pH-controlled fermentation in mild alkaline conditions enhances bioactive compounds and functional features of lentil to ameliorate metabolic disturbances

Lentil fermentation has a promising potential as a strategy for development of multifunctional ingredients targeting metabolic syndrome (MetS). Response surface methodology was applied to optimize lentil fermentation and study its effects on generation of peptides, soluble phenolics and bioactivities. Fermentation using Lactobacillus plantarum and Savinase® 16 L was carried out at different pH (6.5-8.5) and times (5.5-30 h). Analysis of variance was performed to evaluate linear, quadratic and interaction effects between fermentation parameters. pH positively affected peptides, soluble phenolic compounds and antioxidant activity whereas a negative impact on lipase inhibitory activity was observed (p < .0001). Time showed positive effect on proteolysis and negatively affected angiotensin I-converting enzyme inhibitory activity of fermented lentil (p < .0001). Multivariate optimization led to high levels of peptides, soluble phenolics and bioactivity of fermented lentil at pH 8.5 and 11.6 h. In conclusion, this study might contribute to the development of functional ingredients from lentil for MetS management.

Differential Gene Expression by Lactobacillus plantarum WCFS1 in Response to Phenolic Compounds Reveals New Genes Involved in Tannin Degradation

Lactobacillus plantarum is a lactic acid bacterium that can degrade food tannins by the successive action of tannase and gallate decarboxylase enzymes. In the L. plantarum genome, the gene encoding the catalytic subunit of gallate decarboxylase (lpdC, or lp_2945) is only 6.5 kb distant from the gene encoding inducible tannase (L. plantarumtanB [tanBLp ], or lp_2956). This genomic context suggests concomitant activity and regulation of both enzymatic activities. Reverse transcription analysis revealed that subunits B (lpdB, or lp_0271) and D (lpdD, or lp_0272) of the gallate decarboxylase are cotranscribed, whereas subunit C (lpdC, or lp_2945) is cotranscribed with a gene encoding a transport protein (gacP, or lp_2943). In contrast, the tannase gene is transcribed as a monocistronic mRNA. Investigation of knockout mutations of genes located in this chromosomal region indicated that only mutants of the gallate decarboxylase (subunits B and C), tannase, GacP transport protein, and TanR transcriptional regulator (lp_2942) genes exhibited altered tannin metabolism. The expression profile of genes involved in tannin metabolism was also analyzed in these mutants in the presence of methyl gallate and gallic acid. It is noteworthy that inactivation of tanR suppresses the induction of all genes overexpressed in the presence of methyl gallate and gallic acid. This transcriptional regulator was also induced in the presence of other phenolic compounds, such as kaempferol and myricetin. This study complements the catalog of L. plantarum expression profiles responsive to phenolic compounds, which enable this bacterium to adapt to a plant food environment.IMPORTANCELactobacillus plantarum is a bacterial species frequently found in the fermentation of vegetables when tannins are present. L. plantarum strains degrade tannins to the less-toxic pyrogallol by the successive action of tannase and gallate decarboxylase enzymes. The genes encoding these enzymes are located close to each other in the chromosome, suggesting concomitant regulation. Proteins involved in tannin metabolism and regulation, such GacP (gallic acid permease) and TanR (tannin transcriptional regulator), were identified by differential gene expression in knockout mutants with mutations in genes from this region. This study provides insights into the highly coordinated mechanisms that enable L. plantarum to adapt to plant food fermentations.

Identification, functional gastrointestinal stability and molecular docking studies of lentil peptides with dual antioxidant and angiotensin I converting enzyme inhibitory activities

The objective was to identify peptides with dual antioxidant and angiotensin I converting enzyme (ACE) inhibitory activities released from lentil proteins by Savinase®. The influence of gastrointestinal digestion on peptide bioactivity was also assayed. Fragments from vicilin, convicilin and legumin were the most abundant peptides identified. Peptides LLSGTQNQPSFLSGF, NSLTLPILRYL, TLEPNSVFLPVLLH showed the highest antioxidant (0.013-1.432μmol Trolox eq./μmol peptide) and ACE inhibitory activities (IC₅₀=44-120μM). Gastrointestinal digestion of peptides improved their dual activity (10-14μmol Trolox eq./μmol peptide; IC₅₀=11-21μM). In general, C-terminal heptapeptide was crucial for their dual activity. ACE inhibition relies on the formation of hydrogen bonds between C-terminal residues of lentil peptides and residues of the ACE catalytic site. The present study helps clarifying the relationship between structure and dual antioxidant/antihypertensive activity of lentil peptides opening new opportunities to food industry such as the application of lentil protein hydrolysates as ingredients for development of functional foods.

