Sediments in concentrated green tea during low-temperature storage.

Area of Science:

• Food Chemistry
• Beverage Science
• Material Science

Background:

• Sediment formation in concentrated green tea beverages during storage is a common issue.
• Understanding the composition and formation dynamics of these sediments is crucial for product quality and stability.

Purpose of the Study:

• To investigate the formation timeline and chemical composition of reversible tea sediments (RTS) and irreversible tea sediments (IRS).
• To identify the key components contributing to sediment formation in green tea concentrates during low-temperature storage.

Main Methods:

• Concentrated green tea samples were stored at low temperatures.
• Sediment formation was monitored over time (up to 80 days).
• Chemical analysis was performed to determine the composition of RTS and IRS, including mineral content and solubility.

Main Results:

• RTS formed primarily within the first 10 days, constituting over 90% of total sediment and composed of polyphenols, sugars, caffeine, flavones, and proteins.
• IRS formation occurred between 20 and 40 days, with significantly higher mineral content (17.1% vs. 2.6% for RTS).
• IRS primarily consisted of calcium, magnesium, gallium, and manganese oxalates, with 75% soluble in 0.1 M HCl, largely due to oxalate content (68%).

Conclusions:

• Minerals and oxalic acid are critical factors driving the formation of irreversible tea sediments (IRS).
• The distinct chemical compositions of RTS and IRS highlight different degradation and precipitation pathways during storage.