Flavor Profile Analysis Research Articles

Effect of ultrasound-assisted Maillard reaction on functional properties and flavor characteristics of Oyster protein enzymatic hydrolysates

To address the delamination phenomenon during storage and flavor characteristics of Oyster protein hydrolysates (OPH). In this study, xylo-oligosaccharides (XOS) were selected to covalently graft with OPH through ultrasound-assisted Maillard reaction, and the effect of ultrasound-assisted Maillard reaction on the structure, functional properties, and flavor characteristics of OPH were investigated. The results revealed that the ultrasound treatment led to a 1.46-fold increase in the degree of grafting compared with the conventional wet-heat Maillard reaction methods. Structural analyses at various levels indicated substantial alterations in the OPH structure following the ultrasound-assisted Maillard reaction. More ordered α-helical secondary structures were shifting to random coiling, the tertiary structure showed more stretching changes, and the surface structure was characterized by loose and porous features. Compared with OPH, the solubility of the ultrasound-assisted Maillard reaction products (OPH-U-M) increased from 54.67% to 70.14%, leading to a notable enhancement in storage stability. Flavor profile analysis demonstrated a decrease in unsaturated aldehydes and ketones presenting fishy and bitter aromas, while an increase in presenting meat aroma compounds was observed in OPH-U-M. Furthermore, OPH-U-M exhibited superior antioxidant properties with DPPH and ABTS radical scavenging abilities enhancing 46.05% and 42.09% in comparison with OPH, respectively. The results demonstrated that covalently binding with XOS under ultrasonication pretreatment endowed OPH with superior functional properties (including solubility, storage stability, and antioxidant activity), and the improvement of flavor profile. This study can provide theoretical guidance and practical implications for promoting the processing applications of oyster protein.

Flavor profile analysis of grilled lamb seasoned with classic salt, chili pepper, and cumin (Cuminum cyminum) through HS-SPME-GC-MS, HS-GC-IMS, E-nose techniques, and sensory evaluation on Sonit sheep

In this study, the volatile flavor profiles of grilled lamb seasoned with salt, chili pepper, and cumin were analyzed employing HS-SPME-GC–MS, HS-GC-IMS, E-nose, and sensory evaluation techniques. The E-nose was found effective in differentiating the samples seasoned variously. A total of 67 volatile compounds were identified by HS-SPME-GC–MS, and 59 by HS-GC-IMS. The PCA demonstrated a correlation between the seasonings and the volatile compounds, with five principal components accounting for 99.54% of the total variance. 1-octen-3-ol, 3-furanmethanol, acetic acid, and heptanal were introduced by salt; compounds like propyl acetate were correlated with chili pepper; a broader range, including ethyl 3-methylbutanoate and high concentrations of alpha-pinene, was associated with cumin. Samples seasoned with all three ingredients showed similarities to those associated with cumin, alongside unique compounds such as gamma-octalactone and alpha-pinene. Sensory evaluations by consumers indicated that the combination of these seasonings significantly enhanced the overall acceptability of the grilled lamb. Practical applicationUtilizing modern analytical techniques, this study has successfully revealed the distinct impacts of seasonings—salt, chili pepper, and cumin—on the flavor profile of grilled lamb. By providing experimental data on how each seasonings influence the flavor profile of grilled lamb prepared with Sonit sheep. The research offers theoretical foundation for the development of grilled lamb products. By conducting a thorough comparison between GC-MS and GC-IMS, this study has expanded the understanding of the distinct characteristics of these two technologies. It has also provided a clearer analysis of some flavor compounds dimers produced in GC-IMS system.

Effects of solid-state fermentation of seaweed (Caulerpa racemosa) on antioxidant assay and flavour profile

