What is the meaning of chemical hazards?

Chemical hazard are chemicals that can get into food by improper storage of chemical or chemical containers or by using chemicals improperly.

Generally, industrial pollutants are unintentional contaminants of foods,, even if regulated, may be difficult to control.

Some toxic chemical compounds can occur naturally in foods and in the environment.

Chemical hazards can cause food borne disease and the consumer health. This includes naturally occurring substances, such as allergens, and toxins and contamination of food with chemicals substance, their residue or their degradation products at levels that can harm the consumers.

Chemical hazards include:
• pesticides
• food additives and preservatives
• cleaning and sanitizing supplies
• toxic metals that leech through worn cookware and equipment
• lubricants used on equipment

The above chemicals must be approved by federal agency before they can be legally used. If a chemical leaves a residue in food, the cognizant agency is responsible for establishing a tolerance level – the amount of residue that can legally remain in or on raw and processed foods.
What is the meaning of chemical hazards?

Stress metabolites by plant

Plant under the stress by disease microorganisms produce stress metabolites, known as phytoalexins, which provide a natural defines.

Phytoalexins are usually elicited locally at the site of attack. Some evidence exists for accumulation of phytoalexins in edible tissue, particularly in potatoes and sweet potatoes.

Some phytoalexins have been demonstrated to be toxic to humans, but it is difficult at this time assess the potential toxicological implication of increased level of phytoalexins in human foods. 
Stress metabolites by plant

Chemical composition of fruit

Fruit quality ultimately depends on chemical composition. Composition of fruit not only vary according to botanical variety, cultivation practices, and weather, but also change with the degree of maturity prior to harvest the condition of ripeness and storage conditions.

In mature fresh fruit, there are many chemical constituents and enzyme systems functioning to carry on their physiological performance without interfering with or rejecting one another.

Most fresh fruits are high in water content and low in protein and fat. In these cases water contents will be greater than 70% and frequently greater than 85%.

However, when juice is extracted from the fruit by crushing, pressing, or reaming, constituent mixing occurs, which of uncontrolled, can lead to undesirable changes in flavor, color, aroma and stability.
Fruits are also important sources of both digestible and indigestible carbohydrates. The digestible carbohydrates are present largely in the form of sugars and starches while indigestible cellulose provides fibers that are important to normal digestion.

A substantial proportion of complex carbohydrates in fruits is present as dietary fiber in the form of cellulose, hemicellulose, pectic substances and lignin.

Fruits are also important sources of minerals and certain vitamins, especially vitamin A and C. Green and yellow fruits are rich source of vitamin A (beta-carotene). They contribute over 50% of total vitamin A. Similarly, thiamin, niacin an folic acid are essential for the normal functioning of visual and several other processes in the human body.
Chemical composition of fruit 

Chemical hazard in food industry

A food safety hazard can be defined as any factor present in food that has the potential to cause harm to the consumer.

Food safety hazards may be biological, chemical or physical object.

Chemical hazards can cause food borne disease and the consumer health. This includes naturally occurring substances, such as allergens, and toxins and contamination of food with chemicals substance, their residue or their degradation products at levels that can harm the consumers.

Some chemicals added to foods also make them unsafe. One potential chemical hazard is an excess quantity of sodium nitrite. This potential hazard was recognized decades ago when controls were established by the USDA to minimize this risk.

Other chemical hazards which should be considered include agricultural chemicals such as pesticide, herbicides, insecticides, fertilizers, antibiotics and other animal drugs, antibiotics, sulfa drugs, cleaning and sanitizing agents, oils and greases.

The above chemicals must be approved by federal agency before they can be legally used. If a chemical leaves a residue in food, the cognizant agency is responsible for establishing a tolerance level – the amount of residue that can legally remain in or on raw and processed foods.

Under some circumstances, chemical hazards can be eliminated or reduced through processing operations. For example, washing and peeling of agriculture produce is a very effective method for eliminating or reducing residues of agricultural chemicals.

Establishing safe food handling practices to avoid chemical hazards in the food supply, again like biological and physical hazard controls, will increase not only the safety of the food supply but also the margin of profit, reduce legal liabilities and promote good will to improve consumer confidence.
Chemical hazard in food industry

Chemical composition of coffee

The composition of coffee is very complex. The nonvolatile fraction of green coffee is composed primarily of water carbohydrates and fiber, proteins and free amino acids, lipids, minerals, organic acids, chlorogenic acids, trigonelline and caffeine.

The constituents of coffee that are important in making a good beverage are the flavor substances, the bitter substance and caffeine which responsibilities for the stimulating effect of the drink. Caffeine is a methylxanthine with bitter characteristics; however, it is responsible for no more than 10% of the perceived of the coffee bitterness.

The caffeine content of a cup of coffee (150 ml) is about 100 mg. Most people consume three cups of coffee a day and thus 300 mg of caffeine.

Protein is subjected to extensive changes when heated in the presence of carbohydrates. There is a shift of the amino acid composition of coffee protein acid hydrolysates before and after bean roasting.

Several organic acids are present in the aqueous extract from green coffee beans, the predominant being chlorogenic acid and the least acetic acid. Amino acids particularly alanine, glutamic acid and leucine are relatively increased.

The roasting process affects chemical composition because compounds break down or interact as they are heated for different lengths of time and at different temperatures. During roasting, formic and acetic acid are increased and chlorogenic and other acids like citric and malic partially destroyed.

Trigonelline is an alkaloid biologically derived from enzymatic methylation of nicotinic aid. It contributes to the bitterness of the brew and is a precursor for the formation of different classes of volatile compounds during roasting such as pyrroles and pyridines.
Chemical composition of coffee

Chemical composition of fruit

Fruit as a dessert item, is the mature ovaries of plants with their seeds. The edible portion of most fruit is the fleshy part of the pericarp or vessel surrounding the seeds.

The quality attributes and evaluation methods of fruits could be grouped into three categories: physical, chemical and physiological on the basis of analytical process and principle involved.

Fruits normally contain between 10% and 25% carbohydrates, less than 1% of protein and less than 0.5% of fat.

Compositions of fruit not only vary for a given kind in according to botanical variety, cultivation practices and weather but also to the changes with degree of maturity prior to harvest.

Carbohydrates, sugars, and starches are broken down into CO2, water and energy during catabolism.

Natural sugar such as fructose, glucose, and sucrose are the major contributors to the sweetness of fruits, whereas the tart flavor component is partially due to organic acids located in the cell sap.

Fruits like banana, plantain, date raisin, breadfruit, and jackfruit are the major sources of carbohydrates.

Proteins and amino acids are contained in dried apricot and fig. Meanwhile citrus fruit like oranges, grapefruit and lemons are high in citric acid.

Acidity varies with maturity of the plant usually decreasing as the fruit ripening.

Fruits are also known as an important sources of minerals and certain vitamins, such as vitamins A and C. It is well known that citrus are excellent sources of vitamin C.

Chemical composition of fruit