Volatile Properties Research Articles

The volatile profile of pasteurized leek (Allium ampeloprasum var. porrum) and Brussels sprouts (Brassica oleracea var. gemmifera) (products), as a witness to (bio)chemical reactivity, influenced by pretreatment and successive refrigerated storage

Processing can affect (bio)chemical conversions in vegetables and can act on their volatile properties accordingly. In this study, the integrated effect of pretreatment and pasteurization on the volatile profile of leek and Brussels sprouts and the change of this profile upon refrigerated storage were investigated. Pretreatments were specifically selected to steer biochemical reactivities to different extents. Volatile profiles were analyzed by headspace-solid phase microextraction-gas chromatography-mass spectrometry. For both vegetables, it was observed that different pretreatments prior to a pasteurization step led to diverse volatile profiles. The differences in volatile profiles observed in the different samples were presumably attributed to the different degrees of enzymatic conversions, further conversions of enzymatically formed products and thermally induced reactivities. Interestingly, the observed initial relative differences between volatile profiles of differently pretreated pasteurized samples were still observed after a refrigerated storage of 4 weeks at 4 °C. In conclusion, refrigerated storage only limitedly affected the resulting volatile profile.

Analysis of Floral Scent and Volatile Profiles of Different Aster Species by E-nose and HS-SPME-GC-MS.

Plants from the Aster species are known to be a rich source of bioactive chemical compositions and are popularly known for their medicinal properties. To investigate the relationship between the nine species of Aster, the floral fragrance and volatile profile patterns were characterized using E-nose and HS-SPME-GC-MS. Initial optimization for fragrance analysis was performed with Aster yomena using E-nose by evaluating the scent patterns in different flowering stages. Aster yomena exhibited varied scent patterns in each flowering stage, with the highest relative aroma intensity (RAI) in the full flowering stage. PCA analysis to compare and analyze the scent characteristics of nine Aster species, showed a species-specific classification. HS-SPME-GC-MS analysis of flowers from nine Aster species revealed 52 volatile compounds including β-myrcene, α-phellandrene, D-limonene, trans-β-ocimene, caryophyllene, and β-cadinene. The terpenoid compounds accounted for the largest proportion. Among the nine Aster species flowers, Aster koraiensis had sesquiterpenes as the major component, and the remaining eight varieties had monoterpenes in abundance. These results could distinguish the species according to the scent patterns and volatile components of the nine Aster species. Additionally, flower extracts from the Aster species' plants exhibited radical scavenging antioxidant activity. Among them, it was confirmed that Aster pseudoglehnii, Aster maackii, and Aster arenarius had high antioxidant activity. In conclusion, the results of this study provide fundamental data of the volatile compound properties and antioxidant activity of Aster species, offering basic information of valuable natural sources that can be utilized in the pharmaceutical, perfume, and cosmetic industries.

Generative Adversarial Networks (GAN) and HDFS-Based Realtime Traffic Forecasting System Using CCTV Surveillance

The most crucial component of any smart city traffic management system is traffic flow prediction. It can assist a driver in selecting the most efficient route to their destination. The digitalization of closed-circuit television (CCTV) systems has resulted in more effective and capable surveillance imaging systems for security applications. The number of automobiles on the world’s highways has steadily increased in recent decades. However, road capacity has not developed at the same rate, resulting in significantly increasing congestion. The model learning mechanism cannot be guided or improved by prior domain knowledge of real-world problems. In reality, symmetrical features are common in many real-world research objects. To mitigate this severe situation, the researchers chose adaptive traffic management to make intelligent and efficient use of the current infrastructure. Data grow exponentially and become a complex item that must be managed. Unstructured data are a subset of big data that are difficult to process and have volatile properties. CCTV cameras are used in traffic management to monitor a specific point on the roadway. CCTV generates unstructured data in the form of images and videos. Because of the data’s intricacy, these data are challenging to process. This study proposes using big data analytics to transform real-time unstructured data from CCTV into information that can be shown on a web dashboard. As a Hadoop-based architectural stack that can serve as the ICT backbone for managing unstructured data efficiently, the Hadoop Distributed File System (HDFS) stores several sorts of data using the Hadoop file storage system, a high-performance integrated virtual environment (HIVE) tables, and non-relational storage. Traditional computer vision algorithms are incapable of processing such massive amounts of visual data collected in real-time. However, the inferiority of traffic data and the quality of unit information are always symmetrical phenomena. As a result, there is a need for big data analytics with machine learning, which entails processing and analyzing vast amounts of visual data, such as photographs or videos, to uncover semantic patterns that may be interpreted. As a result, smart cities require a more accurate traffic flow prediction system. In comparison to other recent methods applied to the dataset, the proposed method achieved the highest accuracy of 98.21%. In this study, we look at the construction of a secure CCTV strategy that predicts traffic from CCTV surveillance using real-time traffic prediction analysis with generative adversarial networks (GAN) and HDFS.

