Chemicals in Food – Definition, Preservatives, Antioxidants, Examples-Chemistry in Everyday Life Class 12 Notes

Which Chemicals are found in Food ?

In various ways, chemistry has aided the modern world. The introduction of chemicals into our everyday food has made a significant influence. When chemicals are added to food, they serve three basic functions :

  • They contribute to the food’s long-term preservation. The shelf life of most processed foods ranges from a few months to several years. Only because we use chemicals as preservatives in these foods can we do this.
  • To improve the physical appearance of foods, chemicals are sometimes added. Certain chemicals will aid manufacturers in increasing the appeal of their products and making them more appealing to customers. They’re just for show.

Additives are chemicals found in foods. There are numerous additives that are considered safe for human consumption that we use today. However, not all of them are healthy. We use the following substances in our food: Food colours, Trans fats, etc.

Chemicals in Food Preservatives

In warmer climates, the sun aids in the drying of perishable foods such as fruits, vegetables, and fish. In frigid climates, nature aids in the preservation of perishable foods such as meat and fish for longer periods of time.

Natural fermentation and salting also aided man in the availability of a few key foods. The main agents for storing food are heat and cold. Many of these food preservation procedures are founded on scientific principles, resulting in the food preservation business becoming the world’s largest industry today. A preservative is a chemical that, when added to food, inhibits, delays, or stops the fermentation, acidification, or another breakdown of food caused by the proliferation of bacteria.

The following are the several types of food preservation methods,

  • Physical Methods
  • Chemical Methods

Physical Methods of Food Preservatives

  1. By removal heat: Refrigeration, freezing preservation, dehydro-freezing preservation, and carbonation are all involved. Foods such as fresh fruits, vegetables, meat, and fish can have their storage life extended by freezing them. Cooling lowers the temperature, which inhibits the growth of microorganisms.
  2. By the addition of heat: Pasteurization or sterilization can be done both statically and agitated. The first and most popular method of preservation is by adding heat. Canning or heat processing is another term for it. Because heating kills microorganisms, this approach is used to preserve solid and liquid goods on a wide scale.
  3. By removal of water: The procedures used to remove water include sun drying, low-temperature evaporation, freeze-drying, puff driving, and others. Sun drying is a common method for drying a wide range of foods, vegetables, grains, and other items around the world. To obtain high-quality dried products, numerous innovations have been implemented. The development of germs is inhibited as water is eliminated from the mixture.
  4. By irradiation: Food is preserved by ultraviolet (UV) or ionizing radiation. To suppress microbe development in the food sector, higher-intensity ultraviolet lights are utilized for irradiation. Baking items, for example. High-energy electromagnetic radiation is employed because it produces desired dietary effects and does not cause food to become radioactive.

Chemical Methods of Food Preservatives

  1. Addition of sugar: When it comes to preserving fruits for jams, jellies, and marmalades, adding sugar and then applying heat is a crucial step. This technique is simple, inexpensive, and simple to implement.
  2. Addition of salt: In food storage, salting is also used to keep fungus and bacteria at bay. It’s mostly used to make raw mango, lemon, and chilli pickles, as well as to keep fish items fresh. Osmosis is the process through which a cell loses water, dies, goes dormant, or stops working. It’s one of the oldest ways to keep food fresh.
  3. Addition of vinegar: Vinegar is used to preserve foods such as pickles, salad dressings, mustard, fish, and other similar items. Vinaigre, which means sour wine in French, is the source of the word vinegar.
  4. Addition of other chemicals: Preservatives include sodium benzoate, sorbic acid salts, and propionic acid, among others.

What are Artificial Sweetening Agents ?

Plants contain sweeteners such as cane sugar, glucose, maltose, and fructose. They’re sugar substitutes that aren’t artificial. They function as nourishment, providing calories to the body, in addition to being sweet. Certain compounds that do not occur naturally but are produced in the lab have a pleasant taste but no nutritional benefit. They are known as artificial sweeteners.

