Production of chitosan from shrimp shell using ultrasound followed by subcritical water hydrolysis.

The interest in shrimp shell valorization has been growing in line with sustainability goals. Therefore, the main objective of this study was to obtain chitosan from shrimp shell using ultrasound followed by subcritical water treatment. Ultrasonication of shells was performed at 600 and 1200 W for 5 min. Then, shells were hydrolyzed at 140-260 °C and 50 bar for 10-60 min followed by demineralization using citric acid, bleaching using hydrogen peroxide and deacetylation using sodium hydroxide solution. The highest deproteination (80.93 %) was obtained by ultrasonication at 1200 W/5 min followed by subcritical water hydrolysis at 260 °C/50 bar/60 min, where the residue with a yield of 10.56 %, whiteness index of 60.42, degree of deacetylation of 64.27 %, relative crystallinity of 32.66 % and similar functional groups to the commercial sample was obtained. These results indicated that the combination of ultrasound with subcritical water is promising to valorize shrimp shell towards production of value-added compounds.

Three-Dimensional Printing Parameter Optimization for Salmon Gelatin Gels Using Artificial Neural Networks and Response Surface Methodology: Influence on Physicochemical and Digestibility Properties.

This study aimed to optimize the 3D printing parameters of salmon gelatin gels (SGG) using artificial neural networks with the genetic algorithm (ANN-GA) and response surface methodology (RSM). In addition, the influence of the optimal parameters obtained using the two different methodologies was evaluated for the physicochemical and digestibility properties of the printed SGG (PSGG). The ANN-GA had a better fit (R2 = 99.98%) with the experimental conditions of the 3D printing process than the RSM (R2 = 93.99%). The extrusion speed was the most influential parameter according to both methodologies. The optimal values of the printing parameters for the SGG were 0.70 mm for the nozzle diameter, 0.5 mm for the nozzle height, and 24 mm/s for the extrusion speed. Gel thermal properties showed that the optimal 3D printing conditions affected denaturation temperature and enthalpy, improving digestibility from 46.93% (SGG) to 51.52% (PSGG). The secondary gel structures showed that the ß-turn structure was the most resistant to enzymatic hydrolysis, while the intermolecular ß-sheet was the most labile. This study validated two optimization methodologies to achieve optimal 3D printing parameters of salmon gelatin gels, with improved physicochemical and digestibility properties for use as transporters to incorporate high value nutrients to the body.

Poly-l-lactic acid (PLLA)/anthocyanin nanofiber color indicator film for headspace detection of low-level bacterial concentration.

Since bacterial contamination is a significant threat to humans, early detection is essential to safeguard dietary safety and physical health. Here, a nanofiber color indicator film based on poly-l-lactic acid (PLLA) as the support and anthocyanin as the indicator material was prepared by electrostatic spinning. It was found that the PLLA/0.8CY nanofiber color indicator film was hydrophobic (the water contact angle of 102.4°) and contained uniform nanofibers with an average diameter of 750 nm. In addition, the film's humidity insensitivity, reusability, color stability, and ammonia sensitivity (the limits of detection 35.39 ppm) made the film environmentally friendly and more accurate and faster for bacterial detection. The film was able to sense 102 CFU/mL of gram-positive and negative bacteria after the model strain E. coli and L. monocytogene. Thus, the PLLA/0.8CY nanofiber color indicator film was able to perform headspace nondestructive detection of low-level bacterial contamination.

Multi-responsive poly N-isopropylacrylamide/poly N-tert-butylacrylamide nanocomposite hydrogel with the ability to be adsorbed on the chitosan film as an active antibacterial material.

Nanocomposite hydrogel composed of Poly N-isopropylacrylamide (PNIPAM), poly N-tert-Butylacrylamide (PBAM) and poly acrylic acid (PAA) was synthesized by free radical polymerization, and then thymol was embedded in it, to design an active antibacterial material that could control release. The characterization of products used SEM, AFM, FTIR, Zeta sizer to analyze the sensitivity of nanoparticles to pH, temperature and salt ions, and the agar diffusion method was used to determine the antibacterial effect of the polymers. The results showed that nanoparticles had pH, temperature and salt ion responsiveness, PNIPAM/PBAM (65:35) nanoparticles loaded thymol had longer release time (more than 24 h) at lower temperature than that (around 6 h) at high temperature. In addition, the nanoparticles could also be adsorbed on the chitosan film, which makes it have a wider range of applications. All thymol-loaded nanoparticles showed antibacterial activity against both B. subtilis and E. coli, while the chitosan film adsorbed nanoparticles showed weak effect, which was related to the controlled and slow release of bacteriostatic agents. Thus, these copolymers have potential value in the development and application of bacteriostatic packaging films for food.

