Odorous Substances Research Articles

Enhancing protein-based foam stability by xanthan gum and alkyl glycosides for the reduction of odor emissions from polluted soils

Odorous contamination would occur in the polluted soils' remediation of the abandoned industry factory. To suppress odorous substances’ emissions, a novel foam was prepared with plant protein, xanthan gum, and alkyl glycosides. Since xanthan gum and alkyl glycosides have the characteristics of prolonged foam half-life and enhanced foaming ability, the optimal ratio of xanthan gum to alkyl glycosides is crucial during foam formulation determination. When xanthan gum concentration increased from 0.00% to 0.30%, the viscosity of the foaming solution increased from 12 to 223 mPa∙s, while the surface tension declined by 12.3%. As a result, the foam half-life increased from 0.3 to 56 h, and the foaming volume decreased by 25.5%. On contrary, with the addition of alkyl glycosides, the surface tension decreased significantly, and the foaming volume increased by 36.5% under the xanthan gum concentration of 0.30%. Therefore, the optimal content of xanthan was 0.30% in the presence of 100 mM alkyl glycoside. Then, this novel foam could prevent 67% of p-xylene from escaping within 24 h. In actual sites, novel foams showed a barrier rate of over 75% on different odorous substances most of the time.

Emission Characteristics and Risk Assessment of Gas Pollutants in Typical Pesticide Manufacturing Enterprises

In order to explore the characteristics of exhaust gas emissions, environmental impact, and human health risks in the pesticide manufacturing industry, two typical pesticide manufacturing enterprises were selected as the research objects, and samples were collected and analyzed for all exhaust pipes of each enterprise. The following results were noted:there were certain differences in the pollutants produced by different enterprises due to different products and production links. The main pollutants in enterprise A were ammonia and VOCs. The concentration of ammonia in enterprise A ranged from 0 to 847.83 mg·m-3, and the concentration of VOCs ranged from 4.21 to 91.68 mg·m-3. The main pollutants in enterprise B were VOCs, and the concentration of VOCs ranged from 3.37 to 197.30 mg·m-3. The ozone formation potential (OFP) ranged from 1.96 to 107.24 mg·m-3. Substances that required further attention in terms of ozone formation potential:enterprise A mainly included ethanol, methanol, toluene, xylene, and other substances; enterprise B mainly included 1, 1-dichloroethylene, 1, 2-dichloroethane, toluene, methylal, and other substances. The secondary organic aerosol formation potential (SOAFP) ranged from 0.94 to 74.72 mg·m-3. The main contributors to the secondary organic aerosol formation potential were aromatic hydrocarbons and oxygen-containing organics. In addition, ammonia also required additional attention. The odorous substances in pesticide enterprises were more complex, and there were differences in the exhaust pipes of different enterprises and different production links of the same enterprise. There were certain health risks in the gas pollutants of pesticide enterprises. The main carcinogens were 1, 2-dichloroethane, trichloroethylene, tetrachloroethylene, methyl chloride, and benzene. In addition, pyridine and hexachloroethane had certain non-carcinogenic risks in pesticide production enterprises.

Using novel DNA methods to achieve higher process efficiency and performance

Uncontrolled microbiological activity is a challenge for recycled fiber (RCF) mills as it can have negative effects on production and end-product quality. The microbes that exist in these systems have been largely unknown, and the strategies employed to control microbiology have been non-specific. Understanding the specific microbial groups present in RCF mills, their properties, and where they exist, as well as having the ability to accurately measure the true troublemakers, are key to targeted control of the bad actors. In this study, we present the results of a global survey of over 40 RCF paper machines. The same RCF-specific problem-causing bacterial groups were found on different continents, including large densities of newly identified bacteria in paper processes. Those can degrade cellulose and starch, produce acids and odorous substances, and have a significant impact on fiber strength and additive consumption. We also demonstrate how modern DNA tools can quantify the impact of biocidal countermeasures against the actual troublemakers, including bacteria found to degrade cellulose during RCF pulp storage, which may be linked to a negative impact on end-product strength. These novel DNA tools give producers updated biocide program key performance indicators (KPIs) and actionable information to more effectively design and adjust microbiological control to achieve higher process efficiency and performance.

