Cereals and grains lecture note

Introduction to Cereals

• Cereals are grains and specific types of grains that are seeds of grass plants.

  • Most common cereals in the U.S.:

  • Wheat

  • Oats

  • Rice

  • Corn

• Cereals are staple foods globally, varying by region:

  • Wheat is the main staple in the U.S.

  • Rice predominates in Asia.

  • Corn is common in Central America.

• Lecture Overview:

  • Structure and composition of cereal grains.

  • Common processing procedures.

  • Specific cereal products popular in the U.S.

  • Discussion on wheat flour and wheat flour doughs in current or subsequent lectures.

Structure of Cereal Grains

• Parts of a Cereal Grain:

  • Bran:

  • Represents about 15% of the grain's weight.

  • Varies significantly among grain types and varieties.

  • High in cellulose, a good source of fiber, minerals, and some B vitamins.

  • Germ:

  • Approximately 2-3% by weight of the kernel.

  • High in fat and protein, contains vitamins and minerals.

  • Endosperm:

  • Comprises about 83% of the grain's weight.

  • Mainly composed of starch, with some protein.

  • Aleurone Layer:

  • One-cell thick layer separating the bran from the endosperm.

Composition of Cereal Grains

• General composition of cereal grains:

  • Carbohydrates: Approximate amounts vary; check specific grain for details.

  • Protein: Varies, typically highest in the germ.

  • Water: Present at various levels depending on the grain.

  • Fat: Lower in bran and endosperm, higher in germ.

Processing of Cereal Grains

• De-Hulling:

  • Removing the hulls post-harvest, essential as hulls are indigestible.

• Refining:

  • Involves removing the bran and germ.

  • Results in paler grains, traditionally viewed as more desirable.

  • Removes nutrients, leading to enriching (adding back vitamins, not minerals or fiber).

• Parboiling:

  • Involves steaming the grain before refining.

  • Nutrients from bran and germ migrate into the endosperm, benefiting the final product.

• Cooking of Grains:

  • Cooking makes grains palatable and easier to digest (softens bran and gelatinizes starch).

  • Water absorption can be several times the grain's original weight, impacting cooking time.

Specific Cereal Products in the U.S.

Corn

• Popcorn:

  • Moisture content must be around 11-14% for optimal popping.

  • The structure of the corn kernel traps steam until pressure builds, causing it to pop.

• Nixtamalization:

  • Corn kernels soaked in alkaline solutions (lime or ashes) for easier milling.

  • Breaks down hemicelluloses, makes the pericarp easier to grind, enhances nutrition (releases niacin).

• Forms of Corn:

  • Hominy: Whole kernels treated with alkaline.

  • Masa: Ground from nixtamalized corn.

  • Cornmeal and Grits: Dried and ground corn, differing in particle size.

Barley

• Primary use is for making malt by sprouting grains.

• Malt is high in amylase enzymes, crucial for converting starch to sugar for beer fermentation.

• Barley can also be used in whole grain forms for soups and stews.

• Pearl Barley: Refined barley with bran and germ removed.

Oats

• Most commonly consumed as oatmeal.

• Types of oatmeal include:

  • Steel Cut Oats: Whole grains cut into pieces, longer cooking time.

  • Rolled Oats (Regular): Steamed and flattened grains, quicker cooking time.

  • Quick Cooking Oatmeal: Smaller pieces of rolled oats for faster prep.

  • Instant Oatmeal: Pre-cooked, dried grains rehydrate quickly in boiling water.

• Oat Flour: Finely pulverized oats for baking.

Rice

• Brown Rice: Whole grain, retains bran and germ.

• White Rice: Refined grain, with potential enrichment (vitamins added, but not fiber or minerals).

• Converted Rice: Parboiled and thus retains nutrients, often yields better cooking results.

• Types of cooking rice include:

  • Quick Cooking Rice: Pre-cooked and dried.

  • Instant Rice: Pre-cooked and dried with phosphate salts for rapid hydration.

  • Wild Rice: Fermented post-harvest to develop flavor and color.

Wheat

• Mostly consumed in bread form, can also be used in whole grain soups and stews.

• Cracked Wheat: Whole grain cut into pieces.

• Farina: Refined wheat endosperm ground into chunks.

• Bulgur: Traditionally made from parboiled wheat, can be made from whole grain.

• Milling Process: Removes bran and germ; even whole wheat flour includes milled bran and germ.

• Flour Types:

  • Hard Flours: Higher in protein (10-14%), used for breads.

  • Soft Flours: Lower in protein (7-10%), ideal for pastries.

  • Semolina: Durum wheat flour used for pasta, provides chewy texture.

  • Bleached Flour: Contains oxidizing agents, affects gluten properties; alternatives include aging flour naturally.

Conclusion

• Understanding the diverse aspects of cereals, including their structure, processing, and forms can significantly enhance culinary practices and nutritional knowledge.