Mechanisms underlying the formation of main volatile odor sulfur compounds in foods during thermal processing.

Volatile sulfur compounds (VSCs) significantly influence food flavor and garner considerable attention in flavor research due to their low sensory thresholds, diverse odor attributes, and high reactivity. Extensive research studies have explored VSC formation through thermal processes such as the Maillard reaction, thermal pyrolysis, oxidation, and enzymatic reactions. However, understanding of the specific reaction mechanisms and processes remains limited. This is due to the dispersed nature of existing studies, the undefined intermediates involved, and the complexity of the matrices and processing conditions. Given these limitations, the authors have shifted their focus from foods to sulfides. The structure, source, and chemical characteristics of common precursors (sulfur-containing amino acids and derivatives, thiamine, thioglucoside, and lentinic acid) and their corresponding reactive intermediates (hydrogen sulfide, thiol, alkyl sulfide, alkyl sulfenic acid, and thial) are provided, and the degradation mechanisms, reaction rules, and matrix conditions are summarized based on their chemical characteristics. Additionally, the VSC formation processes in several typical foods during processing are elucidated, adhering to these identified rules. This article provides a comprehensive overview of VSCs, from precursors and intermediates to end products, and is crucial for understanding the mechanisms behind VSC formation and managing the flavor qualities of processed foods.

Application of legumes in plant-based milk alternatives: a review of limitations and solutions.

In recent years, a global shift has been observed toward reducing the consumption of animal-derived foods in favor of healthier and more sustainable dietary choices. This has led to a steady growth in the market for plant-based milk alternatives (PBMAs). Projections suggest that this market will reach a value of USD 69.8 billion by 2030. Legumes, being traditional and nutritious ingredients for PMBAs, are rich in proteins, dietary fibers, and other nutrients, with potential health benefits such as anticancer and cardiovascular disease prevention. In this review, the application of 12 legumes in plant-based milk alternatives was thoroughly discussed for the first time. However, compared to milk, processing of legume-based beverages can lead to deficiencies such as nutritional imbalance, off-flavor, and emulsion stratification. Considering the potential and challenges associated with legume-based beverages, this review aims to provide a scientific comparison between legume-based beverages and cow's milk in terms of nutritional quality, organoleptic attributes and stability, and to summarize ways to improve the deficiencies of legume-based beverages in terms of raw materials and processing method improvements. In conclusion, the legume-based beverage industry will be better enhanced and developed by improving the issues.

Quantification- and structural-taste intensity of umami peptides from Agrocybe aegerita through quantitative structure-activity relationship.

Agrocybe aegerita, one of the edible mushroom varieties, is popular among consumers for its umami taste. Umami peptides, including EV, EG, EY, ENG, ECG, DEL, DDL, PEG, PEEL, DGPL, and EDCS are the main umami compounds in A. aegerita. In this study, when the concentration of these 11 umami peptides was 5 mg/mL, the corresponding relative umami intensity (measured by MSG concentration) ranged from 4.457 to 5.240 mg/mL, with DDL being the highest. All umami peptides exhibited better umami taste under neutral and weakly acidic conditions (pH 6-7). EY and ENG, with a higher umami intensity at 70 °C, were more suitable for a wide application in thermally processed foods. Additionally, the relationship between the structure and strength of umami peptides was explored using a three-dimensional quantitative structure-activity relationship model with an R2 of 0.987. Overall, umami peptides in A. aegerita possess strong potential for application in food processing.

Investigation of umami peptides and taste mechanisms in Agrocybe aegerita: based on sensory evaluation and molecular docking techniques.

In the present study, sensory orientation and instrumental analysis were employed to separate, purify, and identify umami peptides in Agrocybe aegerita hydrolysate. Using UPLC-ESI-Q-TOF MS, 11 potential umami peptides (EY, EG, EV, ENG, PEG, DEL, ECG, DDL, PEEL, EDCS and DGPL) were identified from the screened fractions. Moreover, sensory evaluation and E-tongue results showed that the identified umami peptides had umami attributes, within an umami threshold range of 0.0625-0.25 mg mL-1. In addition, DDL and DEL exhibited the highest umami flavor intensity. Molecular docking analysis further showed that 4 umami peptides (namely, EY, EG, ECG, and DGPL) entered the T1R1 cavity of the umami receptor. Additionally, 4 umami peptides (namely, EV, ENG, DEL, and EDCS) could be embedded in the binding pocket of the T1R3 cavity. Furthermore, 3 umami peptides (PEG, DDL, and PEEL) strongly interacted with T1R1/T1R3. Thus, the findings collectively indicated that the predominant interacting forces between umami peptide and umami receptor are hydrogen bonding and hydrophobic interactions. Finally, it was shown that the primary binding sites of T1R1 were residues Ser109, Gln52 and Ser148, while the primary binding sites of T1R3 were residues Ser172, Arg277 and Ala170. The study identified the umami peptides in A. aegerita for the first time, which provided more information for the umami research of A. aegerita and provided the theoretical basis for the further development and utilization of A. aegerita.

