Untitled Quiz

Food Technology

• Food technology is the application of food science to the selection, preservation, processing, packaging, distribution, and use of safe, nutritious, and wholesome food.
• Food science is the discipline that uses biology, physical sciences, and engineering to study the nature of foods, the causes of their deterioration, and the principles underlying food processing.

Quality

• People choose foods based on factors in sum termed "quality."
• Quality is defined as excellence and includes taste, appearance, and nutritional content.
• Quality and price are not necessarily related.
• "Value" is thought of as a composite of cost and quality.
• Higher quality foods can be a good value if their quality is very high.
• The nutrient value of canned fruits and vegetables is similar across grades; however, prices may vary three-fold depending on quality attributes.
• Processors go to extremes to control quality.

Sensory Evaluation of Food Quality

• Physical senses, including sight, touch, smell, taste, and hearing, are used to evaluate food quality.
• Textural characteristics (e.g., snap of potato chip, crunch of celery) are also evaluated.
• Food quality, detectable by senses, is divided into three categories:
  • Appearance factors
  • Textural factors
  • Flavor factors

Additional Quality Factors

• Nutritional quality, sanitary quality, and keeping quality are important quality factors not always apparent by sensory observation.
• Nutritional quality can be assessed via chemical or instrumental analyses of specific nutrients.
• Sanitary quality is measured by counts of bacteria, yeast, mold, and insect fragments, as well as sediment levels.
• Keeping quality (or storage stability) is measured under storage and handling conditions designed to simulate or exceed normal distribution and use conditions.

Food Preservation and Storage

• Food is a basic necessity for life and is often seasonal, spoiling quickly.
• Food undergoes deterioration (spoilage) from harvest/slaughter/manufacturing.
• Preservation methods are needed to prevent spoilage and maintain nutritional value, reduce toxic substances. and extend shelf-life.
• Knowledge of processing and preservation is essential to extend shelf life whilst minimising loss of nutritive value.

Definition of Food Storage

• Food storage is the process of storing cooked and raw materials under appropriate conditions for future use without microbial entry or multiplication.

Types of Food Storage

• Dry storage, usually at room temperature (20-25°C) with 60-65% humidity is for non-perishable/semi-perishable foods.
• Low-temperature storage, which can be further divided into:
  • Refrigerated storage (3-10°C) is for short-term storage of perishable foods.
  • Cold storage (0-3°C) for longer-term storage of fruits and vegetables
  • Freezer storage (-20°C to 0°C) for long-term preservation

Essential features of food storage areas

• Storage areas must be suitable for the type of food (e.g., dry store, chill, frozen).
• Separate areas should be designated for different types of food (e.g., raw and cooked).
• Storage areas must be weatherproof and protected from contamination.
• They must keep away direct sunlight and heat, and have appropriate ventilation.
• Storage areas must be easily cleanable and accessible for transport.

Table 1: Storage Life of Some Foods

• Presents storage life (days at 21°C) for various food products (e.g., raw beef, raw poultry, dried meat, fresh fruits).

Definition of Food Preservation

• Food preservation is the science of preventing food decay or spoilage, allowing storage for future use.
• Microorganisms contribute to spoilage, with some beneficial bacteria (e.g., in cheese, wine).
• Preserving food helps maintain quality, edibility, and nutritive value.

Importance of Food Preservation

• Food preservation is crucial to human existence and civilization.
• Delaying fresh foods' processing alters freshness, color, texture, palatability, nutritional value, organoleptic desirability, aesthetic appeal and food safety.

Need for Food Preservation

• Preservation allows for the availability of foods throughout the year, especially those harvested during a limited season.
• It helps prevent food wastage.
• Preservation often lowers food costs and contributes to equal access at all times across all regions and environments.

Methods of Food Preservation

• Prevent microbial growth (bacteria, fungi, etc.).
• Inhibit oxidation of fats ("rancidification").
• Prevent enzymatic browning.
• Apply heat treatment (e.g., canning).
• Drying, spray drying, freeze drying, freezing, vacuum packing, adding preservatives (e.g., carbon dioxide), food irradiation.
• Other methods include pickling, salting, smoking, preservation in sugar syrup and curing.