In 1879, Constantine Fahlberg and Era Ramsen discovered saccharin, an artificial sweetener. For diabetics, it was a crucial breakthrough. It does not need to be digested when it passes through the human digestive system. It has a nasty bitter flavour at high concentrations. C7H5SNO3 is Saccharin’s molecular formula. 

What are Artificial Sweetening Agents ?

Cane sugar is 550 times sweeter. It’s used to sweeten medications, toothpaste, low-calorie confectionery, soft drinks, and cold drinks, among other things.

Aspartame, which is 100 times sweeter than cane sugar, is another artificial sweetener. Because it is fragile at high temperatures, it is exclusively utilised in cold foods. Sucralose is a sucrose trichloro derivative that is 600 times sweeter than cane sugar. Sucralose is not used in cooking since it degrades at high temperatures. Alitame, another artificial sweetener, outperforms cane sugar by around 2000 times. As a result, it’s exceptionally sweet and temperature stable.

Aspartame, which is 100 times sweeter than cane sugar, is another artificial sweetener. Because it is fragile at high temperatures, it is exclusively utilised in cold foods. Sucralose is a sucrose trichloro derivative that is 600 times sweeter than cane sugar. Sucralose is not used in cooking since it degrades at high temperatures. Alitame, another artificial sweetener, outperforms cane sugar by around 2000 times. As a result, it’s exceptionally sweet and temperature stable.

What are Antioxidants ?

Antioxidants are substances that, when added to food, slow or stop food from oxidizing. Fats and oils are easily oxidized, becoming rancid and unpleasant to eat. Antioxidants are added to keep them from oxidizing and turning rancid. Free radicals are created during the oxidation of food. Antioxidants bind to free radicals and prevent food from oxidizing further.

For Examples,

  • Butylated hydroxytoluene (C15H24O) or BHT

Because of the electron cloud of the benzene ring, the free radical created by the interaction of a fat molecule with oxygen reacts with BHT to form the BHT radical, which is quite stable. The chain reaction is broken when the BHT radical does not combine with another fat molecule. It keeps fats from being oxidized and rancid. It’s used to keep the smell, colour, and flavour of food fresh.

  • Butylated hydroxyanisole (C11H16O2) or BHT

BHA, like BHT, is used to keep lipids from going rancid by preserving them. Butter, Cereals, chewing gum, snack foods, baked goods, beer, and dehydrated potatoes all contain BHA. Rubber, cosmetics, and petroleum products all contain this substance.

  • Sulphur dioxide

Their technological efficiency and versatility make them ideal for use as food additives. They serve as antimicrobials, structural modifiers, antioxidants, and enzyme inhibitors, among other things. Wines, fruit juices, pickles, and other beverages contain them. Sodium or potassium sulphite, as well as bisulphites, are the salts utilized.

Sample Questions (FAQS)

Question 1: What role do chemicals have in food?

Answer :

The introduction of chemicals into our daily food has made a significant influence. In fact, when chemicals are introduced to food, they perform three basic functions: They aid in the preservation of the food. The majority of processed foods on the market have a shelf life ranging from a few months to a few years.

Question 2: What is the most widely used chemical in food?

Answer:

In fact, food preservatives are one of the most common applications of chemicals in food. Sodium benzoate is the most common chemical. C7H5NaO2 is the chemical formula for sodium benzoate.

Question 3: Explain chemical methods for the preservation of food.

