Nutritional Importance of Citrus

Nutritional Importance of Citrus: Citrus is a very valuable plant with a diverse group of species and its fruit is liked all around the world. Pakistan is a big producer of citrus, especially kinnow. Every kind of age peoples are like its fruit variety and use fresh and in processing industry mainly as juice.

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Botanically citrus is a genus of flowering trees and shrubs in the family Rutaceae. Plants in this genus produce citrus fruits including vital types of crops such as lime, lemon, kinnow (mandarins), grapefruit, poemlo, oranges (blood red) etc.


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Citrus plants are native to subtropical and tropical regions of Asia and the Malay Archipelago and they were first domesticated in these areas.

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Citrus are basically large, fleshy, juicy, acidic, and good source of vitamin C. Moreover, citrus does not only contain a large amount of vitamin C but also a rich source of antioxidants, vitamin A, and potassium. Citrus has become an important agricultural product in the Mediterranean Sea, Mexico, and South America. Citrus also contains ascorbic acid which is considered good food for health. One of the best characteristics of the citrus that it has been considered best choices for weight loss program. Generally, citrus fruits are incredible fruits that add additional value to a nutritious diet. Citrus fruits are value able fruits, so we can consume it to overcome micronutrient deficiencies because most people are suffering from obesity and diet-related chronic diseases. Firstly, the citrus fruits wastage was ponded or flushed into the stream, lakes etc. but now the waste is converted into the useful product such as pectin manufacturing, extraction of oil, dried pulp etc. Hence the citrus has been ranked the 2nd worldwide first in Pakistan W.R.T. to its area and production among fruits. Citrus fruits have been long valued for a nutritious diet. The main energy nutrient in citrus is carbohydrate. Fructose, Glucose etc. Citrus fruits contain non-starch polysaccharides (NSP), which is complex with important health benefits. In the body, this polysaccharide holds water-soluble nutrient in a gel which delays emptying and slow digestion and absorption. Potassium also works to maintain the body`s water and acid balance. Some of the nutritional facts about citrus are such as the weight of orange is about (131g), Energy (62kcal), Fiber content (3.1g), Ascorbic acid (70 mg), Folate (40 mcg), Potassium (237). Citrus food may help to reduce the risk of several diseases and disorder such as heart diseases, stroke, cancer, and anemia. Citrus is a good source of fiber, so women should consume of fiber (25 gram) per day and tangerine (1.6 gram) per day. Citrus fruits are hydrating as they contain high water content. Citrus also contains flavonoid plant compound that may promote health. Citrus fruits are used in fruit industry mainly as a gelling agent, thickening agent, and stabilizer. As medicinal values citrus fruits have great importance i.e. against constipation. Diarrhea, Anti-stress, Gastrointestinal problems. Also, in cosmetics products i.e. food flavoring, fragrances in perfume or in the scent industry. People like its fragrance. Also used as insecticides due to the presence of enantiomer. As it is combustible it considers as biofuel. More ever the great benefit of citrus peel has been used in making candies. Dried citrus peel is used in making black tea and simply our home-made tea. Citrus can also enhance meat dishes by putting them in a cavity of the whole chicken before roasting. Moreover, citrus infused vodka being used for an excellent cocktail. Further peels throw in the kindling for making an especially fragrant fire.

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Proceeds from the production or by-products may spell the difference between profit and loss in the citrus canning industry. The three primary by-products of citrus are dried citrus pulp, molasses, and citrus peel oil. The most important utilization of citrus wastes is as stock feed, which consumes large quantities of dried pulp and citrus molasses. Citrus seed oil, alcohol, pectin, bland syrup, and feed yeast have been produced to a lesser extent.

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The term citrus by-product includes numerous by-product feedstuffs which vary according to the originating crop and method of production, that are an important component of ruminant feeding systems in many areas of the world. Citrus fruits are mainly eaten fresh fruit and in processed form as juice. After the juice is extracted from the fruit, there remains a residue comprised of peel (flavedo and albedo), pulp (juice sac residue), rag (membranes and cores) and seeds. These components, either individually or in various combinations, are the source materials from which citrus by-product feedstuffs (BPF) are produced. In India total availability of grape and orange waste is about 2.20 million tonnes.

