Effect of a Probiotic Beverage Enriched with Cricket Proteins on the Gut Microbiota: Composition of Gut and Correlation with Nutritional Parameters.

The health and balance of the gut microbiota are known to be linked to diet composition and source, with fermented products and dietary proteins potentially providing an exceptional advantage for the gut. The purpose of this study was to evaluate the effect of protein hydrolysis, using a probiotic beverage enriched with either cricket protein (CP) or cricket protein hydrolysates (CP.Hs), on the composition of the gut microbiota of rats. Taxonomic characterization of the gut microbiota in fecal samples was carried out after a 14-day nutritional study to identify modifications induced by a CP- and CP.H-enriched fermented probiotic product. The results showed no significant differences (p > 0.05) in the diversity and richness of the gut microbiota among the groups fed with casein (positive control), CP-enriched, and fermented CP.H-enriched probiotic beverages; however, the overall composition of the microbiota was altered, with significant modifications in the relative abundance of several bacterial families and genera. In addition, fermented CP.H-enriched probiotic beverages could be related to the decrease in the number of potential pathogens such as Enterococcaceae. The association of gut microbiota with the nutritional parameters was determined and the results showed that digestibility and the protein efficiency ratio (PER) were highly associated with the abundance of several taxa.

Influence of growth parameters on bacteriocin-like inhibitory substances (BLIS) production by lactic acid bacteria.

This study aimed to investigate the possible production of bacteriocin-like inhibitory substances (BLIS) and optimize it by Lactobacillus sakei and combined Lactobacillus curvatus/Pediococcus acidilactici, lactic acid bacteria used for the meat fermentation. The effect of growth parameters on BLIS production was evaluated by measuring the antibacterial activity of the cell-free supernatant of these bacteria. The stability of the cell-free supernatant of combined L.curvatus/P.acidilactici bacteria was also examined after heat treatment and pH variations. Results showed highest BLIS production by L.curvatus/P.acidilactici was at growth temperatures of 28°C and pH 5, while the optimum condition for production of BLIS by L.sakei was 24°C and pH 6.5. The BLIS production by L. curvatus/P. acidilactici bacteria was greatly influenced by carbon and nitrogen sources. The antimicrobial activity of BLIS in supplemented De Man, Rosa, and Sharpe broth (MRS) was 2044.44 AU/mL, 4.84-fold greater than unsupplemented MRS. None of the carbon sources used in this study affected the BLIS production by the L.sakei, while pea peptone enhanced the antimicrobial activity and showed a value of 188.89 AU/mL, 1.47-fold greater than unsupplemented MRS. The characterization of the cell-free supernatant of L. curvatus/P. acidilactici bacteria showed the heat stability and activity of BLIS at pH 2-10.

Food grade nanoemulsion development to control food spoilage microorganisms on bread surface.

In this study, the effect of emulsifier mixture and their concentrations on the development of nanoemulsion was studied. The impact of sonication and microfluidization processing conditions on the physicochemical properties and in vitro antimicrobial activity was also evaluated. The optimal nanoemulsion formulation was then evaluated on bread surface against B. subtilis. Results showed that a hydrophilic-lipophilic balance HLB = 12 and emulsifier: oil ratio of 1:1 allowed the formation of stable nanoemulsion. Also, both microfluidization and sonication allowed the formation of nanoscale-emulsion. Sonication treatment for 10 min allowed a maintain the total flavonoid content and a slight reduction of total phenol content. Furthermore, employing sonication resulted to the lowest polydispersity index suggesting more stable nanoemulsion. Nanoscale-emulsion showed a good in vitro antimicrobial activity against L. monocytogenes and E. coli. The application of nanoemulsion on bread surface inoculated with B. subtilis showed a delay of the decay. Supplementary Information: The online version contains supplementary material available at 10.1007/s13197-022-05660-5.

Development of a natural antifungal formulation for grated cheese and a microencapsulation approach using whey protein isolate and maltodextrin blend.

