Modulation of the Chemical Properties, Photostability, and Antioxidant Activity of Turmeric Oleoresin by Propylene Glycol

Q: Why are curcuminoids from turmeric limited in practical food applications?

Their use is limited by poor stability and solubility, including susceptibility to degradation from light, heat, pressure, and alkaline pH, and their insolubility in aqueous systems.

Q: How does propylene glycol (PG) affect the solubility and dispersion stability of turmeric oleoresin?

PG significantly improved solubility and dispersion stability in aqueous solutions (P < 0.05).

Q: What is the impact of PG on the photostability and antioxidant activity of TO?

PG improved TO photostability in a concentration-dependent manner, extended its half-life under irradiation, increased retention of individual curcuminoids under light, and enhanced antioxidant properties by increasing reducing power in aqueous solutions.

Sep 29, 2026

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Curcuminoids from turmeric show beneficial health effects, yet limited practical use arises from poor stability and solubility. This study examined how propylene glycol (PG), a common food additive, modulates the chemical properties, photostability, and antioxidant activity of turmeric oleoresin (TO). PG significantly improved solubility and aqueous dispersion stability (P < 0.05). At 20–30% PG, pigment sedimentation was effectively prevented and pigment integrity was maintained. PG also enhanced photostability and increased curcuminoid retention under fluorescent and blue LED irradiation, while improving antioxidant reducing power in a concentration-dependent manner, supporting longer shelf life and preserved product quality.

LanguageEnglish

CategoryResearch & Report

FormatPDF

Pages8

Reading Time20 min

AccessFree to download

Introduction

Background on turmeric pigments and curcuminoids

Limitations: stability and solubility

Role and safety concerns of propylene glycol

Study aims and experimental approach

Prev. Nutr. Food Sci. 2025;30(6):599-606 [https://doi.org/10.3746/pnf.2025.30.6.599](https://doi.org/10.3746/pnf.2025.30.6.599)[ ](https://doi.org/10.3746/pnf.2025.30.6.599)[ISSN 2287-8602](ISSN 2287-8602) Modulation of the Chemical Properties, Photostability, and Antioxidant Activity of Turmeric Oleoresin by Propylene Glycol Yunkyung Sung and Jungil Hong Department of Food Science and Technology, College of Science and Convergence Technology, Seoul Women’s University, Seoul 01797, Korea ABSTRACT: Curcuminoids from turmeric exhibit beneficial health effects. However, their practical application is limited because of poor stability and solubility. The present study investigated the effects of propylene glycol (PG), a common food additive, on the chemical properties, photostability, and antioxidant activity of turmeric oleoresin (TO). PG significantly improved the solubility and dispersion stability in aqueous solutions (P <0.05). PG at 20%－30% concentration effectively prevented pigment sedimentation and maintained pigment integrity similar to organic solvents. PG also improved the photostability of TO in a concentration-dependent manner, extending its half-life under irradiation with fluorescent light (FL) and blue light-emitting diode. The results of high-performance liquid chromatography analysis revealed that TO stored with PG in the dark or under FL irradiation had significantly higher retention of individual curcuminoids (P <0.05). In addition, PG conferred a concentration-dependent protective effect on the antioxidant properties of TO, increasing its reducing power in aqueous solutions. These findings suggest that incorporating optimal levels of PG can extend the shelf life of and preserve the quality of curcuminoid-containing products. Keywords: antioxidant activity, curcuminoid, photostability, propylene glycol, turmeric INTRODUCTION In the food industry, natural dietary pigments are widely used to provide visual appeal to products. The functional properties of these pigments have been extensively studied. Recently, the beneficial health effects of plant-based pigments have received considerable attention (Timberlake and Henry, 1986). Among them, pigments derived from turmeric (Curcuma longa L.) have been a major focus of research (Kocaadam and Şanlier, 2017). Turmeric pigments (also known as curcuminoids) are the primary yellow compounds in the turmeric rhizome. They include curcumin, demethoxycurcumin (DMC), and bis-demethoxycurcumin (BMC) (Priyadarsini, 2014). Turmeric oleoresin (TO) is a concentrated extract of turmeric rhizome that contains 30%－55% curcuminoids along with other volatile and fixed oils. TO is widely used as a spice, coloring agent, and functional ingredient in foods and supplements (Joshi et al., 2009). Curcuminoids are widely known for their diverse biological activities, including antioxidant, anti-inflammatory, antidementia, and anticancer effects (Masuda et al., 1999; Aggarwal et al., 2003; Gautam et al., 2007; Aggarwal and Sung, 2009). However, despite their high application potential, the practical application of curcuminoids is limited by their poor stability and solubility. Curcuminoids are particularly susceptible to degradation from light, heat, pressure, and alkaline pH (Jankun et al., 2016; Kharat et al., 2017; Jung and Hong, 2021). In addition, their insolubility in aqueous systems restricts their use in many food products (Tønnesen and Karlsen, 1985; Wang et al., 1997). Accordingly, extensive research has focused on improving the processing properties and bioavailability of curcuminoids (Sari et al., 2015). Propylene glycol (PG) is a common food additive that is used as an emulsifier, humectant, and stabilizer. It also enhances the solubility and dispersibility of various hydrophobic compounds in aqueous solutions (Okolie, 2022). It is widely used in cosmetics, pharmaceuticals, and food products and is generally recognized as safe by regulatory bodies worldwide, incl

FAQs

Why are curcuminoids from turmeric limited in practical food applications?

Their use is limited by poor stability and solubility, including susceptibility to degradation from light, heat, pressure, and alkaline pH, and their insolubility in aqueous systems.

How does propylene glycol (PG) affect the solubility and dispersion stability of turmeric oleoresin?

PG significantly improved solubility and dispersion stability in aqueous solutions (P < 0.05).

What is the impact of PG on the photostability and antioxidant activity of TO?

PG improved TO photostability in a concentration-dependent manner, extended its half-life under irradiation, increased retention of individual curcuminoids under light, and enhanced antioxidant properties by increasing reducing power in aqueous solutions.

Sep 29, 2026

Upload by ahduag