Determination of Volatiles and Carotenoid Degradation Compounds in Red Pepper Fermented by Lactobacillus parabuchneri

Discrimination and characterization of volatile organic compounds and nutritional values of three varieties of chopped pepper seeds

Fermented-chopped pepper is a widely consumed condiment in China due to its attractive flavor. Chopped pepper seed (CPS) is the byproduct generated during the production of chopped pepper and is generally discarded as waste. In this study, the volatile organic compounds (VOCs) and nutritional value of three varieties of CPS were investigated. Results indicated that the nutritional compositions of the three CPS varieties exhibited significant differences. All CPS samples contained 17 amino acids and were rich in fatty acids, with unsaturated fatty acids being predominant and accounting for 79 % of the total fatty acids. A total of 53 VOCs were identified by gas chromatography-ion mobility spectrometry, which could be classified into 9 groups, with aldehydes, esters, and alcohols comprising the three largest groups. The three varieties of CPS had remarkably varied aromas whereas there are five key VOCs (i.e., 2-pentylfuran, methional, ethyl 3-methylbutanoate, dimethyl disulfide, and nonanal) in all CPS samples. Network correlation analysis revealed that VOCs are closely correlated with amino and fatty acids. Thus, this study provides a useful basis for understanding the nutritional values and flavor characteristics of different CPS varieties, which could be used as an ingredient and might have great potential in the food industry.

Effect of Sichuan Pepper (Zanthoxylum genus) Addition on Flavor Profile in Fermented Ciba Chili (Capsicum genus) Using GC-IMS Combined with E-Nose and E-Tongue

This study examined the flavor profiles of fermented Ciba chili, comparing samples with Sichuan pepper (HJ) to those without Sichuan pepper (CK), using three analytical techniques: E-tongue, E-nose, and gas chromatography-ion mobility spectrometry (GC-IMS). The results obtained from the E-tongue and E-nose exhibited a clear difference in taste and flavor between CK and HJ. In detail, CK mainly exhibited a sour flavor profile, whereas HJ displayed an intricate and rich flavor. The HS-GC-IMS results identified a total of 60 compounds in the samples, with terpenes, alcohols, and esters being the primary volatile flavor compounds. Additionally, Zanthoxylum was found to significantly enhance the concentration of these compounds in fermented Ciba chili. Through robust principal component analysis (rPCA), 17 distinct flavor compounds were selected. Correlation analysis revealed that most terpenes exhibited positive correlations with LY2/LG, LY2/gCT1, LY2/Gct, LY2/G, LY2/Gh, and terpenes were found in higher concentrations in HJ. This study contributes a theoretical basis and provides data support for optimizing the fermentation process and elucidating the underlying mechanism of characteristic aroma formation in Ciba chili after fermentation.

Analysis of Important Volatile Organic Compounds and Genes Produced by Aroma of Pepper Fruit by HS-SPME-GC/MS and RNA Sequencing

Pepper is an important condiment, and its aroma affects its commercial value. In this study, transcriptome sequencing and combined headspace solid-phase microextraction and gas chromatography-mass spectrometry (HS-SPME-GC-MS) were used to analyze the differentially expressed genes and volatile organic compounds in spicy and non-spicy pepper fruits. Compared with non-spicy fruits, there were 27 up-regulated volatile organic compounds (VOCs) and 3353 up-regulated genes (Up-DEGs) in spicy fruits. The results of KEGG enrichment analysis of the Up-DEGs combined with differential VOCs analysis showed that fatty acid biosynthesis and terpenoid biosynthesis may be the main metabolic pathways for aroma differences between non-spicy and spicy pepper fruits. The expression levels of the fatty acid biosynthesis-related genes FAD, LOX1, LOX5, HPL, and ADH and the key terpene synthesis gene TPS in spicy pepper fruits were significantly higher than those in non-spicy pepper fruits. The differential expression of these genes may be the reason for the different aroma. The results can provide reference for the development and utilization of high-aroma pepper germplasm resources and the breeding of new varieties.

