Drying - Virgilio Siti Xoom

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History of Food
Preservation
(Storia delle tecnologie di conservazione
degli alimenti)
Marco Riva
DiSTAM – Università di Milano
[email protected]
Rif.: Food Preservation in History, in G. Borgstrom, Principles
of Food Science (2 vol., 1968); N. W. Desrosier
2
M.Riva /DiSTAM - UNIMI
Development of man, agriculture
and food techniques
The pre-agricultural times
correspond to collecting, hunting and fishing. It started approximately 3 million years BP.
The agricultural times
began with the development of agriculture simultaneously at six points in the world. It
lasted from 10000 years BP up to the 19th century.
The agro-industrial times
began with the industrial revolution. It lasted from the 19th century up to nowadays.
M.Riva /DiSTAM - UNIMI
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Pre-agricultural times
Pre-agricultural times is based on collecting, hunting and fishing.
This period corresponds to wild food. It started approximately 3
million years BP and lasted from the first human beings in the
Neolithic era up to the beginning of agriculture.
The search for food played a major role in the bio-cultural evolution
of man.
• Man invented, adapted and built up food complexes
• he domesticated fire
• he invented fireproof earthen pots to cook food
• he preserved foods by drying, smoking, fermenting and chilling
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Man as predator and cook
Man as a predator:
hunted, gathered food plants, fished, and made tools and instruments
adapted to these activities. They prospected for food plant species and set up the first food complexes. Hunting
big game contributed to shaping mankind's social organisation; cooking brought together people around the fire
and thus food consumption became a community feature.
The emergence of cooked food: food products can be eaten in three forms:
raw, cooked, or fermented (e.g., sauer kraut). While raw food is natural, the cooked food is referred to
as cultural. A very important step forward was made when man "was no longer satisfied with roasted
or grilled food, cooked in the dry heat of flames, so he invented the cuisine prepared with moist heat.
This moist cooking allows more diversity of dishes and flavors as well as a greater possibility of mixing
foods in the same meal.“Cuisine is much older than agriculture: men cooked their wild foods before
cooking agricultural food products. In Neolithic times the culinary revolution preceded the agricultural
revolution.
The revolution of containers: Man as a hunter/gatherer needed
containers to collect, transport, preserve, cook and eat... The first containers used to be
sea-shells, tortoise shells, tree bark...
The earthen pot (made of baked clay), a waterproof container which can be put on a
fire-place (hearth) was a major invention. Pottery artefacts are of great scientific value
because they can identify and characterize archeological cultures.
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Agricultural times
The agricultural period is based on the domestication of food plants and animals
which progressively constituted the main source of human food.
This period corresponds to the agricultural food products, transformed and prepared
inside of domestic consuming units.
During this period man gradually…:
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Invented agriculture,
selected founder species,
created villages and towns,
invented and improved acquisition and production tools,
transferred food species on a worldwide scale.
The 16th and 18th century were the times for major changes in Europe... when New
World species and foods came in Europe …. and when a new industrial and liberal
society set up on a traditionnal agrarian basis, and where is formed and developed the
agro-industrial period related to food.
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Beginning and development of agriculture
Agriculture and animal raising required the domestication of both animals and plants,
raising of species useful for human beings, and taking care of the factors that kept them
alive and productive.
Agriculture started simultaneously in several parts of the world. Euro-mediterranean
agriculture started in the Middle-East and spread, first to the western Mediterranean
region, then up to the northern part of Europe. This happened between 6000 and 2000
BP.
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Meso-America : maïze, bean, avocado, tomato, vanilla, cocoa
South America : tobacco, groundnut, potato, cotton, tomato, pine-aple, pimienta, Cassava, rubber-tree
Middle East : oat, wheat, peas, lentil, flax, olive-tree, vine, fig-tree, date palm-tree
Central Africa : mil, sorghum, yam, coffee, oil palm-tree
Western China : mil, soya, tea
South-East Asia, Southern Pacific : rice, banana, sugar cane, orange tree, egg plant, coconut tree, pepper
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Processing, Storing and Preserving
Agriculture offers a wide class of
foods
They can be stored, preserved to reach
market and consumers, and processed
to obtain new products, with optimal
nutritional or functional properties, or
to separate its constituents.
