Producta Vegetabilium Fermentata

Fermentated Vegetable Products

• Professor: Maria Luisa Savo Sardaro
• University: Università San Raffaele, Roma
• Website: www.unisanraffaele.gov.it

Principal Fermented Vegetable Products and Microbes

• Sauerkraut: Cabbage, salt; Leuconostoc mesenteroides, Lactobacillus brevis, Lactobacillus plantarum
  • Primarily in Northern/Eastern Europe, United States & Asia (including kimchi)
• Cucumbers: Cucumbers, salt, vinegar; Pediococcus pentosaceus, L. plantarum
  • Primarily in Northern/Eastern Europe, United States & Asia
• Capers: Capers, brine, salt; L. plantarum, Lactobacillus pentosus, Lactobacillus fermentum, L. brevis, Lactobacillus paraplantarum, Enterococcus faecium, P. pentosaceus
  • Primarily in Mediterranean countries (Greece, Italy, Spain, Turkey, and Morocco)
• Olives: Olives, salt, brine; L. plantarum, Lactobacillus pentosus, yeasts
  • Primarily in Mediterranean countries (Greece, Italy, Spain, Turkey, and Morocco)

Examples of Worldwide Fermented Vegetable Products

• Sauerkraut: Cabbage, salt
• Cucumbers: Cucumbers, vinegar/salt
• Capers: Capers, salt/brine
• Kimchi: Napa cabbage, radishes, salt, various spices
• Dhamuoi: Cabbage, various vegetables

Characteristics of Table Olives

• Initial state: Bitter taste (oleuropein)
• Processing: Deamarization required; removes bitterness
• Treatments: Chemical (alkaline or acidic hydrolysis), enzymatic hydrolysis
• Color: Olive color depends on intended use (green, greenish-yellow, pink/rose, dark/black)

Quality Indices and Attributes of Table Olives

• Pulp percentage: 80% or more
• Pulp-pit ratio (P/N): 4 (80%) - 6 (86%) ratio is desirable
• Texture: Firm, not wrinkled or shriveled
• Pit removal: Easily separated from fruit

Bitterness of Olives

• Oleuropein: Glucoside responsible for bitterness
• Hydroxystirosol: Essential for bitter taste
• Chemical modification: Removing bitterness involves changing structure of hydroxystirosol

Chemical Deamarization

• Alkaline/acid hydrolysis: Involves reacting substance with strong base or acid
• Oxidative reactions: Reaction of hydroxystirosol with oxygen
• Enzymatic reactions: Enzyme-catalysed reactions
• Chemical method: Using sodium hydroxide

Biological Deamarization

• Enzymatic Hydrolysis: Using special enzymes that break down bitter compounds; some types of Lactobacillus
• Different methods (chemical, biological, Greek method): The chemical and biological methods are contrasted to the Greek method.

Fermented Vegetables: Methods to Deamarize

• Chemical (Spanish/Sevillian Method): Uses alkaline solutions for hydrolysis
• Biological (Natural/Biological): Uses enzymes to remove bitterness
• **Greek Method:**Uses a higher concentration of salt (9-10%) followed by microbial fermentation.

Microbial Interactions during Fermentation

• Initial stages: Enterobacteriaceae (gram-negative bacteria)
• Subsequent stages: Lactic acid bacteria (LAB) such as Pediococcus and Leuconostoc, followed by Lactobacillus plantarum or Lactobacillus pentosus (LAB)

Defects and Alterations in Fermented Vegetables

• Incomplete fermentation: Sugar is not fully consumed, improper conditions.
• Bacterial spoilage: Spoilage by various bacteria
• Butyric fermentation: Rancid butter smell
• Gas formation: Bubbles in solution, caused by some micro-organisms; pH alteration.
• Color changes: Browning, pinking or redness; caused by fungi or bacteria.