The effects of solid-state fermentation (SSF) of Caulerpa racemosa on antioxidant properties (total phenolic content (TPC), 2, 2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging, Ferric-reducing antioxidant power (FRAP)) and flavour profile were investigated. Additionally, sensory acceptability (9-Point Hedonic Test) and satiety analysis (10-Scale Intention) of oat drinks incorporated with SSF of C. racemosa were also studied. Results of SSF C. racemosa demonstrated that significantly (p<0.05) higher content in TPC, DPPH, IC50 and FRAP (312.30±5.76 mg GAE/100 g, 25.96±0.17 mg AA/100 g, 46.22±0.31 mg/mL, 1106.72±21.82 mg TE/100 g and 206.80±4.76 mg GAE/100 g, respectively). Flavour profile analysis indicated the presence of antimicrobial volatile siloxane compounds; hexamethylcyclotrisiloxane and octamethylcyclotetrasiloxane. These -siloxane group compounds are known to have antioxidant, defoaming, and release coating properties. In addition, results obtained from the sensory evaluation showed that the addition of a different amount of SSF C. racemosa did not significantly (p>0.05) affect the acceptability of instant oat drinks. However, oat drinks incorporated with SSF C. racemosa significantly (p<0.05) increased in fullness from the satiety study. Therefore, value-added SSF C. racemosa can be incorporated into food products to increase its nutritional properties and fullness without affecting the taste.

Identification and evaluation of fishy odorants produced by four algae separated from drinking water source during low temperature period: Insight into odor characteristics and odor contribution of fishy odor-producing algae

Disgusting fishy odor could break out inside oligotrophic drinking waterbody in winter with low temperature. Nevertheless, fishy odor-producing algae and corresponding fishy odorants were not very clear, odor contribution of fishy odorant and odor-producing algae to overall odor profile were also not well understood. In this study, the fishy odorants, produced by four algae separated from Yanlong Lake, were identified simultaneously. Odor contribution of identified odorant, separated algae to overall fishy odor profile were both evaluated. The results indicated Yanlong Lake was mainly associated with fishy odor (flavor profile analysis (FPA) intensity: 6), eight, five, five and six fishy odorants were identified and determined in Cryptomonas ovate, Dinobryon sp., Synura uvella, Ochromonas sp., respectively, which were separated and cultured from water source. Totally sixteen odorants with concentration range of 90–880 ng/L, including hexanal, heptanal, 2,4-heptadienal, 1-octen-3-one, 1-octen-3-ol, octanal, 2-octenal, 2,4-octadienal, nonanal, 2-nonenal, 2,6-nonadienal, decanal, 2-decenal, 2,4-decadienal, undecanal, 2-tetradecanone, were verified in separated algae and associated with fishy odor. Although more odorants’ odor activity value (OAV) were lower than one, approximately 89%, 91%, 87%, 90% of fishy odor intensities could be explained by reconstituting identified odorants for Cryptomonas ovate, Dinobryon sp., Synura uvella, Ochromonas sp., respectively, suggesting synergistic effect could exist among identified odorants. By calculating and evaluating total odorant production, total odorant OAV and cell odorant yield of separated algae, odor contribution rank to overall fishy odor should be Cryptomonas ovate (28.19%), Dinobryon sp. (27.05%), Synura uvella (24.27%), Ochromonas sp. (20.49%). This is the first study for identifying fishy odorants from four actually separated odor-producing algae simultaneously, this is also for the first time evaluating and explaining odor contribution of identified odorant, separated algae to overall odor profile comprehensively, this study will supply more understanding for controlling and managing fishy odor in drinking water treatment plant.

A multi-omics-based investigation into the flavor formation mechanisms during the fermentation of traditional Chinese shrimp paste

The fermentation process of traditional shrimp paste is closely associated with the production of flavor substances, but the formation mechanism of key aroma components is still unclear. In this study, a comprehensively flavor profile analysis of traditional fermented shrimp paste was carried out by E-nose and SPME-GC–MS. A total of 17 key volatile aroma components with OAV > 1 contributed greatly to the overall flavor formation of shrimp paste. In addition, high-throughput sequencing (HTS) analysis revealed that Tetragenococcus was the dominant genera in the whole fermentation process. Moreover, metabolomics analysis showed that the oxidation and degradation of lipids, protein, organic acids and amino acids produced a large number of flavor substances and intermediates, which laid the foundation for the Maillard reaction in term of generating the distinct aroma of the traditional shrimp paste. This work will provide theoretical support for the realization of flavor regulation and quality control in traditional fermented foods.

Changes in odorants and flavor profile of heat-processed beef flavor during storage.

