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Use of non-growing Lactococcus lactis cell suspensions for production of volatile metabolites with direct relevance for flavour formation during dairy fermentations
Bunt, B. van de; Bron, P.A. ; Sijtsma, L. ; Vos, W.M. de; Hugenholtz, J. - \ 2014
Microbial Cell Factories 13 (2014). - ISSN 1475-2859 - 9 p.
amino-acid catabolism - complete genome sequence - aroma compounds - cheddar cheese - lactobacillus-helveticus - streptococcus-lactis - proteolytic systems - alpha-ketoglutarate - l-leucine - bacteria
Background Lactococcus lactis is a lactic acid bacterium that has been used for centuries in the production of a variety of cheeses, as these bacteria rapidly acidify milk and greatly contribute to the flavour of the fermentation end-products. After a short growth phase during cheese ripening L. lactis enters an extended non-growing state whilst still strongly contributing to amino acid-derived flavour formation. Here, a research approach is presented that allows investigation of strain- and amino acid-specific flavour formation during the non-growing state. Results Non-growing cells of five selected L. lactis strains were demonstrated to degrade amino acids into flavour compounds that are relevant in food fermentations and differs greatly from production of flavour compounds using growing cells. As observed earlier in other research set-ups and with other microorganisms, addition of NADH, a-ketoglutarate and pyridoxal-5-phosphate was demonstrated to be essential for optimal flavour formation, suggesting that intracellular pools of these substrates are too low for the significant production of the flavour compounds. Production of flavours during the non-growing phase strongly depends on the individual amino acids that were supplied, on the presence of other amino acids (mixtures versus single compounds), and on the strain used. Moreover, we observed that the plasmid-free model strains L. lactis MG1363 and IL1403 produce relatively low amounts of flavour components under the various conditions tested. Conclusions By using this simplified and rapid approach to study flavour formation by non-growing lactic acid bacteria, lengthy ripening periods are no longer required to assess the capacity of strains to produce flavours in the long, non-growing state of dairy fermentation. In addition, this method also provides insight into the conversion of single amino acids versus the conversion of a mixture of amino acids as produced during protein degradation. The generated results are complementary to earlier generated datasets using growing cells, allowing assessment of the full flavour forming potential of strains used as starter cultures in industrial food fermentation processes.
Characterization of volatile compounds in Fen-Daqu - a traditional Chinese liquor fermentation starter
Van-Diep, L. ; Zheng, X. ; Chen, J.Y. ; Han, B.Z. - \ 2012
Journal of the Institute of Brewing 118 (2012)1. - ISSN 0046-9750 - p. 107 - 113.
solid-phase microextraction - gas-chromatography-olfactometry - mass-spectrometry - dilution analysis - aroma compounds - flavor liquor - juices
Fen-Daqu is a saccharifying agent and fermentation starter for the production of Chinese liquor Fen (alcoholic spirit) and Fen traditional vinegar. The volatile compounds produced at seven incubation steps were analysed by HS-SPME-GC-MS. A total of 83 major volatile compounds were identified, including 23 esters, 8 acids, 24 alcohols, 18 ketones and aldehydes, 6 pyrazines and 4 acetals. Data obtained by HS-SPME-GC-MS were subjected to principal component analysis. The trajectory plots of volatile compounds in Fen-Daqu samples obtained during successive steps of incubation were revealed. The major compounds that contributed to discrimination were hexanal, (E)-2-octenal, (Z)-2-octen-1-ol, nonanoic acid, 1-octanol, 2-decen-1-ol, hexyl acetate, (E)-2-octen-1-ol, acetic acid, ethyl acetate, phenylethyl alcohol, ethyl alcohol, octanoic acid, 1-octanol, 3-methyl-2-buten-1-ol and pyrazines.
