Food Technology in Halal Food Production

Introduction to Food Technology and Food Processing

  • Food Technology: A branch of food science addressing the production, preservation, quality control, and research and development (R&D) of food products. It is the scientific application of knowledge and techniques to improve food processing, preservation, packaging, quality, and safety. For example, food technology develops the knowledge of how heat destroys microbes.

  • Food Processing: The application of physical, chemical, or biological methods to convert raw materials into safe, edible, and convenient food products. It improves safety, shelf life, quality, taste, and availability. Processing ranges from simple actions (washing, cutting) to advanced methods (pasteurization, drying, extrusion). For example, food processing applies technological knowledge by pasteurizing milk.

Levels of Food Processing

  • Primary Food Processing:     - Definition: Basic processing of raw agricultural materials into edible or usable ingredients.     - Purpose: Prepare raw materials for direct consumption or further processing.     - Examples: Milling wheat into flour, pasteurizing milk, slaughtering meat, cleaning rice, extracting oil.     - Representative Transition: Wheat $\rightarrow$ Flour.

  • Secondary Food Processing:     - Definition: Further processing of primary ingredients into finished or value-added food products.     - Purpose: Improve convenience, taste, variety, shelf life, and market value.     - Examples: Bread made from flour, yogurt from milk, sausages from meat, noodles from wheat flour, biscuits.     - Representative Transition: Flour $\rightarrow$ Bread.

Classification of Food Processing Methods

  • Chemical Processing: Uses chemical changes to preserve food or improve safety.     - Chemical Preservatives: Sodium benzoate, sorbate, nitrite.     - pH Controlling: Adding vinegar or citric acid. Lowering pHpH slows microbial growth (e.g., pickles, sauces, soft drinks).

  • Biological Processing: Uses microorganisms or enzymes.     - Fermentation: Microbes convert sugars into acid, alcohol, or gas. One of the oldest processing methods.     - Products: Yogurt, tempeh, kimchi, bread.

  • Physical Processing: The largest industrial category, involving the use of heat, cold, drying, radiation, and packaging.     - Thermal Processing:         - Pasteurizing (HTST: High Temperature Short Time; LTLT: Low Temperature Long Time).         - Retorting, Aseptic Processing, Sterilization.     - Cold Treatment: Freezing, Refrigeration, Chilling.     - Drying: Dehydration methods.     - Non-thermal Processing: Irradiation, Ultraviolet (UV) Radiation.     - Hurdle Technology: Combining multiple preservation methods (e.g., semi-aseptic).

Fundamentals of Food Preservation

  • Causes of Food Spoilage: Microorganisms, Enzymes, Oxidation, Moisture, and Physical damage.

  • Objectives of Food Preservation:     - To suit human lifestyles.     - To extend shelf life.     - To increase variety in the diet.     - To make seasonal foods available year-round.     - To prepare food for chilled or frozen storage or ambient temperature stability.     - To allow time for distribution, retail, and home storage.     - To inhibit microbiological or biochemical changes.

  • Definition of Preservation: The process of applying methods to prevent or delay spoilage, maintain safety, quality, and nutritional value, and extend shelf life.

Preservation Technology: Physical Methods

Drying
  • Definition: Removing water to inhibit the growth of bacteria, yeasts, and molds.
  • Benefits: Extends shelf life, reduces weight, takes less storage space, lowers transportation costs, and is easy to handle.
  • Examples: Dried fish, dried fruits, milk powder, coffee, soup powder, cereal products.
  • Factors Affecting Drying Rate:     1. Surface Area: Smaller pieces dry faster.     2. Temperature: Higher temperatures increase the rate.     3. Humidity: Lower humidity speeds up drying.     4. Pressure: Lower pressure allows faster evaporation.
  • The Drying Process: Water is removed quickly from the surface at the beginning. As a dried layer forms on the outside, moisture remains confined at the center. Later, drying slows as moisture must move from the center to the surface.
  • Important Controls: Maintain constant temperature and good airflow. Excessive heat can cause case hardening (dry outside, moist inside), leaving the food vulnerable to internal spoilage.
Specific Drying Methods
  • Sun Drying: Uses direct sunlight for 3−43-4 days. Low cost but slow and weather-dependent. Risks include contamination by dust, insects, rodents, or birds. Ideal for high sugar, salt, or acid foods (raisins, salted fish).
  • Food Dehydrator: Electrical appliance using controlled heat and airflow. Faster, cleaner, and more efficient than sun drying; produces uniform quality.
  • Oven Drying: Household ovens used below 90∘C90^\circ\text{C} (200∘F200^\circ\text{F}). Slower than a dehydrator due to weaker airflow.
  • Room Drying: Indoor drying in well-ventilated rooms on racks/hangers; suitable for herbs/spices.
  • Freeze Drying (Lyophilization): Food is frozen, then water is removed via sublimation (ice directly to vapor under vacuum). Retains shape, color, flavor, and nutrients. Used for instant coffee and emergency foods. Excellent quality but high cost.
  • Spray Drying: Liquid or slurry is atomized into fine droplets in a hot air chamber. Rapid evaporation produces dry powder. Common for milk, coffee, egg, and infant formula. Not suitable for chunky or extremely heat-sensitive solid foods.
Chilling and Freezing
  • Chilling: Cooling food to slow bacterial action. Refrigerator temperatures typically range from 4∘C4^\circ\text{C} to 7∘C7^\circ\text{C}. Refrigeration does not kill microbes or inactivate enzymes; it only slows their effects.
  • Freezing: Slows decomposition by turning moisture into ice, rendering water unavailable for bacteria (dormancy).     - Freezing Point: Pure water freezes at 0∘C0^\circ\text{C}, but food freezes below 0∘C0^\circ\text{C} due to solutes (sugars, salts).     - Storage: Frozen food is preserved at −18∘C-18^\circ\text{C} or below for months.     - Freezer Burn: A problem where moisture loss or ice evaporation creates grainy, brownish, dry, and tough spots on the food surface.