Flavor quality changes of heat-processed beef flavor (HPBF) upon storage are greatly affected by storage conditions. Flavor characterization of HPBF stored for 168 days resulted in 17 key odor-active compounds having flavor dilution factors log3 FD ≥ 3 and odor activity values >1. Based on the concentration changes of these key odorants, a total of 13 HPBF samples were divided into four groups by hierarchical cluster analysis. Combined with flavor profile analysis, the overall flavor of HPBF gradually changed from a characteristic beef aroma to burnt and fermented soybean paste-like notes. Some of the 17 key odorants, such as 2-methyl-3-furanthiol, 2-furfurylthiol, methyl furfuryl disulfide, and difurfuryl disulfide, contributed to the characteristic beef aroma of the freshly prepared product and in the early stage of storage. On the other hand, the odor-active compounds 2-methylbutanal, dimethyl disulfide, dimethyl trisulfide, and 2-ethyl-3,5-dimethylpyrazine were associated with the later stage of storage showing a positive correlation with the intensity of burnt and fermented soybean paste-like notes. A molecular understanding of flavor profile changes of HPBF during storage will provide the basis for developing characteristic beef aroma notes and maintaining the keeping quality of beef products upon storage. PRACTICAL APPLICATION: The relationship between sensory quality and changes in odorant concentration of heat-processed beef flavor during storage will provide the molecular basis for developing high-quality thermal reaction meat flavorings.

Qualitative Changes and Flavour Profile of Banana (Musa spp) Wine during Ageing

Background: Banana is a commercial fruit of many tropical and sub-tropical nations. India is the largest producer of banana in the world. The fruit is a valuable source of carbohydrates, phenolics compounds, minerals and dietary fibre. Due to bumper production, seasonality and market gluts, huge post-harvest losses are recurring phenomena in many banana growing states in India. Hence, the present study was undertaken to evaluate the suitability of some commercial banana cultivars in the development of wine and to evaluate the qualitative changes during ageing. Methods: Wine was prepared from banana varieties (Poovan, Grand Naine, Yangambi (KM-5), Karpooravalli and Palyankodan) in 1:1 and 1:2 dilutions of pulp and water. The TSS content of the substrate was raised to 20°Brix, followed by addition of yeast @ 1.25 g/l. The must was treated with Potassium Metabisulphite (KMS) @ 0.05 g/L to inhibit the growth of other microorganisms. Fermentation was carried out for 15 days, followed by clarification and subjected to ageing for 2 months. Result: During ageing of wine, the pH and alcohol content showed an increasing trend whereas titratable acidity, total soluble solids, ascorbic acid and phenols showed a decreasing trend. The flavour profile analysis of wine revealed that ethanol, ethyl hydrogen succinate and glycerin were the major flavour compounds in banana wine. After the completion of ageing, alcohol content of banana wine ranged from 8.40 to 9.64%, phenols were in the range of 40.50 to 56.25 mg 100 g-1 and total soluble solids varied between 3.6 and 4.5° Brix. Wine prepared from the Poovan variety had the highest overall acceptability score throughout the ageing period.

Joint majorization of waterworks and secondary chlorination points considering the chloric odor and economic investment in the DWDS using machine learning and optimization algorithms

The traditional methods of increasing the chlorine disinfectant dosage in the drinking water distribution system (DWDS) to control microorganisms and improve the safety of drinking water quality are subjected to several challenges. One noticeable problem is the unpleasant odor generated by chlorine and chloramines. However, the generally proposed chlorine dosage optimization model ignores the chloric odor distribution in the DWDS. This study proposes a comprehensive multi-parameter water quality model and aims to balance the trade-offs between: (i) minimize the flavor profile analysis (FPA) degree of the chloric odor produced by chlorine and chloramines in the DWDS, and (ii) minimize the economic investment (chlorine dosage and operation cost). EPANET and back propagation (BP) network integrated with the Borg algorithm were employed as innovative approaches to simulate the chlorine, chloramines, and chloric odor intensity in the DWDS. Moreover, the application of the multi-parameter model was demonstrated in a real-world DWDS case study. 0.5 mg-Cl2/L (mg/L) chlorine at 8 secondary chlorination points was added to the DWDS as an optimized chlorine dosing scheme considering the olfactory and financial objective functions simultaneously. When switching to a superior water source, the FPA of the chloric odor in DWDS increased by a maximum of 1.4 at most if the initial chlorine dosage remained as before. To avoid the occurrence of chloric odor and also control the residual free chlorine (residual chlorine) at a suitable value, the initial and secondary chlorine dosages were optimized to 0.4 mg/L and 0.3 mg/L, respectively. Under this condition, the initial chlorine dosage was reduced by 50% compared to the original operation scheme in City J, China, the qualification rate of the residual chlorine reached 97.2%, basically consistent with that before water source switching, and the chloric odor intensity of the DWDS was controlled below FPA 3.4.

