Department of microbiology microbial food technology group a diploma in quality assurance in microbiology diploma



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Subspecies


There are at least five natural subspecies distributed over a wide range:

  • Olea europaea subsp. europaea (Europe)

  • Olea europaea subsp. cuspidata (from Eritrea and Ethiopia south throughout East Africa, also in Iran to China)

  • Olea europaea subsp. guanchica (Canaries)

  • Olea europaea subsp. maroccana (Morocco)

  • Olea europaea subsp. laperrinei (Algeria, Sudan, Niger, India)

Cultivars


Small Olive Tree



Large Olive Tree



Olive Tree Leaves



Olive Tree Trunk



Olive Flowers



A young olive plant, germinated from a seed



Monumental tree in Apulia Region - Southern Italy



There are thousands of cultivars of the olive. In Italy alone at least three hundred cultivars have been enumerated, but only a few are grown to a large extent. The main Italian cultivars are 'Leccino', 'Frantoio' and 'Carolea'. None of these can be accurately identified with ancient descriptions, though it is not unlikely that some of the narrow-leaved cultivars most esteemed may be descendants of the Licinian olive. The Iberian olives are usually cured and eaten, often after being pitted, stuffed (with pickled pimento, anchovies, or other fillings) and packed in brine in jars or tins.

Since many cultivars are self sterile or nearly so, they are generally planted in pairs with a single primary cultivar and a secondary cultivar selected for its ability to fertilize the primary one, for example, 'Frantoio' and 'Leccino'. In recent times, efforts have been directed at producing hybrid cultivars with qualities such as resistance to disease, quick growth and larger or more consistent crops.



Some particularly important cultivars of olive include:

  • 'Manzanillo', a large, rounded-oval fruit, with purple-green skin. Rich taste and thick pulp. A prolific bearer, grown around the world.

  • 'Frantoio' and 'Leccino'. These cultivars are the principal participants in Italian olive oils from Tuscany. Leccino has a mild sweet flavour while Frantoio is fruity with a stronger aftertaste. Due to their highly valued flavour, these cultivars are now grown in other countries.

  • 'Arbequina' is a small, brown olive grown in Catalonia, Spain, good for eating and for oil.

  • 'Empeltre' is a medium-sized black olive grown in Spain, good for eating and for oil.

  • 'Kalamata' is a large, black olive with a smooth and meatlike taste, named after the city of Kalamata, Greece, used as a table olive. These olives are usually preserved in vinegar or olive oil. Kalamata olives enjoy PDO (Protected designation of origin) status.[13]

  • 'Koroneiki' originates from the southern Peloponese, around Kalamata and Mani in Greece. This small olive, though difficult to cultivate, has a high yield of olive oil of exceptional quality.

  • 'Pecholine' or 'picholine' originated in the south of France. It is green, medium size, and elongated. The flavour is mild and nutty.

  • 'Lucques' originated in the south of France (Aude département). They are green, large, and elongated. The stone has an arcuated shape. Their flavour is mild and nutty.

  • 'Souri' (Syrian) originated in Lebanon and is widespread in the Levant. It has a high oil yield and exceptionally aromatic flavour.

  • 'Nabali' is a Palestinian cultivar[14] also known locally as 'Baladi', which along with 'Souri' and 'Malissi' are considered to produce among the highest quality olive oil in the world.[15]

  • 'Barnea' is a modern cultivar bred in Israel to be disease-resistant and to produce a generous crop. It is used both for oil and for table olives. The oil has a strong flavour with a hint of green leaf. Barnea is widely grown in Israel and in the southern hemisphere, particularly in Australia and New Zealand.

  • 'Maalot' (Hebrew for merits) is another modern Israeli, disease-resistant, Eastern Mediterranean cultivar derived from the North African 'Chemlali' cultivar. The olive is medium sized, round, has a fruity flavour and is used almost exclusively for oil production.

  • 'Mission' originated on the California Missions and is now grown throughout the state. They are black and generally used for table consumption.

Growth and propagation


Olive trees show a marked preference for calcareous soils, flourishing best on limestone slopes and crags, and coastal climate conditions. They tolerate drought well, thanks to their sturdy and extensive root system. Olive trees can be exceptionally long-lived, up to several centuries, and can remain productive for as long, provided they are pruned correctly and regularly.

