Development of antioxidant activity in milk whey during fermentation with lactic acid bacteria

Bioactivity and volatile compound evaluation in sheep milk processed by ohmic heating

Ohmic heating may improve bioactive compounds and processing, ensuring food safety of beverages, liquid and pasty food, or liquid with solid pieces. Due to those traits, this study conducted a comparison between ohmic heating technology and conventional heating (CH), with a focus on assessing the impact of both methods on functional compounds (such as angiotensin-converting enzyme inhibition, α-amylase and α-glucosidase inhibition, and antioxidant activity) in both fresh and thawed raw sheep milk, which had been frozen for up to 3 mo. Different ohmic heating conditions were applied and compared to CH (3.33-8.33 V/cm vs. CH [73°C/15 s]). A total of 18 peptides with some functional activities were identified by MALDI-TOF mass spectrometry analysis. Ohmic heating samples presented the highest activities related to health, followed by CH and raw milk samples; antioxidant activity range was from 0.11% to 0.71%, antihypertensive activity ranged from 0.20% to 0.72%, and antidiabetic activity ranged from 0.21% to 0.79%. Of 51 volatile compounds detected, some were degraded by freezing, storing, and heating the sheep milk. This study showed for the first time that ohmic heating processing improved sheep milk bioactive peptides and preserved volatile compounds.

Impact of ultrasonicated Lactobacillus delbrueckii subsp. bulgaricus, Streptococcus thermophilus and Lactiplantibacillus plantarum AF1 on the safety and bioactive properties of stirred yoghurt during storage

In this study, the effects of ultrasonicated Lactobacillus delbrueckii subsp. bulgaricus, Streptococcus thermophilus and Lactiplantibacillus plantarum AF1 (100 W, 30 kHz, 3 min) on the safety and bioactive properties of stirred yoghurt during storage (4 °C for 21 days) were investigated. The results showed that sonicated cultures were more effective in reducing pathogens than untreated ones. The highest antioxidant activity (DPPH and ABTS), α-glucosidase and α-amylase inhibition capacity were found in yoghurt containing sonicated probiotic + sonicated yoghurt starter cultures (P + Y + ). The highest amount of peptides (12.4 mg/g) was found in P + Y + yoghurts at the end of the storage time. There were not significant differences between the exopolysaccharide content of P + Y+ (17.30 mg/L) and P + Y- (17.20 mg/L) yoghurts, although it was significantly (P ≤ 0.05) higher than the other samples. The use of ultrasonicated cultures could enhance the safety of stirred yoghurt and improve its functional and bioactive properties.

Effect of Milk Origin and Seasonality of Yogurt Acid Whey on Antioxidant Activity before and after In Vitro Gastrointestinal Digestion

Yogurt acid whey (YAW) is a by-product of Greek strained yogurt production. The disposal of YAW constitutes an environmental problem, and given the increasing demand of Greek yogurt worldwide, its handling is a challenge. However, whey-derived peptides, resulting from microbial fermentation as well as those resulting from further hydrolysis during the digestion process, have been linked to enhanced biological activities. In this study, the antioxidant capacity of 33 samples of YAW obtained from Greek dairy companies of bovine, ovine or caprine origin was investigated using both cell-free and cell-based assays. The YAW samples, their in vitro digestion products (YAW-Ds) and a fraction of the digests (less than 3 kDa; YAW-D-P3) were assessed using four biochemical assays, namely ORAC, ABTS, FRAP and P-FRAP. Our data revealed a higher antioxidant capacity for digested samples compared with undigested samples, with all four methods. ORAC values after in vitro digestion were higher for the ovine samples compared to their bovine (YAW-D and YAW-D-P3) and caprine (YAW-D-P3) counterparts. Furthermore, the YAW-D-P3 fraction derived from samples collected in the summer months exhibited higher ORAC values when compared to the respective fraction from the winter months' samples. The cellular antioxidant activity of ovine YAW-D-P3 was improved in H2O2-treated HT29 cells compared to the control H2O2-treated cells. However, YAW-D-P3 could not trigger either the pathways involving the transcription factors NF-κB or NFE2L2 or the gene expression of SOD1, CAT and HMOX1 in LPS-challenged THP-1-derived macrophages. These results suggest that YAW, and particularly YAW from ovine origin, could be used as a natural source for its antioxidant potential in human and animal nutrition.

Bioactive Ingredients from Dairy-Based Lactic Acid Bacterial Fermentations for Functional Food Production and Their Health Effects

Lactic acid bacteria are traditionally applied in a variety of fermented food products, and they have the ability to produce a wide range of bioactive ingredients during fermentation, including vitamins, bacteriocins, bioactive peptides, and bioactive compounds. The bioactivity and health benefits associated with these ingredients have garnered interest in applications in the functional dairy market and have relevance both as components produced in situ and as functional additives. This review provides a brief description of the regulations regarding the functional food market in the European Union, as well as an overview of some of the functional dairy products currently available in the Irish and European markets. A better understanding of the production of these ingredients excreted by lactic acid bacteria can further drive the development and innovation of the continuously growing functional food market.

Digestion-resistant whey peptides promote antioxidant effect on Caco-2 cells

Enteric endothelial cells are the first structure to come in contact with digested food and may suffer oxidative damage by innumerous exogenous factors. Although peptides derived from whey digestion have presented antioxidant potential, little is known regarding antioxidant pathways activation in Caco-2 cell line model. Hence, we evaluated the ability to form whey peptides resistant to simulated gastrointestinal digestive processes, with potential antioxidant activity on gastrointestinal cells and associated with sequence structure and activity. Using the INFOGEST method of simulated static digestion, we achieved 35.2% proteolysis, with formation of peptides of low molecular mass (<600 Da) evaluated by FPLC. The digestion-resistant peptides showed a high proportion of hydrophobic and acidic amino acids, but with average surface hydrophobicity. We identified 24 peptide sequences, mainly originated from β-lactoglobulin, that exhibit various bioactivities. Structurally, the sequenced peptides predominantly contained the amino acids lysine and valine in the N-terminal region, and tyrosine in the C-terminal region, which are known to exhibit antioxidant properties. The antioxidant activity of the peptide digests was on average twice as potent as that of the protein isolates for the same concentration, as evaluated by ABTS, DPPH and ORAC. Evaluation of biological activity in Caco-2 intestinal cells, stimulated with hydrogen peroxide, showed that they attenuated the production of reactive oxygen species and prevented GSH reduction and SOD activity increase. Caco-2 cells were not responsive to nitric oxide secretion. This study suggests that whey peptides formed during gastric digestion exhibit biological antioxidant activity, without the need for previously hydrolysis with exogenous enzymes for supplement application. The study's primary contribution was demonstrating the antioxidant activity of whey peptides in maintaining the gastrointestinal epithelial cells, potentially preventing oxidative stress that affects the digestive system.

