► COURSE # Hort-506

► COURSE TITLE: Pre and Post Harvest Technology of Horticultural Crops

► Course Teacher: Dr. Nadeem Akhtar Abbasi

► Course Objectives & Outcomes To acquaint the students with new advances in pre and post

harvest management technology of horticultural crops.To produce technical and skilled persons in the area of post

harvest technology.To educate the students about the value addition in

horticultural products.

– Let the students evaluate the gap between local prevailing conditions of fruit, flower & vegetable markets and the recommended techniques.

– On completion of this course students should be able to describe causes of pre & post harvest losses of horticultural produce.

– Students should be able to suggest possible solutions to reduce these losses in scenario of local conditions.

TheoryWeek No.

Course Description

1. Introduction & importance; Preharvest factors affecting postharvest quality

2. Factors affecting postharvest quality

3. Climacteric and non-climacteric commodities

4. Indices of fruit maturity/ripening of important horticultural plants

5. Indices of fruit maturity/ripening of important horticultural plants

6. Harvesting and curing/ripening of different fruits

7. Harvesting and curing/ripening of different fruits

8. Harvesting and curing/ripening of different vegetables

9. Harvesting and curing of different flowers

10 Packing house operations (culling, grading, washing, cleaning, coloring, waxing and packing of important fruits, vegetables and flowers)

11 Packing house operations (culling, grading, washing, cleaning, coloring, waxing and packing of important fruits, vegetables and flowers)

12 Packing materials and containers

13 Storage (Principles and types)

14 Shipment of fruits for local & foreign markets

15 Shipment of vegetables for local and foreign markets.

16 Student presentations

Practical

Week No.

Course Description

1. Determination of harvest indices

2. Determination of harvest indices

3. Practices in harvesting

4. Practices in harvesting

5. Grading

6. Grading

7. Curing techniques

8. Packing techniques

9. Packing techniques

10 Machinery and equipments used for various operations

11 Machinery and equipments used for various operations

12 Visits to the fruit market

13 Visits to the vegetable market

14 Visits to floral markets

15 packing houses visit

16 Cold storages visit

Methodology

• Lectures -Most topics will be covered by consulting most appropriate literature multimedia and over head projector are used as teaching aids. Soft copy of each lecture is made available to students after each lecture, to eliminate the need for extensive note taking in class.

• Presentations – Last week of semester is reserved for student presentations

• Text Book – Time to time handouts and copies of research articles are provided to the students. Printed and electronic materials will be made available throughout the semester, and will form the body of course content.

• EVALUATION– Mid and Final Exams –The students will be evaluated by

conducting mid and final exams as per the schedule of the examination branch, UAAR.

– Assignment - The class will be divided into different groups, each comprising of 2-3 students. Each group will identify an issue that is relevant to the course content. More details regarding the assignment will be made available during the course of study.

– Attendance Policies- only those students are allowed to sit in exams who full fill the attendance requirement as per university rules.

Books Recommended• Kalia. M. 2006, Post harvest Technology of

vegetables. Agrotech Publishing Academy. SSS Printers New Delhi.

• Bhattacharjee S. K and L.C. De. 2005, Post-Harvest Technology of Flowers and Ornamental Plants. Pointer Publishers jaipur India.

• Burg, P. S. 2004, Post harvest Physiology and Hypobaric Storage of Fresh Produce. CABI Publishing.

• Choudhry, M. L and K. V. Parsad. 2003, Value Addition in Horticulture. Delhi Agri-Horticultural Society. Division of Floriculture and Landscaping Indian Agricultural Research Institute Pusa, New Delhi-110 012.

– Kader, A. A. 2002, Post harvest Technology of Horticultural Crops. University of California. Agriculture and Natural Resources Publication 3311.

– Mitra, S.K. (1997). Post harvest Physiology and Storage of Tropical and Sub tropical Fruits. CAB International, Wallingford, U.K. Tnompson, A.K. (1996). Post-harvest Technology of Fruits and Vegetables. Blackwell Science Ltd., Oxford.

– Wills, R. B. H., T. H. Lee, D. Graham, W. B. McGlasson and E. G. Hall (1989). Post- Harvest (3rd Ed.). BSP Professional Books, Oxford.

– O’ Breen, M, B.F. Garill and R.B. Findlay (1983). Principles and Practices for harvesting of Fruits and Nuts. AVI pub Co. Inc., Westport, Connecticut.

