Fruit and Vegetable Technology

8/3/2019 Fruit and Vegetable Technology

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have an important place in our day-to-day life. are called protective foods. India is one of the largest producers of fruits and

vegetables in the World Indias geographical location and topography provides

an excellent opportunity to produce every thing in ourcountry.

round the year availability of fruits and vegetablesprovides passive response towards commercialprocessing .

people also have poor acceptability of processed foods. often led to glut, more post harvest losses besides less

contribution of processed foods a considerable amount of this produce in lost due to

negligence and improper post harvest handling, which

amounts to be 25 to30%

.


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our country is one of the highest producer of thefruits and vegetables but productivity issignificantly lower in most of the fruits andvegetables as per the international bench mark .

The lower yields are mainly due to poor quality ofplanting material including varieties, unplannedfarm management practices like fertilizer, watermanagement and small farm holding.

One of the reason is the varieties have poor

recovery of process product for i.e. Indiantomatoes have 4o Bx of total solids whereasvarieties in European countries have 6 oBx. Thus,to produce same quantity of tomato end product50% more tomatoes are required in our country.


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Fruits and vegetables processing industryranks 5th in its size

Annual turnover of fruit and vegetable

industry is Rs. 1800 billion and out of which Rs.1400 billion are from unorganized sector.

Importance of fruits and vegetables:

Employed in the preparation of preserves, in

cooking and in fermented and non fermentedbeverages

Rich source of carbohydrate, minerals, vitaminsand dietary fibre


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Dietary fibre has both direct and indirectadvantages.

Provide a variety in taste, interest and aestheticappeal.

Role of fibre in minimizing the occurences ofhealth diseases related with affluent life style.

Benefits relate to role in kidney function,prevention of cancer and cardiac disordersthrough its contribution of ascorbic acid, betacarotene and non starch polysaccharides

Carotene and vitamin C are known for reducingthe cancer risks by enhancing the tumorsurveillance by immune system.


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Fruits and vegetables are living organisms and arehighly perishable

No. of factors result in postharvest spoilage. Physical causes of post harvest spoilage: Loss of moisture, causing wilting/shrinkage Loss of stored energye.g. carbohydrates Loss of other food constituents e.g. vitamins Physical losses through pest and disease attack Loss of quality due to physiological disorders Greening (potatoes) Seed germination Root or shoot growth


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The fruit is derived from the Latin word fructose whichmeans to enjoy, produce.

The fruit is a product of fertilization and is a ripened ovary. Fruits are classified into :

pome (apple and pear); stone (mango, peach, plum, cherry), berry (strawberry, tomato); nut (walnut, cashewnut); hesperidium (citrus);

synconium (fig), sorosis (mulberry); coenocarp (jack fruit) and syncarp (custard apple).


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The vegetables develop from variety of plantparts (cabbage pea, potato).

On the basis of plant parts used as vegetables

they are grouped as: fruits (gourds, brinjal, capsicum);

stem (asparagus, amaranths),

leaves (cabbage, lettuce, spinach)

flowers (broccoli, cauliflower) and

underground portion (radish, carrot, potato,onion, garlic).


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For processing or storage purpose fruits are alsoclassified as climacteric and non-climacteric fruits.

The climacteric fruits are those, which develop totalsenescence sometime after the harvest during storage.

For e.g. apple, banana, ber, fig, guava, mango, pear,peach, papaya, sapota, tomato. Whereas non-climacteric fruits ripen on the plants. for

i.e. citrus, grape, litchi, pineapple, pomegranate,strawberry etc.

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he climacteric fruits have high rate of respiration andproduction of carbon dioxide and ethylene than thenon-climacteric fruits during the process of ripening.

It leads to change in colour, flvaour, texture and somechemical changes.


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Cell WallCell wall is the outermost tough and rigid layer,which comprises cellulose, hemicellulose, pectin and

at other times, lignin. The prime functions of cellwall are protection, giving structural support .

Cell MembraneCell membrane, also called plasma membrane, ispresent inside the cell wall and surrounds the

cytoplasm. It connects the intracellular components(organelles and cytoplasm) with the extracellularenvironment, and helps in protection andtransportation. The cell membrane is permeable tospecific substances only.