New and ancient food technology
moves from the goal to assure a
variety and a quantity of safe and
convenient foods to all
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The Food Timeline
http://www.foodtimeline.org/
3000 – 0 B.C
0- 12th
Century
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Vivaria
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Catch wild animal and keep them in
enclusures (Egyptian fowl house,
Romans artificial ponds)
Live fish marketing, poultry delivered in
bunches to market
Sperlonga, Villa di Tiberio
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Fresh food directly to market
or consumer
No cold chain
Fes (Morocco), market
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Smoking
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Beneficial preserving effect of smoke
was discovered by early cavermen
Fish: Salmon (North American Indians
and Eskimos), Swordfish (Iraqi)
Meat: Arawaks - meat cured in the sun
and then smoked over a fire of green
wood, over a grid (boucan >
bouccaneer)
Smoke contains formaldehyde
and other preservatives
Smoking promotes local drying
and surface sanitisation
Fish smoking
Boucanning
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Drying
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From experience of effect of dry air in
desert or mountain, with eventual
supplement of fire
Seeds near cavermen
Dates, figs and grapes in Middle West
Asparagus, cabbage, cherries and plums
by Romans
Apricots trodden in pulp, boiled and
dried on trays > arabic world
Dehydration reduce microbial
growth and enzymatic changes
Dried foods are less voluminous
and practical for long storage
Guatemala - The clean beans, still in
their parchment, are now ready to dry
Drying the
apricot pulp
in a portable
solar drier
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Drying
The dry raisins and figs were a popular
energizer for Roman soldiers
A lye methods (olive oil + ash) of grapes
was employed to speed drying near
Greeces, Romans and Iroquois Indians
Sun or Wind dried meat was an early
man’s ratio (Xarqui of Brasilian Indians,
Biltong in South Africa, Akutok from
caribou near Eskimos, Charqui from
llama near Incas >> bresaola!)
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Drying was an alternative of
salting when salt was scarce
Drying of the Zibibbo grapes
The word BILTONG is derived from
the words "BIL" (BUTTOCK) or
meat and 'TONG" or strip. So it is
just a strip of meat.
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Drying
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Pemmicam from buffalo meat near
Indians of North America, by
pounding dry meats (difficult to chew)
in fragments, stored in skin bags filled
with grease for travel
Dried milk curd from Tibet, dry
koumiss and urum from Tartars (the
milk skin produced by boiling is poured
off, cooled and dried. If placed in a
wooden barrel or leather bag, it keeps
well all winter)
Dried foods can be powdered and
eated after water addition
Making
Pemmican by
pounding jerky
into powder. The
meat is then
mixed with grease
(deer tallow is
perfect) and rolled
into balls or
stuffed into
containers.
Mongolian women make urum, or socalled white butter, from milk
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Drying
M.Riva /DiSTAM - UNIMI
Drying in the open air is the most
ancient method for preserving fish
This technology was typical of
Phoenicians, but also near the costal
populations of Norway and Eastern
Sweden
Indians and Eskimos dried salmon, cod
and smelt after evishering and splitting
along the blackbone, with elaborated
incisions
Natural drying is slow and can be
speeded by different practices
Fish drying near Eskimos
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Drying
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Cereal seeds were always dried for storage
In the Middle East bulghur, obtained by
boiling wheat, spread it in the sun to dry,
and then polished by hand from bran, is
nowadays employed as basis for soups.
The technique is similar to rice parboiling,
employed in East Asia.