High-Pressure-Assisted Enzymatic Release of Peptides and Phenolics Increases Angiotensin Converting Enzyme I Inhibitory and Antioxidant Activities of Pinto Bean Hydrolysates

Pinto bean protein concentrate was hydrolyzed by subtilisins at 0.1, 100, and 200 MPa and 50 °C for 15 min. Alcalase hydrolysis at 100 MPa led to higher ACE inhibition, reducing power, and free radical scavenging activity of hydrolysates. However, hydrolysate obtained by Savinase at 200 MPa showed the best ACE-inhibitory and radical scavenging activities. Proteolysis by Savinase at 200 MPa was considered the most effective treatment to increase small peptides (<3 kDa), flavonoids, total phenolic compounds, and oxygen radical absorbance capacity in hydrolysates. In this hydrolysate, small phaseolin fragments with reported ACE-inhibitory and antioxidant sequences were identified. Catechin, pelargonidin 3-glucoside, and ferulic acid were the main phenolic compounds. Hihg-pressure-assisted hydrolysis of common bean protein concentrates would provide benefits in the production of functional hydrolysates providing higher functionality and added value to the resulting hydrolysate due to synergistic effects of bioactive peptides and soluble phenolics.

Impact of Elicitation on Antioxidant and Potential Antihypertensive Properties of Lentil Sprouts

The aim of this study was to investigate the application of elicitors (500 μM ascorbic acid, 50 μM folic acid, 5 mM glutamic acid and 50 ppm chitosan in 5 mM glutamic acid) during lentil germination up to 8 days as a strategy to increase germination rate and to enhance the accumulation of γ-aminobutyric acid (GABA) and phenolic compounds. The effect of elicitation on the protein profile and antioxidant and angiotensin I converting enzyme (ACE) inhibitory activities of sprouted lentils was also evaluated. The application of elicitors did not negatively affect the germination yield of lentils and no significant changes on the protein pattern of lentils germinated in the presence of elicitors were observed. Chitosan/glutamic acid increased by 1.6-fold the GABA content in lentil sprouts, whilst ascorbic and folic acids as well as chitosan/glutamic acid were highly effective to enhance the total content of phenolic compounds and the antioxidant activity of sprouted lentils. All elicited lentil sprouts showed ability to inhibit ACE activity (IC50: 9.5-11.9 μg peptides/mL). Therefore, elicitation can be considered a promising approach to improve the content of compounds with antioxidant and potential antihypertensive activities in lentil sprouts.

Allergenic proteins in enology: a review on technological applications and safety aspects

Proteinaceous products are widely used as fining agents during winemaking to remove unwanted insoluble particles and undissolved microscopic particles (colloidal material) from the must or wine to improve stability. Some of them (egg white, caseinates, and fish gelatine) have allergenic potential and the presence of their residues in the final product could represent a risk for allergic individuals. Moreover, lysozyme (an egg allergen) is included among wine additives to control the fermentation processes and avoid spoiling during winemaking. The aim of this paper is to review the experimental/clinical data on the use of allergenic products in enology and the measurement of relative risk for sensitized subjects. In addition, methods developed specifically for the quantification of allergenic residues in must and wine are described.

Molecular characterization of allergens in raw and processed kiwifruit

BACKGROUND

The prevalence of allergy to kiwifruit is increasing in Europe since the last two decades. Different proteins have been identified as kiwifruit allergens; even though with geographic differences, Act d 1, a cysteine protease protein of 30 kDa, and Act d 2, a thaumatin-like protein of 24 kDa, are normally considered the most important. The aim of this study was (i) to identify at molecular level the sensitization pattern in a group of well-characterized patients allergic to kiwifruit and (ii) to assess the role of technological treatments on kiwifruit allergenic potential.