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Plasmodesmata

Plasmodesma (plural plasmodesmata) is a small opening,which connects plant cells with each other. this connectingchannel enables transport of materials and allowscommunication between the cells. In a single plant cell,about 1,000-100,000 plasmodesmata are present.

Nuclear Membraneit is the outer covering of the nucleus. It separates thecytoplasmic contents from the nuclear contents. minutepores (nuclear pores) are present for exchanging materialsbetween the nucleus and cytoplasm.

Nucleus

Nucleus is a specialized organelle, which contains theplant's hereditary material i.e. DNA (DeoxyribonucleicAcid). Inside the nucleus, a dense, spherical body callednucleolus is present. The nucleus contains structures, whichregulates the cell cycle, growth, protein synthesis andreproductive function.


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VacuoleVacuoles are large membrane-bound compartments, whichstore water and compounds. They function as storage,excretory and secretory organelles. The membranesurrounding a vacuole is called tonoplast. A mature plantcell has a single vacuole at the near center of the cell (centralvacuole), which contributes to about 30-80 percent of thecell's volume.

CytoplasmCytoplasm is filled up by cytosol, which is a gelatinous and

semitransparent fluid. All the organelles of the plant cell arepresent in this cytoplasm. This part of the plant cell is thesite for cell division, glycolysis and many other cellularactivities.

Plastid (Chloroplast)

Plastids are organelles responsible for photosyntheticactivity, manufacturing and storage of chemical compoundsin plants. Chloroplast is an important form of plastidcontaining chlorophyll pigment, which helps in harvestinglight energy and converting it to chemical energy. Likewise,chromoplast and other plastids are present in a plant cell.


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MitochondriaMitochondria (singular mitochondrion) are oblong shapedorganelles, which are also known as 'the powerhouse of the cell'.They are responsible for breaking down complex carbohydrate

and sugar molecules to simpler forms, which the plants can use.EndoplasmicReticulumThe endoplasmic reticulum (ER) organelle plays a major role inmanufacturing and storage of chemical compounds, like glycogenand steroids. It is also involved in translation and transportationof protein. ER is also connected to the nuclear membrane, so as tomake a channel between the cytoplasm and the nucleus.Golgi ApparatusIt is an organelle responsible for processing of macromolecules(like carbohydrates, proteins and fats) and packaging them intomembrane-bound vesicles for transportation purposes. Golgi

bodies are present near to the nucleus of the plant cell.RibosomeRibosomes are organelles, which are made up of 60% RNA(Ribonucleic Acid) and 40% protein, and play an important role inprotein translation. main site of protein synthesis is ribosome.


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MicrobodiesMicrobodies are single, membrane-bound, globular shapedorganelles, which are found in the cytoplasm. They range insize from 0.5-1 micrometer, and contain degradativeenzymes.Many kinds of microbodies are present in a plant

cell, of which the two most common types are peroxisomesand glyoxysomes.MicrotubulesMicrotubules are straight, hollow, tubular cylinders, whichare major elements of the cytoskeleton. These plant cellstructures are involved in synthesizing cell wall. Function

wise, they are crucial for structural support, cell divisionand transport of vesicles.Microfilamentsthe microfilaments are responsible for giving structuralsupport, flexibility and shape to the cell.


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Water: The body has three sources of water: (1)ingested water and beverages, including fruit juices, (2)the water content of solid foods, and (3) metabolicwater.

Fruits have a high percentage of water that ranges from70% to 95% of the eatable part of the fruit . For this

reason, they are, together with vegetables, a very goodsource of water in the diet within the solid foods.

The content of water in a fruit may be greatly affectedby the processing technology,some technologies used to increase the shelf life offruits do so through the reduction of their watercontent.

water content of a fruit also changes duringmaturation,


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carbohydrates are the main component of fruitsand vegetables and represent more than 90% oftheir dry matter.

The main monosaccharides are glucose andfructose.

Their concentration may change depending on

the degree of maturation of the fruit. Other monosaccharides, such as galactose,

arabinose, and xylose, are present in minimalamounts


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Sucrose is the most abundant oligosaccharide infruits;

Starch is present in very low amounts in fruits,since its concentration decreases during

maturation. The only exception is banana that may have

concentrations of starch higher than 3% During food processing, carbohydrates are mainly

involved in two kinds of reactions: on heating they darken in color or caramelize, and some of them combine with proteins to give

dark colors known as the browning reaction.