Pasta natural drying is documented only
in 10th Century (North Africa and Sicily)
In East Asia, tea leaves, after
fermentation, were sun-dried to prepare
the stable ingredient for beverage.
Drying can be speeded with hot
and dry air circulation
M.Riva /DiSTAM - UNIMI
Bulghur
Tea leaves drying – The first description
of the procedure was recorded by Lo-Yu
in 780 B.C.
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Salting
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The practice of salting fish is dated 3500
BC in Mesopotamia, Egypt and Indus Valley
Phoenician fishermen employed salting to
preserve fish captured in the Near Atlantic
The art of curing meat is also very old. Salt
grain (“corn”) >> corned beef
Salt was a strategic resource in Roman
Empire, employed to preserve also
vegetables, butter and cheese
Salami and bacon production were old
specialties: later, in bacon, saltpeter
substituted marine salt >>> pink colour
Salt reduces water activity,
inhibits microbial growht and
enzymatic activity
Salting Vats that are used for
preserving fish caught
Salt in Sahara desert
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Concentration
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In ancient words sugar was unknown: honey
or concentrated fruit juice are employed as
sweeteners
The Indians of Northeast discovered the
manufacture of maple sap, by evaporation
from wooden or bark vessels or by putting
hot stones into the liquid
In the Middle East and Roman empire the
juice pressed from grapes was boiled to
obtain a syrup called dibs or sapa
Sugar from cane has been diffused in
Europe as a consequence of Arabic
invasions
Water content reduction and
sugar increase stabilize juices
and syrups
Gathering sap from sugar trees for
making maple syrup
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Fermentation
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The oldest recipe for barley wine (beer)
is in a cuneiform inscription on a
Babylonian library
The practice of tapping the date palm
to produce date wine is today
widespread in North Africa
Grape wine production came from
Mesopotamia and is an industrial
activity near the Romans
Honey was the basis for the making of
the miod of the Vikings and the mid of
Siberian peoples
Fermented apple syrup (cider) was
known earlier than its production
became usual in Normandy
monasteries
Barley fermentation in ancient Egypt
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Fermentation
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Leavening of water-flour mixtures in
Egyptian era was a revolution in bread
making, allowing, after cooking, to obtain a
soft and aromatic product
Not only wheat, but also rice was
fermented, not into a beverage, but to
provide a main item near Andean populace
(“sierra rice”)
In East Asia, rice was fermented into
alcoholic beverage, in the form of sake
Other cereals (sorghum, maize) or roots
(cassava, potato) were subjected to
fermentation in different civilization, to
preserve and transform amilaceous foods.
Alcohol is a preservative, not only
an euphorizer
Breadmaking in Ancient Egypt
Kuchikami-no-saké was made by chewing the
rice or other grain, spitting it out into a
container and allowing the enzymes in the
saliva to ferment the grain for several days.
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Fermentation
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The utilization of molds and other
microbes to make soybean accessible to
man’s digestion was known in early China
Mucor cultures were employed to produce
the similar-cheeses sofu and tofu in China
and Japan, and tempeh (from copra) in
Indonesia
Most of these old manufacture practices
are scientifically based: temperature was
regulate, short-range heating was applied to
remove undesirable intruders.
Fermentation allows the
manufacture of new, stable and
very ingenierized foods
Tofu production
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Fermentation
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Sauerkraut is one of the oldest forms of
preserved food. Roman are credited to learn
the technology from Germans, where
cabbages were preserved for the winter
trough lactic acid fermentation.
Sauerkraut (due to his high content in
ascorbic acid) is credited with having kept
scurvy away from ships during XVIIth Cent.
Romans employed the same technique to
preserve other vegetables.
The Slavs still have their koumiss and other
drinks based on lactic fermentation.