A dysprosium(III)-based triple helical-like complex as a turn-on/off fluorescence sensor for Al(III) and 4,5-dimethyl-2-nitroaniline.

A novel triple helical-like complex [Dy2K2L3(NO3)2]·3DMF (1) based on a designed Schiff base N'1,N'3-bis((E)-3-ethoxy-2-hydroxybenzylidene)-malonohydrazide (H4L) was synthesized with good chemical and thermal stabilities. Single-crystal X-ray structural analysis showed that 1 presents a tetranuclear triple helical-like structure via the coordination mode of Dy : K : L with 2 : 2 : 3 stoichiometry. Fluorescence measurements showed that 1@EtOH has excellent fluorescence turn-on/off response ability for aluminium ions and 4,5-dimethyl-2-nitroaniline (DMNA) with outstanding selectivity, sensitivity, and anti-interference ability. The calculated limit of detection (LOD) values for 1@EtOH to Al3+ and DMNA were found to be 0.53 and 3.33 µM, respectively. Density functional theory (DFT) calculation showed that the fluorescence response mechanism can be explained by the photoinduced electron transfer (PET) mechanism; meanwhile, the inner filter effect (IFE) of DMNA can also affect the emission of 1@EtOH.

Characterization of odor profiles of pea milk varieties and identification of key odor-active compounds by molecular sensory science approaches using soybean milk as a reference.

This study investigated the odor profiles of four pea milk varieties based on sensory evaluation, electronic nose (E-nose), and gas chromatography-mass spectrometry (GC-MS) with soybean milk as a reference. Compared to soybean milk, pea milk exhibited lower intensity of beany, oil-oxidation, and mushroom flavors as well as higher intensity of grassy/green and earthy flavors. ZW.6 pea milk was selected for further identification of key odor-active compounds using molecular sensory science approaches. Using headspace solid phase microextraction (HS-SPME), solvent-assisted flavor evaporation (SAFE), and dynamic headspace sampling (DHS) combined with comprehensive gas chromatography-olfactometry-mass spectrometry (GC × GC-O-MS), 102 odor-active compounds were detected in ZW.6 pea milk. Among these, 19 compounds exhibiting high flavor dilution (FD) factors were accurately quantitated. Ten key odor-active compounds were ultimately identified through aroma recombination and omission experiment. Aldehydes and alcohols significantly contribute to the odor profile of pea milk.

Within-Family Associations Between Parental Psychological Control and Externalizing Problems Among Chinese Children: Links to Between-Family Mindful Parenting.

Previous longitudinal studies have documented bidirectional associations between parental psychological control and children's externalizing problems over months or years. However, most studies have only examined these associations at the between-family level, and there is a lack of intensive longitudinal data (ILD) on psychological control and children's externalizing problems. Thus, this daily diary study examined the bidirectional associations between parental psychological control and externalizing problems among Chinese children. Further, we explored whether between-family mindful parenting linked to the mean levels and daily fluctuations of parental psychological control and children's externalizing problems. The sample included 71 parents of children between 7 to 13 years old (50.7% male; Mage = 9.92, SD = 1.46). Our findings indicate that at the within-family level, higher parental psychological control than usual predicted increases in externalizing problems among children reported by parents the next day, but not vice versa. Furthermore, between-family mindful parenting was negatively associated with the mean levels of psychological control and children's externalizing problems, as well as with fewer fluctuations of parental psychological control. This study contributes to the understanding of the within-family associations between parental psychological control and children's externalizing problems on a daily basis. Finally, we discuss implications for prevention and intervention programs targeting negative parenting and child externalizing problems.

Alteration of volatile profiles in heat-sterilized cloudy muskmelon juice as affected by pectin fractions.

