Lactic Acid Bacteria Fermentation Research Articles

Effective bioconversion of 1,3-propanediol from biodiesel-derived crude glycerol using organic acid resistance–enhanced Lactobacillus reuteri JH83

Organic acids produced during the fermentation of lactic acid bacteria inhibit cellular growth and the production of 1,3-propanediol (1,3-PDO). Lactobacillus reuteri JH83, which has an increase of 18.6% in organic acid resistance, was obtained through electron beam irradiation mutagenesis irrelevant to the problem of genetically modified organisms. The maximum bioconversion of 1,3-PDO in fed-batch fermentation using pure glycerol by L. reuteri JH83 was 93.2 g/L at 72 h, and the productivity was 1.29 g/L·h, which achieved an increase by 34.6%, compared to that of the wild-type strain. In addition, the result of fed-batch fermentation for the production of 1,3-PDO using crude glycerol was not significantly different from that of pure glycerol. Additionally, transcriptome analysis confirmed changes in the expression levels of sucrose phosphorylase, which is a major facilitator superfamily transporter, and muramyl ligase family proteins, which protect lactic acid bacteria from various stressors, such as organic acids.

Effect of two-step fermentation with lactic acid bacteria and Saccharomyces cerevisiae on key chemical properties, molecular structure and flavor characteristics of horseradish sauce

To enhance the quality or, in other words, increase the variety of horseradish sauce, two-step fermentation using lactic acid bacteria (LAB) and Saccharomyces cerevisiae is proposed for the production of the sauce. Total phenolics, acids and amino acid nitrogen contents were determined and used to assess the fermentation efficiency, while antioxidant activities, profiles of amino acids and volatile flavor compounds was used to indicate the quality of the sauce. Molecular structure determination as well as electronic tongue and sensory analyses were also conducted. Adding S. cerevisiae after 48 h of LAB fermentation resulted in higher fermentation efficiency. The sauce was noted to be fermented more fully, with increased content of amino acids by 23.10% compared with unfermented samples; its DPPH radical scavenging ability and reducing power increased by 26.26% and 33.33%, respectively. The contents of alcohols, esters and acids increased in the sauce. The electronic tongue and sensory evaluation showed that the sauce had good sensory quality.

Influence of Fermentation of Pasteurised Papaya Puree with Different Lactic Acid Bacterial Strains on Quality and Bioaccessibility of Phenolic Compounds during In Vitro Digestion.

This study describes the impact of utilising different strains of lactic acid bacteria (LAB) for the fermentation of papaya puree and their effect on the quality parameters and bioaccessibility of phenolic compounds during simulated in vitro gastrointestinal digestion. Papaya was processed into puree; pasteurised and fermented at 37 °C for 2 days; and stored for 7 days at 4 °C using LAB strains Lactiplantibacillus plantarum 75 (L75*D2; L75*D7), Weissella cibaria 64 (W64*D2; W64*D7) and Leuconostoc pseudomesenteroides 56 (L56*D2; L56*D7), respectively. Non-fermented samples at 0 (PPD0), 2 (PPD2) and 7 days (PPD7) served as controls. pH was reduced with fermentation and was lowest in L56*D2 (3.03) and L75*D2 (3.16) after storage. The colour change (ΔE) increased with the fermentation and storage of purees; L75*D7 showed the highest ΔE (13.8), and its sourness reduced with storage. The fermentation by W64*D7 and L75*D7 increased the % recovery of chlorogenic, vanillic, syringic, ellagic, ferulic acids, catechin, epicatechin and quercetin in the intestinal fraction compared to the L56*D7 and PPD7. Fermentation by W64*D7 and L75*D7 significantly improved the antioxidant capacity of the dialysed fraction compared to the L56*D7 or PPD7. L56*D7-fermented papaya puree showed the highest inhibitory effect of α-glucosidase activity followed by L75*D7. L75*D7 had a significantly higher survival rate. LAB fermentation affected the bioacessibilities of phenolics and was strain dependent. This study recommends the use of Lpb. plantarum 75 for fermenting papaya puree.