Lactic fermentation has not only
a preservative effects but is also
probiotic
Sauerkraut production
Selling of
fermented mare’s
milk in Almaty,
Kazakhstan
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Fermentation
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Fermented meat products (sausages and
salami) were a popular dishes near
Romans, and are nowaday a tradition in
all Mediterranean countries
Duk’s eggs were fermented and
preserved by the early Chineses by an
Pidan is an
alkaline treatment to make “pidan”. The
appearance of pidan differs from fresh alkali-fermented
egg, with long
eggs in that the white becomes a
shelf life
semitransparent tea-brown color, and
the yolk is solid or semisolid with a
dark-green color
In southeastern Asia the proteolitic
fermentation of fish and shellfish is still
practiced (nuoc-mam of Vietnam and
nam-pla of Bourma) to make a clear fish
sauce.
Pig’s
breading
and salami
production
in Ancient
Roma
Nuoc-mam is
prepared by
fermentation and
salting of fish in form
of clear hydrolyzate
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Highly Fermented products
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Buried heads of salmon (early Eskimos),
fermented herring (Sweden), rankorret
(fermented trouts, Norvegia): salted and
fermented fish are considered a delicacies
Vinegar from sour wine was largely
employed to preserve vegetables and meats
near Romans
Garum production (salted, fermented and
aromatized anchoy, preserved with vinegar in
sealed anphora) was a delicacy of Roman
cuisine and a very technological activity in
Roman colonies
“Carpione” or “escabeche” preserving
techniques remain typical in Mediterranean
countries, and are based on vinegar addition
to fried fish.
Garum or liquamen: fish, fish
intestines and salt are mixed together
and allowed to ferment in sealed
containers
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Freezing
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The ancient peoples living in iced regions
were well acquainted with the art of freezing:
plant tubers and animal meat among
Eskimos, sour milk among Yakuts
North Americans Indians living in cold
regions preserve and delivery poultry, game
and fish in a frozen status
In the 17°th Cent., frozen dishes were served
at the Csarist courts
Marketing of frozen fish, preserved with ice
was diffused in the 18°th Cent., before
artificial freezing methods introduction
Freezing stops the microbial
growth and the enzymatic
activities
Freezed Similaun’s man
The most famous of all
mammoths, the frozen
Berezovka mammoth.
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Freeze-drying
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The peoples of Peru and Bolivia were able to
transform their cherished potato into a
“chuno” by freezing it at night and allowing
it to thaw in the daytime, as a consequence
of the great differences in ambient
temperatures
Reindeer meat winter-dried by the Lapps and
Tibetan methods to preserve meat are other
applications of freeze-drying
Alaska pollok (mintai) and some practices of
preserve stockfish in Norway are other
examples of this technique
Freezing promotes ice crystal
formation and high-rate heating
allows to sublimation of ice
The “chuno” (shredded and
freeze-dried potato) was a
strategic resource in Andean
populance.
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Fat-embedding
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Pemmicam of North American Indians is
the most representative example of the
preserving activity of fat covering
In the Amazon regions, fish and meat were
roasted in its own fat, sliced and sealed in
jars covered with fat to make “mixiria”
In Mediterranean countries blanched
vegetables and bleu fish were preserved in
olive oil
Ducth plants were used to put up covered
salmon with melted butter in tin and sealed
cans prior to Appert’s invention.
Fat-embedding promotes air
exclusion, reduces oxydation and
diminishes microbial growth
Ch'itsuh (Pemmican) from
Eskimos
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Chemical preservation
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The use of mustard seeds both as a
condiment and a preservative has been
established in Egypt (1500 B.C.), was known
by the Romans as a tool for must storage and
was carried in Britannia, originating the
classical mustard sauces.
