Food Microbiology

Methods of food preservation – Physical and Chemical Methods 

Food preservation methods have resulted in increasing the duration or shelf time of food items through using a variety of preservation methods.

MN Editors avatar
MN Editors
This article writter by MN Editors on July 28, 2022

Microbiology Notes is an educational niche blog related to microbiology (bacteriology, virology, parasitology, mycology, immunology, molecular biology, biochemistry, etc.) and different branches of biology.

Follow
X

Follow

E-mail :*
* Your personal data will be used to support your experience throughout this website and for other purposes described in our Privacy Policy. I hereby agree and consent to the privacy policy.
· 18 min read >
Methods of food preservation - Physical and Chemical Methods 
Methods of food preservation - Physical and Chemical Methods 
  • Food preservation methods have resulted in increasing the duration or shelf time of food items through using a variety of preservation methods.
  • Food preservation methods are a combination of conventional and innovative techniques.
  • It is possible to preserve the freshness of the food and extend the shelf-life by using various methods of food preservation like drying, freezingand canning and salting, among others.

Principles of food preservation

The principle of food preservation is prevention against decomposition by microbial organisms, the preventative measures against self-decomposing food items, and protection from the many mechanical, chemical and physical harms to food items.

  • Reduces or stops the microbial decomposition: It results in the inhibition of growth of microbial cells (microbiostatic) or killing bacteria and microbes (microbicidal). Food preservation ensures that there is no asepsis that is “keeping the microbes out” by removing or removing microbes. It impedes the growth of microbial organisms through various methods , including smoking, chilling, freezing etc. and kills microorganisms using methods such as pasteurization, radiation and so on.
  • Protects food items from self-decomposition: The process involves either the activation of enzymes in food by means such as salting, picking sugaring, etc. or removal of pro-oxidants making use of antioxidants.
  • Reduces the risk of mechanical, chemical and physical damage caused by flavor encapsulation, rancidity, bruises, etc.

Need for Food Preservation

If food is in greater quantity than the current use or consumption, it must be stored for future use. Therefore, preservation efforts ensure that food is properly utilized. The preservation of fresh produce is necessary for the these reasons:

  • In order to increase the availability of certain food items with a shorter growing season , such as vegetables and fruits, for use all year round.
  • To make use of surplus crops and to avoid the waste of crops.
  • To save money by preserving food items at times when they are plentiful cheap and good quality.
  • To produce food that can be stored to distribute, transport and store and can be made available throughout the day.
  • For the purpose of meeting the demands of people in need of food in difficult and remote zones.
  • In order to ensure that there is a supply of protective food items in hotels, homes and other similar locations.

Goals and objectives of Food Preservation

  • The purpose of food preservation is to avoid undesirable changes to the wholesomeness, nutritional value or taste of food items and to reduce the physiological, physical, and chemical modifications that are objectionable and remove contamination.
  • The aim of preservation of food is to prolong the shelf life of food items while ensuring its safety. It is the only way to ensure its availability in times of depletion or natural drought.
  • The primary goals of food preservation is to extend the an in-between phase in bacteria growth; preventing unwanted autolysis, minimising physical or pest harm and preventing the action of microbial.

The importance of food Preservation

Food preservation practices are as old as the human race. It played an important part in the development of civilization. In the case of a delay in the processing or consumption of fresh foods can alter its freshness, colour texture, palatability, nutritive value, organoleptic desireability as well as aesthetics and security. To keep food on hand throughout the year, human beings have devised methods to extend the shelf life of their food items i.e. to keep them in good condition. The process of rotting could be delayed by adding preservatives or optimizing the storage conditions or applying the latest methods. Thus, preserving food is essential to extend their shelf-life.

Food preservation definition

Food preservation is the method by which you can keep food items for a longer time using a variety of food preservation techniques such as drying, salting, freezing, sugaring, and so on. The field of preservation for food includes a field of science that targets the quality and edibility of food by preventing decay of food. In addition, it concentrates on the shelf-life of food products to ensure that food can be stored in a good state for use in the future and also protects food from contamination by stopping or eliminating microbes that grow.

