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 3 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 M.Riva /DiSTAM - UNIMI 4 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. M.Riva /DiSTAM - UNIMI 5 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…: • • • • • 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. M.Riva /DiSTAM - UNIMI 6 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. • • • • • • 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 M.Riva /DiSTAM - UNIMI 7 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 M.Riva /DiSTAM - UNIMI 8 The Food Timeline http://www.foodtimeline.org/ 3000 – 0 B.C 0- 12th Century M.Riva /DiSTAM - UNIMI 9 Vivaria 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 • • Fresh food directly to market or consumer No cold chain Fes (Morocco), market M.Riva /DiSTAM - UNIMI 10 Smoking • • 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 M.Riva /DiSTAM - UNIMI 11 Drying • • 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 M.Riva /DiSTAM - UNIMI 12 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!) • 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. M.Riva /DiSTAM - UNIMI 13 Drying • 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 14 • 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 15 Drying • 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. M.Riva /DiSTAM - UNIMI 16 Salting • 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 M.Riva /DiSTAM - UNIMI 17 Concentration • 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 M.Riva /DiSTAM - UNIMI 18 Fermentation 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 M.Riva /DiSTAM - UNIMI 19 Fermentation • 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. M.Riva /DiSTAM - UNIMI 20 Fermentation • 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 M.Riva /DiSTAM - UNIMI 21 Fermentation • 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 M.Riva /DiSTAM - UNIMI 22 Fermentation 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 M.Riva /DiSTAM - UNIMI 23 Highly Fermented products 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 M.Riva /DiSTAM - UNIMI 24 Freezing • 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. M.Riva /DiSTAM - UNIMI 25 Freeze-drying • 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. M.Riva /DiSTAM - UNIMI 26 Fat-embedding • 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 M.Riva /DiSTAM - UNIMI 27 Chemical preservation • 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 M.Riva /DiSTAM - UNIMI 28 Chilling • 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 M.Riva /DiSTAM - UNIMI 29 Dairying 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. M.Riva /DiSTAM - UNIMI 30 Meat-handling 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 M.Riva /DiSTAM - UNIMI 31 Fish 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 32 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 : 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. M.Riva /DiSTAM - UNIMI 33 Industrial era: the background 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 M.Riva /DiSTAM - UNIMI 34 Live product delivery 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 M.Riva /DiSTAM - UNIMI 35 Natural ice and chilling 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 M.Riva /DiSTAM - UNIMI 36 Freezing 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 M.Riva /DiSTAM - UNIMI 37 Further developments in freezing 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 M.Riva /DiSTAM - UNIMI 38 Ice Cream 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 M.Riva /DiSTAM - UNIMI 39 Freeze Concentration 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 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 M.Riva /DiSTAM - UNIMI 41 Canning 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 M.Riva /DiSTAM - UNIMI 42 The can and the autoclave 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 43 Pasteurization 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 44 Drying 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 M.Riva /DiSTAM - UNIMI 45 Concentrating 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 46 Filtration 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 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 47 Radiation 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 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.