Food microencapsulation of bioactive compounds: Rheological and thermal characterisation of non-conventional gelling system

Joint protection strategies for Saccharomyces boulardii: exogenous encapsulation and endogenous biofilm structure

Biofilms are heterogeneous structures composed of microorganisms and the surrounding extracellular polymeric substances (EPS) that protect the microbial cells from harsh environments. Saccharomyces boulardii is the first yeast classified as a probiotic strain with unique properties. However, tolerance of S. boulardii biofilms to harsh environments especially during production and in the gastrointestine remains unknown. In this study, S. boulardii cells were encapsulated in alginate microcapsules and subsequently cultured to form biofilms, and their survival and tolerance were evaluated. Microencapsulation provided S. boulardii a confined space that enhanced biofilm formation. The thick alginate shell and the mature biofilm improved the ability of S. boulardii to survive under harsh conditions. The exogenous encapsulation and the endogenous biofilm structure together enhanced the gastrointestinal tolerance and thermotolerance of S. boulardii. Besides, as the alginate shell became thinner with an increase in the subsequent culture duration, the EPS of S. boulardii biofilms exerted an important protective effect in resisting high temperatures. The encapsulated biofilm of S. boulardii after 24-h culture exhibited 60 × higher thermotolerance at 60 °C (10 min), while those after 6-h and 24-h culture showed 1000 × to 550,000 × higher thermotolerance at 120 °C (1 min) compared with the planktonic cells without encapsulation. The present study's findings suggest that a combination of encapsulation and biofilm mode efficiently enhanced gastrointestinal tolerance and thermotolerance of S. boulardii. KEY POINTS: • Encapsulated S. boulardii in biofilm mode showed enhanced tolerance. • Exogenous shell and endogenous biofilm provided dual protection to S. boulardii.

Spray-drying encapsulation of microwave-assisted extracted polyphenols from Moringa oleifera: Influence of tragacanth, locust bean, and carboxymethyl-cellulose formulations

In this work, polyphenols from Moringa oleifera (Mor) leaves were extracted by microwave-assisted extraction (MAE) and encapsulated by spray-drying (SD). Particularly, we explored the influence of tragacanth gum (TG), locust bean gum (LBG), and carboxymethyl-cellulose (CMC) as wall-materials on the physicochemical behavior of encapsulated Mor. Single or combined wall-material treatments (100:00 and 50:50 ratios, and total solid content 1%) were tested. The results showed the wall-material had a significant effect on the process yield (55.7-68.3%), encapsulation efficiency (24.28-35.74%), color (yellow or pale-yellow), total phenolic content (25.17-27.49 mg GAE g^-1 of particles), total flavonoid content (23.20-26.87 mg QE g^-1 of particles), antioxidant activity (DPPH^• = 5.96-6.95 mg GAE g^-1; ABTS^•+ = 5.61-6.18 mg TE g^-1 of particles), and particle size distribution (D₅₀ = 112-1946 nm) of the encapsulated Mor. On the other hand, SEM analysis showed smooth and spherical particles, while TGA and DSC analyses confirmed the encapsulation of bioactive compounds based on the changes in thermal peaks. Finally, XRD analysis showed that the particles have an amorphous behavior. The encapsulated Mor produced with individual TG or CMC demonstrated better properties than those obtained from mixed gums. Thus, TG or CMC might be feasible wall materials for manufacturing encapsulated Mor that conserve the phenolic content and antioxidant activity.