Safety aspects, probiotic potentials of yeast and lactobacillus isolated from fermented foods in North-Eastern India, and its anti-inflammatory activity

Lactobacillus and yeast obtained from fermented foods in North-East India were tested for safety and probiotic properties. All the lactobacilli and yeast tested negative for the catalase, indole, urease, phenylalanine, hemolysis, gelatin hydrolysis, and biogenic amine production tests, indicating that they are safe to use as probiotics in food supplements. Lactiplantibacillus plantarum KGL3A (accession no. MG722814) was capable of resisting the replicated gastric fluid (pH 2) till 2 h of exposure, whereas both KGL3A and Lacticaseibacillus rhamnosus K4E (accession no. KX950834.1) strains were able to resist pH 3 till 2 h of exposure with a reduction in overall viable cell count from 7.48 log CFU/mL to 1.09 log CFU/mL and 7.77 log CFU/mL to 0.83 log CFU/mL, respectively. In vitro gastric juice simulation conditions were tolerated by the yeast Saccharomyces cerevisiae WBS2A. The cell surface hydrophobicity (CSH) towards hydrocarbons (n-hexadecane) was seen highest in L. plantarum KGL3A (77.16± 0.84%) and Limosilactobacillus fermentum KGL4 accession no. MF951099 (72.60 ± 2.33%). The percentage auto-aggregation ranged from 8.70 to 25.53 after 2 h, which significantly increased to 10.50 to 26.94 during the fifth hour for cultures. Also, a higher percentage of co-aggregation was found for the culture L. rhamnosus K4E with S. typhi (34.18 ± 0.03%), E. coli (32.97 ± 0.02 %) and S. aureus (26.33 ± 0.06 %) and for the yeast S. cerevisiae WBS2A, a higher percentage of co-aggregation was found with Listeria monocytogenes (25.77 ± 0.22%). The antioxidant activity and proteolytic activity were found to be higher for Lactobacillus helveticus K14 and L. rhamnosus K4E. The proportion of decreased cholesterol was noticeably higher in KGL4 (29.65 ± 4.30%). β glucosidase activity was significantly higher in the L. fermentum KGL4 strain (0.359 ± 0.002), and α galactosidase activity was significantly higher in the L. rhamnosus K4E strain (0.415 ± 0.016). MTT assays suggested that KGL4 and WBS2A at a lower dose did not exhibit cytotoxicity.

Promising role of Lawsonia inermis L. leaves extract and its nano-formulation as double treatment against aflatoxin toxicity in ulcerated-rats: Application in milk beverage

Aflatoxins are an unavoidable contaminant of foods. The current work aimed to study the ameliorating effect of Lawsonia inermis L. extract and its nano-formulation versus aflatoxin ingestion in ulcerative rats. Lawsonia inermis L. bioactivity was evaluated by both antioxidant & antimicrobial assays. The nanoparticles characterization measurements were evaluated. Different parameters in the fortified milk beverage were assessed. Seventy two Sprague-Dawley male rats were randomized into 12 groups (6 rats/group) where peptic ulcer was induced with a single aspirin dose (500 mg/kg BW) orally. The nutritional and biochemical parameters were evaluated. The results showed that antioxidant activity and total phenolic content increased with increasing nano-formulation ratio. A remarkable improvements in all the treated groups, either for ulcer alone or for aflatoxin exposed ulcerative groups in normal and nano-formulation. Conclusively, Lawsonia inermis L. & its nano-formulation could act as dual therapy for ulcer treatment and the hazardous effects of aflatoxin exposure.

Bacteriocin and Antioxidant Production, a Beneficial Properties of Lactic Acid Bacteria Isolated from Fermented Vegetables of Northwest Bulgaria

Lactiplantibacillus plantarum ST01BG, ST07BG, ST10BG, and ST15BG; Latilactobacillus curvatus ST02BG; Lacticaseibacillus paracasei ST04BG; Pediococcus pentosaceus ST05BG; Leuconostoc mesenteroides ST06BG; and Enterococcus faecium ST11BG were isolated from home-made fermented vegetables from Northwest Bulgaria and identified by biochemical, physiological, and biomolecular analyses, including partial 16S rRNA sequencing. The strains were designated as bacteriocin producers and the expressed antimicrobials partially characterized with a focus on their proteinaceous nature, stability to different pH and temperatures. The bacteriocins were effective in inhibiting different strains of Listeria spp., Enterococcus spp. (including vancomycin resistant enterococci) and Staphylococcus spp. These strains can be considered safe, based on the evaluation of hemolytic activity, production of biogenic amines, mucin degradation, antibiotic susceptibility/resistance, and gelatinase enzyme production. Moreover, the strains can be considered potentially beneficial based on their stability and survival under simulated gastrointestinal tract conditions (stomach and duodenum), the production of diacetyl, and specific levels of hydrophobicity. Special attention was given to antioxidant properties (DPPH radical, hydroxyl radical, superoxide anion radical scavenging activity, Fe+2 ion chelating activity, and anti-lipid peroxidation) of the strains. Antioxidant properties were found to be strain specific. The beneficial attributes (antimicrobial and antioxidant) of these cultures to fermented food products may enable the reduction of chemical additives in line with consumers' demand for more natural and chemical-free food commodities.

Beneficial, safety, and antioxidant properties of lactic acid bacteria: A next step in their evaluation as potential probiotics

The role of lactic acid bacteria (LAB) as probiotics as health promoting factors for human or veterinary practice has gained increasing interest during the last three decades. This is reflected in screening approaches of LAB strains in line with minimal requirements for a "probiotic" with regard to safety and functionality. The latter might also include natural antioxidant properties, thereby constituting an additional benefit in substituting synthetic antioxidants. The in vitro antioxidant assays conducted in this study included the scavenging of the 2,2-diphenyl-1-picrylhydrazil (DPPH) free radical, metal (Fe⁺²) ion chelation, determining the scavenging properties of the hydroxyl and superoxide radicals, and anti-lipid peroxidation. Analysis of DPPH free radical scavenging property for the microorganisms included in current study, showed Streptococcus salivarius ST59HK to exhibit the highest activity at a level of 85.24%. The greatest Fe⁺² chelation activity with 98.2% was recorded for Str. salivarius ST62HK while the lowest was recorded for Str. salivarius ST48HK at 71.5%. The greatest and minimal hydroxyl radical scavenging levels were detected for Str. salivarius ST59HK (98.6%) and Lactiplantibacillus plantarum ST63HK (35.60%), respectively. Superoxide anion radical scavenging activity was highly exhibited by Str. salivarius ST61HK (54.62%) and the least exhibited by Enterococcus faecium ST651ea (18.7%). Lastly, the strains Lactobacillus gasseri ST16HK and E. faecium ST7319ea showed the highest and lowest anti-lipid peroxidation levels with 69.43% and 26.15%, respectively. Anti-oxidative properties appear to be strain specific and thus some of these strains could be potentially applied as natural antioxidants in fermented food products.