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Fiber is often referred to as unavailablecarbohydrate.

The major components of dietary fiber are the

polysaccharides celluloses, hemicelluloses,pectins, gums, and mucilages.

classified as water soluble and insoluble.

Gums, mucilages, some hemicelluloses, andpectins are part of the soluble fiber.

Celluloses, hemicelluloses, and lignins areinsoluble fibers.


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Dietary fiber is present in fruits in amounts thatmay be as high as 7% of the eatable part of thefruit

Fat : Fat content in fruits is in general very low. However, avocado (1216%), the lipid levels

are higher.

In avocado, the most abundant fatty acids are

palmitic, palmitoleic,stearic, oleic, linoleic, andlinolenic acids, but the amounts may change alot with the variety, maturity, processing, andstorage conditions


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Proteins: Nitrogenated compounds are presentin fruits in low percentages (0.11.5%).

From a quantitative point of view, fruits are not

a good source of proteins,

however, in general berries are a better sourcethan the rest of the fruits.


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VITAMIN C: Vitamin C is an essential nutrient forhumans; we cannot synthesize vitamin C, andtherefore must acquire it from the diet.

For adults, dietary needs are met by a minimum

intake of 60 mg/day. The primary contributors to daily vitamin intake

are fruit juices (21% of total), whereas all fruitstogether contributed nearly 45% of total vitamin Cintake.

Relatively high amounts of vitamin C are found instrawberries and citrus fruits, although theavailability of vitamin C within these food sourceswill be influenced by numerous factors.


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rich sources of vitamin C are blackcurrant (200mg/100 g), strawberry (60 mg/100 g), and thecitrus fruits (3050 mg/100 g).

Vitamin E : Vitamin E is the generic term for afamily of related compounds known astocopherols and tocotrienols.

The richest sources of vitamin E are vegetable oils

and the products made from them, followed bybread and bakery products and nuts.

Vegetables and fruits contain little amount ofvitamin E


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Thiamin (vitamin B-1), riboflavin (vitamin B-2),niacin (vitamin B-3), and pyridoxine (vitamin B-6),are used as coenzymes in all parts of the body.

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hey participate in the metabolism of fats,carbohydrates, and proteins.

They are important for the structure and functionof the nervous system

Minerals : An adequate intake of minerals isessential for a high nutritional quality of the diet,

it also contributes to the prevention of chronicnutrition related diseases.


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Iron : Iron (Fe) is an essential nutrient thatcarries oxygen and forms part of the oxygen-carrying proteins, hemoglobin in red blood

cells and myoglobin in muscle. It is also a necessary component of various

enzymes.

Body iron is concentrated in the storage forms,

ferritin and hemosiderin, in bone marrow,liver, and spleen.

Body iron stores can usually be estimated fromthe amount of ferritin protein in serum.


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The main inhibitory substances are phytic acidfrom cereal grains and legumes such as soy,and polyphenol compounds from beverages

such as tea and coffee. The main enhancers of iron absorption are

ascorbic acid from fruits and vegetables, andthe partially digested peptides from muscle

tissues


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Approximately 99% of total body calcium is inthe skeleton and teeth, and 1% is in the bloodand soft tissues.

The dietary recommendations vary with age.An amount of 1300 mg/day for individualsaged 918 years, 1000 mg/day for individualsaged 19 50 years, and 1200 mg/day forindividuals over the age of 51 years.

Calcium is present in variable amounts in allthe foods and water we consume, althoughvegetables are one of the main sources.


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Phosphorus (P) is an essential mineral that is found inall cells within the body.

The body of the human adult contains about 400500 g.

The greatest amount of body phosphorus can be foundprimarily in bone (85%) and muscle (14%).

Phosphorus is primarily found as phosphate (PO42).

The inorganic constituents of bone are primarily acalcium phosphate salt.

for youth 918 years, the RDA is 1250 mg, whichindicates the higher need for phosphorus during theadolescent growth. Adults 19 years and older have aRDA of 700 mg


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Magnesium (Mg) is the fourth most abundantcation in the body, with 60% in the bone and 40%distributed equally between muscle and non-muscular soft tissue. Only 1% of magnesium isextracellular.