Ultrasound processing of rutin in food-grade solvents: Derivative compounds, antioxidant activities and optical rotation.

The effect of ultrasound was studied on the flavonoid rutin to understand its hydrolysis to aglycones, antioxidant capacity and optical rotation. The total phenolic content increased >56% at 3.6-36 kJ/cm3, indicating production of phenolic compounds. In the water media, at 27 kJ/cm3 and 47 °C, the total flavonoid content increased from control 0.26 ± 0.01 to 0.45 ± 0.02 mg catechin equivalent/mg rutin hydrate. Quercetin yield in citric acid media increased with change in energy density from 0.34 ± 0.09% at 0.1 kJ/cm3 (68 °C) to 2.23 ± 0.04% at 7.0 kJ/cm3 (86 °C). A plummeting effect was only observed in water media after 27 kJ/cm3 by FRAP (47 °C) and DPPH (86 °C) antioxidant activities, indicating that the presence of solutes (citric acid and NaCl) after 27 kJ/cm3 reduced degradation of flavonoids. Furthermore, ultrasonication increased levorotatory rutin enantiomers, that can be used to further modify physico-chemical properties of other food components.

Ultrasound-assisted modification of rutin to nanocrystals and its application in barley starch pyrodextrinization.

Ultrasound technology offers low cost and efficiency in nanodrug production and therefore was selected to investigate the formation of rutin nanocrystals, and its incorporation in barley starch pyrodextrin. Ultrasonication of rutin (600 W in water, citric acid and NaCl media) was carried out prior to rutin-barley starch pyrodextrinization (90 °C, 1 h). The ultrasound treated rutin (UTR) nanocrystal strands had <820 nm in diameter but shorter lengths from treatments at 27 and 36 kJ/cm3 (47 °C) compared to 3.9 and 7.0 kJ/cm3 (86 °C). All UTR showed color changes from yellow (control) to green and greenish-yellow. Also, thermal analysis indicated that UTR-citric acid had two polymorphs identified by melting peaks at 129.97 °C and 145.04 °C and an earlier decomposition at 179.47 °C compared to 244 °C (control). Rutin/UTR had no significant influence on the production of maltooligosaccharides (18-75 mg/mL of dextrin syrup). Ultrasonication enhanced rutin properties for oral delivery.

Clove essential oil emulsion-filled cellulose nanofiber hydrogel produced by high-intensity ultrasound technology for tissue engineering applications.

High-intensity ultrasound (HIUS) was used to produce emulsion-filled cellulose nanofiber (CNF) hydrogel using clove essential oil (0.1, 0.5 and 1.0 wt%) as dispersed phase towards tissue engineering applications. The novel encapsulating systems obtained using HIUS specific energy at the levels of 0.10, 0.17, and 0.24 kJ/g were characterized by oil entrapment efficiency, microstructure, water retention value, color parameters, and viscoelastic properties. Freeze-dried emulsion-filled CNF hydrogels were characterized by porosity and swelling capacity. In addition, human gingival fibroblast cell cytocompatibility tests were performed to evaluate their potential applications as tissue engineering scaffold. The clove essential oil content strongly affected the oil entrapment efficiency, water retention value, color difference and whiteness of the prepared emulsion-filled CNF hydrogel. And, the HIUS energy only affected the yellowness of the emulsion-filled CNF hydrogel. Via HIUS processing, the CNF hydrogel successfully acted as a continuous phase in the emulsion-filled gel system with maximum oil entrapment efficiency of 34% when 0.5 wt% clove essential oil was added to the system. The encapsulating systems had predominantly gel-like property with maximum elastic modulus of 411 Pa. Furthermore, the emulsion-filled CNF hydrogels with the addition of clove essential oil up to 0.5 wt% indicated good cell viability rates (74-101%) to human gingival fibroblast cells. The newly developed clove essential oil emulsion-filled CNF hydrogel shows desirable cytocompatibility characteristics and can be considered as an alternative scaffold for tissue engineering applications.

