MOGAT: A Multi-Omics Integration Framework Using Graph Attention Networks for Cancer Subtype Prediction.

Accurate cancer subtype prediction is crucial for personalized medicine. Integrating multi-omics data represents a viable approach to comprehending the intricate pathophysiology of complex diseases like cancer. Conventional machine learning techniques are not ideal for analyzing the complex interrelationships among different categories of omics data. Numerous models have been suggested using graph-based learning to uncover veiled representations and network formations unique to distinct types of omics data to heighten predictions regarding cancers and characterize patients' profiles, amongst other applications aimed at improving disease management in medical research. The existing graph-based state-of-the-art multi-omics integration approaches for cancer subtype prediction, MOGONET, and SUPREME, use a graph convolutional network (GCN), which fails to consider the level of importance of neighboring nodes on a particular node. To address this gap, we hypothesize that paying attention to each neighbor or providing appropriate weights to neighbors based on their importance might improve the cancer subtype prediction. The natural choice to determine the importance of each neighbor of a node in a graph is to explore the graph attention network (GAT). Here, we propose MOGAT, a novel multi-omics integration approach, leveraging GAT models that incorporate graph-based learning with an attention mechanism. MOGAT utilizes a multi-head attention mechanism to extract appropriate information for a specific sample by assigning unique attention coefficients to neighboring samples. Based on our knowledge, our group is the first to explore GAT in multi-omics integration for cancer subtype prediction. To evaluate the performance of MOGAT in predicting cancer subtypes, we explored two sets of breast cancer data from TCGA and METABRIC. Our proposed approach, MOGAT, outperforms MOGONET by 32% to 46% and SUPREME by 2% to 16% in cancer subtype prediction in different scenarios, supporting our hypothesis. Our results also showed that GAT embeddings provide a better prognosis in differentiating the high-risk group from the low-risk group than raw features.

Towards Inductive and Efficient Explanations for Graph Neural Networks.

Despite recent progress in Graph Neural Networks (GNNs), explaining predictions made by GNNs remains a challenging and nascent problem. The leading method mainly considers the local explanations, i.e., important subgraph structure and node features, to interpret why a GNN model makes the prediction for a single instance, e.g. a node or a graph. As a result, the explanation generated is painstakingly customized at the instance level. The unique explanation interpreting each instance independently is not sufficient to provide a global understanding of the learned GNN model, leading to the lack of generalizability and hindering it from being used in the inductive setting. Besides, training the explanation model explaining for each instance is time-consuming for large-scale real-life datasets. In this study, we address these key challenges and propose PGExplainer, a parameterized explainer for GNNs. PGExplainer adopts a deep neural network to parameterize the generation process of explanations, which renders PGExplainer a natural approach to multi-instance explanations. Compared to the existing work, PGExplainer has better generalization ability and can be utilized in an inductive setting without training the model for new instances. Thus, PGExplainer is much more efficient than the leading method with significant speed-up. In addition, the explanation networks can also be utilized as a regularizer to improve the generalization power of existing GNNs when jointly trained with downstream tasks. Experiments on both synthetic and real-life datasets show highly competitive performance with up to 24.7% relative improvement in AUC on explaining graph classification over the leading baseline.

Effects of different stress conditions on the production, bioactivities, physicochemical and structural characteristics of exopolysaccharides synthetized by Schleiferilactobacillus harbinensis Z171.

This study systematically investigated the effects of stress conditions including temperature, pH, H2O2, NaCl, antibiotics on the production and in vitro cholesterol-lowering activity of the exopolysaccharide (EPS) synthetized by Schleiferilactobacillus harbinensis Z171. Additionally, the influences of the optimal stress condition combined with different carbon sources on EPS production were examined, shedding light on the structural characteristics, physicochemical properties and bioactivities of EPSs. The results demonstrated that the EPS produced under H2O2 stress was optimal and presented excellent resistance to simulated gastric juice and α-amylase. Three main fractions, denoted as G-EPS1, F-EPS1 and S-EPS1, were isolated by cellulose DEAE-52 chromatography from crude EPSs synthetized using glucose, fructose and sucrose as carbon sources, respectively. Among them, F-EPS1 possessed the highest cholesterol-lowering, antioxidant and hypoglycemic activities, with the highest molecular weight 91.03 kDa, largest particle size 40.14 nm and apparent viscosity 288.2 mPa·s. Three EPSs exhibited irregular sheet-like and granular structures with good thermal stability. Structural characterization of F-EPS1a (a purified fraction from F-EPS1) revealed that it was a mannan mainly composed of →2)-α-D-Manp-(1→, →3)-α-Manp-(1→ and →2,6)-α-D-Manp-(1→ with branch chains containing α-D-Manp-(1→. F-EPS1a has more potential to be a natural cholesterol-lowering, hypoglycemic and antioxidant supplements in the food industry.

