Volatile Profile Research Articles

Leaf Size Determines Damage‐ and Herbivore‐Induced Volatile Emissions in Maize

ABSTRACTStress‐induced plant volatiles play an important role in mediating ecological interactions between plants and their environment. The timing and location of the inflicted damage is known to influence the quality and quantity of induced volatile emissions. However, how leaf characteristics and herbivore feeding behaviour interact to shape volatile emissions is not well understood. Using a high‐throughput volatile profiling system with high temporal resolution, we examined how mechanical damage and herbivore feeding on different leaves shape plant‐level volatile emission patterns in maize. We then tested feeding patterns and resulting consequences on volatile emissions with two generalist herbivores (Spodoptera exigua and Spodoptera littoralis), and assessed whether feeding preferences are associated with enhanced herbivore performance. We found maize seedlings emit more volatiles when larger leaves are damaged. Larger leaves emitted more volatiles locally, which was the determining factor for higher plant‐level emissions. Surprisingly, both S. exigua and S. littoralis preferentially consumed larger leaves, and thus maximize plant volatile emission without apparent growth benefits. Together, these findings provide an ecophysiological and behavioural mechanism for plant volatile emission patterns, with potentially important implications for volatile‐mediated plant‐environment interactions.

Exploring structure, volatile profile, physicochemical and functional properties of raw and extruded- cooked lentil flours for their use in bakery products

Exploring structure, volatile profile, physicochemical and functional properties of raw and extruded- cooked lentil flours for their use in bakery products

Comparison of the effects of two soy waste-based culture media on the technological properties of Lacticaseibacillus paracasei 90 as adjunct culture in miniature Cremoso cheese.

We compared the effects of two waste-based culture media (M1 and M2) on the technological properties of Lacticaseibacillus paracasei 90 (L90) for its application as a secondary culture in Cremoso cheese. The following parameters were studied at different ripening times: pH (7, 20, and 40 d), microbiological counts, carbohydrates and organic acids (7 and 40 d), moisture, fat, protein and volatile compounds (40 d). The viability and the metabolic performance of the strain in cheeses were also verified along ripening. Lactobacilli counts in experimental cheeses manufactured with L90 were ~8 log CFU/g at 40 d, meanwhile adventitious lactobacilli reached ~4 log CFU/g in the control cheese (made without L90). The levels of lactic acid, citric acid and pyruvic acid were similar among cheeses at 40 d, reaching levels of ~1433 mg/100 g, ~172 mg/100 g, and 7 mg/100 g, respectively. However, the concentration of lactic acid showed numerical differences between experimental and control cheeses. The cheeses made with the adjunct culture showed lower residual galactose (< 588 mg/100 g) in comparison with the control cheese (836 mg/100 g), highlighting the potential of L90 to play a bioprotective role. In the same vein, orotic and hippuric acids were metabolized at different degrees in cheeses made with L90, reaching levels of < 3.7 mg/100 g and < detection limit, respectively, at 40 d. In general, volatile compounds profiles were not negatively affected by the culture media used. On the contrary, the production of key aroma compounds (diacetyl and acetoin) was positively affected by the growth of L90 in these alternative media. The results demonstrated that the L90 strain could be used as an adjunct culture in Cremoso cheese, regardless of the culture media employed for its growth.

Chrysanthemum morifolium Ramat. as a traditional tea material: Unraveling the influence of kill-green process on drying characteristics, phytochemical compounds, and volatile profile

The dried capitulum of chrysanthemums is a traditional material in scented tea, and the kill-green process is a critical step in determining their quality. However, the changes in the physicochemical properties during kill-green and the mechanisms by which these changes affect drying characteristics, metabolic components, and aroma profiles remain unclear. Therefore, this study investigated the changes in water status, polyphenol oxidase and peroxidase activities, and microstructure during high-humidity air impingement kill-green (HHAIK) and steam kill-green (SK), and their effects on drying behavior, color, phytochemicals, and volatile profile of dried chrysanthemums. Results showed that the kill-green process increased the freedom degree of immobile water, reduced the relative content of free water, and induced microstructure alterations, thus enhancing the water diffusion and shortening the subsequent drying time by up to 46.15 %. Compared to SK, HHAIK more rapidly inactivated PPO and POD, causing an improved color profile of dried samples. Dried samples treated with HHAIK for 60 s exhibited higher retention of 9 individual phenolics, total sugar, amino acids, and volatile compounds, thus resulting in higher sensorial acceptance than those treated with SK for 60 s. This study offers theoretical insights and technical support for the future development of high-quality chrysanthemum products.

