In the conventional water treatment process,algae have a propensity to breach the filter barriers and potentially seep into the water distribution system,leading to an elevation in taste and odor compounds(T&O com...In the conventional water treatment process,algae have a propensity to breach the filter barriers and potentially seep into the water distribution system,leading to an elevation in taste and odor compounds(T&O compounds).This investigation delved into the seasonal fluctuations of algae penetration and the production of T&O compounds within the treatment units of Reservoir Water Plant 1(W1)and River Water Plant 2(W2).The findings indicated that despite the application of the‘pre-oxidation,coagulation and sedimentation(PCS),sand filtration,and disinfection’process,certain robust-walled filamentous Cyanobacteria,Bacillariophyta species,and small Chlorophyta genera managed to bypass the filters.The leakage of algal cells during autumn at W1 was particularly striking,with a peak of 1,170,000 cells/L.The concurrent assessment of the potential for T&O compound formation revealed an alarming high potential for 2-methylisoborneol(2-MIB)in the water leaving the plants,with concentrations soaring to 197.20 ng/L at W1 in autumn and 54.78 ng/L at W2 in summer.This underscores the significant capacity of residual algal cells to generate T&O compounds.Tracking the retention and penetration dynamics of algal cells across each drinking water treatment stage is crucial for surface water treatment facilities to develop effective operational and management strategies,thereby enhancing the safety and quality of drinking water for the end consumer.展开更多
Taste and odor （T＆O） problems in drinking water frequently occur because of many compounds present in the water, of which trans-1,10-dimethyl-trans-9-decalol （geosrnin） and 2-methylisoborneol （MIB） are well-kno...Taste and odor （T＆O） problems in drinking water frequently occur because of many compounds present in the water, of which trans-1,10-dimethyl-trans-9-decalol （geosrnin） and 2-methylisoborneol （MIB） are well-known. In this study, a fast and effective method was established for simultaneous determination of 10 T＆O compounds, including geosmin, MIB, 2,4,6-trichloroanisole （TCA）, 2-methylbenzofuran, 2-isopropyl-3-methoxypyrazine （IPMP）, 2-isobutyl-3-methoxypyrazine （IBMP）, cis-3-hexenyl acetate, trans,trans-2,4-heptadienal, trans, cis-2,6-nonadienal, and trans-2-decenal in water samples by headspace solid-phase microextraction （SPME） coupled with gas chromatography-mass spectrometry. An orthogonal array experimental design was used to optimize the effects of SPME fiber, extraction temperature, stirring rate, NaC1 content, extraction time, and desorption time. The limits of detection ranged from 0.1 to 73 ng/L were lower than or close to the odor threshold concentrations （OTCs）. All the 10 T＆O compounds were detected in the 14 water samples including surface water, treatment process water and tap water, taken from a waterworks in Lianyungang City, China. MIB and geosmin were detected in most samples at low concentration. Six T＆O compounds （IPMP, IBMP, trans,cis-2,6-nonadienal, 2-methylbenzofuran, trans-2-decenal, and TCA） were effectively decreased in water treatment process （sedimentation and filtration） that is different from cis-3-hexenyl acetate, MIB and geosmin. It is noted that the TCA concentrations at 15.9-122.3 ng/L and the trans,cis-2,6-nonadienal concentrations at 79.9-190.1 ng/L were over 10 times higher than their OTCs in tap water. The variation of the analytes in the all water samples, especially distribution system indicated that distribution system cannot be ignored as a T＆O compounds source.展开更多
The effect of cyanobacterial bloom decay on water quality and the complete degradation of cyanobacterial blooms in a short period were examined by an enclosure experiment in Gonghu Bay of Lake Taihu,China.Water qualit...The effect of cyanobacterial bloom decay on water quality and the complete degradation of cyanobacterial blooms in a short period were examined by an enclosure experiment in Gonghu Bay of Lake Taihu,China.Water quality parameters as well as taste and odor compounds during the breakdown of cyanobacterial blooms were measured.Results showed that the decay of cyanobacterial blooms caused anoxic water conditions,decreased pH,and increased nutrient loading to the lake