Sulfur was used by ancient peoples for
fumigation purposes and as preservative for
wines
A lot of aromatics (i.e., pepper) have an antibacteria effect and were largely used to
assure sanification of dishes. Aromatic
woods or therpenic essences have similar
effects
The use ok chemical preservative
has a long history before the
modern chemistry revolution
Mustard seeds
and classical
italian
“Mostarda”
Retzina is a greek wine
aromatised and
preserved with pine
resins
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Chilling
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Cooling thought evaporation was the basis for
the porous earthenware jars still in use in the
Mediterranean regions
The filling of ice and snow stores was a ritual
ceremony in ancient China and was employed
by Romans and Japanese
For centuries in Russia, North America and
Northeastern Europe ice was harvested in
winter from the lakes and saved for the warm
summer
Lowering of the water temperature by
dissolving salt was proposed as the first
refrigeration technology and used for chilling
wines and for Sorbetto production in Florence
about 1550 AC
Refrigeration slows the decay of
food quality and microbial growth
Himuro (ice room, Japan)
Ice cream production device
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Dairying
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Through the cuneiform writings of the
Sumerian (6000 B.C.) and from drawing and
carvings, it is apparent that dairying was highly
developed by the ancient peoples
Curd is the surprising result of storage of milk
in animal goatskin
The further discovery was the direct use of
rennet, also from calves, and the effect of
salting and drying on curd separated from the
whey
Both the ancient Carthaginians and Ethiopians,
before the Greeks and Romans, made hard
cheese
The earliest reports of the extensive use of
butter and of its ripening and storage in cask
originated from the 5th Cent. with the Celts in
Ireland
Cheese in ancient Egypt
Cheese and butter seller in a
painting of XIVth Cent.
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Meat-handling
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Sausage is one of the old forms of processed
foods, preserved through drying, salting,
smoking, fermentation, spicing and sometimes
also cooking
Sumerians and Chinese are able to ground their
partially dried meats and make sausage by
adding spices
Even before historical records, the Greeks
prepared a sausage somewhat resembling the
present-day frankfurters
The word “sausage” is derived from the Latin
“salsus”, meaning salted, or, literary, preserved
meats
Sausages exposition
Traditional sausage
production
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Fish
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Preservation of fish includes not only
smoking, drying, fermentation and salting,
but also picking in salt solutions and limecuring
The origin of pickling is uncertain, but
Romans carried it a high degree of
perfection, especially in preserving swordfish
from Sicily, tuna from Bysantium and Cadiz,
makerel from Spain, and mullet from Exone.
Brine-salting received is greater development
during the 13th Cent with herring
Curing of fish with lime to facilitate water
uptake and swelling of the tissue was
practiced in the Middle Ages in Scandinavia:
this technique is on the basis of the
preparation of stockfish
White fleshed fillets are being
rolled into rollmops ready for
poaching then pickling
Production
of stockfish
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M.Riva /DiSTAM - UNIMI
The agro-industrial period
The agro-industrial period is characterized by a combination of agricultural and
industrial activities and by services.
It is a time for agro-industrial food products, transformed and prepared from
agricultural products by the agro-food industry.
The industrial revolution changed the working conditions used to obtain agro-food
products by many ways :
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stimulating the scientific research,
increasing education rate among farmers,
inventing adapted tools according to an increasing production,
revolution in transportation which allowed to develope a worldwide economy,
transforming agricultural products into agro-industrial food-products,
contribution to the accession of a society of mass consumption.
Industrialized societies reached the stage of mass consumption though even the
richest societies could not eradicate starvation.
In underdeveloped poor countries starvation and malnutrition remain. The old
struggle of man against food shortage is an ongoing struggle.
