Improving oxidative stability of echium oil emulsions fabricated by Microfluidics: Effect of ionic gelation and phenolic compounds

Microfluidics potential for developing food-grade microstructures through emulsification processes and their application

The food sector continues to face challenges in developing techniques to increase the bioavailability of bioactive chemicals. Utilising microstructures capable of encapsulating diverse compounds has been proposed as a technological solution for their transport both in food and into the gastrointestinal tract. The present review discusses the primary elements that influence the emulsification process in microfluidic systems to form different microstructures for food applications. In microfluidic systems, reactions occur within small reaction channels (1-1000 μm), using small amounts of samples and reactants, ca. 102-103 times less than conventional assays. This geometry provides several advantages for emulsion and encapsulating structure production, like less waste generation, lower cost and gentle assays. Also, from a food application perspective, it allows the decrease in particle dispersion, resulting in a highly repeatable and efficient synthesis method that also improves the palatability of the food products into which the encapsulates are incorporated. However, it also entails some particular requirements. It is important to obtain a low Reynolds number (Re < approx. 250) for greater precision in droplet formation. Also, microfluidics requires fluid viscosity typically between 0.3 and 1400 mPa s at 20 °C. So, it is a challenge to find food-grade fluids that can operate at the micro-scale of these systems. Microfluidic systems can be used to synthesise different food-grade microstructures: microemulsions, solid lipid microparticles, microgels, or self-assembled structures like liposomes, niosomes, or polymersomes. Besides, microfluidics is particularly useful for accurately encapsulating bacterial cells to control their delivery and release on the action site. However, despite the significant advancement in these systems' development over the past several years, developing and implementing these systems on an industrial scale remains challenging for the food industry.

Determination of the Optimum Conditions for Emulsification and Encapsulation of Echium Oil by Response Surface Methodology

Echium oil (EO) contains substantial amounts of omega-3 fatty acids, which are important because of their benefits to human health. However, they are prone to oxidation. The aim of this study was to obtain the optimum conditions of microencapsulation of EO using spray drying by applying the response surface methodology (RSM). Central composite circumscribed design (CCC) was employed with a ratio of maltodextrin (MD):EmCap modified starch (MS) (80-90%, w/w), oil concentration (15-25%, w/w), and homogenization speed (5-15 × 103 rpm) as independent variables affecting droplet size (μm) and viscosity (Pa·s), which were chosen as responses for the emulsification process. The results revealed that the emulsion conditions containing MD:MS (89.7%:10.3%, w/w), oil concentration of (16.0%), and homogenization speed at (14.8 × 103 rpm) were found to be the optimum conditions. Furthermore, for encapsulation, CCC was employed with inlet temperature of 140-180 °C, air flow of 20-30%, and pump rates of 15-25% as independent variables. Total yield (%) and encapsulation efficiency (%) were chosen as responses for the encapsulation process. On the other hand, optimum conditions for encapsulation were as follows: inlet temperature of 140 °C, airflow rate of (30%) 0.439 m3/h, pump rate of (15%) 4.5 mL/min with respect to selected responses.

Exploration of the chemical constituents and its antioxidant, antibacterial activities of endophytic fungi isolated from the medicinal plant Dillenia indica

