Interactions between Lactobacillus acidophilus strains and the starter cultures, Lactobacillus bulgaricus and Streptococcus thermophilus during fermentation of goats’ milk

It has been observed that Lactobacillus acidophilus has poor survivability in fermented goats’ milk. In this study, interactions between L. acidophilus and starter cultures during goats’ milk fermentation were investigated using three strains of L. acidophilus: ATCC-11975, LA-5 and NCFM, and the starter cultures (Lactobacillus delbrueckii subsp. bulgaricus (LB350) and Streptococcus thermophilus (ST350), isolated from a commercial yogurt starter. Selective enumeration methods were validated; de Mann, Rogosa and Sharpe (MRS) agar with 0.2% bile and anaerobic incubation at 37°C (72 h) was found to be suitable for all L. acidophilus strains; MRS agar with pH adjusted to 5.2 and anaerobic incubation at 37°C (24 h) was used for strain LB350 and M17 agar with 0.5% lactose and aerobic incubation at 37°C (24 h) for strain ST350. Addition of LB350 and/or ST350 into the goats’ milk inoculated with L. acidophilus strains accelerated pH decrease compared to L. acidophilus strains used alone. Antagonism between each of the L. acidophilus strains and LB350 occurred, most noticeably with the LA-5 culture. However, it varied widely between the acidophilus strains indicating that antagonism is likely to be strain specific.Keywords: Lactobacillus acidophilus, Lactobacillus delbrueckii subsp. bulgaricus, Streptococcus thermophilus, interactions, goats’ mil

Physicochemical and functional properties, microstructure, and storage stability of whey protein/polyvinylpyrrolidone based glue sticks

A glue stick is comprised of solidified adhesive mounted in a lipstick-like push-up tube. Whey is a byproduct of cheese making. Direct disposal of whey can cause environmental pollution. The objective of this study was to use whey protein isolate (WPI) as a natural polymer along with polyvinylpyrrolidone (PVP) to develop safe glue sticks. Pre-dissolved WPI solution, PVP, sucrose, 1,2-propanediol (PG), sodium stearate, defoamer, and preservative were mixed and dissolved in water at 90 oC and then molded in push-up tubes. Chemical composition, functional properties (bonding strength, glue setting time, gel hardness, extension/retraction, and spreading properties), microstructure, and storage stability of the prototypes were evaluated in comparison with a commercial control. Results showed that all WPI/PVP prototypes had desirable bonding strength and exhibited faster setting than PVP prototypes and control. WPI could reduce gel hardness and form less compact and rougher structures than that of PVP, but there was no difference in bonding strength. PVP and sucrose could increase the hygroscopicity of glue sticks, thus increasing storage stability. Finally, the optimized prototype GS3 (major components: WPI 8.0%, PVP 12.0%, 1,2-propanediol 10.0%, sucrose 10.0%, and stearic sodium 7.0%) had a comparable functionality to the commercial control. Results indicated that whey protein could be used as an adhesive polymer for glue stick formulations, which could be used to bond fiber or cellulose derived substrates such as paper

Comparative proteomics of human milk casein fraction collected from women of Korean and Han ethnic groups in China

IntroductionHuman breast milk provides neonates with indispensable nutrition and function. Milk protein is one of the main constituents of breast milk. Human milk profiles can be influenced by many factors.MethodsThe present study aimed to investigate the difference in casein isolated from mature milk of healthy mothers of Korean and Han ethnic groups in China using data-independent acquisition (DIA) proteomics.ResultsA total of 535 proteins were identified and quantified in casein fraction samples from both groups. A total of 528 proteins were annotated to 52 Gene Ontology (GO) terms, the majority (94.13%) of which were distributed in the cell and cell parts of the cellular component. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis revealed that 106 proteins were involved in 23 pathways, the greatest (36.79%) in carbohydrate metabolism. There were 39 differentially expressed proteins (DEPs)–10 upregulated and 29 downregulated–between Korean and Han milk. The GO function of blood microparticles and KEGG pathway of Staphylococcus aureus infection for DEPs were the most significantly enriched (p < 0.05). Protein-protein interaction analysis revealed a network with 23 DEPs in 47 interactions, and the fibrinogen alpha chain ranked first as the hub protein.DiscussionThese data may provide useful technical guidance for the development of specific infant foods for certain populations

Milk Protein Polymer and Its Application in Environmentally Safe Adhesives

Milk proteins (caseins and whey proteins) are important protein sources for human nutrition; in addition, they possess important natural polymers. These protein molecules can be modified by physical, chemical, and/or enzymatic means. Casein is one of the oldest natural polymers, used for adhesives, dating back to thousands years ago. Research on milk-protein-based adhesives is still ongoing. This article deals with the chemistry and structure of milk protein polymers, and examples of uses in environmentally-safe adhesives. These are promising routes in the exploration of the broad application of milk proteins

Stability of lutein encapsulated whey protein nano-emulsion during storage.