Study on the quality formation mechanism of Zao chili with enhanced fermentation by Lactipllantbacillus plantarum 5-1

Zao Chili (ZC) is a traditional fermented pepper, which plays an important role in Chinese cooking. The aim of this study was to elucidate the effect of Lactipllantbacillus plantarum 5-1 on the physicochemical properties, metabolite and microbiota profiling of ZC. The physicochemical factors changed regularly with the fermentation time. In the microbial communities, Lactobacillus, Weissella, Enterobacter, Gibberella, Fusarium, Zygosaccharomyces and Pichia were the dominant genera. 7 kinds of organic acids were detected in the whole fermentation process of ZC, but only 5 kinds changed significantly. Based on the OPLS-DA model with VIP > 1 and ANOVA with P < 0.05, 33 volatile flavor compounds with significant differences were screened out of 89. According to the redundancy analysis (RDA), fungi mainly contributed to soluble solids, while bacteria mainly contributed to pH. Lactobacillus, Weissella, Enterbacter and Zygosaccharomyces may be the potential flavor contributing microorganisms in the fermentation process of ZC by the Spearman correlation coefficient. A total of 11 main metabolic pathways were obtained by KEGG enrichment analysis of 89 volatile flavor compounds and 7 organic acids. Therefore, this study further enhanced our understanding of the flavor quality formation mechanism of Lactipllantbacillus plantarum in ZC, and providing a theoretical basis for improving the flavor quality of ZC.

Beneficial Effects of Fermentation of Red Chili Pepper Using Lactococcus lactis subs. Cremoris RPG-HL-0136 in High-Fat Diet-Induced Obese Mice

Red chili pepper is a beneficial natural spicy food that has antiobesity and antitype II diabetes effects, but it is not conducive to in-depth research as a dietary strategy to treat obesity. This study aims to investigate the beneficial effects of red chili pepper, fermented with a novel Lactococcus lactis subs. cremoris RPG-HL-0136. LC-MS/MS analysis is conducted to detect the content of capsaicin and dihydrocapsaicin, and no significant difference is observed between the nonfermented red chili pepper (NFP) (W/W) and the prepared L. lactis subs. cremoris RPG-HL-0136-fermented chili mixture (LFP). After establishing a high-fat diet-induced obese type II diabetic mouse model, the effects on weight gain, weight loss of liver and testicular fat, total cholesterol, triglyceride, fasting glucose, insulin, and homeostatic model assessment for insulin resistance in LFP were evaluated to be better than those in NFP following 10 weeks of interventions. All animal experiments were approved by the Institutional Animal Care and Use Committee of Xinxiang medical university. NFP and LFP could increase the expression of transient receptor potential vanilloid subfamily 1, peroxisome proliferator-activated receptor-alpha and caspase-2 in the high-fat mice. Compared with unfermented red chili pepper, the fermented red chili pepper complex significantly reduced LPS, tumor necrosis factor-alpha, and interleukin-6 in serum (P < .05). Intake of LFP significantly increased the expression of claudin-1 and occludin in the colon of the high-fat mice (P < .05), and there was no damage to the stomach and colon. This study provides scientific evidence that red chili pepper, fermented with L. lactis subs. cremoris RPG-HL-0136, may be beneficial for future treatment of obesity and accompanying diabetes. (IACUC.No.XYLL-20200019).

Correlation between microbial communities and key odourants in fermented capsicum inoculated with Pediococcus pentosaceus and Cyberlindnera rhodanensis

BACKGROUND

Fermented capsicum (i.e. pickled pepper) is one of the most popular fermented vegetables. However, the effect of inoculated microbial fermentation on pickled pepper is not yet fully understood.

RESULTS

Cyberlindnera rhodanensis J52 with a rich ester flavour and Pediococcus pentosaceus AL with a strong inhibitory effect on foodborne pathogenic bacteria were selected to prepare single- and double-strain fermented capsicum under low salt (< 10 g L^-1 sodium chloride) conditions. The inhibition zone of P. pentosaceus AL against Escherichia coli was up to 44 mm in diameter. Biochemical indicator analyses found that co-fermentation of P. pentosaceus AL and C. rhodanensis J52 changed the contents of vitamin C and short-chain fatty acids. Analysis of microbial diversity and volatile metabolome showed that 125 microbial species and 72 volatile compounds were detected, and P. pentosaceus was the dominant bacterium that inhibited the growth of other bacteria, while C. rhodanensis was the fungus that contributed the most to flavour. Correlation analysis between microorganisms and flavour compounds showed 725 correlations, and 124 microbial species may have participated in the formation of 69 compounds. Furthermore, 10 and 29 correlations were detected between P. pentosaceus AL or C. rhodanensis J52 and flavour compounds, respectively. Among them, 3-methyl-1-butanol acetate is speculated to be the main substance affecting the flavour of fermented capsicum by inoculation with C. rhodanensis J52.