Assam, India being the pool for ethnomedicinal plants harbors diverse endophytic fungi constituting major bioactive metabolites. The present study was designed to screen the antioxidant, antibacterial activities along with the chemical constituents of the endophytic fungi isolated from the fruits of Dillenia indica (commonly known as Otenga in Assam). Screening of such metabolic compounds and their antioxidant, antibacterial activities can have tremendous potential in suppressing certain diseases. Agar well diffusion method has been used to carry out the antibacterial assay against three pathogenic bacteria two gram positive [Bacillus subtilis (MTCC No. 441); Staphylococcus aureus (MTCC No. 740)] and one gram negative [Escherichia coli (MTCC No. 739)]. Aspergillus fumigatus of ethyl acetate extract showed a prominent activity against Staphylococcus aureus followed by Aspergillus flavus and Aspergillus niger. Antioxidants have the potential to neutralize and inhibit the action of free radicals. The highest scavenging activity was exhibited by ethyl acetate extract of Aspergillus fumigatus in DPPH assay. Furthermore, the phytochemical screening revealed the presence of flavonoids, alkaloids, terpenoids and saponins. Result showed that ethyl acetate extract of Aspergillus fumigatus showed the highest phenolic content (236.81 ± 0.2 mg.g^-1) and least was shown by Aspergillus flavus (92.12 ± 1.4 mg.g^-1). Total flavonoids content for Aspergillus fumigatus (39.08 ± 0.2 mg.g^-1) was found to be highest compared to other isolates. Molecular identification of the endophytic fungus showing highest activity was done based on 18S rRNA. The sequenced was submitted in Genbank with accession number MH540721 showing high similarities with Aspergillus fumigatus strain 3,162,954. A. fumigatus strain is subjected to GC/MS analysis that revealed the chemical constituents 2-isopropyl-5-methyl-1-heptanol, dodecane, 1-fluoro-pentanoic acid, 2-ethylhexyl ester, 1-octanol, 2-butyl-1-dodecanol. Thus, the present work reveals that endophytic fungi colonizing in ethnomedicinal plant Dillenia indica could be a promising source for antioxidant and antibacterial activity. Further work is needed to add value in various therapeutic and pharmaceutical fields.

Inhibition of Escherichia coli ATP synthase and cell growth by dietary pomegranate phenolics

Historically, people have been using pomegranate to alleviate many disease conditions. Pomegranate is known for its antiinflammatory, antioxidant, neuroprotective, anticancer, and antibacterial properties. In the current study, we examined effects of 8 dietary phenolics present in pomegranate (DPPs)-cyanidin-3-glucoside, cyanin chloride, delphinidin-3-glucoside, delphinidin-3,5-diglucoside, pelargonidin-3-glucoside, pelargonin chloride, punicalagin, and punicalin-on Escherichia coli ATP synthase and cell growth. DPPs caused complete or near complete (89%-100%) inhibition of wild-type E. coli ATP synthase and partial (5%-64%) inhibition of mutant enzymes αR283D, αE284R, βV265Q, and γT273A. Growth inhibition of wild-type, null, and mutant strains in the presence of DPPs were lower than that of isolated wild-type and mutant ATP synthase. On a molar scale, cyanin chloride was the most potent, and pelargonidin-3-glucoside was the least effective inhibitor of wild-type ATP synthase. Partial inhibition of mutant enzymes confirmed that αR283D, αE284R, βV265Q, and γT273A are essential in the formation of the phytochemical binding site. Our results establish that DPPs are potent inhibitors of wild-type E. coli ATP synthase and that the antimicrobial nature of DPPs can be associated with the binding and inhibition of microbial ATP synthase. Additionally, selective inhibition of microbial ATP synthase by DPPs is a useful method to combat antimicrobial resistance.

Review on the Regulation of Plant Polyphenols on the Stability of Polyunsaturated-Fatty-Acid-Enriched Emulsions: Partitioning Kinetic and Interfacial Engineering

The plant polyphenols are normally presented as natural functional antioxidants, which also possess the potential ability to improve the physicochemical stability of polyunsaturated fatty acid (PUFA)-enriched emulsions by interface engineering. This review discussed the potential effects of polyphenols on the stability of PUFA-enriched emulsions from the perspective of the molecular thermodynamic antioxidative analysis, the kinetic of interfacial partitioning, and the covalent and non-covalent interactions with emulsifiers. Recently, research studies have proven that the interfacial structure of emulsions can be concurrently optimized via promoting interfacial partitioning of polyphenols and further increasing interfacial thickness and strength. Moreover, the applied limitations of polyphenols in PUFA-enriched emulsions were summarized, and then some valuable and constructive viewpoints were put forward in this review to provide guidance for the use of polyphenols in constructing PUFA-enriched emulsions.

