Enrichment of Agar Gel with Antioxidant Pectin from Fireweed: Mechanical and Rheological Properties, Simulated Digestibility, and Oral Processing

Abstract

The aims of the study were to evaluate the influence of pectin isolated from fireweed (FP) on the mechanical and rheological properties of agar (A) gel, to investigate the release of phenolic compounds (PCs) and pectin from A-FP gels at simulated digestion in vitro, and to evaluate the oral processing and sensory properties of A-FP gels. The hardness of A-FP gels decreased gradually with the increase in the concentration of FP added (0.1, 0.4, and 1.6%). The hardness of A-FP1.6 gel was 41% lower than A gel. Rheological tests found A gel was a strong physical gel (storage modulus (G′) >>loss modulus (G″)), and the addition of FP up to 1.6% did not significantly change its G’. The G″ value decreased in A-FP gels compared to A gel. The release of galacturonic acid (GalA) was 3.4 ± 0.5, 0.5 ± 0.2, 2.4 ± 1.0, and 2.2 ± 0.7 mg/mL after digestion of A-FP1.6 gel in the oral in vivo phase (OP) and subsequent incubation in simulated gastric (SGF), intestinal (SIF), and colonic (SCF) fluids in vitro. The incubation medium after OP, SGF, and SIF digestion of A-FP1.6 contained 24–64 μg GAE/mL of PCs, while SCF contained 144 μg GAE/mL, supposing a predominant release of antioxidant activity from the gel in the colon. Chewing to readiness for swallowing A-FP gel required less time and fewer chews with less activity of the masseter and temporalis muscles. A-FP1.6 gel had a lower likeness score for taste and consistency and a similar score for appearance and aroma when compared with A gel. Thus, A-FP gels were weakened compared to A gel and required less time and muscle activity for oral processing. A-FP gel had antioxidant activity due to the PCs associated with pectin, while A gel had no antioxidant activity.

Serosal Adhesion Ex Vivo of Hydrogels Prepared from Apple Pectin Cross-Linked with Fe3+ Ions

“…The GalA content was determined by reaction with 3,5-dimethylphenol in the presence of concentrated sulfuric acid [ 34 ]. Briefly, 2 mL of incubation medium was centrifuged at 3000× g for 5 min at 4 °C (Micro 220 R Hettich Zentrifugen, Tuttlingen, Germany).…”

Effect of Hogweed Pectin on Rheological, Mechanical, and Sensory Properties of Apple Pectin Hydrogel

“…Serum release was determined as the weight ratio of the released serum to the initial weight of a hydrogel after compression to 80% of its original height at room temperature [ 53 ].…”

“…EMG activity from the superficial masseter and anterior temporalis was monitored using bipolar electrodes (11 × 25 mm) that were separated from each other by approximately 20 mm. Before EMG recording, participants were instructed to chew freely until it was easy to swallow [ 53 ].…”

“…The gel fragments were transferred to a 20 mL sheathed glass container for further in vitro digestion. In vitro gastrointestinal digestion was approached by a method [ 53 ] using SGF (pH 1.5, 0.08 M HCl, and 0.03 M NaCl), SIF (pH 6.8, 0.05 M KH 2 PO 4 , and 0.02 M NaOH), and SCF (0.01 M KH 2 PO 4 , 0.05 M NaHPO 4 , and pectinase: 1.7 mg/mL). The contents of galacturonic acid and calcium ions were determined in the fluid after each phase of digestion.…”

A Label-Free and Ultrasensitive Prussian Blue-Based Dipstick Sensor for Bacterial and Biofilm Detection

“…Upon addition of Fe 3+ , the sensor turns blue rapidly, which is a simple synthesis of Prussian blue (PB), a well-known mixed-valent compound with a characteristic absorbance peak at ∼700 nm. 31 However, the sensor works only at pH <1.0, which severely hampers the development of the sensor to the solid state, as most of the biodegradable substrates such as agarose and pectin 32 degrade at an acidic pH value. In addition, their sensor fabrication requires tedious sample preparation and longer incubation times, which are not feasible at the household level.…”