Synthesis of Starch Nanoparticles and Their Applications for Bioactive Compound Encapsulation

In recent years, starch nanoparticles (SNPs) have attracted growing attention due to their unique properties as a sustainable alternative to common nanomaterials since they are natural, renewable and biodegradable. SNPs can be obtained by the breakdown of starch granules through different techniques which include both physical and chemical methods. The final properties of the SNPs are strongly influenced by the synthesis method used as well as the operational conditions, where a controlled and monodispersed size is crucial for certain bioapplications. SNPs are considered to be a good vehicle to improve the controlled release of many bioactive compounds in different research fields due to their high biocompatibility, potential functionalization, and high surface/volume ratio. Their applications are frequently found in medicine, cosmetics, biotechnology, or the food industry, among others. Both the encapsulation properties as well as the releasing processes of the bioactive compounds are highly influenced by the size of the SNPs. In this review, a general description of the different types of SNPs (whole and hollow) synthesis methods is provided as well as on different techniques for encapsulating bioactive compounds, including direct and indirect methods, with application in several fields. Starches from different botanical sources and different bioactive compounds are compared with respect to the efficacy in vitro and in vivo. Applications and future research trends on SNPs synthesis have been included and discussed.

Encapsulation of two fermentation agents, Lactobacillus sakei and calcium ions in microspheres

Alginate microspheres loaded with two fermentation active agents, calcium cations and strain LS0296 identified as Lactobacillus sakei, have been prepared and characterized. The role of calcium cation is twofold, it acts as gelling cation and as fermentation active agent. Encapsulation and the presence of calcium ions in the same compartment do not inhibit the activity of LS0296. Molecular interactions in microspheres are complex, including mainly hydrogen bonds and electrostatic interactions. In vitro calcium cations and strain LS0296 release profiles were fitted to the Korsmeyer-Peppas empirical model. The calcium cation release process is driven at first by Fickian diffusion through microspheres and then by anomalous transport kinetics. The in vitro LS0296 release process is driven by Fickian diffusion through microspheres showing a much slower releasing rate than calcium cations. The release of LS0296 strain is followed by a decrease in the pH value. Results obtained give us a new insight into complex interactions between bacterial cultures and microsphere constituents. Prepared formulations of calcium alginate microspheres loaded with LS0296 could be used as a new promising tool and a model for different starter cultures encapsulation and use in the production of fermented foods.

Bioavailability, rheology, and sensory evaluation of mayonnaise fortified with vitamin D encapsulated in protein-based carriers

Vitamin D lost its functionality during processing and storage, thus, encapsulation with proteins is desirable to preserve bioactivity. The aim of the current study was to develop encapsulated vitamin D fortified mayonnaise (VDFM) using whey protein isolates (WPI) and soy protein isolates (SPI) as encapsulating materials in three different formulations, that is, 10% WPI, 10% SPI, and 5/5% WPI/SPI. Increased shear stress decreased the apparent viscosity along with significant effects on the loss modulus of VDFM. WPI encapsulates showed better results as compared to SPI. WPI based VDFM (M₁ ) depicted the best results in terms of size and dispersion uniformity of oil droplets. Hue angle and total change differed significantly among treatments. The highest value for overall acceptability was acquired by M₃ (5:5%WPI:SPI-encapsulates) thus proceed for in vivo trials. Serum vitamin D level was significantly higher in the encapsulated VDFM rat group (58.14 ± 6.29 nmol/L) than the control (37.80 ± 4.98 nmol/L). Conclusively, WPI and SPI encapsulates have the potential to improve the stability and bioavailability of vitamin D.

Antioxidant and antibacterial activities of omega-3 rich oils/curcumin nanoemulsions loaded in chitosan and alginate-based microbeads