Anti‐parasitic function of tree‐rubbing behaviour in brown bears suggested by an in vitro test on a generalist ectoparasite

AbstractRubbing against various objects or self‐anointing with pungent substances are behaviours observed in many mammal species. The brown bear (Ursus arctos) is a non‐territorial species that rubs against trees with the main purpose being intraspecific communication. In addition, some odorous substances are known for eliciting rubbing behaviour and hence are used to lure bears to trees in studies relying on non‐invasive hair collection. Tree‐rubbing is often accompanied by clawing and debarking which release tree resin that impregnates the fur and can potentially deter ectoparasites. Here, we present a study aiming to determine whether ticks, being widely spread and an important vector of pathogens, are repelled by resin products known to attract bears and elicit rubbing behaviour, namely turpentine and beech tar. Dermacentor reticulatus ticks were offered a binary microhabitat choice by placing them in the middle of individual horizontal tubes with tested substances placed on filter paper at one end, and distilled water as a control (neutral) substance at the other. Their behaviour was recorded for three minutes. Ticks consistently touched the neutral end of the tube while avoiding treated ones. Overall, ticks remained at greater distances from treatments than from water. A fitted logarithmic regression showed ticks did not spend more than seconds at a treated side, supporting our prediction that ticks are repelled by turpentine and beech tar. Parasite repellency may bring a further advantage in rubbing behaviour trade‐offs, compensating some energetical costs, and adds a trait to the behaviour important in seemingly divergent contexts of intraspecific communication and defense against ectoparasites.

Effect of different odors on the fighting behavior of weaning piglets after merging into a large pen.

In intensive pig production, the fighting behavior of weaning piglets after merging pens is relatively common. Fighting behavior not only easily causes injury in pigs but also affects the production performance of pigs. To reduce fighting behavior in farms, this study aimed to explore the possible effect of odorous substances on piglet fighting behavior after merging into a large pen. Six different sprays were tested: original creamy, cheese flavor, orange flavor, truffle, vanilla and pigpen flavor. In each experiment, two groups were set (one odor-sprayed and no sprayed control), and 12 pigs were used per group. After mixing, the frequency of occurrence of various piglet behaviors in different pens was recorded. During this period, salivary cortisol levels and skin lesion scores were evaluated. As a result, the piglets sprayed with the original creamy, cheese flavor and vanilla substances obtained significantly higher average daily gain and feed intake and showed a significantly lower incidence of fighting behavior, and the skin lesion score and salivary cortisol of piglets were also reduced significantly. All the other odorous substances had no significant effects on the fighting behavior and production performance of piglets.

The mechanism of spoilage of a bottled soft drink leading to health problem of consumer.

The case of spoilage of flavoured and sweetened soft drink occurred in the Czech Republic in 2019. After drinking it, the consumer was admitted to a hospital with sickness. The spoilage was caused by mould and an odorous substance, 1,3-pentadiene. The mechanism of food spoilage, with the formation of 1,3-pentadiene arising from the decarboxylation of sorbic acid and mould growth, is described. This could be the second case history reported worldwide of an allergic reaction to penicillin explaining how penicillin might get into the beverage. We hypothesise three possible causes of the health problem experienced with allergic reaction to penicillin or other mycotoxin produced by Penicillium mould as the most probable one.

