Colloidal Properties of the Rice Wine Residue of Thai Purple Rice and its Effects as a Stabilising Agent in Foams

Abstract

Research toward food waste valorisation has been an attractive subject and aligned with the UN’s Sustainable Development Goal (SDG) 12.3 aiming at drastic reduction of the ecological footprint via minimizing food losses by 2030. In this context, we draw our research focused on upcycling the rice wine residue (RWR) into a value-added ingredient. This study aimed to identify the colloidal properties of RWR and explore its potential application as a stabilising agent for foams or bubbles. Ultrasound treatment was employed at 20 kHz for 30 minutes to breakdown the rice grain and refine the particulates into smaller sizes. The particle sizes of RWR were characterized via Mastersizer and resulted in bimodal distribution with sizes of 0.12 and 27 μm. The surface net charge was found to be around -7.8 ±0.5 mV as measured via Zetasizer. The residue was dried and incorporated into a model foam system using 0.5 wt.% sodium caseinate to initiate the bubble formation. RWR at 0.5 wt.% has shown its ability to retain a stable foam over time for more than 6 hours. To conclude, RWR may potentially be deemed as a foam stabiliser via Pickering stabilization at the bubble interface.

Keywords

• rice wine residue
• thai purple berry rice
• stabilizing agent
• foam