Hydrogel Derived from Glucomannan-Chitosan to Improve the Survival of Lactobacillus acidophilus FNCC 0051 in Simulated Gastrointestinal Fluid.

The probiotic encapsulating hydrogel derived from porang (Amorphophallus oncophyllus) glucomannan and chitosan was investigated with regard to its encapsulation efficiency, physical properties, prebiotic activity, and survival under simulated gastrointestinal conditions. The hydrogel's encapsulation efficiency was improved by varying the number of the Lactobacillus acidophilus FNCC 0051, which also served to increase the diameter (2-3 mm), polydispersity index (1.23-1.65), positive zeta potential, whiteness, and brightness of the hydrogel. Moreover, the hydrogel's prebiotic activity score was higher than that of inulin after 24 h of incubation, reflecting its role as a cell encapsulant, particularly when it comes to maintaining cells during exposure to simulated gastrointestinal fluid. The cell viability increased from 86% to 100% when immersed in intestinal juice, which is comparable to the increase achieved using alginate and konjac glucomannan hydrogels. Future animal studies are required to determine the cell viability in actual gastrointestinal conditions and assess the health effects of the hydrogel.

The Application of Polyurethane-LiClO4 to Modify Screen-Printed Electrodes Analyzing Histamine in Mackerel Using a Voltammetric Approach.

Histamine is an important substance that can be applied as a parameter for allergic reactions and food freshness. This study develops a method to produce a histamine sensor based on electrodes modified using polyurethane-LiClO4. A sensor method was developed where this sensor was produced from polyurethane. The application of 4,4'-diphenylmethane diisocyanate (hard compound) and palm kernel oil-based monoester polyol (soft compound) to produce polyurethane (PU) based on bio-polyol. The addition of lithium perchlorate (LiClO4) was done in order to increase the conductivity of PU. The oxidation process was detected using cyclic voltammetry, whereas the electrochemical impedance spectroscopy was used to analyze the conductivity of the polymer. The polyurethane-LiClO4 was attached on a screen-printed electrode (SPE) within 45 min. Moreover, the 1% LiClO4-PU-SPE presented satisfactory selectivity for the detection of histamine in the pH 7.5 solution. The LiClO4-PU-SPE presented a good correlation coefficient (R = 0.9991) in the range 0.015-1 mmol·L-1. The detection limit was 0.17 mmol·L-1. Moreover, the histamine concentration of mackerel samples was detected by the PU-SEP-LiClO4. Several amine compounds were chosen to study the selectivity of histamine detection using SPE-PU-LiClO4. The interference was from several major interfering compounds such as aniline, cadaverine, hexamine, putrescine, and xanthine. The technique showed a satisfactory selective analysis compared to the other amines. A satisfactory recovery performance toward varying concentrations of histamine was obtained at 94 and 103% for histamine at 0.01 and 0.1 mmol·L-1, respectively. The application of PU-SEP-LiClO4 as an electrochemical sensor has a great prospect to analyze histamine content in fish mackerel as a consequence of PU-SEP-LiClO4 having good selectivity and simplicity.

Characterization of glucomannan from Amorphophallus oncophyllus and its prebiotic activity in vivo.

Porang (Amorphophallus oncophyllus) is local perennial plant rich in glucomannan. The aim of this study was to extract and characterize glucomannan from porang tuber and to evaluate its potency as prebiotic in vivo. The research consisted of the following steps, i.e. extraction of glucomannan, evaluation of its physico-chemical properties, and in vivo study. Extraction was done by immersing porang fluor with water at 55 °C followed by coagulating glucomannan using ethanol. Solubility, water holding capacity, viscosity, degree of acetylation, degree of polymerization (DP), and purity of the glucomannan were evaluated. In vivo study was done using thirty-two Wistar rats which were divided into four groups. Each group was treated for 14 days with standard AIN 93 (standard), porang glucomannan, commercial konjac glucomannan, and inulin diet as source of fiber. Bacterial population and chemical properties of digesta were analyzed after intervention. The results of the study indicated that the yield of glucomannan from porang flour was 18.05% with 92.69% purity. Compared to commercial glucomannan, porang glucomannan showed higher solubility (86.4%) and degree of acetylation (13.7%), but lower viscosity (5400 cps), WHC (34.5 g/g), and DP (9.4). Diet supplemented with porang glucomannan inhibited the growth of Escherichia coli, enhanced the production of total SCFA, and reduced pH value of cecal content. The study indicated that glucomannan from porang may be used as functional food.