Spray drying and rehydration of macadamia oil-in-water emulsions: Impact of macadamia protein isolate to chitosan hydrochloride ratio

Insights on tiger nut (Cyperus Esculentus L.) oil-loaded microcapsules: characterization and oxidation stability analysis

In this paper, tiger nut oil-loaded microcapsules (TNOMs) were prepared by complexation soybean protein isolate (SPI) and maltodextrin (MD) as wall materials using the spray drying method with tiger nut oil (TNO) as the core material, and its physicochemical properties and stabilities were characterized and analyzed. Under the optimum conditions, the encapsulation efficiency (EE) of TNOMs could reach up to 91.23%. Of note, after 60 days of storage at 60 °C, the peroxide value (PV) of TNO was almost 21.8 times as much as that of TNO encapsulated. Furthermore, TNOMs had good thermal stability below 200 °C and are sufficient for the general food processing needs. By fitting Arrhenius oxidation kinetics model, it was predicted that the shelf life of the product stored at 25 °C was 352.48 d. Therefore, it is promised to be applied to the development of high oleic acid food in the future. This study offered a theoretical framework for utilization and broadening the range of applications of TNO in the food industry.

Revealing the potential effects of oil phase on the stability and bioavailability of astaxanthin contained in Pickering emulsions: In vivo, in vitro and molecular dynamics simulation analysis

This study investigated the effects of oil phases on the encapsulation rate, storage stability, and bioavailability of astaxanthin (ASTA) in Pickering emulsions (PEs). Results showed PEs of mixed oils (olive oil/edible tea oil) had excellent encapsulation efficiency (about 96.0%) and storage stability of ASTA. In vitro simulated gastrointestinal digestion results showed the mixed oil PE with a smaller interfacial area and higher monounsaturated fatty acid content may play a better role in improving ASTA retention and bioaccessibility. In vivo absorption results confirmed the mixed oil PE with an olive oil/edible tea oil of 7:3 was more favorable for ASTA absorption. Molecular dynamics simulation showed ASTA bound more strongly and stably to fatty acid molecules in the system of olive oil/edible tea oil of 7:3; and van der Waals force was the main binding force. NMR further proved there really were interactions between ASTA and four main fatty acids.

Effect of dry- and moist-heat treatment processes on the structure, solubility, and in vitro digestion of macadamia protein isolate

This study aimed to enhance the solubility and digestibility of macadamia protein isolate (MPI) for potential utilization in the food industry. The impact of dry- and moist-heat treatments at various temperatures (80, 90, and 100°C) and durations (15 and 30 min) on macadamia protein's microstructure, solubility, molecular weight, secondary and tertiary structure, thermal stability, and digestibility were investigated and evaluated. The heating degree was found to cause roughening of the MPI surface. The solubility of MPI after dry-heat treatment for 15 min at 100°C reached 290.96 ± 2.80% relative to that of untreated protein. Following heat treatment, the bands of protein macromolecules disappeared, while MPI was stretched by vibrations of free and hydrogen-bonded hydroxyl groups. Additionally, an increase in thermal stability was observed. After heat treatment, hydrophobic groups inside the protein are exposed. Heat treatment significantly improved the in vitro digestibility of MPI, reaching twice that of untreated protein. The results also demonstrated that dry- and moist-heat treatments have distinct impacts on MPI, while heating temperature and duration affect the degree of modification. With a decreased ordered structure and increased random coil content, the dry-heat treatment significantly enhanced the in vitro digestibility of MPI. The digestibility of MPI after dry-heat treatment for 30 min at 90°C increased by 77.82 ± 2.80% compared to untreated protein. Consequently, compared to moist-heat treatment, dry-heat treatment was more effective in modifying macadamia protein. Dry-heat treatment of 30 min at 90°C was determined as the optimal condition. PRACTICAL APPLICATION: Heat treatment enhances MPI characteristics, potentially advancing macadamia-derived food production, including plant-based beverages and protein supplements.