Effects of antioxidants, proteins, and their combination on emulsion oxidation

Lipid oxidation largely determines the quality of emulsion systems as well as their final products. Therefore, an increasing number of studies have focused on the control of lipid oxidation, particularly on its mechanism. In this review, we discuss the factors affecting the efficiency of antioxidants in emulsion systems, such as the free radical scavenging ability, specifically emphasizing on the interfacial behavior and the influence of surfactants on the interfacial distribution of antioxidants. To enhance the antioxidant efficiency of antioxidants in emulsion systems, we discussed whether the combination of antioxidants and proteins can improve antioxidant effects. The types, mixing applications, structures, interface behaviors, effects of surfactants on interfacial proteins, and the location of proteins are associated with the antioxidant effects of proteins in emulsion systems. Antioxidants and proteins can be combined in both covalent and non-covalent ways. The fabrication conditions, conjugation methods, interface behaviors, and characterization methods of these two combinations are also discussed. Our review provides useful information to guide better strategies for providing stability and controlling lipid oxidation in emulsions. The main challenges and future trends in controlling lipid oxidation in complex emulsion systems are also discussed.

Enhancement of physicochemical and encapsulation stability of O1/W/O2 multiple nanoemulsions loaded with coenzyme Q10 or conjugated linoleic acid by incorporating polyphenolic extract

Multiple O1/W/O2 nanoemulsions and O1/W nanoemulsions fortified with CLA or CoQ10 were produced using extra virgin olive or olive pomace oil and were also incorporated with polyphenols extracted from olive kernel to enhance their kinetic and chemical stability. They were prepared using a high-speed ultrasonic homogenizer. Specifically, nanoemulsions with 6 wt% lipid phase and 6 wt% non-ionic emulsifier (Tween 40) were produced and they demonstrated a droplet diameter >200 nm and high encapsulation stability during 30 days of storage at 4 °C or 25 °C. The incorporation of CLA or CoQ10 and polyphenolic compounds facilitated the homogenization of emulsions, reducing the droplet size and enhancing their chemical stability, and their bioactive retention values were >79%. O1/W/O2 nanoemulsions were produced using a mixture of non-ionic emulsifiers (Span 20 and Tween 40) and the O1/W enriched nanoemulsion as the dispersed phase. All multiple emulsions showed a bimodal droplet size distribution and Newtonian behavior while polyphenols facilitated their homogenization. Both vegetable oils resulted in samples with high kinetic and chemical stability; the bioactive retention values were found to be >80% at the end of 30 days of storage at 4 °C or 25 °C. Extra virgin olive oil resulted in more stable nanoemulsions in regards to kinetic and chemical stability at 4 °C, showing limited creaming and sedimentation boundary. Multiple nanoemulsions with the lowest initial droplet size presented the lowest droplet diameter growth and phase separation and the highest retention values. By comparing O1/W nanoemulsions and O1/W/O2 nanoemulsions, we noted that the reduction in the total phenolic content and antioxidant activity during storage was higher in the O1/W type. However, both delivery systems protected CLA and CoQ10 presenting high retention during storage. FTIR spectra before and after ultrasonic homogenization indicated that the sonication process did not significantly affect the lipid phase of O1/W/O2 nanoemulsions.

Extracts of endophytic fungi from leaves of selected Nigerian ethnomedicinal plants exhibited antioxidant activity

Background

Plants with an ethnobotanical history are known to harbor diverse group of endophytic fungi, which constitute major natural sources of bioactive compounds. In the present study, we evaluated the antioxidant activity of endophytic fungi from eight Nigerian ethnomedicinal plants. Endophytic fungi were isolated from the leaves of Acalypha ornata, Albizia zygia, Alchornea cordifolia, Chrysophyllum albidum, Ficus exasperata, Gomphrena celosioides, Millettia thonningii, and Newbouldia laevis.