Answer:

Chemical Method for the preservation of food are:

  1. Addition of sugar : When it comes to preserving fruits for jams, jellies, and marmalades, adding sugar and then applying heat is a crucial step. This technique is simple, inexpensive, and simple to implement.
  2. Addition of salt : In food storage, salting is also used to keep fungus and bacteria at bay. It’s mostly used to make raw mango, lemon, and chilli pickles, as well as to keep fish items fresh. Osmosis is the process through which a cell loses water, dies, goes dormant, or stops working. It’s one of the oldest ways to keep food fresh.
  3. Addition of vinegar : Vinegar is used to preserve foods such as pickles, salad dressings, mustard, fish, and other similar items. Vinaigre, which means sour wine in French, is the source of the word vinegar.
  4. Addition of other chemicals : Preservatives include sodium benzoate, sorbic acid salts, and propionic acid, among others.

Question 4: Give one Example of Antioxidants.

Answer:

Example of Antioxidants is,

Sulphur dioxide: Their technological efficiency and versatility make them ideal for use as food additives. They serve as antimicrobials, structural modifiers, antioxidants, and enzyme inhibitors, among other things. Wines, fruit juices, pickles, and other beverages contain them. Sodium or potassium sulphite, as well as bisulphites, are the salts utilized.

Question 5: What is sodium chloride’s function in food?

Answer:

This chemical molecule is used in foods to prevent caking in a variety of items, including salt. This chemical has been deemed safe for use in foods by the WHO for decades.

Question 6: What compounds are used to extend the shelf life of food?

Answer:

Various chemicals are added to food to extend shelf life and make it more appealing. Colors, flavours, and sweeteners, antioxidants, fat emulsifiers, stabilizing agents, flour improvers, food preservatives, and nutritional supplements such as minerals, vitamins, and amino acids are the most common types of food additives.

Er. Neeraj K.Anand is a freelance mentor and writer who specializes in Engineering & Science subjects. Neeraj Anand received a B.Tech degree in Electronics and Communication Engineering from N.I.T Warangal & M.Tech Post Graduation from IETE, New Delhi. He has over 30 years of teaching experience and serves as the Head of Department of ANAND CLASSES. He concentrated all his energy and experiences in academics and subsequently grew up as one of the best mentors in the country for students aspiring for success in competitive examinations. In parallel, he started a Technical Publication "ANAND TECHNICAL PUBLISHERS" in 2002 and Educational Newspaper "NATIONAL EDUCATION NEWS" in 2014 at Jalandhar. Now he is a Director of leading publication "ANAND TECHNICAL PUBLISHERS", "ANAND CLASSES" and "NATIONAL EDUCATION NEWS". He has published more than hundred books in the field of Physics, Mathematics, Computers and Information Technology. Besides this he has written many books to help students prepare for IIT-JEE and AIPMT entrance exams. He is an executive member of the IEEE (Institute of Electrical & Electronics Engineers. USA) and honorary member of many Indian scientific societies such as Institution of Electronics & Telecommunication Engineers, Aeronautical Society of India, Bioinformatics Institute of India, Institution of Engineers. He has got award from American Biographical Institute Board of International Research in the year 2005.

CBSE Class 12 Chemistry Syllabus Download PDF

Below is the CBSE Class 12 Syllabus along with the marking scheme and time duration of the Chemistry exam.

S.NoTitleNo. of PeriodsMarks
1Solutions107
2Electrochemistry129
3Chemical Kinetics107
4d -and f -Block Elements127
5Coordination Compounds127
6Haloalkanes and Haloarenes106
7Alcohols, Phenols and Ethers106
8Aldehydes, Ketones and Carboxylic Acids108
9Amines106
10Biomolecules127
Total70

CBSE Class 12 Chemistry Practical Syllabus along with Marking Scheme

The following is a breakdown of the marks for practical, project work, class records, and viva. The total number of marks for all parts is 15. The marks for both terms are provided in the table below.

Evaluation Scheme for ExaminationMarks
Volumetric Analysis08
Salt Analysis08
Content-Based Experiment06
Project Work and Viva04
Class record and Viva04
Total30

CBSE Class 12 Chemistry Syllabus (Chapter-wise)

Unit -1: Solutions

  • Raoult's law.
  • Colligative properties - relative lowering of vapour pressure, elevation of boiling point, depression of freezing point, osmotic pressure, determination of molecular masses using colligative properties, abnormal molecular mass.
  • Solutions, Types of solutions, expression of concentration of solutions of solids in liquids, solubility of gases in liquids, solid solutions.
  • Van't Hoff factor.