BACKGROUND: Flavor is considered as a key quality attribute of fruit juice affecting consumer acceptance. During processing, the flavor loss of cloudy juice always occurs due to the variations of juice cloud particles. Pectin, a major component of cloud particles, plays an important role in cloud stability. In this work, we focused on the effects of variation of three pectin fractions caused by gentle centrifugation and clarification on the physicochemical properties, volatile content and sensory profile of heat-sterilized muskmelon cloudy juice. RESULTS: Centrifugation treatment reduced the total soluble solids and viscosity of cloudy juice and increased cloud stability. With centrifugation increased, the contents of most monosaccharides in the three pectin fractions were reduced. Most aroma-active aldehydes and alcohols, such as (2E,6Z)-nonadienal, 1-octen-3-ol and (E)-non-2-enal, after gentle centrifugation and clarification, were maintained, but most esters were decreased. The volatile compositions were highly related to the three pectin fractions. The addition of chelator-soluble pectin and sodium carbonate-soluble pectin could decrease the formation of dimethyl trisulfide and dimethyl disulfide in clarified juice, thereby improving the sensory profile. CONCLUSION: The results suggested that endogenous chelator-soluble pectin and sodium carbonate-soluble pectin can be used in heat-sterilized fruit juice to improve flavor quality, with an emphasis on a significant reduction in volatile sulfur compounds. © 2023 Society of Chemical Industry.

Marine-Derived Fungi as a Valuable Resource for Amylases Activity Screening.

Marine microbial enzymes including amylases are important in different industrial production due to their properties and applications. This study was focused on the screening of marine-derived fungi for amylase activities. First, we isolated a number of fungi from the sediments of the South China Sea. By the method of dish screening (in vitro), we subsequently obtained a series of amylase-producing fungal strains. The cell-lysate activities of amylases produced by marine fungi toward starch hydrolysis were achieved with the dinitrosalyicylic acid (DNS) method. In addition, the effect of pH and temperature on amylase activities, including thermal and pH stability were discussed. Results showed that out of the 57 isolates with amylase-producing activities, fungi Aspergillus flavus 9261 was found to produce amylase with the best activity of 10.7482 U/mg (wet mycelia). The amylase of Aspergillus flavus 9261 exhibited remarkable thermostability and pH stability with no activity loss after incubation at 50 °C and pH 5.0 for 1 h, respectively. The results provide advances in discovering enzymes from marine-derived fungi and their biotechnology relevance.

Factors affecting aroma compounds in orange juice and their sensory perception: A review.

Orange juice is the most widely consumed fruit juice globally because of its pleasant aromas and high nutritional value. Aromas, contributed by free and bound aroma compounds, are an important attribute and determine the quality of orange juice and consumer choices. Aldehydes, alcohols, esters, and terpenoids have been shown to play important roles in the aroma quality of orange juice. Many factors affect the aroma compounds in orange juice, such as genetic makeup, maturity, processing, matrix compounds, packaging, and storage. This paper reviews identified aroma compounds in free and bound form, the biosynthetic pathways of aroma-active compounds, and factors affecting aroma from a molecular perspective. This review also outlines the effect of variations in aroma on the sensory profile of orange juice and discusses the sensory perception pathways in human systems. Sensory perception of aromas is affected by aroma variations but also converges with taste perception. This review could provide critical information for further research on the aromas of orange juice and their manipulation during the development of products.

Chemoreceptors from the commensal gut Roseburia rectibacter bind to mucin and trigger chemotaxis.

Chemotaxis is crucial for bacterial adherence and colonization of the host gastrointestinal tract. Previous studies have demonstrated that chemotaxis affects the virulence of causative pathogens and the infection in the host. However, the chemotactic abilities of non-pathogenic and commensal gut bacteria have rarely been explored. We observed that Roseburia rectibacter NSJ-69 exhibited flagella-dependent motility and chemotaxis to a variety of molecules, including mucin and propionate. A genome-wide analysis revealed that NSJ-69 has 28 putative chemoreceptors, 15 of which have periplasmic ligand-binding domains (LBDs). These LBD-coding genes were chemically synthesized and expressed heterologously in Escherichia coli. Intensive screening of ligands revealed four chemoreceptors bound to mucin and two bound to propionate. When expressed in Comamonas testosteroni or E. coli, these chemoreceptors elicited chemotaxis toward mucin and propionate. Hybrid chemoreceptors were constructed, and results showed that the chemotactic responses to mucin and propionate were dependent on the LBDs of R. rectibacter chemoreceptors. Our study identified and characterized R. rectibacter chemoreceptors. These results will facilitate further investigations on the involvement of microbial chemotaxis in host colonization.

Salivary Markers of Stress in Grandparents Rearing Grandchildren in Rural Appalachia: The Role of Mental Health, Religiosity, and Social Support.

