface was developed for the detection of cheese flavour formation of yeasts. A total of 56 flavour compounds were detected by dynamic headspace sampling followed by gas chromatography–mass spectrometry analysis. Yarrowia lipolytica CBS 2075 primarily produced sulphides, furans and short-chain ketones; Saccharomyces cerevisiae D7 primarily produced esters and Debaryomyces hansenii D18335 primarily produced branched-chain aldehydes and alcohols. For several of the detected flavour compounds, an increase in production was observed upon exposure to dairy-relevant environmental stress conditions including high NaCl concentration and low temperature. The predominant yeasts on the cheese surface may be important for development of flavour, and thus the use of yeasts as ripening cultures has the potential to affect the flavour of cheese.

The purpose of this research was to investigate whether cutting direction and storage temperature could influence aroma formation and respiration rates in minimally processed lettuce. Lettuce was cut both longitudinally and transverse to the mid-rib and stored at 6 and 10 °C for 4 and 5 days. The experiment was performed in January and March 2008. Changes in respiration rate were analyzed during storage, and aroma analysis was carried out after 4 and 5 days of storage in January and March, respectively. Respiration rates increased with increasing storage temperatures. Transverse cuts to the rib were strongly related with volatiles of the lipoxygenase (LOX) pathway i.e. cis-3-hexenal, cis-3-hexenol and trans-2-hexenol, while longitudinal cutting enhanced formation of volatiles from other metabolic routes. Aroma formation was also influenced by storage temperature, where higher storage temperatures resulted in increases in α-longipinene, 2-methylbutanal and 3-methylbutanal. Our results demonstrate that cutting the lettuce transverse to the mid-rib caused more severe damage to the tissue than longitudinal cutting, based on aroma production of LOX volatiles.

The investigation was undertaken to establish a relationship between key odorants and perceived flavor attributes of dark chocolate as influenced by cocoa fermentation method, roasting and conching conditions, using multivariate data analysis in an attempt to use one variable to predict the other. Eight of the sixteen flavor attributes used by a trained sensory panel to describe and quantify the intensity of attributes in the samples were significantly different (p

Changes in the composition of volatile compounds during processing of cheese powders, made from Emmental and Danbo cheese were analysed by dynamic headspace gas chromatography-mass spectrometry. Samples comprised cheese, melted cheese slurry, the slurry heat treated using three different time and temperature combinations, and the spray-dried cheese powder. About 100 volatile compounds were identified. During melting of the cheese the level of some volatile compounds increased significantly; heat treatment mainly leads to a loss of compounds and spray drying leads to a substantial reduction of volatile compounds, with the exception of a range of aldehydes that increased. The final cheese powders could, however, be distinguished according to cheese type.

Extra hard cheese is commonly made with thermophilic starters using high temperatures to stimulate expulsion of whey. In this work, microflora, proteolysis and volatiles were investigated in an extra-hard cheese made with mesophilic DL-starter, produced using challenging cooking temperatures for the starter bacteria over several hours. Cheese from six commercially produced vats was investigated over 56 weeks. The number of starter bacteria decreased after three weeks of ripening. Casein breakdown was characterised by chymosin and plasmin activity on α s1 - and β-caseins, respectively. Peptide profiles showed accumulation of Lactococcus derived peptides from α s1 -CN f1–23, and the peptide β-CN 29–93 as a result of joint plasmin and chymosin activity and absence of highly proteolytic thermophilic Lactobacillus , commonly present in extra-hard cheese. The composition of amino acids depended mainly on starter during the first 26 weeks of ripening. The content of volatiles depended both on ripening time and the starter used.

The most straightforward method to analyze an obtained GC-MS dataset is to integrate those peaks that can be identified by their MS profile and to perform a Principal Component Analysis (PCA). This procedure has some important drawbacks, like baseline drifts being scarcely considered or the fact that integration boundaries are not always well defined (long tails, co-eluted peaks, etc.). To improve the methodology, and therefore, the chromatographic data analysis, this work proposes the modeling of the raw dataset by using PARAFAC2 algorithm in selected areas of the GC profile and using the obtained well-resolved chromatographic profiles to develop a further PCA model. With this working method, not only the problems arising from instrumental artifacts are overcome, but also the detection of new analytes is achieved as well as better understanding of the studied dataset is obtained. As a positive consequence of using the proposed working method human time and work are saved. To exemplify this methodology the aroma profile of 36 apples being ripened were studied. The benefits of the proposed methodology (PARAFAC2+PCA) are shown in a practitioner perspective, being able to extrapolate the conclusions obtained here to other hyphenated chromatographic datasets.

