Grain Processing Corporation
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how we make alcohol

Corn Kernel Structure GPC produces pure ethyl alcohol using only No. 2 yellow dent corn. The first step in the process is steeping the corn in a mild acidic water solution. This helps to prepare the corn for separation into its component parts; corn oil, corn fiber, corn gluten and corn starch.

Then the corn is wet milled, and through a series of processes, separated into its various components. Unmodified pearl starch is cooked at an elevated temperature, swelling the surface area to make it open to enzymatic action. Alpha amylase is first added to cut the carbohydrate chain to dextrins; then gluco-alpha amylase is added to cleave individual glucose molecules from the dextrin chain. The terms “glucose” and “dextrose” are one and the same.

The glucose is then transferred to fermentation tanks where yeast is added to convert the sugar to ethanol and CO2. The resulting mixture is processed through a minimum of four distillation steps that remove impurities produced by the yeast, resulting in highly refined, potable ethyl alcohol. To make anhydrous alcohol, we process the 191+ proof alcohol through a vapor phase molecular sieve, which results in very low moisture anhydrous ethanol.

GPC’s pure ethyl alcohols are produced at its two corn wet milling plants in Muscatine, Iowa, and Washington, Indiana. The ethyl alcohols are made under sanitary conditions, using good manufacturing processes and procedures. GPC has high purity alcohol for use in pharmaceutical applications. We are inspected periodically to determine that we have quality systems in place. GPC meets all local, state and federal health regulations and produces ethyl alcohol that meets United States Pharmacopeia and Food Chemical Codex specifications for food grade material.

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alcohol news

  • 3.1.2021
    Grain Processing Opens Large, High-Quality, Efficient Distillery
    [read more]
  • 12.15.2016
    Grain Processing Corporation receives Energy Efficiency award at 4th Annual Iowa Association of Municipal Utilities Conference
    [read more]
  • 5.19.2015
    GPC Announces Major Alcohol Expansion in Muscatine Iowa
    [read more]
  • 5.19.2015
    GPC Anuncia Proyecto de Expansión Mayor en su Capacidad de Producción de Alcohol en Muscatine Iowa
    [read more]
  • 5.7.2015
    GPC's New Dryer House is Operational
    [read more]
  • 4.2.2014
    Grain Processing Corporation Awarded Lab Accreditation
    [read more]
  • 5.5.2010
    Liquor Dealer Recordkeeping and Registration and Repeal of certain Special Occupational Taxes
    [read more]
  • 1.24.2003
    New Agency Regulates Alcohol and Tobacco Laws
    [read more]