High-intensity ultrasound-assisted formation of cellulose nanofiber scaffold with low and high lignin content and their cytocompatibility with gingival fibroblast cells.

Cellulose nanofiber (CNF) hydrogels with low lignin (8%) (LL-CNF) and high lignin (18%) (HL-CNF) content were produced at nominal powers of 240, 720 and 1200 W using high-intensity ultrasound technology (HIUS). Freeze-dried CNF hydrogels were evaluated as scaffolds for gingival fibroblast cells proliferation aiming biomedical applications. HIUS processing improved the dispersibility of the CNF and increased the water retention value by more than 5 times. The LL-CNF had a maximum fibrillation yield of 46 wt.%, whereas the HL-CNF had a maximum fibrillation yield of 40 wt.% at nominal power of ≥720 W. Regardless of the lignin content, the CNF hydrogels exhibited a typical elastic gel-like behavior with the highest elasticity of 263 Pa. After freeze-drying, the CNF aerogels had porosity ≥ 96.8%, and swelling capacity up to 42.1 g PBS/g aerogel. Moreover, the cell proliferation assay showed no differences in proliferation among the LL-CNF and HL-CNF scaffolds up to 11 days. Therefore, CNF scaffolds prepared with lignin content up to 18% present promising application in the biomedical field.

Xylooligosaccharides chemical stability after high-intensity ultrasound processing of prebiotic orange juice.

The effects of the high-intensity ultrasound (HIUS) technology at the nominal powers of 300, 600, 900, and 1200 W were evaluated on the chemical stability of xylooligosaccharides (XOS) used to enrich orange juice. The ultrasound energy performance for each nominal power applied to the XOS-enriched orange juice was determined by calculating acoustic powers (W), HIUS intensity (W/cm2), and energy density (kJ/mL). Physicochemical properties (pH and soluble solid content), organic acid content (ascorbic, malic, and citric acids), total phenolic content (TPC), antioxidant activity by the FRAP (Ferric reducing ability of plasma) method, sugar (glucose, fructose, and sucrose), and XOS (xylobiose, xylotriose, xylotetraose, xylopentaose, and xylohexaose) content were determined. The pH and soluble solid content did not change after all HIUS treatments. The HIUS process severity was monitored by quantifying ascorbic acid content after the treatments. A significant linear decrease in the ascorbic acid content was observed in prebiotic orange juice with the HIUS process intensification by increasing nominal power. The malic acid and citric acid contents had similar behavior according to the HIUS process intensification. The nominal power increase from 300 to 600 W increased the concentration of both organic acids, however, the intensification up to 1200 W reduced their concentration in the functional beverage. The TPC and FRAP data corroborated with the results observed for the ascorbic acid content. However, the HIUS processing did not alter sugar and XOS contents. The XOS chromatographic profiles were not modified by the HIUS treatment and presented the same amount of all prebiotic compounds before and after the HIUS treatment. Overall, HIUS technology has been evaluated as a promising stabilization technique for prebiotic beverages enriched with XOS due to their high chemical stability to this emerging technology under severe process conditions.

Antimicrobial activity of bioactive starch packaging films against Listeria monocytogenes and reconstituted meat microbiota on ham.

Contamination with spoilage organisms and Listeria monocytogenes are major concerns for quality and safety of cooked ready-to-eat (RTE) meat products. Thus, the objective of this study was to investigate the use of antimicrobial starch packaging films to control competitive microbiota and L. monocytogenes growth on a RTE ham product. Starch packaging films were prepared with different bioactives, gallic acid, chitosan, and carvacrol, using subcritical water technology. The viability of the incorporated strains on ham in contact with different antimicrobial starch packaging films was examined during 28-day storage period at 4 °C. Starch films with gallic acid had the least effect on ham antimicrobial activity; starch films with chitosan and carvacrol fully inhibited L. monocytogenes growth throughout 4 weeks of storage. RTE meat microbiota was more resistant to the antimicrobials than L. monocytogenes. Starch films loaded with chitosan or chitosan and carvacrol did not fully inhibit growth of RTE meat microbiota but delayed growth of RTE meat microbiota by one to two weeks. Moreover, competitive meat microbiota fully inhibited growth of L. monocytogenes. Therefore, antimicrobial starch packaging films prepared by subcritical water technology used in this study showed a promising effect on inhibiting L. monocytogenes in RTE ham.