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Industrial era: the background
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For many centuries no major invention took
place in the field of food preservation
The discovery of the New World is
accompanied by new products circulation
(maize, tomato, potato, cocoa) without
technique advancement
Except for the discovery around 1330 that
gutting greatly improved the quality of salted
herring, one has to wait until the turn of the
19th Cent. to find real innovation in food
preservation
The discovery from Appert of the heat
processing combined with hermetic sealing is
reputed the crucial data for food technologies
progress, but is true that is the energy
revolution that represent the most significant
fact: heat and cold can be artificially produced
and applied with a fine control
Solanum tuberosus (potato): a
food from the new world
Salted and smoked herrings were an
important resource in Middle Ages
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Live product delivery
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Well-smacks for the preservation of live fish
were introduced in England in 1872
At the end of the 19th Cent. enclosures and
pens were common for retaining whitefish and
sturgeon during the fall for sale in the early
winter
At the present time a lot of delicate fish and
crustaceans (including lobsters) are always
marketed alive
Fish transported alive in the farm in
canvas containers after capture
Lobster marketing
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Natural ice and chilling
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F.Tudor was the first man to organize ice trade
(1805) on large scale
During the first half of the 19th Cent. iced fish
consumption were common in the major town
of Europe and USA, not only in the fishing
ports
J.Perkins made the first refrigerating machine
(UK, 1834)
A more practical compressor was constructed in
1874-76 and based on the use of sulfur dioxide
or ammonia
In the 1870-80 period experimental shipment
thought Atlantic of chilled meat under
mechanical refrigeration was made
A car employed to delivery
chilled fish
Old type of home
refrigerator
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Freezing
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F.Bacon is credited with the invention of
artificial freezing (1626), but it describe only the
effects of lower temperature on an icedchicken!
Open-air freezing of herrings was an industrial
activity on the Newfoundland and the New
Brunswick during the 19th Cent.
Before the refrigeration compressor,
commercial food freezing started sporadically in
USA, UK and Russia with the employing of icesalt mixtures
Piper patent (1861) is the first practical device
for freezing fish, based on ice-salt mixtures
employed to chill an insulated cold-storage
room. In another invention the product is
enclosed in thin sheet-metal pans, removed at
the end of the circulation of ice-salt mix
Cold storage room for fish
preservation
The Refrigerated Railroad
Car
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Further developments in freezing
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Frozen foods hat to wait until the advent
of the compressor (1876) to become a
commercially feasible project
First freezing plants were erected to
Sidney (meat) and Astrakan (Russia)
The first transoceanic shipment of
frozen meat took place in 1877 from
Buenos Aires to Le Havre (“cargo “Le
Frigorifique”): meats remain acceptable
at -17°C for 6 months
« Le Frigorifique » (the
refrigerator), 1876
The housewife of Northwest were credited for the beginning of fruits
freezing, keeping ice provided by his husband in a local ice store to prepare
barrels and cans of frozen berries
In 1904 S.H.Fulton initiated his investigations on the freezing of sugared
strawberries and raspberries
The plate freezer of C.Birdseye (1929) is the next stage: vegetables and
fruits are quick-frozen with retail packaging
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Ice Cream
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The Florentine P.Coltelli is the first on
record (1660) to have manufactured
“sorbetto” and ice cream with the aid
of a salt-ice mixture
Manufacturing outside of the summer
season was started in 1750 by the
Frenchman Dubuisson
During the 19th Cent. a small vacuum
freezing machine, descript by E.Carrè,
was introduced into the Paris cafès
Commercial development of ice cream
production started in USA with salt-ice
plants first, and with mechanical
refrigeration later
The “mastella”, an ancient ice-cream device
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Freeze Concentration
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At the end of 18th Cent. a Swedish