Effect of different lactic acid bacteria on nitrite degradation, volatile profiles, and sensory quality in Chinese traditional paocai

Paocai is one of the most popular traditional fermented products in China. Different lactic acid bacteria (LAB) have an important influence on the microbial changes, the dynamic changes of metabolites, and the sensory qualities of paocai. In this study, five different paocai groups were designed which were fermented by Lactobacillus plantarum DMDL 9010 (LP), Lactobacillus brevis GIM 1.773 (LB), Leuconostoc mesenteroides GIM 1.774 (LM), mixed three kinds of LAB (LP + LB + LM), pasteurization (PST) and natural fermentation (NF) without LAB. The nitrite, nitrate, pH, titratable acidity, viable count (LAB and yeast) and metabolites (organic acids, sugars and volatile substances) of these paocai groups were measured. Compared with each single bacterial fermentation (LP, LB and LM), NF and PST, the mixed three kinds of LAB (LP + LB + LM) had a lower nitrite peak, which could be attributed to the significant accumulation of organic acids, and positively affected sensory quality of paocai. Flavor substances produced in paocai samples confirmed as alcohols, ketones and olefins. Sensory evaluation showed that multi-bacteria mixed fermentation of paocai had a better flavor than that of NF, PST and single bacterial fermentation. Therefore, the use of multiple LAB as starter cultures contributes to enhance paocai qualities and control the levels of nitrite.

Influence of Lactic Acid Bacteria Fermentation on Physicochemical Properties and Antioxidant Activity of Chickpea Yam Milk

This study aimed to evaluate the influence of lactic acid bacteria fermentation on the physicochemical properties and antioxidant activity of chickpea yam milk. Four groups of chickpea milk were prepared through fermentation with lactic acid bacteria for quality and functionality improvement. Results indicate that the polysaccharide content of four samples declines during the fermentation process, and their infrared spectrums are similar with a slight difference in the transmittances of some characteristic bands. The sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) profiles of four samples with 24 h fermentation showed a band disappearance in the range of 94.3 KDa and generation of many small-molecule peptides, revealing the protein degradation during fermentation. The moderate enzymatic hydrolysis had no adverse effect on the texture and color of the samples. A substantial increase in DPPH, ABTS radical scavenging rates, and FRAP value was observed after 12 h fermentation, especially the CPBY sample. The present results indicate that lactic acid bacteria fermentation can be used to improve the physicochemical properties of samples and enhance their antioxidant activity.

A rapid screening method to evaluate acidifying activity by lactic acid bacteria

The determination of pH in fermented milk is an important parameter for monitoring the production of acid by lactic acid bacteria (LAB). In this work, a colorimetric method is proposed that allows a fast determination of LAB acidification ability by evaluation of pH drop in whey fermentation. The proposed method uses spectrophotometry to measure the pH change by bacteria and uses bromocresol purple as a pH indicator dye. The absorbance at 430 nm of a buffer solution with bromocresol purple was found to be correlated with pH values. This colorimetric assay was linear within the pH range of 4.6–7.0. Upon regression analysis, linear equation y = −0.1267× + 0.9196 was obtained having r2 value of 0.9927. The assay was validated by the use of LAB fermentation in sweet whey and comparison to the values obtained by glass electrode/pH meter. Estimation of acidification activity of LAB in whey was found to be similar in both methods (r = 0.801, p > 0.05). The proposed procedure presents a viable alternative to the measurement of pH by the standard method and allows the simultaneous and fast screening of LAB acidifying activity.

Production of Phenyllactic Acid from Porphyra Residues by Lactic Acid Bacterial Fermentation

The concept of algae biorefinery is attracting attention because of the abundant valuable compounds within algal biomass. Phenyllactic acid (PhLA), a broad-spectrum antimicrobial organic acid that can be produced by lactic acid bacteria (LAB), is considered a potential biopreservative. In this study, a cascading biorefinery approach was developed to harvest PhLA from Porphyra residues by LAB fermentation. LAB strains were cultivated in de Man, Rogosa and Sharpe (MRS) broth to screen their ability to produce PhLA. As the strains of Lactobacillus plantarum KP3 and L. plantarum KP4 produced higher concentrations of PhLA at 0.09 mg/mL, these two strains were employed for fermentation. After phycobiliprotein extraction, the Porphyra residues, ultrafiltration eluate, phenylalanine (Phe) and yeast extract with a volume of 20 mL were inoculated with LAB strain KP3 and fermented at 37 °C for 120 h. The PhLA content of the fermented broth was 1.86 mg. To optimize the biorefinery process, the ultrafiltration eluate was replaced by commercial cellulase. Up to 4.58 mg of PhLA, which was 2.5 times greater than that produced from KP3 cultured in MRS broth, could be harvested. Taken together, the findings provide an optimized process for LAB fermentation, which is shown to be a feasible algae biorefinery approach to obtaining PhLA from Porphyra residues.