The fresh citrus pulp waste is palatable to cattle when they are accustomed to the feed and a mature cow can consume about 10 kg per day. Dried citrus pulp has been used as the main energy source for beef cattle and heifers, and up to 45 percent has been used in rations. However, the pulp should not be used at high levels for milking cows as milk production tends to decrease. Digestibility trials with sheep show that its digestibility decreases when the citrus pulp is included at levels more than 30 percent of the ration. It is more advantageous to mix the fresh pulp with partially dried grass or with legumes which cannot be successfully ensiled on their own. To produce seedless or less seeded kinnow and other citrus fruits is a great challenge. Many seeds in kinnow and related types is the main hindrance for Pakistan export.

Role of Microorganisms in Disease Spreading in Citrus

(By Iqra Nazir*, Mujahid Ali**, Ammara Ainee*)

(*IFSN, UOS; **Horticulture, UOS)

Microorganisms are playing a great role in disease spreading in all organisms. They are destroying our citrus production. Citrus is second most produced fruit crop in the world after grapes. Mandarins (Citrus reticulata) are a very important group of citrus, which is the main fruit crop of Pakistan. Fruit drop is a serious threat to citrus industry of Pakistan. Citrus canker is the disease of citrus. The causal organism is Xanthomonas axenopodis P.V citri. This is a bacterium. There are two types of bacteria Gram +ve and Gram-ve bacteria. Xanthomonas is a Gram-ve bacteria. XAC (Xanthomonas axenopodis P.V Citri) enter through stomata in the leaf canopy when stomata open XAC enter the stomata wound 5 directly expose mesophyll tissues due cultural practices and insects. Go to appropriated sites and organs or tissues. Settle and multiply in the organs (infection). Infection is the establishment of the pathogen into the host. After that symptoms appear in the form of the disease. The latent period is involved in it. The time between inoculation to injection is called latent period. Xanthomonas release chemical is known as xanthomonadin which interrupt the normal physiological mechanism of the plant. In the early-stage attack of XAC is high as compared to a later stage. There are 7 to 10 days for symptom appearance after inoculation. symptoms are pinpoints spots that may reach high up to 2 to 10mm size. spots appear first on lower sides than upper sides. spot size depends on the age of injection, type of cultivar and time of inoculation. Raised pustular with definite margin and sunken center deep from the marginal surface. The sunken center is spongy and corky this condition is known as cratriform. Water soaked margins around necrotic tissues which lead to necrosis (death of tissues by autolysis). The yellow halo around each spot-on leaf. It’s fruit and stem lesions size may be up to 1mm.Its vector is citrus leaf miner which forms the galleries on the leaves expose the mesophyll tissues. The biology of the pathogen is Gram –ve, a rod shape, single polar flagellum. The favorable environment is warm, wet condition. The temperature is minimum 20-degree centigrade, optimum 28 to 30-degree centigrade and the maximum is 39-degree centigrade. The spreading method is when it prevails wet condition bacterial ooze come out from bacterial canker spot. Millions of bacteria are present in ooze. Rain and wind spread the ooze and enter through stomata. The pathogen is persistent that can survive for a long time. This pathogen firstly found in Florida USA in 1912. Then in Japan, Africa, Europe epidemic in 30 countries. Citrus Greening is another disease of citrus. It is the 2nd most important disease of citrus.

In China it yellow shoot disease while in Africa it is yellow branch disease, yellow dragon disease. First, it is a belief that it is a viral disease but later discover that it is a bacterial disease Not grow on artificial media. It is phloem-limited bacteria. Casual organism candiddatus liberibacter. It is a rod-shaped bacteria. Citrus psyllid is a vector for it. It acquires from infected source then they transmit to the healthy plants. The citrus psyllid is a sucking insect. They suck on the lower side of the leaf. After acquiring the infected source, it feeds on Lowe side of the leaf. During sucking the plant sap bacteria transmitted into the phloem. Settle down in the phloem and multiply. Established in the phloem (infection). Plant defense will activate. Symptoms appear epidemiology is Asian form can tolerant up to 30 degrees centigrade. African and American form heat sensitive up to 20 to 25 degrees centigrade. Symptoms are yellow shoot, phloem-limited, interrupted with photosynthetic. Yellow foliage half of the fruit remain yellow, uneven fruit ripening.

