Products and By-Products of Corn Wet
Milling
Corn (Zea mays) is one of the most versatile cereal grains globally,
processed for a wide range of food, feed, and industrial products. The
wet milling process is primarily used to separate the corn kernel into its
major chemical components — starch, protein (gluten), fiber, and
germ — each having significant industrial value.
Unlike dry milling, which mainly produces grits, meal, and flour, wet
milling is a biochemical and mechanical process involving steeping,
grinding, and fractionation of the kernel into purified fractions that form
the base for starch, sweeteners, oil, and fermentation industries.
Objectives of Corn Wet Milling
● To efficiently separate and recover corn kernel components in pure
form.
● To produce high-quality starch, sweeteners, oil, and
gluten-based feed.
● To maximize the yield of economically valuable by-products and
minimize losses.
Basic Steps in Corn Wet Milling
1. Cleaning and Steeping:
Cleaned corn is soaked in warm water (50°C) containing
0.1–0.2% sulfur dioxide for 30–48 hours. This softens the kernel,
loosens the gluten-starch matrix, and prevents microbial growth.
2. Degermination:
The softened kernels are coarse-ground to free the germ from the
endosperm. Germ is separated by centrifugation due to its lower
density.
, 3. Grinding and Screening:
The remaining slurry is finely ground to release starch and gluten
from the fiber. Sieves and hydrocyclones separate fiber.
4. Starch-Gluten Separation:
Centrifugal separators or hydrocyclones are used to isolate
starch (heavier) and gluten (lighter) fractions.
5. Product Drying and Refinement:
Separated starch is dried, modified, or converted enzymatically for
further processing into various products.
Major Products of Corn Wet Milling
a) Corn Starch
● Description: The principal product of wet milling, accounting for
about 60% of kernel weight.
● Processing: After gluten separation, starch is washed and refined
to >99% purity.
● Uses:
○ Food industry: Thickener, stabilizer, and texturizer in soups,
sauces, and puddings.
○ Industrial use: Paper coating, adhesives, textiles, and
bioplastics.
○ Converted products: Dextrins, glucose, and maltodextrins.
b) Corn Syrup
● Description: Produced by partial enzymatic hydrolysis of corn
starch using α-amylase and glucoamylase.
● Composition: Contains glucose, maltose, and dextrins.
● Uses: Sweetener in confectionery, bakery, beverages, and canned
goods.
Milling
Corn (Zea mays) is one of the most versatile cereal grains globally,
processed for a wide range of food, feed, and industrial products. The
wet milling process is primarily used to separate the corn kernel into its
major chemical components — starch, protein (gluten), fiber, and
germ — each having significant industrial value.
Unlike dry milling, which mainly produces grits, meal, and flour, wet
milling is a biochemical and mechanical process involving steeping,
grinding, and fractionation of the kernel into purified fractions that form
the base for starch, sweeteners, oil, and fermentation industries.
Objectives of Corn Wet Milling
● To efficiently separate and recover corn kernel components in pure
form.
● To produce high-quality starch, sweeteners, oil, and
gluten-based feed.
● To maximize the yield of economically valuable by-products and
minimize losses.
Basic Steps in Corn Wet Milling
1. Cleaning and Steeping:
Cleaned corn is soaked in warm water (50°C) containing
0.1–0.2% sulfur dioxide for 30–48 hours. This softens the kernel,
loosens the gluten-starch matrix, and prevents microbial growth.
2. Degermination:
The softened kernels are coarse-ground to free the germ from the
endosperm. Germ is separated by centrifugation due to its lower
density.
, 3. Grinding and Screening:
The remaining slurry is finely ground to release starch and gluten
from the fiber. Sieves and hydrocyclones separate fiber.
4. Starch-Gluten Separation:
Centrifugal separators or hydrocyclones are used to isolate
starch (heavier) and gluten (lighter) fractions.
5. Product Drying and Refinement:
Separated starch is dried, modified, or converted enzymatically for
further processing into various products.
Major Products of Corn Wet Milling
a) Corn Starch
● Description: The principal product of wet milling, accounting for
about 60% of kernel weight.
● Processing: After gluten separation, starch is washed and refined
to >99% purity.
● Uses:
○ Food industry: Thickener, stabilizer, and texturizer in soups,
sauces, and puddings.
○ Industrial use: Paper coating, adhesives, textiles, and
bioplastics.
○ Converted products: Dextrins, glucose, and maltodextrins.
b) Corn Syrup
● Description: Produced by partial enzymatic hydrolysis of corn
starch using α-amylase and glucoamylase.
● Composition: Contains glucose, maltose, and dextrins.
● Uses: Sweetener in confectionery, bakery, beverages, and canned
goods.