Effects of a Lactobacillus fermentation product on the fecal characteristics, fecal microbial populations, immune function, and stress markers of adult dogs

The objective of this study was to measure the effects of a Lactobacillus fermentation product (LBFP) on fecal characteristics and microbiota, blood biomarkers, immune function, and serum oxidative stress markers of adult dogs. Thirty adult beagle dogs [23 M, 7 F; mean age = 8.47 ± 2.65 yr old; mean BW = 15.43 ± 4.17 kg] were used in a completely randomized design study. All dogs were fed a basal diet to maintain BW for 5 wk, followed by baseline blood and fecal sample collections. Dogs remained on the same diet, but then were randomly assigned to a placebo (dextrose) or LBFP supplement (Limosilactobacillus fermentum and Lactobacillus delbrueckii). Both treatments were dosed at 4 mg/kg BW via gelatin capsule for 5 wk (n = 15/treatment). Fecal and blood samples were collected at that time. Change from baseline data were analyzed using the Mixed Models procedure of SAS 9.4, with P < 0.05 being significant and P < 0.10 being trends. Most circulating metabolites and immunoglobulins (Ig) were unaltered by treatment, but LBFP-supplemented dogs had lower changes in serum corticosteroid isoenzyme of alkaline phosphatase (P < 0.05), alanine aminotransferase (P < 0.10), and IgM (P < 0.10) than controls. The change in fecal scores tended to be lower (P = 0.068) in LBFP-supplemented dogs than controls, signifying firmer feces in LBFP-supplemented dogs. Regarding the fecal microbiota, alpha diversity indicators tended to be higher (P = 0.087) in LBFP-supplemented dogs than controls. One fecal bacterial phylum (Actinobacteriota) was altered by treatments, with its relative abundance tending to have a greater (P < 0.10) increase in controls than LBFP-supplemented dogs. Fifteen bacterial genera were altered (P < 0.05 or P < 0.10) by treatments, including relative abundances of fecal Peptoclostridium, Sarcina, and Faecalitalea that had a greater (P < 0.05) increase in controls than LBFP-supplemented dogs. In contrast, relative abundances of fecal Faecalibaculum, Bifidobacterium, and uncultured Butyricicoccaceae had a greater (P ≤ 0.05) increase in LBFP-supplemented dogs than controls. After week 5, dogs underwent transport stress (45-min vehicle ride) to assess oxidative stress markers. The change in serum superoxide dismutase after transport had a greater (P < 0.0001) increase in LBFP-supplemented dogs than controls. Our data suggest that LBFP may provide benefits to dogs by stabilizing stool quality, beneficially shifting fecal microbiota, and protecting against oxidative damage when subjected to stress.

Separation and Purification of Antioxidant Peptide from Fermented Whey Protein by Lactobacillus rhamnosus B2-1

In this study, a antioxidant activity peptide fraction was separated and purified from metabolites of whey protein fermented by Lactobacillus rhamnosus B2-1. The fermentation sample was separated by macroporous resin D101 and Sephadex G-15. The collected fractions were tested for antioxidant and antitumor activities. In order to test the antioxidant activity of fractions, Hydroxyl (·OH), 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid (ABTS), and Oxygen Radical Absorbance Capacity (ORAC) were used. The final purified peptide B11 showed highest ABTS and ·OH radical scavenging rate by 84.36±1.89% and 62.43±2.64%, respectively, and had an ORAC activity of 1,726.44± 2.76 μM Trolox equivalent/g. Further, the inhibitory effect of B11 on the proliferation of LoVo human colon cancer cells, KB and Cal-27 human oral cancer cells were enhanced with increasing concentrations of B11. B11 contains 51.421% amino acids, with Glu and Asp being the major constituents. In this study, we obtained peptide fraction B11 with antioxidant activity, which is promising for development.

Utilization of durian seed for Monascus fermentation and its application as a functional ingredient in yogurt

As a widely consumed fermented milk product, yogurt undergoes constant development to increase its functional properties. Monascus purpureus-fermented durian seed, which has been proven to possess antioxidative properties, has the potential to improve yogurt properties. This study aimed to analyze the use of Monascus-fermented durian seed (MFDS) as a functional ingredient in yogurt and its effect on physicochemical properties, lactic acid bacteria (LAB) count, antioxidative properties, and consumer acceptability of set-type yogurt during refrigeration. Changes in physicochemical properties, including color, pH, titratable acidity, syneresis, LAB count, total phenolic content (TPC), and antioxidant activity were evaluated at 7-day intervals during 14 days of refrigerated storage (4 °C). Sensory evaluations were carried out for freshly made samples after 7 days of storage. The results showed that the addition of MFDS to yogurt gave significant effects on some of the parameters measured. Yogurt with added MFDS powder produced a more red color (L = 88.55 ± 1.28, a* = 2.63 ± 0.17, b* = 11.45 ± 1.15, c = 11.75 ± 1.15, H = 77.00 ± 0.64), reached the highest TPC (2.21 ± 0.46 mg/GAE g), antioxidant activity (0.0125 ± 0.0032 mg GAE/g), and syneresis (5.24 ± 0.51%) throughout 14 days of storage. The addition of MFDS only gave a slight difference to pH and titratable acidity, while no significant difference was made for LAB count. For sensory evaluation, the addition of MFDS, particularly the ethanol extract, to yogurt was well-liked by panelists. Citrinin content in MFDS yogurt can be decreased under the limits set. Overall, the addition of MFDS has a high potential of improving yogurt properties, particularly its antioxidative properties.