Olfactory Threshold Concentration of Two Typical Earthy-Musty Odour Compounds in Black Carps and Bighead Carps

2-methylisoboneol (2-MIB) and geosmin are two typical earthy-musty odour compounds in freshwater. In order to investigate the olfactory thresholds of 2-MIB and geosmin in black carp (Mylopharyngodon piceus) and bighead carp (Hypophthalmichthys nobilis), an improved and optimized pre-treatment method of adsorbing the earthy-musty odours combined with the technology of gas chromatography following microwave distillation-headspace solid-phase microextraction was developed. The fish back muscle samples were placed in vials with the 2-MIB/geosmin solution and reached the adsorption equilibrium. Some samples were evaluated by a panel of ten members using Flavour Profile Analysis (FPA) method, the remaining sample was used for instrumental analysis. In fish muscle blocks, it took 90 and 105 min to establish the absorption equilibrium of 2-MIB and geosmin, respectively. The olfactory thresholds of 2-MIB in the bodies of black carps and bighead carps were 0.35 μg/kg and 0.30 μg/kg, respectively, while the geosmin thresholds were 0.59 μg/kg and 0.51 μg/kg, respectively. The concentrations of 2-MIB and geosmin in the bodies of black carps were slightly higher than in bighead carps, which were probably caused by the differences in the body fat content and the volatility of 2-MIB and geosmin.

The key aroma compounds and sensory characteristics of commercial Cheddar cheeses

To study the key aroma components and flavor profile differences of Cheddar cheese with different maturity and from different countries, the flavor components of 25 imported commercial Cheddar cheese samples in the China market were determined by gas chromatography-mass spectrometry. The quality and quantity of 40 flavor compounds were analyzed by gas chromatography-olfactometry among 71 aroma compounds determined by gas chromatography-mass spectrometry. Combined with odor activity value calculation, principal component analysis (PCA) was conducted to analyze the relationship among 26 flavor compounds with odor activity values >1 and the maturity of Cheddar cheese. The PCA results showed significant differences between the group of mild Cheddar cheese and the groups of medium Cheddar cheese and mature Cheddar cheese, and no significant differences were observed between medium Cheddar cheese and mature Cheddar cheese. According to the results of PCA and consumers' preference test, representative Cheddar cheese samples with different ripening times were selected for the flavor profile analysis. Partial least squares regression analysis was conducted to obtain the relationship between sensory properties and flavor compounds of different Cheddar cheeses. Based on partial least squares regression analysis, 1-octen-3-one, hexanal, acetic acid, 3-methylindole, and acetoin were positively correlated with milky, sour, and yogurt of mild Cheddar cheese. Dimethyl trisulfide, phenylacetaldehyde, ethyl caproate, octanoic acid, and furaneol and other compounds were positively correlated with fruity, caramel, rancid, and nutty notes of the medium and mature Cheddar cheeses.

Effects of different stabilization techniques on the shelf life of cold brew coffee: Chemical composition, flavor profile and microbiological analysis

Cold brew coffee is a beverage prepared at low temperatures and over long brewing times resulting in particular physicochemical and sensory characteristics. This type of coffee is usually consumed immediately after preparation or after short storage in refrigerated conditions. However, in recent years many commercial coffee vendors started investing in ready-to-drink cold brew coffees packaged for extended storage. These products present the potential problem of microbial and sensorial alteration. In this study we evaluated five different stabilization techniques with the aim to extend the shelf life of the cold brew coffee while preserving its peculiar organoleptic properties, e.g. HPP (High Pressure Processing), microfiltration, UV irradiation, pasteurization and blast chilling process. The effects were investigated over four months, evaluating the caffeine and the chlorogenic acids contents by HPLC-DAD analysis and carrying out anevaluation of selected volatile compounds by HS-SPME-GC-MS. After four months of storage, the samples treated with pasteurization and HPP maintained a stable content of caffeine and chlorogenic acids, guaranteeing also the microbiological safety of the beverage. At the same shelf-time, the pasteurized samples showed an unaltered flavor profile, while a decrease of about 25% of the total content of volatile compounds was registered for the HPP sample.

