Influence of particle size and ionic strength on the freeze-thaw stability of emulsions stabilized by whey protein isolate

The influence of particle size and ionic strength on the freeze-thaw(FT) stability of emulsions stabilized by whey protein isolate(WPI) was investigated in this study. The destabilization of emulsions during the FT process could be suppressed in a way by decreasing the particle size of the initial emulsions, which was the result of retarding the coalescence between oil droplets. To further improve the FT stability of emulsions, different amounts of Na Cl were added before emulsification. The emulsions with the ionic strength at 30–50 mmol/L exhibited good FT stability. Notably, the ionic strength in this range would not lower the freezing point of emulsions below the freezing temperature used in this study. Salt addition could improve the structural properties of proteins, which was available to strengthen the rigidity and thickness of interfacial layers, sequentially building up the resistance that the destruction of ice crystals to emulsions. Moreover, stronger flocculation between emulsion droplets could promote the formation of a gel-like network structure dominated by elasticity in the emulsion system, which might effectively inhibit the movement of droplets, and improve the FT stability of emulsions eventually. The result was of great significance for the preparation of emulsion-based foods with improved FT stability.

Gastrointestinal digestive fate of whey protein isolate coated liposomes loading astaxanthin:Lipolysis,release,and bioaccessibility

Whey protein isolate coated astaxanthin-loaded liposomes were prepared in this work.The gastrointestinal digestive fate of whey protein isolate coated astaxanthin-loaded liposomes was evaluated in terms of particle size,size distribution,zeta potential,and morphology during in vitro digestion as a function of time.Analysis on the particle size and morphology of whey protein isolate coated astaxanthin-loaded liposomes showed that the majority of particles maintained spherical shape with a progressive increase of particle size after passage through the digestion.The zeta potential on whey protein isolate coated astaxanthin-loaded liposomes became highly negative after digestion.As compared in uncoated liposomes,the astaxanthin release in whey protein isolate coated liposomes was slower in simulated gastric fluid digestion,while was faster in simulated intestinal fluid digestion.Through in vitro digestion,the bioaccessibility of astaxanthin was improved significantly after whey protein isolate coating.It was also found that the whey protein isolate coating could protect liposomes against destruction and suppress the lateral mobility of pyrene,resulting in lower micropolarity and fluidity of liposomal membrane during the digestion.These findings may guide the potential application of whey protein isolate coated liposomes for improving the bioaccessibility and stability of astaxanthin in nutraceuticals and pharmaceutics.

Combination of microwave heating and transglutaminase cross-linking enhances the stability of limonene emulsion carried by whey protein isolate

In this study,we examined the effect of transglutaminase(TG)cross-linking time(0 h,2 h,4 h,8 h,and 12 h)on the stability of limonene emulsion loaded by microwave-heated WPI(MWPI).Size exclusion chromatography results showed that molecular weight of TG-treated MWPI and WPI was enhanced with the increase in TG cross-linking time(0–12 h).Microwave and TG cross-linking decreased particle size(7.55%)and increasedζ-potential(5.33%)and protein adsorption(4.58%)of WPI emulsion at TG cross-linking time of 12 h.CLSM results showed smaller droplet size of MWPI-TG emulsion and its uniform size.The obtained limonene emulsion loaded by MWPI-TG at 12 h showed the lowest creaming index and the strongest oxidative stability under aerobic conditions after 10th days of storage.Thus,the combination of microwave heating and TG cross-linking effectively enhanced the stability of limonene emulsion stabilized by WPI and facilitating the application of WPI in the fields of food,medicine,cosmetics,and other areas.

Physicochemical properties and antibacterial application of silver nanoparticles stabilized by whey protein isolate

Nano metal materials have been widely explored to be applied in medical,environmental,and material science.Among these nanoparticles,especially silver nanoparticles(AgNPs),have drawn increasing attention for antimicrobial applications.Most researchers are keen on the development of the biologically friendly capping reagents for the synthesis of AgNPs,instead of unfriendly organic polymers.In this study,the liquid chemical reduction method was used to synthesize AgNPs with edible whey protein isolate(WPI)as a capping reagent.These WPI-AgNPs had a broad size distribution(average diameter of 138.6 nm),and their dimensions could be readily controlled in the range of 22.5-149.6 nm by introducing different concentrations of chloride.Subsequently,it was confirmed that WPI-AgNPs were formed through two mechanisms,which were respectively reduced in situ(without the addition of NaCl)and ex situ(in presence of NaCl)to yield silver nanoparticles.The WPI-AgNPs synthesized in presence of 10 mM of NaCl as mediation reagent were stable at room temperature or 4℃ up to 3 months.Furthermore,the synthesized WPI-AgNPs had a good antibacterial activity toward pathogens including Gram-negative E.coli and Gram-positive S.aureus.The results shed light on method and capping reagent to stabilize silver nanoparticles,which highlighted the potential of WPI and chloride in metal nanoparticle synthesis.