Colloidal Properties of the Residue of Rice Wine made from Thai Purpleberry 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 Thai glutinous rice, upcycling the rice wine residue (RWR) into a value-added ingredient. This study aims to identify the colloidal properties of RWR and exploring 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 fermentation was accelerated due to ultrasound with 30 v.% alcohol yielded within 3 weeks of fermentation.  The fine particulates obtained from the clarification of RWR were characterized via Mastersizer and resulted in bimodal distribution with sizes of 0.12 and 27 μm. The surface net charge of these particles measured via Zetasizer was found to be around -7.8 ±0.5 mV. RWR at 0.5 wt.% was able 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.