Comparative flavor profile analysis of four different varieties of Boletus mushrooms by instrumental and sensory techniques

Mushrooms from different varieties and manufacturing methods show different flavor profiles. In order to understand the sensory attributes and aroma compounds of boletus, the discrepancy of aroma profile in four varieties of boletus was determined using gas chromatography–olfactometry combined with sensory analysis and partial least squares regression analysis (PLSR). Sensory analysis revealed that Boletus Edulis had potent roasted and buttery attributes, Boletus Aereu exhibited woody note and Boletus Auripes Pk presented powerful floral and smoky aromas, while Boletus Rubellus Krombh showed weakness in five sensory attributes. The quantitative analysis revealed that the dominant volatiles in boletus samples were esters, aldehydes, acids, alcohols, pyrazines, ketones and phenols. A total of 42 potent aroma compounds (OAVs > 1) were determined by aroma extract dilution analysis and quantitative analysis. 1-Octen-3-ol and 2,5-dimethylpyrazine were the potent aroma compounds among four boletus samples. In addition, the key aroma compounds were 3-(methylthio)propionaldehyde and 2,6-dimethylpyrazine in Boletus edulis. Isovaleric acid, 2,6-dimethylpyrazine, benzeneacetaldehyde and (E)-2-octenal were the key aroma compounds in Boletus aereu. In Boletus auripes Pk, isovaleric acid, 3-ethylphenol and 2,6-dimethylpyrazine were the key aroma compounds, while 3-methylvaleric acid, isovaleric acid and 2,3-dimethylpyrazine significantly contributed to the aroma of boletus rubellus Krombh. Indeed, PLSR indicated that significant difference on aroma resulted from different varieties of boletus.

Determination of the odor threshold concentrations and partition coefficients of isothiocyanates from Brassica vegetables in aqueous solution

Isothiocyanates (ITCs) are products of the enzymatic breakdown of glucosinolates and may cause pungent flavor notes in vegetables. Limited data on odor threshold concentrations (OTCs) and odor quality descriptors of ITCs exist in literature. These parameters were determined in aqueous samples for 19 isothiocyanates found mainly in Brassica vegetables. Thresholds and odor quality descriptors were ascertained by panelists using flavor profile analysis (FPA). The odor threshold concentrations of ITCs range from 0.005 × 10−3 (octyl ITC) to 0.2 × 10−3 (ethyl ITC) g/L and ITCs were mainly characterized by sulfur, garlic, and Brassica vegetable-like notes. Correlation coefficients were between 0.946 (octyl ITC) and 0.996 (3-(methylthio)propyl ITC) and proved convincing results of OTCs using FPA.Partition coefficients were determined in water, artificial saliva and human saliva to provide an insight into behavior of ITCs in two-phase liquid/air systems. Partition coefficients (K) for human saliva are significantly different from other matrices nevertheless the profile of ITCs K values in water and saliva buffer solution were similar. In human saliva the highest K values were observed for octyl, hexyl and cyclohexyl ITCs, and the lowest for cyclopropyl, benzyl, allyl ITCs. Obtained data provide essential and previously unknown sensory properties for future flavor studies.

Debittering of cold pressed grapefruit seed oil by metal‐organic framework adsorbents

The aim of this study was to remove bitterness from cold pressed grapefruit seed oil. Seven different metal-organic frameworks and three natural clays (commercial bleaching earth, zeolite, and sepiolite) were used as adsorbents. In addition, water washing and solvent extraction treatments were done. After the treatments, oil physicochemical properties, fatty acid, sterol, tocopherol and flavonoid compositions, sensory flavor profile analysis, and consumer tests were completed. Results indicated that adsorbent treatments were better for oil color, turbidity, free fatty acidity, and p-anisidine values than those of the washing and extraction treatments. Although there was no significant change in oil fatty acid and sterol composition, some loss in tocopherol content was observed after the treatments. Sensory descriptive analysis indicated that oil bitterness, spicy, and throatcatching scores decreased by 62.79%, 42.42%, and 58.97% by chromium metal-organic framework (Cr-MOF) treatment. In conclusion, Cr-MOF treatment successfully removed the bitterness from cold pressed grapefruit seed oil. Practical applications The bitter taste of cold pressed grapefruit seed oil was almost totally removed by adsorbent treatment with the laboratory synthesized chromium metal-organic frameworks. Sensory flavor profile analysis and consumer test indicated that the treated oil can be directly consumed as edible oil. This method could have practical importance for those who interested to produce and use cold pressed grapefruit seed oils for edible purposes.

