Metodi deamarizzazione Olive

Fermented Vegetable Products

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

Main Species in Fermented Vegetable Products

• Sauerkraut: Cabbage, salt; Leuconostoc mesenteroides, Lactobacillus brevis, Lactobacillus plantarum
• Cucumbers: Cucumbers, salt, vinegar; Pediococcus pentosaceus, L. plantarum
• Capers: Capers, water, salt; L. plantarum, Lactobacillus pentosus, Lactobacillus fermentum, L. brevis, Lactobacillus paraplantarum, Enterococcus faecium, P. pentosaceus
• Olives: Olives, salt, water; L. plantarum, Lactobacillus pentosus, yeasts

Examples of Worldwide Fermented Vegetables

• Sauerkraut: Cabbage, salt; Leuconostoc mesenteroides, Lactobacillus brevis, Lactobacillus plantarum (International)
• Cucumbers: Cucumbers, vinegar or salt; (International)
• Capers: Capers, water, salt; (Mediterranean)
• Kimchi: Napa cabbage, radishes, salt, spices; Leuconostoc mesenteroides, Leuconostoc pseudomesenteroides, L. plantarum, L. brevis, Lactobacillus curvatus, Lactobacillus sakei (Korea)
• Dhamuoi: Cabbage, other vegetables, salt (Philippines)

Characteristics of Table Olives

• Initial state: Bitter flavour due to oleuropein (a glucoside containing glucose, elenolic acid, tyrosol).
• Maturation: Olives remain bitter; deamarization necessary to make them suitable for consumption.

Transformation and Qualitative Indices of Table Olives

• Pulp percentage: Must be 80% or over; ratio of pulp to pit (P/N) should be at least 4.
• Consistency: Pulp should be firm, turgid, and not wrinkled.
• Pit: Fruit pit should detach easily from pulp.
• Colour: Colour depends on desired destination (Green, Rosé, Black)

Chemicals of Olive Bitterness

• Preservation: Prevents bitterness.
• Ester linking: Maintains oleuropein's bitter flavour.

Chemistry of Deamarisation

• Methods: Alkali or acid hydrolysis of oleuropein, chemical oxidation, enzymatic hydrolysis.

Chemical, Spaniard or Seville Method of Deamarization

• Process: Treated with sodium hydroxide solution.
• Wash: Multiple washes required to remove sodium hydroxide.
• Saline: Placed in 5-6% saline solution which migrates soluble fruit components allowing microbiological activity.

Biological or Natural Method of Deamarisation

• Process: Uses certain lactobacillus species.
• ẞ-glucosidase: Found in select lactobacillus species, acts on oleuropein.

Greek Method of Deamarization

• Process: Uses a 9-10% saline solution.
• Yeasts: Dominant in microbiological population during this method.

Defects and Alterations of Olives

• Incomplete fermentation: Low salt concentrations, poor hygiene
• Butyric fermentation: Bacteria; unpleasant odor
• Putrefactive fermentation: Bacteria; unpleasant odor.
• Gas formation: Gas bubbles; caused by microbes.
• Softening: Soft texture; caused by poor conditions, high temperatures.
• Stringiness: Stringy consistency; result of dextran polymer formation
• Darkening: Oxidation
• Pink Colour: Caused by certain yeasts.

Sauerkraut Production Process

• Preparation: Removing outer leaves, washing, thinly slicing.
• Salting: 2-2.5% salt by weight.
• Mixing: Mixing sliced cabbage with salt.
• Fermentation: 1-2 months at 18-22 degrees Celsius.
• Packaging: Packaging
• Heat Treatment: Optional.

Sauerkraut Fermentation Stages

• Stage 1: Heterofermentative (gaseous phase); Leuconostoc mesenteroides, Lactobacillus brevis
• Stage 2: Homofermentative; Lactobacillus plantarum