The olive tree grows very slowly, but over many years the trunk can attain a considerable diameter. A. P. de Candolle recorded one exceeding 10 m in girth. The trees rarely exceed 15 m in height, and are generally confined to much more limited dimensions by frequent pruning. The yellow or light greenish-brown wood is often finely veined with a darker tint; being very hard and close-grained, it is valued by woodworkers.

The olive is propagated in various ways, but cuttings or layers are generally preferred; the tree roots easily in favourable soil and throws up suckers from the stump when cut down. However, yields from trees grown from suckers or seeds are poor; it must be budded or grafted onto other specimens to do well (Lewington and Parker, 114). Branches of various thickness are cut into lengths of about 1 m and, planted deeply in manured ground, soon vegetate; shorter pieces are sometimes laid horizontally in shallow trenches, when, covered with a few centimetres of soil, they rapidly throw up sucker-like shoots. In Greece, grafting the cultivated tree on the wild form is a common practice. In Italy, embryonic buds, which form small swellings on the stems, are carefully excised and planted beneath the surface, where they grow readily, their buds soon forming a vigorous shoot.

Occasionally the larger boughs are marched, and young trees thus soon obtained. The olive is also sometimes raised from seed, the oily pericarp being first softened by slight rotting, or soaking in hot water or in an alkaline solution, to facilitate germination.

Where the olive is carefully cultivated, as in Languedoc and Provence, the trees are regularly pruned. The pruning preserves the flower-bearing shoots of the preceding year, while keeping the tree low enough to allow the easy gathering of the fruit. The spaces between the trees are regularly fertilized. The crop from old trees is sometimes enormous, but they seldom bear well two years in succession, and in many instances a large harvest can only be reckoned upon every sixth or seventh season.

A calcareous soil, however dry or poor, seems best adapted to its healthy development, though the tree will grow in any light soil, and even on clay if well drained; but, as remarked by Pliny, the plant is more liable to disease on rich soils, and the oil is inferior to the produce of the poorer and more rocky ground.

In general, a temperature below 14 °F (-10 °C) may cause considerable injury to a mature tree, but (with the exception of juvenile trees) a temperature of 16 °F (-9 °C) will normally cause no harm.

Fruit harvest and processing


Most olives today are harvested by shaking the boughs or the whole tree. Another method involves standing on a ladder and "milking" the olives into a sack tied around the harvester's waist.Using olives found lying on the ground can result in poor quality oil.

In southern Europe the olive harvest is in winter, continuing for several weeks, but the time varies in each country, and also with the season and the kinds cultivated. A device called the oli-net wraps around the trunk of the tree and opens to form an umbrella-like catcher; workers can then harvest the fruit without the weight of the load around their neck. Another device, the oliviera, is an electronic tool that connects to a battery. The oliviera has large tongs that are spun around quickly, removing fruit from the tree. This method is used for olives used for oil. Table olive varieties are more difficult to harvest, as workers must take care not to damage the fruit; baskets that hang around the worker's neck are used.

The amount of oil contained in the fruit differs greatly in the various cultivars; the pericarp is usually 60–70% oil. Typical yields are 1.5-2.2 kg of oil per tree per year.

Traditional fermentation


Olives freshly picked from the tree contain phenolic compounds and oleuropein, a glycoside which makes the fruit unpalatable for immediate consumption. There are many ways of processing olives for table use. Traditional methods use the natural microflora on the fruit and procedures which select for those that bring about fermentation of the fruit. This fermentation leads to three important outcomes: the leaching out and breakdown of oleuropein and phenolic compounds; the creation of lactic acid, which is a natural preservative; and a complex of flavoursome fermentation products. The result is a product which will store with or without refrigeration.