Volatile organic compounds profile of sebum from patients with Parkinson’s disease by gas chromatography-ion mobility spectrometry

Volatile organic compounds profile of sebum from patients with Parkinson’s disease by gas chromatography-ion mobility spectrometry

Volatile and Non-Volatile Compounds Profiling of Brazilian Pitanga (Eugenia uniflora L.) Varieties During Ripening using Gas Chromatography-Mass Spectrometry Approach

Brazil is home to a rich biodiversity of native edible fruits renowned for their health-promoting compounds and flavors. Among these, Eugenia uniflora L. (Brazilian pitanga) is particularly notable. The fruit varies in color from yellow to purple and is prized for its intense aroma and versatile taste profile. However, information about the compounds responsible for their nutritional and sensory potential is still limited. This study analyzed volatile compounds and metabolites in yellow, red and purple pitanga fruits (Eugenia uniflora) at various ripening stages, exploiting a metabolomics approach. Yellow pitanga had 30 volatile compounds, with esters (40%), terpenes (26.67%) and aldehydes (16.67%) constituting 83.34% of identified volatile compounds. Red pitanga featured 26 volatile compounds, primarily terpenes and esters (each 30.77%) and aldehydes (15.38%), making up 76.92%. Purple pitanga contained 39 volatile compounds, with terpenes and esters (each 35.90%) and aldehydes (17.95%), totaling 89.75% of identified volatile compounds. Across all pitanga types, 124 metabolites were identified, including saturated fatty acids (17.74%), terpenes (17.74%) and sugars (16.93%), constituting 52.41% of identified metabolites. Future studies should provide nutritional information, consumption methods and industrial applications for pitanga fruits, focusing on sensory analysis, health benefits, preservation and breeding to enhance bioactive compounds and flavor.

Drying Methods of Duck Blood: Changes in Volatile Components and Physicochemical Properties

This study investigated the physicochemical properties and volatile components of duck blood powder to determine its quality characteristics based on drying methods. The drying methods of duck blood samples used were freeze drying (FD), hot air drying (HD), spray drying (SD), and vacuum drying (VD). Duck blood powder treated with HD presented the lowest lightness and the highest carbonyl content. The VD-treated powder exhibited the highest water activity and redness. The composition of volatile compounds in duck blood varied based on the drying method, with VD presenting the highest total relative concentration but the least number of identified compounds. The most abundant compound was d-limonene, which was found in all the samples, followed by hexanal in VD and SD, p-xylene in FD, and trimethylamine in HD. Principal component analysis and heatmap analysis demonstrated that duck blood samples processed using different drying methods exhibited distinct volatile compound profiles, with HD, FD, SD, and VD samples associated with specific chemical groups. Multiple factor analysis revealed distinct correlations between drying methods and the physicochemical properties of duck blood, with VD samples showing higher water activity, aldehydes, and ketones, whereas HD samples exhibited increased carbonyl content and acids, highlighting the influence of heat on protein oxidation. VD method, therefore, presents excellent characteristics in terms of time and quality during the powdering process to increase the industrial utilization of duck blood. These findings provide valuable insights for the food industry, enabling the selection of appropriate drying methods that preserve the desired qualities of duck blood, thereby enhancing its commercial viability and potential application in a variety of food products.

Characterization of volatile compounds profiles and identification of key volatile and odor-active compounds in 40 sweetpotato (Ipomoea Batatas L.) varieties