This study examines changes in salivary cortisol and alpha-amylase among grandparents rearing grandchildren in rural Appalachia. Grandparent-caregivers experience greater stress than non-grandparent-caregivers. Participants included 20 grandparent-caregivers and a child for which they cared, who completed questionnaires assessing family functioning and mental health via interview. Grandparent-caregivers provided morning saliva samples once a year for two years. For grandparent-caregivers low in social support and religiosity, grandparent-caregiver depressive symptoms, child depressive symptoms, and child stress were associated with increased grandparent-caregiver salivary alpha-amylase. For grandparent-caregivers high in social support and religiosity, child depressive symptoms, child stress, and child aggression were associated with increased grandparent-caregiver cortisol.

Formation mechanism and functional properties of walnut protein isolate and soy protein isolate nanoparticles using the pH-cycle technology.

Walnut protein isolate (WPI) is a nutritious protein with poor solubility, which severely limits its application. In this study, composite nanoparticles were prepared from WPI and soy protein isolate (SPI) using the pH-cycle technology. The WPI solubility increased from 12.64 to 88.53% with a WPI: SPI ratio increased from 1: 0.01 to 1: 1. Morphological and structural analyses illustrated that interaction forces with hydrogen bonding as the main effect jointly drive the binding of WPI to SPI and that protein co-folding occurs during the neutralization process, resulting in a hydrophilic rigid structure. In addition, the interfacial characterization showed that the composite nanoparticle with a large surface charge enhanced the affinity with water molecules, prevented protein aggregation, and protected the new hydrophilic structure from damage. All these parameters helped to maintain the stability of the composite nanoparticles in a neutral environment. Amino acid analysis, emulsification capacity, foaming, and stability analysis showed that the prepared WPI-based nanoparticles exhibited good nutritional and functional properties. Overall, this study could provide a technical reference for the value-added use of WPI and an alternative strategy for delivering natural food ingredients.

Identification and validation of core microbes associated with key aroma formation in fermented pepper paste (Capsicum annuumL.).

Fermented peppers are usually obtained by the spontaneous fermentation of microorganisms attached to fresh peppers, and the variable microbial composition would lead to inconsistencies in flavor between batches. To demonstrate the roles of microorganisms in flavor formation, the core microbes closely associated with the key aroma compounds of fermented pepper paste were screened and validated in this study. Lactobacillus was the dominant bacterial genus in fermented pepper paste, whereas the main fungal genera were Alternaria and Kazachstania. Nine strains of the genera Lactobacillus, Weissella, Bacillus, Zygosaccharomyces, Kazachstania, Debaryomyces, and Pichia were isolated from fermented pepper paste. Eleven key aroma compounds were identified using gas chromatography combined with olfactometry and relative odor activity values. Correlation analysis showed that Zygosaccharomyces and Kazachstania were positively correlated with the majority of the key aroma compounds, whereas Lactobacillus was negatively correlated with them. Thus, Zygosaccharomyces and Kazachstania were identified as core genera associated with the key odorants. Finally, Zygosaccharomyces bisporus, Kazachstania humilis, and Lactiplantibacillus plantarum were used as starter cultures for fermented peppers, confirming that Z. bisporus and K. humilis were more beneficial for the key aroma compounds (e.g., acetate, linalool, and phenyl ethanol) rather than L. plantarum. This study contributed to understanding the flavor formation mechanism and provided references for the quality control of food fermentation.

Comparison of aroma active compounds in cold- and hot-pressed walnut oil by comprehensive two-dimensional gas chromatography-olfactory-mass spectrometry and headspace-gas chromatography-ion mobility spectrometry.

Aroma composition of cold-pressed walnut oil (CWO) and hot-pressed walnut oil (HWO) was analyzed by comprehensive two-dimensional gas chromatography-olfactory-mass spectrometry (GC × GC-O-MS) and headspace-gas chromatography-ion mobility spectrometry (HS-GC-IMS). A total of 83 and 197 compounds were identified in the CWO and HWO, respectively; among these, 76 and 123 compounds were sniffed exclusively by GC × GC-O-MS, respectively. A total of 36 volatile compounds were detected by HS-GC-IMS, of which 10 in CWO and 32 in HWO. Based on of flavor dilution (FD) factors, odor-activity values (OAVs), and recombination and omission experiments, 1-octen-3-ol, cyclohexanol, and benzaldehyde were found to be the key aroma-active compounds in CWO, while 3-methylbutanal, (E,E)-2,4-nonadienal, nonanal, 1-octen-3-ol, 3-pentanol, 1-octanol, and furfural were the key aroma-active compounds in HWO. Moreover, Maillard reaction and lipid oxidation were found to play an important role in flavor formation in HWO. This study provides a guide to improve the quality of walnut oil based on aroma characteristics.

Mothers' emotional expressivity in urban and rural societies: Salience and links with young adolescents' emotional wellbeing and expressivity.

