Chemistry in Everyday Life
The surrounding world is supposed to be the unique and complex structure, the efficient performance of which significantly depends on the various physical and chemical processes of interaction of the different substances and their properties. In fact, chemistry occupies the important place in the everyday life. The value of chemistry in human life cannot be overestimated. The fundamental areas in which chemistry has its constructive impact on people's lives are related to the emergence and development of human life as well as its quality. The various chemical processes within the human body and brain influence health, behavior as well as emotions and mental state. In addition, the various chemical processes are used for the manufacture of the material products aimed to satisfy the human needs. For example, chemistry in its different variations can be used to increase the fertility of the soil, facilitating the human work. It saves time, clothes, helps to preserve health, creates warmth and comfort and even changes the appearance of people. Based on the mentioned above, the following paper is aimed to analyze the importance of chemistry in everyday life. In fact, the paper will discuss the significance of chemistry in nutrition and food industry as well as the chemistry of smell and taste of food products.
Chemistry in Food and Nutrition
In everyday life, every person carries the chemical reactions even without knowing it. When lowering the slices of lemon into a glass of hot tea, there can be seen the weakening of tea color. In fact, the tea here acts as an acid indicator, like litmus. The similar acid-base interaction is manifested on the wetted with vinegar chopped blue cabbage. The cabbage with vinegar turns pink. While lighting a match, mixing sand and cement with water or extinguishing water lime, people provide real and sometimes quite complex chemical reactions. In fact, cooking is also the chemical processes. No wonder that women chemists are often very good cooks. Indeed, cooking in the kitchen sometimes resembles performing organic synthesis in the laboratory. Only instead of flasks and retorts, in the kitchen people use pots and pans. It means that the list of the chemical processes that people hold in their daily lives is endless. Any living organism is carried out the various chemical reactions. The processes of digestion, breathing of animals and men are based on chemical reactions.
Napoleon’s Buttons provides the overview of the various chemical reactions which make spices so valuable and delicious to people. In addition, the book describes the history of spices in the different periods of human development. Napoleon’s Buttons states that spices have been known from the very beginning of history. It was one of the most valuable items of trade in the ancient world and the Middle Ages, when the salt was valued more than gold. Spice trade began to develop everywhere, starting with the Middle East around 2000 BC. The first sales included cinnamon and pepper. In 3500 BC, Ancient Egyptians used spices not only for food, but also as cosmetics or medicines. The tracts with the description and study of the properties of spices are found among the earliest manuscripts. The instructions on the preparation on the basis of spice plants drugs are found on Egyptian papyri, but most of the people knew the spices of India and the Far East, which used them to give different flavors and a variety of simple dishes. The black pepper, cinnamon, ginger, turmeric and cardamom are the first spices, widely used in India. Eating a variety of spices was the basis of the first Ayurvedic medicine. People knew about the herbs and spices in ancient China. The mention of the beneficial properties of spices are found in the writings of Confucius and other ancient treatises mentioned that Chinese courtiers chewed dried clove buds front of an audience with the emperor, thus refreshing the breath. In ancient Rome, the country of winegrowers, people added spices to the wine as well as the flavored water. The arab doctors prepared on the basis of herbs and sugar first Persian medicinal syrups, which included ginger, black pepper, nutmeg, cloves, cinnamon and cardamom.
However, there comes a difficult times and the Roman Empire collapsed. The Turks captured Baghdad, and the Catholic Church forbade merchants to trade with Western infidel Muslims. The Catholic states even went on a crusade, and returning from the Middle East, the Crusaders brought with them not only the jewels and fabrics, but also spices. They brought not only pepper and cinnamon, but also some new ones, such as nutmeg and mace, which were first used in Europe as incense to the emperor Henry IV's coronation. Later people began to make fragrance oils from spice mixtures. The composition of the ointment initially composed of over 50 spices, while its flavor remained for years.
The food products contain the various chemical compounds such as aldehydes. ketones, acids, alcohols, pigments etc., which cause important properties such as taste, smell, color and determine palatability advantages and product quality as based on the change of taste and smell of the product, there can be defined the presence of foreign substances or incipient damage. The color, taste and smell of food is affected by melanin, the products of caramelization and melanoidins as well as fat-soluble pigments. For example, C18H27O3N or chili peppers has the variety of colors, sizes, and shapes due to the different chemical compounds responsible for the pungent flavor and taste. Piperine, capsaicin and Zingerone increase the secretion of saliva, stimulation the digestion process. Thus, being inspired by Napoleon’s Buttons materials, it has been decided to continue the analysis of the chemistry of smell and taste within the food products.