Isolation, identification, and characterization of corn-derived antioxidant peptides from corn fermented milk by Limosilactobacillus fermentum

Dairy-derived peptides and corn-derived peptides have been identified as essential ingredients for health promotion in the food industry. The hydrolysis based on lactic acid bacteria (LAB) protease system is one of the most popular methods to prepare bioactive peptides. The objectives of this paper are to develop antioxidant fermented milk and to obtain natural antioxidant peptides. In our study, LAB with antioxidant capacity were screened in vitro, and the corn fermented milk with antioxidant capacity was achieved by the traditional fermentation method. Fermented milk was purified by ultrafiltration and molecular sieve, and identified by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Our findings demonstrate that Limosilactobacillus fermentum L15 had a scavenging capacity of more than 80% of DPPH radicals, Trolox equivalent antioxidant capacity (TEAC) of 0.348 ± 0.005 mmol/L. Meanwhile, the peptide content of corn fermented milk prepared with L. fermentum L15 was 0.914 ± 0.009 mg/mL and TAEC of 0.781 ± 0.020 mmol/L. Particularly important, IGGIGTVPVGR and LTTVTPGSR isolated and extracted from fermented milk were found to have antioxidant capacity for the first time. The synthetic peptides IGGIGTVPVGR and LTTVTPGSR demonstrated a scavenging capacity of 70.07 ± 2.71% and 70.07 ± 2.77% for DPPH radicals and an antioxidant capacity of 0.62 ± 0.01 mmol/L and 0.64 ± 0.02 mmol/L Trolox equivalent, respectively. This research provides ideas and basis for the development and utilization of functional dairy products.

Value-Added Utilization of Citrus Peels in Improving Functional Properties and Probiotic Viability of Acidophilus-bifidus-thermophilus (ABT)-Type Synbiotic Yoghurt during Cold Storage

Citrus peel, a fruit-processing waste, is a substantial source of naturally occurring health-promoting compounds, including polyphenols, and has great potential as a dietary supplement for enhancing the functional properties of food. The present work aimed to investigate the effects of sour orange (SO), sweet orange (SWO), and lemon (LO) peels on the typical physiochemical, antioxidant, antibacterial, and probiotic properties of synbiotic yoghurt fermented by acidophilus-bifidus-thermophilus (ABT)-type cultures during cold storage (0−28 days). High-performance liquid chromatography-diode array detection (HPLC-DAD) analysis showed that the total phenolic content in the SO peel were more than 2-fold higher than that in the SWO and LO peel. The predominant phenolic compounds were myricetin (2.10 mg/g dry weight) and o-coumaric acid (1.13 mg/g) in SO peel, benzoic acid (0.81 mg/g) and naringin (0.72 mg/g) in SWO peel, and benzoic acid (0.76 mg/g) and quercetin (0.36 mg/g) in LO peel. Only 0.5% (w/w) of citrus peel addition did not reduce the overall acceptance of ABT synbiotic yoghurt but led to increased acidity and decreased moisture during cold storage (14 and 28 days). Additionally, compared to control samples without citrus peel addition, supplementation with citrus peels improved the antioxidant property of the ABT synbiotic yoghurt. ABT milks with SO and SWO peel addition had significantly stronger DPPH radical scavenging activities than that with LO peel addition (p < 0.05). Antibacterial analysis of ABT synbiotic yoghurt with citrus peel addition showed that the diameters of inhibition zones against S. aureus, B. subtilis, and E. coli increased by 0.6−1.9 mm relative to the control groups, suggesting the enhancement of antibacterial activities by citrus peels. The viabilities of probiotic starter cultures (L. acidophilus, S. thermophilus, and Bifidobacterial sp.) were also enhanced by the incorporation of citrus peels in synbiotic yoghurt during cold storage. Hence, our results suggest that citrus peels, especially SO and SWO peels, could be recommended as a promising multifunctional additive for the development of probiotic and synbiotic yoghurt with enhanced antioxidant and antibacterial properties, as well as probiotic viability.

Antioxidative properties analysis of gastrointestinal lactic acid bacteria in Hainan black goat and its effect on the aerobic stability of total mixed ration

In this study, lactic acid bacteria strains (HCS-01, HCS-05, HCS-07, HCW-08, and HCW-09) derived from the gastrointestinal tract of Hainan black goat were evaluated for their antioxidant capacity in vitro, and the lactic acid bacteria with strong antioxidant capacity were screened for application to improve the aerobic stability of total mixed ration (TMR). The results showed that all the tested lactic acid bacteria had a certain tolerance to hydrogen peroxide. By comprehensively comparing the scavenging abilities of fermentation supernatants, whole cell bacterial suspensions and cell contents of five lactic acid bacteria strains to 2,2-diphenyl-1-picrylhydrazine (DPPH), hydroxyl radicals and superoxide anions, and their antioxidant enzyme activity, it was found that Lactobacillus fermentum HCS-05 and Lactobacillus plantarum HCW-08 have the strongest comprehensive antioxidant capacity, and their scavenging capacity for various free radicals has reached more than 60%. Using strains HCS-05, HCW-08 and laboratory-preserved Lactobacillus plantarum HDX1 fermented TMR, the fermentation quality and aerobic stability of the feed after 60 days of fermentation were significantly higher than those of the blank treatment group. The effect of mixed strains HCS-05 and HCS-08 for TMR fermentation was the best (P &lt; 0.05). At the same time, the fermentation effect of Lactobacillus plantarum HDX1 on TMR was significantly lower than that of the selected lactic acid bacteria from the gastrointestinal tract of Hainan black goats (P &lt; 0.05). The results show that the test strain can significantly improve the aerobic stability of the fermented feeds.

Antioxidant peptides derived from hydrolyzed milk proteins by Lactobacillus strains: A BIOPEP-UWM database-based analysis

Milk-derived peptides have been identified as the essential ingredients in the food industry for the health-promoting properties. Some bioactive peptides in the milk product can be released by the specific protease system of lactic acid bacteria (LAB) during the fermentation processing. In this research, the bioactive peptides released from the casein and whey protein are investigated by the hydrolyzing ability of the Lactobacillus brevis CGMCC15954, Lactobacillus reuteri WQ-Y1 and Lactobacillus plantarum A3. Results found that the hydrolysates of casein/whey protein generated by L. reuteri WQ-Y1 have the potential antioxidant activity. Furthermore, milk-derived peptides identified by the liquid chromatography-mass spectrometry (LC-MS/MS) with the BIOPEP-UWM database showed the YLGYLEQLLR (α_S1-casein), VKEAMAPK (β-casein), YIPIQYVLSR (κ-casein) fragment had the promising antioxidant activity, especially VKEAMAPK, which exhibited IC₅₀ of 0.63 and 0.86 mg/mL in DPPH and ABTS free radical scavenging activity. The finding of this study sheds some light of obtaining milk-derived peptides by using the Lactobacillus strains and proves the potential bioactive function of the LAB fermented milk products.