Role of maturity status on the quality and volatile properties of mango fruits dried by infrared radiation

Drying characteristics and quality attributes are greatly dependent on the maturity status of fresh fruits. Hence, this work investigated the changes in quality and volatile properties of mangoes at ripening stages (from the lowest to highest degree—RS-1, RS-2, RS-3, RS-4) during infrared drying. Results showed that the total soluble solids/titratable acid, texture, nutrient composition (phenolic, vitamin C, β-carotenoid), and volatile compounds during drying were varied during drying. Moreover, fruits at RS-3 obtained the highest increase in total phenolic (8.72 mg/g), the most dramatic decrease in vitamin C (5.58 mg/g), and the lowest decrease in β-carotenoid contents (56.49 mg/100 g) during drying. After drying, the lower L* values, the higher a* and b* values were obtained for products with higher ripeness. Correspondingly, the color changed from light yellow to dark red-orange. The aroma intensity reduced after drying, and the aroma changed from tangerine and citrus to fruity, orange peel, and pineapple. According to the comprehensive quality evaluation model, the highest evaluation score at RS-3, which was 3.58%–42.90% higher than those of other stages.

Profiling of Volatile Organic Compounds (VOCs) of Wild Edible Durians from Sarawak, Borneo Associated with Its Aroma Properties

Volatile organic compounds determine the aroma properties of durian, and it is an important factor in durian acceptance by consumers. However, limited information is devoted to volatile organic compounds and aroma in wild edible durians. Therefore, the present study aims to characterize and compare the volatile organic compounds and aroma properties of the indigenous wild edible durians from Sarawak, Borneo. Seven genotypes, namely Durio dulcis, Durio graveolens (yellow-fleshed), Durio graveolens (orange-fleshed), Durio graveolens (red-fleshed), Durio kutejensis, Durio oxleyanus, and Durio zibethinus were characterized in this study. Solid phase microextraction combined with gas chromatography-mass spectrometry (SPME GC-MS) was used to detect the volatile organic compounds, while the quantitative descriptive analysis (QDA) method was used to characterize the aroma properties of wild edible durians. A total of 119 volatile organic compounds comprising alcohol, aldehyde, amine, ether, ester, ketone, nitrogen-containing, and sulfur-containing compounds were detected. Ester and alcohol compounds are the most predominant in the composition, especially D. graveolens (yellow- and orange-fleshed), and D. dulcis possessed three to nine times higher relative amount of ester compounds. PCA clearly classified the wild durians into different groups. Based on the QDA analysis, D. kutejensis has the mildest aroma among wild edible durians, while D. dulcis perceived a stronger sweet and grassy aroma. Partially Least Square (PLS) regression model analysis indicated a strong relationship between the volatile organic compounds and the aroma intensity perceived by the panelists. These findings could be the major component in the durian industry, paving the way for breeding efforts to create new cultivars that can improve consumers’ satisfaction.