Source water odor in one reservoir in hot and humid areas of southern China: occurrence, diagnosis and possible mitigation measures

BackgroundIdentifying typical odor-causing compounds is essential for odor problem control in drinking water. In this study, aiming at a major water source reservoir in hot and humid areas in southern China, which encountered seasonable odor problems in recent years, an integrated approach including comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometry (GC × GC–TOFMS), flavor profile analysis (FPA) and quantitative real-time polymerase chain reaction (qPCR) was adopted to investigate the odor occurrence.ResultsThe results indicated that earthy–musty odor is blamed to the seasonable odor problems, and it is consistent with the complaints results from consumers. Fifty-four typical odor compounds were investigated in the reservoir and twelve were detected, of which, 2-methylisoborneol (2-MIB) was significantly increased during the odor event. Pseudanabaena sp. is the dominant species in the reservoir, which can be further represented by the number of mic gene with qPCR method (R2 = 0.746, P < 0.001). Oxygen consumption (CODMn) and dissolved organic carbon (DOC) have great influence on growth of Pseudanabaena sp., and the release of 2-MIB from the Pseudanabaena sp. cells is affected by temperature and light.ConclusionOur findings demonstrated that 2-MIB is the odor-caused substance in the reservoir and Pseudanabaena sp. is the main 2-MIB producer, which was confirmed as a benthic filamentous algae. Due to CODMn and DOC have great influence on Pseudanabaena sp. growth, further measures to reduce the CODMn and DOC input should be performed. We also demonstrated that the 2-MIB release is affected by temperature and light. The risk of sudden increase of 2-MIB will be reduced by raising the depth of water in the reservoir. Our study will improve the understanding of T&O problems in this city, as well as in other hot and humid area.

Factors affecting the water odor caused by chloramines during drinking water disinfection

Chloramine disinfection is one of the most common disinfection methods in drinking water treatment. In this study, the temporal variability of water odors during monochloramine auto-decomposition was investigated to elucidate the characteristics of odor problems caused by adopting chloramine disinfection in tap water. Odor intensities and dominant odorant contributions were determined using the flavor profile analysis (FPA) and odor active value (OAV), respectively. During auto-decomposition of monochloramine, Cl2/N molar ratio, pH, temperature, and the presence of NOM all affected odor intensity and odor temporal variation in drinking water. In general, decreasing pH from 8.5 to 6.0 led to increasing perceived odor intensity due to the formation of dichloramine. The major odorants responsible for chlorinous odor under acidic and non-acidic conditions were dichloramine and monochloramine, respectively. Chloraminated water with a Cl2/N molar ratio of 0.6 or NOM concentration <2 mg-C L−1 inhibited odor intensity. Furthermore, the influence of rechlorination on chlorinous odor intensity for chloraminated water should not be neglected. The results of this study will be beneficial for the control of chlorinous odors caused by chloramine disinfection in drinking water.

Experimental Study on the Palatability Impacts of Potable Water as a Hydronic Medium

Hydronic systems installed in buildings utilize water to transport thermal energy within the building for heating and cooling purposes. These systems can be closed loop, where the water is chemically treated and circulated indefinitely, or they can be open loop, where the water is not treated and is effluxed as a result of occupant activities, such as bathing or cooking. Water in an open loop system may circulate within the system for a limited time before it is extracted from the system by occupant activities and replaced with new water from the local water supply. The implementation of open loop hydronic systems is becoming more common in multi-unit residential buildings, even though a number of questions regarding the use of such systems remain unanswered. One concern regarding the use of circulated potable water for heating purposes is the potential effects on the occupant perceptions of the palatability of the service water being delivered to their suites. In an open-loop HVAC system (Heating Ventilating, Air Conditioning System), heating water is subject to repeated thermal cycles and continuous recirculation, which creates the potential for chemical alterations of the materials present in the water or leaching of materials from the equipment and piping. Through the use of Flavor Profile Analysis (FPA) established by the American Water Works Association, and a multi-unit HVAC system constructed in a controlled environment, the palatability effects of the operational system were evaluated for a number of scenarios. The collected feedback from the study participants was then tabulated to quantify the impacts of using potable water as a recirculating heating medium on the perceptions of the occupants. The resulting observations led us to conclude that utilizing potable water as a heating medium has a negligible effect on the palatability of water in the system for average retention times under one day, and a non-objectionable, but noticeable, effect for higher average retention times.