Magnesium has an important role in at least 300fundamental enzymatic reactions

it has a key role in neurotransmission and immune

function. The RDAs for magnesium are 320 and 420 mg/day

for women and men (adults over 30 years),respectively


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Potassium (K) in the form of K+ is the mostessential cation of the cells.

Its high intracellular concentration is regulated

by the cell membrane through the sodiumpotassium pump.

Most of the total body potassium is found inmuscle tissue

The estimated minimum requirement forpotassium for adolescents and adults is 2000mg or 50 mEq/day. The usual dietary intakefor adults is about 100 mEq/day


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Carotenoids : are lipid-soluble plant pigmentscommon in photosynthetic plants.

- and carotene,lutein, lycopene zeaxanthin,

and - and cryptoxanthin are mostcommonly consumed and are most prevalentin human plasma


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The most common sterols in fruits are -sitosterol, and its 22-dehydro analogue stigmasterol, campesterol andAvenasterol

Plant sterols are not endogenously synthesized in humans,therefore, are derived from the diet entering the body onlyvia intestinal absorption.

Since plant sterols competitively inhibit cholesterolintestinal uptake, a major metabolic effect of dietary plantsterols is the inhibition of absorption and subsequentcompensatory stimulation of the synthesis of cholesterol.

The ultimate effect is the lowering of serum cholesterol Consequently, the higher the dietary intake of plant sterols

from the diet, the lower is the cholesterol absorption and thelower is the serum cholesterol level


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Fruits and vegetables are highly perishablecommodities with active metabolism duringthe post-harvest period.

On removal from the parent plant, vegetativeparts, such as fruits, roots, stems etc aredeprived of their normal supply of minerals,water, and also in some instances, simple

organic molecules [e.g. sugars, hormones] thatnormally would be translocated from otherparts of the plant.


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Although the photosynthetic activity is negligible,most tissues remain capable of transforming many ofthe constituents already present in them.

The kind and intensity of physiological activity in

detached plants determines their storage longevity. Some plant parts, such as seeds, fleshy roots, tubers,

bulbs are morphologically and physiologically adaptedto maintain the tissue in a dormant state untilenvironmental conditions are favourable forgermination or growth.

Metabolic activity, though depressed, is notcompletely halted in such tissues.

Fleshy fruits are unusual in that maturation is followedby a ripening process, which is associated with thedevelopment of optimal eating quality.


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Carbohydrate : Sugars are important for pleasingfruit flavour (sugar acid ratio), attractive colourand texture.

As the ripening starts these sugars undergometabolic transformation both quantitatively andqualitatively.

Most of the soluble carbohydrates are metabolizedcompletely as the fruit ripens.

Pectic substances and cellulose are the reservecarbohydrates that also serve as potential sourcesof acids, sugars and other respiratory substancesduring ripening.


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Green or raw fruit usually contains starch inabundance, but is short in soluble sugars thatprovides sweetness to it.

During ripening, the starch is enzymatically[hydrolysis by alpha- and beta-amylases]converted into sugars.

Thus, the major bulk of carbohydrate fractionof a fully ripened fruit consists of sugars. Thesugars commonly found in fruits are glucoseand fructose [invert sugars] and sucrose.


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Organic Acids :The organic acids are among the majorcellular constituent undergoing changes during ripening.

In most of the fruits there is a considerable decrease in theacidity of fruits during ripening.

The sourness of fruits is due to the presence of organic acidslike citric, malic, succinic, tartaric, oxalic etc.

These acids usually decide the quality of fruits as theblending of sugar and acids render the fruits tasty, besides

flavour. concentration considerably changes as the fruits ripen. In fruits like oranges, the acids are converted enzymatically

into sugars rendering them sweet as they ripen, whereasthere is no change in lemons. So they remain sour till theystart decaying.

But, in some fruits like mangoes, there is a considerabledecrease in acidity when the fruits fully ripen. This isprobably due to the utilization of these acids in respirationthrough Krebs Cycle.

Generally, in fruits the total acidity shows a decrease withthe increase in ripeness of the fruits.


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Amino Acids and Proteins : The nitrogen contentof fruit is due to proteins forming insolublefraction and the soluble fraction comprised ofamino acids.

The total nitrogen content of fruits at the earlystages is high, but with the advancement ingrowth, shows gradual decrease.

This is probably due to the increase in other

constituents like water, starch, sugar, organic acidsetc.