Comparison of the performance of German Shepherds and Belgian Shepherd Malinois in scent detection tests

Detection dogs trained to search for various odorous substances are an effective tool in the fight against crime. Due to the high costs of training and maintaining these dogs, it is necessary to preselect suitable individuals for this purpose. One of the selection criteria is the dog breed. Unfortunately, there is a lack of studies that compare dog breeds for their suitability as detection dogs. Until the recent past, German Shepherds were widely used by police, army and customs services around the world. However, over the last few decades, Belgian Shepherd Malinois have become more popular in terms of service cynology.The aim of our study was to compare the two most common working dog breeds, namely the German Shepherd and Belgian Shepherd Malinois (Malinois). The prediction was made that Malinois would not outperform German Shepherds. For this purpose, we evaluated the results of customs dogs (539 German Shepherds and 177 Malinois) currently undergoing their certification process against data from a 10-year database.The certification process consists of two sets of tests: scent detection and obedience. Every scent detection dog was required to search for specific target scents (drugs, banknotes and tobacco) in six training areas that imitated real workplaces. The obedience test consisted of ten tasks, which the dog had to perform (e.g. recall, heelwork, changes of position at the handler's leg). The evaluation of the scent detection and obedience tests was done by certified judges. The data were analysed using PROC GLIMMIX in SAS software (version 9.4). The results of the scent tests did not reveal a significant difference between the breeds (P = 0.31) For the obedience test, the scores were higher in Malinois (84%) compared to German Shepherds (80%), with P < 0.01. The age and sex of the dogs did not significantly affect their evaluation in both tests. Our results showed that although Malinois do not outperform German Shepherds in the special discipline - the detection of specific target scents - both breeds are suitable for this purpose.

Prediction of Complex Odor from Pig Barn Using Machine Learning and Identifying the Influence of Variables Using Explainable Artificial Intelligence

Odor is a very serious problem worldwide. Thus, odor prediction research has been conducted consistently to help prevent odor. Odor substances that are complex odors are known, but complex odors and odor substances do not have a linear dependence. In addition, depending on the combination of odor substances, the causal relationships, such as synergy and antagonism, are different for complex odors. Research is needed to know this, but the situation is incomplete. Therefore, in this study, research was conducted through data-based research. The complex odor was predicted using various machine learning methods, and the effect of odor substances on the complex odor was verified using an explainable artificial intelligence method. In this study, according to the Malodor Prevention Act in Korea, complex odors are divided into two categories: acceptable and unacceptable. Analysis of variance and correlation analysis were used to determine the relationships between variables. Six machine learning methods (k-nearest neighbor, support vector classification, random forest, extremely randomized tree, eXtreme gradient boosting, and light gradient boosting machine) were used as predictive classification models, and the best predictive method was chosen using various evaluation metrics. As a result, the support vector machine that performed best in five out of six evaluation metrics was selected as the best model (f1-score = 0.7722, accuracy = 0.8101, sensitivity = 0.7372, specificity = 0.8656, positive predictive value = 0.8196, and negative predictive value = 0.8049). In addition, the partial dependence plot method from explainable artificial intelligence was used to understand the influence and interaction effects of odor substances.

UV/H2O2/O3 removal efficiency and characterization of algae-derived organic matter and odorous substances

Algal organic matter (AOM) released from the metabolic processes of alga is an important source/precursor for toxic substances, thus it has aroused major environmental concerns due to its threat to safe water supplies. In this study, the algae Anabaena was selected as the target species, and a UV/H2O2/O3 advanced oxidation process (AOP) was used for AOM degradation. Overall, the intracellular organic matter (IOM) of Anabaena was mainly composed of soluble microbial metabolites, tyrosin and tryptophan, while the extracellular organic matter (EOM) mainly contained fulvic-acid and humic-acid substances, soluble microbial metabolites. The AOM mainly contained odorous substances such as cyclocitral, ionone, isophorone and a small amount of geosmin (GSM). Low molecular weight and hydrophobic components produced the highest formation potential of trihalomethane (THMFP) and dichloroacetonitrile (DCANFP). The Trichloromethane formation potential (TCMFP) of the different molecular weight (MW) components was higher than the standard for drinking water (> 60 μg/L), while the cytotoxicity of DCANFP was much higher than that of THMFP. The degradation efficiency of the UV/H2O2/O3 technology for cyclocitral was significant, but it could not effectively reduce the TCMFP and DCANFP. After treatment with UV/H2O2/O3, the EEM intensity of organic matter in each area decreased, and the biodegradability of AOM improved.