apothecary, J.C.Georges, and an Italian
scientist, Mirabelli, recorded
experiments to concentrate fruit juices
(lemon always) by freezing
A process of concentrating grape juice
(must) was patented by E.Monti in
1906 and was based on repeated
freeze-thawing stages
In 1911 was patented a treatment of
spraying apple juice onto a slowly
rotating drum
The next developments were the
concentration by evaporation in high
vacuum and, in 1935, the realization of
a freeze-drying process
A modern freeze concentration
plant
The Shuttle mission food system
includes freeze-dried products
M.Riva /DiSTAM - UNIMI
40
Fermentation
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Attribution of fermentation to the effect
of microorganism was demonstrate by
Kutzin (1837, acetic acid), Mitsherlich
(1841, yeast fermentation) and Pasteur
later. The first method to prepare
fermenting yeast solutions is attributed to
Buchner (1897)
Manufactured baker’s yeast succeeded in
supplanting brewers yeast, or brau
The use of lactic cultures in cheesemaking
started in 1897, and in the same period
cultured yeast were introduced in
breweries and wineries
The employ of fermentation to produce
ethyl alcohol or lactic acid for industrial
purpose started in 1881
For centuries, breadmaking
employed mother’s pieces
A modern brewery with the
fermentation tanks
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Canning
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In 1809, the French chef N.Appert received
an official citation for a new method of food
preservation: his technique involved heating
of food in hermetically sealed glass bottles
and jars
The application of Appert was based on
observations by L.Spallanzani that by heating
peas for a sufficient length of time in sealed
test tube no spoilage occurred
The explication of the fundaments of these
applications is due to L.Pasteur ( 1873, food
spoiled trough the process of fermentation
because of action of microorganisms) and to
the subsequent studies of applied
bacteriology (1895-97, Russel and Prescott)
Appert’s invention is subsequent to other
application of heating preservation: bottling
of fruit (berries) using corks, preserving
cooked meat in a block-tin box of canister
with a hot fat covering
L'ART DE CONSERVER,
PENDANT PLUSIEURS ANNÉES,
TOUTES LES SUBSTANCES
ANIMALES ET VÉGÉTALES ;
OUVRAGE soumis au Bureau consultatif des Arts et
Manufactures, revêtu de son approbation, et publié
sur l'invitation de S. Exc. le Ministre de l'Intérieur.
PAR APPERT,
Propriétaire à Massy, département de Seine et Oise,
ancien confiseur et distillateur, Élève de la bouche de
la Maison ducale de Christian IV.
Reconstruction of an
Appert’s recipe
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42
The can and the autoclave
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Appert’s method was adapted in
England (1811) to tin-plate canister
(cans) by Durand and De Heine
Appert’s cooking method (hot water)
was substituted by superheated CaCl2
solutions (Solomon, 1861) and by
close kettle with either water and
steam (1874, Shriver)
Autoclaves were introduced in 1878,
on the basis of Papin’s (1679-1681)
prototype
Commercial applications started in
1840-1870, with canned tomatoes,
meat, milk, peas and asparagus, fruits
and jellies in glass and sardines in oil
Canning industry development was
supported by necessity of the Artic
explorations and of the Wars (USA
Civil war and sino-japanise war)
An ancient can
Denys Papin’s
“digester or engine
for softening bones”
M.Riva /DiSTAM - UNIMI
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Pasteurization
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Between 1860 and 1864 L.Pasteur discovered
that, by carefully controlled heat treatment,
most of the harmful microorganisms in wine
could by destroyed without deactivate the
useful ones
Soxhlet, a German chemist, may have the first
to pasteurize milk: this practice was common
in 1890 near Danish buttermakers and, later, in
USA
The pasteurization process employed
autoclaves first and retort tower recently.
Ultra-high temperature pasteurization (with
tube or plate heat exchanger or UHT process)
was introduced in 1948
During the last century pasteurization was
applied to wine, beer, fruit juices and other
beverages
An ancient device for milk
pasteurization
A modern milk
pasteurization plant
M.Riva /DiSTAM - UNIMI
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Drying
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Use of kilns feeded with hot air to dry
cereals and fruits was traditionally
practiced in cold and wet regions
The application of an hot water fast
immersion of product before drying was
applied at the end of 18° Cent.
The use of a stove to heat air in drying
chambers was common at the beginning
of 19° Cent.