One basic fermentation method is to get food grade containers, which may include plastic containers from companies which trade in olives and preserved vine leaves. Many bakeries also recycle food grade plastic containers which are well sized for olive fermentation; they are 10 to 20 litres in capacity. Freshly picked olives are often sold at markets in 10 kg trays. Olives should be selected for their firmness if green and general good condition. Olives can be used green, ripe green (which is a yellower shade of green, or green with hints of color), through to full purple black ripeness. The olives are soaked in water to wash them, and drained. 7 litres (which is 7 kg) of room temperature water is added to the fermentation container, and 800 g of sea salt, and one cup (300g) of white vinegar (white wine or cider vinegar). The salt is dissolved to create a 10% solution (the 800 g of salt is in an 8 kg mixture of salt and water and vinegar). Each olive is given a single deep slit with a small knife (if small), or up to three slits per fruit (if large, eg 60 fruit per kg). If 10 kg of olives are added to the 10% salt solution, the ultimate salinity after some weeks will be around 5 to 6% once the water in the olives moves into solution and the salt moves into the olives. The olives are weighed down with an inert object such as a plate so they are fully immersed and lightly sealed in their container. The light sealing is to allow the gases of fermentation to escape. It is also possible to make a plastic bag partially filled with water, and lay this over the top as a venting lid which also provides a good seal. The exclusion of oxygen is useful but not as critical as when grapes are fermented to produce wine. The olives can be tasted at any time as the bitter compounds are not poisonous, and oleuropein is a useful antioxidant in the human diet.

The olives are edible within 2 weeks to a month, but can be left to cure for up to three months. Green olives will usually be firmer in texture after curing than black olives. Olives can be flavored by soaking them in various marinades, or removing the pit and stuffing them. Herbs, spices, olive oil, feta, capsicum (pimento), chili, lemon zest, lemon juice, garlic cloves, wine, vinegar, juniper berries, and anchovies are popular flavorings. Sometimes the olives are lightly cracked with a hammer or a stone to trigger fermentation. This method of curing adds a slightly bitter taste.

16.Write a brief note on Tempeh Production.

Tempeh is a nutritional super hero. It is high in protein, dietary fiber, iron, potassium, calcium, and phytochemicals like isoflavones. It has been shown to lower cholesterol, high blood pressure and the risk of heart attack and stroke; reduce the risk of some cancers, like colon, breast, ovarian and prostate; ease certain menopausal symptoms; prevent and possibly even reverse the effects of osteoporosis and diabetes. To obtain these protective properties, researchers recommend consuming a minimum of 25 grams soy protein and 30-50 milligrams isoflavones daily. This works out to about 1-2 servings a day. One serving of tempeh, which is 1/2 cup (4 ounces), provides on average 19 grams soy protein, 60 milligrams isoflavones and 7 grams dietary fiber (28% RDA). Tempeh made with only soybeans has more soy protein and isoflavones than those with added grain. Whatever variety you choose, tempeh is the best source and easiest way to get lots of high quality protein, isoflavones and fiber in a minimally processed soy food. Each serving also supplies about 100 milligrams calcium (10% RDA), 550 milligrams potassium (16% RDA), and 5 milligrams iron (30% RDA).

2. Tempeh is a great choice for people who have difficulty digesting plant-based high-protein foods like beans and legumes or soy foods such as tofu. Because tempeh is a fermented soy product, its enzymes are partially broken down, making it easier to metabolize. It does not produce the unpleasant gastrointestinal discomfort and gas that some other plant-based proteins do. This fermentation process actually allows your body to more easily assimilate and absorb tempeh's nutrients. Besides being a terrific cholesterol-free easy-to-digest meat alternative, it is also ideal for people on low sodium diets. Unlike other fermented soy products, like miso which is very salty, tempeh is extremely low in sodium.

3. Tempeh has a pleasant, wonderfully unique nutty/mushroom flavor. It's rich and savory taste and firm texture makes it easy to create fantastic meals without a lot of fuss. It does not need much preparation or cooking time, making it a marvelously healthy fast food. Just add a little soy sauce or liquid hickory smoke seasoning to enhance its flavor. Then stir-fry, sauté, microwave, stew or bake it to make a variety of delightful dishes and sandwiches. To make a hearty entree in a short amount of time, all you need is tempeh, onions, mushrooms, peppers, olive oil, liquid seasoning, and some cooked brown rice or pasta. Thinly slice the tempeh. Sprinkle some soy sauce or liquid hickory (or mesquite) smoke seasoning on both sides of the slices. Slice the onions, mushrooms and peppers, and sauté in a little olive oil for a few minutes. Add the seasoned tempeh slices and sauté until lightly browned. Salt and pepper to taste.


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