Cereal Grains Overview

Cereal Grains

• Cereal grains are seeds from grasses in the Poaceae family.
• They are a major source of calories globally, comprising about 50% of dietary energy.
• Major crops include wheat, rice, corn (maize), and barley.
• World grain production is distributed as follows: corn (32%), rice (29%), and wheat (28%).
• Consumption patterns vary between developing, industrial, and transition countries.

Cereal Grain Structure

• Kernels (or grains) have a similar structure.
• Husk/chaff: protects from extreme temperatures, insects, and other factors; not usually edible.
• Bran (糠): protective outer layer, excellent source of fiber and minerals; contains protein, phosphorus, thiamine, and other B vitamins and some fat.
• Aleurone layer: layer in the bran; removes it from white flour ; contains some vitamins and fat.
• Endosperm: largest part, primary source of carbohydrates (starch); contains protein, some vitamins, and certain minerals.
• Germ: at base of kernel; rich in fat, incomplete proteins, vitamins and minerals (especially vitamin B and E); easily goes bad if not refrigerated.

Cereal Grain Nutrients

• Carbohydrates: excellent source of complex carbohydrates.
• Fiber: good sources of soluble and insoluble fiber, especially in whole grains.
• Fat: very low fat content in refined grains; may have added back in some types.
• Vitamins and minerals: some vitamins and minerals are lost during processing; can be replaced through enrichment.
• Protein: incomplete protein in most grains; often complemented by other protein sources

Cereal Growth and Harvesting

• Annual crops, usually one growing season per year.
• Harvesting methods: cutting, threshing, and winnowing (removing chaff).
• Different growing conditions for winter (cool/cold) and summer (warm/hot) grains.
• Rice: grown with roots submerged in water (lowland rice) or in areas with plentiful rain (dry rice).

Rice Types and Processing

• Brown rice: only husk is removed.
• White rice: bran and germ are removed.
• Enriched rice: nutrients (fiber, vitamins, iron, etc.) removed during processing are added back.
• Converted rice: rice is soaked, steamed, and dried before milling, resulting in higher nutritional value.

Wheat Flour Types

• Several types of wheat flour, including whole grain flour, made from whole grains.
• Different varieties of wheat are used to produce different types of flour (hard, soft).
• Flour composition varies by the protein content in the various types.

Wheat Flour Composition

• Flour is typically composed of starch, gluten protein (contributes to texture); other ingredients can be added to flour mixtures.
• Gluten formation is triggered by hydration; when kneaded, this results in elasticity, strength, and smooth texture in dough.
• The rise in dough occurs as gas (steam, air etc.) expands. Heat during baking helps further expand gluten.
• Different leavening agents (including yeast) are used to enhance rising.

Pasta

• Pasta is primarily made from semolina and/or farina.
• Can also be made from whole wheat, with slight differences in nutritional content and texture.
• Fresh pasta has a higher moisture content, softer consistency, and shorter shelf-life.
• Dried pasta (extruded) is prepared with lower moisture content (10% - 12%) to last longer.; heat treating can cause protein denaturing.