The antifungal activity of natural antimicrobials such as essential oils (EOs), citrus extracts, and other natural derivatives was evaluated against 10 fungal strains using minimum inhibitory concentration (MIC) analysis. Compounds having the highest inhibitory activity at the lowest concentrations were subsequently selected to evaluate the possible synergistic interactions by checkerboard method (FIC). The results showed that citrus extract A (CEA) and EOs rich in cinnamaldehyde had the highest inhibitory capacity against evaluated strains (Aspergillus niger, Aspergillus versicolor, Aureobasidium pullulans, Eurotium rubrum, Paecilomyces spp., Penicillium chrysogenum, Penicillium citrinum, Penicillium commune, Penicillium crustosum, and Penicillium roqueforti). The stability of the antifungal mixture was then optimized using lecithin and sucrose monopalmitate (SMP) as surfactants. Stability test showed that lecithin:SMP at HLB 10 maintains emulsion stability for 15 days of storage at 4°C. Encapsulation process for the loaded emulsion was optimized using whey protein isolate (WPI) and maltodextrin (MD) blend with ratios WPI:MD (1:2) and WPI:MD (1:3). The results showed that WPI:MD (1:3) led to a higher physicochemical stability (-40.5 mV), encapsulation efficiency (91%), and antifungal activity (315 ppm). Microencapsulation maintained the available active compounds content more prolonged with an average interval of 7 days compared to the nonencapsulated formulations during storage at 4°C.

Physico-chemical Properties and Sensorial Appreciation of a New Fermented Probiotic Beverage Enriched with Pea and Rice Proteins.

OBJECTIVES: The purpose of this study was to evaluate the physico-chemical stability, the sensorial properties, and the microbial quality of a fermented beverage enriched with pea and rice proteins (PRF) during storage at 4 °C. To investigate the effect of the protein enrichment and fermentation, the PRF beverage quality was compared with non-fermented and non-enriched beverages. METHODS: The beverage was supplemented with a 50/50 mixture of pea and rice protein concentrate to 13% concentration. Following inoculation with 108 CFU/mL of lactic acid bacteria, it was incubated at 37 °C for 14 h. RESULTS: Results showed that the enrichment with protein induced an increase in pH, titratable acidity and viscosity of the PR products, while the fermentation led to a decrease of pH and viscosity. However, a significant increase of the viscosity of PRF from 39 to 57 cP was observed during the 143 days of storage (P ≤ 0.05). The PRF beverage contained significantly more peptides < 200 Da than the non-fermented one (PRNF) and these small peptides were also released during the storage. Despite the physico-chemical modifications, the sensorial properties of the PRF product were appreciated over the storage, particularly for the texture. Furthermore, the beverage maintained a high concentration of viable probiotics during the entire storage with 8.4 log colony form unit (CFU)/mL after 143 days. CONCLUSION: Applying probiotics and the mixture of rice and pea proteins in the fermented beverage can enhance nutritional and nutraceutical value of the product.

Silver nanoparticles-essential oils combined treatments to enhance the antibacterial and antifungal properties against foodborne pathogens and spoilage microorganisms.