Food preservation techniques is classified into two categories that is, namely

  1. Physical Methods of Food Preservation
  2. Chemical Methods of Food Preservation

Physical Methods of Food Preservation

  1. Preservation by low temperatures
  2. Preservation by high temperature
  3. Preservation by drying
  4. Preservation by irradiation

1. Preservation by low temperatures

  • The metabolism of living tissue is determined by the temperature in the environment.
  • Low temperatures are used to slow down chemical and enzymatic reactions that occur in food products.
  • Furthermore, lowering the temperature slows or stops the development as well as activity of microorganisms within the food.
  • The lower temperatures, the lower is the rate over natural activity. Cooling slows or prevents the degradation of food.
  • The use of refrigeration and freezing is among the most ancient ways for preservation. Mechanical ammonia refrigeration systems developed in 1875 enabled the development of commercial refrigerated warehouses and freezing.

Methods of Food Preservation by low Temperature

  1. Cellar storage temperature (15°C): Cellar storage temperature (15degC) is typically used for storage of food surpluses such as potato, root crops, apples, onions etc. for a limited time.
  2. Refrigeration/ chilling temperature (0 to 5°C): Foods stored at this temperature reduce the activity of microbial organisms and chemical changes that cause the spoilage. Refrigeration or cold storage that is mechanical is used to accomplish this. Examples include: eggs, meats, poultry fish fresh milk, dairy products fruit, vegetables, and so on. which can be kept for 2-7 days in refrigeration.
  3. freezing food preservation (-18 to -40°C):  When food is frozen, the water contained in food is transformed into the form of ice, which makes the food inaccessible for reactions to take place as well as for microorganisms and microbes to flourish. Most perishable foods like poultry, meats, fish, ice-creams, peas, vegetables, juice concentrates, etc. can be stored for several months in this climate. In vegetable products, enzymes could still cause negative effects on flavor and texture when frozen. Blanching and heating will, in turn, remove the enzymes before vegetables are frozen.

2. Preservation by High Temperature

  • Heating was practiced for centuries before the mechanism was fully recognized. Food items are heated up or cooked.
  • It is used to deactivate the organisms or enzymes that have a importance to spoilage in food items.
  • Microorganisms are killed with heat, because the heat’s application coagulates the proteins in food and activates the enzymes that kill microorganisms, which leads to the destruction of microorganisms.
  • Examples include all kinds of food cooked such as pasteurization, sterilization of milk with UHT (ultra high temperatures) as well as canning.
  • The most crucial current applications of preservation of heat is pasteurization of milk.

Methods of Food Preservation by High Temperature

(a) Pasteurization (temperature below 100°C)

  • Pasteurization is a method of heat treatment using temperatures of less than 100degC which kills a small portion but not all microorganisms found in food.
  • Milk, for instance, is typically heated to 63 degrees Celsius for 30 minutes or 71degC for 15 secs or UHT 138degC over 4 to 5 seconds.
  • Examples include wine, milk beer, fruit juices and aerated water which are often pasteurized.
  • The heating method can be hot water, steam dry heat, as well as electric energy.
  • The products are quickly cooled following heating.
  • Pasteurization is typically accompanied with other methods to extend the shelf-life of food products.

There are three methods of pasteurization.

  1. Bottle or Holding Pasteurization: This technique is widely used to preserve fruit juices. The juice that is extracted is separated and then placed in bottles. The bottles are then sealed to keep them air tight and then pasteurized.
  2. Over Flow Method: The juice is heated to approximately 2.5oC greater than the temperature of pasteurization and filled into hot sterilized bottles. The bottles that are sealed are sterilized at temperatures 2.5oC lower than the filling sealing temperature, and then chilled.
  3. Flash Pasteurization:  The juice is rapidly heated to around 5.5oC more than the pasteurization temperature and maintained at this temperature for approximately an hour. This process was developed specifically for canning organic orange juice, grape or apple juice. It is a great way of reducing flavor loss and keeping the vitamins.

(b) Boiling (temperature at 100°C)

  • The preparation of rice, veggies and meats, fish, etc. at home is typically accomplished through boiling food in water. It is done at an oven that is heated to about 100degC.

