Overview of food processing

Overview of Food Processing

NOTE

FOOD PROCESSING

Enhances food safety, shelf life, nutritional value, and convenience.

Food processing involves transforming raw ingredients into consumable food through physical, chemical, or biological means.

GENERAL REASONS FOR FOOD PROCESSING:

• Elimination of Pathogens
• Preservation
• Enhanced Nutritional Quality
• Improved Sensory Attributes (color,flavor, taste, texture, smell)
• Special Dietary needs
• New products
• Waste Reduction

FOOD PROCESSING

Stages of Food ProcessingPrimary Processing: Converting raw materials into basic food products (e.g., milling grain, slaughtering animals) Secondary Processing: Transforming primary products into finished food items (e.g., baking bread, canning fruits)

Common Food Processing Methods Thermal Processing: Pasteurization, sterilization, blanching, drying, smoking, roasting, baking, frying Non-thermal Processing: Refrigeration, freezing, irradiation, high pressure processing, pulsed electric field, osmotic dehydration Other Methods: Fermentation, filtration, centrifugation, extraction

IRRADIATION

DEHYDRATION

PASTEURIZATION

USE OF HIGH TEMPERATURES

STERILIZATION

NATURAL

USE OF LOW TEMPERATURES

FREEZING

REFRIGERATION

Food Preservation Methods

CHEMICAL

USE OF SUGAR OR SALT

USE OF ADDITIVES

FERMENTATION

USE OF USEFUL MICROORGANISMS

BIOLOGICAL

FOOD PROCESSING METHODS CLASSIFICATION BASED ON THEIR ACTION

Refrigeration is the method of preserving food at temperatures around 0 degrees Celsius and a little above the temperature at which the water in the food begins to freeze--> the product does not freeze.The duration of food preservation under refrigeration depends on many factors. The most important are: • The type of food • The conditions of rstoring.

Benefits: Convenient, affordable, maintains freshness. Challenges: Limited shelf life compared to freezing, may not be suitable for all foods.

Refrigeration/Cooling

Common practice in:

• all homes in the household refrigerator, where a wide variety of fresh and processed foods are kept.
• industrial refrigeration facilities, before fresh products (fruits, vegetables, meat) are taken for consumption, processing of processed products (pasteurized milk, yogurts, cheeses, juices, etc.) until their consumption

When preserving food under refrigeration, the following must be checked:

• The storage temperature
• The relative humidity of the storage chamber
• The composition of the chamber atmosphere

Refrigeration helps keep foods at safe temperatures, reducing the risk of foodborne illnesses by inhibiting the growth of harmful pathogens.

FREEZING

The quality of frozen food depends on:

• the size,
• the location and the number of ice crystals
• speed of theadapted process

Food freezing is a food preservation process based on exposing food to temperatures below its freezing point, a point at which the state of matter changes and the properties of the product are altered, turning it into ice and solidifying all the water or moisture contained in the food. Normally this point is between -18ºC and -35ºC, although this will depend on the type of product to be frozen. The purpose of this process is to eliminate all activity of micro-organisms or bacteria in the food without significantly altering its nutritional content, and thus its spoilage. In addition, freezing significantly reduces chemical and enzymatic activity, such as oxidation of the food.

TYPES OF FREEZING: Slow: this is the most common case and is used for domestic use or large freezing chambers. Medium: it is carried out with cold air tunnels at temperatures down to -40ºC. Fast: mainly used in the industrial and professional field, it consists of abrupt temperature changes achieving thermal stabilisation around -18ºC.

By rapidly lowering temperatures, freezing halts bacterial growth, preserving flavor and nutrients of fruits, vegetables, and meats. Benefits: Long shelf life, excellent for retaining nutrients. Challenges: Can alter texture, requires special equipment.

DRTING

Drying, one of the oldest food preservation techniques, removes moisture from food through evaporation. This creates a hostile environment for bacteria and mold, extending shelf life significantly. From sun-dried tomatoes to dehydrated fruits and jerky, drying concentrates flavors while preserving nutrients like vitamins and minerals. However, drying can alter texture and requires careful attention to prevent spoilage during the process.

Mechanical drying It is done either by exposing the product to a stream of hot air that gradually removes its moisture or by contact with a heated metal surface

Sun drying (e.g. raisins, figs) Disadvantage: -unpredictable weather, contamination from exposure to air, animals, etc. affect the process and the quality of the product - Requires a large area of ​​land - loss of sugars

Use by humans and nature (nuts, cereals and legumes = in a dry state at harvest).

FERMENTATION

A significant loss of nutrients, especially heat-labile vitamins, may occur during the canning process.

The main methods of heat treatment of food are pasteurization and sterilization.

Pasteurization is a mild heat treatment (below 100° C)--> small physicochemical changes in the ingredients of the food.This mild heat treatment destroys harmful pathogens in liquid foods like milk and juice, without compromising taste or nutritional value. Benefits: Enhances food safety, widely used and accepted. Challenges: May slightly alter taste, doesn't completely eliminate all bacteria. Sterilization refers to intense forms of high heat (121°C) or pressure treatment, which aim to destroy all microorganisms present in a foods, ensuring long-term shelf life for canned foods and medical supplies.With sterilization, greater changes are caused in the ingredients of the food. Benefits: Long shelf life, excellent for food safety. Challenges: Can significantly alter flavor and texture, may reduce some nutrients.

NOTE

The time and temperature required for the sterilization of foods are influenced by several factors, including the type of microorganisms found on the food, the size of the container, the acidity or pH of the food, and the method of heating.

Irradiation:Low-dose radiation kills bacteria and pests in foods like spices and grains, without affecting taste or nutritional value. Benefits: Enhances food safety, reduces spoilage. Challenges: Public perception concerns, limited availability in some regions.

While sugar is another one powerful preservative, there are some limitations: Sugar Rush for Microbes: Some molds and yeasts can actually thrive in high sugar environments. Finding the right sugar concentration is crucial to ensure preservation. Nutritional Considerations: Excessive sugar intake can contribute to health problems. Striking a balance between sweetness and preservation is important.

Food processing with added sugar - salt

By adding sugar or salt in high concentrations, the available water is reduced --> microbial growth by dehydration and osmosis. Osmosis and dehydration help in inserting salt and sugar molecules inside the food--> food preservation is ensured. Salt, a simple mineral, has been a champion of food preservation for millennia. While salting delivers a double whammy of preservation and flavor, it's not without its challenges: Sodium Content: The main concern is the high sodium content associated with salting. Excessive salt intake can contribute to health problems like high blood pressure. Finding a balance between preservation, flavor, and health is crucial. Texture Changes: Salting can alter the texture of food, making it firmer or drier. For some foods, like fish and jerky, this is a desirable effect, but it might not be suitable for all applications.

The Dehydrating Effect: By drawing out water, sugar creates a dehydrated environment within the food. This dehydration makes it difficult for bacteria and mold to survive and reproduce. This "osmotic stress" inhibits their growth, extending the shelf life of the food.