Thermal Processing and Heat Treatment

  • Heat Treatment: Supplying heat to reduce the survival of microbes or enzymes to an acceptably low level.
  • Primary Target: Clostridium botulinum:     - Characteristics: Strictly anaerobic, Gram-negative, spore-forming (spores stable at 100−105∘C100-105^\circ\text{C}).     - Lethality: Produces a neurotoxin where 75 ng75\,ng can kill a human.     - Tolerance: Survives at pH>4.8pH > 4.8 and aw>0.85a_w > 0.85.
Factors Affecting Heat Treatment
  1. Microorganism Profile: Different species have different resistance; higher populations require longer heating. Spores are more resistant than vegetative cells.
  2. Food Components: Microbes are MORE resistant in fats, oils, protein media, and high sugar concentrations. They are LESS resistant in salt solutions (C.botulinumC. botulinum is inhibited at 8% NaCl8\%\,NaCl) and essential oils.
  3. pHpH of Food Product:     - Low-acid foods (pH>4.5pH > 4.5): Meat, seafood, milk, vegetables. Requires sterilization by retort.     - Medium-acid foods (pHpH 3.73.7 to 4.54.5): Tomatoes, pears, oranges. Sterilized by boiling water.     - High-acid foods (pH<3.7pH < 3.7): Pickles, pineapple, lemon juice. Sterilized by boiling water.
  4. Heating Conditions: Depends on heating medium (steam, hot water, flame), equipment (stationary, rotary), and operation type (batch vs. continuous).
  5. Container Size and Type: Cans, jars, pouches, or bottles. Larger cans require longer times to reach the center.
The Cold Point
  • Definition: The zone within a container that heats the slowest; the temperature here increases more slowly than the heating medium. It is measured using a thermocouple.
  • Location:     - Conductive heating: Geometric center of the container.     - Convective heating: Approximately one-third up from the base of the container.
  • Importance: Thermal processing must ensure the cold point reaches the established time/temperature relationship to eliminate resistant pathogens while retaining nutrients.

Specialized Thermal Methods

Canning
  • Process: Food is sealed in airtight containers and heated.
  • Steps: Raw material selection $\rightarrow$ Cleaning $\rightarrow$ Preparation (Blanching/Cutting) $\rightarrow$ Filling (adding brine/syrup) $\rightarrow$ Exhausting (removing air) $\rightarrow$ Sealing $\rightarrow$ Retorting (Sterilization) $\rightarrow$ Cooling $\rightarrow$ Labeling.
  • Methods: Water bath canning (pH<4.6pH < 4.6) or Pressure canning (pH>4.6pH > 4.6).
Pasteurization
  • Definition: A mild heat treatment to reduce harmful and spoilage microorganisms while maintaining flavor and nutrients better than sterilization.
  • Methods:     - LTLT (Low Temperature Long Time): 63∘C63^\circ\text{C} for 30 min30\,min.     - HTST (High Temperature Short Time): 72∘C72^\circ\text{C} for 15 sec15\,sec.     - UHT (Ultra High Temperature): 135−150∘C135-150^\circ\text{C} for 1−5 sec1-5\,sec.
  • Note: It does not completely sterilize; many products require subsequent refrigeration.
Retort Processing
  • Food in sealed containers is heated under high pressure and temperature (115−121∘C115-121^\circ\text{C} or higher). It achieves commercial sterility and allows room-temperature storage.

Chemical and Bio-Physical Preservation

Smoking
  • Mechanism: Exposes food to smoke from burning wood. It reduces moisture, provides antimicrobial compounds, and contains antioxidants to prevent rancidity.
  • Types:     - Cold Smoking: Lower temperature, primarily for flavor; usually requires further cooking.     - Hot Smoking: Higher temperature; cooks and smokes simultaneously.     - Liquid Smoke: Purified smoke flavoring applied as a liquid.
  • Halal Note: The process is physical, but the food source, curing ingredients, and shared equipment must be Halal-compliant.
Osmoanabiosis (Salting and Sugaring)
  • Principle: Making water unavailable to microbes by increasing solute concentration.
  • Key Terms:     - Anabiosis: Caused by drying.     - Osmo: Osmosis.     - Free Water: Available for microbial growth.     - Bound Water: Attached to food components; unavailable to microbes.
  • Osmosis Process: Movement of water through a semi-permeable membrane from lower to higher concentration. In high salt/sugar environments, water flows out of microbial cells.
  • Plasmolysis: The microbial cell shrinks due to water loss, stopping or slowing growth.
Pickling
  • Definition: Preservation in an acidic solution or via natural fermentation acid.
  • Main Preservative: Vinegar (acetic acid), lactic acid, salt, or sugar.
  • Types:     1. Vinegar Pickling: Direct preservation in vinegar (e.g., pickled onions). Faster.     2. Fermented Pickling: Natural bacteria produce lactic acid (e.g., kimchi, sauerkraut). Slower.