(c) Canning (temperature above 100°C)

  • Canning is the method by which food items are cooked in sealed (airtight) cans or jars to a temperature which destroys microorganisms as well as inactivates enzymes that can pose dangerous to health or cause food to get spoiled.
  • The vacuum seal created by cooling and heating during the process makes sure that no microorganisms can be introduced inside the item.
  • The amount of heat produced and the duration of the heating process will depend on the kind of food item and the types of microorganisms that will likely to be found within it.
  • Fruits that are high in acid like tomatoes like tomatoes and fruits can be processed, or “canned” by boiling the water. Low-acid meats and vegetables must be processed using an industrial pressure canner that is set at 121 degrees Celsius (15 PSI pressure).
  • Tin-coated steel containers are frequently used. They are followed by glass containers.
  • Today, containers made of aluminum and plastics, in the form of rigid containers or pouches are becoming more popular.
  • Some examples of food that is preserved through canning are: all kinds of canned foods including soup meat cereal grains, beans legumes, nuts, and different dried food items such as coffee, fruits milk, soups meat, fish and vegetables.

Steps of Canning

The most common steps used for canning food include cleaning blanching, filling sealing, exhausting cooling, labeling and cooling.

  1. Cleaning: This is the very first step of the process of canning. A thorough cleaning of the product to be canned can help get rid of most spoilage-causing organisms.
  2. Blanching: This procedure can be used to add a warm water rinse. It removes food enzymes and helps to preserve the natural color in the products. It also softens fibrous plant tissues and assists in the elimination of skin. The food ingredient is submerged into hot liquid or exposed to steam for between 2 and 5 minutes before being afterward, dipped in cold water to avoid further exposure to the heat.
  1. Filling: Filling can be done either manually or using machinery, the contents are filled into cans. The headspace should be 6-9mm above the food level inside the can has to be left.
  2. Exhausting: Gases are emitted through the container containing contents through an exhaust box which hot steam or water is utilized. The food is expanded and then expels gases and air from food items and the head space of the can.
  3. Sealing: The contaminated contain-ers are sealed immediately to prevent the possibility of contamination.
  4. Sterilization: In order to bring about complete sterilization, a thermal treatment is used. This will ensure the destruction of spoilage microorganisms. This is typically done through the use of pressure-sensitive steam.
  5. Cooling: The containers are then quickly cooled to test the effect of heat and to prevent any excessive softening of food or alteration in colour of food. It is done with water or air.
  6. Labeling: The containers are labeled with the nutritional information of the food contained.

(d) Blanching

  • Blanching is a process of heating similar to pasteurization.
  • This is accomplished by submerging the product under boiling hot water for 2 to 3 minutes at temperatures ranging from 180degF to 190degF.
  • Blanching is focused on deaerating the product as well as activating enzymes that degrade before proceeding with process.
  • Blanching is a crucial process to freeze food, because frozen food can take on flavors, loss of vitamins and changes in colour during storage.

Advantages of Blanching

  • Stops the growth of bacterial.
  • Enhances vegetable’s natural color and keeps the color.
  • The product shrinks, which is better to fill the container.

3. Drying food preservation

  • Microorganisms require water to grow. If exposed to sunlight or exposed to dehydration the moisture present in the food is eliminated and the amount of water is reduced to a predetermined amount. This stops development of microorganisms, and thus causing food spoilage.
  • Drying food is among the oldest methods used from early times.
  • This process involves exposure of food items to the sun and air until the food is dry. It’s an extremely efficient and cost-effective method.
  • Drying and dehydration and ‘dehydration’ refer to the process of removing water.
  • Drying is the process of removing moisture through the use of alternative energy sources such as wind and sun.
  • Dehydration is the process of removing moisture through the application of artificial heat in controlled conditions of humidity, temperature as well as airflow.

Treatment of Foods Before Drying

  1. Selection and sorting based on size, maturity, and overall health
  2. Cleaning, particularly fruits and vegetables
  3. Peeling fruits and vegetables with a hand, machine, or knife
  4. Subdivide into halves, shreds, slices or cubes.
  5. Scalding or blanching of vegetable and certain fruits, such as peaches and tomatoes
  6. The sulphuration of light colored fruits and vegetables through exposure to sul-phur di-oxide gas.

Types of Dring Methods

1. Sun drying

  • Sun-drying absorbs sunlight’s heat, but it’s a lengthy process that is prone to spoilage and contamination.
  • The problem with sun drying is the availability of a climate that has a hot sun and dry climate.