Physicochemical Parameters and Bioaccessibility of Lactic Acid Bacteria Fermented Chayote Leaf (Sechium edule) and Pineapple (Ananas comosus) Smoothies.

In this study, popularly consumed traditional chayote leaves and locally produced pineapple fruit were used to develop a fermented smoothie using lactic acid bacteria (LAB) strains: Lactobacillus plantarum (L75), Weissella cibaria (W64), and their combination (LW64 + 75). The physicochemical parameters [pH, total soluble solids (TSS), and color], total phenols, and carotenoid contents of the smoothies fermented for 48 h and stored for 7 days at 4°C were compared with the unfermented (control) smoothies. Results indicated that LAB fermentation reduced the pH from 3.56 to 2.50 after 48 h (day 2) compared with the non-fermented smoothie at day 2 (pH 3.37). LAB strain L75 significantly reduced the TSS content of the smoothies to 13.06°Bx after 2 days of fermentation. Smoothies fermented by L75 showed overall acceptability after 7 days of storage compared with the non-fermented puree on day 0. The LW64 + 75 significantly reduced the color change (ΔE), which was similar to the control. L75 increased the phenolic content, and W64 enhanced the total carotenoid content of the smoothies after 2 days of fermentation compared with other treatments. The use of an in vitro model simulating gastrointestinal (GI) digestion showed that fermentation with L75 improved the total phenol recovery by 65.96% during the intestinal phase compared with the control. The dialysis phase mimicked an epithelial barrier, and 53.58% of the recovered free soluble are bioavailable from the L75 fermented smoothies compared with the control. The antioxidant capacity of dialyzable fraction of the L75 fermented smoothie was significantly higher than that of the control and smoothies fermented with W64 or LW64 + 75.

Succession of Bacterial Community During the Initial Aerobic, Intense Fermentation, and Stable Phases of Whole-Plant Corn Silages Treated With Lactic Acid Bacteria Suspensions Prepared From Other Silages.

The present study was aimed at investigating the bacterial community in lactic acid bacteria (LAB) suspensions prepared from whole-plant corn silage (LAB suspension-CS) and Elymus sibiricus silage (LAB suspension-ES) and the bacterial community succession of whole-plant corn silages inoculated with LAB suspension-CS or LAB suspension-ES during initial aerobic phase, intense fermentation phase, and stable phase. The LAB suspensions were cultured in sterile Man, Rogosa, Sharpe broth at 37°C for 24 h and used as inoculants for ensiling. The chopped whole-plant corn was treated with distilled water (CK), LAB suspension-CS (CSL), or LAB suspension-ES (ESL) and then ensiled in vacuum-sealed plastic bags containing 500 g of fresh forage. Silages were sampled at 0 h, anaerobic state (A), 3 h, 5 h, 10 h, 24 h, 2 days, 3 days, 10 days, 30 days, and 60 days of ensiling with four replicates for each treatment. The results showed that Lactobacillus, Weissella, and Lachnoclostridium_5 dominated the bacterial community in LAB suspension-CS; Lactobacillus was the most predominant bacterial genus in LAB suspension-ES. During the initial aerobic phase (from 0 h to A) of whole-plant corn silage, the pH and the abundances of Pantoea, Klebsiella, Rahnella, Erwinia, and Serratia increased. During the intense fermentation phase (from A to 3 days), the pH decreased rapidly, and the microbial counts increased exponentially; the most predominant bacterial genus shifted from Pantoea to Weissella, and then to Lactobacillus; inoculating LAB suspensions promoted the bacterial succession and the fermentation process, and LAB suspension-CS was more effective than LAB suspension-ES. During the stable phase (from 3 to 60 days), the pH and the microbial counts decreased, and Lactobacillus dominated the bacterial community with a little decrease. The results also confirmed the existence of LAB fermentation relay during fermentation process, which was reflected by Weissella, Lactococcus, and Leuconostoc in the first 5 h; Weissella, Lactococcus, Leuconostoc, Lactobacillus, and Pediococcus between 5 and 24 h; and Lactobacillus from 24 h to 60 days.