A method to artificially dry cut vegetable
at low temperature and subsequent
compression was developed by Masson
and Chaollet
Artificial drying in tunnel or kiln was
commercially applied after 1850 to
prunes, potato and apples
Further developments regard spray,
vacuum and drum drying
James Jones chicory- drying kilns in
New Zealand
A tunnel drier
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Concentrating
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In 1862 G.Borden pioneered condensed
milk by presenting his patent for
concentrating cider, fruit juices and milk
The process consisted in evaporating
water of milk in vacuum pans,
resembling those employed in sugar
production, and in sealing the condensed
milk in under vacuum and hermetic tin
cans
The key of the treatment was employed
by the Anglo-Swiss Co (later the Nestlé)
and determined the commercial use of
concentration for products with high
convenience and good nutritional
properties
One of the most representative product
is today the tomato paste concentrate
The label of first condensed milk
A jacketed vacuum evaporator for
tomatoes
M.Riva /DiSTAM - UNIMI
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Filtration
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Removal of microorganisms through
filtration was introduced by Soviet
engineers in the 1920s
Microfiltration, ultrafiltration and Reverse
Osmosis for preserving purpose were
applied after the II World War to
This ancient Egyptian clarifying device was found pictured
beverages
on the wall of the tomb of Amenophis II at Thebes
Modified Atmosphere Storage
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Controlled Atmosphere Storage (CAS) was
used already in the 30’s, when ships
transporting fruits had high levels of CO2 in
their holding rooms, thus increasing the shelflife of the product. In the 70’s MA packages
reached the stores when bacon and fish were
sold in retail packs in the UK.
MAP of meat steak
M.Riva /DiSTAM - UNIMI
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Radiation
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In the last century ultraviolet lamps were
proposed and used to sterilize workspaces and
tools and to disinfecting drinking water
Research on food irradiation dates back to the
turn of the century. The first U.S. and British
patents were issued for use of ionizing radiation
to kill bacteria in foods in 1905. Food irradiation
gained significant momentum in 1947 when
researchers found that meat and other foods
could be sterilized by high energy and the
process was seen to have potential to preserve
food for military troops in the field.
By late 1946, the Raytheon Company had filed a
patent proposing that microwaves be used to
cook food. Later, food industry apply microwave
to sterilize foods
America's astronauts have been
eating irradiated foods from the
beginning of the space program
An old model of microvawe oven
M.Riva /DiSTAM - UNIMI
48
Last developments
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Electron beam processing. This technique involves the passage of an accelerated electron
beam through the product to be treated. Accelerated electron beams, like X-rays and gamma rays,
are ionizing radiations, which kill the bacteria coming in contact with them.
Ultra-high pressure. This processing technique has existed since the late 1890s. Basically, the
food product is placed in a flexible vessel (a pouch or container), and placed in a chamber under
ultra-high pressure (80,000 to 100,000 psi) and held for a few minutes. When you apply the
pressure, you're compressing the bacterial membrane, which, in a sense, stops respiration.
Pulsed Electric Field. In this technique, the product is pumped through a treatment chamber
in which electrodes are installed. The bacteria are exposed to high voltage as they pass between
these electrodes; this, in turn, causes "electro-poration" -- that is, a hole in the bacterial cell wall.
Induction, or ohmic, heating involves passing current through the material being pumped.
Because there is no hot surface, such as is found in a heat exchanger, sterilization can be achieved
without burn-on or other problems.
Vacuum packaging simply involves the removal of oxygen from the package before it is sealed.
Pulsed light is a method of food preservation that involves the use of intense and short
duration pulses of broad-spectrum "white light". For instance, the process was reported to be
effective to inactivate molds in a variety of baked goods and to extend their shelf-lives.
Active packaging may be defined as packaging that changes the condition of the packaged food
to extend shelf-life or to improve safety or sensory properties, while maintaining the quality of
the food. It includes antimicrobial film, oxygen scavengers, moisture controllers and a more
active role for ethylene absorbers to help reduce the pathogens and gasses that contribute to food
spoilage.
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