Screening of the Volatile Composition and Olfactory Properties of Aglianico and Primitivo, Two Southern Italian Red Wines

Gas-chromatography/mass-spectrometry and sensory descriptive analyses were applied to provide new data on volatile and olfactory properties of Aglianico and Primitivo (Zinfandel), Italian red wines of growing interest. The relationships between data sets were investigated by multivariate statistical analyses: Principal Component and Hierarchical Clustering Analyses (PCA, HCA). A total of 35% of the volatiles varied significantly (ANOVA) between the two wines, mostly showing higher amounts in the Aglianico samples. Multivariate analyses showed intra-varietal similarity and inter-varietal diversity in terms of aromatic characteristics. PCA indicated that Aglianico wines were mainly related to the main fermentative alcohols, with a sensory impact, and to terpenols, suggesting a potential discriminating power at a compositional level. Primitivo wines formed two groups, one of which correlated to the floral aroma vector linked to beta-phenethyl acetate and beta-ionone. These findings may be valuable for updating the information on these wines and for future research to improve and obtain more targeted production and communication approaches.

Soil Amendment and Storage Effect the Quality of Winter Melons (Benincasa hispida (Thunb) Cogn.) and Their Juice.

Winter melon fruits were grown in the field using anaerobic soil disinfestation (ASD) and conventional fertilizer alone as the control treatment. Fruits were harvested and stored at 20 °C for 120 d, the juice was processed on day one and day 120, and the effects of soil amendment and 120 d storage on the juice's physical and chemical (sugars, acids, volatile and nutritional compounds) properties were evaluated. Fruit juice extracted from ASD-grown fruit had greater magnitude of zeta potential than the control juice, indicating it was physically more stable than the juice obtained from the control conditions. ASD fruit juice had lower soluble solids content (SSC), and lower volatile compounds that contribute green, grass, and sulfur notes, and negatively influence flavor quality. ASD fruit juice had higher vitamin B5 and cytidine. Juice processed from 120 d stored fruit had less yield due to 12.4-15.6% weight loss. The non-soluble solids content was higher and particle size was larger, and the SSC and individual sugars decreased. However, titratable acidity (TA) increased primarily due to increased citric acid. Out of 16 free amino acids, 6 increased and only 1 decreased. However, three out of five nucleosides decreased; vitamins B1 and B6 increased; vitamins B2, B3 and C decreased. Overall, juice derived from fruit produced using ASD was physically more stable and had less SSC and off-odor volatiles than the control, while the fruit juice of those stored for 120 d had lower SSC and higher TA and nutritional profiles, comparable to freshly harvested fruit.

Differential characterization of volatile components and aroma sensory properties of different types of Hehong tea (Congou black tea)

AbstractTo explore the flavour characteristics and their different molecular mechanisms of different types of Hehong tea (Gongya, GY; Congou, CG and Laocong, LC) from the perspective of dry tea, we investigated their volatile compounds and sensory aroma sub‐attribute characteristics by headspace–solid phase microextraction–gas chromatography–mass spectrometry (HS‐SPME‐GC–MS), quantitative description analysis (QDA), and chemometrics. A total of 42 volatile compounds were identified in Hehong tea, of which alcohol content was the highest, the number of esters was the largest and pyrrole showed the largest differences. The volatile components of GY and LC differed, whereas those of CG and LC were more similar. There were 34 volatile components with a significant difference in the three types of Hehong tea. We established the aroma quantitative system of Hehong tea by using QDA. We found that sweety was probably the symbolic aroma sub‐attribute of Hehong tea, and woody was the characteristic sub‐attribute of LC, and there was a certain correlation among the aroma sub‐attributes. A total of 21 volatile components importantly contributed to the aroma sub‐attributes of Hehong tea. Furthermore, we screened out 18 marker volatile compounds that may be used as important indicators for distinguishing the three types of Hehong tea. Our findings add to our understanding of the flavour characteristics and aromas of the three types of Hehong tea and provide new strategies and thoughts for the evaluation of tea flavour using dry tea.

Effects of Sous Vide Cooking on the Physicochemical and Volatile Flavor Properties of Half-Shell Scallop (Chlamys farreri) during Chilled Storage