Optimization of artemisinin extraction from Artemisia annua L. with supercritical carbon dioxide + ethanol using response surface methodology.

Malaria is a high priority life-threatening public health concern in developing countries, and therefore there is a growing interest to obtain artemisinin for the production of artemisinin-based combination therapy products. In this study, artemisinin was extracted from the Artemisia annua L. plant using supercritical carbon dioxide (SC-CO2 ) modified with ethanol. Response surface methodology based on central composite rotatable design was employed to investigate and optimize the extraction conditions of pressure (9.9-30 MPa), temperature (33-67°C), and co-solvent (ethanol, 0-12.6 wt.%). Optimum SC-CO2 extraction conditions were found to be 30 MPa and 33°C without ethanol. Under optimized conditions, the predicted artemisinin yield was 1.09% whereas the experimental value was 0.71 ± 0.07%. Soxhlet extraction with hexane resulted in higher artemisinin yields and there was no significant difference in the purity of the extracts obtained with SC-CO2 and Soxhlet extractions. Results indicated that SC-CO2 and SC-CO2 +ethanol extraction is a promising alternative for the extraction of artemisinin to eliminate the use of organic solvents, such as hexane, and produce extracts that can be used for the production of antimalarial products.

Hydrophobic lappaconitine loaded into iota-carrageenan by one step self-assembly.

New data on the loading of pH-sensitive lappaconitine loaded into iota-carrageenan (LA-ICG) is provided. This LA-ICG ionic biopolymer was prepared by one step self-assembly. The LA-ICG was characterized in terms of the loading capacity, lappaconitine (LA) releasing behavior, pH-sensitivity, and analgesic properties. Iota-carrageenan (ICG) high loading capacity reached up to 26.18% (w/w). Also, the LA, loaded with ICG, was released faster in an acidic environment than that in neutral or alkaline environments. Animal analgesic experiments showed that the LA-ICG of low molecular weight had earlier onset time and longer duration than the LA. These results suggest that the ICG of low molecular weight has great potential to achieve the synergistic effect of LA. In addition, the ICG can be used as a novel natural polymeric carrier for loading a hydrophobic alkaloid.

Sulfated polysaccharide heparin used as carrier to load hydrophobic lappaconitine.

One-step self-assembly was used to prepare pH-sensitive lappaconitine-loaded low-molecular-weight heparin (LMWH-LA) and to demonstrate that the sulfur group promotes dissolution and has synergistic effect on the analgesic property of lappaconitine (LA). The LMWH-LA was characterized in terms of releasing behavior, pH-sensitivity, analgesic activity and anticoagulation property. The drug loading level of LA in low-molecular-weight heparin (LMWH) reached 24.3% (w/w). The LA, self-assembled in LMWH, released faster in an acidic environment than that in neutral or alkaline environments. Analgesic experiments showed that the LMWH-LA had earlier onset time and longer duration than the LA. Compared with LMWH, the LMWH-LA can reduce clotting time more effectively. These results suggest that the LMWH is a good template and has great potential to achieve synergistic effect of LA. In addition, similar macromolecular structure can be used as a new natural polymeric carrier for loading hydrophobic alkaloids.

Hydrolysis of sweet blue lupin hull using subcritical water technology.

Hydrolysis of sweet blue lupin hulls was conducted in this study using subcritical water technology. Effects of process parameters, such as pressure (50-200 bar), temperature (160-220°C), flow rate (2-10 mL/min), and pH (2-12), were studied to optimize maximum hemicellulose sugars recovery in the extracts. Extracts were analyzed for total hemicellulose sugars, phenolics and organic carbon contents and solid residues left after treatments were also characterized. Temperature, flow rate, and pH had a significant effect on hemicellulose sugar removal; however, the effect of pressure was not significant. The highest yield of hemicellulose sugars in the extracts (85.5%) was found at 180°C, 50 bar, 5 mL/min and pH 6.2. The thermal stability of the solid residue obtained at optimum conditions improved after treatment and the crystallinity index increased from 11.5% to 58.6%. The results suggest that subcritical water treatment is a promising technology for hemicellulose sugars removal from biomass.