CONCLUSION

The inoculation of P. pentosaceus and C. rhodanensis had a significant impact on the microbial community and volatile compounds of fermented capsicum and helped to improve its organoleptic qualities. © 2022 Society of Chemical Industry.

Microbial succession and its correlation with the dynamics of volatile compounds involved in fermented minced peppers

Fermented minced peppers are a traditional fermented food that has a unique flavor due to various microbial communities involved in fermentation. Understanding the changes in microbial communities and volatile components of fermented minced peppers is particularly important to unveil the formation of unique flavor of fermented peppers. In this study, the microbial communities and volatile compounds in fermented minced pepper was analyzed by high-throughput sequencing and GC-MS, as well as their underlying correlations were also established. Results indicated that 17 genera were identified as dominant microorganisms in the fermentation of minced pepper, accompanied by the detection of 64 volatile compounds. Further hierarchical clustering analysis (HCA) displayed that dynamic change of volatile metabolites were involved in the fermentation process, where alkane volatile components were mainly generated in the early stage (3–5 days), and alcohols volatile components were in the middle stage (7–17 days), while ester volatile components were mainly produced in both the early stage (3–5 days) and last stage (17–20 days). Bidirectional orthogonal partial least squares (O2PLS) analysis revealed that 11 genera were core functional microorganisms of fermented minced pepper. Cladosporium and Hansenpora were significantly correlated with the formation of 9 and 6 volatiles, respectively. These findings provide new insights into aroma profile variation of fermented minced peppers and underlying mechanism of characteristic aroma formation during fermentation.

Effect of fermentation of chosen vegetables on the nutrient, mineral, and biocomponent profile in human and animal nutrition

In the present study, the dry matter, crude ash, crude protein, ether extract, and energy, macro- (Na, K, Ca, Mg, P), micro- (Zn, Cu, Fe) minerals, heavy metals (Pb, Cd), vitamin C, A, carotene, and phenolic content were determined in chosen raw and fermented vegetables. The dietary intake of several macro- and microconstituents per one serving (100 g or humans and animals: ducks and pigs) was calculated. The fermentation process was found to reduce water and increase fat content in the vegetables. Lower levels of vitamin C and phenols were also found in the fermented vegetables. The vitamin A and carotene content in the fermented carrots and peppers were increased in comparison with the raw vegetables. The fermentation process decreased the concentration of some basic nutrients, mineral content, vitamins C and A, and phenols. Broccoli, peppers, and red beet had the highest levels of the analyzed nutrients and bioconstituents. The fermentation process is regarded by nutritionists as beneficial to human health. The addition of fermented plants is recommended in animal nutrition as well. This process modifies the chemical composition of preserved vegetables, e.g. it reduces the concentration of dietary fiber, and brings favorable effects in poultry and pig nutrition.

Influence of Drying Type of Selected Fermented Vegetables Pomace on the Natural Colorants and Concentration of Lactic Acid Bacteria

Nowadays, foods with probiotic bacteria are valuable and desired, because of their influence on human gut and health. Currently, in the era of zero waste, the food industry is interested in managing its waste. Therefore, the aim of the study was to determine the influence of drying process on the physicochemical properties of fermented vegetable pomace. The work included examining the influence of the lactic acid bacteria (Levilactobacillus brevis, Lactiplantibacillus plantarum, Limosilactobacillus fermentum and its mixture in the ratio 1:1:1) used for vegetable fermentation (beetroot, red pepper, carrot), obtaining pomace from fermented vegetables, and then selection of drying technique using the following methods: convection drying (CD) or freeze-drying (FD) on the physical and chemical properties of pomace. In the obtained pomace and its dried form, dry substance, water activity, color, and active substances such as betalains and carotenoids by spectrophotometric method and also bacteria concentration were evaluated. After fermentation of pomace from the same vegetable, a similar concentration of lactic acid bacteria was found as well as dry substances, color and colorants. Results of physico-chemical properties were related to the used vegetable type. After drying of pomace, it could be seen a high decrease in bacteria and colorant concentration (betalains, carotenoids) independently from drying and vegetable type as well as used starter cultures. The smallest change was observed for spontaneously fermented vegetables compared to those in which the starter culture was used.

