olives olive production manual louise ferguson, g. steven sibbett, and george c. martin
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Olives
Olive Production Manual
Louise Ferguson, G. Steven Sibbett, and George C. Martin
Classification
• Family - Oleaceae
–Genera
• Fraxinus (ash)
• Ligustrum (privet)
• Syringa (lilac)
•Olea (olive)
Olea europaea
• Long lived evergreen trees
• Wood resists decay
• Top dies - stock sprouts
• Roots only 3 - 4 ft (1 m) deep
• Dense foliage, poor light penetration, cascading multiple branches, heavy fruit on terminals
Leaves
• Thick, leathery, oppositely arranged
• Each leaf grows for 2 yrs
–Spring abscission in 2 to 3 years
• Stomata on lower surface only
–nestled in peltate trichomes
Cultivars
• Ascolano 9 gm / 18.8% Blk Grn
• Manzanillo 5 gm / 20% Fr, Blk, Oil
• Sevillano 13.5 gm / 14.4% Blk, Grn, SpGm
• Barouni 7.4 gm / 16.5% Fr Blk
• Mission 4.1 gm / 21.8% Blk Gr Oil
Manzanillo
• Most widely planted
• Most popular for canning
• Low spreading 15 - 30 ft.
• Rooted Stem cuttings
• Not tolerant to cold
• Olive knot - Verticillium wilt
Sevillano
• Second most popular
• Spreading 25 - 35 ft tall
• Trained low for easy harvest
• Largest fruit in California
• Grafting 1 yr rooted cuttings
• Somewhat resistant to cold
• Bruises easily
Ascolana
• Rounded shape 20 - 30 ft tall
• Bruises easily
• Only 3 % of acreage in CA
• Canned ripe olives
• Fairly resistant to olive knot
Mission
• From Mexico in 1769, not Italy
• Tall upright, 40 - 50 ft
• Topped to facilitate harvest
• Small, low 6.5 : 1 fruit-to-pit ratio
• Rooted cuttings
• Trees survive 8oF
Mission Harvest
• Picked green - Spanish Green Processing because they are late and need to avoid frost.
• Red coloration - Ripe olive processin
• For oil because of high (21.8% oil)
• High monounsaturated fatty acid
Barouni
• From Tunisia in 1905
• Small tree 15 - 25 ft. spreading
• Large fruit, low fruit to pit ratio
• Resistant to cold
• For fresh use - process quality low
• Used for black-ripe table olives
Flowering
• Summer 2000 - Induction in veg buds
• Nov. 2000 - Floral induction
• Winter 2000 / 2001 - Chilling
• Spring 2001 - Flowers open
Chilling is Critical
• Optimum Flowering if chilling temps
–Maximum 60 to 65oF
–Minimum 35 to 40oF
• Poor flowering if
–Constant 55oF
• No flowering if
–No temp > 45oF or < 60oF
Influence of Leaves
• Very little dormancy
–Veg. Buds grow at or > 70oF
• Inflorescence formation
–Requires leaves on fruiting shoots
–Thus, prevent defoliation
•Hot winds can defoliate
Flower Buds
• Abnormally cold spring temps
–Detrimental to flower buds
• Floral differentiation 8 - 10 weeks before May bloom
– Irrigate to prevent stress
–Start season with moist profile
• Playing catch up will not do
Stress
• Causes predominance
–Of male flowers
–Why?
• Girdling can increase flowering
–Danger of Olive Knot
–Not a problem in Israel
–Root reduction
Pollination
• Monoecious
• Flowers borne axially along shoot in panicles
• Self and cross pollination occurs
Fruit Set
• 500,000 flowers per tree
• Need maximum of 10,000 fruit (2%)
–98% abscise in 14 days
–Goal is 3 tons per acre yield
• Sometimes insufficient perfect flowers to set full crop
• Need 10% set if inflorescence limited
Fruit Formation
• Embryo development
• Mature ovule (seed)
• Mature ovary (fruit)
• Requires rapid pollen growth
–Delays caused by cool temperature
• Parthenocarpic fruit (shotberries)
Sigmoidal Fruit Growth
• Endocarp (pit) enlarges to full size and hardens in 6 weeks
• Endosperm (liquid to solid)
• Embryo development
• Embryo maturity (September)
Maturation
• Gradual growth
–Mesocarp (flesh)
–Exocarp (skin and peel)
• Color change (harvest index)
–Green straw (optimal) Red (maybe) Black (unacceptable)
Harvesting
• Profit or loss depends on accuracy of harvest in October
• Delaying harvest = heavier fruit (more valuable)
• Delaying too long = black fruit & frost damage
• Oil content increases in January
Fruit Thinning to Avoid Alternate Bearing
• Hand thinning
–Both hands - heavy rubber gloves
–Strip fruit while leaving leaves
• Leave 6 fruit / foot of twig
• Complete 3 weeks after full bloom
• Effective but not cost effective
Thinning by Pruning
• Prune more heavily on “on” years
• Prune more lightly on “off” years
• However, not cost effective
Chemical Thinning
• NAA effective but must treat prior to knowledge of crop size
• Treat 12-18 days after full bloom (FB)
• Apply 10 ppm for each day after FB
–15 days after FB = 150 ppm
–Dilute spray (300 - 400 gal water per acre
Thinning Ornamental Olives
• Olives in landscape are more desirable if all the fruit are removed
• Use 200 ppm 2-3 days before FB
