6c. Food Processing - Plant products

Food Processing and Preservation: Overview

• Focus on plant products including oils, grains, and fruit and vegetable products.

• Important to understand the sequence of production steps for:

  • Oils

  • Pasta and grain products

  • Fruit and vegetable products (frozen vegetables, apple juice)

• Key differentiation in wheat types and their uses in the food industry.

Oil Production Process

Steps in Processing Vegetable Oils

1. Cleaning

   • Screening: Sifting seeds/kernels to remove debris.

   • Aspiration: Vacuuming to eliminate dirt and dust.

2. Grinding/Cracking

   • Breaking the hull to access the oil content within the seed/kernel.

3. Steaming/Cooking

   • Soft thermal treatment to aid in oil release from the cell structure, making seeds more pliable for flaking.

4. Flaking

   • Pressing seeds into flakes for better oil extraction.

   • Increases exposure of oil-containing cells.

5. Extraction

   • Addition of solvents to dissolve the oil while leaving solids and water behind.

6. Separating

   • Utilizing pressing and/or centrifuging to extract oil from plant cells.

   • If solvents are used, they are separated from solids and water.

7. Removal of Solvents

   • Complete evaporation to obtain crude or unrefined oil, which may need further refining.

8. Refining Process

   • Deodorization: Steam application to remove odor-causing compounds.

   • Degumming: Removal of water-soluble phospholipids.

   • Bleaching: Removal of color-bearing substances.

   • Neutralizing: Eliminating free fatty acids.

   • Winterizing: Removal of triglycerides with high melting points.

9. Packaging

   • Packaging must consider oil characteristics to protect from light, metals, and heat.

Olive Oils

• Virgin and Extra-Virgin: Cold-pressed without excess heat or refining.

• Pure Olive Oils: Mixtures of virgin and refined oils.

• Color Variations:

  • Virgin olive oils are usually green-yellow.

  • Pure olive oils are pale green-yellow.

  • Light olive oils are pale yellow with lower color intensity.

Cereal Grain Processing

Wheat Processing for Pasta Making

• Different types of wheat:

  • Hard Wheat (Durum): High gluten content, suitable for pastas.

  • Soft Wheat: Low gluten, suitable for cakes and pastries.

• Gluten formation: Two protein fractions (gliadin and glutenin) combine in the presence of water to create a network.

Wheat Milling Process

1. Cracking the Kernel

   • To expose endosperm containing starch and protein.

2. Grinding

   • Producing coarse or fine flour from hard or soft wheat.

3. Sieving

   • Removing hull, bran, and germ to purify flour.

Pasta Processing Steps

1. Mixing

   • Combining semolina with water to form dough.

2. Extruding

   • Pressing dough through dies to shape pasta.

3. Cutting

   • Creating long strands of pasta.

4. Drying

   • Reducing moisture to improve preservation.

5. Packaging

   • Storing in boxes or bags at room temperature.

Fruit and Vegetable Processing

Initial Processing Steps

1. Trimming

   • Removing unwanted plant parts like stems and roots.

2. Cleaning

   • Washing with detergents; must be suitable for firm fruits and vegetables.

3. Blanching

   • Mild heat treatment to inactivate browning enzymes.

Vegetable Processing Example (Frozen Mixed Vegetables)

1. Peeling/Trimming/Cutting

   • Preparing vegetables for processing.

2. Washing

   • Ensuring cleanliness with mild detergent.

3. Blanching

   • Inactivating degradation enzymes.

4. Precooling

   • Lowering temperature before freezing.

5. Freezing

   • Using Individual Quick Freeze (IQF) method for rapid freezing.

Apple Juice Processing Steps

1. Skinning and Coring

   • Removing skins and seeds from apples.

2. Washing

   • Cleaning with mild detergent.

3. Juice Extraction

   • Crushing apples to recover juice.

4. Clarification

   • Adding pectinase to remove cloudiness.

5. Filtration

   • Removing pulp and small particles for clarity.

6. Pasteurization

   • Heat treatment to eliminate pathogens.

7. Packaging

   • Storing juice in cleaned and sanitized containers.