Citrus malanose is also a disease of citrus. Its causal organism is Diaporthe citri. Symptoms are many dark spots of various sizes merge on fruit and leaf surface. This condition is known as mud cake malanose. Spots on leaves and fruit flow with water on the surface. This condition is known as tear stain malanose. Many spots appear close and form the fruit and leaf surface rough. This condition is known as sandpaper malanose. Citrus malanose is a fungal disease. Citrus gummosis is a disease of citrus in which we can see the gum production on root and trunk. The causal organism of this disease is Phytophthora citrophthora. symptoms are the bark of stem and branches are cracked. From cracks, sap oozing occurs this condition is known as bleeding appearance with the passage of time sap sticks on the stem just like gum. Gum girdle the whole trunk. Bark may be removed easily. Leaves show the nutritional deficiency. Disease life cycle can be described as zoospores moves with the irrigation water then enter the root of the plants, germination and gum formation.

Citrus dieback is a disease of citrus. It is caused by colletotrichum gloeosporidies. Symptoms are it starts drying slowly from top to bottom of branches and twigs. Branches and twigs look like scorched by fire. Minute slightly raised clumps pustules can be seen on affected branches and twigs. Dry twigs look like Ash color.

The blue mold of citrus is caused by Penicillium italicum. Airborne spores that can contaminate and transmit container with movement, packing houses, storage, cleaning equipment and water .it is a post-harvest disease. Symptoms are the blue colored sporulating area on affected fruit. The affected area is surrounding by white mycelium in a narrow range.

The green mold of citrus is caused by Pencilium digitatum. Symptoms are the sporulating area on affected fruit have olive green spores. The affected area is surrounded by broad zone with whitish mycelium. A brush like structure can be seen under microscope known as penicillus brush. Citrus stubborn disease caused by bacteria which is phloem-limited. The causal organism of this disease is Spiroplasma citri. The vector of this leafhopper which is sucking, phloem-limited. Symptoms are an irregularity in fruit arrangement on same plant shape, size, and color. Affected fruit drop out. Irregularity in affected fruit can be seen by cutting into two halves. Bunchy appearance on the top of the affected fruit. There two ends of fruits blossom end green and stem end discolored.

Citrus variegated chlorosis is caused by organism Xylella fastidiosa. It is a xylem limited bacterium. So, it is a bacterial disease. The vector of this disease is sharpshooter leafhopper. it is a sucking insect suck the sap from xylem. Acquisition feeding period is 2 hours. It has a wide host range. It has several generations per year. Symptoms on leaves are interveinal (between the veins) chlorotic lines. Gummy lesions on lower sides of the leaf. Gummy lesions become black and necrotic. Symptoms of fruits look like damage, changed color, the rind is held, lack of juice and acidic flavor. Symptoms of the tree are reducing vigor and growth with abnormal fruit and flower setting. In this way not only, fruit yield but also fruit quality in decreasing in citrus.

Enhancement of Citrus Processing is Urgent Need in Pakistan

(By Neha Anwar, Dr. Tusneem Kausar, Dr. Farzana Siddique)

(Institute of Food Science and Nutrition, UOS)

Pakistan is famous for its citrus production, especially kinnow is at the top. Sargodha region is well known for its production all over the world that why it is called California of Pakistan. Citrus is noteworthy among fruits due to Vitamin C. Basically, an orange consists of juice vesicles surrounded by a waxy skin, the peel. The peel comprises a thin, color outer layer called the flavedo and a thicker, fibrous inner layer called the albedo. The endocarp, the edible portion of the fruit, includes a central fibrous core and individual segments containing the juice sacs. In large processing plants, the complete fruit is utilized. By-products are produced to help maximize profits and minimize waste. Four groups of fruit are of commercial significance in the production of orange juice products i.e., the sweet orange, also known as the China orange, Citrus sinensis, is commonly called sweet orange, the sour or bitter orange, also known as the Seville orange, Citrus aurantium. Sourness in citrus is due to citric acid that makes it unique. The mandarin orange and tangerine varieties Citrus reticulate. Hybrid oranges (tangors) that result from various crosses between tangerines and sweet oranges. Of these, the sweet orange is by far the most important. In several markets, including Europe, only juice made from sweet orange varieties, Citrus sinensis, may be labeled as orange juice. To be correct from a horticultural perspective, the common name for the species Citrus reticulata is mandarin, some varieties of which are called tangerines. However, the word tangerine is often used as the common species name. It is important for the orange processing industry to get the maximum number of products from the fruit while maintaining their high quality. The other products and by-products of citrus are as following they may be primary and secondary. Lemon is a species of citrus that is used in pickles.