Arginine metabolism in sugar deprived Lactococcus lactis enhances survival and cellular activity, while supporting flavour production
Brandsma, J.B. ; Kraats, I. van de; Abee, T. ; Zwietering, M.H. ; Meijer, W.C. - \ 2012
Food Microbiology 29 (2012)1. - ISSN 0740-0020 - p. 27 - 32.
amino-acid catabolism - aroma compounds - lactobacillus-helveticus - carbohydrate starvation - dehydrogenase-activity - alpha-ketoglutarate - semihard cheese - bacteria - conversion - aminotransferases
Flavour development in cheese is affected by the integrity of Lactococcus lactis cells. Disintegrated cells enhance for instance the enzymatic degradation of casein to free amino acids, while integer cells are needed to produce specific flavour compounds from amino acids. The impact of the cellular activity of these integer cells on flavour production remains to be elucidated. In this study we investigated whether lactose-deprived L. lactis cells that use arginine as an alternative energy source can extend cellular activity and produce more specific flavours. In cheese experiments we demonstrated that arginine metabolising cells survived about 3 times longer than non-arginine metabolising cells, which suggests prolonged cellular activity. Cellular activity and flavour production of L. lactis was further studied in vitro to enable controlled arginine supplementation. Comparable with the results found in cheese, the survival rates of in vitro incubated cells improved when arginine was metabolised. Furthermore, elongated cellular activity was reflected in 3–4-fold increased activity of flavour generating enzymes. The observed prolonged cellular activity resulted in about 2-fold higher concentrations of typical Gouda cheese flavours. These findings provide new leads for composing starter cultures that will produce specific flavour compounds
Characterisation of volatile components of Pinotage wines using comprehensive two-dimensional gas chromatography coupled to time-of-flight mass spectrometry (GC x GC–TOFMS)
Weldegergis, B.T. ; Villiers, A. de; McNeish, C. ; Seethapathy, S. ; Mostafa, A. ; Górecki, T. ; Crouch, A.M. - \ 2011
Food Chemistry 129 (2011)1. - ISSN 0308-8146 - p. 188 - 199.
solid-phase microextraction - bar sorptive extraction - south-african wines - flavor compounds - alcoholic beverages - madeira wines - white wine - quercus-petraea - aroma compounds - grape variety
As part of the ongoing research into the chemical composition of the uniquely South African wine cultivar Pinotage, the volatile composition of nine young wines of this cultivar was investigated using comprehensive two-dimensional gas chromatography (GC × GC) in combination with time-of-flight mass spectrometry (TOFMS). Headspace solid phase micro-extraction (HS-SPME) using a carboxen/polydimethylsiloxane (CAR/PDMS) fibre was used to extract the volatile compounds from the wine matrix. Extracts were analysed using an in-house developed GC × GC system equipped with a single jet, liquid nitrogen-based cryogenic modulator. In the current study, 206 compounds previously reported in wine and related matrices have been detected in nine Pinotage wines. Positive identification for 48 compounds was performed using authentic standards, while tentative identification of 158 compounds was based on deconvoluted mass spectra and comparison of linear retention indices (LRI) with literature values. Identified compounds included esters, alcohols, aldehydes, ketones, acids, acetals, furans and lactones, sulphur compounds, nitrogen compounds, terpenes, hydrocarbons, volatile phenols and pyrans. Volatile compounds potentially capable of influencing wine aroma are highlighted. Many of the compounds were common to all 9 wines, although volatile components unique to specific samples were also observed. The results represent the most detailed characterisation of volatile constituents of this cultivar reported to date.
Is there a second fragrance gene in rice?
Fitzgerald, M.A. ; Hamilton, N.R.S. ; Calingacion, M.N. ; Verhoeven, H.A. ; Butardo, V.M. - \ 2008
Plant Biotechnology Journal 6 (2008)4. - ISSN 1467-7644 - p. 416 - 423.
oryza-sativa l. - volatile components - microsatellite markers - aroma compounds - brown rice - 2-acetyl-1-pyrroline - compound - varieties - flavor - headspace
Aromatic rice is highly prized by most rice consumers, and many countries cultivate traditional and improved aromatic varieties. 2-Acetyl-1-pyrroline (2AP) is the major aromatic compound in rice, and is believed to accumulate because of an eight-base-pair (8-bp) deletion in an allele at the fragrance locus. In this study, 2AP was quantified and the presence or absence of the fragrance allele (fgr) was determined in 464 samples of traditional varieties of rice from the T.T. Chang Genetic Resources Centre at the International Rice Research Institute. It was shown that a number of aromatic varieties, primarily from South and South-East Asia, do not carry the 8-bp deletion, but 2AP was identified in both raw and cooked rice of these varieties. We suggest that the 8-bp deletion in fgr is not the only cause of aroma, and at least one other mutation drives the accumulation of 2AP. The amount of 2AP in most uniform fgr genotypes was not significantly different from that in aromatic nfgr genotypes, but several fgr genotypes, primarily from South Asia, reproducibly accumulated exceptionally large amounts of 2AP. We suggest that the mutation leading to 2AP in aromatic nfgr varieties possibly originated several times and, through either domestication or evolution, the fgr gene and other alleles leading to 2AP have combined in South Asia, leading to several highly aromatic traditional varieties. The identification of multiple mutations for 2AP will enable rice breeding programmes to select actively for multiple genetic sources of 2AP, leading to the development of highly aromatic and, consequently, high-quality varieties of rice.