It has been suggested that mother’s milk has a more diverse flavor composition than infant formula milk as it reflects the maternal diet. This study aimed to identify volatile compounds in mother’s milk and infant formula milks to obtain more knowledge about these sources of early sensory exposure in infant feeding. Mother’s milk collected by ten lactating women, three times on three independent test days (n = 90), and 11 different formula milks were examined. Formulas included seven milk-based liquid formulas and four powder formulas (one milk-based and three hypoallergenic). Both mother’s milk and infant formulas were rich in lipid-derived volatile compounds including alcohols and carbonyl compounds. Formulas differed from mother’s milk as they contained more volatiles related to thermal treatment such as methional, 2-furfural, and sulfides. By comparison, mother’s milk revealed a higher variety of terpenes probably originating from the maternal diet. The number of identified volatiles in mother’s milk varied both within samples obtained from the same woman and significantly between women. The latter one suggests large variety in breast-fed infants’ exposure to volatiles. Qualitative differences existed for infant formulas. Powder forms revealed a greater number of compounds, predominantly secondary lipid oxidation products, and larger batch variations than liquid products. Extensively hydrolyzed formulas were significantly richer in volatile compounds associated with heat treatment of milk. These findings suggest that breast-fed infants are exposed to variations in volatile compounds in mother’s milk, while formula-fed infants are exposed to less diverse flavors when fed infant formula from the same brand.

Transfer of dietary flavour compounds into human milk is believed to constitute the infant's early flavour experiences. This study reports on the time-dependent transfer of flavour compounds from the mother's diet to her breast milk using a within-subject design. Eighteen lactating mothers completed three test days on which they provided a baseline milk sample prior to ingestion of capsules containing 100 mg d-carvone, l-menthol, 3-methylbutyl acetate and trans-anethole. Milk samples were collected 2, 4, 6 and 8 h post-ingestion and analysed by a dynamic headspace method and gas chromatography-mass spectroscopy. The recovery quantities were adjusted for variations in milk fat content. Concentration-time profiles for d-carvone and trans-anethole revealed a maximum around 2 h post-ingestion, whereas the profile for l-menthol showed a plateau pattern. The ester 3-methylbutyl acetate could not be detected in the milk, but a single determination showed traces (

Many essential oils and their terpene constituents display antimicrobial properties, which may affect rumen metabolism and influence milk production parameters. Many of these compounds also have distinct flavors and aromas that may make their way into the milk, altering its sensory properties. Essential oils from caraway (Carum carvi) seeds and oregano (Origanum vulgare) plants were included in dairy cow diets to study the effects on terpene composition and sensory properties of the produced milk, as well as feed consumption, production levels of milk, and methane emissions. Two levels of essential oils, 0.2 and 1.0 g of oil/kg of dry matter, were added to the feed of lactating cows for 24 d. No effects on feed consumption, milk production, and methane emissions were observed. The amount and composition of volatile terpenes were altered in the produced milk based on the terpene content of the essential oils used, with the total amount of terpenes increasing when essential oils were added to the diet. Sensory properties of the produced milk were altered as well, and milk samples from animals receiving essential oil treatment were perceived as having a fresher aroma and lower stored aroma and flavor. The levels of essential oils used in this study mimic realistic levels of essential oils in herbs from feed, but were too low to affect milk production and methane emissions, and their inclusion in the animal diet did not adversely affect milk flavor.