Sweetpotato with different flesh colors exhibits significant differences in flavor. Nevertheless, research on the identification of the key aromatic compounds in sweetpotato is scarce. Therefore, 40 primary sweetpotato varieties with different flesh colors were analyzed by HS-SPME/GC–MS to characterize the volatile compounds. A total of 121 volatile compounds were detected, with aldehydes, furans and terpenes being the most abundant components. Additionally, 35 compounds were identified as the key aromatic compounds by OAV > 1, of which 17 were found in all varieties and hence considered as the major components of sweetpotato aroma. Further analysis demonstrated that the yellow-fleshed sweetpotato had the strongest aroma, which was presumed due to the aldehydes like (E,E)-2,4-heptadienal, nonanal, (E,E)-2,4-decadienal,etc. that were produced during the degradation of unsaturated fatty acids. The unique sweety and floral aroma of orange-fleshed sweetpotato might be attributed to apocarotenoid volatiles (trans-beta-ionone, β-ionone, geranylacetone, etc.), the derivates of carotenoids. The purple-fleshed sweetpotato exhibited weak aroma with a significantly high terpenoids concentration. Overall, these findings may be the main reason for the different aromas of different colored sweetpotatoes and provides insights into sweetpotato aroma and a theoretical basis for improving sweetpotato aroma.

Vacuum-Assisted Headspace Solid Phase Microextraction for Monitoring Ripening-Induced Changes in Tomato Volatile Profile

This work proposes, for the first time, the use of vacuum-assisted headspace solid phase microextraction (Vac-HS-SPME) for studying the free volatiles in tomato fruits. Initially, a comparative optimization between Vac-HS-SPME and regular HS-SPME was conducted, examining the effects of sampling time (15-60 min) and temperature (40 and 60°C) on the extraction of 29 target compounds from tomato puree samples. Compared to regular HS-SPME, sampling under vacuum resulted in the detection of nine additional analytes at 40°C, and an extra three at 60°C. The optimized methods (45 minutes sampling with Vac-HS-SPME at 40°C and regular HS-SPME at 60°C) were then successfully applied for the semi-quantitative comparison of free volatiles during on-plant ripening. These studies revealed an increase in volatiles across the six ripening stages considered (mature green, breaker, turning, pink, light red and red ripe) that was dominated by aldehydes. Compared to HS-SPME, the optimized Vac-HS-SPME showed substantial improvement in extraction efficiencies, and enabled the detection of key volatiles at earlier ripening stages, such as the breaker and turning stages. Overall, compared to the regular method, this study demonstrated that Vac-HS-SPME is a powerful approach that provides additional insights on free volatiles in fruits, even when sampling at lower temperatures.

Alpine pasture plant species affect in vitro rumen methane production and kinetics

This study aimed to evaluate the influence of different plant species widespread in alpine pastures on in vitro rumen fermentation parameters and methane kinetic production. A total of 11 plant species were sampled at the beginning of the grazing season and used as substrates in an in vitro batch fermentation system. After 24h of fermentation, plants affected volatile fatty acids profiles, ammonia yield, and dry matter (DM) digestibilities. Carum carvi, Ranunculus. acris and Festuca rubra showed the highest total production of methane per unit of digested DM while Potentilla erecta was the species that produced less methane. In terms of methane as a percentage of the total gas, F. rubra had the highest value (28.9%) while R. acris had the lowest (24.2%). Total gas and methane production were monitored continuously and the percentage of methane in total gas was fitted with the Gompertz model. Plants differed significantly (p < .01) in methane production kinetics, including production rate decline (A), asymptotic methane concentration (B), time to maximum fermentation rate (TMFR), and maximum fermentation rate (MFR). C. carvi, Prunella grandiflora, and R. acris showed high values of MFR and the top values in the production rate decline (A > 0.9). The two grasses (F. rubra and Poa alpina) together with Hypericum maculatum showed an opposite behaviour with low values in MFR, A and a longer TMFR. The results of the methane production kinetics allow for an in-depth evaluation of plant species, adding further information to those registered at the end of fermentation.

Chemical profiling and clustering of Piperaceae revealed by volatilomics analysis