Ecological factors associated with child sexual abuse among 15- to 17-year-old adolescents in mainland China: implications for intervention.

Background: Child sexual abuse is a major public health problem with adverse consequences for victims' physical, mental, and reproductive health. This cross-sectional study aimed to determine the prevalence of child sexual abuse and its associated factors among 15- to 17-year-old adolescents in mainland China. Methods: From September 8, 2019 to January 17, 2020, a total of 48,660 participants were recruited by 58 colleges and universities across the whole country to complete the self-administered, structured, online questionnaire. This analysis was restricted to 3,215 adolescents aged between 15 and 17 years in mainland China. Chi-square tests and multivariate Logistic regression analyses were performed to identify individual, relationship, and community factors associated with child sexual abuse. Results: The overall prevalence of child sexual abuse was 12.0%. More specifically, 13.0% of girls and 10.6% of boys reported that they were sexually abused prior to 18 years of age. At the individual level, being female, sexual minority identity, younger age, and higher levels of knowledge, skills and self-efficacy regarding condom use were significantly related to increased odds of reporting sexual abuse. At the relationship and community level, adolescents from disrupted families and those entering into a marriage, having casual sexual partners, and having first intercourse at a younger age were more likely to report sexual abuse. On the contrary, those who had never discussed sex-related topics with their family members at home and were offered school-based sexuality education later (vs. earlier) were less likely to report sexual abuse. Conclusion: Multilevel prevention programs and strategies, including targeting adolescents with high-risk characteristics, educating young children and their parents about child sexual abuse prevention and optimizing the involvement of parents, school, community, society and government in comprehensive sexuality education, should be taken to reduce child sexual abuse among 15- to 17-year-old adolescents.

A bat MERS-like coronavirus circulates in pangolins and utilizes human DPP4 and host proteases for cell entry.

It is unknown whether pangolins, the most trafficked mammals, play a role in the zoonotic transmission of bat coronaviruses. We report the circulation of a novel MERS-like coronavirus in Malayan pangolins, named Manis javanica HKU4-related coronavirus (MjHKU4r-CoV). Among 86 animals, four tested positive by pan-CoV PCR, and seven tested seropositive (11 and 12.8%). Four nearly identical (99.9%) genome sequences were obtained, and one virus was isolated (MjHKU4r-CoV-1). This virus utilizes human dipeptidyl peptidase-4 (hDPP4) as a receptor and host proteases for cell infection, which is enhanced by a furin cleavage site that is absent in all known bat HKU4r-CoVs. The MjHKU4r-CoV-1 spike shows higher binding affinity for hDPP4, and MjHKU4r-CoV-1 has a wider host range than bat HKU4-CoV. MjHKU4r-CoV-1 is infectious and pathogenic in human airways and intestinal organs and in hDPP4-transgenic mice. Our study highlights the importance of pangolins as reservoir hosts of coronaviruses poised for human disease emergence.

Antibiofilm and Antiquorum Sensing Potential of Lactiplantibacillus plantarum Z057 against Vibrio parahaemolyticus.