In vitro evaluation of genistein bioaccessibility from enriched custards
Sanz, T. ; Luyten, J.M.J.G. - \ 2007
Food Hydrocolloids 21 (2007)2. - ISSN 0268-005X - p. 203 - 211.
green leafy vegetables - beta-carotene - aroma compounds - water emulsions - bioavailability - release - humans - digestion - isoflavones - retention
The suitability of custards with genistein incorporated in the fat phase of the milk to become a new `functional food¿ with good bioaccessibility was evaluated. Intestine bioaccessibility was mainly attributed to the incorporation of genistein into micelles and did depend on fat concentration. In terms of bioaccessibility, a milk fat content of 3% was found to be the optimum. Saliva and pepsin significantly affected the bioaccessibility of genistein in the mouth and the stomach but they did not have an effect on intestine bioaccessibility. The use of carboxymethylcellulose instead of starch as thickening agent significantly reduced bioaccessibility. Similar bioaccessibilities and structure breakdown properties were found among the waxy maize and the tapioca pregelatinized starches, which convert the latest in a good alternative when a cold custard preparation is required. Values of bioaccessibility up to 92% were obtained, so it is concluded that custards are a useful carrier for genistein.
Emulsion flocculation induced by saliva and mucin
Vingerhoeds, M.H. ; Blijdenstein, T.B.J. ; Zoet, F.D. ; Aken, G.A. van - \ 2005
Food Hydrocolloids 19 (2005)5. - ISSN 0268-005X - p. 915 - 922.
oil-in-water - depletion flocculation - beta-lactoglobulin - custard desserts - aroma compounds - release - protein - perception - texture - mouth
Upon consumption of emulsions, mixing with saliva occurs. This article shows that whole saliva and a model mucin (pig gastric mucin, PGM) are able to induce extensive droplet flocculation. Saliva samples collected from several subjects at different times of the day always showed flocculation. However, there was a clear variation between samples from different individuals with respect to the structure of the flocs and reversibility of flocculation upon dilution. Several aspects of PGM-induced flocculation, measured by microscopy, particle size analysis, demixing experiments and rheology pointed to depletion flocculation as the main mechanism of flocculation. However, although depletion may also be an important driving force in saliva-induced flocculation, the required mucin concentration seems to be considerably lower than for PGM. Therefore other interactions, such as bridging or specific binding, may be important as well. The observed aggregation is expected to have implications for understanding sensory properties of emulsions. The viscosities of emulsions measured in vitro in the absence of saliva may deviate from the in vivo viscosities relevant for sensory perception, especially in case of liquid emulsions in which the droplets are not flocculated, such as milk
Development of a high throughput screening method to test flavour-forming capabilities of anaerobic micro-organisms.
Smit, B.A. ; Engels, W.J.M. ; Hylckama Vlieg, J.E.T. van; Wouters, J.T.M. ; Smit, G. - \ 2004
Journal of Applied Microbiology 97 (2004)2. - ISSN 1364-5072 - p. 306 - 313.
lactic-acid bacteria - amino-acids - gas-chromatography - aroma compounds - cheese curd - fermentation - conversion - odorants - origin
Aim: Development of a fast, automated and reliable screening method for screening of large collections of bacterial strains with minimal handling time. Methods and Results: The method is based on the injection of a small headspace sample (100 µl) from culture vials (2 ml) in 96-well format directly into the mass spectrometry (MS). A special sample tray has been developed for liquid media, and anaerobically grown cultures. In principle, all volatile components can be measured, but a representative mass fragment has to be obtained in the MS. Representative masses for 3-methylbutanal, 2-methylpropanal and benzaldehyde are 58, 72 and 105, respectively. In 1 day over 1500 samples could be analysed and the coefficient of variation for the response was
Effect of emulsion properties on release of esters under static headspace, in vivo, and artificial throat conditions in relation to sensory intensity
Weel, K.G.C. ; Boelrijk, A.E.M. ; Burger, J.J. ; Jacobs, M.A. ; Gruppen, H. ; Voragen, A.G.J. ; Smit, G. - \ 2004
Journal of Agricultural and Food Chemistry 52 (2004)21. - ISSN 0021-8561 - p. 6572 - 6577.