Its primary product is fresh fruit;

In industry, after picked, the fruits go through inspection stages, washing, waxing and packing. The cleanser used during washing may include fungicides, therefore the fruits are not sent to juice processing, since the fungicides could find their way into the juice, leaving undesirable residues.

Main industrial processing use is its juice;

which can be divided into two categories like frozen concentrate orange juice (FCOJ) which can be transported at a lower cost and it can also store for longer periods in frozen drums. Not from concentrate juice (NFCJ) not undergone concentration process and export as well. There are various secondary products like comminuted Citrus Base Originally developed in the United Kingdom, it is a product made by milling the whole fruit or by mixing the milled peel with juice concentrate. It is used as an ingredient for fruit drinks, since it has a strong flavor. Pulp or Orange Cells; Ruptured juice sacs and segment walls recovered after the extraction process. Can be added back to the juice to provide mouthfeel and a natural appearance to the product. Pulp wash also known as WESOS – Water-Extracted Soluble Orange Solids; the juice obtained after the pulp is washed, containing fruit solids. May be used in fruit drinks as a source of secondary soluble solids and fruit solids. It is also used as a clouding agent to provide body and mouthfeel to fruit drinks wash. Peel oil or cold-pressed oil can be extracted. Essential oil extracted from the orange peel. It is usually sold to the flavor industry which produce flavors largely used in food, drinks, cosmetics and chemical products. Essences; The essences comprise volatile components recovered from the evaporation process, separated in aqueous and oil phases. The water-soluble components are sometimes added-back to the concentrate juice, and the oil phase is different from the peel oil, containing more of the fruit flavor; it is also added back to the concentrate. Both phases are raw material for food and beverage industries. D-Limonene contains the main component of the peel oil. It is a thin and transparent oil obtained from the manufacturing of citrus pulp pellets, used in the biodegradable solvents and cleaning products and in the manufacturing of synthetic resins and adhesives.  A famous company Baker’s Land is making lemon flavor delicious biscuits. Citrus Pulp Pellets; this product results from processing the juice and is made from wet waste products of the fruit: peel, bagasse, non-reutilized pulp, and seeds. These waste products go through a drying process and form a concentrated forage that is transformed into pellets, serving as preparation to cattle ration. Pectin; A less common product, obtained from orange peel and used as thickener in jellies, marmalades and gelatin. Nutritional value of oranges is; 1 cup of orange segments contain calories 8, fat 0g, protein 2g, carbohydrates 21g/ 7% DV, fiber 4g/ 17% DV, vitamin C 95.8mg/ 160% DV, folate 54.0mcg/ 14% DV, thiamine 0.2mg/ 10% DV, potassium 326mg / 9% DV. Health benefits of oranges are; Nutrients in oranges are plentiful and diverse. The fruit is low in calories, contains no saturated fats or cholesterol, but rich in dietary fiber, Pectin, by its virtue as a bulk laxative, helps protect the mucosa of the colon by decreasing its exposure time to toxic substances as well as by binding to cancer-causing chemicals in the colon. By binding to bile acid in the colon, pectin has also been shown to reduce blood cholesterol levels by decreasing its re-absorption in the colon. Now a day orange flavor is famous for drinks, biscuits and sent or in perfumes etc. We have a challenge to safe our wasting produce. It surplus supply during glut season would make thinkers a contest. So, it is an urgent need to improve its processing industry.

