FDSCI 305 Final Exam 3

Fermentation

Microbial biotech where natural, renewable substrates are converted into value-added products.

Energy production in fermentation

During fermentation, cells produce energy via glycolysis through substrate-level phosphorylation.

Chemical Recycling

To maintain this cycle, NADH is recycled back into NAD+.

Sensory Improvement

Enhance the taste, aroma, texture of food.

Preservation

Increases the shelf-life of products.

Nutrition enhancement

Enhances overall nutritional value.

Enzymes

Proteins produced by living organisms that act as catalysts for specific biochemical reactions.

Scope of enzymes

Involved in the production of over 500 commercial products.

Direct acidification

Acidifies on its own, add something directly to product to acidify.

Rennet

Calf stomach enzyme, can be made in lab.

Lipases

Used in infant formula to increase palmitic acid proportion.

Amylases

Enzymes that break down starch, used in baking and brewing.

Pectin Enzymes

Used to clarify fruit juice.

Proteases

Used in baking to modify wheat gluten.

Oxidoreductases

Enzymes that affect taste, texture, shelf-life, appearance, and nutrition.

Successful fermentation

Depends on culture media and environmental conditions.

Common carbohydrate sources for cultures

Glucose, fructose, sucrose, starch, corn syrup, beet molasses.

Nitrogen sources

Required for protein synthesis; sources include ammonia, ammonium salts, proteins, peptone, and yeast.

Psychrophile

Microorganism that grows at temperatures less than 20°C.

Mesophile

Microorganism that grows at temperatures between 20-45°C.

Thermophile

Microorganism that grows at temperatures greater than 45°C.

Batch processing

Processing in a single, closed volume.

Fed-batch processing

Nutrients are added incrementally during the process.

Continuous processing

Substrates are added and products removed at a constant rate.

Immobilized Cell

Cells are fixed to a support to improve efficiency and reuse.

Lactic acid bacteria (LAB)

Central to dairy fermentation, ferment lactose to produce lactic acid.

Yogurt cultures

S. thermophilus and L. bulgarius.

Sodium nitrite

Changes meat color to bright pink.

Packaging

Protection of materials or goods in a container to prevent damage.

Primary packaging

In direct contact with food; performs most packaging functions.

Secondary packaging

Contains/protects primary package.

Tertiary packaging

Distribution package, often corrugated box holding multiple secondary packages.

Consumer packaging

Destined for final consumer; includes primary and secondary packaging.

Paper

Thin sheet from matted wood pulp; most common packaging material.

Metal packaging

Common metals include steel, aluminum, tin, and chromium-based materials.

Glass packaging

Soda-lime glass composition includes silica sand, soda ash, limestone, alumina, plus colorants.

Soda-lime glass composition

Silica sand, soda ash, limestone, alumina, plus colorants.

Formation of glass containers

Gob of molten glass blown or pressed into shape; threaded top formed while hot; containers annealed to relieve stress.

Advantages of glass packaging

Chemically inert; non-permeable; strong; resists high internal pressure; excellent optical properties; smooth surface.

Disadvantages of glass packaging

Fragile and brittle; heavy.

Thermoplastics

Synthetic or modified natural polymers that soften repeatedly on heating and harden on cooling.

Compression molding

Presses resin into heated mold.

Extrusion

Powdered resin fed into screw extruder and forced through a die.

Thermoforming

Plastic sheet heated and shaped.

Injection molding

Molten resin injected into closed mold and cooled.

Blow molding

Partially formed piece placed in mold, then air blown in to expand to mold walls.

Advantages of plastic packaging

Easy and versatile shaping; light weight; high impact resistance; bright colors; transparency; high function-to-cost ratio.

Disadvantages of plastic packaging

Possible transfer of flavors/odors to food; flavor scalping; many plastics not biodegradable; risk of contamination from recycled plastic; poor heat stability.

Crystalline melting temperature

When crystalline plastic becomes liquid, increasing free volume and permeability.

Polarity in packaging

Polar polymers pass polar molecules but resist nonpolar.

Lamination in packaging

Alternating polar/nonpolar layers to limit both water and oxygen migration.

Filling systems

Fill and seal; form, fill, and seal; thermoform, fill, and seal; blow mold, fill, and seal.

Types of package closures

Plugs, caps, cap liners, seals.