Methods

Endophytic fungi were isolated from the leaves of selected plants via surface sterilization. Isolated fungi were identified by internal transcribed spacer (ITS-rDNA) sequence analysis. Pure fungal strains were subjected to fermentation process on solid rice medium and metabolites extracted using ethyl-acetate. Fungal crude extracts were screened for antioxidant activity using 2, 2- diphenyl-1-picrylhydrazyl (DPPH) radical scavenging and reduction of ferric ion assays. Gas chromatography/mass spectrometry (GC/MS) analysis was used to identify the major chemical constituents in active fungal extracts.

Results

A total of eighteen fungal endophytes with fungal codes CU (061 and 062); ZA (161, 162, 163, and 164); LO (261); CA (041, 042, and 043); FE (081, 082, and 084); GE (091); MO (211 and 212); and NA (021 and 022) were isolated from the eight ethnomedicinal plants A. ornata, A. zygia, A. cordifolia, C. albidum, F. exasperata, G. celosioides, M. thonningii, and N. laevis respectively. ZA 163 and MO 211 fungal extracts showed significant (p < 0.05) radical scavenging activity with IC₅₀ values of 50.53 ± 0.01 and 86.69 ± 0.02 μg/ml respectively. Fungal extract CA 041 demonstrated significantly (p < 0.01) higher iron chelating activity than standard gallic acid with absorbance values of 0.803 and 1.107 at 250 and 500 μg/ml concentrations respectively. Pyrogallol, phenol, 2,6-dimethoxy-, phytol, dl-alpha-tocopherol, alpha-tocospiro, oleamide, methyl stearate, oleic acid, palmitic acid, campesterol, stigmasterol, β-sitosterol, urs-12-en-24-oic acid, 3-oxo-, methyl ester, lup-20(29)-en-3-one, and lupeol were detected in the selected active extracts.

Conclusion

These results showed that leaves of the selected Nigerian plants harbor diverse group of endophytic fungi, which can be potential antioxidant resource.

Graphical abstract

Microfluidic Assembly: An Innovative Tool for the Encapsulation, Protection, and Controlled Release of Nutraceuticals

Nutraceuticals have been gradually accepted as food ingredients that can offer health benefits and provide protection against several diseases. It is widely accepted due to potential nutritional benefits, safety, and therapeutic effects. Most nutraceuticals are vulnerable to the changes in the external environment, which leads to poor physical and chemical stability and absorption. Several researchers have designed various encapsulation technologies to promote the use of nutraceuticals. Microfluidic technology is an emerging approach which can be used for nutraceutical delivery with precise control. The delivery systems using microfluidic technology have obtained much interest in recent years. In this review article, we have summarized the recently introduced nutraceutical delivery platforms including emulsions, liposomes, microspheres, microgels, and polymer nanoparticles based on microfluidic techniques. Emphasis has been made to discuss the advantages, preparations, characterizations, and applications of nutraceutical delivery systems. Finally, the challenges, several up-scaling methods, and future expectations are discussed.

Effect of sesamol on the physical and chemical stability of plant-based flaxseed oil-in-water emulsions stabilized by proteins or phospholipids

Plant-based polyphenols are increasingly being explored as functional ingredients in emulsified food systems. In this study, the effects of sesamol on the physical and chemical stability of flaxseed oil-in-water emulsions stabilized by either phospholipids (sunflower) or proteins (whey or pea) were investigated. In the absence of sesamol, the protein-based emulsions displayed better physical stability than the phospholipid-based ones, which was related to their smaller particle diameter and higher particle charge. For the phospholipid-based emulsions, sesamol addition did not improve their physical stability, but it did inhibit lipid oxidation. In particular, it decreased the formation of secondary oxidation products, with a 65% reduction in TBAR formation compared to the control after 8 days of storage. For the protein-based emulsions, sesamol addition reduced particle aggregation and inhibited lipid oxidation, reducing the secondary oxidation products by around 85% after 19 days of storage. The inhibitory efficiency of sesamol in the pea protein-based emulsions was comparable to that in the whey protein-based ones. The effects of sesamol on the physical and chemical stability of the emulsions were related to its partitioning between the oil, water, and interfacial layers. This study suggests that adding sesamol to plant-based emulsions may improve their physical and chemical stability, thereby extending their shelf life.