2. Mechanical/ artificial drying

Artificial drying is the process of passing of hot air and controlled moisture over food items that is to be dried , or the passing of food items through the air. Nuts, fruits, vegetables fish, meat and fish can be preserved successfully using this method. The dehy-dration process uses artificial drying methods such as the spray drying process, vacuum drying freezing and drum drying are employed to dry food items. Although they are expensive as compared to natural sun drying but it is extremely hygienic quick and the results that are produced are uniform in colour due to the fact that temperature and humidity are maintained.

Different types of mechanical or artificial drying

  1. Spray drying: Eggs and milk are dried into a powder in spray dryers where it is then atomized before being sprays into steaming hot air or fast drying.
  • Foam mat drying: foam mat drying can be commercially used to preserve tomato and orange juice. In this method, a tiny portion of the edible sta-bilizer employed. The foam is then spread into thin layers and then dried in a hot steam of air. The product is separated into tiny particles upon cooling.
  • Drying via osmosis : osmo-sis occurs when the fish is salted heavily. In this instance the moisture is drained away from all cells. The water then bonds to the solute, making it unobtainable to microorganisms. In the process of osmotic dehydration, which is a method of this method involves partial dehydration of fruits via osmosis in sugar solution that is concen-trated or a syrup.
  • Freeze drying: Freeze drying is the process of removing water from frozen products by sublimation is referred to as freeze drying. Foods that are freeze dried are of high-quality with a soft and porous texture.

4. Preservation by Irradiation

  • The aim of irradiation to kill microorganisms and deactivate enzymes, without altering the nutritional content of the food.
  • Food irradiation is a low temperature sterilizing process. In this instance, sterilization can be accomplished at the temperature of room.
  • The food we eat is exposed to extremely high energy radiation known as gamma rays, or electrons that are fast moving, killing insects, fungi and bacteria.
  • In some instances radiation delays the ripening process of fruits.
  • The main benefit of Irradiation is that it is able to be carried out after food is sealed and packaged.
  • It has been utilized in pasteurizing or sterilizing perishable food items like fish, meat as well as fruits, and prolonging their shelf life for lengthy durations.
  • It can also be used for inhibiting the sprouting process in potatoes, onions, etc.
  • Cobalt-60 or Cesium-137 , also known as electrons-producing machines are primary sources of ionizing radiations employed for food irradiation.

Chemical Methods of Food Preservation

  1. High concentration of salt
  2. Pickling
  3. High concentration of sugar
  4. Using chemical preservatives

A. Salting 

  • It is a traditional preservation method. Food is processed using salt or a strong solution of salt. 
  • Salt can cause an increase in osmotic pressure as well as shrinking of cells, it also dehydrates food and microbes through the draw-out of water.

B. Pickling

  • It’s also an ancient preservation technique.
  • The preservation of vegetables and fruits with vinegar, salt oils and spices is known as picking.
  • A layer of oils floating over the top of the pickles blocks the growth and entry of microorganisms, such as yeast and moulds.
  • Spices such as chilli, pepper, turmeric powder, asafoetida and turmeric slow the development of bacteria.
  • Vinegar creates an acidic environment for the growth of microbes.
  • The added salt absorbs water and stops the growth of microorganisms.
  • Pickles make great appetizers. They are a nice addition to the food.
  • They aid digestion by stimulating the flow of gastric juices.
  • The nutritional value of pickles is contingent upon the raw material and the methods of preparation employed.
  • Raw mangoes and lemons, as well as amla ginger, garlic chilli, tomato mixed vegetables like potatoes, carrots beans, peas, and cauliflower are all used in the preparation of pickles.

Common Ingredients used for Pickling

  1. Salt: Salt is used to pickle. Salt must be free of lime (Ca CO3) because it lowers the acidity of vinegar that preserved vegetables get packed. Fruits and vegetables don’t develop when brined with a large amount of salt. Pickle spotting is prevented by adding enough regular salt
  2. Vinegar: Vinegar acts as preservative. In order to avoid the dilution of vinegar from the water ejected by tissues, tables are usually stored in strong wine-gar of around 10 percent acidity for several days prior to the process of picking.
  3. Sugar: Sugar is used for the making of sweet pickles must be of the highest quality. Sugar is helpful in the preservation of the products when it is employed.
  4. The spice mix: These are typically added to all pickles, but the amount of spice is determined by the type of fruit or vegetable consumed and the type of flavor that is desired. Common spices include dry chillies, cardamom clove, cinnamon coriander seeds, turmeric, mustard cumin and fenugreek seed. Spices like mint, ginger, garlic asafoetida, curry leaves and curry leaves are utilized. Spices are utilized either in fresh or the dry form.
  5. Water: Potable water is the only option to be used to prepare of brine. Hard water can interfere with the normal salt curdling of the vegetables.
  6. Coloring and Hardening Agents: Natural colouring agent turmeric is used extensively in sauces, pickles and the ketchups. Artificial colours are rarely added to pickles, even though they are they are permitted in certain limits. Sometimes, alum is used to add firmness to vegetables that are used in pickling.