International experience of air pollution assessment in areas where enterprises with odorous emissions are located (literature review)

The article provides a review of literature data on approaches to the ambient air pollution assessment in the areas where enterprises - sources of odour are located. According to the analysis, international practice in the field of odour management in the atmosphere includes a variety of methods of the odour impact assessing. The considered approaches, both predictive and observational (empirical), have their advantages and disadvantages. Thus, atmospheric dispersion modelling is a very valuable predictive tool and plays an important role in assessing ambient odours. However, the models, although based on rigorous quantitative calculations, are a simplification of the real situation. The accuracy of this method is significantly reduced in cases of unpredictable, unplanned or accidental releases. An easier-to-use tool is a qualitative (descriptive) risk-based odour assessment (source-pathway-receptor concept). Empirical approaches (field olfactometry, sniff tests) make it possible to assess odour exposure in given real conditions, while more objective assessment requires long-term studies. The use of instrumental methods is limited by the fact that odours in the air are mainly due to complex multicomponent mixtures of substances with an unknown nature of the combined action, with levels below the detection limits, etc. When developing an odour assessment strategy, it is necessary to select the tools that are most appropriate in each case. According to many authors, to improve the quality and reliability of this assessment in areas where enterprises and other facilities are located, it is advisable to use all available empirical approaches together with modelling, in combination with community surveys and other methods of analyzing the health status of the population. The data obtained as a result of such a comprehensive assessment will make it possible to substantiate measures to reduce air pollution by odorous substances. The literature search was carried out in the English-language text databases PubMed, Scopus, Web of Science and in the scientific electronic library eLIBRARY.ru. (RSCI)

A preliminary evaluation on mixed probiotics as an antimicrobial spraying agent in growing pig barn

The purpose of this study is to examine whether spraying an anti-microbial agent into the slurry pit will reduce the noxious odor substances from piggery barns. For this, a total of 200 crossbred ([Landrace × Yorkshire] × Duroc) growing pigs with an initial average body weight (BW) of 23.58 ± 1.47 kg were selected and housed in two different rooms, i.e. control (CON) and treatment (TRT). Each room has 100 pigs (60 gilts and 40 borrows). For a period of 42 days, all pigs were fed with corn-soybean meal-based basal diet. Later the noxious odor substances were measured by the following methods. First, fecal samples were randomly collected and stored in sealed and unsealed containers, and sprayed with the non-anti-microbial agent (NAMA) (saline water) and multi-bacterial spraying (MBS) agent (200 :1, mixing ratio-fecal sample : probiotic), Second, the slurry pit of CON and TRT rooms were directly sprayed with NAMA and MBS, respectively. The fecal sample that was stored in sealed and un-sealed containers and sprayed with MBS significantly reduced NH3 and CO2 concentration at the end of day 7. However, at the end of day 42, the fecal sample showed a lower H2S, methyl mercaptans, acetic acid, and CO2 concentration compared to the unsealed container. Moreover, at the end of days 7, 14, 21, 28, 35, and 42 compared to the CON room and TRT room slurry pit emits lower concentrations of NH3, acetic acid, H2S, and methyl mercaptans, and CO2 into the atmosphere. Based on the current findings, we infer that spraying anti-microbial agents on pig dung would be one of the better approaches to suppress the odor emission from the barn in the future.

Evaluation of the Barrier Effect of Polylactic Acid-Modified Membrane on Odours at the Excavated Soil Interface of a Pesticide-Contaminated Site

