Kinetics study of acid hydrolysis of citrus pectin in hydrothermal process

Higher molecular weight pectin inhibits ice crystal growth and its effect on the microstructural and physical properties of pectin cryogels

Understanding the formation of ice crystals is essential for tailoring the microstructure and physical properties of cryogels. This study investigated the effects and mechanisms of pectin molecular weight (Mw) on impacting ice crystal formation. Pectin fractions various Mw (10.13-212.20 kDa) were prepared by hydrothermal method. The solution of high Mw pectin fractions exhibited higher contact angle, lower water freedom, and stronger adsorption of water molecules. The splat experiment and molecular dynamic (MD) results confirmed that higher Mw pectin have stronger ice crystal growth inhibition activity than lower Mw pectin. Furthermore, the pore size distribution of the cryogel increased from 98-203 μm to 105-267 μm as the molecular weight decreased from 212.2 kDa to 121.0 kDa. Additionally, in the higher Mw pectin cryogel, stronger mechanical strength was observed. These findings suggested that changing the molecular weight of pectin has the potential to regulate the ice crystal growth, microstructure and physical properties of frozen products.

Pectin extracted from red dragon fruit (Hylocereus polyrhizus) peel and its usage in edible film

Pectin was extracted from red dragon fruit (Hylocereus polyrhizus) peel using two different extraction methods: subcritical water extraction (SCWE) and conventional acid extraction (AE), from two different types of peels, fresh peel puree and dried peel powder. SCWE method on fresh peel puree showed an ∼18.88 % increase in pectin yield compared to AE. Extracted pectin is classified as low methoxyl pectin (DE: 8.51-50.64 %), with an average molecular weight ranging from 115.23 kDa to 577.84 kDa and a Gal-A content of 44.09 % - 53.90 %. The potential of pectin from fresh peel puree to be applied as a biodegradable film was further explored. Different pectin concentrations (3-5 % w/v) were used to prepare the films. Regarding the film performance, PF-S5, which was produced from SCWE with 5 % of pectin concentration, exhibits better thermal stability (Tdmax 250 °C, residue of 28.69 %) and higher moisture barrier (WVP 5.59 × 10-11 g.cm-1.s-1.Pa-1). In comparison, PF-A showed lower water solubility (45.14-69.15 %), higher water contact angle (33.01° - 44.35°), and better mechanical properties (TS: 2.12-4.11 MPa, EB: 48.72-61.39 %). Higher molecular weight accompanied by higher DE and Gal-A content contributes to better pectin film properties.

Quantitative determination of galacturonic acid in pectin and pectin products by combined pectinase hydrolysis and HPLC determination

Pectin is a complex heteropolysaccharide with a predominantly galacturonic acid (GalA) main chain and various branching sugars, leading to some analytical and quantitative determination challenges. By comparison with various acid hydrolysis methods, an effective and precise hydrolysis method for GalA determination from pectin was investigated using a combination of pectinase hydrolysis (PH) and HPLC determination, which was named the PH-HPLC method. With a pectinase loading of 2250 U/g pectin, 4.0 g/L commercial pectin was almost completely hydrolysed to the intact and detectable GalA at 50 °C after 24 h, for quantitative determination by HPLC. Acid-catalysis methods showed obvious disadvantages in terms of GalA degradation or incomplete hydrolysis of pectin, resulting in imprecise determination results. Moreover, the PH-HPLC method was employed for the quantitative determination of GalA in three common natural pectin feedstocks and indicated 45.5-233.1% higher content of GalA than the acid hydrolysis method. Thus, the PH-HPLC method is demonstrated to be a precise approach for analysing and quantifying the GalA of pectin and respective feedstock.

Effects of Drug-Free Pectin Hydrogel Films on Thermal Burn Wounds in Streptozotocin-Induced Diabetic Rats

This study aims to examine the influence of drug-free pectin hydrogel films on partial-thickness burn wounds using streptozotocin-induced diabetic rats as the animal model. Thirty male Sprague Dawley rats were included in the wound healing study, and scalding water was used to produce wounds in the dorsum region of the rats. Two different formulations of pectin hydrogel films, PH 2.5% and PH 5%, were prepared using a solvent evaporation method. MEBO^® (moist exposed burn ointment), a commercial herbal formulation was used as a positive control. The progress of the wound healing was observed and compared between untreated normal rats, untreated diabetic rats, diabetic rats treated with MEBO^®, diabetic rats treated with PH 2.5%, and diabetic rats treated with PH 5%. The results showed that diabetic rats treated with PH 5% healed faster than the untreated diabetic rats and diabetic rats treated with PH 2.5%. Interestingly, the diabetic rats treated with PH 5% healed as well as diabetic rats treated with MEBO^®, where wounds were healed entirely on day 20. Nevertheless, both PH 2.5% and PH 5% showed a greater zone of inhibition than MEBO^® when tested against Staphylococcus aureus.