Abstract

Five different packaging treatments were studied over a 36‐day period to determine if they protected soymilk from photo‐oxidation. Soymilk was packaged in high‐density polyethylene ( HDPE ) bottles with and without light protective additives ( LPA ). Two controls [(1) no LPA (translucent appearance); (2) a light‐protected control (foil overwrap over no LPA control)] and three LPA ‐containing treatments, Low (0.6% TiO₂), Medium (1.3% TiO₂), High (4.3% TiO₂) were studied. Bottles were stored in a lighted refrigerated display case (average light intensity between 800 to 2200 lux; 3°C) for 36 days and evaluated weekly. Soymilk packaged in high LPA bottles was protected from developing light‐oxidized off‐flavors and odors for a minimum of 15 days. High LPA bottles provided protection for riboflavin and controlled development of photooxidative products for approximately 29 days.

This research demonstrates that light‐sensitive components in soymilk can be protected for a minimum of 15 days with packaging other than paperboard. Titanium dioxide as a light protective additive applied to high‐density polyethylene can improve protection of light‐sensitive compounds. As sensory quality deteriorated before riboflavin degradation and photooxidative changes suggests that other aspects of soymilk contribute to decline in flavor quality over time rather than just lipid oxidation.