Effect of Purple Corn Anthocyanin on Antioxidant Activity, Volatile Compound and Sensory Property in Milk During Storage and Light Prevention

The aim of this study was to observe the effect of purple corn anthocyanin on the light-induced antioxidant activity, free radicals, volatile compounds, color parameters, and sensory properties of milk during storage. There were four groups: (1) negative control, no addition of anthocyanins + exposure to fluorescent light (NC); (2) positive control 1, no addition of anthocyanins + protected from fluorescent light (PC1); (3) positive control 2, the addition of 0.3% (w/v) anthocyanins + exposure to fluorescent light (PC2); and (4) the addition of 0.3% anthocyanins + protected from fluorescent light (AC). The results indicated that the concentration of antioxidant activity parameters in the NC group decreased during the entire storage period, whereas antioxidant activity parameters were unchanged except for the glutathione peroxidase (GSH-Px) in the AC group. Moreover, the NC group showed lower levels of 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging activity and higher levels of superoxide anion and hydrogen peroxide than the other groups after 1 d of storage period. The extent of malondialdehyde accumulation and lipid peroxidation in the control groups were greater than that of the AC group. Twenty-two volatile compounds were determined in milk, which consisted of eight alcohols, three ketones, five aldehydes, two esters, and four hydrocarbons by headspace gas chromatography mass spectrometer analysis. Specifically, individual aldehydes, esters and hydrocarbons in the AC group remained at relatively stable values during storage relative to the other three groups. Stronger positive correlations were detected between several antioxidant activities (superoxide dismutase, GSH-Px) and DPPH scavenging activity as well as total ketones in milk. Adding of anthocyanin did not impact on the color values of L^*, a^* and b^* in light-protected milk during the entire storage period. Some sensory evaluation parameters (flat, garlic/onion/weedy, oxidized-light, oxidized-metal, rancid) in AC group were significantly higher than that of the control group at the end of the period. In conclusion, the current study revealed that the addition of purple corn anthocyanin pigment to light-protected milk had the potential to prevent lipid oxidation, enhance antioxidant activity, maintain volatile compounds and increase the sensory scores.

Antioxidant and Antimicrobial Peptides Derived from Food Proteins

Recently, the demand for food proteins in the market has increased due to a rise in degenerative illnesses that are associated with the excessive production of free radicals and the unwanted side effects of various drugs, for which researchers have suggested diets rich in bioactive compounds. Some of the functional compounds present in foods are antioxidant and antimicrobial peptides, which are used to produce foods that promote health and to reduce the consumption of antibiotics. These peptides have been obtained from various sources of proteins, such as foods and agri-food by-products, via enzymatic hydrolysis and microbial fermentation. Peptides with antioxidant properties exert effective metal ion (Fe2+/Cu2+) chelating activity and lipid peroxidation inhibition, which may lead to notably beneficial effects in promoting human health and food processing. Antimicrobial peptides are small oligo-peptides generally containing from 10 to 100 amino acids, with a net positive charge and an amphipathic structure; they are the most important components of the antibacterial defense of organisms at almost all levels of life-bacteria, fungi, plants, amphibians, insects, birds and mammals-and have been suggested as natural compounds that neutralize the toxicity of reactive oxygen species generated by antibiotics and the stress generated by various exogenous sources. This review discusses what antioxidant and antimicrobial peptides are, their source, production, some bioinformatics tools used for their obtainment, emerging technologies, and health benefits.

Identification and characterization of metal-chelating bioenhancer peptide derived from fermented Citrullus lanatus seed milk

In the present investigation, a metal-chelating bioactive peptide was derived from Citrullus lanatus seed milk fermented with Lactococcus lactis. The cationic fermented milk peptide (FMP) thus obtained was purified using the HiTrap-chelating column followed by rpHPLC. The FMP possessed the ability to chelate multiple divalent cations like Cu²⁺ , Ca²⁺ , and Fe²⁺ with 86.81%, 61.04%, and 24.32% of chelation respectively and further it exhibited 78.03% of DPPH free radical scavenging activity. Interaction of FMP with metal ions was assessed by change in the absorption spectra and was analyzed by ultraviolet-visible and fluorescence spectroscopy. The FMP-metal complexes were found stable at simulated gastric conditions. In vitro analysis using intestinal Caco-2 cell lines revealed that there was an increase in metal bioavailability in the presence of the FMP and was least influenced by the addition of a dietary inhibitor, phytic acid. By LC-MS analysis the molecular mass of FMP was found to be 11.6 kD and it contains oxygen-rich and nitrogen-rich amino acids that favor the metal chelation. In our study, we have found that the fermented C. lanatus seed milk can serve as a potential functional food with bioenhancer peptides that increase metal bioavailability and enhance human health. PRACTICAL APPLICATIONS: Chelated metals are preferred over non-chelated ones by most nutritionists for their better absorption rate. Chelation protects the minerals from the digestive process and increases their bioavailability. Fermentation with lactic acid bacteria produces bioactive peptides with metal-chelating and antioxidant ability which provides additional health benefits beyond supplying basic nutrients. Lactococcus lactis fermented milk acts as a probiotic product with bioenhancer peptide that increases mineral bioavailability. Consumption of metals in chelated form can reduce excess intake of metal. Fermented watermelon seed milk can be a promising probiotic drink rich in bioenhancer peptides and can enhance the bioavailability of divalent cations of a high therapeutic index.

Antioxidant Activity of Milk and Dairy Products

The aim of the study was to present a review of literature data on the antioxidant potential of raw milk and dairy products (milk, fermented products, and cheese) and the possibility to modify its level at the milk production and processing stage. Based on the available reports, it can be concluded that the consumption of products that are a rich source of bioactive components improves the antioxidant status of the organism and reduces the risk of development of many civilization diseases. Milk and dairy products are undoubtedly rich sources of antioxidant compounds. Various methods, in particular, ABTS, FRAP, and DPPH assays, are used for the measurement of the overall antioxidant activity of milk and dairy products. Research indicates differences in the total antioxidant capacity of milk between animal species, which result from the differences in the chemical compositions of their milk. The content of antioxidant components in milk and the antioxidant potential can be modified through animal nutrition (e.g., supplementation of animal diets with various natural additives (herbal mixtures, waste from fruit and vegetable processing)). The antioxidant potential of dairy products is associated with the quality of the raw material as well as the bacterial cultures and natural plant additives used. Antioxidant peptides released during milk fermentation increase the antioxidant capacity of dairy products, and the use of probiotic strains contributes its enhancement. Investigations have shown that the antioxidant activity of dairy products can be enhanced by the addition of plant raw materials or their extracts in the production process. Natural plant additives should therefore be widely used in animal nutrition or as functional additives to dairy products.