The Chemistry of Smell and Taste in Food
The amino acid of tyrosine causes the dark color of foods (such as rye bread), participating in the synthesizes of dark-colored pigment called melanin. Under the action of a copper-containing enzyme, tyrosine is converted into dihydroxyphenylalanine (DOPA), which is further oxidized to form indolhinon, the polymerization of which leads to the synthesis of melanin.
By the way, tyrosine and is responsible for the coloring of hair, skin, eyes. Melanin formation is enhanced under the influence of ultraviolet rays (for example, sunburn) and can cause malignant neoplasms. The hereditary disease of albinism is characterized by the absence of the enzyme tyrosinase, so that there can be seen skin and hair pigmentation.
The darkening of food may occur through oxidative or non-oxidative reactions. The oxidative or enzymatic browning is caused by the reaction between the substrate and the phenolic oxygen, catalyzed by the polyphenol oxidase enzyme. This darkening is observed in slices of apples, bananas, etc. The nonoxidative or non-enzymatic browning is also observed quite often in food. Non-enzymatic browning reactions are caused by melanoidin colored pigments and many have different volatile components. This is connected with the phenomenon of caramelization. Such reactions are responsible for the odor of a food product in the production process of which implies the process of thermal treatment. The products of thermal decomposition of sugars include pyran and furan compounds as well as furanones, lactones and esters. The presence of certain aromatic compounds gives each product its inherent flavor.
The heating of mono- and disaccharides at a temperature of 1000C or above promotes the complex reaction of caramelization. The reaction is catalyzed by low concentration of acids, alkalis and some salts. This produces brown products with a typical caramel flavor. By adjusting the conditions by changing the composition and concentration of sugars, the extent and duration of exposure to heat, pH as well as the presence of impurities, it is possible to direct the reaction mainly to flavor or in the direction of formation of colored products.
The caramelization of sucrose, glucose and fructose is of particular importance in food industry. In fact, fructose is particularly sensitive to heat, so its caramelization occurs 6-7 times faster than glucose. Typically, sucrose is used for caramel color and flavor. The heating of sucrose in the presence of sulfuric acid or ammonium salts creates the intensely colored polymers used in various food products as well as in the manufacture of beverages, candies, etc. The complex reactions with caramelization lead to the formation of various systems with unique taste and flavor. For example, maltol and isomaltol have the smell of baked bread, 2-N-4-hydroxy-5-metilfuranon has the aroma of roasted meat. Moreover, these products have sweet taste, which also determines their significant role in food industry.
It should be noted the dual function maltol and isomaltol. They have strong caramel flavor and sweetness. Furthermore, maltol affects the texture of the food product, giving the effect of velvety. Compared to maltol, iIsomaltol has 6 times more index of sweetness. In the absence of buffer salts, there may form a polymer compound of humin with bitter taste (average formula S125N188O80). In the production of food products, it is necessary to prevent its formation.
The moderate (basic) heating of carbohydrates leads to anomeric changes, breaking glycoside bonds as well as the formation of new glycoside bonds. However, the dehydration implies the cleavage from glucose molecule one or two water molecules, while the formed products are connected with each other or with a sucrose molecule. The cleavage of three water molecules forms hydroxymethylfurfural, while the further transformation is accompanied by the destruction of the carbon skeleton and the formation of a variety of products (formic acid, levulinic acid etc.). The cleavage of two molecules of water from sucrose caused the formation of karamelan S12N18O9, i.e. the water-soluble compound of yellow color. The cleavage of three molecules creates caramel S36N50S25 and karamelin. The degree of polymerization of the formed products may be different. If the carbohydrate concentration is low (10-30%), the formation of hydroxymethylfurfural occurs easier, while at higher concentrations (70-80%), there can be seen the active condensation processes.