Rapid quantitative detection of chloramphenicol in milk by microfluidic immunoassay

Chloramphenicol (CAP) is a toxic substance for human health, and detection of CAP residues in milk is necessary. However, most of the traditional CAP detection methods including high performance liquid chromatography-tandem mass spectrometry (HPLC-MS) and enzyme-linked immunosorbent assay (ELISA) are time-consuming and complicated. Herein, an automated microfluidics system for CAP detection in milk was developed. The residual CAP of multiple milk samples was quantitatively detected via competitive immunoassay in a single microfluidic chip simultaneously and automatically, and the reliability of the method was confirmed by flow cytometry. Completion of the detection by the system required less than 20 min and the cost for the detection of ten samples was about US$2.5. The limit of detection was 0.05 µg L^-1, and the recovery rate of CAP in milk ranged from 91.3% to 105.5%. The microfluidic system developed in this study exhibited considerable potential in the point-of-care testing (POCT) of CAP in milk.

Encapsulation of wheat germ oil in alginate-gelatinized corn starch beads: Physicochemical properties and tocopherols' stability

Microencapsulation by production of polymer beads from ionic gelation is a useful method to improve the stability of nutritional compounds. Wheat germ oil is a nutritional source of unsaturated fatty acids and phytonutrients, such as tocopherols (α and β), phytosterols, carotenoids, and phenolic compounds. This work studied the development of alginate-starch beads over the stability of encapsulated wheat germ oil. The beads contained sodium alginate and gelatinized corn starch in proportions of 2:0, 1:1, 1:2, and 1:4. The addition of small amounts (1:1) of gelatinized starch in the alginate emulsions improved the physicochemical properties and stability during storage. The emulsions had oil droplets with mean sizes ranging from 4.5 to 12.2 µm. The 1:1 samples showed more disperse oil droplets, explained by the molecular interaction between the starch chains and oil. The encapsulation efficiency was higher than 91%, and the beads' mean diameters were between 383.22 and 797.45 µm. The proportion of 1:1 alginate-starch also enhanced the beads' microstructures, avoiding oil oxidation. Six days accelerated stability (65 °C) evidenced higher tocopherols amounts (0.66 mg/g oil) and a lower oxidation (2.52 meq.O₂ /kg oil) for the 1:1 samples compared to the remained samples. PRACTICAL APPLICATION: Alginate-gelatinized corn starch beads loaded with wheat germ oil can be used as an ingredient in functional food products for the enrichment of nutrients. The use of starch decreased the oil oxidation and the loss of tocopherols during storage, indicating that the quality of the wheat germ oil will be desirable for longer durations of food storage.

β-Sitosterol Loaded Nanostructured Lipid Carrier: Physical and Oxidative Stability, In Vitro Simulated Digestion and Hypocholesterolemic Activity

The objective of the present study was to explore the potential of nanostructured lipid carriers (NLCs) for improving the oral delivery of β-sitosterol, a poorly water-soluble bioactive component with hypocholesterolemic activity. Two β-sitosterol formulations with different solid lipid compositions were prepared by melt emulsification, followed by the sonication technique, and the effect of storage conditions and simulated digestion on the physical, chemical and oxidative stability, bioaccessibility and release were extensively studied. Both NLC preparations remained relatively stable during the four weeks of storage at different conditions (4, 25 and 40 °C), with more superior stability at lower temperatures. The in vitro digestion experiment indicated a high physical stability after exposure to the simulated mouth and stomach stages and an improved overall β-sitosterol bioaccessibility at the end of the digestion. The NLCs presented an increased solubility and gradual release which could be justified by the remarkable affinity of β-sitosterol to the complex lipid mixture. An in vivo study demonstrated an improved reduction in the total cholesterol and low-density lipoprotein cholesterol plasma levels in mice compared with the drug suspension. These investigations evidenced the potential of the developed NLC formulations for the enhancement of solubility and in vivo performance of β-sitosterol.