Dairy Lactic Acid Bacteria and Their Potential Function in Dietetics: The Food-Gut-Health Axis

Fermented dairy products are the good source of different species of live lactic acid bacteria (LAB), which are beneficial microbes well characterized for their health-promoting potential. Traditionally, dietary intake of fermented dairy foods has been related to different health-promoting benefits including antimicrobial activity and modulation of the immune system, among others. In recent years, emerging evidence suggests a contribution of dairy LAB in the prophylaxis and therapy of non-communicable diseases. Live bacterial cells or their metabolites can directly impact physiological responses and/or act as signalling molecules mediating more complex communications. This review provides up-to-date knowledge on the interactions between LAB isolated from dairy products (dairy LAB) and human health by discussing the concept of the food–gut-health axis. In particular, some bioactivities and probiotic potentials of dairy LAB have been provided on their involvement in the gut–brain axis and non-communicable diseases mainly focusing on their potential in the treatment of obesity, cardiovascular diseases, diabetes mellitus, inflammatory bowel diseases, and cancer.

Flavonoid-Rich Extract of Paeonia lactiflora Petals Alleviate d-Galactose-Induced Oxidative Stress and Restore Gut Microbiota in ICR Mice

This study was aimed to investigate the antioxidant effect of Paeonia lactiflora Pall. petal flavonoids extract (PPF) on d-galactose (d-gal)-induced ICR mice. In this study, sixty male ICR mice were randomly divided into six groups during an 8 weeks experimental period, including normal control (NC) group, d-gal group, epigallocatechin gallate (EGCG) group, low, medium, and high dose PPF groups (10, 20 and 40 mg/kg/day). The results showed that intragastric administration with PPF significantly reverses the atrophy of the visceral organs of oxidative damage mice in a dose-dependent relationship. PPF indicated the antioxidant capacity to decrease the malondialdehyde (MDA) level and improve the activity of superoxide dismutase (SOD), catalase (CAT) as well as glutathione peroxidase (GSH-Px). In addition, PPF treatment reversed gut microbiota dysbiosis by increasing the relative abundance of Lactobacillaceae. Spearman correlation analysis showed that the body's oxidative stress markers were directly related to changes in gut microbiota. These findings reveal firstly that PPF could alleviate d-Gal-induced oxidative stress and modulate gut microbiota balance.

Biomarkers and Utility of the Antioxidant Potential of Probiotic Lactobacilli and Bifidobacteria as Representatives of the Human Gut Microbiota

Lactobacilli and bifidobacteria are an important part of human gut microbiota. Among numerous benefits, their antioxidant properties are attracting more and more attention. Multiple in vivo and in vitro studies have demonstrated that lactobacilli and bifidobacteria, along with their cellular components, possess excellent antioxidant capacity, which provides a certain degree of protection to the human body against diseases associated with oxidative stress. Recently, lactobacilli and bifidobacteria have begun to be considered as a new source of natural antioxidants. This review summarizes the current state of research on various antioxidant properties of lactobacilli and bifidobacteria. Special emphasis is given to the mechanisms of antioxidant activity of these bacteria in the human gut microbiota, which involve bacterial cell components and metabolites. This review is also dedicated to the genes involved in the antioxidant properties of lactobacilli and bifidobacteria strains as indicators of their antioxidant potential in human gut microbiota. Identification of the antioxidant biomarkers of the gut microbiota is of great importance both for creating diagnostic systems for assessing oxidative stress and for choosing strategies aimed at restoring the normal functioning of the microbiota and, through it, restoring human health. In this review, the practical application of probiotic strains with proven antioxidant properties to prevent oxidative stress is also considered.

Donkey Milk Fermentation by Lactococcus lactis subsp. cremoris and Lactobacillus rhamnosus Affects the Antiviral and Antibacterial Milk Properties

BACKGROUND

Milk is considered an important source of bioactive peptides, which can be produced by endogenous or starter bacteria, such as lactic acid bacteria, that are considered effective and safe producers of food-grade bioactive peptides. Among the various types of milk, donkey milk has been gaining more and more attention for its nutraceutical properties.

METHODS

Lactobacillus rhamnosus 17D10 and Lactococcus lactis subsp. cremoris 40FEL3 were selected for their ability to produce peptides from donkey milk. The endogenous peptides and those obtained after bacterial fermentation were assayed for their antioxidant, antibacterial, and antiviral activities. The peptide mixtures were characterized by means of LC-MS/MS and then analyzed in silico using the Milk Bioactive Peptide DataBase.

RESULTS

The peptides produced by the two selected bacteria enhanced the antioxidant activity and reduced E. coli growth. Only the peptides produced by L. rhamnosus 17D10 were able to reduce S. aureus growth. All the peptide mixtures were able to inhibit the replication of HSV-1 by more than 50%. Seventeen peptides were found to have 60% sequence similarity with already known bioactive peptides.

CONCLUSIONS

A lactic acid bacterium fermentation process is able to enhance the value of donkey milk through bioactivities that are important for human health.

Lactobacillus plantarum Exhibits Antioxidant and Cytoprotective Activities in Porcine Intestinal Epithelial Cells Exposed to Hydrogen Peroxide

Probiotics are widely used for protection against stress-induced intestinal dysfunction. Oxidative stress plays a critical role in gastrointestinal disorders. It is established that probiotics alleviate oxidative stress; however, the mechanism of action has not been elucidated. We developed an in vitro intestinal porcine epithelial cells (IPEC-J2) model of oxidative stress to explore the antioxidant effect and potential mode of action of Lactobacillus plantarum ZLP001. The IPEC-J2 cells were preincubated with and without L. plantarum ZLP001 for 3 h and then exposed to hydrogen peroxide (H₂O₂) for 4 h. Pretreatment with L. plantarum ZLP001 protected IPEC-J2 cells against H₂O₂-induced oxidative damage as indicated by cell viability assays and significantly alleviated apoptosis elicited by H₂O₂. L. plantarum ZLP001 pretreatment decreased reactive oxygen species production and the cellular malondialdehyde concentration and increased the mitochondrial membrane potential compared with H₂O₂ treatment alone, suggesting that L. plantarum ZLP001 promotes the maintenance of redox homeostasis in the cells. Furthermore, L. plantarum ZLP001 regulated the expression and generation of some antioxidant enzymes, thereby activating the antioxidant defense system. Treatment with L. plantarum ZLP001 led to nuclear erythroid 2-related factor 2 (Nrf2) enrichment in the nucleus compared with H₂O₂ treatment alone. Knockdown of Nrf2 significantly weakened the alleviating effect of L. plantarum ZLP001 on antioxidant stress in IPEC-J2 cells, suggesting that Nrf2 is involved in the antioxidative effect of L. plantarum ZLP001. Collectively, these results indicate that L. plantarum ZLP001 is a promising probiotic bacterium that can potentially alleviate oxidative stress.