Vibrio parahaemolyticus is a widespread foodborne pathogen that causes serious seafood-borne gastrointestinal infections. Biofilm and quorum sensing (QS) are critical in regulating these infections. In this study, first, the ability of Lactiplantibacillus plantarum Z057 to compete, exclude, and displace V. parahaemolyticus biofilm was evaluated. Then, the inhibitory effects of L. plantarum Z057 extract (Z057-E) on V. parahaemolyticus biofilm and QS were explored from the aspects of biofilm biomass, metabolic activity, physicochemical properties, extracellular polymer matrix content, QS signal AI-2 activity, biofilm microstructure, and the expression levels of biofilm and QS-related genes. Results showed that L. plantarum Z057 effectively inhibited biofilm formation of V. parahaemolyticus and interfered with the adhesion of V. parahaemolyticus on the carrier surface. In addition, the Z057-E could significantly reduce the biofilm biomass, metabolic activity, hydrophobicity, auto-aggregation ability, swimming and swarming migration diameter, AI-2 activity, extracellular polysaccharide (EPS), and extracellular protein content of V. parahaemolyticus. Fluorescence microscope and scanning electron microscope (SEM) images demonstrated that the Z057-E could efficiently inactivate the living cells, destroy the dense and complete biofilm architectures, and reduce the essential component of the extracellular polymer matrix. Real-time fluorescence quantitative PCR revealed that the Z057-E treatment down-regulated the expression of flagellum synthesis-related genes (flaA, flgM), EPS, and extracellular protein synthesis-related genes (cpsA, cpsQ, cpsR, ompW), QS-related genes (luxS, aphA, opaR), and hemolysin secretion-related genes (toxS, toxR) of V. parahaemolyticus. Thus, our results suggested that L. plantarum Z057 could represent an alternative biocontrol strategy against foodborne pathogens with anti-adhesive, antibiofilm, and antiquorum sensing activities.

Prevalence of and factors associated with unintended pregnancies among sexually active undergraduates in mainland China.

BACKGROUND: Unintended pregnancies (UIP) among unmarried sexually active college students in mainland China have emerged as a major reproductive health issue with detrimental personal and socioeconomic consequences. This cross-sectional study aimed to determine the prevalence and factors associated with UIP among sexually active undergraduates in mainland China. METHODS: Between September 8, 2019 and January 17, 2020, a total of 48,660 participants were recruited across the Chinese mainland to complete the self-administered, structured, online questionnaire. This analysis was restricted to 6347 sexually experienced, never-married 15-26 year old undergraduates. Pearson's Chi square tests and multivariate Logistic regression analyses were performed to identify sociodemographic, familial and individual variables associated with UIP. RESULTS: The overall prevalence of UIP was 17.7%. More specifically, 19.5% of male college students reported they had unintentionally gotten a partner pregnant, while 14.9% of female college students became unintentionally pregnant. Students who experienced UIP were more likely to belong to the older age group (23-26 years), live with only one parent or live without parents at home, report that their family members approve of premarital sex, initiate sexual activity younger than 14 years old and have casual sex partners. Furthermore, females with multiple partners and males who came from low- income households, experienced sexual abuse, perceived difficulties in acquiring condoms and did not know how to use condoms correctly were also at higher risk of experiencing an unintended pregnancy. CONCLUSION: In order to prevent UIP, a comprehensive intervention measure should be taken to target older students and those engaging in risky sexual behaviors, work with young male students to improve condom use skills, improve the availability of free condoms, optimize the involvement of parents and other family members in their children's sex education.

In this study, we aimed to determine the prevalence and factors associated with UIP among sexually active undergraduates in mainland China. Between September 8, 2019 and January 17, 2020, a total of 48,660 participants were recruited from the Chinese mainland to complete the self-administered, structured, online questionnaire. This analysis was restricted to 6347 sexually experienced, never-married 15­26 year old undergraduates. Based on a social-ecological theoretical framework, we ran separate multivariate Logistic regression models for men and women to identify sociodemographic, familial and individual variables associated with UIP. Our findings indicate that the overall prevalence of UIP was 17.7%. More specifically, 19.5% of male college students reported they had unintentionally gotten a partner pregnant, while 14.9% of female college students became unintentionally pregnant. Students who experienced UIP were more likely to belong to the older age group, live with only one parent or live without parents at home, report that their family members approve of premarital sex, initiate sexual activity younger than 14 years old and have casual sex partners. Furthermore, females with multiple partners and males who came from low-income households, experienced sexual abuse, perceived difficulties in acquiring condoms and did not know how to use condoms correctly were also at higher risk of having an unintended pregnancy. In order to prevent UIP, a comprehensive intervention measure should be taken to target older students and those engaging in risky sexual behaviors, work with young male students to improve condom use skills, improve the availability of free condoms, optimize the involvement of parents and other family members in their children's sex education.

Species-Specific Molecular Barriers to SARS-CoV-2 Replication in Bat Cells.