–Use second spray 1 week later
• Large trees require power sprayer
–10 - 15 gal per tree
• Detrimental if temperature > 100oF
Processing Olives
• Types
–Black-ripe (BR) - 99% in CA
–California-style green
–Spanish-style green (<1%)
• Pickling - process of adding lactic or acetic acid
Chemical Composition of Ripe Mission Olives (%)
• Water 55.0
• Brix 13.1
• Oil 21.4
• Sugars 4.6
• Protein 1.7
• Mannitol 4.4
Oleuropein
• A glucoside (bitter factor in fresh olives)
• Destroyed by dilute alkali at room temperature
• Remove alkali (1 - 2% lye) and bitterness does not return
Pigments
• Anthocyanins are major pigment
• Increases until fruit is ripe
• Decreases in overripened fruit
• Light increases formation
• 10 times more anthocyanin in fruit ripened in light vs dark
Salt Free Storage
• Acidulant solution
–0.67% lactic acid
–1.00% acetic acid
–0.30% sodium benzolate
–0.30% potassium sorbate
Traditional Brine System
• Concrete or wooden tanks
• Capacity - 20 tons
• 5.0 - 7.5% NaCl
–20 - 30o Salometer
–Saturated solution - 26.5% salt = 100o on Salometer
Storage Containers
• Open-top redwood tanks 5x6 ft
• Holds 2.5 tons of olives
• Polyethylene 6 mil plastic prevents contact between olives and inside of tank
• No fermentation in this system
• Flavor better than in brine
California Style Black Olives
• Paraffin or plastic lined 20 T tank
• Four overhead pipes
–Water
–Dilute dye
–Dilute brine
–Compressed air
Lye (NaOH) Treatment
• 3 - 5 applications of 0.5 - 1.5%
• Better color by
–Reducing lye concentration
– Increasing treatment numbers
–Reducing duration
Color Formation
• Lye helps
–Natural phenolic compounds to oxidize and polymerize
–Causing formation of black pigment
–Provided aeration is present
Calcium Helps Fix Color
• Color formation most rapid at 8.0 to 9.5 pH
• Retention better in hard water
• Ca(Cl)2 (0.1 - 0.5%) improves color retention
Lye Removal
• Lye removed by changing water in tanks at least twice daily
• Solution stirred frequently with paddles of compressed air
• Lye removed in 3 - 4 days
Canning
• 7.0 - 7.5 pH at time of canning retains color
• Packed in C-enamel lined cans
• Filled with 2 - 2.5 % salt brine
• Cans exhausted at 199 to 205oF for 5 min to reach 170oF or higher
Finish Canning
• Rebrined and sealed at 170oF in a double seamer
• Olives in glass containers processed in retort for 70 min. at 240oF
Spanish-Style Pickled Green Olives
• Fruit reaches full size but harvested before color changes
• Promptly placed in shallow paraffin - or plastic-coated concrete pickling vats
Lye Treatment
• Dilute lye (1.25 - 1.75%) at 54 - 70oF penetrates 3/4 way to pit in 8 - 12 hrs.
• Small amt of untreated bitter flesh characteristic of green olives
• 1 drop of phenolphthalein to cut surface shows depth of lye penetration
Post Lye Treatment
• Olives washed in cold H2O 24-36 hrs
• Water changed every 4 - 6 hrs
• Then response to indicator very faint
Fermentation
• Washed, lye-treated olives transferred to 50 gal oak barrels
• Head replaced and hoops driven
• 11% brine added through side bung
–Lactic acid content 0.8 - 1.2%
–3.8 pH or less
• Fermentation at 75 - 80oF for 1-12 mo
Producing Olive Oil
• Spain, Italy, and Greece (in that order) produce 80% of world’s oil
• They consume 75%
• USA < 1% of world’s olive oil
• International Olive Oil Agreement
• Administered by International Olive Oil Council in Madrid, Spain
Fatty Acid Profile
• Oil Saturated Unsaturated
• Mono Poly
• Olive 1st CP 3 88 9
• Olive 2nd CP 11 83 5
• Pecan C P 9 73 18
• Cardin Pecan 5 85 10
• Walnut EP 9 18 73
• CP = Cold Pressed, EP= Expeller Pr
Definition of Olive Oil
• Olive oil - obtained solely from olives
• Excludes oil extracted by solvents or reesterification processes, or any mixtures with other oils
• Pure olive oil cannot be any olive residue oils
Virgin Oil
• Mechanically pressed from olive fruit without using heat - cold pressing
• Only washed, decantation, and centrifugation (natural product)
• May have vintage years on label
Grades of Virgin Oil
• Virgin Olive Oil Extra
–Extra Vergine (Italian)
–Vierge Extra (French)
• Pure unadulterated oil from top quality olives
• Perfect taste and odor
• Max of 1% acid and strong odors
Other Olive Oils
• Virgin Olive Oil Fine or Fino
–Almost perfect taste but 1.5% acid
• Semi-fine or Ordinary Olive Oil
–Good taste maximum acidity 3.3%
• Virgin Olive Oil Lampante > 3.3%
–Not for human consumption
Poorer Grades
• Refined oils
–Caustic soda used to purify virgin oil from cull fruits
• Blended oil
–Blend of refined and virgin oil
–Most imported olive oil in USA
Residue Oil
• Olive-residue oil obtained by treating pomace with solvents
THE END