Reducing carotenoid loss during storage by co-encapsulation of pequi and buriti oils in oil-in-water emulsions followed by freeze-drying: Use of heated and unheated whey protein isolates as emulsifiers

Buriti and pequi oils are rich in carotenoids and beneficial to human health; however, carotenoid oxidation during storage causes color loss in foods, making it difficult to use these oils in food products. This research aimed to encapsulate pequi oil and co-encapsulate pequi and buriti oils by emulsification using whey protein isolate (WPI) as an emulsifier in two forms, natural (unheated) and heated, followed by freeze-drying. The emulsions were studied by droplet size under different stress conditions, instability index, and rheology. The freeze-dried (FD) samples were studied after accelerated oxidation and the total carotenoid retention was determined; for the reconstituted FD, the zeta potential and droplet size were recorded after storage at 37 °C for 30 days. The emulsions were stable in all conditions, with average droplet sizes between 0.88 ± 0.03 and 2.33 ± 0.02 μm, and formulations with heated WPI presented the lowest instability index values. The FD's zeta potential values ranged from -50 ± 3 to -32 ± 3 mV. The co-encapsulated oils presented higher carotenoid retention (50 ± 1 and 48 ± 1%) than the free oils (31 ± 2%) after 30 days. The oxidative stability indexes were 51 ± 4 and 46 ± 3 for the co-encapsulated oils with unheated and heated WPI, respectively, and 20.5 ± 0.1 h for the free oils. FD formulations with 1:3 ratio of oil: aqueous phase and heated or unheated WPI showed the best carotenoid retention and oxidative stability, indicating that FD oil emulsions have potential as next-generation bioactive compound carriers.

Manipulating and studying triglyceride droplets in microfluidic devices

Triglyceride is the main lipid class in nature, found as droplets in both living systems and man-made products (such as manufactured foods and drugs). Characterizing triglyceride droplets in situ in these systems is complex due to many environmental interactions. To answer basic research questions about droplet formation, structuration, stability, or degradation, microfluidic strategies were developed, allowing well-controlled droplets to be formed, manipulated, and studied. In this review, these strategies are described, starting with the presentation of droplet production devices, with applications essentially related to microencapsulation and delivery, then detailing methods to monitor droplet degradation in situ and in real time, finishing with microfluidic platforms allowing the investigation of many aspects of biological lipid droplets simultaneously.

l-Histidine Crystals as Efficient Vehicles to Deliver Hydrophobic Molecules

l-Histidine (l-His) molecules can form highly ordered fluorescent crystals with tunable size and geometry. The polymorph A crystal of l-His contains hydrophobic domains within the structure's interior. Here, we demonstrate that these hydrophobic domains can serve as vehicles for highly efficient entrapment and transport of hydrophobic small molecules. This strategy shows the ability of l-His crystals to mask the hydrophobicity of various small molecules, helping to address issues related to their poor solubility and low bioavailability. Furthermore, we demonstrate that we can modify the surface of these crystals to define their function, suggesting the significance of l-His crystals in designing site-specific and bioresponsive platforms. As a demonstration, we use l-His crystals with loaded doxorubicin, featuring hyaluronic acid covalently bonded on the crystal surface, controlling its release in response to hyaluronidase. This strategy for entrapment of hydrophobic small molecules suggests the potential of l-His crystals for targeted drug-delivery applications.