flavor release - aroma compounds - liquid emulsions - water emulsions - fat - perception - systems - mouth
The effects of oil content and droplet size distributions of dilute oil-in-water emulsions on release of four esters with different hydrophobicities were studied under in vivo, static headspace, and artificial throat conditions. The effect of oil content on orthonasal and retronasal perceived intensity of ethyl hexanoate was studied using a seven-person panel. With increasing oil content and with a higher hydrophobicity of the aroma compound, a stronger decrease in aroma release was found. This effect was stronger under static headspace conditions than under in vivo and artificial throat conditions, and the sensory intensity of ethyl hexanoate was perceived stronger orthonasally than retronasally. The lowest effective oil content was determined for all systems. Of the compounds tested, droplet size distribution only influenced the in vivo release of geranyl acetate. The artificial throat results correlated well with in vivo release, giving support to the assumption that a thin layer of liquid remaining in the throat after swallowing determines aroma release.
Permeation of volatile compounds through starch films
Yilmaz, G. ; Jongboom, R.O.J. ; Feil, H. ; Dijk, C. van; Hennink, W.E. - \ 2004
Biomacromolecules 5 (2004)2.. - ISSN 1525-7797 - p. 650 - 656.
controlled-release - glassy-polymers - aroma compounds - free-volume - oxygen permeability - hydrogel membranes - solvent-diffusion - sunflower oil - encapsulation - crystallinity
The aim of this study was to gain insight into the factors that affect the permeation of volatiles through starch films. These films were obtained by casting gelatinized starch/water/glycerol mixtures. The films were dried and conditioned under different conditions (temperature and relative humidity) resulting in films that vary in the degree of starch crystallinity and glycerol and water content. The permeation of two model volatiles (carvone and diacetyl) at 20degreesC and at 30, 60, or 90% relative humidity (RH) was analyzed gravimetrically. Further, the solubility of the two model compounds (under conditions where the permeation experiments were carried out) was determined. From the obtained permeation and solubility data, the diffusion coefficients of these compounds in the different starch films were calculated. The crystallinity in the starch films increased with increasing water content of the films during preparation. The water content of the resulting films in turn increased with increasing glycerol and when the films were exposed to a higher RH during drying or conditioning. For films with the same composition, the flux for diacetyl was greater than for carvone. The solubilities of diacetyl and carvone were slightly dependent on the properties of the films. It was found that with increasing starch crystallinity the diffusion coefficient for both compounds decreases, which is probably due to the impermeability of starch crystallites. Interestingly, in films with about the same extent of crystallinity, the diffusion can be described with the free volume model, with water and glycerol determining the amount of free volume.
Influence of flavour absorption by food-packaging materials (low-density polyethylene, polycarbonate and polyethylene terephthalate) on taste perception of a model solution and orange juice
Willige, R.W.G. van; Linssen, J.P.H. ; Legger, A. ; Voragen, A.G.J. - \ 2003
Food Additives and Contaminants 20 (2003)1. - ISSN 0265-203X - p. 84 - 91.
aroma compounds - sorption - quality - storage - film
The influence of flavour absorption by low-density polyethylene (LDPE), polycarbonate (PC) and polyethylene terephthalate (PET) on taste perception of a model solution containing seven flavour compounds and orange juice in glass bottles was studied with and without pieces of the respective plastic films after dark storage at 20°C. Owing to absorption, the amount of flavour compounds in the model solution exposed to LDPE decreased substantially. From the model flavour solution valencene was almost completely absorbed by LDPE, followed to a lesser extent by decanal, hexyl acetate, octanal and nonanone. Less flavour compounds were absorbed from the model solution by PC and PET. In contrast to LDPE, valencene was absorbed in the lowest amounts and decanal in the highest. Limonene was readily absorbed from orange juice by LDPE, while myrcene, valencene, pinene and decanal were absorbed in smaller quantities. Only three flavour compounds were absorbed from orange juice by PC and PET in very small amounts: limonene, myrcene and decanal. Although the flavour content between controls and polymer-treated samples differed substantially, the loss of flavour compounds due to absorption by LDPE, PC and PET did not influence taste perception of a model solution and orange juice significantly up to 29 days of dark storage at 20°C as determined by triangular taste panel tests
Modelling the effect of oil/fat content in food systems on flavour absorption by LLDPE.