water.The highest concentrations of dimethyl sulfide （DMS）,dimethyl trisulfide （DMTS）,and β-cyclocitral were observed in the anoxic water,at 62331.8,12413.3,and 1374.9 ng/L,respectively.2-Methylisoborneol was dominant during the live growth phase of cyanobacterial blooms,whereas DMS and DMTS were dominant during the decomposition phase.Dissolved oxygen,pH,and chlorophyll a were negatively correlated with DMS,DMTS,and β-cyclocitral,whereas total phosphorus,total nitrogen,and ammonium （NH4＋-N） were positively correlated with DMS,DMTS,β-cyclocitral,and β-ionone.The experimental results suggested that preventing the anaerobic decomposition of cyanobacterial blooms is an important strategy against the recurrence of a malodor crisis in Lake Taihu.展开更多
In this paper, a method using solid-phase extraction （SPE） and gas chromatography-mass spectro- metry （GC-MS） was developed to simultaneously analyze five taste and odor compounds in surface water, i.e., 2- methyl...In this paper, a method using solid-phase extraction （SPE） and gas chromatography-mass spectro- metry （GC-MS） was developed to simultaneously analyze five taste and odor compounds in surface water, i.e., 2- methylisoborneol （2-MIB）, 2,4,6-trichloroanisole （TCA）, 2-isopropyl-3-methoxy pyrazine （IPMP）, 2-isobutyl-3- methoxy pyrazine （IBMP）, and trans-l,lO-dimethyl- trans-9-decalol （geosmin, GSM）. The mass spectrometry was operated in selective ion monitoring （SIM） mode. Three kinds of SPE columns and three eluting solvents were compared, the C 18 column was chosen as optimum SPE column, and methanol was chosen as the optimum eluting solvent. It was found that the method showed good linearity in the range of 1-200 ng.L^-1 and gave detection limits of 0.5 1.5 ng.L^-1 for individual compounds. Good recoveries （93.5%-108%） and relative standard deviations （1.58%-7.31%） were also obtained. Additionally, concentrations of these taste and odor compounds in Jinan＇s surface and drinking water were analyzed by applying this method, and the results showed that GSM and 2-MIB were the dominant taste and odor compounds in Jinan＇s raw water.展开更多
Agrocybe aegerita is widely popular for its umami taste.This study utilized five enzymes to hydrolyze the non-volatile taste active compounds extracted from A.aegerita,including inorganic ions,organic acids,soluble su...Agrocybe aegerita is widely popular for its umami taste.This study utilized five enzymes to hydrolyze the non-volatile taste active compounds extracted from A.aegerita,including inorganic ions,organic acids,soluble sugars,free amino acids,5′-nucleotides,and small peptides.The taste activity value(TAV)was used to measure the non-volatile taste active components,while the synergistic effects of umami were determined using equivalent umami concentration(EUC).The results showed that the protamex-treated hydrolysate had the highest umami sensory score(7.03)and EUC value(1039.475±2.673)with the most low-molecular-weight peptides(<1 KDa)and soluble sugars,conferring the best overall flavor characteristics.Furthermore,a positive correlation was found between the EUC values and umami sensory scores and acceptability.Overall,the results showed that the protamex-treated A.aegerita hydrolysate had the highest umami taste and acceptability.Thus,this study provides more information for further studies on the umami compounds of A.aegerita and a theoretical basis for the development and utilization of A.aegerita as a condiment.展开更多
To identify the changes in flavor profiles of bone-in lamb loin during cooking,the volatile flavor compounds,free amino acid,and 5ʹ-nucleotide concentration were evaluated by using dynamic headspace sampling-gas chro-...To identify the changes in flavor profiles of bone-in lamb loin during cooking,the volatile flavor compounds,free amino acid,and 5ʹ-nucleotide concentration were evaluated by using dynamic headspace sampling-gas chro-matography-mass spectrometry,electronic bionic system,sensory evaluation.The results showed the total concentration of volatile flavor compounds significantly increased with prolonged cooking time.Nonanal,hexanal,heptanal,1-octen-3-ol,eugenol,eucalyptol,and 3,7-dimethyl-1,6-octadien-3-ol were the key odor compounds.The total free amino acid(TFAA)concentration significantly decreased after heat treatment,but the proportion of umami free amino acids significantly increased with cooking time(P<0.05).The