Research on Improvement Technology of Wet Grinding Process Based on L-Cysteine Fermentation Condition

To study the effects of wet milling, farm Corn; starch; gel filtration chromatography; wet milling; fermentation modification; extrusion enation modification of lactic acid bacteria and extrusion technology on the composition of starch in corn flour. Common corn varieties as a material, corn flour is prepared by wet milling, fermentation modification of lactic acid bacteria and extrusion puffing technology, and starch is extracted from corn flour, using Sepharose CL-2B, Agarose gel column chromatography was used to study the composition of starch. The GPC chart of wet-milled corn flour starch has a bimodal distribution, and the starch molecules are divided into macromolecules Branched-chain region (region I) and straight-branched mixed region (region II), the elution volume of region I is 21-42 ml, and the average molecular weight polymerization degree is 26 632-18 666,The elution volume of zone II is 42-70 ml, and the relative molecular weight average polymerization degree is 18 666-8 046; the starch GPC spectrum of fermented modified corn flour is also double peak Distribution, but the average molecular degree of polymerization of the two regions narrowed, and the starch composition changed; the GPC spectrum of extruded corn flour starch showed a single peak distribution, and the relative The average polymerization degree of the molecular weight is 27 960-9 374. [Conclusion] Starch molecules are degraded during fermentation and extrusion of lactic acid bacteria, and degradation occurs during fermentation The starch molecules are mainly the starch molecules between zone I and zone II, and the high temperature and high shear in the extrusion process make most of the starch molecules in zone I occur degradation.

Combined lactic fermentation and enzymatic treatments affect the antigenicity of β-lactoglobulin in cow milk and soymilk-cow milk mixture

This study evaluated the effect of lactic acid bacteria (LAB) fermentation combined with microbial transglutaminase (MTGase)-mediated modification on the antigenicity of β-lactoglobulin (β-LG) in cow milk and soymilk-cow milk mixture (SCMM). Results showed that MTGase-treatment could reduce the antibody binding reactivity of β-LG, especially in the SCMM (declined to 37.1% compared to cow milk), and had a further significant decrease to 9.9% (P < 0.01) in the presence of LAB. Moreover, LAB combined with MTGase (LAB + MTGase) treatment enhanced the cross-linking degree of β-LG, and the particle average size of aggregates formed in both cow milk and SCMM systems were also increased compared to LAB-treatment. Although the antigenicity of β-LG was not eliminated during in vitro digestion phases, our findings suggested that LAB + MTGase-treatment could be a much more efficient approach to reduce the antigenicity of β-LG in mixed soymilk-cow milk protein polymers compared to cow milk protein polymers.

The combined effect of fermentation of lactic acid bacteria and in vitro digestion on metabolomic and oligosaccharide profile of oat beverage

Oat (Avena sativa L.) is widely appreciated for its beneficial properties for human health, which have led to the introduction of more food products on the market, including oat beverages. The fibre components found in the oat are recognized for their beneficial effects, despite other bioactive compounds with healthy properties being present. This work aimed to evaluate the metabolites profile of a commercial oat beverage, either fermented with lactic bacteria or not, following in vitro gastro-intestinal digestion. UHPLC-QTOF untargeted metabolomics allowed investigation of the bioaccessibility of health-related metabolites from the oat beverage at the intestinal level. The results identified flavonoids, phenolic acids (avenanthramides), amino acids and steroids as the major classes of compounds. In particular, after in vitro digestion, amino acids, peptides, and phenolic acids showed the highest increases. The co-fermentation of oat milk by Lactobacillus spp. and Bifidobacterium spp. strains decreased the levels of both lignans and phytic acid, while increased the levels of some polyphenols like avenanthramides. Furthermore, fermentation by microorganisms increased the bioaccessibility of specific amino acids, vitamins, and polyphenols (flavonoids and phenolic acids). Interestingly, despite lacking a significant part of beta-glucans, the HPAEC-PAD profiling of our oat beverage evidenced that the fermentation process did not alter the oligosaccharides profile, thus preserving its prebiotic potential. The phytochemical profile of oat milk was shown to have a functional potential. Nonetheless, the fermentation by bacterial strains changed the profile of metabolites during in vitro digestion, thus offering an interesting option in the future development of cereal-based beverages.