Spray drying the Pickering emulsions stabilized by chitosan/ovalbumin polyelectrolyte complexes for the production of oxidation stable tuna oil microcapsules

The microencapsulation of polysaturated fatty acids by spray drying remains a challenge due to their susceptibility to oxidation. In this work, antioxidant Pickering emulsions were attempted as feeds to produce oxidation stable tuna oil microcapsules. The results indicated that the association between chitosan (CS) and ovalbumin (OVA) was a feasible way to fabricate antioxidant and wettable complexes and a high CS percentage favored these properties. The particles could yield tuna oil Pickering emulsions with enhanced oxidation stability through high-pressure homogenization, which were successfully spray dried to produce microcapsules with surface oil content of 8.84 % and microencapsulation efficiency of 76.65 %. The microcapsules exhibited significantly improved oxidation stability and their optimum peroxide values after storage at 50 °C, 85 % relative humidity, or natural light for 15 d were 48.67 %, 60.07 %, and 39.69 % respectively lower than the powder derived from the OVA-stabilized emulsion. Hence, Pickering emulsions stabilized by the CS/OVA polyelectrolyte complexes are potential in the production of oxidation stable polyunsaturated fatty acid microcapsules by spray drying.

Improved physicochemical properties and in vitro digestion of walnut oil microcapsules with soy protein isolate and highly oxidized konjac glucomannan as wall materials

This study investigated the effect of the oxidation degrees of oxidized konjac glucomannan (OKGM) on the encapsulation efficiency (EE), physicochemical and in vitro digestive properties of soy protein isolate (SPI)-based microcapsules walnut oil using experimental and computational approaches. Microcapsules had the highest EE when the ratio of OKGM and SPI to oil was 2.5:1. With increasing the oxidation degree of OKGM, the EE of microcapsules was increased and the hygroscopicity was decreased. Molecular dynamics simulation results showed that SPI/oil/highly OKGM had relatively low binding energy (-4.03 × 106 kJ/mol) and strong electrostatic interactions, which may contribute to a higher EE and lower hygroscopicity of microcapsules, respectively. The oxidative stability of the oil was markedly improved by SPI and OKGM, and microcapsules prepared with SPI and highly OKGM had the highest in vitro digestion. This study provided theoretical support for broadening the application of microcapsules prepared with SPI and OKGM.

Spray-drying and rehydration on β-carotene encapsulated Pickering emulsion with chitosan and seaweed polyphenol

The spray-drying process to generate microcapsules from Pickering emulsions needs high temperatures, leading to instability of emulsions and degradation of encapsulated thermosensitive compounds (β-carotene). However, these effects may be attenuated by the introduction of seaweed polyphenols into the emulsion interfacial layers, although the effects underlying this protective mechanism have not been explored. This study evaluates the effects of spray-drying/rehydration on the morphology, encapsulation efficiency, redispersibility, and stability of β-carotene loaded Pickering emulsions stabilized by chitosan (PESC) and Pickering emulsions stabilized by chitosan/seaweed polyphenols (PESCSP). The encapsulation efficiency of β-carotene in PESCSP microcapsules (61.13 %) was higher than PESC (53.91 %). Rehydrated PESCSP exhibited more regular droplet size distribution, higher stability, stronger 3D network morphology, and lower redispersibility index (1.5) compared to rehydrated PESC. Analyses of interfacial layers of emulsions revealed that chitosan covalently bound fatty acids at their hydrophobic side. Polyphenols were linked to chitosan at the hydrophilic side of emulsions through hydrogen bonds, providing 3D network between droplets and antioxidant activities to inhibit the degradation of β-carotene. This study emphasized the role of polyphenols in the interfacial layers of Pickering emulsions for the development of efficient delivery systems and protection of β-carotene and other thermosensitive bioactive compounds during spray-drying and rehydration.