Omega-3 fatty acids can be considered as potential alternative therapeutic agents because of their antimicrobial and antioxidant properties. Two investigated omega-3 rich oils (flaxseed or fish) have been nanoemulsified with and without the natural antioxidant (curcumin, Cur) followed by their incorporation into crosslinked polymeric microbeads. The microbeads were developed from chitosan (CS), alginate (AL) and their combination (CSAL). Results indicated that the mean droplet diameter of the plain and Cur-loaded nanoemulsions ranged from 62.3 to 111.29 nm. The microbeads produced from AL, CS and their combination without Cur had predominantly shriveled surfaces compared to Cur-loaded ones. Addition of Cur was found to enhance oxidative stability, encapsulation efficiency, loading capacity, and antioxidant activity of the formulated microbeads. Plain fish oil revealed more antibacterial activity than plain flaxseed oil. Fish oil nanoemulsion-in-AL microbeads had more antibacterial activity than nanoemulsions of flaxseed oil-in-AL, fish oil-in-CS and the combined (CSAL) microbeads. However, flaxseed oil nanoemulsion-in-CS microbeads showed higher antibacterial activity than nanoemulsions of fish oil-in-CS, flaxseed oil-in-AL and the combined microbeads. The obtained results suggested the suitability of the formulated nanoemulsions-loaded microbeads to be used in food and pharmaceuticals products.

3D printing of food: pretreatment and post-treatment of materials

BACKGROUND

Food 3 D printing is an emerging food processing technology. Due to the advantages of functionalization, customization, personalized nutrition design, simplified supply chain and broadening existing food materials, 3 D printing has been extensively studied in the food sector in the past decade. Many factors influence the accuracy and quality of food 3 D printing, which are also the challenges to researchers. Currently, most of the research focuses on the development of printable materials and control of printing parameters to improve the printing accuracy and product quality. However, the influence of material pretreatment methods and post-processing techniques on food 3 D printing have received less attention.

MAIN CONTENT

By collecting the available data and research, this paper analyzes the effect of pretreatment technologies (crushing, gelation, etc.) and post-treatment technologies (cooking, drying, fast cooling technology, 4 D printing, etc.) on the accuracy and shape fidelity of 3 D printed food products. It also summarizes the current challenges of food 3 D printing and proposes some thoughts on the future development of this technology.

Physicochemical and Microstructural Properties of Polymerized Whey Protein Encapsulated 3,3'-Diindolylmethane Nanoparticles

The fat-soluble antioxidant 3,3′-diindolylmethane (DIM), is a natural phytochemical found in Brassica vegetables, such as cabbage, broccoli, and Brussels sprouts. The stability of this compound is a major challenge for its applications. Polymerized whey protein (PWP)-based DIM nanoparticles were prepared at different mass ratios of protein and DIM by mixing PWP and DIM followed by ultrasound treatment for 4 min. All the nanoparticles were studied for particle size, zeta potential, rheological and microstructural properties, and storage stability. The mean particle size of the PWP-based nanoparticles was significantly increased (p < 0.05) by the addition of DIM at different mass ratios, ranging from 241.33 ± 14.82 to 270.57 ± 15.28 nm. Zeta potential values of all nanoparticles were highly negative (greater than ±30 mV), suggesting a stable solution due its electrostatic repulsive forces. All samples exhibited shear thinning behavior (n < 1), fitted with Sisko model (R² > 0.997). Fourier Transform Infrared (FTIR)spectra revealed that the secondary structure was changed and the absorption intensity for hydrogen bonding got stronger by further incorporating DIM into PWP. Transmission electronic microscopy (TEM) images showed spherical and smooth surface shape of the PWP-based nanoparticles. DIM encapsulated by PWP showed enhanced stability at 4, 37 and 55 °C for 15 days evidenced by changes in mean particle size and color (a*-value and b*-value) compared with control (DIM only). In conclusion, the polymerized whey protein based 3,3′-diindolylmethane nanoparticles are stable and the encapsulation may protect the core material from oxidation.