equivalent umami concentration(EUC)first increased then decreased in 100℃group(peak at 1.5 h),compared with the continuous increase in 75℃group.Meanwhile,an analysis of bionic system showed the samples had significant differences in bitterness,astringency,umami,saltiness,and richness.The 5ʹ-nucleotide,and EUC positively correlated with umami and sensory valuation indicators.Bone-in lamb loin heated at 100℃exhibited higher concentrations of alcohols,aldehydes,esters,heterocycles,and higher taste of bitterness and saltiness,while the 75℃groups exhibited higher taste of umami at longer heat times.This study provides a theoretical basis for flavor control of bone-in lamb.展开更多
Quality parameters and storage stability were evaluated through biochemical,textural,and microbial analyses of the Norwegian red sea cucumber Parastichopus tremulus at two different storage temperatures(0℃ and 4℃)ov...Quality parameters and storage stability were evaluated through biochemical,textural,and microbial analyses of the Norwegian red sea cucumber Parastichopus tremulus at two different storage temperatures(0℃ and 4℃)over 17 days.During storage,the pH decreased from 7 to 6.3,the texture became softer decreasing from 47.3 to 0.3 N,while K-value increased from 4 to 52%,microbial counts increased from 2 to 8 log cfu/g and formation of volatiles increased.After storage for 7 days at 0℃ and 5 days at 4℃,the microbial counts exceeded the acceptability for consumption(7 log cfu/g).Microorganisms such as Flavobacterium and Psychrobacter were the main specific spoilage organisms contributing to the deterioration.Prolonged storage favored the Polaribacter and Marinomonas proliferation regardless of storage temperatures.The free amino acid concentration increased from 24 to 86 mg/100 g at both storage temperatures,probably resulting from the autolysis degradation.The pH decrease could be attributed to the production and dissolution of volatile compounds during storage.Odor-active compounds such as aldehydes(decanal,2,4-decadienal,nonanal),ketones(1-octen-3-one,1-penten-3-one),al-cohols(1-octen-3-ol,2-heptanol),aromatics(p-cresol and phenol),indoles(indole)and sulfides(dimethyl di-sulfide and trisulfide)showed increasing levels with storage time,with the highest levels found in the samples stored at 4℃.This is the first study that demonstrate the quality changes on molecular and microbial level occurring during cold storage of sea cucumber P.tremulus.These results can be used for evaluating the shelf-life limiting factors of such species.展开更多
基金supported by Shaanxi Provincial Key Research and Development Project(No.2022ZDLSF06-08)Shaanxi Provincial Key Scientific and Technological Innovation Team,China(No.2023-CX-TD-32)+1 种基金the Key Scientific Research Projects of Education Department of Shaanxi Province,China(No.22JY035)the Project of Youth Talent Lift Program of Shaanxi Association for Science and Technology,China(No.20230447).
文摘In the conventional water treatment process,algae have a propensity to breach the filter barriers and potentially seep into the water distribution system,leading to an elevation in taste and odor compounds(T&O compounds).This investigation delved into the seasonal fluctuations of algae penetration and the production of T&O compounds within the treatment units of Reservoir Water Plant 1(W1)and River Water Plant 2(W2).The findings indicated that despite the application of the‘pre-oxidation,coagulation and sedimentation(PCS),sand filtration,and disinfection’process,certain robust-walled filamentous Cyanobacteria,Bacillariophyta species,and small Chlorophyta genera managed to bypass the filters.The leakage of algal cells during autumn at W1 was particularly striking,with a peak of 1,170,000 cells/L.The concurrent assessment of the potential for T&O compound formation revealed an alarming high potential for 2-methylisoborneol(2-MIB)in the water leaving the plants,with concentrations soaring to 197.20 ng/L at W1 in autumn and 54.78 ng/L at W2 in summer.This underscores the significant capacity of residual algal cells to generate T&O compounds.Tracking the retention and penetration dynamics of algal cells across each drinking water treatment stage is crucial for surface water treatment facilities to develop effective operational and management strategies,thereby enhancing the safety and quality of drinking water for the end consumer.