Ingredients, structure and reconstitution properties of instant powder foods and the potential for healthy product development: a comprehensive review

Instant foods are widely presented in powder forms across different food segments, which potentially can be formulated with functional or beneficial compounds to provide health benefits. Many reconstituted instant powder foods form colloidal suspensions with complex structures. However, designing instant powder food could be challenging due to the structural complexity and high flexibility in formulation. This review proposed a new classification method for instant powder foods according to the solubility of ingredients and the structure of the reconstituted products. Instant powder foods containing insoluble ingredients are discussed. It summarised challenges and current advances in powder treatments, reconstitution improvement, and influences on food texture and structure to facilitate product design in related industries. The characteristics and incorporation of the main ingredients and ingredients with health benefits in product development were reviewed. Different products vary significantly in the ratios of macronutrients. The macronutrients have limited solubility in water. After being reconstituted by water, the insoluble components are dispersed and swell to form colloidal dispersions with complex structures and textures. Soluble components, which dissolve in the continuous phase, may facilitate the dispersing process or influence the solution environment. The structure of reconstituted products and destabilising factors are discussed. Both particle and molecular structuring strategies have been developed to improve wettability and prevent the formation of lumps and, therefore, to improve reconstitution properties. Various types of instant food have been developed based on healthy or functional ingredients and exhibit positive effects on the prevention of non-communicable diseases and overall health. Less processed materials and by-products are often chosen to enhance the contents of dietary fibre and phenolic compounds. The enrichment of phenolic compounds, dietary fibres and/or probiotics tend to be simultaneous in plant-based products. The process of the ingredients and the formulation of products must be tailored to design the desired structure and to improve the reconstitution property.

Macadamia oil-based oleogels as cocoa butter alternatives: Physical properties, oxidative stability, lipolysis, and application

In this study, macadamia oil-based oleogels were prepared using monoglyceride stearate (MG) as a gelator with a low critical gelation concentration (3.0 wt%). The physical properties of the oleogels were evaluated by polarized light microscopy, Fourier transform infrared spectroscopy, differential scanning calorimetry, X-ray diffraction, texture and rheological analysis. And the lipid digestion and oxidative stability of the macadamia oil were determined by pH titration and accelerated oxidation test, respectively. The results showed that the hardness, oil binding capacity, and thermal stability of the oleogels increased with increasing MG concentration, which was attributed to the formation of a network of MG crystals held together by van der Waals interactions and hydrogen bonds. Rheological analysis indicated that all the oleogels exhibited a thermally reversible solid-to-liquid transition and viscoelastic behavior at ambient temperatures. Moreover, the formation of oleogels increased fatty acid release during in vitro lipid digestion and improved the oxidative stability of the macadamia oil. In addition, the potential application of these oleogels as replacements for saturated fats in foods was demonstrated by creating a chocolate product where the cocoa butter was replaced with macadamia oil-based oleogels with a high degree of unsaturation. These results can provide guidance for the preparation of macadamia oil-based oleogels, which may increase their application in foods.

Soybean protein isolate/chitosan complex-rutin microcapsules

Rutin is a flavonoid polyphenol with excellent biological activity, but due to its instability and poor water solubility, the utilization rate is reduced in vivo. Preparation of rutin microcapsules from soybean protein isolate (SPI) and chitosan hydrochloride (CHC) by composite coacervation can improve this restriction. The optimal preparation conditions were as follows: the volume ratio of CHC/SPI 1:8, pH 6, and total concentration of CHC and SPI 2 %. The rutin encapsulation rate and loading capacity of the microcapsules were 90.34 % and 0.51 % under optimal conditions. The SPI-CHC-rutin (SCR) microcapsules had a gel mesh structure and good thermal stability, and the system was stable and homogeneous after 12 d storage. During in vitro digestion, the release rates of SCR microcapsules in simulated gastric and intestinal fluids were 16.97 % and 76.53 %, respectively, achieving a targeted release of rutin in intestinal fluids; and the digested products were found to exhibit superior antioxidant activity to that of free rutin digests, indicating a good protection of microencapsulation on the bioactivity of rutin. Overall, SCR microcapsules developed in this study effectively enhanced the bioavailability of rutin. The present work provides a promising delivery system for natural compounds with low bioavailability and stability.

