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

Sensory Testing

Sensory Testing
Sensory testing utilizes one or more of the five senses to evaluate foods.

Taste panels, comprising groups of people, taste specific food samples under controlled conditions and evaluate them in different ways depending on the particular sensory test being conducted.

This is the only type of testing that can measure consumer preference and acceptability.

When it comes to public opinion of a product, there is no substitute for tasting by individual consumers.

In addition to a taste –panel evaluation, objective tests can be established that correlate with sensory testing, which give an indication of consumer acceptability, but this may not always be sufficient.

In the development of new foods or when changing an existing product, it is necessary to determine consumer acceptance directly and objective testing is not sufficient, even though it may be a reliable, objective indication of food quality.

Sensory methods may be used to determine:
*Whether foods differ in taste, odor, juiciness, tenderness, texture and so on.
*To what extend food differ
*To ascertain consumer preferences and to determine whether a certain food is acceptable to a specific consumer group.

Three types of sensory testing are commonly used, each with different goal. Discrimination or difference tests are design to determine whether there is a difference between products, descriptive tests determine the extent of difference in specific sensory characteristics and affective or acceptance/preference tests determine how well the products are liked or which products are preferred.

There are important differences between these types of tests. It is important to select the appropriate type of test so that the results obtained are able to answer the question being asked about the products and are useful to the manufacturer or product developer.

The appropriate tests must be used under suitable conditions in order for results to be interpreted correctly.

All testing must be carried out under controlled conditions, with controlled lighting, sound (no noise), and temperature to minimize distractions and other adverse psychological factors.
Sensory Testing

Butter

Butter
Butter is one of the main fat products used as spreads. Both of these products are water in oil emulsions.

Butter usually contains about 80% fat. In England, butter must not contain more than 16% water.

Other constituents of butter include protein (1%), lactose (0.4%), mill ash (0.15%), and salt.

The natural color of butter is due to carotene and other fat soluble pigments.

The major proportion of the butter consumed in many countries is sweet cream butter. That is butter manufactured from fresh cream.

Lactic butter, which is more popular is some other countries is manufactured from cream which is first cultured to develop aromatic flavored compounds, e.g. diacetyl.

Both types of butter may be slated (up to 2% salt) depending on market requirements.

Production
Butter making is synonymous with churning of cream in batch or in continuous buttermakers, the latter having been established since the 1930s.

While both processes have been optimized over the years, batch churns are mainly used in smaller dairies and cheese factories (where the cream recovered from whey is churned into whey butter)and continuous plants are used in large scale operations productions 1 – 4 ton of butter.
Butter

Taste Sensitivity

Taste Sensitivity
People vary in their sensitivity to different tastes. Sensitivity depends on the length of time allowed to taste a substance.

Sweet and slat tastes are detected quickly (in less than a second), because they are detected by taste buds in the tip of the tongue, in addition, they are usually very soluble compounds.

Bitter compounds, on the other hand may take a full second to be detected because they are detected at the back of the tongue.

The taste may linger, producing a bitter aftertaste.

Sensitivity to a particular taste also depends on the concentration of the substance responsible for the taste.

The threshold concentration is defined as the concentration required for identification of a particular substance.

The threshold concentration may vary from person to a person: some people are more sensitive to a particular taste than others and therefore are able to detect it at a lower concentration.

Below a threshold concentration, a substance would not be identified but may affect the perception of another taste.

For example subthreshold salt levels increase perceived sweetness and decrease perceived acidity, whereas subthreshold sugar concentrations make a food taste less salty than it actually is.

Although it is not clear why, flavor enhancers such as MSG also affect taste sensitivity by intensifying a particular taste in a food.

Temperature of food also affects its flavor. Warm foods generally taste stronger and sweeter than cold foods. For example, melted ice cream tastes much sweeter than frozen ice cream.

There are two reasons for the effects of temperature on flavor. The volatility of substance is increased at higher temperatures, and so they smell stronger.

Taste bud receptivity also is an important factor. Taste buds are most receptive in the region between 68 and 86 degree F and so taste will be more intense in this temperature range.

Psychological factor also affect taste sensitivity and perception. Judgments about flavor are often influenced by preconceived ideas based on the appearance of the food or on previous experience with a similar food.

For example, strawberry flavored foods would be expected to be red. However, if colored green, because of the association of green foods with flavors such as lime, it would be difficult to identify the flavor as strawberry unless it was very strong.

Color intensity also affects flavor perception. A stronger color may also cause perception of a stronger flavor in a product, even of the stronger color is simply due to the addition of more food coloring.

Texture also can be misleading. A thicker product may be perceived as tasting richer or stronger simply because it is thicker and not because the thickening agent affects the flavor of the food.

Other psychological factors that may come into play when making judgments about the flavor of foods include time of day (for example, certain tastes are preferred at breakfast time), general sense of well being, health and previous reactions to a particular food or taste.
Taste Sensitivity