Bats are natural reservoirs of numerous coronaviruses, including the potential ancestor of SARS-CoV-2. Knowledge concerning the interaction between coronaviruses and bat cells is sparse. We investigated the ability of primary cells from Rhinolophus and Myotis species, as well as of established and novel cell lines from Myotis myotis, Eptesicus serotinus, Tadarida brasiliensis, and Nyctalus noctula, to support SARS-CoV-2 replication. None of these cells were permissive to infection, not even the ones expressing detectable levels of angiotensin-converting enzyme 2 (ACE2), which serves as the viral receptor in many mammalian species. The resistance to infection was overcome by expression of human ACE2 (hACE2) in three cell lines, suggesting that the restriction to viral replication was due to a low expression of bat ACE2 (bACE2) or the absence of bACE2 binding in these cells. Infectious virions were produced but not released from hACE2-transduced M. myotis brain cells. E. serotinus brain cells and M. myotis nasal epithelial cells expressing hACE2 efficiently controlled viral replication, which correlated with a potent interferon response. Our data highlight the existence of species-specific and cell-specific molecular barriers to viral replication in bat cells. These novel chiropteran cellular models are valuable tools to investigate the evolutionary relationships between bats and coronaviruses. IMPORTANCE Bats are host ancestors of several viruses that cause serious disease in humans, as illustrated by the ongoing SARS-CoV-2 pandemic. Progress in investigating bat-virus interactions has been hampered by a limited number of available bat cellular models. We have generated primary cells and cell lines from several bat species that are relevant for coronavirus research. The various permissivities of the cells to SARS-CoV-2 infection offered the opportunity to uncover some species-specific molecular restrictions to viral replication. All bat cells exhibited a potent entry-dependent restriction. Once this block was overcome by overexpression of human ACE2, which serves at the viral receptor, two bat cell lines controlled well viral replication, which correlated with the inability of the virus to counteract antiviral responses. Other cells potently inhibited viral release. Our novel bat cellular models contribute to a better understanding of the molecular interplays between bat cells and viruses.

Effect of glucose oxidase treatment on the aroma qualities and release of cooked off-odor components from heat-treated Hami melon juice.

Melon juice produces strong cooked off-odors during heat processing, leading to serious deterioration of aroma quality. In this work, the aroma quality of melon juice, the changes in GOD reaction products, and the interactions of reaction products and cooked off-odor components were analyzed by sensory evaluation, gas chromatography-mass spectrometry/olfactory, ultraperformance liquid chromatography-triple quadrupole mass spectrometry, and isothermal titration calorimetry to study the effect mechanism of glucose oxidase (GOD) on the release of cooked off-odor components from heat-treated melon juice. The results showed that GOD treatment improved the aroma quality mainly by controlling off-odor attributes and maintaining characteristic odor attributes. This was because the reaction products (hydrogen peroxide and gluconic acid) of GOD treatment inhibited the release of cooked off-odor components from heat-treated melon juice through oxidation and hydrophobic effects. Furthermore, these products reduced the loss of characteristic odor compounds by restraining Maillard, degradation, and oxidation reactions during heat processing.

Genome Characterization of Bird-Related Rhabdoviruses Circulating in Africa.

Rhabdoviridae is the most diverse family of the negative, single-stranded RNA viruses, which includes 40 ecologically different genera that infect plants, insects, reptiles, fishes, and mammals, including humans, and birds. To date, only a few bird-related rhabdoviruses among the genera Sunrhavirus, Hapavirus, and Tupavirus have been described and analyzed at the molecular level. In this study, we characterized seven additional and previously unclassified rhabdoviruses, which were isolated from various bird species collected in Africa during the 1960s and 1970s. Based on the analysis of their genome sequences obtained by next generation sequencing, we observed a classical genomic structure, with the presence of the five canonical rhabdovirus genes, i.e., nucleoprotein (N), phosphoprotein (P), matrix protein (M), glycoprotein (G), and polymerase (L). In addition, different additional open reading frames which code putative proteins of unknown function were identified, with the common presence of the C and the SH proteins, within the P gene and between the M and G genes, respectively. Genetic comparisons and phylogenetic analysis demonstrated that these seven bird-related rhabdoviruses could be considered as putative new species within the genus Sunrhavirus, where they clustered into a single group (named Clade III), a companion to two other groups that encompass mainly insect-related viruses. The results of this study shed light on the high diversity of the rhabdoviruses circulating in birds, mainly in Africa. Their close relationship with other insect-related sunrhaviruses raise questions about their potential role and impact as arboviruses that affect bird communities.