Lutein is a hydrophobic carotenoid that has multiple health functions. However, the application of lutein is limited due to its poor solubility in water and instability under certain conditions during storage. Hereby we generated lutein loaded nano-emulsions using whey protein isolate (WPI) or polymerized whey protein isolate (PWP) with assistance of high intensity ultrasound and evaluate their stability during storage at different conditions. We measured the particle size, zeta-potential, physical stability and lutein content change. Results showed that the PWP based nano-emulsion system was not stable in the tested Oil/Water/Ethanol system indicated by the appearance of stratification within only one week. The WPI based nano-emulsion system showed stable physiochemical stability during the storage at 4°C. The lutein content of the system was reduced by only 4% after four weeks storage at 4°C. In conclusion, our whey protein based nano-emulsion system provides a promising strategy for encapsulation of lutein or other hydrophobic bioactive molecules to expand their applications

Effects of Radiation on Cross-Linking Reaction, Microstructure, and Microbiological Properties of Whey Protein-Based Tissue Adhesive Development

Whey proteins are mainly a group of small globular proteins. Their structures can be modified by physical, chemical, and other means to improve their functionality. The objectives of this study are to investigate the effect of radiation on protein–protein interaction, microstructure, and microbiological properties of whey protein–water solutions for a novel biomaterial tissue adhesive. Whey protein isolate solutions (10%, 27%, 30%, 33%, and 36% protein) were treated by different intensities (10–35 kGy) of gamma radiation. The protein solutions were analyzed for viscosity, turbidity, soluble nitrogen, total plate count, and yeast and mold counts. The interactions between whey proteins were also analyzed by sodium dodecyl sulfate polyacrylamide gel electrophoresis and scanning electron microscopy. The viscosity of protein solution (27%, w/w) was increased by the treatment of gamma radiation and by the storage at 23 °C. The 35 kGy intensity irradiated soluble nitrogen (10%, w/w) was reduced to about half of the sample treated by 0 kGy gamma radiation. The effects of gamma radiation and storage time can significantly increase the viscosity of whey protein solutions (p p < 0.05). SDS-PAGE results show that the extent of oligomerization of whey protein isolate solutions are increased by the enhancement in gamma radiation intensity. Photographs of SEM also indicate that protein–protein interactions are induced by gamma radiation in the model system. Consistent with above results, the bonding strength increases by the addition of extent of gamma radiation and the concentration of glutaraldehyde. Our results revealed that the combination of gamma-irradiated whey protein isolate solutions and glutaraldehyde can be used as a novel biomaterial tissue adhesive

Effects of Ultrasound Treatment on Extraction and Rheological Properties of Polysaccharides from Auricularia Cornea var. Li.

Auricularia cornea var. Li. is an edible fungi and polysaccharides in Auricularia cornea var. Li. may have bioactive activities. Polysaccharides from Auricularia cornea var. Li. (ACP) was extracted using ultrasound-assisted extraction (UAE) method and compared with hot water extraction (HWE) for extraction yield, extraction rate, purity of polysaccharides, microstructure of residues after extraction, preliminary structure and rheological properties of polysaccharides. Optimum conditions for UAE (particle size of 150&ndash;200 mesh, water to raw material ratio of 70:1, extraction temperature at 70 &deg;C for 40 min, ultrasonic amplitude of 40%) and HWE (particle size of 150&ndash;200 mesh, water to raw material ratio of 60:1, extraction temperature at 90 &deg;C for 3.0 h) were obtained via single-factor experiment. Under optimum conditions, extraction yield of polysaccharides by UAE was 30.99 &plusmn; 1.93% which showed no significant difference with that by HWE (30.35 &plusmn; 1.67%) (P &gt; 0.05). Extraction rate (29.29 &plusmn; 1.41%) and purity (88.62 &plusmn; 2.80%) of polysaccharides by UAE were higher than those by HWE (extraction rate of 24.95 &plusmn; 2.78% and purity of 75.33 &plusmn; 6.15%) (P &lt; 0.05). Scanning Electron Microscopy (SEM) images of residues by UAE showed more broken cells than those by HWE. Fourier Transform Infrared (FTIR) spectra showed that the dialyzed ACP extracted by HWE and UAE (DACP-HWE and DACP-UAE) had similar characteristic absorption peaks of polysaccharides. Both DACP-HWE and DACP-UAE solutions showed typical shear thinning and temperature-independent behaviors (25&ndash;90 &deg;C) and UAE resulted in polysaccharides with remarkably lower viscosity in comparison with HWE. DACP-UAE solutions exhibited more liquid-like state while DACP-HWE solutions solid-like system. Data indicated that ultrasound treatment may be a useful means for extraction of polysaccharides from Auricularia cornea var. Li