Enriching the nutritive value of marigold (Tagetes erecta L) crop residues as a ruminant feed by lactic acid bacteria\xa0during ensilage

BackgroundMarigold (Tagetes erecta L) accounts for over half of the world’s loose flower production, and marigold crop residue (MCR) are abundantly available and should be used as a forage. In this study, MCR from the last commercial flower pickings was ensilaged with lactic acid bacteria (LAB) and the shift in their volatile organic compounds (VOCs) profiles was monitored. Samples were collected at 6 different times during ensilage (3, 6, 9, 12, 15, 30 days) to determine and quantify the VOCs changes using a solid-phase microextraction (SPME) technique and gas chromatography – mass spectrometry (GC-MS).ResultsAfter 30 days, the caryophyllene and piperitone, which account for 14.7 and 12.1% of total VOCs, decreased by 32.9 and 9.6% respectively, alcohols increased from 2.8 to 8.1%, and the acetic acid content increased by 560%.ConclusionWe have confirmed LAB can degrade the content of terpenes and enhance the content of alcohols and acids in MCR, which was for the first time on terpene degradation in fodder by ensilage. These results have shed light on our understanding of how to improve fodder odor and to enhance terpene degradation by lactic acid bacteria fermentation.

김치 유래 복합 종균 적용이 김치의 발효과정에 미치는 영향

In this study, we compared the changes in the quality of kimchi fermented with a complex starter and a single starter. Lactic acid bacteria strains isolated from kimchi were used as starters, and fermention was performed at 10°C for 26 days. The rate of reduction in lactic acid bacteria was low, the initial pH was maintained at a constant level, and the dominance rate of the starter was high at 83% on the 15th day of fermentation with the complex starter, compared to fermentation with the control and single starters. Regarding the CO2 and free sugar content, which are factors affecting product quality and are influenced by lactic acid bacteria fermentation, 1.4 and 1.5 times higher CO2 and mannitol production, respectively, were observed during fermentation of free sugars with the complex starter than in fermentation with the single starter. These results show that the use of a complex starter can improve the distribution quality of kimchi as it results in an extended shelf life and enhanced sensory quality.

Characteristic and Isoflavone Level of Soymilk Fermented by Single and Mixed Culture of &lt;i&gt;Lactobacillus plantarum &lt;/i&gt;and Yoghurt Starter

Fermented soymilk has better health benefits compared to unfermented soymilk. The health benefits of fermented soymilk are improving blood lipid profile, antioxidants and anti-inflammatory. Fermentation of lactic acid bacteria can increase the content of aglycon isoflavones, namely genistein and daidzein. The purpose of this study was to analyze the characteristics of soymilk and isoflavone level fermented with a single culture of Lactobacillus plantarum and mixed culture of Lactobacillus plantarum and yogurt starter. This research consisted of 4 treatments, namely unfermented, fermentation using L. plantarum, fermentation using S. thermophilus and L.bulgaricus, and fermentation using L. plantarum, S. thermophillus, L. bulgaricus. Samples analyzed proximate, titratable acid , pH, total lactic acid bacteria, total daidzein, genistein and sensory quality. The results showed that the total acid, pH, and total lactic acid bacteria for fermentation with mixed cultures were higher compared to L. plantarum single culture. Total daidzein and genistein for single culture and mixed culture were not significantly different between the two groups. Sensory analysis shows that soymilk with a single culture have the highest value for the parameters of taste, aroma and color.