At the temperature from 40-600С to 1000C, there can be noticed the speed up in the process of interaction of proteins or amino acids with reducing sugars, accompanied by the formation of carbonyl compounds and melanoidins (Maillard reaction). The Maillard reaction is the first reaction step of the non-enzymatic browning of foods. The essence of the reactions lies in the interaction of the melanoidins amino acids with the amino glycoside hydroxyls sugars. The melanoidins reduce the bioavailability of products. There can be noticed the decrease of digestibility of amino acids due to the lack enzymes of the digestive tract. The characteristic features of the Maillard reaction implies the darkening of the product due to the formation or difficulties insoluble dark compounds as well as decrease of sugars and amino nitrogen groups.
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In addition to the Maillard reaction, there occurs the formation of hydroxymethylfurfural dehydration, the formation of dicarbonyl compounds and melanoidin pigments which are formed at the final stages and have a color from red-brown to dark brown. The colloidal poorly soluble melanoidins with the typical aroma are the result of aldol condensation and polymerization.
The most intensively flows melanoidins in neutral and alkaline media, it is easier to pass the concentrated compounds of NaHSO3, H2SO4 and H2O2. The melanoidins compounds are actively involved into the formation of flavor and to some extent taste of the finished product. The speed of darkening of disaccharides (such as sucrose) and polysaccharides can limit the rate of hydrolysis and decomposition of sugars.
The brown pigments melanoidin is explained by the absorption spectrum in the visible band reception, composed of overlapping absorption spectra of many chromophores. The pigments imply the mixture of compounds with a similar structure, but with different molecular weights. The pigments formed in modeling environments are unsaturated polycarboxylic acids with an extended conjugated bond system comprising a carboxyl group. Furthermore, it is possible to note the presence of hydroxyl, enol and amine functions.
Because the Maillard reaction involves the proteins and amino acids, it is obvious that there is a certain loss of them as nutrient supply. The large capacity for the Maillard reaction is not unique to lysine, but also for other important amino acids such as L-arginine and L-histidine. It means that if the darkening reaction takes place in the production, storage and preservation of food, there can be noticed some loss of amino acids and nutritional value. In some cases, even relatively mild processing conditions can produce relatively large losses.
However, the loss of amino acids can occur not only in the formation of melanoidin pigments. At the same time, in some cases the formation of foreign odor in food products is unacceptable or undesirable. Therefore, it is necessary to know the factors that influence the reaction of melanoidins to manage the process in the right direction. These factors include temperature, pH, humidity, the presence of certain metal ions and sugar structure.
The melanoidins reaction plays an important role in the processes that occur in the processing of food raw materials and significantly affecst the quality of finished products. Thus, due to the darkening of the melanoidins sugar syrup, reducing alcohol yield in the processing of low-quality corn, the formation of color and flavor with "anguish" red malt and mash in brewing. The establishment of tasty, crispy, golden-brown crust of bread, its taste and aroma are also largely associated with melanoidins, occurring mainly during baking. The products formed in the preparation of wines, manufacture of cognac and champagne occur in the process of melanoidins, affecting their color, taste and aroma. The reactions of melanoidins are associated with darkening of fruit juice during storage, appearance, taste and smell of finished meat products. The melanoidins can bind up to 25% of protein, vitamins, amino acids, while decreasing the activity of enzymes and many biologically active compounds, reducing the nutritional value of the products.
The perception of flavor and taste are a very complex chemical processes, associated with the interaction of the molecules responsible for the flavor substance to the corresponding receptor. In humans, the sensory system has several types of taste receptors, i.e. salty, sour, bitter and sweet. They are located in separate parts of the tongue and react to various substances. The individual taste can influence each other, especially under the simultaneous effect of several compounds. The overall effect is dependent on the nature of the compounds that cause the taste sensation and the concentrations of substances used. It is equally difficult problem reactions to the flavor (smell) of food. The smell - it is a special property of the substance, which is perceived by the senses (olfactory receptors) located in the upper part of the nasal cavity. This process is called the sense of smell. The aroma of the food industry is one of the most important factors determining the popularity of a product on the market today. The paper discussed the oxidative or non-oxidative reactions chemical reactions which cause the darkening of food and serve as the reasons to the changes in smell and taste of the products. It has been proved that the color, taste and smell of food is affected by melanin, the products of caramelization and melanoidins as well as fat-soluble pigments.