Preparation of acacia tannin loaded lipid microparticles by solid-in-oil-in-water and melt dispersion methods, their characterization and evaluation of their effect on ruminal gas production In Vitro

Tannin extracts have wide biological activity in ruminant nutrition. The possibility of masking their bitter taste and enhancing sustained release in the rumen can be achieved through encapsulation. The objectives of this study were to prepare an encapsulated Acacia tannin extract (ATE) suitable for ruminants using the solid-in-oil-in-water (S/O/W) method, and to evaluate the microparticles in terms of morphology, encapsulation efficiency and in vitro release under varying pH. Subsequently, the effect of the microparticles on rumen in vitro gas and methane production would be evaluated. Lipid microparticles were prepared using the double emulsion process with palm oil and lard, dichloromethane, and Tween80/Span80 emulsifiers. The microparticles produced by S/O/W emulsion tended to be smaller (P = 0.06), and had greater encapsulation efficiency compared with those produced by the melt dispersion method. Scanning electron micrographs showed microparticles had stable cylindrical and spherical shapes, with mean size of 34± 10.2 μm. Maximum encapsulation efficiencies of 78.6% and 80.1% were obtained with lard and palm oil as lipid wall materials, respectively, even under high core material loading percentage of 80%. Wall material type did not affect the characteristics of microparticles. In acetate buffer, only about 20% of tannin was released from the lipid-encapsulated microparticles into buffer media after 24 hours. In contrast, about 90% of the tannin had been released into solution before eight hours in the crude extract. Lipid-encapsulated ATE reduced rumen gas and methane production in vitro (P ˂0.05) in both Eragrostis and total mixed ration (TMR) diet substrates, but the magnitude of reduction was lower than that obtained when unencapsulated ATE was the additive (10% vs 20% for total gas and 17% vs 24% for methane). Crude ATE and palm oil encapsulated ATE reduced the concentration of methane in sampled gas (P = 0.054) when fermenting the TMR substrate, but this effect was not observed in the Eragrostis substrate. Ammonia nitrogen concentration was greater in encapsulated ATE compared with the crude ATE (P ˂0.001). These results show that the lipid-encapsulated ATE produced small-sized and more uniform microparticles, with high encapsulation efficiency compared with microparticles prepared by melt dispersion. Encapsulation of ATE enhanced the sustained release of tannin in the rumen, and with the potential to improve gas production and reduce methane production.

Biocheese: a food probiotic carrier

This review describes some aspects related to the technological barriers encountered in the development and stability of probiotic cheeses. Aspects concerning the viability of probiotic cultures in this matrix are discussed and the potential of cheese as a biofunctional food carrier is analyzed, outlying some points related to health and safety. In general, the manufacture of probiotic cheese should have little change when compared with the elaboration of cheese in the traditional way. The physicochemical and technological parameters influencing the quality of these products have also to be measured so as to obtain a process optimization.

Microencapsulation of bioactive principles with an airless spray-gun suitable for processing high viscous solutions

PURPOSE

to design, assemble and test a prototype of a novel production plant, suitable for producing microparticles (MPs) by processing highly viscous feed solutions (FSs).

METHODS

the prototype has been built using a commercial air compressor, a piston pump, an airless spray-gun, a customized air-treatment section, a timer, a rotating base, and a filtration section. Preliminary prototype parameter setting was carried out to individuate the best performing nozzle's dimension, the nebulization timing, and the CaCl2 concentration in the gelation fluid. In addition, prototype throughput (1 L to 5 L) and the range of practicable feed solution (FS) viscosities were assayed. A set of four batches was prepared in order to characterize the MPs, in terms of mean particle size and distribution, flow properties, swelling, encapsulation efficiency and release.

RESULTS

according to a qualitative scoring, the large nozzle was suitable to nebulize FSs at a higher alginate concentration. Conversely, the small nozzle performed better in the processing of FSs with an alginate concentration up to 2% w/v. Only at the highest degree of viscosity, corresponding to 5% w/v of alginate, the FS processing was not technically possible. Among the CaCl2 concentrations considered, 15% w/v was recognized as the most versatile. The prototype appears to be convenient and suitable to grant a high yield starting from 2 L of FS. The flow behavior of the FSs assayed can be satisfactorily described with the Carreau-Yasuda equation and the throughput begins to slightly decrease for FSs at alginate concentrations exceeding 3% w/v. MP morphology was irregular with crumpled shape. The angle of repose indicates a good flowability and the release studies showed gastro-resistance and potential prolonged release applications.