Polylactic acid (PLA) is a highly promising bio-based polymer that can replace petroleum-based materials. The PLA-modified membrane has been found to effectively block soil odours in laboratory experiments, but its barrier effect at the excavated soil interfaces of actual pesticide sites requires further evaluation. This study investigates the barrier effect of the PLA-modified membrane on odours at the excavated soil interface of a pesticide-contaminated site in Guangdong Province, China. The membrane’s barrier effect on odours was comprehensively evaluated using the static chamber technique with three indicators: diffusion flux, odour concentration, and a health risk index. The results showed that the initial diffusion fluxes of six main odour substances: m- and p-xylene, o-xylene, toluene, ethylbenzene, n-propylbenzene, and cumene were 1.95 × 100, 2.88 × 10−1, 7.27 × 10−3, 1.49 × 100, 2.97 × 10−3, and 3.89 × 10−3 mg/(m2·s) based on the contribution rate. After laying the PLA-modified membrane, the flux reduction rate of all six odour substances was generally &gt;90%. The background odour concentration in the test area was 109.56, and the odour concentration after laying the membrane was &lt;1.12. The initial non-carcinogenic and carcinogenic risk indices of the test area were 3.03 and 1.62 × 10−4, respectively. After laying the membrane, these indices were &lt;0.05 and &lt;3.78 × 10−7, respectively, indicating no health risk. Overall, the PLA-modified membrane had a good barrier effect on odours in the on-site application, effectively reducing the diffusion and nuisances of odours, as well as their health risks.

Investigation of odor emissions from coating products: Key factors and key odorants

Coating products are widely used for the interior decoration of residential property. However, there is growing concern regarding their odor emissions and their impact on indoor air quality (IAQ). Most manufacturers and government agencies set odor intensity limits to control the odor of coating products, including their raw materials. However, it is difficult to determine product performance by means of their odor intensity index. Although evaluating odor intensity requires odor assessors to distinguish between different intensity levels, low consensus and reproducibility represent challenges that are difficult to avoid. As the odor concentration index only requires odor assessors to ascertain whether the odor is felt or not, the reproducibility of the evaluation results is relatively better. Moreover, suitable methodologies for determining odor concentrations in volatile coating product emissions have rarely been reported. Therefore, establishing an evaluation method for odor concentration of coating products and exploring its key influencing factors should bridge this gap. We examined the influence of the airbag material on the recovery rate of typical volatile organic compounds (VOCs) using direct injection by GC-MS and established that their adsorption effects were in the order: PET &amp;gt; PVF &amp;gt; PTFE. We then explored the influences of the sample curing and odor emission times on odor concentration. The solvent-based and water-based coatings reached equilibrium after 8 h and 16 h curing, respectively, and after 8 h and 12 h odor emission, respectively. The odor concentrations of real coating samples were measured and compared against their odor intensities. The odor concentration method more accurately and reliably discriminated coating products than the odor intensity approach. Thus, to assist manufacturers in improving coating formulations to reduce the odor impact of coating products, we used headspace gas chromatography to determine the odor substances in water- and solvent-based coatings and analyzed the odor contribution of various volatile compounds using the odor activity value (OAV) method. Butyl acetate, ethylbenzene, and 1-methoxy-2-propyl acetate were the key odorants in solvent-based coatings while 1-butanol, ethylbenzene, and butyl acetate were the key odorants in water-based coatings.

Пути использования дикорастущих пищевых растений Приморского края (Российская Федерация)

In the flora of Primorye Territory, there are 374 species of wild edible plants from 249 genera and 93 families. Vegetative parts are mainly used for food production: leaves (193 species), shoots (102 species), stems (49 species), rhizomes (46 species), roots (24 species) and bulbs (14 species). Generative parts are used less often: fruits and seedlings (84 species), flowers (44 species), seeds (43 species). Quite rarely, buds (9 species), tubers (8 species), root cones (4 species), etc. are used. From the point of view of the timing of the collection of plant food raw materials, species collected in spring (198 species) and in summer (176 species) predominate and autumn (167 species). During the growing season, 26 species can be used, and 3 species can be used throughout the year. There are many ways to use wild food plants. Most species (about 250) are used as vegetable plants - fresh, like spring greens, for salads and soups. A lot of plants are used to obtain drinks (about 100 species), 56 species each have value as fruit plants (preparation of jam, jelly, jams, etc.) and starch plants (from which flour is obtained for addition to wheat flour). Least of all oilseeds, plants, as well as plants used for conservation and curdling of milk. Fruit plants, spring vegetables (111 species in total) can be used fresh, others need to be processed (most often thermal) before use to remove toxic and odorous substances. Keywords: WILD FLORA, FOOD PLANTS, COLLECTION TIME, WAYS OF USE, PRIMORYE TERRITORY