Characterization of Novel Rhabdoviruses in Chinese Bats.

Bats, the second largest order of mammals worldwide, harbor specific characteristics such as sustaining flight, a special immune system, unique habits, and ecological niches. In addition, they are the natural reservoirs of a variety of emerging or re-emerging zoonotic pathogens. Rhabdoviridae is one of the most diverse families of RNA viruses, which consists of 20 ecologically diverse genera, infecting plants, mammals, birds, reptiles, and fish. To date, three bat-related genera are described, named Lyssavirus, Vesiculovirus, and Ledantevirus. However, the prevalence and the distribution of these bat-related rhabdoviruses remain largely unknown, especially in China. To fill this gap, we performed a large molecular retrospective study based on the real-time reverse transcription polymerase chain reaction (RT-qPCR) detection of lyssavirus in bat samples (1044 brain and 3532 saliva samples, from 63 different bat species) originating from 21 provinces of China during 2006-2018. None of them were positive for lyssavirus, but six bat brains (0.6%) of Rhinolophus bat species, originating from Hubei and Hainan provinces, were positive for vesiculoviruses or ledanteviruses. Based on complete genomes, these viruses were phylogenetically classified into three putative new species, tentatively named Yinshui bat virus (YSBV), Taiyi bat virus (TYBV), and Qiongzhong bat virus (QZBV). These results indicate the novel rhabdoviruses circulated in different Chinese bat populations.

Production of high sensory quality Shiitake mushroom (Lentinus edodes) by pulsed air-impingement jet drying (AID) technique.

The effect of pulsed air-impingement jet drying (AID) on the sensory qualities of Shiitake mushroom was comprehensively examined compared with hot air drying (HAD) and vacuum freeze-drying (VFD). AID considerably improved the characteristic flavors (onion-like odor and umami) of dried mushrooms by partially inhibiting enzymatic and Maillard reactions. The texture characteristics (rehydration and shrinkage) of AID mushrooms had no significant difference to VFD ones and were better than HAD ones. AID combined the advantages of HAD and VFD technologies and outperformed HAD and VFD in terms of overall quality, though the total content of free amino acids and soluble sugars of AID mushrooms dropped slightly. In summary, AID is a promising drying technology for obtaining high sensory quality Shiitake mushrooms compared to prevailing drying methods.

Isolation and identification of putative precursors of the volatile sulfur compounds and their inhibition methods in heat-sterilized melon juices.

Volatile sulfur compounds, such as dimethyl sulfide, dimethyl disulfide and dimethyl trisulfide, cause the off-flavor in heat-sterilized juices and limit the commercial production of juices. In this study, we investigated the precursors for these volatile sulfur compounds and analyzed the potential inhibition methods. Upon separation of melon juice components using resin column, the dimethyl sulfide precursor was present in the acidic fraction whereas the dimethyl trisulfide precursor was present in neutral and acidic fractions. Exogenous addition experiments indicated S-methyl methionine was the precursor of dimethyl sulfide, and methionine was the precursor of dimethyl disulfide and dimethyl trisulfide. The release of volatile sulfur compounds was reduced by decreasing the pH to 2.0, or by adding epicatechin. We concluded S-methyl methionine and methionine were degraded into volatile sulfur compounds through nucleophilic substitution and Strecker degradation. This study can help establishing protocols for controlling the release of volatile sulfur compounds in heat-sterilized juices.

Bat mammalian orthoreoviruses cause severe pneumonia in mice.

Mammalian orthoreovirus (MRV) infections are ubiquitous in mammals. Increasing evidence suggests that some MRVs can cause severe respiratory disease and encephalitis in humans and other animals. Previously, we isolated six bat MRV strains. However, the pathogenicity of these bat viruses remains unclear. In this study, we investigated the host range and pathogenicity of 3 bat MRV strains (WIV2, 3 and 7) which represent three serotypes. Our results showed that all of them can infect cell lines from different mammalian species and displayed different replication efficiency. The BALB/c mice infected by bat MRVs showed clinical symptoms with systematic infection especially in lung and intestines. Obvious tissue damage were found in all infected lungs. One of the strains, WIV7, showed higher replication efficiency in vitro and vivo and more severe pathogenesis in mice. Our results provide new evidence showing potential pathogenicity of bat MRVs in animals and probable risk in humans.