Food Spoilage

• Healthy foods resist infection and microbial growth under ideal conditions.
• Several causes of spoilage include poor sanitation, enzymes, chemical reactions, improper temperature control, microbial growth.
• Physical changes arise from bruising, puncturing, and water loss.
• Chemical changes due to enzymes or microbial growth lead to undesirable alterations.

Major Reasons for Food Rejection as Spoiled

• Organoleptic changes (due to microbial growth).
• Chemical changes (e.g., oxidative rancidity, browning of fruits/vegetables).
• Physical changes (e.g., burning, drying, freezer burn).
• Staling (due to change in water content).
• Overripening
• Contamination with chemical agents (e.g., sanitizers).
• Spoilage due to Microorganisms and Insects.

Factors Affecting Food Spoilage

• Food composition influences susceptibility to spoilage (e.g., proteins, carbohydrates preferred by microbes).
• Food structure affects sterilisation (e.g., skin, rind protect).
• Types of spoilage microorganisms present.
• Storage conditions (e.g., temperature, humidity) dramatically affect microbial growth.

Classification of Foods by Ease of Spoilage

• Foods are classified into three groups based on their spoilage rates:
  • Non-perishable (stable) foods (e.g., grains, flour, sugar).
  • Semi-perishable foods (e.g., potatoes, apples).
  • Perishable foods (e.g., milk, meat, fish).

Causes of Food Spoilage

1. Biological causes: Growth and activity of microorganisms (bacteria, yeasts, molds), enzyme activity and damage from pests.
2. Chemical causes: Reaction with oxygen and light, chemical reactions within food components.
3. Physical causes: Temperature changes, physical abuse, freezing, burning, drying, pressure

Food Poisoning vs. Food Spoilage

• Food poisoning is a result of consuming contaminated food (microbial or chemical), leading to illness.
• Food spoilage affects food quality and reduces safety.
• Both affect human health and profitability of food industry.

Factors Affecting the Development of Microorganisms in Foods

• Intrinsic factors (inherent in the food):

  • Nutrient content, pH, redox potential, water activity, antimicrobial constituents, biological structures.

• Extrinsic factors (external):

  • Temperature, relative humidity, gaseous atmosphere.

• Implicit factors:

  • Synergism, antagonism, commensalism, growth rate.

• Processing factors:

  • Irradiation, washing, slicing, pasteurization and packaging.

Moisture Content

• The amount of free water available affects microbial growth.
• Water activity (Aw) is the ratio of vapour pressure of a food to the vapour pressure of pure water.
• Lower water activity inhibits microbial growth.
• Preservation methods often include reducing water activity.

Redox Potential (Eh)

• Eh describes the tendency of a substance to lose or gain electrons.
• Positive Eh values support aerobic microorganisms, while negative Eh values support anaerobic microorganisms.
• Eh can be affected by oxygen availability and microbial activity.

Nutrients Content

• Microorganisms require water, carbon, nitrogen, minerals, vitamins and growth factors to live and grow.
• Presence of these nutrients in food materials influences microbial growth and spoilage.
• Different nutrients are preferred by different micro-organisms.

Antimicrobial Substances

• Various foods contain substances that inhibit microbial growth (e.g., essential oils in spices, antimicrobial proteins in milk, egg).
• These substances prevent microbial attack (infection).

Biological Structures

• Some foods possess biological barriers that hinder microbial entry (e.g., skin and fascia in meat, egg shell/membranes).
• These structures prevent microbial infection.

Extrinsic Factors

• Extrinsic factors to the food refer to external factors that influence microbial growth.
  • Temperature of storage
  • Presence and concentration of gases in the environment
  • Relative Humidity of food storage environment

Temperature

• Microbial growth is influenced by temperature.
• Different microorganisms have optimal temperatures for growth.

Concentration of Gases in the Environment

• Oxygen tension affects microbial growth:
  • Aerobic needs high levels
  • Anaerobic avoid oxygen
  • Facultative can survive with or without oxygen

Relative Humidity

• Relative humidity refers to the amount of moisture in the air surrounding the food.
• High relative humidity can increase spoilage due to high moisture content.