Recent Advances in the Microencapsulation of Essential Oils, Lipids, and Compound Lipids through Spray Drying: A Review

In recent decades, the microcapsules of lipids, compound lipids, and essential oils, have found numerous potential practical applications in food, textiles, agricultural products, as well as pharmaceuticals. This article discusses the encapsulation of fat-soluble vitamins, essential oils, polyunsaturated fatty acids, and structured lipids. Consequently, the compiled information establishes the criteria to better select encapsulating agents as well as combinations of encapsulating agents best suited to the types of active ingredient to be encapsulated. This review shows a trend towards applications in food and pharmacology as well as the increase in research related to microencapsulation by the spray drying of vitamins A and E, as well as fish oil, thanks to its contribution of omega 3 and omega 6. There is also an increase in articles in which spray drying is combined with other encapsulation techniques, or modifications to the conventional spray drying system.

Plant protein-based emulsions for the delivery of bioactive compounds

Emulsion-based delivery systems (EBDSs) can be used as effective carriers for bioactive compounds (bioactives). Recent studies have shown that plant proteins (PLPs) have the potential to be utilized as stabilizers of emulsions for loading, protection and delivery of bioactives. Different strategies combining physical, chemical and biological techniques can be applied for alteration of the structural characteristics and improving the emulsification and encapsulation performance of PLPs. The stability, release, and bioavailability of the encapsulated bioactives can be tailored via optimizing the processing conditions and formulation of the emulsions. This paper presents cutting-edge information on PLP-based emulsions carrying bioactives in terms of their preparation methods, physicochemical characteristics, stability, encapsulation efficiency and release behavior of bioactives. Strategies applied for improvement of emulsifying and encapsulation properties of PLPs used in EBDSs are also reviewed. Special emphasis is given to the use of PLP-carbohydrate complexes for stabilizing bioactive-loaded emulsions.

Constitution and reconstitution of microcapsules with high diacylglycerol oil loading capacity based on whey protein isolate / octenyl succinic anhydride starch/ inulin matrix

The aim of this study was to constitute microcapsule systems with high oil loading capacity by octenyl succinic anhydride (OSA) starch, whey protein isolate (WPI) and inulin (IN) substrates to provide a new method for encapsulating diacylglycerol oil. Specifically, this study characterizes the physicochemical properties and reconstitution capacity of highly oil loading diacylglycerol microcapsules by comparing the wall encapsulation capacity of the binary wall system OSA-IN, WPI-IN and the ternary wall system WPI-OSA (1:9, 5:5, 9:1)-IN for diacylglycerol oil. It was found that WPI-OSA (5:5)-IN significantly improved the water solubility of microcapsules (86.11 %) compared to OSA-IN microcapsules, and the addition of WPI made the surface of microcapsules smoother and increased the thermal stability and solubility of microcapsules; the addition of OSA enhanced the wettability of microcapsules compared to WPI-IN. In addition, WPI-OSA (5:5)-IN microcapsules have the highest encapsulation efficiency (96.03 %), high emulsion stability after reconstitution, and the smallest droplet size (212.83 nm) after 28 d. Therefore, the WPI-OSA-IN composite system is suitable for the production of highly oil-loaded microencapsulated systems with excellent reconstitution ability to expand the application of diacylglycerol oil.

Degradation kinetics of rutin encapsulated in oil-in-water emulsions: impact of particle size

BACKGROUND

Rutin is a natural bioactive flavonoid that is poor in water solubility and chemical stability. Encapsulation can be used to protect bioactive molecules from chemical or physical decomposition during food processing and storage. Thus, the effect of initial particle size on the ability of oil-in-water emulsions to retain rutin during storage was investigated.