ROLE OF PRUNING IN CITRUS, TIMING AND ITS IMPACT ON TREE AND FRUIT

*Muhammad Shafique Khalid, *Muhammad. Amin, *Omer Hafeez, **Muhammad Umar and **Faheem Haider

* PhD Scholar, Institute of Horticultural Sciences, University of Agriculture Faisalabad

** M.Sc Scholar Institute of Horticultural Sciences, University of Agriculture Faisalabad

Pruning fruit trees is a technique that is employed by gardeners to control growth, remove dead or diseased wood or stimulate the formation of flowers and fruit buds. Pruning of tree fruits and vines is a horticultural practice handed down from ancient time. It has in common the objectives of manipulating various aspects of vegetative and fruiting behaviour. Some of the benefits traditionally attributed to pruning and girdling in the practical culture of citrus have been called into question by field research in the past few decades.

PRUNING IN CITRUSCitrus is a perennial crop. As long as the trees remain healthy, they can flower and fruit for years on end, some times for as long as twenty or thirty years (Mazhar and Nawaz, 2006). However, if the trees are not maintained at a proper size, the height and canopy shape of mature trees in a citrus orchard will not be uniform and the branches will be too crowded. In a crowded orchard, disease and pests can spread quickly. Fruit quality tends to be poor, and trees may not bear fruit every year. A proper training and pruning program is essential for the maintenance of a healthy and productive orchard.

Benefits of pruning in citrus

The major benifits of pruning in citrus include:

  1. The total effective leaf area is increased resulting in increased photosynthesis by exposing the leaves to light and air.
  2. The water use efficiency and the conversion of available plant nutrients is increased.
  3. By removing diseased or infested branches and exposing leaves to light and air, a good training and pruning program helps control pests and diseases in citrus orchard.
  4. Proper pruning of the tree keeps it in the right size.
  5. It also increases the vigor of the tree, enhances its tolerance of various stresses, and helps maintain the most efficient balance between vegetative growth and fruiting.

Pruning and skirting (removal of low-hanging limbs) affects on canopy temperature, relative humidity (RH), and fruit yield and quality of Orlando’ tangelo trees (Citrus paradisi Macf. x Citrus reticulata Blanco). Pruning increased the percentage of large fruit and reduced the percentage of small fruit. (Morales et al., 2000).

The alternate tendency exists across all varieties of the citrus. To attenuate alternate bearing, pruning and fertilization are processes the only options which growers can exploit. For pruning to be effective, it must be done after the end of an “off” or light crop year, i.e., prior to the season of anticipated high production. It should not matter whether the pruning is conducted before or after the bloom, as the results should be about the same, reduction in production during the season following pruning (Mazhar and Nawaz, 2006).

Eissenstat and Duncan (1992) reported that total reducing and ketone sugars (free fructose, sucrose and fructans) in the fine roots were less in pruned than unpruned trees 20 days after pruning, but not thereafter. By 30 days after pruning, at least 20% of the roots of the pruned trees at a soil depth of 9 to 35 cm apparently died. By 63 days after pruning, root length density had recovered to that of the unpruned trees, although starch reserves were 18% less in the fine roots of pruned than unpruned trees at this time.

Growers should select the correct time for the pruning. Since citrus trees are evergreen, they do not have a period of true dormancy. However, the metabolism of the tree is less active in the period after fruit harvesting. This period of reduced metabolism activity is the time to prune. Light pruning can also be conducted at other seasons to remove unwanted and overcrowded shoots.

Tree age is another important factor that should be taken into account, because the tree’s response to pruning varies according to age (Mazhar and Nawaz, 2006). Therefore citrus growers have to recognize the characteristics of the different cultivars they are growing in order to select the best training and pruning system for their orchards.

References:

Eissenstat D.M and L.W Duncan.1992. Root growth and carbohydrate responses in bearing citrus trees following partial canopy removal. Tree Physiol. 10(3): 245-57.

Mazhar, M.S. and M.A. Nawaz. 2006. Pruning as a tool to improve yields in citrus. Pakistan Horticulture. 4(1): 23-25.

Morales, P., F.S. Davies and R.C Littell. 2000. Pruning and skirting affect canopy microclimate, yields, and fruit quality of ‘Orlando’ tangelo. Hort Science. 35: 30-35.

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