Wood Hemicelluloses as Innovative Wall Materials for Spray‑Dried Microencapsulation of Berry Juice : Part 1—Effect of Homogenization Techniques on their Feed Solution Properties

The use of wood hemicelluloses, including galactoglucomannans (GGM) and glucuronoxylans (GX), in spray-dried microencapsulation of bioactive compounds has not been reported. Our study aims to investigate the benefts of spray-dried GGM and GX powders (sGGM and sGX) along with the efects of homogenization techniques (magnetic stirring, ultrasonication, and a combination of UltraTurrax homogenization and microfuidization) on the physicochemical properties of feed solutions (10–20%, w/w). Feed solutions of bilberry juice with sGGM, sGX, and mixtures of either sGGM or sGX with methylcellulose (MC) or carboxymethylcellulose (CMC) were examined to produce highly stable feed solutions for spray-dried microencapsulation. The efects of ultrasonication amplitudes (30–80%) on the viscosity and particle size distribution of sGGM feed solutions were more profound than observed in their sGX counterparts. Unlike sGX feed solutions, sGGM feed solutions homogenized by ultrasonication and microfuidization formed a gel-like structure. Microfuidization also caused a loss of total anthocyanin content (TAC) of the feed solutions. Magnetic stirring resulted in no gel formation and in the lowest viscosity of the feed solutions; hence, it is an effective method for preparing hemicellulose feed solutions. sGGM and sGX powders have high heat stability with melting temperatures of 170–180 °C. The sGGM+CMC combination was more stable over 1 week of storage than the sGGM and sGX feed solutions. Storing the feed solutions reduced TAC and increased sGGM viscosity. Our results indicated that GGM and GX have high potential for use as wall materials in the spray-dried microencapsulation of bioactive compounds.Peer reviewe

Wood hemicelluloses as sustainable wall materials to protect bioactive compounds during spray drying of bilberries

The most widely-used wall materials for spray-dried microencapsulation have limitations in cost-effectiveness, health benefits and sustainability. Wood hemicelluloses, by-products of the forestry industry, including gal-actoglucomannans and glucuronoxylans have the potential to be utilized as innovative wall materials. This study investigated the applicability of galactoglucomannan and glucuronoxylan and their mixtures with carboxy-methylcellulose as wall materials for microencapsulation of bilberry juice, in comparison to gum arabic. The results indicated that galactoglucomannan and glucuronoxylan have a relatively high anthocyanin encapsulation efficiency (71-73%), which was similar to that of gum arabic (76%). The addition of carboxymethylcellulose reduced the encapsulation efficiency of wood hemicelluloses to 46-54%. Microencapsulated powders prepared with wood hemicelluloses were considerably higher in total phenolic content and antioxidant activities than those prepared with gum arabic, and mixtures of wood hemicelluloses with carboxymethylcellulose. The results indicate that wood hemicelluloses are efficient wall materials for spray-dried microencapsulation of bioactive compounds.Peer reviewe

Batch Stirred-Tank Green Extraction of Salvia fruticosa Mill. Polyphenols Using Newly Designed Citrate-Based Deep Eutectic Solvents and Ultrasonication Pretreatment

A series of citrate salts were tested as hydrogen bond acceptors to synthesize deep eutectic solvents (DES) based on lactic acid and glycerol, used as hydrogen bond donors. The DES produced were then screened to identify the highest performing system for the effective extraction of polyphenolic phytochemicals from the medicinal plant Salvia fruticosa Mill. (Greek sage). The most efficacious DES was the one composed of lactic acid and sodium citrate dibasic, at a molar ratio of 15:1 (LA-SCDB15). Furthermore, for the first time there has been evidence concerning DES pH and extraction efficiency. Using this solvent, a batch, stirred-tank extraction process was developed, by employing ultrasonication pretreatment and response surface methodology. The optimal settings determined were stirring speed 900 rpm, proportion of DES/water 77% (w/v), and ultrasonication pretreatment time 15 min. By adjusting these optimal settings, the predicted maximum total polyphenol yield was calculated to be 79.93 ± 1.92 mg gallic acid equivalents g−1 dry mass. The examination of temperature effects demonstrated that the batch, stirred-tank extraction stage was very energy-efficient, with a barrier of 7.64 kJ mol−1. Comparison of the extraction of Salvia fruticosa polyphenols with other green processes previously developed, illustrated the high extraction capacity of LA-SCDB15. The major polyphenols identified in the extracts produced under optimized settings were chlorogenic acid, luteolin 7-O-glucuronide and rosmarinic acid