Colorimetric Array Electronic Nose for Automotive Interior Material Odor Detection

This study aims to detect the odor intensity levels of automotive adhesive tapes accurately, efficiently, and non-destructively. A 35-array colorimetric sensing test paper was developed using a polyvinylidene fluoride (PVDF) laminated test paper as the substrate and an acid-base solvent to detect the odor substances volatilized from the automotive interior materials. Detection experiments results show that the main odor substances volatilized from the automotive tape samples were aldehydes, ketones, acids, and ethers, changing colors at the relevant spots of the corresponding test paper. Hierarchical clustering analysis (HCA), principal component analysis (PCA), and partial least squares regression (PLSR) show that the colorimetric array test paper could accurately identify the different odor intensities of the automotive tape samples. To test the detection level of the colorimetric electronic nose on the odor intensity of other automotive tapes, a separate automotive tape sample prediction utilizes the electronic nose. All predicted odor intensity values of the separate automotive tape sample deviated by less than 0.4 from the subjective evaluation results and by less than 0.5 from the subjective evaluation results. Thus, the objective prediction model based on the colorimetric electronic nose can be used for detecting automotive adhesive tapes with different odor intensities.

The Important Elements in the Formation of Odorous Substances in Black Odorous Water

At present, black odorous water is an important issue in waste water management, as it seriously affects the quality of river and lake water. However, how black odorous water forms still remains largely unclear. Under the conditions of artificially simulating black and odorous water bodies, the formation conditions, generation mechanism and forming process of odorous substances-H2S were researched by adding different basic substances, including sulfur-containing substances, inorganic salts, and metal ions. The results showed that there must be sulfur-containing substances to induce a black bloom in 5–9 d, and that the Oxidation-Reduction Potential (ORP) should be less than −200 mv, an optimal condition for forming black odorous water. Cysteine was the primary precursor for the production of H2S. Furthermore, when the inorganic nitrogen salt additions were &gt;10 mg/L, the formation of H2S was inhibited. Finally, metal ions inhibit the degree of odor-causing in water was Cu2+ &gt; Fe2+ &gt; Mn2+. The microbial communities were also monitored during the development of the black odorous and the predominant bacteria were proteobacteria and it showed that the proteobacteria could desulfurize high-valence organic compounds containing sulfur become low-valence simple sulfides.

Odorants in the organophosphorus pesticide contaminated soils：identification, prioritization, and quantification using GC-HRMS based on target and non-target screening

Odorants from the pesticide site remediation were complex and changeable, and the screening of key odorous substances was the prerequisite for the process of odor control. In the study, a novel odorants identification method based on the targeted and non-targeted approach by gas chromatography-quadrupole/electrostatic field orbitrap high-resolution mass spectrometer (GC Orbitrap/MS) was established to investigate the low-concentration odor pollution in three organophosphorus pesticide sites. The comprehensive odor characterization method was developed and applied in the light of olfactory threshold, flavor characteristics, molecular structure, response value, and detection rate. 98 pollutants were screened out using target analysis, and 149 substances were identified with confidence levels of at least 2 based on non-target analysis. Based on the analysis results, 42 odorants were screened out by the synthetic evaluation method for priority control, including phenols, aldehydes, ketones, esters, organic sulfide, amines, nitriles, amide, acylchlorides, ethers, heterocyclic, halogenated benzene and polycyclic aromatic hydrocarbons. The limit of detection (LOD) of 42 odorants was from 0.010 to 0.100 ng L−1, which was lower than other detection methods. This research provided a new technology for identification of odorants in pesticide sites.

