# Impact of Bottle Type and Gelatin-Based Film Strips with Ethyl Sinapate on Oxidative Status and Antioxidant Properties of Cold-Pressed Rapeseed Oil

## TL;DR

This study shows that using gelatin-based films with ethyl sinapate and dark glass bottles can help preserve cold-pressed rapeseed oil by reducing oxidation and extending its shelf life.

## Contribution

The novel use of ethyl sinapate-infused gelatin films combined with specific bottle types to enhance the antioxidant properties and shelf life of cold-pressed rapeseed oil is presented.

## Key findings

- Gelatin-based films enriched with ethyl sinapate significantly increased antioxidant activity and total phenolic content in stored rapeseed oil.
- Using dark glass bottles reduced oxidation and preserved oil quality better than clear bottles.
- The combination of GPE films and dark bottles effectively inhibited both primary and secondary oxidation products during storage.

## Abstract

Cold-pressed rapeseed oil aligns well with the trend of growing demand for minimally processed, health-promoting food products. It is essential to identify suitable storage conditions that protect cold-pressed rapeseed oil from oxidation, thereby extending its shelf life. In this study, the effect of gelatin/polyvinyl alcohol film strips enriched with ethyl sinapate (GPE) and immersed in cold-pressed rapeseed oil samples was evaluated during an accelerated storage test (14 days at 40 ± 1 °C under light (power of luminous flux = 385 lm). The influence of bottle type differing in shape (Marasca and Dorica) and glass colour (amber and clear) was also assessed. The incorporation of GPE into the stored oils enhanced their antioxidant activity (AA) determined by 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid (ABTS = 1956.78–2334.10 µmol Trolox (TE)/100 g), 2,2-diphenyl-1-picrylhydrazyl (DPPH = 528.29–691.19 µmol TE/100 g), ferric reducing antioxidant power methods (FRAP = 454.14–511.61 µmol TE/100 g) and total phenolic content (TPC = 41.62–47.25 mg sinapic acid (SA)/100 g) compared to oils without film strips (ABTS = 1217.89 –1422.80 µmol TE/100 g, DPPH = 376.85–464.13 µmol TE/100 g, FRAP = 98.28–126.40 µmol TE/100 g and TPC = 6.38–8.02 mg SA/100 g) after first week of storage and confirmed the effective gradual release of ethyl sinapate from films to oils during two weeks of accelerated storage (ABTS = 2064.80–3086.47 µmol TE/100 g, DPPH = 597.11–854.37 µmol TE/100 g, FRAP =428.00–599.76 µmol TE/100 g, and TPC = 35.02–57.19 mg SA/100 g). Moreover, the GPE inhibited oil deterioration by reducing both primary (peroxide value (PV) = 3.75–5.11 meq O2/kg and 3.64–4.89 meq O2/kg, K232 = 1.236–1.494 and 1.551–1.675 after the first and second week of storage, respectively) and secondary oxidation products (anisidine value (pAnV) = 1.03–1.16 and 1.08–1.61; K268 = 0.102–0.170 and 0.185–0.237 after the first and second week of storage, respectively) compared to oxidative status of oils without film strips (PV = 3.76–5.59 meq O2/kg, K232 = 1.452–1.828, pAnV = 0.85–2.27, K268 = 0.154–0.263). In addition, synchronous fluorescence spectroscopy was applied to monitor changes in the main fluorescent components of the studied oils. Overall, the use of a dark glass bottle combined with antioxidant film strips proved to be an effective strategy for prolonging the shelf life of cold-pressed rapeseed oil.