Cannizzaro reaction

Certain aldehydes, upon treatment with sodium or potassium hydroxide, are converted to equal amount of the corresponding carboxylate anion and alcohol. This is known as the Cannizzaro reaction.

The reaction is actually an oxidation-reduction reaction in which one molecule of an aldehyde is oxidized while a second one is reduced.

This reaction works only with aldehydes (such as benzaldehyde) that lack α hydrogen atoms. The reaction requires a strong base, and the rate law is found to depend on the concentration of the base and the square of concentration of the aldehyde.

When the aldehydes are not identical, the reaction is called a ‘crossed Cannizzaro reaction’. Cannizzaro reaction is used for the preparation of various alcohols and acid.
Cannizzaro reaction

Coffee constituents of chlorogenic acid

The chlorogenic acids are ubiquitous in the plant kingdom. Although chlorogenic acids are common in vegetables foodstuffs, the relatively large quantity present in coffee make it an important dietary sources.

Chlorogenic acid and its isomers represent major coffee constituents of phenolic acid. They are family esters of quinic acid with several hydroxycinnamic acids, particularly caffeic, ferulic, p-coumaric acids.

In coffee they are essentially mono- and diesters and by far the prevailing acids. Other esters may occur but generally only in small amounts.

The quality of coffee depends in part on the relative proportion of mono and dichlorogenic acids, The ratio between these two acids is slightly less in robusta than in arabica. An excess of dichlorogenic acids might result in a metallic after-taste in the beverage.

Oral ingestion by man of 200 mg of chlorogenic acid was found to stimulate stomach secretion with enhancement of hydrochloric acid production. Caffeic acid had the same effect, and quinic acid, XII was inactive.
Coffee constituents of chlorogenic acid

Table sugar of sucrose

Cane and beet sugar are identified in technical terms as sucrose. It is composite molecule made of one molecule each of glucose and fructose.

Sucrose is one of the most abundant carbohydrates found in nature and is a major component of the food chain. Sucrose is a 12-carbon sugar that is broken down in the intestine to glucose and fructose, hence utilized as a source of energy.

The official name of sucrose, according to the IUPAC-IUB Commission of Biochemical nomenclatures is β–D-fructofuranosyl-α-D-glucopyranoside.

Solubility of sugars varies with sugar types. For example, sucrose is more soluble than glucose and less soluble than fructose. This influence candy types and product success. It is the second most soluble sugar – two parts can dissolve in one part of room temperature.

To increase the solubility of sucrose and reduce possible undesirable crystallization, sucrose may be treated by inversions become invert sugar. When a sucrose solution is heated with an acid, some of the sucrose breaks down into equal parts of two simple sugars, dextrose and levulose. A mixture of equal parts of dextrose and levulose is called invert sugar.
Table sugar of sucrose

What is aroma chemicals?

Aroma chemicals are uniform compounds, which can be both of natural or synthetic origin.

The aroma component of flavor is due to a complex mixture of volatile 0rganic chemicals. It comprise organic compounds with a defined chemical structure.

Aroma chemicals may be added directly to foods and beverages or used as raw materials in flavor compositions.

Strawberries

A simple flavor may have 100-300 volatile constituents such strawberry or grape. The thermal generation of volatiles during cooking and processing is one of the key mechanisms for the formation of aroma in food. Foods that are more complex in flavor, for example those resulting from Maillard reaction may contain 900 or more volatile constituents.

Other than Maillard reactions, there are other chemical reactions, including Strecker degradation, caramelization, the degradation of thiamin and ferulic acid and lipid oxidation.

They are partially lipid-soluble organic chemicals of low molecular weight. Many of these have been identified since the invention of gas chromatography.

There are nearly 7000 compounds of aroma chemicals in foods. Many of these aroma compounds are present naturally in foods while other are the result of fermentation, thermal processing or deteriorative reactions e.g. lipid oxidation.

What is aroma chemicals? 

Chemical Composition of Cereals

Chemical Composition of Cereals
The chemical composition of the cereals varies widely and depends on the environmental conditions, soil, variety and fertilizer.