The Piperaceae family is one of the aromatic plants that have a distinctive odor and is known to have tremendous benefits in human life. Piperaceae is used as raw material for medicines, spices, antibacterial, antiviral, and insecticides. Research on the composition of volatile chemical compounds in Piperaceae members is still limited. This study aims to extract volatile chemical compounds in the Piperaceae family and classify Piperaceae members based on their volatile compounds. The type of research is laboratory research. The research samples were leaves of ten species of Piperaceae members, namely Piper cubeba, P. nigrum, P. betle, P. ornatum, P. retrofractum, P. sarmentosum, Peperomia pellucida, Peperomia scandens, Peperomia caperata, and Peperomia maculosa. The research instrument was an observation sheet of SPME-GCMS analysis results. Data in the form of metabo-analysis was obtained from laboratory analysis using SPME-GCMS by producing a comprehensive volatile compound profile of the Piperaceae family and revealing differences between species. The results of SPME-GCMS analysis on the Piperaceae family obtained 197 identified volatile chemical compounds. The largest group of chemical compounds in 10 species of the family consists of sesquiterpene (16.2%), monoterpene (11.7%), sesquiterpenoid (7.1%), alcohol (6.1%), aldehyde (4.6%), terpene (4.1%), terpenoid (4.1%), alkene (3%), fatty acid (2.5%), ketone (2.5%), phenol (2.5%), alkane (2%) and other groups less than 2%. Characteristics of typical compounds in the genus Peperomia amounted to 10, namely Alpha-pinene, (-)-; Camphene; 2-beta-pinene; l-Limonene; Nonanal; (-)-.beta.-Elemene; alpha.-Copaene; Germacrene D; cis-caryophyllene; Bicycloelemene. In the genus Piper, the variation in the character of volatile chemical compounds is very large, typical characteristics possessed by 6 Piper species are alpha-pinene, (-)-; alpha.-Copaene; alpha.-Humulene; (-)-beta.-Elemene; and trans-Caryophyllene. The study concluded that 197 volatile compounds from 10 Piperaceae species had been identified. The results of this study can be recommended that the Piperaceae family can be optimized for public health.

Monitoring of the Dry-Curing Process in Iberian Ham Through the Evaluation of Fat Volatile Organic Compounds by Gas Chromatography-Ion Mobility Spectrometry and Non-Destructive Sampling.

The current quality control of the dry-curing process in Iberian ham is performed with an olfactory evaluation by ham experts. The present study proposes to monitor the dry-curing process of Iberian ham using an objective analytical methodology that involves non-destructive sampling of the subcutaneous fat of the hams and a volatile profile analysis using gas chromatography-ion mobility spectrometry. Thirty-eight 100% Iberian acorn-fed hams were examined in total, with eighteen hams monitored during the post-salting stage and twenty during the drying-maturation stage. A total of 164 markers were detected in the samples monitored during the post-salting stage, whereas 276 were detected in the hams monitored during the drying-maturation stage. The study of the trends observed in the intensities of the markers throughout the curing process enabled the detection of potential indicators of the end of the post-salting stage. Thus, representative intensity thresholds were established for some markers (3-methylbutanal, pentanal, hexanal, (E)-octen-2-al, 2-hexen-1-ol and heptan-1-ol) to determine the optimal point to specify the end of the post-salting process for hams. These findings provide an objective tool to support the traditional sensory evaluation currently performed in the industry.

Volatile Profile of Bee Pollens: Optimization of Sampling Conditions for Aroma Analysis, Identification of Potential Floral Markers, and Establishment of the Flavor Wheel.

The volatile profile of bee pollen samples from Central and Eastern Europe was investigated by headspace solid phase microextraction (HS-SPME) combined with gas chromatography-mass spectrometry-olfactometry (GC-MS-O). Sampling conditions were optimized for the extraction of volatiles. Pollen odorants were extracted with six different fiber coatings, five various extraction times, three diverse extraction temperatures and three differing desorption times. The most effective combination was the application of divinylbenzene/carboxen/polydimethylsiloxane (DVB/CAR/PDMS) fiber coating used at 60°C for 30 min for extraction and 1 min for desorption. The optimized method was applied to investigate the volatile profile of 14 pollen samples (three rapeseed, musk thistle, rock-rose, traveler's joy, dropwort, honey locust, sunflower, red poppy, phacelia, sweet cherry, wild blackberry, and dandelion). The volatile profiles of bee pollens were different and were crucially depended on botanical origin. The aroma activity of the samples was generated by 31.0%-48.3% of total volatiles. The number of the identified odorants were between 75 and 101 in the pollen samples by GC-MS, of which 26-42 were aroma-active. The volatile organic compounds (VOCs) were classified into 13 different chemical classes. In most pollen, fatty acids were the predominant volatiles (14.87%-50.58%), while in some samples esters were the most abundant odorants (4.09%-45.46%). Panelists confirmed the presence of six main sensory characteristics described as "green/sour", "fruity", "spicy/herbal", "earthy/mushroom", "sweet/baked/caramel/honey", and "floral" compounds. These results establish the flavor wheel suitable for the comprehensive sensory description of pollen pellets from individual plant species. All samples contained characteristic odorants that may help in their botanical identification.

