Food processing: Malting

Malting is the limited germination of cereal grains or occasionally, the seeds of pulses (peas and beans), under controlled conditions. The starting and stopping of botanical growth is expertly timed by the maltster to achieve a minimum malting loss and maximum malt modification.

Sometime malt is used ‘green’ (undried), but it is usually used after drying in the sum or in a current of warm water. The three main steps of the malting process are steeping, germination and kilning. Final stage of malting process is kilning, enzyme activities decline as malt color and malt flavor develop.

This converts the endosperm of the grain into simple sugars which later be partially converted by fermentation into alcohol.

In the industrialized regions of the world, malt made from barley is by far the most important, but malts are, or have been, made from wheat, rye, oats, triticale, maize, sorghum, various millets and even rice.
Food processing: Malting

What is quick cooking rice?

Pregelatinized and packaged rice without excess drying has been developed in Japan. This type of rice is popular because of their short cooking time, instant and quick-cooking rice are partially or fully cooked before they are packaged.

This form of rice is widely available and only takes a few minutes to prepare by rehydrating and heating; it is widely used for its conveniences.  Consumers only have to add the tasty cooking soup or water and cook for about 15 minutes. Cooking time of both brown and white rice is shortened by heating the dry grains in a current of air at elevated temperatures.

The kernels are so modified by fissuring of the surface layers, by dextrinization, and in the case of brown rice, by loosening of the bran layers, that the cooking time in the home is reduced to about one-third that of raw rice.

Compare with instant rice; quick cooking rice is improved in terms of taste and texture. After cooking, the product should match the characteristics favor, taste and texture of conventionally cooked rice.

The product should be packaged properly in plastic film bags of special design against moisture changes during storage.
What is quick cooking rice?

Defects and impurities of wheat

During harvesting and postharvest handling and storage of wheat at the farm, it becomes exposed to a wide range of foreign matter comprised of various types of seeds such as oats, barley, wild oats, corn, pea, flax, rapeseed, mustard, wild buckwheat and such.

In remote areas certain countries high levels of impurities such as sand or dust result from manual harvesting,

Quality attribute are measured using a multitude of specific tests designed or provide information on the various characteristics of grain.

These include the measurement for conditions such as kernel density; moisture; damage, broken or split kernels; impurities and other visual defects.

Wheat and other cereal grains are subject to government inspection and grading. In establishing the grain grades for wheat, certain defects and impurities in wheat have been identified as definitely affecting the yield and quality of the wheat.

With a proper grading system in place, as in major grain-exporting countries, tolerance level for all the factors listed as part of the grading factors is established. The grade-determining factors should be those that relate to sanitary quality purity, and soundness (absence of imperfections).

Consequently, it is important to consider some of the causes of these defects and their effect on the quality of wheat.
Defects and impurities of wheat

Field Corn

Corn (Zea mays L.) or maize, as it is known in Europe and other part of the world originated in the western hemisphere. In the United States, most corn is field corn. A kernel of field corn consists of 66 percent starch 2-4 percent oil and the reminder mainly cellulosic material.

Although it is now grown around the world, production of field corn in the United States exceeds in any other country and is usually about equal to that of the rest of the world put together. Field corn is primarily used for animal feed.

Currently, less than 10 percent of the United States field corn is used for direct domestic human consumption in corn based foods such as corn meal, corn starch and corn flakes, while the remainder is used for animal feed, exports, ethanol production, seeds, and industrial uses.

Field corn is entirely different as a food crop from the sweet corn that is harvested immature in summer and cooked fresh on the cob or cut from the cob in food plants and preserved by canning or freezing later consumer us as a vegetable.

Field corn is allowed to mature before harvest in the fall. It is shelled as a part of the harvesting operation and typically requires drying on the farm before storage or delivery to country elevator, grain terminal, or mill.

There are two basic strains of field corn, Flint and Dent. Flint corn is the hardier and harder of the two and has less starch. Dent corn is softer and is the variety that is usually grown for flour.

A very small part of the field corn crops of white corn varieties are used in foods as the chief ingredient in masa and lye hominy, while corn meal sold at retail, the grits being use as vegetable menu item or hot breakfast cereal, and the meal for making white corn bread and muffin.

Much field corn is used as feed for animals on the farm where it is grown but far larger amounts are manufactured into mixed feeds by formula feed manufacturers, feedlot operators and the like.
Field Corn

Wheat Structure

Wheat Structure
Wheat structure is a single seeded fruit, 4 to 10 mm long, consisting of a germ and endosperm enclosed by an epidermis and a seed coat.

The fruit coat or pericaprs (45 to 50 um thick) surrounds the seed and adhere closely to the seed coat.

The wheat color, depending on the species and other factors is red a to white and is due to material present in the seed coat.

Wheat also is classified based on physical characterizes such as red, white soft, hard spring or winter.

The outer pericaprs is consist of the epidermis and hypodermis. The epidermis consists of a single layer of cells that from the outer surface of the kernel.

On the outer walls of the epidermal cells is the water impervious cuticle. Some epidermal cells at the apex of the kernel are modified to form hairs.