METHODS

The differences in the pattern of antigenicity between fresh and processed kiwifruit were evaluated by both immunoelectrophoretic techniques and clinical tests.

RESULTS

In the group of patients included in this study, three proteins were identified as major allergens in fresh kiwifruit, as the specific sensitization was present in ≥50% of the subjects. These proteins corresponded to actinidin (Act d 1), pectin methyl aldolase (Act d 6), and thaumatin-like protein (Act d 2). Kiwellin (Act d 5) and proteins of Bet v 1 family (Act d 8/act d 11) were also recognized as minor allergens. Immunoreactivity was totally eliminated by industrial treatments used for the production of kiwifruit strained derivative.

CONCLUSIONS

In this group of allergic children, the technological treatments used in the production of kiwifruit strained product reduced drastically the allergenic potential of kiwifruit.

A multistrategic approach in the development of sourdough bread targeted towards blood pressure reduction

Rising prevalence of hypertension is pushing food industry towards the development of innovative food products with antihypertensive effects. The aim was to study the effect of reduced sodium content and 21% addition of wholemeal wheat sourdough (produced by Lactobacillus brevis CECT 8183 and protease) on proximate composition, γ-aminobutyric acid (GABA) and peptide content of wheat bread. Angiotensin converting enzyme I (ACE) inhibitory and antioxidant activities were also evaluated. Sodium replacement by potassium salt did not affect chemical composition and biological activities of bread. In contrast, GABA and peptides <3 kDa contents in sourdough bread (SDB) were 7 and 3 times higher, respectively, than the observed in control. ACE inhibitory and antioxidant activities of the peptide fraction < 3 kDa from SDB was 1.7 and 2.6-3.0 times higher than control. Therefore, the combination of reduced sodium content with enriched concentrations of bioactive compounds in bread making may provide interesting perspectives for development of innovative breads towards blood pressure reduction.

Biochemical and immunochemical evidences supporting the inclusion of quinoa (Chenopodium quinoa Willd.) as a gluten-free ingredient

To date, the only acceptable therapeutic approach for celiac disease (CD) is a strict elimination from the diet of gluten-containing foods, but this diet does not always guarantee an adequate nutritional intake. Pseudocereals are receiving considerable attention as interesting alternatives for the formulation of gluten-free products, and quinoa grains arise as nutritive substitutes of conventional cereals. The aim of this study was the characterization of different quinoa samples corresponding to 11 quinoa varieties, using polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate (SDS-PAGE) and immunoblotting techniques to assess their suitability for celiac subjects. Some of these varieties were grown in Italy to assess if the reproduction in a new habitat can guarantee the retention of the "safe" protein pattern. None of the quinoa varieties studied presented protein bands with electrophoretic mobility comparable with those of wheat gliadins, the toxic protein for celiac subjects. All the quinoa samples showed a low binding affinity for both specific anti-gliadin antibodies and IgAs from celiac subjects, confirming that quinoa can be considered as a safe ingredient for celiac patients. However, reliable varieties should be previously selected since the immuno cross-reactivity with anti-gliadin antibodies can vary significantly.

Synthesis of [(77)Se]-methylselenocysteine when preparing sauerkraut in the presence of [(77)Se]-selenite. Metabolic transformation of [ (77)Se]-methylselenocysteine in Wistar rats determined by LC-IDA-ICP-MS

The use of enriched Se isotopes as tracers has provided important information on Se metabolism. However, selenium isotopes are expensive and difficult to obtain. A simple and cheap strategy based on the production of [(77)Se]-methylselenocysteine ([(77)Se]-MeSeCys) when preparing sauerkraut in the presence of [(77)Se]-selenite was developed. The resulting [(77)Se]-MeSeCys was used for evaluating the metabolic transformation of MeSeCys in Wistar rats, by feeding them with an AIN-93 M diet containing 20 % sauerkraut enriched in [(77)Se]-MeSeCys. Organs (liver, kidney, brain, testicles, and heart) were obtained after seven days of treatment and subjected to total selenium and selenium-speciation analysis by high-performance liquid chromatography coupled with isotope-dilution-analysis inductively-coupled-plasma mass spectrometry (HPLC-IDA-ICP-MS). Analysis of (77)Se-labeled organs revealed a prominent increase (more than 100 % Se-level enhancement) of selenium in the kidney and heart, whereas in the liver selenium concentration only increased by up to 20 % and it remained constant in the brain and testicles. (77)Se-enriched-sauerkraut supplementation does not alter the concentration of other essential elements in comparison to controls except for in the heart and kidney, in which selenium was positively correlated with Mg, Zn, Cu, and Mo. HPLC-ICP-MS analysis of hydrolyzed extracts after carbamidomethylation of the (77)Se-labeled organs revealed the presence of [(77)Se]-SeCys and an unknown Se-containing peak, the identity of which could not be verified by electrospray-ionization (ESI)-MS-MS. Low amounts of [(77)Se]-MeSeCys were found in (77)Se-labeled liver and kidney extracts, suggesting the incorporation of this selenium species in its intact form.