Types of Pickles

There are five kinds of pickles like;

  1. Salt Pickles: The salt pickles add flavor to food and increases the digestion. The process of making it involves adding salt to the fruit and vegetable pieces, and then allowing it to soak.
  2. Spiced Pickle: spiced pickle variety of pickle tastes better because the addition of spices and oil for flavoring and preservation.
  3. lemon juice :Pickles preserved with lemon juice Garlic and vegetable pickles made from lime juice give a refreshing flavor.
  4. Vinegar Pickle: Vinegar is dilute acetic acids. Vinegar is used as a preservative for tomato sauces. It is also used to prepare chilli sauce, tomato pickle as well as meat pickle.
  5. Sweet Pickle: This sweet Pickle is made with sugar and garam masala to sweet vegetables. Fruits and vegetables should be submerged in sweet vinegar, then boiled for 5-6 minutes and then mixed well. It is then cooled and stored in the container.

C. High Concentration of Sugar

  • Sugar is able to bind water , making it inaccessible to microbial growth. 
  • It decreases the solubility of oxygen in mois-ture which is crucial to the development and proliferation of microorganisms. 
  • Guavas, apples, oranges and pineapples can be used to make Jellies and jams. The fruit must be perfect because the content of pectin is high in these fruits.

D. Using chemical preservatives

The compounds, when added, can disrupt the cell membrane of microorganisms, their enzyme activities or their genetic processes. They also function as antioxi-dants. The chemical preservatives commonly used are

  1. Benzoic acid (including benzoates): sodium benzoate is a benzoic acid salt and is used for preservation of colored fruit juices and squashes.
  2. Sulphur dioxide (including Sulphites): Potassium meta-bi-sulphite is used to create sulfur dioxide when added to juices or squash. When it is used in fruit that have deep colors, such as jamun, blue grapes and watermelon, it alters the colour, and in these cases, benzoic acid is a good choice.
  3. Organic acids as well as their salts: The preservation of food can take place by mixing lactic propionic, acetic, citric acids as well as their salts. Nitrates, nitrites and other compounds are used to preserve meat as well as fish products. It imparts desirable colour and flavor , and deters the growth of microorganisms. It also stops the formation of toxin by microorganisms that are present in food.

Harmful effects of food preservatives

  • Food preservatives are extremely helpful in the storage of food, but they aren’t effective for keeping healthy health.
  • There are numerous health issues due to preservatives like the nitrates and nitrites, which can be very beneficial in conserving meat and other products but most studies have shown that they cause carcinogenesis and can be very detrimental to our health.

Examples of preservatives used in food

Below are some examples of the various kinds of preservation agents:

  • Potassium Nitrate
  • Erythorbic Acid
  • Benzoic acid
  • Sodium Benzoate
  • Calcium Sorbate

Antioxidants serve to preserve food items by reducing the rate at which products can be spoiled. The most common examples are Butylated Hydroxyanisole (BHA), Butylated Hydroxytoluene (BHT) as well as Ascorbyl Palmitate.