Brewers\u2019 spent grain as substrate for dextran biosynthesis by Leuconostoc pseudomesenteroides DSM20193 and Weissella confusa A16

BackgroundLactic acid bacteria can synthesize dextran and oligosaccharides with different functionality, depending on the strain and fermentation conditions. As natural structure-forming agent, dextran has proven useful as food additive, improving the properties of several raw materials with poor technological quality, such as cereal by-products, fiber-and protein-rich matrices, enabling their use in food applications. In this study, we assessed dextran biosynthesis in situ during fermentation of brewers´ spent grain (BSG), the main by-product of beer brewing industry, with Leuconostoc pseudomesenteroides DSM20193 and Weissella confusa A16. The starters performance and the primary metabolites formed during 24 h of fermentation with and without 4% sucrose (w/w) were followed.ResultsThe starters showed similar growth and acidification kinetics, but different sugar utilization, especially in presence of sucrose. Viscosity increase in fermented BSG containing sucrose occurred first after 10 h, and it kept increasing until 24 h concomitantly with dextran formation. Dextran content after 24 h was approximately 1% on the total weight of the BSG. Oligosaccharides with different degree of polymerization were formed together with dextran from 10 to 24 h. Three dextransucrase genes were identified in L. pseudomesenteroides DSM20193, one of which was significantly upregulated and remained active throughout the fermentation time. One dextransucrase gene was identified in W. confusa A16 also showing a typical induction profile, with highest upregulation at 10 h.ConclusionsSelected lactic acid bacteria starters produced significant amount of dextran in brewers’ spent grain while forming oligosaccharides with different degree of polymerization. Putative dextransucrase genes identified in the starters showed a typical induction profile. Formation of dextran and oligosaccharides in BSG during lactic acid bacteria fermentation can be tailored to achieve specific technological properties of this raw material, contributing to its reintegration into the food chain.

Fermentation of amylolytic yeast and lactic acid bacteria to improve the quality of modified cassava

The amylolytic activity has been studied in yeast and lactic acid bacteria (LAB) which are isolated from various types of traditional fermented cassava. The study aimed to obtain yeast and LAB isolates which high amylolytic activity for inoculum in cassava fermentation. A total of 23 yeasts and 22 LAB isolates were isolated from Gatot, Tiwul, Tapai, and Cassava fermented using chloramphenicol yeast glucose (CYG) media for yeast and de Man Rogosa Sharpe agar (MRSA) + CaCO3 for LAB. Yeast amylolytic activity was tested using yeast extract peptone starch agar medium, while the amylolytic LAB used MRS + starch media with Lugol’s iodine indicator. Colonies showing clear zone areas were measured as amylase activity on the iodine complex method. Isolates that have the highest amylolytic activity were used as inoculum in cassava fermentation. Yeast Tr7 and LAB G6 isolates showed the highest amylolytic activity (0.0624 U/mL and 0.0627 U/mL). Cassava fermentation products using yeast Tr7 and BAL G6 resulted 52.06% of hydrogen cyanide (HCN) reduction higher than without inoculum (32.32%). According to biochemical identification using API 50 CHL kit, LAB G6 isolate was 99.6% identical with Pediococcys pentosaceus whereas biochemical identification using API 20 C AUX showed that yeast Tr7 was 95.8% identical with Candida tropicalis. The biochemical identification result was similar to the molecular identification result. In molecular identification using 28S rRNA sequence analysis revealed that yeast Tr7 was 99% similar with Candida tropicalis NITCSK13 strain. LAB G6 was 100% similar with Pediococcus pentosaceus BSS1375 strain using 16S rRNA sequence analysis. C. tropicalis Tr7 and P. pentosaceus G6 potentially used for inoculum in cassava fermentation process to improve cassava quality as a functional food.

Anti-aging effects of the fermented anthocyanin extracts of purple sweet potato on Caenorhabditis elegans.