Revisiting the Classification of Percid Perhabdoviruses Using New Full-Length Genomes.

Perhabdoviruses are a threat to some freshwater fish species raised in aquaculture farms in Europe. Although the genetic diversity of these viruses is suspected to be high, the classification of isolates is still in its infancy, with just one full-length genome available and only partial sequences for a limited number of others. Here, we characterized a series of viruses isolated from percids in France from 1999 to 2009 by sequencing the nucleoprotein (N) gene. Four main clusters were distinguished, all related at varying levels of similarity to one of the two already-recognized species, namely Perch perhabdovirus and Sea trout perhabdovirus. Furthermore, we obtained the complete genome of five isolates, including one belonging to Sea trout rhabdovirus. The analysis of the complete L genes and the concatenated open reading frames confirmed the existence of four main genetic clusters, sharing 69 to 74% similarity. We propose the assignation of all these viral isolates into four species, including two new ones: Perch perhabdovirus 1, Perch perhabdovirus 2, Sea trout perhabdovirus 1 and Sea trout perhabdovirus 2. In addition, we developed new primers to readily amplify specific portions of the N gene of any isolate of each species by conventional PCR. The presence of such genetically diverse viruses in France is likely due to divergent viral populations maintained in the wild and then introduced to experimental facilities or farms, as well as via trade between farms across the European continent. It is now urgent to improve the identification tools for this large group of viruses to prevent their unchecked dissemination.

Characterization of Key Aroma Compounds in Raw and Roasted Peas (Pisum sativum L.) by Application of Instrumental and Sensory Techniques.

Gas chromatography-olfactometry (GC-O) coupled with GC-mass spectrometry (GC-MS) and aroma recombination-omission experiments led to the identification of the key aroma compounds responsible for the different flavors of raw and roasted peas. The results demonstrated that a total of 30 odorants were identified in raw and roasted peas. Nine and twenty compounds were identified as important odorants in raw and roasted peas with odor activity values (OAVs) greater than 1, respectively. Aroma recombination-omission experiments demonstrated that six aroma compounds significantly contributed to the characteristic aroma of peas (p < 0.05). Among these, 3-methylbutanoic acid (OAV = 382) and hexanal (OAV = 280) significantly contributed to the aroma of peas. Fifteen aroma compounds significantly contributed to the characteristic aroma of roasted peas (p < 0.05). Among these, pyrazines and pyranones showed important contribution to the aroma of roasted peas. Roasting increased the variety of key aroma compounds significantly and contributed a nutty flavor to peas. The comprehensive aroma characterization of peas and determination of the effect of roasting on key aroma compound alteration will be helpful for new pea products' flavor quality control.

Co-circulation and characterization of novel African arboviruses (genus Ephemerovirus) in cattle, Mayotte island, Indian Ocean, 2017.

Mayotte is an island located in the Mozambique Channel, between Mozambique and Madagascar, in the South Western Indian Ocean region. A severe syndrome of unknown aetiology has been observed seasonally since 2009 in cattle (locally named "cattle flu"), associated with anorexia, nasal discharge, hyperthermia and lameness. We sampled blood from a panel of those severely affected animals at the onset of disease signs and analysed these samples by next-generation sequencing. We first identified the presence of ephemeral bovine fever viruses (BEFV), an arbovirus belonging to the genus Ephemerovirus within the family Rhabdoviridae, thus representing the first published sequences of BEFV viruses of African origin. In addition, we also discovered and genetically characterized a potential new species within the genus Ephemerovirus, called Mavingoni virus (MVGV) from one diseased animal. Finally, both MVGV and BEFV have been identified in cattle from the same herd, evidencing a co-circulation of different ephemeroviruses on the island. The clinical, epidemiological and virological information strongly suggests that these viruses represent the etiological agents of the observed "cattle flu" within this region. This study highlights the importance of the strengthening and harmonizing arboviral surveillance in Mayotte and its neighbouring areas, including Africa mainland, given the importance of the diffusion of infectious diseases (such as BEFV) mediated by animal and human movements in the South Western Indian Ocean area.

Study of the Inhibitors of Cooked Off-Flavor Components in Heat-Treated XiZhou Melon Juice.