Unit -2: Electrochemistry

  • Redox reactions, EMF of a cell, standard electrode potential
  • Nernst equation and its application to chemical cells
  • Relation between Gibbs energy change and EMF of a cell
  • Kohlrausch's Law
  • Electrolysis and law of electrolysis (elementary idea)
  • Dry cell-electrolytic cells and Galvanic cells
  • Conductance in electrolytic solutions, specific and molar conductivity, variations of conductivity with concentration.
  • Lead accumulator
  • Fuel cells

Unit -3: Chemical Kinetics

  • Rate of a reaction (Average and instantaneous)
  • Rate law and specific rate constant
  • Integrated rate equations and half-life (only for zerfirst-order order reactions)
  • Concept of collision theory (elementary idea, no mathematical treatment)
  • Factors affecting rate of reaction: concentration, temperature, catalyst;
  • Order and molecularity of a reaction
  • Activation energy
  • Arrhenius equation

Unit -4: d and f Block Elements  

  • Lanthanoids- Electronic configuration, oxidation states, chemical reactivity and lanthanoid contraction and its consequences.
  • Actinoids- Electronic configuration, oxidation states and comparison with lanthanoids.
  • General introduction, electronic configuration, occurrence and characteristics of transition metals, general trends in properties of the first-row transition metals – metallic character, ionization enthalpy, oxidation states, ionic radii, color, catalytic property, magnetic properties, interstitial compounds, alloy formation, preparation and properties of K2Cr2O7 and KMnO4.

Unit -5: Coordination Compounds  

  • Coordination compounds - Introduction, ligands, coordination number, color, magnetic properties and shapes
  • The importance of coordination compounds (in qualitative analysis, extraction of metals and biological system).
  • IUPAC nomenclature of mononuclear coordination compounds.
  • Bonding
  • Werner's theory, VBT, and CFT; structure and stereoisomerism

Unit -6: Haloalkanes and Haloarenes  

  • Haloarenes: Nature of C–X bond, substitution reactions (Directive influence of halogen in monosubstituted compounds only). Uses and environmental effects of - dichloromethane, trichloro methane, tetrachloromethane, iodoform, freons, DDT.
  • Haloalkanes: Nomenclature, nature of C–X bond, physical and chemical properties, optical rotation mechanism of substitution reactions.

Unit -7: Alcohols, Phenols and Ethers   

  • Phenols: Nomenclature, methods of preparation, physical and chemical properties, acidic nature of phenol, electrophilic substitution reactions, uses of phenols.
  • Ethers: Nomenclature, methods of preparation, physical and chemical properties, uses.
  • Alcohols: Nomenclature, methods of preparation, physical and chemical properties (of primary alcohols only), identification of primary, secondary and tertiary alcohols, mechanism of dehydration, and uses with special reference to methanol and ethanol.

Unit -8: Aldehydes, Ketones and Carboxylic Acids   

  • Carboxylic Acids: Nomenclature, acidic nature, methods of preparation, physical and chemical properties; uses.
  • Aldehydes and Ketones: Nomenclature, nature of carbonyl group, methods of preparation, physical and chemical properties, mechanism of nucleophilic addition, the reactivity of alpha hydrogen in aldehydes, uses.

Unit -9: Amines    

  • Diazonium salts: Preparation, chemical reactions and importance in synthetic organic chemistry.
  • Amines: Nomenclature, classification, structure, methods of preparation, physical and chemical properties, uses, and identification of primary, secondary and tertiary amines.