Machine Learning for Predicting Zearalenone Contamination Levels in Pet Food.

Zearalenone (ZEN) has been detected in both pet food ingredients and final products, causing acute toxicity and chronic health problems in pets. Therefore, the early detection of mycotoxin contamination in pet food is crucial for ensuring the safety and well-being of animals. This study aims to develop a rapid and cost-effective method using an electronic nose (E-nose) and machine learning algorithms to predict whether ZEN levels in pet food exceed the regulatory limits (250 µg/kg), as set by Chinese pet food legislation. A total of 142 pet food samples from various brands, collected between 2021 and 2023, were analyzed for ZEN contamination via liquid chromatography-tandem mass spectrometry. Additionally, the "AIR PEN 3" E-nose, equipped with 10 metal oxide sensors, was employed to identify volatile compounds in the pet food samples, categorized into 10 different groups. Machine learning algorithms, including liner regression, k-nearest neighbors, support vector machines, random forests, XGBoost, and multi-layer perceptron (MLP), were used to classify the samples based on their volatile profiles. The MLP algorithm showed the highest discrimination accuracy at 86.6% in differentiating between pet food samples above and below the ZEN threshold. Other algorithms showed moderate accuracy, ranging from 77.1% to 84.8%. The ensemble model, which combined the predictions from all classifiers, further improved the classification performance, achieving the highest accuracy at 90.1%. These results suggest that the combination of E-nose technology and machine learning provides a rapid, cost-effective approach for screening ZEN contamination in pet food at the market entry stage.

The Effect of Honey Powder Addition on Chosen Quality Properties of Model Chicken Products.

The objective of our paper was to evaluate the effect of honey powder addition on the quality of model chicken products over 14 days of refrigerated storage. Three model chicken product variants were produced: C-control, HP1%, HP2%-with 1 or 2% of honey powder addition. The cooking loss, basic chemical composition, water activity, texture, color, lipid oxidation (TBARS and PDSC), microbiological and sensory quality, and volatile compounds profile were determined. The adverse changes in lipids were slower in products with honey powder added compared to control product, revealing lower TBARS index values and longer oxidation induction times. After 14 days of storage, HP2% products showed significantly lower (up to 50%) TBARS values than control products. Furthermore, honey powder addition reduced the growth of psychrotrophic and lactic acid bacteria for up to 14 days of storage in comparison to the control products. However, deterioration of the volatile compounds profile (presence of alcohols and sulfur compounds) and occurrence of storage odor and flavor had an impact on the poorer sensory desirability of the control and HP1% products. Additional research is necessary aiming to improve the sensory quality of products with honey powder addition.

Variations in volatiles of different Rosa spp. cultivated in Thailand

ABSTRACT Rose is a high-value crop that is cultivated globally, including in Thailand, where its cultivars have been developed to suit the country’s geographical conditions. Surprisingly, volatile profile studies of roses cultivated in Thailand have rarely been carried out. The volatiles of the major cultivated roses, i.e. Mon Klai Kangwon (MK), Mon Dangprasert (MD) and Bishop’s Castle (BC) were profiled via HS-SPME-GC/MS. Phenyl ethanol was identified as the dominant volatile, particularly in BC. The signature rose scent of BC was attributed to citronellol, the Damask sweet and floral odour, and geraniol, a flowery rose-like odour. The volatile profile of the fresh and green rose scents was attributed to the fresh odour of 3-hexen-1-ol and 3-hexenyl acetate. Fragrance extracts in the formats of concretes that are applicable for fast-moving consumer goods were prepared. Phenyl ethanol was noted to be achieved in each cultivar. Sensory evaluation by healthy Thai male (22) and female (44) volunteers aged of 20.68 ± 2.08 years suggested that rose concrete is preferable for skin care. For the first time, the volatile profiles of roses cultivated in Thailand were authenticated. Innovative uses of rose fragrance in cosmetics align with current lifestyle and consumer demand are therefore to be encouraged.

Volatile Byproducts of Carotenoid Degradation as Biomarkers of Maize Infestation by the Maize Weevil (Sitophilus zeamais) (Motsch.).