RESULTS

Rutin was encapsulated in oil-in-water emulsions with different mean surface-weighted diameters: d_3,2  = 0.56 μm (small), 0.73 μm (medium), and 2.32 μm (large). As expected, the resistance of the emulsions to coalescence and creaming during storage increased as the particle size decreased due to weakening of the colloidal and gravitational forces acting on the droplets. The concentration of rutin in the emulsions decreased during storage (28 days), which was mainly attributed to photodegradation of the flavonoid. The loss of rutin from the emulsions during storage was fitted using a second-order equation. The rutin degradation rate constant k decreased and the half-life t_1/2 increased with decreasing droplet size, which was attributed to the stronger encapsulation and light scattering by smaller oil droplets reducing the amount of light that can penetrate into the emulsions.

CONCLUSION

This study has important implications for the design of more efficacious emulsion-based delivery systems for incorporating health-promoting nutraceuticals into foods. © 2022 Society of Chemical Industry.

Chestnut Starch Nanocrystal Combined with Macadamia Protein Isolate to Stabilize Pickering Emulsions with Different Oils

This study investigated the formation and molecular interaction mechanism of chestnut starch nanocrystal (SNC)/macadamia protein isolate (MPI) complexes and their application in edible oil-in-water Pickering emulsion (PE). SNC/MPI complexes were characterized by scanning electron microscopy and particle size analyzer. The PEs stabilized by SNC/MPI complexes were characterized by confocal laser scanning microscopy and rheological measurement. The results showed that hydrogen bonds between the two particles significantly affected the secondary structure and assembly of SNC/MPI complexes at the oil/water interface. The optimal mass ratio of SNC to MPI in the complexes with the best stability was determined as 20:1. The formation of edible oil-in-water PEs stabilized by SNC/MPI complexes significantly improved the oxidative and storage stability of different edible oils (olive oil, walnut oil, edible tea oil, and macadamia oil). These different edible oil-in-water PEs stabilized by SNC/MPI could be used as effective carriers of quercetin with their loading rates higher than 93%.

Improved protective and controlled releasing effect of fish oil microcapsules with rice bran protein fibrils and xanthan gum as wall materials

This study aimed to prepare fish oil microcapsules by freeze-drying an emulsion co-stabilized by rice bran protein fibrils (RBPFs) and xanthan gum (XG) to improve the oxidation stability and controlled release effect. Emulsions stabilized either solely by RBPFs or unfibrillated rice bran protein (RBP) or by a combination of RBP and XG were also fabricated as microcapsule templates for comparison. The rheological properties, particle size, and zeta potential of the emulsions were examined. In addition, the characteristics of the fish oil microcapsules such as surface oil content, encapsulation efficiency, water activity, moisture content, morphological structure, oxidation stability, and digestive performance were also assessed. The rheological properties revealed that the addition of XG increased the storage modulus of the emulsion and reduced the loss modulus and apparent viscosity. At shear rates of 0-100 s^-1, the fish oil emulsion did not exhibit any gel properties or shear thinning. Fibrillation increased the particle size of the fish oil emulsion, whereas adding XG reduced the droplet size. The combination of RBP fibrillation and XG addition provided the highest encapsulation efficiency for fish oil. Fibrillation reduced the water activity and moisture content of the fish oil microcapsules. The anisotropy of the fibrils and the high viscosity of XG produced a layer of wrapping on the continuous heterogeneous surface of the freeze-dried powder particles. RBPF/XG microcapsules stored at 45 °C for 1 month had the lowest peroxide value and thiobarbituric acid value, the lowest surface oil content, and the lightest yellowness. These results suggest that the combination of RBPFs and XG provides better encapsulation and protective effects for fish oil microcapsules. Upon simulated digestion, the microcapsules containing XG and RBPFs exhibited a more favorable controlled release of free fatty acids. These findings indicate that microcapsules formed from emulsions co-stabilized by XG and RBPFs are suitable for encapsulating fish oil in functional foods.