This study explored the effects of sous vide (SV) cooking treatments on the physicochemical quality and volatile flavor of half-shell scallop (Chlamys farreri) during 30 d of chilled storage. The vacuum-packed scallop samples were cooked at 70 °C (SV-70) and 75 °C (SV-75) and maintained for 30 min. The samples were compared with the positive control (cooked at 100 °C for 10 min, CK). The results indicate that the total volatile basic nitrogen (TVBN), pH, texture, and malondialdehyde (MDA) content gradually increased, while the myofibrillar protein (MP) extraction rate of the CK, SV-70, and SV-75 samples significantly decreased with increasing chilled storage time. Significantly, the SV cooking treatments maintained a much higher water-holding capacity of scallop muscle, compared with the conventional cooking process at 100 °C. Additionally, the SV-75 cooking treatment maintained relatively stable TVBN, pH, and MDA content, springiness, and shearing force properties of scallop samples, especially during 0-20 d of storage. Volatile flavor analysis showed that a total of 42 volatile organic compounds (VOCs) were detected in the scallop samples, and there were no considerable differences in these VOCs between the CK and SV-75 cooked samples (0 d). Overall, the SV cooking treatments effectively maintained acceptable and stable physicochemical and volatile flavor properties of half-shell scallop samples during chilled storage.

Occurrence of methylsiloxanes in indoor store dust in China and potential human exposure

Methylsiloxanes are synthetic molecules with versatile and extensive applications. Because of their volatile properties, they are easily released from manufactured products and contaminate indoor environments, causing high human exposure. However, available information on their presence in specific microenvironments, and on the related potential risks for human health, is limited. We conducted a survey of sixteen methylsiloxanes species, including three cyclic (D4–D6) and thirteen linear (L4–L16) chemicals, in indoor dust samples from twenty-eight stores representative of six store categories in Beijing, China. Total methylsiloxane concentrations in store dust were 176–54,825 ng/g, depending on the store, with a median of 2196 ng/g. Linear chemicals represented a median proportion of 90.8% of total methylsiloxanes. The measured methylsiloxane concentrations in this study were marginally higher than those reported previously for standard living and working environments. The highest linear and total methylsiloxane concentrations were measured in electronic stores, while the highest cyclic methylsiloxane concentrations were measured in department stores. The presence of methylsiloxanes in the store dust samples was attributed mainly to their release from chemical additives in marketed products. Estimated median total exposure doses under normal and worst-case exposure scenarios were 0.237 and 0.888 ng/kg bw/d, respectively. Further investigation is needed to characterize methylsiloxane distribution in other microenvironments and to evaluate the associated health risks.

Selective sulfidation-vacuum volatilization processes for tellurium and bismuth recovery from bismuth telluride waste thermoelectric material

Bismuth telluride-based alloy materials are currently the best performing thermoelectric materials at near room temperature; however, their production and use generate waste (e.g., cutting waste and failed grains). There is also lack of efficient recycling strategies for the generated waste. In this study, a selective sulfidation-vacuum volatilization method is proposed for recovering bismuth telluride waste. The Gibbs free energies of the sulfidation reaction of bismuth telluride are calculated, the saturated vapor pressure of each substance is analyzed, and the composition of the products is predicted. Based on the differences among the sulfidation and volatile properties of bismuth and tellurium, by adding sulfur to bismuth telluride waste, the composition of the substances was regulated, and efficient separation of tellurium and bismuth was achieved. We combined theoretical calculations and experimental studies to investigate the effect of process conditions on the separation and recovery of tellurium and bismuth. The results show that bismuth was thoroughly sulfereted and tellurium was a pure metal when the mass ratio of sulfur to bismuth telluride was 0.168, the sulfidation temperature was 573 K, and the holding time was 60 min. After sulfidation of the bismuth telluride waste, the sulfides were telluride and bismuthous sulfide. The sulfides, that resulted from sulfureted bismuth telluride production, were treated via vacuum volatilization. The optimal vacuum volatilization condition was 873 K for 120 min. The purities of tellurium and bismuth sulfide obtained by the selective sulfidation-vacuum volatilization experiment were >99%. The distribution ratios of tellurium and bismuth were 98.46% and 99.59%, respectively. The method thoroughly separated tellurium and bismuth from bismuth telluride waste, considerably reducing the environmental and economic costs compared with those of the conventional processes.