Contribution of autochthonous yeasts with probiotic potential to the aroma profile of fermented Guajillo pepper sauce

BACKGROUND

Three yeast strains with probiotic potential, Hanseniaspora opuntiae, Pichia kudriavzevii, and Wickerhamomyces anomalus were inoculated in the fermentation of Guajillo chilli pepper (Capsicum annuum L.) sauce, and the different aroma profiles were investigated. Using headspace solid-phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS) analysis and gas chromatography-olfactometry (GCO), flavour compound production was evaluated during the fermentation of the Guajillo chilli pepper sauces.

RESULTS

A total of 78 volatile compounds were identified during the yeast fermentation of the sauce. Most aldehydes and terpenes detected were present at the beginning of the fermentation, indicating a Guajillo chilli pepper origin. Among the 34 active aroma compounds detected by GCO, propanoic acid (cheesy), 3-methylbutanoic acid (sharp, cheese), ethyl 2-methylbutanoate (fruity), and 6-methyl-5-hepten-2-one (strong, citrus) were identified as key aroma contributors produced by the inoculation of the yeasts. A different aroma profile was produced by probiotic yeast. Hanseniaspora opuntiae produced an aroma profile with herbal and green notes based on high production of aldehydes, ketones, and acetic acid. Pichia kudriavzevii and W. anomalus produced fruity, green-herbal, and cheesy notes based on ester compounds, alcohol and branched-chain acids production although, the production of propanoic acid by W. anomalus increased the cheesy character in the sauces.

CONCLUSION

The aroma profile of fermented chilli pepper sauces depends not only on the chili pepper varieties used but also on the fermentation process as a source of aroma compounds. The use of probiotic yeast can be used to improve and diversify the aroma profile of fermented chilli pepper sauces. © 2020 Society of Chemical Industry.

Comprehensive investigation on volatile and non-volatile metabolites in broccoli juices fermented by animal- and plant-derived Pediococcus pentosaceus

A metabolomics approach was employed to investigate differences and correlations among key odorants and non-volatile metabolites in broccoli juices fermented by plant- and animal-derived Pediococcus pentosaceus. Forty volatile metabolites were identified by headspace solid-phase microextraction/gas chromatography-mass spectrometry. According to orthogonal projections to latent structures-differential analysis, 24 and 21 differential volatiles were detected after fermentation by plant- and animal-derived P. pentosaceus, respectively. The concentrations of 10 odorants (OAV ≥ 1) detected by gas chromatography-olfactometry changed significantly after fermentation by P. pentosaceus. Using ultrahigh-pressure liquid chromatography/quadrupole time-of-flight mass spectrometry, 49.47% of the non-volatile metabolites were classified as lipids and lipid-like molecules. The relative expressions of five non-volatile metabolites that exhibited significant correlations with odorants using Spearman correlation analysis changed significantly after fermentation. Fermentation with animal- and plant-derived P. pentosaceus can therefore change key odorants and non-volatile metabolites in broccoli juice that contribute to the characteristic organoleptic properties of products.

Shifts in autochthonous microbial diversity and volatile metabolites during the fermentation of chili pepper (Capsicum frutescens L.)

To reveal the potential of core bacterial and fungal communities for aroma formation in the fermentation of chili pepper, shifts in microbial diversity and volatile metabolites during the 32-day fermentation process were measured using high-throughput sequencing and gas chromatography-mass spectrometry. Rosenbergiella and Staphylococcus were the dominant bacterial genera, where Hyphopichia and Kodamaea were the most abundant fungi, in fermented chili pepper. Sixteen differential volatile metabolites were detected in fermented and unfermented samples using differential metabolomics analysis. Nine strains from the genera Hyphopichia, Staphylococcus, Rosenbergiella, and Bacillus were isolated from fermented chili pepper. The correlation of dominant microorganisms with key odorants by Spearman correlation and two-way orthogonal partial least squares analysis indicated that Hyphopichia exhibited a significant positive correlation with the formation of 11 key odorants. These findings enhance our understanding of the core functional bacterial and fungal genera involved in the production of desirable flavors in fermented chili pepper.