This research aims to investigate the salience of mothers' emotional expressivity and its links with adolescents' emotional wellbeing and expressivity in an urban society endorsing more individualism and a rural society ascribing to more collectivism. By comparing Chinese urban (N = 283, M age = 14.13) and rural (N = 247, M age = 14.09) adolescents, this research found that urban mothers' expression of positive-dominant and positive-submissive emotions (PD and PS) were more common while expression of negative-dominant (ND) emotions was less common than rural mothers'. PD and PS had significant links with urban and rural adolescents' increased emotional expressivity and self-esteem, however, only significantly related to urban adolescents' decreased depression but not with rural adolescents'. ND had significant links with both urban and rural adolescents' expression of negative emotions, however, only significantly correlated with urban adolescents' less level of self-esteem and rural adolescents' more expression of positive emotions. No significant difference was found in the salience of urban and rural mothers' expression of negative-submissive (NS) emotions, which positively related to both urban and rural adolescents' depression and emotional expressivity. Moreover, we found that adolescents' emotional wellbeing (i.e., self-esteem and depression) mediated the relationship between mothers' emotional expressivity and adolescents' expressivity in both societies. Overall, the study findings document that the salience of mothers' emotional expressivity and its relations with adolescents' emotional adjustment differ between urban and rural societies.

Identification of aroma active compounds in walnut oil by monolithic material adsorption extraction of RSC18 combined with gas chromatography-olfactory-mass spectrometry.

A novel extraction method of volatile aroma compounds (VACs) from walnut oil (WO) using monolithic material adsorption extraction (MMSE) was developed herein, and its efficiency was compared with the conventional extraction method based on solid-phase microextraction (SPME) combined with gas chromatography-olfactory-mass spectrometry (GC-O-MS). After protocol optimization of MMSE-RSC18, 77 volatile compounds (38 ones can be sniffed) were extracted from WO, thus having a better performance compared to SPME (56 volatile compounds, 35 ones can be sniffed). Subsequently, based on flavor dilution factors (FDs), odor activity values (OAVs), and recombination and omission experiments, key aroma-active compounds in WO were 1-octen-3-ol (OAV = 82.58), (E)-2-decenal (OAV = 4.10), linalool (OAV = 2.37), γ-dodecalactone (OAV = 2.30), 2-pentylfuran (OAV = 1.62), (E)-2-nonenal (OAV = 1.14) and pentanal (OAV = 1.04). Collectively, compared to HS-SPME, MMSE-RSC18 provided higher capture efficiency of VACs, enabling efficient extraction and analysis of sample aromas.

Low-frequency ultrasonic treatment: A potential strategy to improve the flavor of fresh watermelon juice.

A molecular sensory science approach was used to explore the effects of ultrasonic treatment on aroma compounds of watermelon juice. Watermelon juice was submitted to ultrasonic power at 325 W for 20 min. Ultrasonic treatment reduced odor related to cucumber and green descriptors, whilst significantly improved odors related to sweet, floral, and fruity descriptors, thus contributing to the overall flavor of watermelon juice. Compared with untreated watermelon juice, the amount and concentration of volatile compounds in ultrasonicated watermelon juice increased by 82.50% and 111.84%, respectively. Notably, 22 alkene compounds were newly formed in ultrasonicated watermelon juice, which contributed to sweet and fruity aroma of watermelon juice. The findings of the present study suggest that ultrasonic treatment may be a potential method to improve the overall flavor of watermelon juice.

Roasting pretreatment of walnut (Juglans regia L.) kernels: improvement of the oil flavor profile and correlation with the chemical composition.

The present study focused on the role of roasting pretreatment in improving the flavor of WOs. In total, 71 volatile compounds were detected, 35 odorants were perceived, and 17 aroma-active compounds were identified in WOs by using headspace-solid phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS) and aroma extract dilution analysis of gas chromatography-olfactometry (AEDA/GC-O). The results indicate that extended roasting pretreatment is effective in generating aldehydes and pyrazine aroma-active compounds in WOs. The correlation between the aroma-active compounds and chemical composition was identified by Pearson correlation analysis. The branched-chain aldehyde, 3-methylbutanal, is a Maillard reaction product with ribose as a precursor. Pyrazine aroma-active compounds were also related to ribose, with absolute correlation coefficients of 0.85 to 0.96; among pyrazine compounds, 2-ethyl-5-methylpyrazine showed strong correlation with isoleucine and arginine, while 2-methylpyrazine and 2,3,5-trimethylpyrazine showed strong correlation with glycine, lysine, and histidine. The determination of the effect of roasting on aroma-active compound alteration and the study of aroma precursors will be helpful for walnut oils' flavor quality control, which directly enable their industrial application.