During ripening, the total nitrogen may show afurther decrease in some cases.


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Lipids : Phospholipids occur in the cytoplasmand in many structural units of plant tissues.

They are physiologically more important than

neutral lipids in storage organs. Considerable increases in the level of total

lipids and fatty acids have been observed inripening mango in contrast to many fruits and

vegetables. However in fatty fruits of avocado the oil

composition during maturation remains moreor less constant.


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Chlorophyll : Disappearance of green colour marks

the initiation of ripening in most of the fruits.Chlorophyll content of ripening fruit decreasesuniversally.

Carotenoids : A dramatic synthesis of carotenoidsoccur during the last step of ripening. It has been

reported that the levels of precursors of carotenebiosynthesis increases progressively during ripening.

Other Pigments : The colour imparted to raw or ripefruits and vegetables are due to presence of variouspigments.

The pigments of different tissues are the chlorophylls(green), anthocyanin [reddish to purple], flavonoids[yellow], leucoanthocyanins [colorless], tannins[colorless to yellow or brown], betalains [red],quinones and xanthones [yellowish] and carotenoids

[yellow and red].


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During storage some of these pigments undergoconsiderable changes.

Carotenoids formation and destruction may be affected

by the storage conditions. In certain instances, thesereactions are stimulated by O2, inhibited by light andhigh temperature.

Anthocyanin synthesis is stimulated by light and isoften affected by temperature.

Purple colour of red cabbage intensifies when storedbelow 10o C.

Chlorophyll degradation is accompanied by synthesisof other pigments as the fruits ripen.

Chlorophyll metabolism is markedly influenced byenvironmental parameters, such as light, temperature

and humidity and the effects of these factors arespecific for the tissues.

For example, light accelerates degradation ofchlorophyll in ripening tomatoes and promotesformation of the chlorophyll pigment in cold stored

potatoes.


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Tannins : The tannins and other polyphenolicconstituents are present in abundant quantities inimmature, raw or developing fruits.

As the maturity and ripening progresses the total

polyphenolic content reduces gradually. Pectic Substances : The most obvious changes during

ripening of fruit are the alteration in texture. The plant cell wall is made up of cellulose fibrils

embedded in a matrix consisting largely of pecticsubstances, hemicellulose, proteins, lignins etc andwater.

Cell wall and middle lamella components increaseduring development of fruits, but as the fruit ripens thecontent of soluble pectates and pectinates increase,while total pectic substances decrease.


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The cell walls are surrounded by parenchymatouscells, which will absorb water and generatehydrostatic pressure within the living cells. This iscalled turgor pressure that gives the desirable

property of crispness to the commodity. During storage, the loss of moisture due to

transpiration and respiration results in the loss ofcrispness or the turgidity of the commodity.

During ripening, the protopectin, which isinsoluble decreases in quantity and the solublepectin content rises, thereby making the flesh lessfirm or soft.


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Volatile Products: Each fruit has specific aromawhich ripened fruit emanates.

Although different fruits vary in nature of volatile

compounds, they are emitted in noticeable amountonly when the fruit starts ripening.

Although the degree of maturity is the mainphysiological factor affecting aroma production,

the aroma composition is also affected byenvironmental conditions during maturation.

In overripe fruits mostly alcohol and esters areformed when fermentation develops.


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One of the marked differences between an unripeand ripe fruit is the intensity of flavour of the fruit.

The flavour of fruits or vegetables are considered

to originate by the presence of basic constituents Besides ethylene, a number of other volatile

odorous constituents like amyl esters of formic,acetic, valeric and caprylic acids are present.

These organic emanations produced duringripening of fruits contribute to the aroma of fruitsand hence are of considerable importance from thestandpoint of fruit quality.


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Enzymes : Enzyme action is responsible for manychemical and physical effects during ripening.

Softening of fruits, conversion of starch to sugar orvice versa, changes in amino acid content, and

enzymes bring changes in color. The change from starch to sugar, sucrose to invert

sugar or protopectin to pectinic acid are all due toenzymic reactions.

Oxidative enzymes like catalase and peroxidase

were shown to have increased to a considerableextent in Alphonso and Neelam varieties ofmangoes during ripening as indicated by thehigher rate of respiration

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Fruit and Vegetable Technology