CONCLUSIONS

the novel prototype of production plant is suitable to process large amounts (2 L or more) of FSs, characterized by a high viscosity, to produce MPs suitable for bioactive principle delivery.

Development of microencapsulation delivery system for long-term preservation of probiotics as biotherapeutics agent

The administration of probiotic bacteria for health benefit has rapidly expanded in recent years, with a global market worth $32.6 billion predicted by 2014. The oral administration of most of the probiotics results in the lack of ability to survive in a high proportion of the harsh conditions of acidity and bile concentration commonly encountered in the gastrointestinal tract of humans. Providing probiotic living cells with a physical barrier against adverse environmental conditions is therefore an approach currently receiving considerable interest. Probiotic encapsulation technology has the potential to protect microorganisms and to deliver them into the gut. However, there are still many challenges to overcome with respect to the microencapsulation process and the conditions prevailing in the gut. This review focuses mainly on the methodological approach of probiotic encapsulation including biomaterials selection and choice of appropriate technology in detailed manner.

Microencapsulation of Lactobacillus helveticus and Lactobacillus delbrueckii using alginate and gellan gum

Sodium alginate (SA) at 2% (w/v) and low acylated gellan gum (LAG) at 0.2% (w/v) were used to microencapsulate Lactobacillus helveticus and Lactobacillus delbrueckii spp lactis by employing the internal ionic gelation technique through water-oil emulsions at three different stirring rates: 480, 800 and 1200 rpm. The flow behavior of the biopolymer dispersions, the activation energy of the emulsion, the microencapsulation efficiency, the size distribution, the microcapsules morphology and the effect of the stirring rate on the culture viability were analyzed. All of the dispersions exhibited a non-Newtonian shear-thinning flow behavior because the apparent viscosity decreased in value when the shear rate was increased. The activation energy was calculated using the Arrhenius-like equation; the value obtained for the emulsion was 32.59 kJ/mol. It was observed that at 400 rpm, the microencapsulation efficiency was 92.83%, whereas at 800 and 1200 rpm, the stirring rates reduced the efficiency to 15.83% and 4.56%, respectively, evidencing the sensitivity of the microorganisms to the shear rate (13.36 and 20.05 s(-1)). Both optical and scanning electron microscopy (SEM) showed spherical microcapsules with irregular topography due to the presence of holes on its surface. The obtained size distribution range was modified when the stirring rate was increased. At 400 rpm, bimodal behavior was observed in the range of 20-420 μm; at 800 and 1200 rpm, the behavior became unimodal and the range was from 20 to 200 μm and 20 to 160 μm, respectively.

Novel bio-active lipid nanocarriers for the stabilization and sustained release of sitosterol

In this work, new stable and efficiently bio-active lipid nanocarriers (NLCs) with antioxidant properties have been developed for the transport of active ingredients in food. The novel NLCs loaded with β-sitosterol/β-sitosterol and green tea extract (GTE) and prepared by a combination of natural oils (grape seed oil, fish oil and squalene) and biological lipids with food grade surfactants, were physico-chemically examined by DLS, TEM, electrokinetic potential, DSC and HPLC and found to have main diameters less than 200 nm, a spherical morphology, excellent physical stability, an imperfect crystalline lattice and high entrapment efficiency. The novel loaded-NLCs have demonstrated the potential to develop a high blocking action of chain reactions, trapping up to 92% of the free-oxygen radicals, as compared to the native β-sitosterol (AA%=36.5). Another advantage of this study is associated with the quality of bio-active NLCs based on grape seed oil and squalene to manifest a better sitosterol-sustained release behaviour as compared to their related nanoemulsions. By coupling both in vitro results, i.e. the enhanced antioxidant activity and superior release properties, this study emphasizes the sustainability of novel bio-active nanocarriers to gain specific bio-food features for development of functional foods with a high applicability spectrum.