Wheat has a higher protein content than other cereals: The protein content varies from 7 to 22% depending on the variety. However, because of low availability of some essential amino acids in wheat, its biological value requires addition or supplementation with other amino acids.

Several research efforts have focused in producing different wheat varieties with higher protein and essential fatty acids content.

Carbohydrates are the major chemical composition of the corn. However, the maize corn kernel is more than a rich source of carbohydrate, it is a source of enzymes for the study of biosynthesis and genetic markers for genetic, biochemical, and genetic engineering studies.

The starch granule is formed inside an amyloplast and arranged in an insoluble granule. Starch is the major carbohydrate in the kernel and comprises close to 72% of its dry weight.

Starch also is found in the embryo, bran, and tip cap. Amylose makes up 25-30% of the starch whereas amylopectin composes 70-75% of the starch.

Monosaccharides , such as fructose and glucose are found in equal proportions in the endosperm. Among the disaccharides sucrose is the major sugar in kernels that comprise only 4-8% of kernel dry weight: maltose is also found at less than 0.4% of the kernel dry weight.

The corn bran consists of 70% hemicellulose, 23% cellulose and 0.1% lignin on a dry weight basis.
The protein content of the corn shows that it is poor in essential amino acids such as tryptophan, lysine and threonine, valine and sulfur amino acids.

The corn has only 4.4% oil (dry basis), but the amount of corn oil production is enormous, even though it is not considered as an oil seeds crop.

Triglycerides are the major composition (98.8%) of the refined commercial corn oil.

Corn oil is very stable compared with other seed oils owing to its flow level of linolenic acid and the presence of natural antioxidant.

The composition of rice and its fraction depends on the cultivars, environmental conditions and processing. The rice components distributes differently in aleurone, embryo and other parts of the grain.

The average brown rice protein content ranges from 4.3 to 18.3% with a mean value of 9.2%.

Protein is the second most important rice component after carbohydrates.

The ouster tissue of the rice grain are rich in water soluble proteins (albumin) and also salt soluble proteins (globulin), but the endosperm is rich in glutelin.

The milling fraction of the rice grain has a limited prolamin (alcohol free proteins), and the non-protein nitrogen (NPN) of the rice is about 2 -4%.

Rice starch is composed of linear fraction - amylose and branched fraction -amylopectin – that is a major factor in the eating and cooking quality of the rice.
Chemical Composition of Cereals

Flavoring Agents

Flavoring Agents
Flavoring agents are the largest single group of food additives. Food and beverage applications of flavors include dairy, fruit, nut, seafood, spice blends, vegetables and wine flavoring agents. They may complement, magnify, or modify the taste and aroma of the foods.

There are over 1200 different flavoring agents used in foods to create flavor or replenish flavors lost or diminished in processing, and hundreds of chemicals may be used to simulate nature flavors. Alcohols, esters, aldehydes, ketones, protein hydrolysates and MSG are examples of flavoring agents.

Natural flavoring substances are extracted from plants, herbs and spices, animals, or microbial fermentations. They also include essential oils and oleoresins (created by solvent extract with solvent removed), herbs, spices and sweetness.

Synthetic flavoring agents are chemically similar to natural flavorings, and offer increased consistency in use and availability. They may be less expensive and more readily available than the natural counterpart although they may not adequately simulate the natural flavor.

Some examples of synthetic flavoring agents include amyl acetate, used as banana flavoring benzaldehyde, used to create cherry or almond flavor, ethyl butyrate for pineapple, methyl anthranilate for grape, methyl salicylate for wintergreen flavor, and fumaric acid, which is an ideal source of tartness and acidity in dry foods.

Flavor enhancers such as monosodium glutamate (MSG) intensify or “bring out,” enhance or supplement the flavor of other compounds in food; they have a taste outside of the basic sweet, sour, salty or bitter. Monosodium glutamate was chemically derived from seaweed in the early 1900s, but is manufactured commercially by the fermentation of starch, molasses, or sugar.
Flavoring Agents