Use of Whey Protein as a Natural Polymer for Tissue Adhesive: Preliminary Formulation and Evaluation In Vitro

The use of sutures is still the most widely practiced solution for wound closure and tissue reconstruction; however, scarring is a common defect resulting from sutures on topical use. In some cases, the conventional sutures are unable to seal the sites where fluid and air leakage could occur. Tissue adhesives though have lower tensile strength than sutures, may make scarless surgery possible, or prevent fluid and air leakage. A product called BioGlue&reg; (CryoLife Inc, Kennesaw, GA, USA), based on bovine serum albumin (BSA, a protein) and glutaraldehyde (GTA, crosslinker), has been approved for clinical use in the USA. Whey protein, a byproduct of cheese-making, comprised mainly of &beta;-lactoglobulin, &alpha;-lactalbumin and BSA. Even though the molecular weight of BSA is about three times larger than the molecular of &beta;-lactoglobulin and &alpha;-lactalbumin, all three proteins are rich in free &epsilon;-amino groups (can react with GTA) and globular proteins. This similarity make whey protein a potential candidate to replace BSA in the tissue adhesive since whey protein is abundant and much cheaper than BSA. In this study, whey protein isolate (WPI) was used as a protein polymer with GTA as a crosslinker to evaluate the feasibility of whey protein for tissue adhesive formulation. Results showed that the WPI/GTA adhesive exhibited a comparable adhesive strength to BioGlue&reg; control

Effect of ultrasound treatment on antioxidant activity and structure of β-Lactoglobulin using the Box–Behnken design

Effect of ultrasound treatment on antioxidant activity and structure of β-Lactoglobulin were investigated using antioxidant indexes and spectroscopy techniques. The 1,1-Diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activities had been applied to the experimental response obtained by a three-factor-three-level Box–Behnken design. Results showed that ultrasound treatment significantly increased antioxidant activity (p < 0.05). The maximum DPPH radical scavenging activity of β-Lactoglobulin was 57.59% at the ultrasound conditions of 45°C, 20 min and amplitude of 30%. The ultrasound-treated β-Lactoglobulin exhibited higher 2,2ʹ-Azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt radical scavenging activity and oxygen radical absorbance capacity. Circular dichroism data indicated that ultrasound treatment increased both α-helix and β-sheet contents of β-Lactoglobulin and altered Trp residues, which resulted in the secondary and tertiary structure changes. Differential scanning calorimeter and scanning electron microscopy micrographs showed that ultrasound-treated β-Lactoglobulin contained larger aggregates than untreated. In conclusion, ultrasound treatment had considerable effects on antioxidant activity and structure of β-Lactoglobulin. Ultrasound treatment may expand the applications of β-Lactoglobulin in food industries

Ultrasound‐induced changes in structural and physicochemical properties of β‐lactoglobulin

Effect of ultrasound treatment on the physicochemical properties and structure of β‐lactoglobulin were investigated. β‐Lactoglobulin was treated with ultrasound at different amplitudes, temperatures, and durations. The surface hydrophobicity and free sulfhydryl group of β‐lactoglobulin were significantly increased after ultrasound treatment (p &lt; .05). The maximal surface hydrophobicity and free sulfhydryl group were 5,812.08 and 5.97 μmol/g, respectively. Ultrasound treatment changed the physicochemical properties of β‐lactoglobulin including particle size (from 1.21 ± 0.05 nm to 1.66 ± 0.03 nm), absolute zeta potential (from 15.47 ± 1.60 mV to 27.63 ± 3.30 mV), and solubility (from 84.66% to 95.17%). Ultrasound treatment increased α‐helix and β‐sheet structures of β‐lactoglobulin. Intrinsic fluorescence intensity of ultrasound‐treated β‐lactoglobulin was increased with shift of λmax from 334 to 329 nm. UV absorption of β‐lactoglobulin was decreased with shift of λmax from 288 to 285 nm after ultrasound treatment. There were no significant changes in high‐performance liquid chromatography and protein electrophoretic patterns. These findings indicated that ultrasound treatment had high potential in modifying the physiochemical and structural properties of β‐lactoglobulin for industrial applications