Maize (Zea mays) is a major global food crop and a source of industrial raw materials. Effective postharvest storage is important for national food security programs, international trade, and global agriculture economics. The maize weevil (Sitophilus zeamais) is a primary postharvest insect pest that infests maize during storage and leads to significant losses. Using multivariate discriminant analysis of volatile profiles collected from intact and infested maize, we identified two volatile apocarotenoids, 6-methyl-5-hepten-2-one and 6-methyl-5-hepten-2-ol, as indicators of maize weevil infestation in stored maize. Emission of these biomarker compounds rapidly signaled maize weevil infestation and showed a significant correlation with oviposition damage to the stored kernels. The pattern of elevated biomarker emission after weevil exposure was consistent across all seven maize lines examined. These volatile biomarkers can be used for early detection and removal of infested maize and can aid in the control of this pest.

Characterization of the aromatic profile of Ruché wine from Piedmont (Italy) with gas chromatography-mass spectrometry and unsupervised machine learning techniques.

The volatile composition of Ruché, a red wine produced from a native grape in Piedmont (Italy), was investigated using headspace-solid phase microextraction (SPME) coupled to gas chromatography-mass spectrometry (GC/MS). The main volatile compounds of the wine were identified and quantified. Chemometric techniques were applied to identify features and possible clusters among the different samples. Forty volatile compounds were unambiguously identified in the 36 wine samples from different producers. The aroma profile was mainly composed of different alcohols and esters but also featured appreciable concentrations of terpenes, aldehydes, and octanoic acid. 2-Methyl benzaldehyde was identified for the first time. A high concentration of isoamyl alcohol significantly contributed to the aroma complexity. Differences between producers are highlighted. The present work is the first report about the volatile profile of Ruché wines investigated by chemometric methods with quantitative results. Multivariate exploratory approaches revealed minor but distinct differences among the studied wines, likely attributable to variations in winemaking procedures. This study could be developed in future by investigating possible differences between wines according to different production vintages. © 2024 The Author(s). Journal of the Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Effect of Pretreated Yellow Split Pea Flour Supplementation on Dough Rheology, Texture, Volatile Profile, and Sensory Attributes of Wheat Flour–Based Breads

Effect of Pretreated Yellow Split Pea Flour Supplementation on Dough Rheology, Texture, Volatile Profile, and Sensory Attributes of Wheat Flour–Based Breads

Characterization of Microbial Community and Flavor Compounds in Traditional Fermented Douchi Using HTS and HS-SPME-GC-MS.

This study aim is to elucidate the relationship between the microbial community dynamics and the production of volatile flavor compounds during the fermentation process of bacterial-type Douchi. Using high-throughput sequencing (HTS) and headspace solid-phase microextraction, gas chromatography-mass spectrometry (HS-SPME-GC-MS) was used to investigate microbial diversity and volatile compound profiles at different fermentation stages. Spearman correlation analysis was employed to identify potential associations between microbial genera and flavor compounds. The results revealed that the dominant bacterial phyla were Pseudomonadota and Firmicutes, with the dominant genera being Bacillus, Enterobacter, and Weissella. The dominant fungal phyla were Ascomycetes and Mucoromycota, whereas the dominant genera were Aspergillus, Trastula, and Pythium. A total of 110 volatile substances (relative to a relative content ≥ 0.03%) were detected during the fermentation process of bacterial-type Douchi. These included 34 hydrocarbons, 17 alcohols, 11 heterocyclic compound, 10 acids, 9 ketones, 9 esters, 6 aldehydes, 6 sulfur compounds, and 8 other compounds. The characteristic flavor compounds identified were ethanolamine, 2,3-butanediol, benzoaldehyde, 3-hydroxy-2-butanone, pterin-6-carboxylic acid, ethyl heptanoate, and diallyl disulfide. Correlation analysis indicated a strong positive association between benzoin aldehyde and pterin-6-carboxylic acid with the genera Thiobacillus and Pythium. Ethyl heptanoate was positively correlated with Enterobacter, Weissella, and Trasmium. Additionally, 3-hydroxy-2-butanone was positively correlated with the genus Staphylococcus. This research provides valuable insights into the microbial and chemical dynamics of bacterial-type Douchi fermentation, offering guidance for optimizing fermentation processes to improve product quality.