Characterisation of Pasting, Structural and Volatile Properties of Potato Flour

Potato flour is an important raw material for potato staple food products; nevertheless, the quality and flavor vary significantly due to process changes. In this study, the physicochemical features of fresh and five different dehydration temperature potato samples, including the degree of starch gelatinization (DG), pasting, structure properties and volatile components, were compared to investigate the effect of hot air drying (HAD) on potato flour. The results showed that the degree of pasting, viscosity and volatile aroma components changed significantly with differences in drying temperature. With the increase in drying temperature, the gelatinization degree and peak viscosity of potato powder increased or decreased, the breakdown viscosity of HAD-50 was higher, the setback viscosity of HAD-90 was higher, while the crystallization zone of HAD-90 was destroyed due to the high temperature. The flavor components of potato flour are increased during processing due to lipid oxidation, Maillard reaction and thermal degradation. The level of aldehydes,3,5-Octadien-2-one and E,E)-3,5-Octadien-2-one gradually reduced as the processing temperature increased, while the content of furans grew and then decreased, nonanal and 2-Penty-l-Furan increased. Overall, lower HAD temperatures are beneficial for the quality and flavor of potato flour. The information presented here will be useful for the further development of potato flour products.

Volatilomic fingerprinting from edible flowers. Unravelling some impact compounds behind its attractiveness

In recent years edible flowers emerged in gourmet cuisine, giving any dish the beauty of attractive colours, freshness, texture, and aromatic notes. Moreover, they also constitute a potential source of phytochemical compounds associated with beneficial effects on human health. In this work, the volatilomic fingerprinting of 4 different species of edible flowers [blue mallow (Malva sylvestris L.), pomegranate flower (Punica granatum L.), hibiscus (Hibiscus rosa-sinensis L.), and nasturtium (Tropaeolum majus L.)] used in gourmet dishes, was established, and comparatively investigated. The volatile metabolites were extracted by solid-phase microextraction in headspace mode and identified by gas chromatography-mass spectrometry to understand the chemistry behind its attractiveness better. A total of 78 volatile metabolites, belonging to diverse chemical groups were identified. Blue mallow is mainly characterised by sesquiterpenoids (61.5% of the total volatile fraction), whereas in flowers from pomegranate, hibiscus, and nasturtium, terpenoids (56.6%), carbonyl compounds (88.0%) and organosulfur compounds (98.0%) are the dominant chemical groups, respectively. In blue mallow flowers, τ-muurolene and valencene are the dominant volatiles, followed by α-cubebene and δ-cadinene. Pomegranate flowers are rich in furfural and linalool, while the aldehydes 2-hexenal, hexanal and 2-octenal are dominant volatile metabolites in hibiscus. Benzyl isothiocyanate, a potent antimicrobial agent, accounts for 98% of the total volatile fraction of nasturtium flowers. In addition to flavour notes, some of the identified volatile metabolites present bioactive properties, which could be explored for application in the food, pharmaceutical and cosmetic industries. The volatile metabolites profiles combined with unsupervised principal component analysis facilitated the differentiation of the edible flowers under investigation, revealing the most related volatile metabolites of each sample, which can be used as markers for the authentication of these valuable food samples.

Fast pyrolysis of algae model compounds for bio-oil: In-depth insights into the volatile interaction mechanisms based on DFT calculations

Fast pyrolysis of algae biomass is a promising approach to produce high value-added bio-oil, while the interaction mechanisms among the pyrolytic volatiles of algae components remain unclear. To simplify the pyrolysis process and better investigate the intermediates distribution, glucose (Glc), alanine (Ala), and glycerol (Gly) were selected as the model compounds for algae biomass. The fast pyrolysis behaviors, volatile release properties, and bio-oil compositions of model compounds and their binary mixers were performed using TG-FTIR and Py-GC/MS to reveal the volatile interaction mechanisms combined with density functional theory (DFT) calculations. Experimental results showed that co-pyrolysis of Ala with Glc and Gly displayed a synergistic effect on the weight loss and CO2 release at lower temperatures, and the volatile interactions inhibited the weight loss and CO production at higher temperatures during co-pyrolysis of model compounds. Compared with individual pyrolysis, the contents of pyrazines, furans, and pyridines in the bio-oils from co-pyrolysis of Glc+Ala, Glc+Gly, and Ala+Gly increased by 14.47%, 18.59%, and 12.07%, respectively. Ethylamine generated from Ala and small molecular aldehydes and ketones derived from Glc and Gly were the main precursors. Based on the products evolution, the possible volatile interaction pathways were proposed at the molecular level and the energy profiles were assessed by DFT calculations. Calculation results manifested that the Maillard and acetal reactions with lower free energy barriers were the initial reactions driving the formation of heterocyclic compounds. These findings could offer insights into the fast pyrolysis mechanisms of algae biomass and provide theoretical support for the feedstock and pyrolysis process optimization and the bio-oil composition regulation, thereby promoting the efficient utilization of algae.