Dekker, M. ; Willige, R.W.G. van; Linssen, J.P.H. ; Voragen, A.G.J. - \ 2003
Food Additives and Contaminants 20 (2003)2. - ISSN 0265-203X - p. 180 - 185.
low-density polyethylene - packaging interactions - aroma compounds - aluminum foil - sorption - adhesion - matrix - films - acids - oil
One of the phenomena in food packaging interactions is flavour absorption. Absorption of flavour compounds from food products into food-packaging materials can result in loss of flavour compounds or an unbalance in the flavour profile changing a product's quality. The food matrix influences the amounts of absorbed flavour compounds; the presence of oil or fat especially determines the ability to absorb flavour compounds from the food to the package. On the other hand, the polarity of the flavour compound itself is a characteristic that also influences the level of absorption into synthetic polymers. A model based on the effect of the polarity (log P) of flavour compounds and on their partitioning coefficients between the food (matrix) and the packaging material is described. The model can be used for predicting absorption of flavour compounds from foods into LLDPE. However, an attempt to apply the proposed model on real foods shows serious limitations of the model for (very) low fat products. Predictive values deviate from the measured values, probably due to other interaction phenomena, e.g. with proteins. Predictive and measured values from a product with a substantial amount of fat match much better, suggesting that the model is valid for products having a substantial amount of (free) fat.
Influence of storage Time and Temperature on Absorption of Flavour Compounds from Solutions by Plastic Packaging Materials
Willige, R. ; Schoolmeester, D. ; Ooij, A. van; Linssen, J.P.H. ; Voragen, A.G.J. - \ 2002
Journal of Food Science 67 (2002)6. - ISSN 0022-1147 - p. 2023 - 2031.
low-density polyethylene - aroma compounds - orange juice - food matrix - sorption - polypropylene - diffusion - polymers - limonene - quality
Food packaging, although an integral part of the food chain, has a major drawback in that, often, the packaging material interacts with the flavor constituents of the food, causing either a selective or an extensive loss of desirable food flavors or absorption of undesirable off-flavors from the packaging material, thereby resulting in an eventual loss of quality of the packaged food item. The process is called "scalping" and is of great concern to the food industry, which is always looking out for new avenues in "packaging solutions" for its final product quality needs. The review highlights the various attributes of the scalping process, explores approaches to the reduction of the manifested undesirable effects, and covers other relevant aspects.
Influence of flavour absorption on oxygen permentation through LDPE, PP, PC and PET plastics food packaging
Willige, R.W.G. van; Linssen, J.P.H. ; Meinders, M.B.J. ; Stege, H.J. van der; Voragen, A.G.J. - \ 2002
Food Additives and Contaminants 19 (2002)3. - ISSN 0265-203X - p. 303 - 313.
low-density polyethylene - limonene absorption - aroma compounds - aluminum foil - sorption - adhesion - matrix - films - acids - oil
The effect of flavour absorption on the oxygen permeability of low-density polyethylene (LDPE), polypropylene (PP), polycarbonate (PC) and polyethylene terephthalate (PET) was studied using an isostatic continuous flow system. Polymer samples were exposed to a model solution containing limonene, hexyl acetate, nonanone and decanal at 40°C. After exposure, one part of each sample was analysed for absorbed flavour compounds using a Large Volume Injection GC Ultrasonic 'in vial' extraction method, and from the other part, oxygen permeability was measured in a permeation cell at 25°C. After 8h of exposure, LDPE and PP samples showed a significant linear (R2 = 0.82 and 0.99) increase in oxygen permeability of 21 and 130%, respectively. Owing to swelling of the polymer samples resulting from flavour absorption, the structure of the polymeric network changed (i.e. opened) and consequently increased oxygen permeability. The oxygen permeability of exposed PC showed a significant linear (R2 = 0.78) decrease of 11% after 21 days. PC obviously did not swell like LDPE or PP. Therefore, it was suggested that absorbed flavour compounds occupied or blocked 'microcavities' through which normally oxygen is transported. Absorption of flavour compounds by PET did not affect the oxygen permeability of PET significantly