Colletotrichum acutatum is a major fungal pathogen of fruit crops, which causes severe yield losses in strawberry production. A potential key factor in plant–pathogen interactions is fungal sesquiterpenoids which have mycotoxic and phytotoxic activities. The first committed step in sesquiterpenoid biosynthesis is performed by sesquiterpene synthases (TPS). Only a few TPSs have been functionally characterized from filamentous fungi and none from the genus Colletotrichum. Despite being an important fungal pathogen to agriculture, it is poorly understood at the molecular and chemical levels. The terpenoid biochemistry in Coll. acutatum strain SA 0-1 was studied and one Coll. acutatum TPS (CaTPS) was successfully cloned and characterized in yeast. CaTPS catalyses the biosynthesis of multiple sesquiterpenoids. The two major products are β-caryophyllene and an unidentified sesquiterpenoid along with α-humulene as one of the minor sesquiterpenoid products. These products were also secreted by the fungus in strawberry fruit medium along with several other sesquiterpenoids indicating other TPSs are active during in vitro growth. β-Caryophyllene and α-humulene are known cytotoxic products important for ecological interactions and are produced by SA 0-1. Interestingly, a gene expression analysis using quantitative real-time PCR revealed a significant increase in expression of CaTPS during strawberry fruit infection, thus indicating that it could be involved in fruit infection. This is, we believe, the first characterization of TPS in Colletotrichum spp. and terpenoid profiles of Coll. acutatum, which could facilitate studies on the role of terpenoids in the ecology of Coll. acutatum.

A study was performed in order to evaluate the impact of a poly-lactic acid (PLA) package relative to a polyester packaging material on quality of semi-hard cheese during light exposure and storage in the dark and when applying oxygen scavengers to the cheese packages. Migration of volatile compounds from PLA into the cheese was minute and well below any critical levels. Development of secondary lipid oxidation products and loss of riboflavin primarily took place when both oxygen and light were present. As more oxygen was present in the PLA packages than in the reference packages due to a higher oxygen transmission rate of PLA, a higher degree of lipid oxidation was noted in cheeses packaged in PLA. The degree of lipid oxidation was reduced when applying oxygen scavengers but to a lesser extent than when the products were stored in the dark. Riboflavin was degraded to the same extent in the PLA and the reference-packaged cheeses. The results indicate that dark storage/use of non-transparent materials and reduction of the water vapour transmission rate are recommended when using the present PLA for packaging of semi-hard cheeses in order to protect the products against both lipid oxidation and moisture loss.

The objective of the present study was to investigate if an electronic nose, comprising six metal oxide sensors (MOS) could predict the sensory quality of porcine meat loaf, based on measuring the volatiles in either the raw materials or the meat loaf produced from those raw materials. A multivariate data analysis strategy involving analysis of variance partial least squares regression (APLSR) and principal component analysis (PCA) was used to determine causal and predictive relationships between the raw material and meat loaf samples, sensory analysis, electronic nose, and GC-MS measurements. The results showed that the six MOS sensors in the Danish odour sensor system (DOSS) could detect the raw materials that led to unacceptable products, as determined by sensory profiling and in-house sensory quality control (QC), and separate those raw materials from each other, based on the volatile composition, as determined by GC-MS. However, the electronic nose was unable to detect all the sensory unacceptable meat loaf samples themselves due to changes in the volatile composition after cooking. Analysis of the GC-MS compounds identified from raw materials and meat loaf samples indicate that two MOS sensors mainly responded to alcohols and to a lesser degree to aldehydes and alkanes, whereas two other sensors most likely responded to low molecular weight sulphur compounds. Thus, the results indicate that measuring volatiles with the MOS sensors in the DOSS system, on raw materials for processed meat products, may be a feasible strategy in sensory based quality control, and may also have potential in predicting the sensory quality of the end product.

The aim of the present study was to determine the contents of ascorbic acid in old Danish apple cultivars and in commercially available apple juices. Ascorbic acid was determined using the 2,6-dichloroindophenol method. The ascorbic acid content of the 71 analysed apple cultivars ranged from less than 1 to 27 mg/100 mL, with an average of 6.4 mg/100 mL. Preliminary results showed that upon pressing of apples the ascorbic acid was readily degraded. The levels of ascorbic acid found in the 18 commercial apple juices were negligible, the highest level was 2.6 mg/100 mL, but most were below 1 mg/100 mL. Hence to benefit from ascorbic acid in apples the fruits have to be eaten unprocessed.

When potatoes are boiled and then chill-stored they rapidly develop off-flavor. This is a result of lipoxygenase activity, and is a serious problem in food-service systems. Lipoxygenase activity may vary during winter-storage of potatoes. Raw potatoes of the variety 'Bintje' were therefore analyzed for lipoxygenase activity during winter storage. Furthermore, content of potential off-flavors and typical potato aroma compounds were determined in raw, boiled, and in boiled/chill-stored potatoes. Four months after harvest the lipoxygenase activity started to increase, both when linoleic and linolenic acid were used as substrates. Production of typical oxidation products (aldehydes) of these fatty acids that earlier have been shown to cause off-flavor in boiled/chill-stored potatoes did, however, decrease. It is therefore concluded that this was not due to changes in lipoxygenase activity.

