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SOKOINE UNIVERSITY OF AGRICULTURE
DEPARTMENT OF FOOD TECHNOLOGY, NUTRITION & CONSUMER SCIENCE
COURSE PROGRAM: BSc. FOOD SCIENCE AND TECHNOLOGY
FT 212: FOOD HANDLING, STORAGE AND
PROTECTION
ASSIGNMENT NO 2:
POST_HARVEST LOSSES IN ROOTS AND TUBERS
CARROTS
PREPARED BY
PILYSON, VISITANTULY G
FST/E/2017/0001
INSTRUCTOR: DR. RASHID SULEIMAN(PhD)

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ABSTRACT
This paper is specifically intended to explain the post-harvest losses encountered in root and
tubers specifically carrots Daucus carota. The root vegetable that is highly perishable,
susceptible to microbial invasion, enzymatic activities resulting in rotten products soon after
harvest. Physical disintegration, mechanical bruising and physical damage that are primary
physical losses and are essential for secondary attacks by microorganisms in carrots.
A good source of provitamins such as beta-carotene, the one easily converted to vitamin A by
the body and antioxidant action are characteristics of carrots.

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INTRODUCTION
Post-harvest losses in the food production system can be defined as the losses of food that can
occur after harvest and the moment of human consumption. They include losses such as when
grains are threshed, winnowed, and dried, as well as losses along the chain during
transportation, storage, and processing. Also, the loss can occur when the grain is being stored
for auto-consumption or while the farmer awaits a selling opportunity or a rise in prices.
ROOTS AND TUBERS are plants yielding starchy roots, tubers, rhizomes, corms and stems.
They are used mainly for human food (as such or in the processed form), for animal feed and
for manufacturing starch, alcohol and fermented beverages including beer. (FAO, 1994)
As the definition of root and tuber support, carrots are one of the root vegetables.
CARROTS: Scientifically carrot is known as Daucus carota
It is a root vegetable, usually orange in colour, though purple, black, red, white, and yellow
cultivars exist. Carrots are a domesticated form of the wild carrot, Daucus carota, native to
Europe and southwestern Asia. The most commonly eaten part of the plant is the taproot,
although the stems and leaves are eaten as well. The domestic carrot has been selectively bred
for its greatly enlarged, more palatable, less woody-textured taproot.
Fast-growing cultivars mature within three months (90 days) of sowing the seed, while
slower-maturing cultivars need a month longer (120 days). The roots contain high quantities of
alpha- and beta-carotene, vitamin K and vitamin B6. Consumption of carrot has been
suggested by many researchers on the prevention of night blindness due to the presence of
Vitamin A precursors (Provitamin, Beta carotene).
COMPOSITIONS OF CARROT. Raw carrots are 88% water, 9% carbohydrates, 0.9% protein,
2.8% dietary fiber, 1% ash and 0.2% fat. Carrot dietary fibre comprises mostly cellulose, with
smaller proportions of hemicellulose, lignin and starch. Free sugars in carrot include sucrose,
glucose, and fructose.
The carrot gets its characteristic, bright orange colour from β-carotene, and lesser amounts of
α-carotene, γ-carotene, lutein, and zeaxanthin. α- and β-carotenes are partly metabolized into
vitamin A, Carrots are also a good source of vitamin K and vitamin B6.
CARROT PRODUCTION IN TANZANIA: In Tanzania carrot is one of the staples of the country
that comes with a tapered, orange taproot that is
edible and mostly used as ingredients for
different recipes. It is widely grown in Morogoro
and Tanga followed by Mbeya, Songwe,
Mwanza, Mara, Geita, Arusha, Kilimanjaro and
Iringa regions. (MMAinterviews,
November 2016).
Health Benefits of carrot includes prevention
against cancer due to presences of antioxidant
(Vitamin c), Leukemia, A 2011 study (Zaini, R., Clench, R., & Le_Maitre, L., 2011) found that
carrot juice extract could kill leukemia cells and inhibit their progression. Vision, also carrots are
essential for preventions of night blindness and help an individual to clearly see in darkness.

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POST_HARVEST LOSSES IN CARROTS
Carrot is one of the perishable root vegetables due to their high moisture contents, hence are
highly prone to excessive loss soon after harvest.
Losses in harvest can be classifield according to loss agents
They include physical agents, chemical agents, microbiological agents and pests, and
biochemical agents.
Physical agents
Soon after harvest, rough handling of carrot such as bruising, compactions in sacs for
transportations, physical desentagration of carrot resulted from mechanical forces can result in
potential physical loss of the product that essentially reduces the quality and market value as
well as increased the susceptibility of the product to microbial agents invasions and foreign
materials contamination.
Biochemical agents
There are different biochemical reactions that normally take place during the growth of the
carrot. Enzymatic activities that take place are essential for growth and metabolism at cellular
level. After harvest, these enzymatic activities continue as a result of quality losses of the
product, overripening and browning reactions (Discolouration of carrot).
➔ Phenolic browning: Phenolic browning (or surface browning) is seen as browning or
discoloration of the surface of the carrot. It can develop when carrots are washed and
stored in cool rooms for long periods before packing. Abrasion caused by mechanical
washing often removes the epidermal layer (outer skin), exposing the carrot tissue to
oxidation of phenolic compounds, which turn brown, or black in severe cases.
➔ Bitterness: A quality loss of carrots whereby carrots develop off-flavours or bitterness in
cool storage, caused by the production of compounds called isocoumarins.
Isocoumarins develop when carrots are exposed to ethylene.
Ethylene is a gas produced naturally by many fruits and vegetables, such as apples, bananas
and tomatoes, during ripening. Retailers, exporters and consumers should be aware that storing
carrots with fresh products that produce ethylene can cause bitter flavours to develop in carrots.
Store carrots in sealed plastic bags if domestic refrigerators contain ethylene producing fruit.
➔ Silvering or scaling: Carrots can sometimes develop a scaly surface in storage. The
carrot surface has a white, flaky appearance that looks similar to dandruff. This symptom
appears when carrots become dehydrated.

