Vegetable Fermentation II

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Vegetable Fermentation (II)
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Key points for vegetable fermentation

• Benefits
• Enhanced preservation
• Desirable flavor and texture property
• Antimicrobial activity
• High conc. of thiocyanates and other
  sulfur-containing comp.
• Nutritional property
• Sauerkraut has anti-scurvy properties (high
  vitamin C)
• Koreans consume 43Kg per year (120 g/day) of
  kimchi

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Key points for vegetable fermentation

• Natural fermentation
• No heat process to inactive other flora
• Natural lactic acid bacteria to carry out
  fermentation
• LAB minor population, but dominant in successful
  product fermentation
• Succession the fermentation depends not on any
  single organism, but a consortium of bacteria
  representing several different genera and
  species. A given organism (or group of organisms)
  initiates growth and becomes established for a
  period of time. Due to accumulation of inhibitory
  compounds, growth slows down and gives way to
  other species that are less sensitive to those
  factors. (Fig. 7.3)
• Bacteriophage may also have a role

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Sauerkraut

• Leuconostoc mesenteroides
• Has relatively short lag phase and high growth
  rate at low temp (15-18?C)
• Heterofermentative pathway (lactic acid, acidic
  acid, CO2, ethanol)
• Acidic environment (0.6-0.8, as lactic acid)
  inhibit non-lactic competitor and favors other
  LAB
• Acid approaches 1.0, inhibit L. mensenteroides
  (4-6 days)
• Other homolactic bacteria
• Acidity 1.6, pH below 4.0, only L. plantarum can
  grow
• Final acidity 1.7, pH 3.4-3.6 (Fig 7-2)

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Kimchi

• Most popular of all fermented foods
• More than 100 varieties with various raw
  materials and processes
• 360 million Kg produced annually, 100 grams daily
  consumption, 12 of the total food intake
• Multiple ingredients, flavor and texture
  properties
• Nutrition
• Vitamin C, B, calcium, iron, potassium, dietary
  fiber, antioxidants, live microflora
• Functional food
• Producing antimicrobial compounds

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Pickle Production

• Any vegetable or fruit preserved by salt or acid
• Most important cucumber
• 1 billion Kg in the US used for pickles (half of
  the crop)
• Now more than half of the pickles are not
  fermented (direct add acetic acid)
• Types
• Fresh-packed (non-fermented)
• Refrigerated (non-fermented)
• Fermented (processed)
• Distinctive flavor and texture

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Manufacture of fermented pickles

• Rely on salt, oxygen exclusion, anaerobiosis to
  select for growth of
• instead of dry salt
• Salt conc. higher than that for sauerkraut
• Less diverse microflora
• Brine at least 5 salt, some 7-8, up to 12
• Up to 2 months, end pH 3.5, acidity 0.6-1.2
  (as lactic)
• L. mensenteroides cannot grow
• Initiated by L. plantarum and Pediococcus sp.
• Brine condition inhibitory to coliforms and other
  non-LAB
• De-salted after fermentation for further
  consumption
• Can use starters (controlled fermentation) (Fig
  7-5)

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Defects

• Pickles
• Bloaters and floaters (Table 7-4)
• Excessive gas pressure, internal cavity formation
• LAB (heterolactic, malolactic fermentation),
  coliforms, yeasts
• Control remove dissolved CO2 by flushing or
  purging with nitrogen gas
• Some can still be used
• Destruction and softening
• Slippery, loses crispness and crunch
• Cannot be used
• Pectinolytic enzymes by microorganisms
• Fungi
• Penicillium, fusarium, Alternaria, Aschyta,
  Cladosporium
• Control acidity

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Olives

• 90 of the world production used to make olive
  oil
• Only 7-10 consumes as table olives
• From middle East
• Italy, Spain, Greece, Turkey 75 of worldwide
  production, US less than 1, but 90-95 from
  California used to make table olives
• More than 70 on the US market are brined and
  canned (California-style olives)

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Composition

• Phenol and polyphenol compounds common to olives
• Color, antimicrobial activity
• Antioxidant
• oleuropein
• Bitter flavor
• Glucosidic phenols and oleropein

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Fermented olives

• Spanish-style (green Spanish-style)
• Treated with sodium hydroxide (lye) and fermented
  (natural microflora)
• Greek-style (natually black, ripe-style)
• Not treated with lye, but fermented (natural
  microflora)
• Ripe black- or green-style
• Lye-treated, not fermented
• Going through a special aeration treatment,
  promote oxidation of pigments and conversion of
  green to black (California-style)