Antioxidant and Antimelanogenic Activities of Kimchi-Derived Limosilactobacillus fermentum JNU532 in B16F10 Melanoma Cells

Melanin is a natural skin pigment produced by specialized cells called melanocytes via a multistage biochemical pathway known as melanogenesis, involving the oxidation and polymerization of tyrosine. Melanogenesis is initiated upon exposure to ultraviolet (UV) radiation, causing the skin to darken, which protects skin cells from UVB radiation damage. However, the abnormal accumulation of melanin may lead to the development of certain skin diseases, including skin cancer. In this study, the antioxidant and antimelanogenic activities of the cell-free supernatant (CFS) of twenty strains were evaluated. Based on the results of 60% 2,2-diphenyl-1-picrylhydrazyl scavenging activity, 21% 2,2'-azino-bis (3-ethylbenzthiazoline-6-sulfonic acid) scavenging capacity, and a 50% ascorbic acid equivalent ferric reducing antioxidant power value, Limosilactobacillus fermentum JNU532 was selected as the strain with the highest antioxidant potential. No cytotoxicity was observed in cells treated with the CFS of L. fermentum JNU532. Tyrosinase activity was reduced by 16.7% in CFStreated B16F10 cells (but not in the cell-free system), with >23.2% reduction in melanin content upon treatment with the L. fermentum JNU532-derived CFS. The inhibitory effect of the L. fermentum JNU532-derived CFS on B16F10 cell melanogenesis pathways was investigated using quantitative reverse transcription polymerase chain reaction and western blotting. The inhibitory effects of the L. fermentum JNU532-derived CFS were mediated by inhibiting the transcription of TYR, TRP-1, TRP-2, and MITF and the protein expression of TYR, TRP-1, TRP-2, and MITF. Therefore, L. fermentum JNU532 may be considered a potentially useful, natural depigmentation agent.

In Vitro Antidiabetic, Antioxidant Activity, and Probiotic Activities of Lactiplantibacillus plantarum and Lacticaseibacillus paracasei Strains

Diabetes, a chronic metabolic disorder, is characterized by persistent hyperglycemia. This study aimed to evaluate the hypoglycemic and antioxidant activities of lactic acid bacteria strains isolated from humans and food products and investigate the probiotic properties of the selected four strains. The hypoglycemic activity of the isolated strains was examined by evaluating the α-glucosidase and α-amylase inhibitory activities. The antioxidant activity was measured using the DPPH, ABTS, and FRAP assays. Four strains (Lactiplantibacillus plantarum MG4229, MG4296, MG5025, and Lacticaseibacillus paracasei MG5012) exhibited potent α-glucosidase inhibitory (>75%) and α-amylase inhibitory (>85%) activities, which were comparable to those of acarbose (>50%; 1000 μg/mL). Similarly, the radical scavenging and antioxidant activities of the four strains were comparable to those of ascorbic acid (50 μg/mL). Additionally, the probiotic properties of the four selected strains were examined based on acid and bile salt tolerance, auto-aggregation ability, and antibiotic resistance. The four strains were resistant to pH 2 (>50% of survivability) and 0.5% bile salt (>80% of survivability). Therefore, we suggest that the selected strains with hypoglycemic, antioxidant, probiotic properties can potentially prevent diabetes.

Technological characterization of indigenous lactic acid bacteria from Moroccan camel milk for their potential use as starter or adjunct culture

This study aimed to isolate lactic acid bacteria (LABs) of technological interest from Moroccan camel milk and select starter or adjunct culture for dairy product manufacturing. The phenotypic and biochemical identification of 47 isolates revealed the existence of ten Lactococcus lactis, eleven Lactobacillus plantarum, three Lactobacillus brevis, two Lactobacillus paracasei, eleven Enterococcus spp., seven Lactococcus spp. and two Lactobacillus spp. Our strains showed a fast acidifying ability (ΔpH ranged between 0.69 ± 0.01 and 1.22 ± 0.05 after 6 h), high proteolytic and autolytic activities (1.93 ± 0.02 to 9.9 ± 0.022 mM glycine and 15.21 ± 2.21% to 83.24 ± 1% respectively), and an important lipolytic and free radical scavenging capacity. Furthermore, they were able to use citrate, to produce exopolysaccharide, and they exhibited antibacterial activity against Gram-negative and Gram-positive pathogenic bacteria and had no hemolytic activity. This study has shown that Moroccan camel milk represents a rich biotope of interesting LABs for dairy products industry.

Enhanced antioxidant activity of Chenopodium formosanum Koidz. by lactic acid bacteria: Optimization of fermentation conditions

In this study, different probiotics commonly used to produce fermented dairy products were inoculated independently for Chenopodium formosanum Koidz. fermentation. The strain with the highest level of antioxidant activity was selected and the fermentation process was further optimized via response surface methodology (RSM). Lactobacillus plantarum BCRC 11697 was chosen because, compared to other lactic acid bacteria, it exhibits increased free radical scavenging ability and can produce more phenolic compounds, DPPH (from 72.6% to 93.2%), and ABTS (from 64.2% to 76.9%). Using RSM, we further optimize the fermentation protocol of BCRC 11697 by adjusting the initial fermentation pH, agitation speed, and temperature to reach the highest level of antioxidant activity (73.5% of DPPH and 93.8% of ABTS). The optimal protocol (pH 5.55, 104 rpm, and 24.4°C) resulted in a significant increase in the amount of phenolic compounds as well as the DPPH and ABTS free radical scavenging ability of BCRC 11697 products. The IC50 of the DPPH and ABTS free radical scavenging ability were 0.33 and 2.35 mg/mL, respectively, and both protease and tannase activity increased after RSM. An increase in lower molecular weight (<24 kDa) protein hydrolysates was also observed. Results indicated that djulis fermented by L. plantarum can be a powerful source of natural antioxidants for preventing free radical-initiated diseases.

An Integrated Approach for the Valorization of Cheese Whey

Taking into account the large amount of whey that is produced during the cheese production process and the constant demand by society for more sustainable processes, in accordance with Sustainable Development Goals (SDGs) and the circular economy concept, it is necessary to adapt two-unit operations into a single process, allowing us to not only valorize a part of the whey but the whole process, which is known as bioprocess integration. In this sense, the adaptation of different processes, for example, physicochemical (micro, ultra and nanofiltration) and fermentation, that are commonly used to obtain proteins, lactose and other compounds with different activities (antioxidant, antifungal, etc.) could be integrated to achieve a complete recovery of the cheese whey. Likewise, keeping in mind that one of the main drawbacks of cheese whey is the great microbial load, some innovative processing technologies, such as high hydrostatic pressures, electrotechnologies and ultrasound, can allow both the development of new foods from whey as well as the improvement of the nutritional and organoleptic properties of the final products prepared with cheese, and thus reducing the microbial load and obtaining a safe product could be incorporated in the cheese whey valorization process.