  1. Antioxidants in Food Preservation: Antioxidants that are used in preservation of food come in two categories naturally occurring antioxidants and artificial antioxidants. Both are employed as food preservation agents. Oxidation is a major factor that affects the nutritional value of food items and can reduce its lifespan by drastically altering its appearance color, taste and nutritional quality.
  2. Common Antioxidants in Food Preservation: Common Antioxidants used in Food Preservation Some examples of antioxidants that are natural in food preservation and the source are the tocopherols (found in seeds and nuts) citric and ascorbic acid (found in the citrus fruit) as well as carotenoids (found in vegetables and fruits) as well as phenolic substances (found in spices and herbs such as the grape seed). Extracts of plants containing phenols can be widely employed for the preservation of meat, seafood fats, oils and other oils. Ascorbic acid is widely used for the preservation of jams, juices, cereals and treated meats as well as certain canned food items. In addition tocopherols can be utilized for the protection of meat, cereals, and poultry products as well as butter, oils and various dairy products. The extract of rosemary is used primarily as an antioxidant in all continents in Europe in addition to North America.
  3. Sodium Preservative In Food: Food Preservatives Using Sodium The most widely used salt-based preservative for foods is the sodium benzoate. Sodium benzoate is primarily regarded as a preservative that is used in processed food and drinks to prolong the life of drinks however it also has other applications. It is a odorless and crystalline powder made by mixing benzoic acid and sodium hydroxide. Another sodium preservative that is widely used for food products is sodium Nitrate. It is a preservative that is commonly used in processed meats, such as bacon and jerky, as well as luncheon meats. However, it can increase your risk of developing heart disease. It is believed that sodium nitrate could damage blood vessels, which makes your arteries more susceptible to become narrow and harden, which could lead to heart disease.
  4. The role of salt in food Preservation: Salt is a common an essential role in the fermentation process of food products. Fermentation is a typical process to preserve food items and fresh produce. It is a process whereby fresh fruits and vegetables become desirable foods which can be stored longer than their original purpose because of the actions of certain microbes. The most common perception of salt’s role in preservation of food is that it destroys bacteria, however in it to be true salt is not able to conserve food directly. Instead, it must play a vital role in the process of the process of osmosis. Salt is always able to play a role in the formation of physical properties of food which are useful for manufacturing or enhancing the final quality of the product. For instance, the levels of salt are a major factor in helping manage the adhesion properties of certain doughs, which are the basis of certain baked products. Salt is a key role in the formation of the physical properties of food that benefit the process and the progression of the final quality of the product. For instance salt levels play a crucial part in regulating the stickiness certain doughs that ease the process of baking ingredients.

Preservation by Fermentation

  • Fermentation is among the traditional methods for preserving food.
  • Fermentation prolongs the shelf-life of food items, like drying and salting.
  • The term”flourescence” refers to both aerobic and anaerobic breakdowns that occur in car-bohydrates and carbohydrate like Mate-rials.
  • Fermentation is a process that encourages multiple microorganisms, and their metabolic functions are also boosted as opposed to other methods of preservation. In thisway, microorganisms breakdown complex organic compounds into simpler compounds when they are in anaerobic or aerobic conditions.
  • The chemicals created by microorganisms, such as acid or alcohol cause the preservative effects of fermentation through slowing down spoilage-related factors.
  • The most important chemical compounds involved are the acids (especially the acid lactic) as well as alcohol. They inhibit the growth of the common pathogenic bacteria in food.
  • Some examples of food that is preserved by fermentation include alcohol products (e.g. beer, beer or fruit wine) as well as acid products (e.g. vinegar or pickled vegetables) such as yogurt, cheese, etc. This method is usually coupled with pasteurization.

Types of Fermentation

  1. Anaerobic conditions: In pro-duction of cheese, due to Streptococcus lactis bacteria the enzyme lactose converts to lactic acid in an anaerobic state.
  2. Aerobic condition: in the production of vinegar because of Acetobacter bacteria, ethyl Alcohol is converted to acetic acid in an aerobic state.

Foods Produced by Fermentation

1. Alcoholic Beverages

  • Wine: Yeast is found on the grape’s skin. The fermentation process begins when yeast reacts with sugars from grapes, converting the sugars into alcohol.
  • Beer and Ale: They contain malted cere-als, which are fermented by yeast and produce 37% alcohol. The yeast type as well as the quan-tity of the yeast and the fermentation temperature determine the amount of alcohol produced.

2. Vinegar Preparation

  • With oxygen, Acetobacter bacteria transform alcohol into Acetic acid. Vinegar can be made using carbohydrate sources such as fruits and cereals.

3. Cheese Production

  • Streptococcus lactis bacteria converts the sugar in milk into the acid lactic. The acid curdles milk and turns it into cheese.

4. Citric acid Production

Citric acid is derived from mould, yeast, and the bacte-ria. It is utilized to make fruit drinks.

Uses of Fermentation

  • Fermentation can extend the shelf life of food items.
  • It increases the growth of microorganisms which produce alcohol and acid.
  • It stops development of lipolytic as well as proteolytic microorganisms.
  • Vinegar that is made by fermentation is of industrial significance.