Total Intensity of Odor: A New Method to Evaluate Odors

Unpleasant odors in drinking water can have a negative effect on consumer confidence. In fact, consumers often perceive that if their water smells bad, then it must be bad and unsafe to drink. Compliance for odor aesthetics of drinking water in the United States is based on a secondary standard using the threshold odor number (TON) method, a dilution‐to‐threshold test. However, this test has been subject to criticism in the drinking water community for being a poor measure of consumer acceptance. As a result, many utilities have turned to flavor profile analysis (FPA) to better predict consumer acceptance. However, FPA requires a trained panel, and TON remains the recommended procedure for regulatory compliance. The Metropolitan Water District of Southern California, in collaboration with Tufts University, developed a new, robust odor testing method called total intensity of odor, which offers a valid alternative for compliance purposes.

Identification and quantification of nuisance odors at a trash transfer station

The objective of this study was to evaluate the effectiveness of a modified Odor Profile Method (OPM) at a trash transfer station (TTS). An updated Landfill Odor Wheel was used to define odor character and distinguish among odor sources. The Flavor Profile Analysis (FPA) intensity scale was used to rank the relative intensity of the various odor characters defined by the odor wheel and to understand how each odor profile changed off site. Finally, the odor wheel was used to select the appropriate chemical analysis to identify the odorants causing the odors identified by the human panelists. The OPM was demonstrated as an effective tool for characterizing and distinguishing odor sources at a TTS. Municipal solid waste (MSW) odors were characterized as rancid, sulfur, and fragrant; rancid odors were dominant in the odor profile on-site, while sulfur odors dominated off-site. Targeted chemical analysis was used to identify odorants potentially responsible for odors at the site. Methyl mercaptan (rotten vegetable) and hydrogen sulfide (rotten egg) were identified as the odorants most likely to be responsible for the sulfur odors at the site. Acetaldehyde (sweet, fruity), acetic acid (vinegar), and butyric acid (rancid) were identified as the odorants mostly likely to be causing the rancid and sour odors. Terpenes/pine odors were observed near the greenwaste pile. Results confirm that the OPM, together with properly selected chemical analyses, can be a useful tool for identifying and quantifying the sources of odors.

Source-water odor during winter in the Yellow River area of China: Occurrence and diagnosis

Yellow River source water has long suffered from odor problems in winter. In this study, odor characteristics, potential odorants, and algae in the source water of six cities (Lanzhou, Yinchuan, Hohhot, Zhengzhou, Jinan and Dongying) along the Yellow River were determined in winter (February to March 2014). According to flavor profile analysis (FPA), moderate to strong fishy odors occurred in all cities, except for Lanzhou. At the same time, mild earthy/musty odors and septic/swampy odors were also detected. The strong fishy odor (FPA intensity, 8.5) in Yinchuan was attributed to the abnormal growth of Dinobryon (cell density, 5.7 × 104 cells/mL), while the fishy odors in Hohhot, Zhengzhou, Jinan, and Dongying might be caused by Melosira and Cyclotella, Cryptomonas, Dinobryon, and Synedra, respectively. Unsaturated aldehydes, which have been reported to cause fishy odors, were not detected in all samples. However, some saturated aldehydes, including hexanal, heptanal, nonanal, decanal, and benzaldehyde, were detected with a total concentration range of 690 ng/L to 2166 ng/L, and might have partly contributed to the fishy odors. In addition, 2-MIB (5.77–21.12 ng/L) and geosmin (2.26–9.73 ng/L) were responsible for the earthy/musty odors in the Yellow River source waters, and dimethyl disulfide (648.2 ng/L) was responsible for the rancid/swampy odor (FPA intensity, 8.0) episode in Yinchuan. This is a comprehensive study reporting on the occurrence and possible reasons for the odor issues in the Yellow River source water during winter.