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Microbiological agents and Pests
These are agents that cause quality and quantitative loss to the product. Major post-harvest
losses in carrots are due to Sclerotinia rot, Botrytis rot, Bacterial soft rot (Erwinia) and Sour rot
(Geotrichum). Sclerotinia rot is the most prevalent.
➔ Fungi: The Sclerotinia fungus infects the carrot roots in the field through the crown
and during storage, the Sclerotinia fungus produces a white,
cottony mycelium which covers the roots. Infected roots are
usually soft and watery. The major sign of the disease is the
presence of white fungal growth and small black grains (sclerotes),
which look similar to mice droppings. Roots become covered with
white cottony fungal growth. Other fungi such as grey mould
(Botrytis cineria), crater rot (Rhizoctonia species) and black rot
(Alternaria radicina) have been reported to cause postharvest
losses in carrots, but these are usually prevented by using good postharvest handling
and storage.
➔ Bacteria: Bacterial soft rot, caused by the bacterium Pectobacterium carotovorum
(formerly Erwinia carotovora). Affected carrots
develop soft lesions and eventually become a
mushy and slimy mass of tissue. Stored carrots
can become affected on any part of the root and,
in severe cases, an unpleasant odour is present.
The tips of carrots are often affected.
Pests: Pests such as false wireworms, cutworms and millipedes sometimes cause problems, by
damaging the roots. Earlier harvest is sometimes justified when damage occurs late in growth.
Minimization of post_harvest losses in carrots:
❏ Pre-harvest application of a registered fungicide
❏ Minimal handling of carrot during harvest and at storage.
❏ Bitterness can be controlled by avoiding store carrots with fruit, vegetables or flowers
that produce ethylene. As this will result into quality loss of the product
❏ Processing of the product to valuable products such as dried carrots, carrot in powder
form, syrup of carrot (Carrot juice syrup) and bottled carrot.
❏ A rapid removal of field heat from freshly harvested roots.
❏ Packaging of carrot after branching increases shelf life and minimize post_harvest loss
that may be caused by mould and bacteria
contaminations. Example is by packing carrots into
plastic-lined cartons or pre-pack plastic bags as soon as
possible after harvest. Leaving carrots in bulk bins
unprotected in cool stores will lead to dehydration.
Plastic bin liners will reduce dehydration if carrots are left
for prolonged periods in bulk bins.

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❏ Increasing row width to increase ventilation since prolonged periods of leaf wetness
induce rot.
❏ Control temperature storage by using refrigirators and freezers. This will inhibit and
inactivate activity of endogenous enzymes as well as retardation growth and
multiplication of microorganism.
❏ Treatments for short term storage such as thermal processing by scalding and blanching
to inactivate enzyme prior freezing or refrigiration. Enzyme are source of deterioration in
carrots, as they cause browning reactions, discolarations and overripening of the
product.
❏ Post-harvest application of a registered antimicrobial such as Dowicide (Ophenylphenol).
❏ Wash carrots as soon as possible after harvesting to prevent phenolic compounds
browning and keep washed carrots moist.
❏ Don’t leave carrots in bulk bins in the cool room; pack them as soon as possible after
cooling to maximize quality.
❏ The use of brush polishing which removes the carrot’s outer layer (periderm) effectively
removes the possibility of silvering developing. Hence prevent the quality loss of the
carrot.
CONCLUSION
Generally, most postharvest loss in carrots can be controlled by improving handling practices
during harvest and transportation since because, poor handling results to physical damage of
the product. Damaged product is highly prone to microbial attack and mould infections as well
as deduced shelflife storage. Other essential methods are by preservations using antimicrobial
agents and storing of carrots in refrigerated spaces soon after harvest to minimize the
postharvest loss in carrot.
Modified atmospheric packages may also be used for strengthening the shelf life of the product.

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REFERENCE
Megan Ware RDN LD. (2017, December 5). "What are the health benefits of carrots?." Medical
News Today. Retrieved from https://www.medicalnewstoday.com/articles/270191.php on 26
May. 2019
Zaini, R., Clench, M. R., & Le Maitre, C. L. (2011, November). Bioactive chemicals from carrot
(Daucus carota) juice extracts for the treatment of leukemia [Abstract].Journal of Medicinal
Food, 14(11), 1303-12. Retrieved from http://www.ncbi.nlm.nih.gov/pubmed/21864090.
Pritchard, M.K., D.E. Boese, & S.R. Rimmer. 1992. Rapid cooling and field-applied fungicides
for reducing losses in stored carrots caused by cottony soft rot. Canadian Journal of Plant
Pathology 14:177-181. Retrieved from
http://www.agr.gc.ca/resources/prod/doc/pfra-arap/csidc-crdi/pdf/carrots-carottes_eng.pdf
FAO, 1994. Roots and tubers. Retrieved from
http://www.fao.org/waicent/faoinfo/economic/faodef/fdef02e.htm on 23:43PM_May 25, 2019.