US 4220673

Patent Overview: US 4,220,673 A

Title: Low-temperature steam desorbate process for improved instant tea
Patent number: US 4,220,673 A
Inventor: Rudolf G. K. Strobel
Assignee: Procter and Gamble Co (original and current assignee as listed)
Application number: US05/936,951
Priority/filing date: 1978-08-25
Publication (grant) date: 1980-09-02
Legal status (as listed): Expired – Lifetime; anticipated expiration 1998-08-25
Source: https://patents.google.com/patent/US4220673/en

Purpose. The patent addresses instant tea quality. Its stated objects are to upgrade taste and flavor of instant teas, provide a good-looking cup that tastes like freshly brewed tea but is less bitter and less astringent, and provide instants that are cold-water soluble with solution stability for iced tea beverages.

Plain-language scope. The process treats a bed of dry ground tea leaves. A small upper portion of the bed is pre-wetted and pre-swelled with steam (optionally with a little water) — the excerpt states this step is "critical." The bed is held under vacuum at low temperature (preferably below 55° C.) while water and steam are applied, and the desorbed aqueous tea extract is condensed in a cold trap, preferably trapping an aroma/flavor fraction as frost. Preferred embodiments include pre-wetting about 1–30% (most preferably 10–25%) of the bed; absolute pressure of about 13–400 mbar (more preferably 25–300 mbar); cold trap below about 10° C., more preferably below −60° C.; a draw-off ratio of about 0.9:1 to 2.5:1; and pulsed CO₂ during extraction to increase yields. The initial extract is dried to a stable cool-water-soluble instant tea. Cold hard-water solubility is said to be improved by process-water additives: higher-chain polyphosphates (e.g., Glass H® from FMC), sulfites/bisulfites (preferably sodium bisulfite), or low-calcium lambda-carrageenan. An apparatus with column, false bottom, retaining layer, nozzle system, and condenser inlet warmer is described.

What the excerpt does not establish. It does not report claim text, claim count, or claim scope; does not establish validity, enforceability, or freedom to operate; does not report litigation or ownership transfers; and gives no complete prior-art analysis — it mentions U.S. Pat. No. 4,004,038 (Wickremasinghe) and general sodium bisulfite use only. The excerpt is truncated, so some disclosure is missing.