Sliced Samso cheese, stored up to 3 weeks, exposed to light (1500 lx), packaged in 0% CO 2 (100% N 2 ), 20% CO 2 (80% N 2 ), or 100% CO 2 showed a significant decrease in yellowness ( b* ) and an increase in redness ( a* ). Cheese packaged in atmospheres containing 100% CO 2 and exposed to light was significantly darker ( L* ) than cheese exposed to 0% CO 2 , and the 100% CO 2 resulted in a drying-out of the cheeses. Descriptive sensory analysis revealed that light, gas composition, and storage time significantly affected taste and odour attributes of the semi-hard Samso cheese. Assessors characterised dark-stored cheeses packed in 20% CO 2 or 0% CO 2 as the most buttermilk-like. Cheeses packed in 100% CO 2 and exposed to light were described as rancid and as having a dry/crumbly texture. Dynamic headspace gas chromatography–mass spectrometry was used to identify volatile compounds. Significant light exposure effects during storage were noted for the following oxidation products: 1-Pentanol, 1-octanol, 2-ethyl-1-butanol, 2-butanol, 2-heptanol, 2-pentanol, 2-nonanol, benzaldehyde, 2-butanone, 2-nonanone, dimethyl trisulfide, and tetrahydrofuran. The gas composition had no impact on the formation of volatiles.

During storage for up to 52 weeks, under mildly accelerated conditions (22 °C, atmospheric air), potato flakes (1% lipid, dried to aw=0.4) were found to undergo oxidative changes as indicated by a slight decrease in headspace oxygen. The headspace concentration of hydrocarbons (ethane and pentane) steadily increased during storage, and the increase was reduced with added antioxidants. For a product without added antioxidants, three short-chain aldehydes increased slightly, but other secondary oxidation products did not change significantly (including thiobarbituric acid reactive substances). Long chain aldehydes (identified by GC–MS) were abundant in fresh products, but decreased during storage. The level of free radicals, as a marker of early events in oxidation and measured directly by electron spin resonance spectroscopy (ESR), increased significantly during the first 2 weeks of storage, followed by a marked decrease for the period of 2–22 weeks of storage to reach a steady state level. Throughout the period of storage, ESR spectrometry was able to rank products protected by natural antioxidant extracts according to increasing level of free radicals: Unprotected>Coffee>Green tea, Grape skin>Rosemary. Hydrocarbons evolved according to a similar pattern and it can be concluded that ESR spectrometry provides a method for detecting early stages of oxidation in this type of low fat dried products.

Malt is usually expected to be stable during 12 months of storage. However, in practice many brewers notice changes in malt aroma during storage. The oxidative stabilities of pilsner malt and roasted malt were evaluated during a 12 month storage at different temperatures (10 and 20 °C) and water activities (0.231 and 0.432). The radical content in malt kernels was measured by electron spin resonance spectroscopy and the volatile profile of the resulting sweet worts was measured by head-space analysis followed by GC-MS analysis. The storage of malt resulted in oxidative reactions and a large change of the volatile profile of the resulting worts. Roasted malt was much more unstable than pilsner malt, as illustrated by a higher initial radical intensity, larger radical decay during storage and a larger change in the volatile profile of the wort with increased amounts of lipid oxidation products. For both roasted malt and pilsner malt, good correlations were found between radical decay and changes in the volatile profile of the wort, where high temperature and high water activity resulted in the largest changes. During the 12 months of storage, the sugar extract of the wort made from the malts remained constant and was not affected by the chemical changes. This study suggests that chemical changes occurring in malts during less than 12 months of storage may potentially affect the aroma of beer, and that water activity and storage temperature should both be kept low in order to maintain a high malt quality. Copyright © 2014 The Institute of Brewing & Distilling