Functional characterization and immunomodulatory properties of Lactobacillus helveticus strains isolated from Italian hard cheeses

Lactobacillus helveticus carries many properties such as the ability to survive gastrointestinal transit, modulate the host immune response, accumulate biopeptides in milk, and adhere to the epithelial cells that could contribute to improving host health. In this study, the applicability as functional cultures of four L. helveticus strains isolated from Italian hard cheeses was investigated. A preliminary strain characterization showed that the ability to produce folate was generally low while antioxidant, proteolytic, peptidase, and β-galactosidase activities resulted high, although very variable, between strains. When stimulated moDCs were incubated in the presence of live cells, a dose-dependent release of both the pro-inflammatory cytokine IL-12p70 and the anti-inflammatory cytokine IL-10, was shown for all the four strains. In the presence of cell-free culture supernatants (postbiotics), a dose-dependent, decrease of IL-12p70 and an increase of IL-10 was generally observed. The immunomodulatory effect took place also in Caciotta-like cheese made with strains SIM12 and SIS16 as bifunctional (i.e., immunomodulant and acidifying) starter cultures, thus confirming tests in culture media. Given that the growth of bacteria in the cheese was not necessary (they were killed by pasteurization), the results indicated that some constituents of non-viable bacteria had immunomodulatory properties. This study adds additional evidence for the positive role of L. helveticus on human health and suggests cheese as a suitable food for delivering candidate strains and modulating their anti-inflammatory properties.

Probiotic characterization of bacterial strains from fermented South Indian tomato pickle and country chicken intestine having antioxidative and antiproliferative activities

AIM

The present study aims to evaluate the potential antioxidant and antiproliferative properties of probiotic bacterial isolates Weissella cibaria p3B, Bacillus subtilis CS, and Bacillus tequilensis CL, isolated from South Indian fermented tomato pickle (homemade) and gut content of indigenous country chicken.

METHODS AND RESULTS

The bacterial isolates exhibited antimicrobial activity against food-borne, human pathogenic bacteria, along with better survival under different bile and acidic conditions, hydrophobicity towards several hydrocarbons, and adherence to intestinal epithelial cells (INT-407 cells). Also, the intact cell (IC) mixture of the three species showed better DPPH, ABTS, and Fe²⁺ chelating activity as compared to the individual IC or cell extract (CE) activity. Among the three bacterial species, W. cibaria p3B revealed maximum antiproliferative activity against HeLa and Caco-2 cancer cells, all of which were nontoxic to INT-407 cells. Apart from being non-hemolytic, the bacterial isolates did not display any necrotic inhibition in HeLa and Caco-2 cells. The cell free supernatant (CFS) of the three bacterial isolates were tested for the production of antimicrobial peptides or bacteriocins. It found that the CFS of bacterial isolates was stable at various temperature, pH and sensitive to proteolytic enzymes confirms protenoius in nature of the antimicrobil peptides or bacteriocins.

CONCLUSION

The bacterial isolates showed promising antimicrobial, antioxidant as well as antiproliferative activities with better survival ability at different pH and bile concentrations. The three bacterial isolates were able to produce potential antimicrobial peptides or bacteriocins.

SIGNIFICANCE AND IMPACT OF THE STUDY

These results indicate better compatibility of our bacterial isolates against synthetic drugs to avoid adverse side effects and can be processed as dietary supplements against food and human pathogens. They can also provide antioxidative and antiproliferative benefits to humans and animals.

Development of Antioxidant and Antihypertensive Properties during Growth of Lactobacillus helveticus, Lactobacillus rhamnosus and Lactobacillus reuteri on Cow's Milk: Fermentation and Peptidomics Study

Bioactive peptides derived from milk proteins are an active research area. Exhibiting numerous positive physiological effects on digestive, cardiovascular, immune and nervous systems, these peptides thought to be one of the most promising ingredients for functional food. Generally, these peptides are inactive within the parent proteins and can be liberated during milk fermentation by the specific proteolytic systems of various Lactobacillus spp. Here we present the study of milk fermentation by Lactobacillus helveticus NK1, Lactobacillus rhamnosus F and Lactobacillus reuteri LR1 strains. It was demonstrated that the antioxidant activity of the milk fermented by these strains concomitantly increased with the strains’ proteolytic activity. For the angiotensin I-converting enzyme (ACE) inhibitory activity, the same tendency was not observed. Although the proteolytic activity of L. helveticus NK1 was two times higher than that of L. rhamnosus F, the milk fermented by these strains showed comparable ACE inhibition. The analysis of the peptide profiles of the fermented milk samples allowed us to hypothesize that some previously unreported peptides can be produced by L. rhamnosus F. In addition, it was demonstrated that these potential ACE-inhibiting peptides originated from the C-terminus of α_S2-casein.

Consumer-perception, nutritional, and functional studies of a yogurt with restructured elderberry juice

We investigated the effects of supplementation of yogurt with elderberry juice (Sambucus nigra L.), in both natural and restructured forms, on certain technological, physicochemical, sensory, and health-promoting properties of yogurt, including antioxidant activity and inhibition of angiotensin-converting enzyme (ACE), α-amylase, and α-glucosidase activity. Consumer acceptance of the yogurt-juice products was assessed. Gel-strength restructured elderberry juice retained a spherical shape and most of the juice, despite decreasing in mass from 57.2 to 50.9 g during storage. As a result, yogurt supplemented with 10 and 25% restructured elderberry juice appeared to be more desirable from a sensory and technological perspective than yogurt with natural juice. Yogurt supplemented with restructured elderberry juice had a high water-holding capacity (94.4-96.4%), exhibited no spontaneous whey syneresis, and maintained a dense consistency (up to 5,626 g). Consumer penalty analysis of the just-about-right diagnostic attributes indicated that the flavor of these yogurts may not be sufficiently refreshing. High correlation was demonstrated between ACE inhibition, ABTS, α-amylase, and α-glucosidase in yogurt supplemented with restructured juice. An in vitro gastrointestinal simulation estimated bioaccessibility of antioxidants to be in the range of 62 to 66%. This model fermented yogurt supplemented with restructured elderberry juice is a novel dairy-juice beverage that represents a new approach for the development of functional fruit yogurt beverages.