Fermentation enhances the content of bioactive compounds in kidney bean extracts

The influence of solid (SSF) or liquid state fermentation (LSF) for 48 and 96 h on the production of water soluble extracts from kidney beans was investigated. SSF was carried out by Bacillus subtilis, whilst LSF was performed either by natural fermentation (NF) or by Lactobacillus plantarum strain (LPF). SSF extracts showed high soluble phenolic compound content (31-36 mg/g) and antioxidant activity (508-541 μg trolox equivalents/g), whilst LSF extracts exhibited potential antihypertensive activity due to their large γ-aminobutyric acid (GABA) content (6.8-10.6 mg/g) and angiotensin converting enzyme inhibitory (ACEI) activity (>90%). Therefore, fermentation can be considered as a valuable process to obtain bioactive ingredients from kidney beans, which could encourage their utilisation in the formulation of added-value functional foods.

Savinase, the most suitable enzyme for releasing peptides from lentil (Lens culinaris var. Castellana) protein concentrates with multifunctional properties

The aim of this study was to produce multifunctional hydrolysates from lentil protein concentrates. Four different proteases (Alcalase, Savinase, Protamex, and Corolase 7089) and different hydrolysis times were evaluated for their degree and pattern of proteolysis and their angiotensin I-converting enzyme (ACE) inhibitory and antioxidant activities. Alcalase and Savinase showed the highest proteolytic effectiveness (P ≤ 0.05), which resulted in higher yield of peptides. The hydrolysate produced by Savinase after 2 h of hydrolysis (S2) displayed the highest ACE-inhibitory (IC50 = 0.18 mg/mL) and antioxidant activity (1.22 μmol of Trolox equiv/mg of protein). Subsequent reverse-phase HPLC-tandem mass spectrometric analysis of 3 kDa permeates of S2 showed 32 peptides, mainly derived from convicilin, vicilin, and legumin containing bioactive amino acid sequences, which makes them potential contributors to ACE-inhibitory and antioxidant activities detected. The ACE-inhibitory and antioxidant activities of S2 were significantly improved after in vitro gastrointestinal digestion (P ≤ 0.05). Multifunctional hydrolysates could encourage value-added utilization of lentil proteins for the formulation of functional foods and nutraceuticals.

Extruded flaxseed meal enhances the nutritional quality of cereal-based products

Human consumption of flaxseed is increasing due to its health benefit properties and extrusion processes can enhance its nutritional quality. Extruded flaxseed meal (EFM) obtained in a pilot plant was characterized and incorporated in flour mixes and cereal-based bars to demonstrate its nutritious usefulness. Amino acid content was not affected by extrusion and, despite lysine was the limitating amino acid, the chemical score (CS) was 83 %. Thiamin and riboflavin decreased slightly as consequence of extrusion, phytic acid did not change and trypsin inhibitor activity was undetectable. Proximate composition and nutritional quality determined by biological and chemical indexes were compared among EFM, flour mixes (FM) and cereal bars (CB). They presented high protein levels (26, 20 and 17 %, respectively), good biological value (BV) (80, 79 and 65, respectively), acceptable true protein digestibility (TD) (73, 79 and 78, respectively), and high dietary fiber (33, 20.5 and 18 %, respectively). The ratio of ω6:ω3 for CB was within the WHO/FAO recommendations. These results open a new venue for the usefulsess of nutritious/healthy extruded flaxseed flours into ready-to-eat cereal-based products with improved nutritional quality.