Discovery of Novel Potential Aphid Repellents: Geranic Acid Esters Containing Substituted Aromatic Rings.

Aphids are one of the most damaging agricultural pests. For the sake of novel eco-friendly compounds with good activity for aphid control, a series of novel geranic acid esters containing substituted aromatic rings were designed by inverting ester groups of lead compounds. All compounds were characterized by HRMS, 1H-NMR, and 13C-NMR. In order to identify the effect of inversion ester groups on activity, a bioassay was conducted. The results showed that the repellent activity against Acyrthosiphon pisum (A. pisum) and the binding affinity with the odorant-binding protein 9 from A. pisum (ApisOBP9) of the compounds were increased after inversion of the ester groups. Particularly, 5f showed the best repellent activity (repellency proportion: 55.6%) and binding affinity (1/Ki: 0.49 µM). Meanwhile, the structure–activity relationships revealed that the introduction of meta-substitution of the benzene ring and halogen atoms, such as Cl and Br, facilitated the biological activity. The further molecular docking results demonstrated that hydrogen bonding interactions and hydrophobic interactions were vital for the binding affinity with ApisOBP9. Additionally, all compounds were predicted to be eco-friendly and their volatile physicochemical properties have been enhanced compared to the leads. The present results provide valuable clues for the further rational design of aphids’ behavioral control agents.

From faceted nanoparticles to nanostructured thin film by plasma-jet redox reaction of ionic gold

Cold-atmospheric plasma-assisted deposition has emerged as an efficient technique for synthesising gold nanoparticles (AuNPs). Here, a plasma-vapour interaction is used for the simultaneous reduction and deposition of AuNPs from an inorganic precursor (HAuCl4). As surface analyses suggest, plasma input power plays an important role in reduction efficiency, whereas argon gas flow rate reduction leads to the formation of smaller particles. This study demonstrates that the presence of ethanol in the reactive mixture of gold promotes improved reduction of gold to nanostructures owing to their volatile properties. A systematic investigation of plasma and the deposited nanostructures reveals that the reduction is mainly caused by the free electrons and in-situ formation of hydrogen peroxide inside plasma. Our method demonstrates that nanostructured thin film can be created within 5 min by controlling plasma parameters. Deposited AuNPs feature advanced plasmonic surface-enhanced Raman scattering responses, tested with Raman marker Rhodamine R6G, enabling their use as a potential substrate for fast and reliable optical analytical biochemical sensing.

Effect of Stable Chlorine Dioxide and Vacuum-Packing Treatments on the Physicochemical and Volatile Flavor Properties of Pike Eel (Muraenesox cinereus) during Chilled Storage.

The effects of vacuum-packaging and stable chlorine dioxide treatments on the quality of pike-eel fillets were investigated during chilled storage for a period of up to 10 days. The results reveal that the sensory scores, total volatile basic nitrogen (TVB-N) content, total viable count (TVC), malondialdehyde (MDA) content, and the myofibrillar protein (MP) content of pike-eel fillets with different packing treatments all decreased significantly over 10 days of storage. However, the vacuum-packaging and stable chlorine dioxide pretreatment showed positive effects on the protein stability of pike-eel samples. Compared with the simple packaging (SP) and vacuum packing (VP) treatments, the combination treatments (CP) significantly inhibited the rapid increases in the TVB-N content, TVC values, and MDA content. Moreover, the comparative stability in the MP and its carbonyl content were maintained. Furthermore, our volatile organic compounds (VOCs) analysis confirmed that the combined packaging treatments significantly hindered protein and lipid oxidation, inhibited the growth of spoilage bacteria, and maintained the volatile flavors of pike-eel samples during chilled storage.