基金supported by the National Natural Science Foundation of China(No.21007077,51290283)the Ministry of Water Resources’ Special Funds for Scientific Research on Public Causes(No.201201032)
文摘Taste and odor （T＆O） problems in drinking water frequently occur because of many compounds present in the water, of which trans-1,10-dimethyl-trans-9-decalol （geosrnin） and 2-methylisoborneol （MIB） are well-known. In this study, a fast and effective method was established for simultaneous determination of 10 T＆O compounds, including geosmin, MIB, 2,4,6-trichloroanisole （TCA）, 2-methylbenzofuran, 2-isopropyl-3-methoxypyrazine （IPMP）, 2-isobutyl-3-methoxypyrazine （IBMP）, cis-3-hexenyl acetate, trans,trans-2,4-heptadienal, trans, cis-2,6-nonadienal, and trans-2-decenal in water samples by headspace solid-phase microextraction （SPME） coupled with gas chromatography-mass spectrometry. An orthogonal array experimental design was used to optimize the effects of SPME fiber, extraction temperature, stirring rate, NaC1 content, extraction time, and desorption time. The limits of detection ranged from 0.1 to 73 ng/L were lower than or close to the odor threshold concentrations （OTCs）. All the 10 T＆O compounds were detected in the 14 water samples including surface water, treatment process water and tap water, taken from a waterworks in Lianyungang City, China. MIB and geosmin were detected in most samples at low concentration. Six T＆O compounds （IPMP, IBMP, trans,cis-2,6-nonadienal, 2-methylbenzofuran, trans-2-decenal, and TCA） were effectively decreased in water treatment process （sedimentation and filtration） that is different from cis-3-hexenyl acetate, MIB and geosmin. It is noted that the TCA concentrations at 15.9-122.3 ng/L and the trans,cis-2,6-nonadienal concentrations at 79.9-190.1 ng/L were over 10 times higher than their OTCs in tap water. The variation of the analytes in the all water samples, especially distribution system indicated that distribution system cannot be ignored as a T＆O compounds source.
基金supported by the National Water Pollution Control and Management Technology Major Project(No.2012ZX07101-010)the State Key Laboratory of Freshwater Ecology and Biotechnology(No.2011FBZ07)
文摘The effect of cyanobacterial bloom decay on water quality and the complete degradation of cyanobacterial blooms in a short period were examined by an enclosure experiment in Gonghu Bay of Lake Taihu,China.Water quality parameters as well as taste and odor compounds during the breakdown of cyanobacterial blooms were measured.Results showed that the decay of cyanobacterial blooms caused anoxic water conditions,decreased pH,and increased nutrient loading to the lake water.The highest concentrations of dimethyl sulfide （DMS）,dimethyl trisulfide （DMTS）,and β-cyclocitral were observed in the anoxic water,at 62331.8,12413.3,and 1374.9 ng/L,respectively.2-Methylisoborneol was dominant during the live growth phase of cyanobacterial blooms,whereas DMS and DMTS were dominant during the decomposition phase.Dissolved oxygen,pH,and chlorophyll a were negatively correlated with DMS,DMTS,and β-cyclocitral,whereas total phosphorus,total nitrogen,and ammonium （NH4＋-N） were positively correlated with DMS,DMTS,β-cyclocitral,and β-ionone.The experimental results suggested that preventing the anaerobic decomposition of cyanobacterial blooms is an important strategy against the recurrence of a malodor crisis in Lake Taihu.
文摘In this paper, a method using solid-phase extraction （SPE） and gas chromatography-mass spectro- metry （GC-MS） was developed to simultaneously analyze five taste and odor compounds in surface water, i.e., 2- methylisoborneol （2-MIB）, 2,4,6-trichloroanisole （TCA）, 2-isopropyl-3-methoxy pyrazine （IPMP）, 2-isobutyl-3- methoxy pyrazine （IBMP）, and trans-l,lO-dimethyl- trans-9-decalol （geosmin, GSM）. The mass spectrometry was operated in selective ion monitoring （SIM） mode. Three kinds of SPE columns and three eluting solvents were compared, the C 18 column was chosen as optimum SPE column, and methanol was chosen as the optimum eluting solvent. It was found that the method showed good linearity in the range of 1-200 ng.L^-1 and gave detection limits of 0.5 1.5 ng.L^-1 for individual compounds. Good recoveries （93.5%-108%） and relative standard deviations （1.58%-7.31%） were also obtained. Additionally, concentrations of these taste and odor compounds in Jinan＇s surface and drinking water were analyzed by applying this method, and the results showed that GSM and 2-MIB were the dominant taste and odor compounds in Jinan＇s raw water.