Unit -10: Biomolecules     

  • Proteins -Elementary idea of - amino acids, peptide bond, polypeptides, proteins, structure of proteins - primary, secondary, tertiary structure and quaternary structures (qualitative idea only), denaturation of proteins; enzymes. Hormones - Elementary idea excluding structure.
  • Vitamins - Classification and functions.
  • Carbohydrates - Classification (aldoses and ketoses), monosaccharides (glucose and fructose), D-L configuration oligosaccharides (sucrose, lactose, maltose), polysaccharides (starch, cellulose, glycogen); Importance of carbohydrates.
  • Nucleic Acids: DNA and RNA.

The syllabus is divided into three parts: Part A, Part B, and Part C. Part A consist of Basic Concepts of Chemistry, which covers topics such as atomic structure, chemical bonding, states of matter, and thermochemistry. Part B consists of Topics in Physical Chemistry, which includes topics such as chemical kinetics, equilibrium, and electrochemistry. Part C consists of Topics in Organic Chemistry, which covers topics such as alkanes, alkenes, alkynes, and aromatic compounds.

Basic Concepts of Chemistry:

  • Atomic structure: This section covers the fundamental concepts of atomic structure, including the electronic configuration of atoms, the Bohr model of the atom, and the wave nature of matter.
  • Chemical bonding: This section covers the different types of chemical bonds, including ionic, covalent, and metallic bonds, as well as the concept of hybridization.
  • States of the matter: This section covers the three states of matter - solid, liquid, and gas - and the factors that influence their properties.
  • Thermochemistry: This section covers the principles of thermochemistry, including the laws of thermodynamics and the concept of enthalpy.

Chapters in Physical Chemistry:

  • Chemical kinetics: This section covers the study of the rate of chemical reactions and the factors that influence it, including the concentration of reactants, temperature, and the presence of catalysts.
  • Equilibrium: This section covers the principles of chemical equilibrium, including the concept of Le Chatelier's principle and the equilibrium constant.
  • Electrochemistry: This section covers the principles of electrochemistry, including the concept of half-cell reactions, galvanic cells, and electrolysis.

Chapters in Organic Chemistry:

  • Alkanes: This section covers the properties and reactions of alkanes, including their structure, isomerism, and combustion.
  • Alkenes: This section covers the properties and reactions of alkenes, including their structure, isomerism, and addition reactions.
  • Alkynes: This section covers the properties and reactions of alkynes, including their structure, isomerism, and addition reactions.
  • Aromatic compounds: This section covers the properties and reactions of aromatic compounds, including their structure, isomerism, and electrophilic substitution reactions.

In addition to the topics covered in the syllabus, the CBSE Class 12 Chemistry exam also tests students on their analytical and problem-solving skills, as well as their ability to apply the concepts learned in the classroom to real-world situations.

Students can also check out the Tips for the Class 12 Chemistry Exam. They can easily access the Class 12 study material in one place by visiting the CBSE Class 12 page at ANAND CLASSES (A School Of Competitions). Moreover, to get interactive lessons and study videos, download the ANAND CLASSES (A School Of Competitions) App.

Frequently Asked Questions on CBSE Class 12 Chemistry Syllabus

Q1

How many chapters are there in the CBSE Class 12 Chemistry as per the syllabus?

There are 10 chapters in the CBSE Class 12 Chemistry as per Syllabus. Students can learn all these chapters efficiently using the study materials provided at ANAND CLASSES (A School Of Competitions).

Q2

What is the marking scheme for CBSE Class 12 Chemistry practical exam according to the syllabus?

The marking scheme for CBSE Class 12 Chemistry practical exam, according to the syllabus, is 8 marks for volumetric analysis, 8 marks for salt analysis, 6 marks for the content-based experiment, 4 marks for the project and viva and 4 marks for class record and viva.

Q3

Which is the scoring chapter in Chemistry as per CBSE Class 12 syllabus?

The chapter Electrochemistry in Chemistry is the scoring chapter as per CBSE Class 12 syllabus.