Quark Cheese Processed by Dense-Phase Carbon Dioxide: Shelf-Life Evaluation and Physiochemical, Rheological, Microstructural and Volatile Properties Assessment.

Dense-phase carbon dioxide (DPCD), a novel non-thermal processing technology, has attracted extensive attention due to its excellent performance in food sterilization and enzyme inactivation without quality deterioration. In this work, we aimed to extend the shelf life of quark cheese with DPCD and explore the effect of DPCD treatment as well as storage time on the quality of quark cheese. The sterilization parameters were optimized by means of orthogonal experiments, and the physiochemical, rheological, microstructural and volatile properties of cheese were investigated. The optimal DPCD treatment (20 MPa, 45 min, 55 °C) successfully extended the shelf life of quark cheese due to its inhibition effect on yeast and was able to slow down the proteolysis and alterations in pH and color of cheese. Cheese processed using DPCD after 14-day storage even displayed similar rheological properties to the control at day 0, from which bound water significantly migrated during storage. Moreover, DPCD contributed to the retention of the volatile profile of cheese during storage. This study demonstrated that DPCD is a promising pasteurization technology for quark cheese to improve its quality stability during storage.

Characterization of indigenous coagulase-negative staphylococci isolated from Chinese spontaneously fermented meat products

Technological, safety-related and volatile properties were analyzed in coagulase-negative staphylococci (CNS) isolates from Chinese spontaneously fermented meat products. A total of 107 CNS isolates were identified via 16 S rRNA sequencing, and the most recovered species were S. saprophyticus (53.3 %), S. edaphicus (12.1 %), and S. epidermidis (10.3 %). Among them, 58 CNS isolates belonging to 9 species were selected with higher activities of catalase, nitrate reductase, proteolysis, and lipolysis, as well as higher tolerance to stressful environmental conditions. Then, 7 CNS isolates belonging to 4 species were further selected based upon excellent technological characteristics, lack of hemolysis and antibiotic resistance, and a low production of biogenic amines. The volatile profiles of these 7 strains cultivated in pork broth was determined. S. casei No. 1 produced significant amounts of phenethyl alcohol, geraniol, and 3-methyl-butanol. S. xylosus No. 120 produced the highest amount of methyl ketones with the potential to provide dry-cured odor of fermented meats. The volatile profile was highly strain dependent. Several CNS identified in this study have the potential to be used as the starter cultures for fermented meat products.

The impact of pasture and non-pasture diets on the sensory and volatile properties of whole milk powder.

This study evaluated the impact of three distinct diets; perennial ryegrass (GRS), perennial ryegrass/white clover (CLV) and total mixed ration (TMR), on the sensory properties and volatile profile of whole milk powder (WMP). The samples were evaluated using a hedonic sensory acceptance test (n = 99 consumers) and by optimised descriptive profiling (ODP) using trained assessors (n = 33). Volatile profiling was achieved by gas chromatography mass spectrometry using three different extraction techniques; headspace solid phase micro-extraction, thermal desorption and high capacity sorptive extraction. Significant differences were evident in both sensory perception and the volatile profiles of the WMP based on the diet, with WMP from GRS and CLV more similar than WMP from TMR. Consumers scored WMP from CLV diets highest for overall acceptability, flavour and quality, and WMP from TMR diets highest for cooked flavour and aftertaste. ODP analysis found that WMP from TMR diets had greater caramelised flavour, sweet aroma and sweet taste, and that WMP from GRS diets had greater cooked aroma and cooked flavour, with WMP derived from CLV diets having greater scores for liking of colour and creamy aroma. Sixty four VOCs were identified, twenty six were found to vary significantly based on diet and seventeen of these were derived from fatty acids; lactones, alcohols, aldehydes, ketones and esters. The abundance of δ-decalactone and δ-dodecalactone was very high in WMP derived from CLV and GRS diets as was γ-dodecalactone derived from a TMR diet. These lactones appeared to influence sweet, creamy, and caramelised attributes in the resultant WMP samples. The differences in these VOC derived from lipids due to diet are probably further exacerbated by the thermal treatments used in WMP manufacture.