文摘Agrocybe aegerita is widely popular for its umami taste.This study utilized five enzymes to hydrolyze the non-volatile taste active compounds extracted from A.aegerita,including inorganic ions,organic acids,soluble sugars,free amino acids,5′-nucleotides,and small peptides.The taste activity value(TAV)was used to measure the non-volatile taste active components,while the synergistic effects of umami were determined using equivalent umami concentration(EUC).The results showed that the protamex-treated hydrolysate had the highest umami sensory score(7.03)and EUC value(1039.475±2.673)with the most low-molecular-weight peptides(<1 KDa)and soluble sugars,conferring the best overall flavor characteristics.Furthermore,a positive correlation was found between the EUC values and umami sensory scores and acceptability.Overall,the results showed that the protamex-treated A.aegerita hydrolysate had the highest umami taste and acceptability.Thus,this study provides more information for further studies on the umami compounds of A.aegerita and a theoretical basis for the development and utilization of A.aegerita as a condiment.
基金financially supported by the Fujian Province External Cooperation Industrialization Project(Project No.2021I1005).
文摘To identify the changes in flavor profiles of bone-in lamb loin during cooking,the volatile flavor compounds,free amino acid,and 5ʹ-nucleotide concentration were evaluated by using dynamic headspace sampling-gas chro-matography-mass spectrometry,electronic bionic system,sensory evaluation.The results showed the total concentration of volatile flavor compounds significantly increased with prolonged cooking time.Nonanal,hexanal,heptanal,1-octen-3-ol,eugenol,eucalyptol,and 3,7-dimethyl-1,6-octadien-3-ol were the key odor compounds.The total free amino acid(TFAA)concentration significantly decreased after heat treatment,but the proportion of umami free amino acids significantly increased with cooking time(P<0.05).The equivalent umami concentration(EUC)first increased then decreased in 100℃group(peak at 1.5 h),compared with the continuous increase in 75℃group.Meanwhile,an analysis of bionic system showed the samples had significant differences in bitterness,astringency,umami,saltiness,and richness.The 5ʹ-nucleotide,and EUC positively correlated with umami and sensory valuation indicators.Bone-in lamb loin heated at 100℃exhibited higher concentrations of alcohols,aldehydes,esters,heterocycles,and higher taste of bitterness and saltiness,while the 75℃groups exhibited higher taste of umami at longer heat times.This study provides a theoretical basis for flavor control of bone-in lamb.
基金funded by the Norwegian University of Sci-ence and Technology(NTNU)by UiT-The Arctic University of Norway through the project SECURE Cristin grant ID 2061344。
文摘Quality parameters and storage stability were evaluated through biochemical,textural,and microbial analyses of the Norwegian red sea cucumber Parastichopus tremulus at two different storage temperatures(0℃ and 4℃)over 17 days.During storage,the pH decreased from 7 to 6.3,the texture became softer decreasing from 47.3 to 0.3 N,while K-value increased from 4 to 52%,microbial counts increased from 2 to 8 log cfu/g and formation of volatiles increased.After storage for 7 days at 0℃ and 5 days at 4℃,the microbial counts exceeded the acceptability for consumption(7 log cfu/g).Microorganisms such as Flavobacterium and Psychrobacter were the main specific spoilage organisms contributing to the deterioration.Prolonged storage favored the Polaribacter and Marinomonas proliferation regardless of storage temperatures.The free amino acid concentration increased from 24 to 86 mg/100 g at both storage temperatures,probably resulting from the autolysis degradation.The pH decrease could be attributed to the production and dissolution of volatile compounds during storage.Odor-active compounds such as aldehydes(decanal,2,4-decadienal,nonanal),ketones(1-octen-3-one,1-penten-3-one),al-cohols(1-octen-3-ol,2-heptanol),aromatics(p-cresol and phenol),indoles(indole)and sulfides(dimethyl di-sulfide and trisulfide)showed increasing levels with storage time,with the highest levels found in the samples stored at 4℃.This is the first study that demonstrate the quality changes on molecular and microbial level occurring during cold storage of sea cucumber P.tremulus.These results can be used for evaluating the shelf-life limiting factors of such species.