Hydroglycerolic Solvent and Ultrasonication Pretreatment: A Green Blend for High-Efficiency Extraction of Salvia fruticosa Polyphenols

Salvia fruticosa Miller, also known as Cretan or Greek sage, is a medicinal plant with significant biological properties, which are largely ascribed to its polyphenolic composition, but there is to-date a scarcity of green and sustainable processes for efficient polyphenol extraction from this plant. The objective of this study was the implementation of an extraction process that would combine a green solvent based on glycerol, a biodiesel industry by-product, and ultrasonication pretreatment. Ultrasonication for 40 min followed by stirred-tank extraction was shown to provide significantly higher total polyphenol yield than mere stirred-tank extraction, while kinetics indicated 50 °C as the most favorable temperature, with the yield being 92 mg gallic acid equivalents (GAE) per g dry mass. Comparison of this method with a previously developed one that used methyl β-cyclodextrin revealed that the extracts obtained had similar antioxidant activity, and yield in major polyphenols including luteolin 7-O-glucuronide and rosmarinic acid was virtually equal. The current process is proposed as a sustainable and effective methodology for the generation of polyphenol-enriched extracts from S. fruticosa, which could be used as effective food antioxidants/antimicrobials and/or cosmetic constituents

High-Performance Green Extraction of Polyphenolic Antioxidants from Salvia fruticosa Using Cyclodextrins: Optimization, Kinetics, and Composition

S. fruticosa, collectively known as Cretan sage, is a medicinal plant to which a number of bioactivities have been attributed. In spite of its importance in nutrition and pharmacy, reports on the extraction of major polyphenols using sustainable processes are particularly limited. In this study, three common cyclodextrins, namely, methyl β-cyclodextrin (m-β-CD), hydroxypropyl β-cyclodextrin (HP-β-CD), and β-cyclodextrin (β-CD), were tested as green boosters of aqueous extraction of polyphenols from aerial parts of S. fruticosa. To examine simultaneously important extraction parameters, including the concentration of cyclodextrins (CCD), pH, and liquid-to-solid ratio (RL/S), a Box–Behnken design was chosen, with three central points. Temperature effects on the extraction yield were also considered, by carrying out kinetics. The results showed that m-β-CD was the most effective extraction booster, providing total polyphenols yields that amounted to 98.39 mg gallic acid equivalents g−1 dry mass. The kinetic assay demonstrated that extraction was highly effective at 80 °C, increasing significantly polyphenol yield, as well as the ferric-reducing power and antiradical activity of the extracts. It was also proven that extraction with m-β-CD was the least energy-demanding process. Liquid chromatography-tandem mass spectrometry examination revealed that m-β-CD might possess higher affinity for luteolin 7-O-glucuronide extraction, but β-CD for rosmarinic acid extraction

Gel characteristics of low-acetyl spruce galactoglucomannans

Galactoglucomannans (GGM) recovered from abundant forest industry side-streams has been widely recognized as a renewable hydrocolloid. The low molar mass and presence of O-acetyl side-groups results in low viscous dispersions and weak intermolecular interactions that make GGM unsuitable for hydrogel formation, unless forcefully chemically derivatized and/or crosslinked with other polymers. Here we present the characterization of hydrogels prepared from GGM after tailoring the degree of acetylation by alkaline treatment during its recovery. Specifically, we investigated gel characteristics of low-acetyl GGM dispersions prepared at varied solid concentrations (5, 10 and 15 %) and pH (4, 7 and 10), and then subjected to ultrasonication. The results indicated that low-acetyl GGM dispersions formed gels (G′ > G″) at all other studied solid concentration and pH level combinations except 5 % and pH 4. High pH levels, leading to further removal of acetyl groups, and high solid concentration facilitated the gel formation. GGM hydrogels were weak gels with strong shear-thinning behavior and thixotropic properties, and high hardness and water holding capacity; which were enhanced with increased pH and solid concentration, and prolonged storage time. Our study showed the possibility to utilize low-acetyl GGM as mildly processed gelling or thickening agents, and renewable materials for bio-based hydrogels.Peer reviewe