Novel angiotensin-converting enzyme (ACE) inhibitory mechanism of peptides from Macadamia integrifolia antimicrobial protein 2 (MiAMP2)

This work aimed to identify novel angiotensin-converting-enzyme (ACE) inhibitory peptides from Macadamia integrifolia antimicrobial protein 2 (MiAMP2). The MiAMP2 protein was hydrolyzed through in silico digestion, and the generated peptides were screened for ACE inhibitory activity. The in silico enzyme digestion results revealed that 18 unreported peptides were obtained using AHTPDB and BIOPEP-UWM, and none were thought to be toxic based on absorption, distribution, metabolism, and excretion (ADMET) prediction. PGPR, RPLY, MNPQR, and AAPR were predicted to exhibit good biological activity. The molecular docking results revealed that the four peptides tightly bound to the active pocket of ACE via hydrogen bonds and hydrophobic interactions, among which RPLY and MNPQR bound to ACE more strongly. The in vitro assay results confirmed that RPLY and MNPQR peptides inhibited ACE via competitive manner. These results provide theoretical guidance for the development of novel foodborne antihypertensive peptides from Macadamia nut proteins. PRACTICAL APPLICATIONS: This study provides new insight on the inhibitory potential of Macadamia nut peptides against ACE, which may be further applied to the development of antihypertensive peptides in the medical industry.

Microcapsules with slow-release characteristics prepared by soluble small molecular starch fractions through the spray drying method

The utilization of starch in the food and medical industry can be facilitated by using new non-chemical methods to make starch the only wall material to encapsulate microcapsules. In this study, soluble small molecular fraction obtained from corn starch by gelatinization and centrifugation methods and commercial soluble starch were used independently to encapsulate oil under the condition that wall material and core material were 2:1. Molecular weight of these starch fractions was measured firstly. The peak molecular weight of the soluble small molecular fraction of corn starch and commercial soluble starch was 3.537 × 105 Da and 2.720 × 104 Da, respectively. Basic physicochemical characteristics and application characteristics of the microcapsules were then characterized and compared. The soluble small molecular fraction of corn starch encapsulated microcapsule and the commercial soluble starch encapsulated microcapsule had high encapsulation efficiency (higher than 88%), high boiling water solubility (higher than 74%), high rehydration stability (higher than 2 h). Most importantly, the encapsulated oil of these microcapsules could be slowly released under the action of α-amylase and amyloglucosidase. Overall, both the soluble small molecular fraction of corn starch and commercial soluble starch could be used as microcapsule wall materials and might have great application potential in food and medicine.

Prediction and evaluation of the 3D structure of Macadamia integrifolia antimicrobial protein 2 (MiAMP2) and its interaction with palmitoleic acid or oleic acid: An integrated computational approach

This study investigated the physicochemical properties and 3D structure of Macadamia integrifolia antimicrobial protein 2 (MiAMP2) and its interaction with palmitoleic acid (POA) or oleic acid (OA) in macadamia oil. The 3D structure of MiAMP2 was constructed for the first time by ab initio modelling using the TrRosetta server. The results showed that MiAMP2 was highly hydrophilic and had seven disulfide bonds and higher α-helix and β-sheet/turn contents. Molecular simulation showed that the hydrophobic pocket of MiAMP2 created a favourable environment for the binding of POA and OA. Free energy landscape and independent gradient model (IGM) analyses revealed that hydrogen bonds and van der Waals forces were the major driving forces stabilizing complexes formed by MiAMP2 and POA or OA. The present study provides a theoretical basis and new insight for the future development and utilization of macadamia nut protein in the food industry.