Boiled potato off-flavour is a cardboard-like note, that develops within hours when boiled potatoes are stored. Using a panel of four professional judges, it was verified that a clearly detectable off-flavour develops during the storage of boiled potatoes. Two different isolation methods (direct extraction and vacuum distillation/extraction) in combination with GC-MS and GC-sniffing were applied to the same freshly boiled and stored boiled potatoes. Eight compounds, (pentanal, hexanal, nonanal, (E)-2-octenal, 2,4-heptadienal, (E)-2-nonena, (E,E)-2,4-nonedienal and 2,4-decadienal) were appointed as potential contributors to the off-flavour, since these compounds could be detected during GC-sniffing, and increased in concentration during storage. The eight compounds, that most probably appear as a result of lipoxygenase initiated oxidation of linoleic and linolenic acid during the boiling process, were quantified in freshly boiled and stored boiled potatoes.

Aromas of raw and boiled potatoes were compared using a mild extraction technique, ensuring preservation of the very labile composition of potato aroma during analysis. The extracts were evaluated by GC–MS and GC-sniffing using a panel of four judges. A total of 29 compounds were identified by GC–MS in raw potatoes and 25 in boiled. Twenty compounds were found in both raw and boiled potatoes, but most often in very different concentrations. During GC-sniffing, 33 odours were detected in boiled, and 27 in raw potatoes. Eight odours corresponded to compounds identified by GC–MS. Another four odours could be tentatively identified. It is concluded that the change in aroma during boiling of potatoes depends on compounds from lipid oxidation as well as compounds from other types of reactions, for instance the Strecker-degradation.

Samples of commercial orange juice made by reconstitution of a Brazilian concentrate were subjected to normal storage (5 and 20 °C) and accelerated storage (30, 40 and 50 °C). Sensory quality, content of aroma compounds and colour were measured. Significant changes were seen in all three parameters, and the pattern of changes in both sensory quality and in content of aroma compounds were practically identical during normal and accelerated storage, except for the time span: the changes in quality after 6 months at 20 °C corresponded to the changes after 13 days at 40 °C and after 5 days at 50 °C. Quality changes during storage for half a year can therefore be predicted by 1–2 weeks' accelerated storage. Furthermore, from partial least squares (PLS)-regression of sensory quality on content of 11 aroma compounds it was found that a trained panel's average score of orange taste, orange odour, oxidized taste, oxidized odour and bitterness could be predicted with a high degree of certainty from measurement of the 11 aroma compounds.

The aroma of freshly made and stored reconstituted orange juice was analyzed by GC– MS and GC–FID. The importance of the individual compounds was evaluated by calculation of aroma values. For comparison, the same samples were evaluated by a GC-sniffing technique called GC Odour Profiling, using a panel of five assessors. Both methods showed that there were significant differences between freshly made and stored juice, but the two methods did not always show the same compounds/odours to be important. On the other hand, many similarities were seen, as ethyl butanoate, β -pinene, limonene, octanal and linalool were shown to be important by both methods. In conclusion, both methods proved to be useful for identifying important aroma compounds in orange juice and for discrimination between fresh and stored juice.

Quantification of aroma compounds in a solid food product such as bread can be difficult and time-consuming. Multiple headspace extraction (MHE) was performed on wheat bread crumb by dynamic headspace sampling followed by gas chromatography mass spectrometry analysis. MHE was found to be a successful, relatively simple and reproducible method for the quantification of aroma compounds in bread, since the addition of standards directly into the solid bread sample is not necessary. Furthermore, two different purge conditions within dynamic headspace sampling were successfully used for the quantification of volatiles with low and high breakthrough volumes.

The changes in the VOC composition of industrially produced saveloy were measured with Proton-Transfer-Reaction Mass-Spectrometry (PTR-MS) and HeadSpace Gas chromatography–mass spectrometry (HS-GC–MS) during a six weeks storage period. A decrease in the volatile organic compounds contributing to the fresh aroma of saveloy was the main change observed with both PTR-MS and HS-GC–MS. Samples of four other types of cooked and sliced meat product were measured with PTR-MS in the middle and at the end of the four week shelf-life period. These measurements showed an increase in m/z 69, 71, 87 and 89 for the pork loin and in m/z 61 for the herbal saveloy samples. These ions were assigned to the microbial spoilage markers: acetic acid, 2- and 3-methylbutanol, 2- and 3-methylbutanal, diacetyl and acetoin. Overall, this study shows that PTR-MS has potential for quality control of cooked and sliced meat products.