The hypodermis is composed of one to two layers of cells. The inner pericaprs is composed of intermediate cells and cross –cells inward from hypodermis.

Long and cylindrical tube cells constitute the inner epidermis of the pericaprs. In the crease, the seed coat joins the pigment strand, and together they form a complete coat about the endosperm and germ.

Three layers can be distinguished in the seed coat: a thick outer cuticle, a “color layer” that contains pigment, and a very thin inner cuticle.

The bran comprises all outer structures of the kernel inward to, and including the aleurone layer.

This layer is the outer layer of the endosperm, but is considered as part of the bran by millers.

The aleurone layer is usually one cell thick and almost completely surrounds the kernel over the starchy endosperm and germ.

The endosperm is composed of peripheral, prismatic and central cells that are different in shape, size and position within the kernel.

The endosperm cells are packed with starch granules, which lie embedded in a matrix that is largely protein.
Wheat Structure

Cereal in general

Cereal in general
Cereals are monocotyledonous plants that belong to the grass family. Based on botanists’ approximation, there are about 350,000 plant species, of which about 195,000 species are economically important flowering plants.

Nearly 50 species are cultivated worldwide and as few as 17 species provide 90% of human food supply and occupy about 75% of the total tilled land on earth.

They consist of wheat, rice, corn, potato, barley, sweet potato, cassava, soybean, oat, sorghum, millet, rye, peanut, field bean, pea, banana and coconut.

The cereal grains such as wheat, rice, corn, barley, oat, rye, sorghum and millet provide 50% of the food energy and 50% of the protein consumed on earth.

Wheat, rice and corn together make up three-fourths of the world's grain production.

In general, cereal grain have been considered as the source of carbohydrates to supply food energy to the diet. Cereal grains, especially rice and wheat, provide the bulk of energy consumed on earth.

The cereal crops that are grown for their edible fruit are generally called grain, but botanically referred to as caryopsis. The cereal seed consist of two major components, the endosperm and embryo or germ.

The endosperm encompass the bulk of the seed and is the energy source of stored food.

An outer wall called the pericarp that develops from the ovary wall encases the endosperm. A semi-permeable layer under the epicarp, which is called testa, surrounds the embryo and is derived from the inner ovary wall.

The testa is permeable to water but not to dissolved salts an is important for germination. The third layer, which is called aleurone, contains thick walled cells that are free of starch. The pericarp, testa and aleurone layer are collectively called the bran.
Cereal in general

Composition of Cereal Grains

Composition of Cereal Grains
In composition, grains are structurally similar as seen; however, they vary in their nutrient composition, containing varying amounts of carbohydrate, fat, protein, water, vitamins and minerals.

The main nutrient component of cereal grains is carbohydrate which makes up 79-83% of the dry matter of grain.

It exists predominantly as starch, with fiber especially cellulose and hemicellulose, composing approximately 6% of the grain.

Lipid (fats and oil) makes up approximately 1-7% of a kernel, depending on the grain. For example, wheat rice, corn, rye and barley contain 1-2% lipid, oats contain 4-7%. The lipid is 72-85% unsaturated fatty acids, primarily, oleic acid and linoleic acid.

Protein composes 7-14% of the grain, depending on the grain. Cereals are low in the amino acids tryptophan and methionine, and although potential breeding may produce cereals higher in the amino acid lysine, it remains the limiting amino acid in cereals.

Grain consumption provides half of the protein consumed worldwide. However, in comparison to foods such as milk, meats or eggs, grains do not include all the essential amino acid contained in animal protein.

The protein is of low biological value and therefore, less efficient in supporting body needs.

Combining food sources of protein is common in cultures throughout the world.

The preparation of traditional dishes combines the lower biological value grains with legumes or nuts and seeds to provide the needed amino acids to yield a complete dietary protein.

For example a combination of beans with rice, or beans with cornbread, tofu and vegetables, or tofu and cashews, chickpeas and sesame seed paste (tahini) known as hummus, peanut butter on whole wheat bread and so forth are combinations creating complete proteins.

Vitamins present in cereals are predominantly the B vitamins-thiamin (B1), riboflavin (B2) and niacin (B3). These vitamins may be lost in the milling process and so are added back through the process of enrichment.

Whole grain products contain some fat soluble vitamins in the germ.

Water is present in cereal grains at levels of 10-14% of the grain. Of course soaking and cooking add water to cereal grains, and the grain size expands as additional water is absorbed.

If flour is high in protein content, it absorbs a lot of water compared to low protein flour.

Mineral are naturally present at higher levels in whole grains than in refined grains. Fortification of refined flour with added iron is common.

Zinc, calcium as well as vitamins also may be added at levels beyond not present in the original grain.

Fiber content is determined by different analysis and includes crude fiber (CF) and total dietary fiber (TDF).

These two measurements are not correlated. Crude fiber is composed of cellulose and the non-carbohydrate lignin. TDF includes cellulose and lignin, plus hemicellulose, pectic substances, gums and mucilages.
Composition of Cereal Grains