This research applied inhibitors to reduce the content of cooked off-flavor components (dimethyl sulfide, dimethyl disulfide, dimethyl trisulfide, and 3-(methylthio)propanaldehyde) in heat-treated melon juice. The effects of glucose oxidase (GOD) on the formation and release of these four volatile sulfur compounds were also investigated. Results showed that GOD strongly inhibited the formation of the four compounds. In GOD-treated melon juice, S-methylmethionine was strongly protonated and not easily degraded into dimethyl sulfide. Moreover, the release of the dimethyl sulfide that did form was restrained by the hydrophobic interactions of gluconic acid and oxidation by hydrogen peroxide. In addition, gluconic acid (or glucose) and hydrogen peroxide could form a stable complex with methionine in an acidic matrix and thus prevented the methionine from producing 3-(methylthio)propanaldehyde, dimethyl disulfide, and dimethyl trisulfide by the Maillard reaction during heat processing.

Effect of cooking on aroma profiles of Chinese foxtail millet (Setaria italica) and correlation with sensory quality.

The effects of roasting, boiling, and freeze-drying after boiling on volatile aroma compounds in three varieties of Chinese foxtail millet (Setaria italica), namely, Jingu 21, Fenghonggu and Dongfangliang were determined. During boiling significant (p < 0.05) increases in the contents of several unsaturated aldehydes, alcohols, and benzene derivatives were observed, unlike roasting that mainly increased in the contents of pyrazines. Freeze-drying after boiling decreased complexity of flavors, with a reduction in the contents of volatile compounds. Descriptive sensory analysis showed that the maximum intensity of 'popcorn-like' and 'smoky' odors was observed for roasted samples, whereas boiled and pre-boiled-freeze-dried samples were characterized by 'boiled rice' and 'boiled potatoes' odors, respectively. A correlation of odor-active profile data with descriptive sensory analysis clearly established the role of pyrazines such as 2-ethyl-3,5-dimethylpyrazine in contributing to the 'popcorn-like', 'boiled beans', and 'smoky' odors, whereas dienals such as (E,E)-2,4-decadienal were responsible for the 'boiled rice' aroma.

Characterization of Diversity and Probiotic Efficiency of the Autochthonous Lactic Acid Bacteria in the Fermentation of Selected Raw Fruit and Vegetable Juices.

The diversity of indigenous lactic acid bacteria (LAB) in fermented broccoli, cherry, ginger, white radish, and white-fleshed pitaya juices was analyzed using culture-independent and -dependent approaches. The major properties of selected probiotic strains, including dynamic variations in pH, viable cell counts, antibiotic resistance, bacterial adhesion to hydrophobic compounds, and survivability during simulated gastrointestinal transit, were investigated using broccoli as the fermentation substrate. In broccoli and ginger juices, the genus Lactobacillus occupied the dominant position (abundances of 79.0 and 30.3%, respectively); in cherry and radish juices, Weissella occupied the dominant position (abundances of 78.3 and 83.2%, respectively); and in pitaya juice, Streptococcus and Lactococcus occupied the dominant positions (52.2 and 37.0%, respectively). Leuconostoc mesenteroides, Weissella cibaria/soli/confusa, Enterococcus gallinarum/durans/hirae, Pediococcus pentosaceus, Bacillus coagulans, and Lactococcus garvieae/lactis subspecies were identified by partial 16S rRNA gene sequencing. In general, the selected autochthonous LAB isolates displayed no significant differences in comparison with commercial strains with regard to growth rates or acidification in fermented broccoli juice. Among all the isolates, L. mesenteroides B4-25 exhibited the highest antibiotic resistance profile (equal to that of L. plantarum CICC20265), and suitable adhesion properties (adhesion of 13.4 ± 5.2% ∼ 36.4 ± 3.2% and 21.6 ± 1.4% ∼ 69.6 ± 2.3% to ethyl acetate and xylene, respectively). Furthermore, P. pentosaceus Ca-4 and L. mesenteroides B-25 featured the highest survival rates (22.4 ± 2.6 and 21.2 ± 1.4%, respectively), after simulated gastrointestinal transit. These results indicated a high level of diversity among the autochthonous bacterial community in fermented fruit and vegetable juices, and demonstrated the potential of these candidate probiotics for applications in fermentation.