Multiple Emulsions with Extracts of Cactus Pear Added in A Yogurt: Antioxidant Activity, In Vitro Simulated Digestion and Shelf Life

Consumers demand so-called natural in which additive and antioxidant preservatives are from natural origin. Research focuses in using extracts from plants and fruits that are rich in bioactive compounds such as phenolics and betalains, but these are also prone to interact with proteins and are exposed to suffer degradation during storage. In this work, we developed a fortified yogurt with the addition of betalains and polyphenols from cactus pear extract encapsulated in a multiple emulsion (ME) (W1/O/W2). Different formulations of ME were made with two polymers, gum arabic (GA) and maltodextrin (MD) and with the best formulation of ME four types of yogurt were prepared using different % (w/w) of ME (0%, 10%, 20% and 30%). Bioactive compounds, antioxidant activity, color and lactic acid bacteria (LAB) were analyzed in the different yogurts over 36 days of shelf life. Furthermore, in vitro simulated digestion was evaluated. The yogurts had significant (p < 0.05) differences and the ME protected the bioactive compounds, activity of antioxidants and color. The ME did not affect the viability of LAB during 36 days of storage. The in vitro digestion showed the best bioaccessibilities of antioxidant compounds with the yogurts with ME.

Effect of flaxseed polyphenols on physical stability and oxidative stability of flaxseed oil-in-water nanoemulsions

Recent studies have shown that the high susceptibility of flaxseed oil nanoemulsions to lipid oxidation limits their incorporation into functional foods and beverages. For this reason, the impact of various flaxseed phenolic extracts on the physical and oxidative stability of flaxseed oil nanoemulsions was investigated. Flaxseed lignan extract (FLE) and secoisolariciresinol (SECO) exhibited antioxidant activity whereas secoisolariciresinol diglucoside (SDG) and p-coumaric acid (CouA) exhibited prooxidant activity in the flaxseed oil nanoemulsions. The antioxidant potential of flaxseed phenolics in the nanoemulsions was as follows: SECO < CouA < SDG ≈ FLE. Moreover, the antioxidant/prooxidant activity of the phenolics was also related to their free radical scavenging activity and partitioning in the nanoemulsions. Our results suggested that both SECO and FLE were good plant-based antioxidants for improving the stability of flaxseed oil nanoemulsions.

Echium oil with oxidative stability increased by emulsion preparation in the presence of the phenolic compound sinapic acid followed by dehydration by spray and freeze drying processes

Echium oil is rich in omega-3, however, is unstable. The objective of this work was the co-encapsulation of echium oil and sinapic acid (SA) by emulsification using Arabic gum as emulsifier/carrier, followed by spray or freeze-drying. Eight treatments (S0, S200, S600 and S1000: particles spray dried with different concentrations of SA; L0, L200, L600 and L1000: particles freeze dried with different concentrations of SA) were analyzed in relation to microscopy, water activity (Aw), hygroscopicity, moisture, solubility, particle size, X-ray diffraction, thermogravimetry and accelerated oxidation. Particles of rounded shape and undefined form were obtained by spray and freeze-drying, besides ideal physicochemical properties for application (values from 0.091 to 0.365, 3.22 to 4.89%, 57 to 68% and 2.32 to 12.42 µm for Aw, moisture, solubility and particle size, respectively). All treatments protected the oil against oxidation, obtaining induction time of 5.31 h for oil and from 7.88 to 12.94 h for treatments. The better protection to oil was obtained with it emulsified and freeze-dried (L600); the encapsulation increased oxidative stability of the oil, besides facilitating its application over the fact the material is in powder form.