Electrolytic test

Checks seal integrity based on the idea that a correctly sealed package is an electrical insulator.

Dye test

Dye solution on one side; check other side for leaks.

Burst test

Tests strength and flexibility by applying internal pressure.

Aseptic packaging

Filling a commercially sterilized product into a sterilized container in an aseptic environment.

Required microbial reductions for nonsterile acidic products

Minimum 4-log reduction.

Required microbial reductions for neutral/low-acid products

6-log reduction.

Commercial sterilization targeting Clostridium botulinum

12-log reduction (12-D 'botulinum cook') for safety in low-acid foods.

Irradiation methods

UV, infrared, ionizing energy.

Modified Atmosphere Packaging (MAP)

The internal package atmosphere is changed to slow microbial growth and oxidation.

Active MAP

Air removed and replaced by a controlled gas mix ('gas flush').

Passive MAP

Desired atmosphere develops naturally via food respiration and microbial metabolism.

Common gases in MAP

Nitrogen (N2), carbon dioxide (CO2), Oxygen (O2), carbon monoxide (CO), argon (Ar).

Active packaging

Package components deliberately interact with product or headspace to improve quality/shelf life.

Oxygen scavengers

Often iron powder; bind oxygen to prevent oxidation and rancidity.

High Hydrostatic Pressure (HHP)

Food is exposed to 200-1000 MPa of pressure for a few minutes using a fluid like water.

Irradiation in food processing

Molecules absorb energy to form ions or free radicals that break chemical bonds and disrupt DNA and cell membranes.

Pulsed Electric Field (PEF)

High-voltage pulses are applied to food between electrodes, creating a lethal effect on microorganisms.

Ultrasound (US)

Creates regions of compression and rarefaction, leading to cavitation (bubbles form and collapse).

Thermosonication (TS)

US + Heat

Manothermosonication (MTS)

US + Heat + Pressure

Energy Savings

Faster processing times (microwave, RF)

Water Savings

Reduced need for traditional cool/heating water

Waste Reduction

Reduced gas and effluent emissions.

PDCAAS (Protein Digestibility Corrected Amino Acid Score)

The standard measurement for protein quality.

Complete Protein

Contains all 9 essential Amino Acids (EAAs) in adequate amounts.

Complementary Proteins

Combining different plant sources (e.g., legumes + grains) to achieve a complete amino acid profile.

Essential Amino Acids (EAAs)

There are 9 EAAs that must come from the diet: Histidine, Isoleucine, Leucine, Lysine, Methionine, Phenylalanine, Threonine, Tryptophan, Valine.

Soybeans (Glycine max)

Classified as an oilseed crop because it is high in both oil and protein.

Soy Protein Isolate (SPI)

90% protein. The most refined, soluble sugars and fiber are removed.

Soy Protein Concentrate (SPC)

~70% protein. Retains some fiber.

Soy Flour

~50% protein. Least refined.

Isoflavones

Phytoestrogens (genistein/daidzein) linked to heart health and reduced cancer risk.

Anti-nutritional Factors

Trypsin inhibitors interfere with protein digestion (inactivated by heat) and phytic acid binds minerals (zinc/calcium), reducing absorption.

Pea Protein

High in Lysine but low in Methionine.

Faba Bean

High protein content (25-30%), nitrogen-fixing (good for soil), but contains vicine/convicine (concerns for favism).

Chickpeas

High in fiber and folate; popular in 'clean label' products.

Wheat Gluten (Seitan)

Provides the 'chewy' texture in meat analogs due to its elastic properties.

Extrusion Cooking

Primary method for creating meat-like textures.

Hydration

Mixing protein with water.

Shearing/Heating

High temperature and mechanical energy denature the proteins.

Alignment

Proteins align into fibrous strands as they pass through a cooling die.

Animal Protein

Usually complete amino acid profile, high digestibility (90%), contains cholesterol, no fiber, high environmental footprint.

Plant Protein

Often incomplete amino acid profile (requires blending), moderate digestibility (70-90%), cholesterol-free, high fiber, low environmental footprint.

Legume Family

Fabaceae

Lysine

The most common 'limiting' amino acid in cereal grains.

Methionine

The most common 'limiting' amino acid in legumes.

TVP

Result of low-moisture extrusion; 'spongy' when hydrated.