Temporal and Spatial Variation in Odor Pollution and Membrane Barrier Effect in Municipal Solid Waste Landfill

In order to explore the source characteristics as well as the temporal and spatial variations in odor pollution in municipal waste landfills, gas samples were collected from a landfill in an eastern coastal area of China throughout winter and summer. The total concentration of malodorous substances reached 60000 μg·m-3. There were more types of odor pollutants detected in summer than in winter, the average concentration was 30-300 times higher than that in winter, and the concentration of sulfur compounds increased by 4.7-136.7 times in summer. Oxygenated compounds had the highest concentration, and the total concentration of sulfur compounds accounted for less than 10% of malodorous substances. However, sulfur compounds contributed more than 90% to the theoretical odor concentration. Sulfur compounds such as methyl mercaptan and propane mercaptan were the key odorants in the landfill. After the landfill unit was covered, the concentration of odorous substances and the theoretical odor concentration on the surface of the landfill showed an increasing trend with time, indicating that the covering had a certain odor barrier effect; however, the landfill unit still had a large odor release potential. The similarity analysis showed that the odorous gas accumulated in the unit with temporary cover and without an exhaust system could be released to the environment through the overlapping gap of the membrane and the location of membrane rupture, resulting in more serious odor pollution around the landfill at night than that during the day.

The Development of Anammox and Chloroflexi Bacteria during the Composting of Sewage Sludge

The C/N ratio is an extremely important parameter in the composting process and is directly responsible for the growth of microorganisms. A low C/N ratio contributes to higher emissions of greenhouse gases and odorous substances, such as ammonia (NH3), which is formed by nitrogen mineralization. Due to the highly toxic effects of ammonia, it is a particularly unwanted by-product that can disrupt the composting process since it poisons microorganisms and causes environmental issues. The activity of anammox bacteria, so far analyzed only in wastewater treatment processes, is a particularly efficient method of nitrogen removal, having an advantage over the conventional methods used previously. This study shows the presence of anammox bacteria during composting, which allows for an opportunity to improve the process and reduce its impact on atmospheric pollution. Despite the aerobic nature of this process, the composted mass of waste presents conditions conducive to the development of these ammonia-oxidizing bacteria, as well as the other strains of microorganisms cooperating with them. This makes it possible to compost at a low C/N ratio; in addition, there is no need for an additional energy supply through aeration, as the processes carried out by anammox bacteria do not require oxygen. Therefore, more in-depth research is necessary to evaluate the low C/N effect on anammox and Chloroflexi bacteria growth and its effect on nitrogen balance during composting.

Insight into the Influence of Lactic Acid Bacteria Fermentation on the Variations in Flavor of Chickpea Milk.

This study aimed to evaluate the influence of fermentation on the levels of free amino acids (FAAs) and variations of volatile odorants in four groups of chickpea milk. Electronic nose (E-nose) and gas chromatography–mass spectrometry (GC-MS) data were subjected to mutual validation. W2S and W3S sensors of E-nose were sensitive to volatile constituents in the four groups of unfermented and fermented specimens. After fermentation, the levels of FAAs in the four groups of specimens decreased to varying degrees. Additionally, there were remarkable differences in the types and contents of volatile odor substances in all specimens before and after fermentation. The principal component analysis findings based on E-nose identified the changes of volatile odorants in all specimens before and after fermentation. GC-MS identified 35 and 55 volatile flavor substances in unfermented and fermented specimens, respectively. The varieties of volatile odor substances in fermented chickpea milk (FCM) with papain treatment plus yam addition (38) were more than those in FCM (24), indicating that the coupled treatment of enzymolysis and yam addition could enrich the volatile odorants in fermented specimens. After probiotic fermentation, the contents of off-flavor substances decreased to a certain extent, and key aroma substances such as 2,3-pentanedione, 2,3-butanedione, and heptyl formate were detected. These results demonstrated that lactic acid bacterial fermentation on the basis of enzymolysis and yam addition could be utilized as a feasible approach to improve the flavor of plant-based products adopting chickpea as the original ingredient.