Thermal aging of edible oils: spectrophotometric study

The aim of the present study was to determine the spectrophotometric and thermal aging properties of various edible oils (olive, peanut, rapeseed, soybean and sunflower oils) which are commonly available in the Czech market. The samples were measured by UV/VIS absorption spectrometry and fluorescence spectroscopy. Detected substances of UV/VIS spectra were compared to expected oil composition; the highest absorbance values were detected in a wavelength range 300-550 nm which can be related to the presence of unsaturated fatty acids. The mixtures of oils were characterized by fluorescence spectroscopy; the individual oils were successfully distinguished according to their excitation-emission profiles. This method was also used to detect the samples of adulterated oils, i.e., the adulteration of high-quality oils with soybean oil. From a physicochemical point of view, the influence of temperature on the compounds of extra virgin olive oil was examined by thermal stress simulation. This thermal aging analysis demonstrated that the amount of oxidation products in olive oil increased during the heating whereas the chlorophyll content decreased. The results showed the ability of the techniques used, UV/VIS absorption spectrometry and fluorescence spectroscopy, to characterize the quality and composition of oils, and to distinguish individual oils in blends. UV/VIS spectrometry was also successfully employed for the evaluation of olive oil qualitative parameters according to the standard quality parameters by the "International Olive Council" (EEC 702/2007).

Controlling the Release from Enzyme-Responsive Microcapsules with a Smart Natural Shell

We design a natural and simple core-shell-structured microcapsule, which releases its cargo only when exposed to lipase. The cargo is entrapped inside a gel matrix, which is surrounded by a double-layer shell containing an inner solid lipid layer and an outer polymer layer. This outer polymer layer can be designed according to the intended biological system and is responsible for protecting the microcapsule architecture and transporting the cargo to the desired site of action. The lipid layer contains natural ester bonds, which are digested by lipase, controlling the release of cargo from the microcapsule core. To demonstrate the feasibility of this approach, our model system includes a colorant bixin entrapped inside a κ-carrageenan gel matrix. This core is surrounded by an inner beeswax-palmitic acid layer and an outer casein-poloxamer 338 layer. These fabricated microcapsules are then applied into Cheddar cheese, where they selectively color the cheese matrix.

Enhancing the physicochemical stability of β-carotene solid lipid nanoparticle (SLNP) using whey protein isolate

β-Carotene is a nutraceutical that acts as a coloring agent and as pro-vitamin A, but its incorporation into foods is limited because of its hydrophobicity and low chemical stability. The aim of this study was to improve the physicochemical stability of β-carotene by encapsulating into solid lipid nanoparticles (SLNPs) containing palmitic acid and corn oil, stabilized using whey protein isolate (WPI). The palmitic acid crystals covered the surface of the oil droplets and formed a solid shell to protect the encapsulated β-carotene. Corn oil decreased the exclusion of β-carotene from the solid lipid matrix to the surface of SLNPs. WPI increased the colloidal stability of the system, and improved β-carotene oxidative stability. The rate of color fading due to β-carotene degradation increased with increasing temperature and was faster at lower pH. Lower ionic strengths had a slight impact on β-carotene degradation, while higher ionic strengths accelerated β-carotene breakdown.

Antioxidant and Antiradical Properties of Selected Flavonoids and Phenolic Compounds

Phenolic compounds and flavonoids are known by their antioxidant properties and one of the most important sources for humans is the diet. Due to the harmful effects of synthetic antioxidants such as BHA and BHT, natural novel antioxidants have become the focus of attention for protecting foods and beverages and reducing oxidative stress in vivo. In the current study, we investigated the total antioxidant, metal chelating, Fe³⁺ and Cu²⁺ reduction, and free radical scavenging activities of some phenolic and flavonoid compounds including malvin, oenin, ID-8, silychristin, callistephin, pelargonin, 3,4-dihydroxy-5-methoxybenzoic acid, 2,4,6-trihydroxybenzaldehyde, and arachidonoyl dopamine. The antioxidant properties of these compounds at different concentrations (10–30 μg/mL) were compared with those of reference antioxidants such as BHA, BHT, α-tocopherol, and trolox. Each substance showed dose-dependent antioxidant activity. Furthermore, oenin, malvin, arachidonoyl dopamine, callistephin, silychristin, and 3,4-dihydroxy-5-methoxybenzoic acid exhibited more effective antioxidant activity than that observed for the reference antioxidants. These results suggest that these novel compounds may function to protect foods and medicines and to reduce oxidative stress in vivo.