Anthocyanins have anti-inflammatory, anticarcinogenic and antioxidant properties and anti-aging effects as well as potential application as pigments. The metabolism of anthocyanins in fermented food has attracted increasing attention. However, the effect of lactic acid bacteria (LAB) fermentation on its anti-aging activity remains mostly unknown. The current study aimed to investigate the compositions, antioxidant activities and anti-aging effect of fermented purple sweet potato anthocyanins (FSPA) on aging Caenorhabditis elegans compared to raw purple sweet potato anthocyanins (PSPA). Results showed that anthocyanins were degraded into more bioavailable phenolic acids by Weissella confusa fermentation. PSPA and FSPA can extend the lifespan of C. elegans by 26.7% and 37.5%, respectively, through improving the activity of antioxidant enzymes as well as decreasing MDA content, ROS levels and lipofuscin accumulation. Pretreatment of the worms with PSPA and FSPA induced their potential to resist to thermal tolerance and oxidative stress, and FSPA exerted a higher anti-stress effect than PSPA. Moreover, FSPA supplementation upregulated the mRNA expressions of genes daf-16, hsp-16.2, sir-2.1, skn-1 and sod-3 and downregulated the expression of daf-2 in the nematodes, whereas PSPA only induced the increase in the expressions of sir-2.1, skn-1 and sod-3. Overall, FSPA can improve stress resistance and extend the lifespan of C. elegans by both insulin/IGF-1 signaling pathway and dietary restriction pathway, providing a theoretical basis for the application of PSPA in fermented food as functional pigments.

Bioaccessibility and bioavailability of bioactive compounds from yellow mustard flour and milk whey fermented with lactic acid bacteria

Microbial fermentation with lactic acid bacteria (LAB) is a natural food biopreservation method. Yellow mustard and milk whey are optimum substrates for LAB fermentation. The aim of the present study was to evaluate the bioaccessibility and bioavailability of bioactive compounds from yellow mustard flour and milk whey both with and without LAB fermentation. All extracts were subjected to a simulated digestion process. Total polyphenols, DL-3-phenyllactic acid (PLA), lactic acid, and the antioxidant activity were determined in the studied matrices before and after simulated digestion. Yellow mustard flour was significantly richer in total polyphenols, whereas significantly higher concentrations of PLA and lactic acid were observed in milk whey. Similar antioxidant activity was determined in both ingredients being in all cases strongly reduced after in vitro digestion. Higher bioaccessibility was found for polyphenols and PLA in milk whey. Transepithelial transport of total polyphenols was higher in yellow mustard flour compared to milk whey, reaching bioavailability values between 3-7% and 1-2%, respectively. PLA transepithelial transport was only significant in both fermented matrices with bioavailability around 4-6%. Transepithelial transport of lactic acid reached values of 31-34% (bioavailability ∼ 22%) and 15-78% (bioavailability ∼ 3%) in milk whey and yellow mustard flour, respectively. LAB fermentation showed beneficial effects on enriching extracts with PLA, lactic acid, and antioxidant activity, as well as increasing bioaccessibility of these acids in yellow mustard flour and total polyphenol bioavailability in milk whey. Results pointed to yellow mustard flour and milk whey as natural preservative ingredients used in the food industry, especially when fermented with LAB.

Real-Time Monitoring of Yogurt Fermentation Process by Aquaphotomics Near-Infrared Spectroscopy.

Automated quality control could have a substantial economic impact on the dairy industry. At present, monitoring of yogurt production is performed by sampling for microbiological and physicochemical measurements. In this study, Near-Infrared Spectroscopy (NIRS) is proposed for non-invasive automated control of yogurt production and better understanding of lactic acid bacteria (LAB) fermentation. UHT (ultra-high temperature) sterilized milk was inoculated with Bulgarian yogurt and placed into a quartz cuvette (1 mm pathlength) and test-tubes. Yogurt absorbance spectra (830–2500 nm) were acquired every 15 min, and pH, in the respective test-tubes, was measured every 30 min, during 8 h of fermentation. Spectral data showed substantial baseline and slope changes with acidification. These variations corresponded to respective features of the microbiological growth curve showing water structural changes, protein denaturation, and coagulation of milk. Moving Window Principal Component Analysis (MWPCA) was applied in the spectral range of 954–1880 nm to detect absorbance bands where most variations in the loading curves were caused by LAB fermentation. Characteristic wavelength regions related to the observed physical and multiple chemical changes were identified. The results proved that NIRS is a valuable tool for real-time monitoring and better understanding of the yogurt fermentation process.