Combination of Two or More of the Above methods or Hurdle Technology

  • Hurdle or barrier concepts are founded on synergistic effects of preservatives as well as other methods to preserve food.
  • Food hazard is defined as the ingredient or the process or a variety of preservation factors hindering the growth of different microorganisms that cause dying microorganisms.
  • The higher the hurdle, the greater is the impact.
  • The measurement of different factors with respect to pH redox-potential temperature, water activity and preservatives, etc. determines the level of success combinations of obstacles that result in the failure of growth and, ultimately, deaths of bacteria.
  • Hurdle technology is a great way to provide food products that are shelf-stable that is of superior quality and fresh characters.

What is Carbonation?

Carbonation is the method by where carbon dioxide dissolves inside food products under pressure. The premise behind this is that, by removing oxygen from the atmosphere, carbon dioxide impedes the growth of bacteria. E.g. carbonated drinks (soft drinks) are, therefore, containing an organic preservative.

Scope of Food Preservation

Food preservation stops the loss and waste of nutrients in food products and lets people take advantage of the nutrients concentrated food items. A significant reduction in spoilage and waste of perishable food products boosts the economic growth of the country by providing more food to people at reasonable costs. It also provides needed jobs to a lot of people working in food processing and related fields. Due to the rapid the growth of food preservation industry the need for qualified personnel has increased significantly. In light of the recent liberalization program and removal of trade restrictions There is an enormous opportunity for exports of processed food items. Multinational food companies are seeing India as a potential market. If Indian products meet international standards for quality and succeed in competition, we could make money from foreign exchange.

Advantages of Food Preservation

There are several advantages to food preservation. These include:

  • longer shelf life,
  • fewer pathogen risks,
  • less spoilage (enzymatic, microbial),
  • the elimination of anti-nutritional factors, year-round availability of seasonal foods,
  • perishable goods that can be transported over long distances,
  • greater availability of convenience food (such as instant mixes), and
  • enhanced sensory and nutritional features.
  • Preservation can also produce foods of different sorts, which are important in several cuisines. For example, raisins, squashes, and grape wines.

FAQ

What are the different methods of food preservation?

Preservation by low temperatures
Preservation by high temperature
Preservation by drying
Preservation by irradiation
High concentration of salt
Pickling
High concentration of sugar
Using chemical preservatives

Which methods of food preservation would you use?
(a) Drying the food grains from farms under the hot sun is called dehydration.
(b) Materials like milk are instantly cooled after heating up to a certain high temperature.

Ans: (a) Drying the food grains from farms under the hot sun is called dehydration.

References

  • García-García, R., & Searle, S. S. (2016). Preservatives: Food Use. Encyclopedia of Food and Health, 505–509. doi:10.1016/b978-0-12-384947-2.00568-7 
  • Surekha, M., & Reddy, S. M. (2014). PRESERVATIVES | Classification and Properties. Encyclopedia of Food Microbiology, 69–75. doi:10.1016/b978-0-12-384730-0.00257-3 
  • https://www.brainkart.com/article/Methods-of-Food-Preservation_35169/
  • https://biologyreader.com/food-preservation-techniques.html
  • https://www.reagent.co.uk/chemical-methods-of-food-preservation/
  • https://unacademy.com/content/kerala-psc/study-material/food-microbiology/food-preservation-physical-and-chemical-methods-of-preservation/
  • https://www.vedantu.com/chemistry/chemicals-used-as-food-preservatives
microbiology note app
microbiology note app qr code Scane to download
Download Microbiology Note App Download this app for free from google play store and read ads free notes
Need a Note? Request us
Request
0

Leave a Reply

Your email address will not be published. Required fields are marked *

0
Follow
X

Follow

E-mail :*
* Your personal data will be used to support your experience throughout this website and for other purposes described in our Privacy Policy. I hereby agree and consent to the privacy policy.

Microbiology Notes is an educational niche blog related to microbiology (bacteriology, virology, parasitology, mycology, immunology, molecular biology, biochemistry, etc.) and different branches of biology.

More From Microbiology

Ads Blocker Image Powered by Code Help Pro

Ads Blocker Detected!!!

We have detected that you are using extensions to block ads. Please support us by disabling these ads blocker.