Combination of carboxymethylcellulose and wood hemicelluloses to enhance encapsulation efficiency and microcapsule wall thickness

Wood hemicelluloses have been used as a wall material for spray-dried microencapsulation of polyphenols. Nevertheless, their incomplete water solubility could negatively impact their encapsulation efficiency (EE) and the formation of a complete protective layer, which might be alleviated synergistically by combining them with carboxymethylcellulose (CMC). Here, we explored the effects of CMC addition (0.5–3.0 %, w/w of WM) on the capacity of galactoglucomannans (GGM) and glucuronoxylans (GX) to retain bioactive compounds of bilberry during spray drying; and its contribution to the formation of wall thickness. The results revealed that EE of GGM and GX increased by 4–8 % with the CMC addition at 0.5 %, but significantly declined at higher CMC concentrations. Adding CMC improved the microcapsules' antioxidant activities, surface smoothness, and solubility, but had no effect on their particle size, thermal properties, amorphous structure, or moisture content. The majority of the GGM and GX microcapsules had a hollow internal structure surrounded by continuous wall matrix with a thickness of about 2.3–2.6 μm, which increased to 3.1–3.5 μm with the addition of 0.5 % CMC. Therefore, using CMC at an optimized proportion as a co-encapsulant improved wood hemicelluloses' ability to protect bioactive compounds during spray drying and enhanced microcapsule wall formation

Effects of pH and temperature of ultrafiltration on the composition and physicochemical properties of hot-water-extracted softwood galactoglucomannans

The recovery of softwood galactoglucomannans (GGM) by pressurized hot water extraction and further con-centration by membrane filtration followed by spray drying yield biopolymers suitable as raw materials for renewable products. GGM are often characterized as having low viscosity in water and excellent emulsion sta-bilizing capacity, enhanced by lignin structures co-extracted with GGM. To reduce membrane fouling during filtration and subsequently to increase product yield, the pH and temperature of GGM liquor can be increased, but effects of such conditions on properties of recovered GGM have not been well understood. Herein, we sys-tematically varied the ultrafiltration pH (6-10) and temperature (30-60 degrees C) and characterized the composition and physicochemical properties of spray-dried GGM powders in comparison with freeze-dried (fGGM) and ethanol precipitated GGM (eGGM). The GGM samples ultrafiltrated at 60 degrees C and pH 10 (GGM-10/60) showed lower molar mass (2200 Da), degree of acetylation (0.09) and absolute zeta-potential (13 mV) than the other ultrafiltrated samples at pH (6-10) and temperature (30-45 degrees C) (3200-3700 Da, 0.11-0.15 and 23-32 mV, respectively). These differences could explain the unique gel formation capacity of GGM-10/60 after ultra-sonication, which opens new prospects in GGM applications such as thickening agents or in 3D printing. The present results allow the design of biorefinery processes to obtain GGM with desirable properties for specific applications.Peer reviewe

Effects of pH and temperature of ultrafiltration on the composition and physicochemical properties of hot-water-extracted softwood galactoglucomannans

The recovery of softwood galactoglucomannans (GGM) by pressurized hot water extraction and further concentration by membrane filtration followed by spray drying yield biopolymers suitable as raw materials for renewable products. GGM are often characterized as having low viscosity in water and excellent emulsion stabilizing capacity, enhanced by lignin structures co-extracted with GGM. To reduce membrane fouling during filtration and subsequently to increase product yield, the pH and temperature of GGM liquor can be increased, but effects of such conditions on properties of recovered GGM have not been well understood. Herein, we systematically varied the ultrafiltration pH (6− 10) and temperature (30–60 ◦C) and characterized the composition and physicochemical properties of spray-dried GGM powders in comparison with freeze-dried (fGGM) and ethanol precipitated GGM (eGGM). The GGM samples ultrafiltrated at 60 ◦C and pH 10 (GGM-10/60) showed lower molar mass (2200 Da), degree of acetylation (0.09) and absolute ζ-potential (13 mV) than the other ultrafiltrated samples at pH (6− 10) and temperature (30–45 ◦C) (3200–3700 Da, 0.11–0.15 and 23–32 mV, respectively). These differences could explain the unique gel formation capacity of GGM-10/60 after ultrasonication, which opens new prospects in GGM applications such as thickening agents or in 3D printing. The present results allow the design of biorefinery processes to obtain GGM with desirable properties for specific applications.</p