Plant-derived essential oils (EOs) and commercial silver nanoparticles (AgNPs) were tested to evaluate their antibacterial and antifungal efficiency against two pathogenic bacteria (Escherichia coli O157:H7 and Salmonella Typhimurium) and three spoilage fungi (Aspergillus niger, Penicillium chrysogenum, and Mucor circinelloides). A broth microdilution assay was used to determine the minimal inhibitory concentration (MIC) of EOs and AgNPs. In the MIC assay, the cinnamon EO, Mediterranean formulation, citrus EO and spherical-shaped silver nanoparticles (AgNPs) (AGC 1, AGC 0.5, AGPP and AGPPH) showed moderate to high antibacterial and antifungal properties, with MIC ranging from 7.8 to 62.5 ppm for AgNPs and 312.5-1250 ppm for EOs against the tested bacteria and fungi. The possible interaction between the EOs and the AgNPs was determined using a checkerboard method by evaluating fractional inhibitory concentration (FIC) values. The combination of two or more EOs and AgNPs (Active combination 1: AGPPH+cinnamon EO, Active combination 2: AGC 0.5+Mediterranean formulation+citrus EO, Active combination 3: AGPP+cinnamon EO+Asian formulation+lavang EO) showed synergistic effects (FIC <1.0) against all tested bacteria and fungi. A modified Gompertz model was used to evaluate growth parameters including maximum colony diameter (A), maximum growth rate (Vm), and lag phase (λ), under the three active combinations suggested by the checkerboard method using a vapor assay. The three active combinations 1, 2 and 3 reduced the growth rate and maximum colony diameter of E. coli, S. Typhimurium, A. niger, P. chrysogenum, and M. circinelloides, and extended their lag phase from 1 to 5 days. In in situ tests with inoculated rice, the three active combinations showed a significant reduction of all tested bacteria and fungi at 27 °C for 28 days.

Efficiency of milk proteins in eliminating practical limitations of ß-carotene in hydrated polar solution.

The objective of this work was to study ß-carotene functionalities (color and antioxidant activity) and practical limitations (aggregate formation, poor solubility and low stability) when included in the aqueous systems containing milk proteins. According to the results, self-association constant of ß-carotene in the presence of casein is 1.7-fold of that calculated for WPI. Casein and WPI were capable of conserving ß-carotene against chemical oxidation up to 15 and 12%, respectively, at 1:5 M ratio of ß-carotene to protein. While, WPI reduced its photodegradation quantum yield from 0.03 to 0.012 compared to 0.017 obtained for casein. A 2.7- and 3.6-fold enhancement in ß-carotene solubility was observed in the presence of 1.5 mg/mL of casein and WPI, respectively. The study of ß-carotene interaction with proteins showed, on the one hand, a negative effect on electron transfer and, on the other hand, improved hydrogen transfer to the radical species in the solution.

Binding of ß-carotene to whey proteins: Multi-spectroscopic techniques and docking studies.

The objective of this work was to study molecular binding between ß-carotene (ß-C) and whey protein isolate (WPI) as a function of pH (4-9), temperature (15, 25, and 35 °C), and NaCl concentration (0-0.25 M) using spectroscopic techniques and docking studies. The fluorescence quenching data showed that binding affinity increased with pH, temperature and ionic strength. The binding was entropy driven and involved mostly hydrophobic interactions. Three major whey proteins including ß-lactoglobulin (ß-Lg), α-lactalbumin (α-Lac), and bovine serum albumin (BSA) were bound to ß-C with overall binding constant values of 1.31 × 107, 1.80 × 104, and 4.51 × 104 M-1, respectively. A single class of binding sites for ß-C on whey fractions was recognized using Job's method. Docking results revealed ß-C was bound to the subdomain IIA of BSA, the residues of aromatic cluster II in α-lactalbumin and into the calyx of ß-lactoglobulin resulting in conformational changes in the secondary and tertiary structures of proteins.

Spectroscopic and docking studies on the interaction between caseins and ß-carotene.

Natural occurrence of ß-carotene in bovine milk and the leading role of milk proteins in low-fat or fat-free dairy products necessitate investigating the possibility of interaction between ß-carotene and casein constituting up to 80% of bovine milk proteins. In this study, molecular interaction of caseins and ß-carotene was analyzed using fluorescence, UV-Vis absorption, circular dichroism (CD), and computer-aided molecular modeling. Casein and its fractions were bound to ß-carotene with a binding constant of the order 104 M-1 and a 1:1 binding stoichiometry. The binding was favored at alkaline pHs, low ionic strength and temperatures. κ-Casein had the highest binding affinity to ß-carotene, among casein fractions. The negative values of entropy and enthalpy changes and docking studies proved Van der Waals interactions are predominant forces in the binding process. The casein conformation was also altered through inducing a more folded structure in ß-casein and a looser conformation in α- and κ-casein.