Physicochemical, microbial, and aroma characteristics of Chinese pickled red peppers (Capsicum annuum) with and without biofilm

Biofilm formation in the production of fermented vegetable might impact its quality and safety. In this study, physicochemical and microbial properties, volatile and aroma-active compounds between PRPs without biofilm (NPRP) and with biofilm (FPRP) were investigated by gas chromatography-mass spectrometry, gas chromatography-olfactometry, aroma extract dilution analysis, and spiking tests. The pH and titratable acidity were 3.66 ± 0.00 and 0.47 ± 0.08 g/100 g lactic acid in NPRP and 3.48 ± 0.01 and 0.87 ± 0.10 g/100 g lactic acid in FPRP, respectively. The nitrite level of the two PRPs was 1.87–1.92 mg kg⁻¹, which was below the limited value (20 mg kg⁻¹) of fermented vegetables regulated by the GB2760-2017. FPRP had relatively higher microbial and yeast numbers than NPRP, three common pathogens, namely, Salmonella spp., Staphylococcus aureus, and Shigella spp. were not detected. A total of 70 and 151 aroma compounds were detected in NPRP and FPRP, respectively, including 13 classes of compounds. The dominant aroma attributes of FPRP were sour, floral, mushroom-like, green, and smoky, while NPRP exhibits a mushroom-like flavor. Acetic acid, ethanol, α-terpineol, (E)-2-nonenal, 2-heptanol, phenylethyl alcohol, and linalool were potent key aroma-active compounds in NPRP and FPRP. Results of spiking tests showed that the addition of each substance not only increased its own odour, but also had significant effects on other smells. FPRP displayed richer varieties and contents of aroma profile than NPRP. However, some compounds, such as 4-ethylguaiacol and 4-vinylguaiacol, which were only detected in FPRP, had negative roles on the aroma attributes.

The aroma profile of PRPs was evaluated by GC-MS, GC-O, AEDA, OVA and spiking test. Biofilm can improve the variety and contents of aroma.

PacBio sequencing reveals bacterial community diversity in cheeses collected from different regions

Cheese is a fermented dairy product that is popular for its unique flavor and nutritional value. Recent studies have shown that microorganisms in cheese play an important role in the fermentation process and determine the quality of the cheese. We collected 12 cheese samples from different regions and studied the composition of their bacterial communities using PacBio small-molecule real-time sequencing (Pacific Biosciences, Menlo Park, CA). Our data revealed 144 bacterial genera (including Lactobacillus, Streptococcus, Lactococcus, and Staphylococcus) and 217 bacterial species (including Lactococcus lactis, Streptococcus thermophilus, Staphylococcus equorum, and Streptococcus uberis). We investigated the flavor quality of the cheese samples using an electronic nose system and we found differences in flavor-quality indices among samples from different regions. We found a clustering tendency based on flavor quality using principal component analysis. We found correlations between lactic acid bacteria and the flavor quality of the cheese samples. Biodegradation and metabolism of xenobiotics, and lipid-metabolism-related pathways, were predicted to contribute to differences in cheese flavor using Phylogenetic Investigation of Communities by Reconstruction of Unobserved States (PICRUSt). This preliminary study explored the bacterial communities in cheeses collected from different regions and their potential genome functions from the perspective of flavor quality.

Investigation on the Interaction Behavior Between Oenothein B and Pepsin by Isothermal Titration Calorimetry and Spectral Studies

Oenothein B (OeB) is a dimeric macrocyclic ellagitannin isolated from Herbs and fruits that have a variety of biological activities. In order to better understand the effect of OeB on the activity of the digestive enzyme pepsin, interactions between OeB and pepsin were investigated in vitro under simulated physiological conditions based on enzyme inhibition studies, fluorescence, isothermal titration calorimetry, CD, and molecular docking. It was found OeB is an effective inhibitor of pepsin, likely acting in a reversible manner through both competitive and noncompetitive inhibition. Fluorescence quenching of pepsin by OeB was a static quenching. CD spectra showed the addition of OeB causes the main chain of pepsin to loosen and expand and the partial β-sheet structure to be converted to a disordered structure. Isothermal titration calorimetry and docking studies revealed the main binding mechanism of OeB and pepsin was through noncovalent interactions, hydrophobic interactions with OeB and the internal hydrophobic group of pepsin, and then hydrogen bonding between OeB and the Val243 and Asp77 residues of pepsin. Noncovalent bonds between OeB and pepsin change the polarity and structure of enzymes, decreasing enzymatic activity. Compared with small molecular polyphenols, OeB has a weaker hydrophobic interaction with pepsin and less effect on the secondary structure of pepsin. These findings are the first direct elucidation of the interactions between the oligomer ellagitannin OeB and pepsin, further contributing to understanding binding between oligomer ellagitannins and digestive enzymes. PRACTICAL APPLICATION: The results of this study indicate that the interaction between OeB and pepsin has a certain inhibitory effect on pepsin. In order to reduce the impact of OeB on human digestion and its own activities, nano-encapsulation technology can be used in the future to protect oligomeric ellagitannin such as OeB.