Combined Effect of Pressure-Assisted Thermal Processing and Antioxidants on the Retention of Conjugated Linoleic Acid in Milk.

The effect of pressure-assisted thermal processing (PATP) in combination with seven synthetic antioxidants was evaluated on the retention of conjugated linoleic acid (CLA) in enriched milk. Milk rich in CLA was first saturated with oxygen, followed by the addition of either catechin, cysteine, ascorbic acid, tannic acid, gallic acid, caffeic acid or p-coumaric acid (500 mg kg-¹ untreated milk). Samples were treated at 600 MPa and 120 °C up to 15 min of holding time. During PATP, CLA not only oxidized at a slower rate, but also less oxygen was consumed compared to the control (0.1 MPa and 120 °C). In addition, phenolic antioxidants were able to quench dissolved oxygen in samples treated with PATP. For those samples added with gallic acid and catechin, 85% and 75% of the CLA was retained after 15 min of holding time at 600 MPa and 120 °C, respectively. The retention of CLA was enhanced by the application of PATP in combination with gallic acid.

Pressurized aqueous ethanol extraction of ß-glucans and phenolic compounds from waxy barley.

Beta-glucans and phenolics were extracted from waxy barley using pressurized aqueous ethanol in a stirred batch reactor at 25bar and 500rpm. The effect of temperature (135-175°C), extraction time (15-55min) and ethanol content (5-20%) was evaluated. Temperature had an opposite effect on the extraction of both compounds. The higher the temperature, the lower the ß-glucan extraction yield due to fragmentation, but a significant increase on the phenolic recovery was observed. Long extraction times favored the extraction of ß-glucans at low temperatures and phenolics at any temperature. The ethanol content was not statistically significant on the ß-glucan extraction, but helped to maintain the molecular weight of the extracted ß-glucan. To obtain liquid extracts rich in high molecular weight ß-glucans and phenolics, mild conditions of 151°C, 21min and 16% ethanol are needed, leading to 51% ß-glucan extraction yield with a molecular weight of 500-600kDa and 5mgGAE/g barley.

Induction of pilocarpine formation in jaborandi leaves by salicylic acid and methyljasmonate.

Jaborandi seedlings were subjected to different treatments in order to study the induction of pilocarpine in the leaves. In addition four extraction methods were assessed to extract the alkaloid from dried leaves. The highest yielding extraction and recovery was observed when dried leaves were first treated with base and then extracted with chloroform. Salt stress (NaCl), wounding, hypoxia, and N and K omission of the nutrient soln caused reductions in pilocarpine contents. Whereas complete nutrient soln and P omission maintained normal levels of the alkaloid. Salicylic acid and methyljasmonate induced a 4-fold increase of pilocarpine, but this increase was dependent on the concentration and time after exposure.

Extraction of methylxanthines from guaraná seeds, maté leaves, and cocoa beans using supercritical carbon dioxide and ethanol.

New experimental data on the extraction of caffeine from guaraná seeds and maté tea leaves, and theobromine from cocoa beans, with supercritical CO2 were obtained using a high-pressure extraction apparatus. The effect of the addition of ethanol to carbon dioxide on the extraction efficiency was also investigated. Caffeine extraction yields of 98% of the initial caffeine content in both wet ground guaraná seeds and maté tea leaves were obtained. Extractions of caffeine from guaraná seeds and maté tea leaves also exhibited a retrograde behavior for the two temperatures considered in this work. In the removal of theobromine from cocoa beans, a much smaller extraction yield was obtained with longer extraction periods and consequently larger solvent requirements. The results of this study confirm the higher selectivity of CO2 for caffeine in comparison with that for theobromine, and also the influence of other components in each particular natural product on the extraction of methylxanthines. The effect of the addition of ethanol to carbon dioxide on the extraction of methylxanthines was significant, particularly in the extraction of theobromine from cocoa beans. In general, the use of ethanol results in lower solvent and energy requirements and thereby improved extraction efficiency.