The influence of pasteurization on non-filtered beers was investigated during accelerated storage (40°C, 41 days). Two beers were produced from the same hopped wort, which was fermented with two different yeast strains. Half of the bottled beers were tunnel pasteurized resulting in four different beer samples. The pasteurization influenced the volatile profile of both fresh beers, but during storage the differences between the volatile profiles of pasteurized and non-pasteurized beers disappeared. During the storage period, the pasteurized beers gave a lower rate of radical formation, as evaluated by electron spin resonance spectroscopy, indicating a better oxidative stability. The pasteurization had no effect on the levels of the pro-oxidative metals iron and copper. Pasteurization slightly increased the protein content of the beers. SDS–PAGE analysis showed that the two beers had different protein profiles, which changed during storage; however, pasteurization of both beers did not affect their protein profiles. The level of thiols were lowered in one beer and raised in the other beer by pasteurization, but during storage the levels of thiols decreased at the same rate in all of the beers. It was concluded that pasteurization had a positive influence on the oxidative stability of non-filtered beer. Copyright © 2013 The Institute of Brewing & Distilling

Influence of malt roasting on the oxidative stability of sweet wort was evaluated based on radical intensity, volatile profile, content of transition metals (Fe and Cu) and thiols. Malt roasting had a large influence on the oxidative stability of sweet wort. Light sweet worts were more stable with low radical intensity, low Fe content, and ability to retain volatile compounds when heated. At mild roasting, the Fe content in the wort increased but remained close to constant with further roasting. Dark sweet worts were less stable with high radical intensities, high Fe content, and a decreased ability to retain volatiles. Results suggested that the Maillard reaction compounds formed during the roasting of malt are prooxidants in sweet wort. A thiol-removing capacity was observed in sweet wort, and it was gradually inhibited by malt roasting. It is possibly caused by thiol oxidizing enzymes present in the fresh malt.

Globally, aquaculture systems with water recirculation experience increasing problems with microbial taste and odor compounds (TOCs) such as geosmin and 2-methylisoborneol (MIB). This study investigated the content of geosmin and MIB in water and the flesh of 200 rainbow trouts from eight recirculated aquaculture systems in Denmark. TOC content in the fish flesh was measured by a dynamic headspace extraction method and was evaluated by a sensory panel. The results showed significant correlations between TOC content in water and fish and between chemical analysis and sensory perception. When geosmin exceeded 20 ng/L in the water, 96% of the fish had an intense muddy flavor, but below 10 ng geosmin/L, 18% of the fish (only 3% in special depuration ponds) had an intense muddy flavor. The results indicate that TOC levels

Export of cocoa beans is of great economic importance in Ghana and several other tropical countries. Raw cocoa has an astringent, unpleasant taste, and flavor, and has to be fermented, dried, and roasted to obtain the characteristic cocoa flavor and taste. In an attempt to obtain a deeper understanding of the changes in the cocoa beans during fermentation and investigate the possibility of future development of objective methods for assessing the degree of fermentation, a novel combination of methods including cut test, colorimetry, fluorescence spectroscopy, NIR spectroscopy, and GC-MS evaluated by chemometric methods was used to examine cocoa beans sampled at different durations of fermentation and samples representing fully fermented and dried beans from all cocoa growing regions of Ghana. Using colorimetry it was found that samples moved towards higher a* and b* values as fermentation progressed. Furthermore, the degree of fermentation could, in general, be well described by the spectroscopic methods used. In addition, it was possible to link analysis of volatile compounds with predictions of fermentation time. Fermented and dried cocoa beans from the Volta and the Western regions clustered separately in the score plots based on colorimetric, fluorescence, NIR, and GC-MS indicating regional differences in the composition of Ghanaian cocoa beans. The study demonstrates the potential of colorimetry and spectroscopic methods as valuable tools for determining the fermentation degree of cocoa beans. Using GC-MS it was possible to demonstrate the formation of several important aroma compounds such 2-phenylethyl acetate, propionic acid, and acetoin and the breakdown of others like diacetyl during fermentation. Practical Application: The present study demonstrates the potential of using colorimetry and spectroscopic methods as objective methods for determining cocoa bean quality along the processing chain. Development of objective methods for determining cocoa bean quality will be of great importance for quality insurance within the fields of cocoa processing and raw material control in chocolate producing companies.