Entrapment of 5‐aminolevulinic acid under edible composite film of konjac glucomannan and chitosan

Abstract

Entrapment of 5-aminolevulinic acid under edible composite film of konjac glucomannan and chitosan5-Aminolevulinic acid (5-ALA) is a known plant regulator and growth promoter. It is a very sensitive and highly unstable compound that is easy to deteriorate. Here we propose a novel approach to stabilize 5-ALA into a film. Films from konjac glucomannan (KGM), KGM treated with alkali solution (KGOH), chitosan (CHI) as well as blends between KGOH and CHI were fabricated for 5-ALA entrapment. It was found that the efficiency of KGM film, KGOH film and CHI film for 5-ALA entrapment was 55.7 ± 0.73%, 58.3 ± 0.36% and 60.3 ± 0.18 %, respectively. A 25:75 (%w/w) blended film (KGOH/CHI) showed the highest entrapment efficiency of 5-ALA (65.9 ± 0.37%) versus other films. The possible mechanism for entrapment of 5-ALA in blended film was postulated under two mechanisms. A secondary amide that leads to the interaction between the amino group of CHI and carboxyl group of 5-ALA is proposed as the first mechanism. The fact that the 5-ALA molecule was entrapped within the complexity of KGOH structure is proposed as the second mechanism. Therefore, stabilizing 5-ALA in a film may be an alternative way to use and preserve 5-ALA for further applications. able herbicide but acts as an insecticide when used at high concentrations [5]. Moreover, 5-ALA has attracted attention for use in medicine since it destroys malignant cells in photodynamic diagnosis and therapy [6]. 5-ALA is safe for using in food, cosmetics, medicine and agricultural purposes. However, the stability of 5-ALA in aqueous solution is a critical problem for its use in various fields. Stability of 5-ALA depends on pH, concentration, temperature and degree of oxygenation [1]. The degradation mechanism of 5-ALA under alkaline conditions occurs when two molecules of 5-ALA are condensed with a nucleophilic attack by a lone pair of the amino group of 5-ALA to a γ-carbonyl of another 5-ALA molecule to form 3, 6-dihydropyrazine 2,5-dipropionic acid (DHPY). The DHPY is then oxidized to pyrazine 2, 5-diproipionic acid (PY) under aerobic conditions [7]. An aqueous solution at lower pH values (<2) would be required to preserve the 5-ALA stability for long-term storage [8,9].Thus, the stability of the 5-ALA solution is a problem that still needs to be solved before it can become applicable in the industry. In addition, the zinc (II) ion can stabilize 5-ALA solution at neutral pH, however the process of forming zinc (II) complex is complicated [10]. The solid form of 5-ALA, known as 5-aminolevulinic acid hydrochloride, is more stable

Synbiotic edible film from konjac glucomannan composed of Lactobacillus casei‐01® and Orafti®GR, and its application as coating on bread buns

“…It is obvious that GR shifted the absorption bands of intermolecular hydrogen bond to a lower wavenumber, from 3337.01 to 3292.15 cm −1 in KGM/GR film and from 3308.21 to 3291.97 cm −1 in KGM/LC/GR film. Alteration in the spectra implied an interaction through intermolecular hydrogen bonds, which, in this case, occurred between KGM and GR.…”

“…Konjac glucomannan (Yunnan Gengyun Konjac Resources Developing Co Ltd, Kunming, China), with a molecular weight ranging from 200–2000 kDa, was used for preparing films. After KGM‐KOH mixture was prepared, the mixture was blended with LC and/or Orafti®GR (GR) (DPO (Thailand) Co., Ltd, Bangkok, Thailand), granulated chicory‐derived inulin in the form of a white soluble powder, to make four combinations of film‐forming solution (FFS) and coating coded as KGM, KGM/GR, KGM/LC and KGM/LC/GR. Viable probiotic cells in KGM/LC and KGM/LC/GR were adjusted to approximately 9 log colony‐forming units (CFU) mL −1 and 10 log CFU mL −1 in FFS and coating, respectively.…”

“…Cross-linking in synbiotic films was investigated using a Perki-nElmer Spectrum One Fourier transform infrared (FTIR) spectrometer connected to a Miracle Single-Reflection Diamond ATR device (PerkinElmer Inc., Waltham, Massachusetts, USA) over a wavelength range from 4000 to 400 cm −1 in transmission mode and using the KBr-pellet method. 2 Data were collected from 64 scans and the resolution was set to 4 cm −1 .…”

“…Konjac glucomannan (KGM), one of the most prominent compounds in the food and drug industry, is a water‐soluble dietary fiber with good film‐forming properties, health‐promoting functions, and capacity for compound entrapment. It is a well established functional food ingredient with prebiotic activity . Although many studies have attempted to use KGM as a carrier for unstable natural compounds, such as sweet basil oil, galangal extract, and 5‐aminolevulinic acids, the development of a synbiotic edible film from this biopolymer and research into its application on food products have not been attempted.…”

“…It is a well established functional food ingredient with prebiotic activity . Although many studies have attempted to use KGM as a carrier for unstable natural compounds, such as sweet basil oil, galangal extract, and 5‐aminolevulinic acids, the development of a synbiotic edible film from this biopolymer and research into its application on food products have not been attempted. Synbiotic edible film reduces limitations such as diet restrictions and stress‐processing methods.…”