Importance• Produce more food– More emphasis was given

• Conserve the food– Ignored and resulted in heavy losses of horticultural

products.• 5-25% in developed countries

• 20-50% in developing countries

• Depends upon– commodity– cv.– Handling conditions

• To reduce losses, producers & handlers must understand:

– Biological factors & Environmental factors involved in Deterioration

– Postharvest techniques:• To delay senescence• Maintain best possible quality• Value addition

• Preharvest Factors:– Mineral Nutrition• Peaches and nectarines under California conditions

should be between 2.6 – 3.0% leaf nitrogen.• High levels stimulate vegetative growth, delays fruit

maturity, poor red color development and inhibits ground color change from green to yellow.• High N level also resulted in high water loss from fruit

during postharvest as compared to low N content.• N deficiency leads to small fruit with poor flavor and

unproductive trees.• High levels of N result in more susceptibility to Brown rot

in stone fruits.

• High N contents increase postharvest disorders:– Gray wall or internal browning in tomatoes– Hollow stem of broccoli– Fruit spot in peppers

• Ca has been implicated in many disorders:– Bitter pit in apple– Corkspot in pear– Blackheart in celery– Blossom end rot in

tomato– Cavity spot and cracking

in carrot– Tipburn of lettuce

• Irrigation– Amount and timing of water application:• Irrigation cutoff 20 days before harvest can increase SSC in

tomatoes• Over irrigation in melons can result in low SSC and fruit

rots.• Rapid growth from irrigation following extended drought

may result in growth cracks in carrots, potatoes, tomatoes etc.• Over irrigated strawberry shortly before harvest results in

softer fruits, more susceptible to bruising and decay

– Mulching– Soil type– Cultivar and rootstock genotype:

• Taste, yield, nutrient composition, postharvest life• Proper genotype can reduce severity of decay, insect damage and

physiological disorders.– Climatic conditions:

• Temperature• Light intensity• Humidity

– GAP• Recommended cultural practices• Food safety issues

Fruits, Veg., & Ornamentals are living tissues

• Postharvest changes cannot be stopped• Can be slowed down within certain limits

• Senescence; final stage in development– Series of irreversible events leads to breakdown

and death of cells

Fresh Hort. Crops

• High in water content– Subject to desication• Wilting• Shriveling

– Mechanical injury– Susceptible to bacteria & fungi• Pathological breakdown

Postharvest factors

• Biol. Factors: deterioration• Respiration:– Stored org. mat.: carbohydrates, proteins, fats >>>

simple end products & energy– O2 used, CO2 produced– Results in:• Loss of stored food reserves• Reduced food value• Loss of flavour (sweetness)• Loss of salable dry wt.

• Respiration:

– Rate of deterioration (Perishability) proportional to resp. rate.

– Hort. Commodities calssified according to resp. rate as in Table.

Horticultural commodities classified according to respiration rates

Range at 5ºC (41ºF)Class (mg CO2/kg-hr)* Commodities

• Very Low <5 dates, dried fruits and vegetables, nuts

• Low 5-10 Apple, beet, celery, citrus fruits, cranberry, garlic, grape, honeydew melon, kiwifruit,

onion, papaya, persimmon, pineapple, pomegranate, potato (mature), pumpkin, sweet potato, watermelon, winter

squash.• Moderate 10-20 Apricot, banana, blueberry,

cabbage, cantaloupe, carrot (topped), celeriac, cherry, cucumber, fig, gooseberry,

lettuce (head), mango, nectarine, olive, peach, pear plum, potato ( immature), radish (topped), sum, mer squash, tomato

• High 20-40 Avocado, Blackberry, carrot (with tops),Blackberry carrot

(with tops) cauliflower , leek , lettuce (leaf) lima bean radish

(radish (with tops) raspberry, strawberry

• Very high 40-60 Artichoke, bean sprouts, broccolil, Brussels

sprouts, cherimoya, cut flowers, endive, green onions, kale , okra,

passion fruit , snap bean , watercress

• Extremely high >60 Asparagus, mushroom,

parsley, peas, spinach sweet corn

• Note: Vital heat (Btu/ton/24 hrs) = mg CO2/kg-hr *220 • Vital heat (Kcal / 1,000 kg/24 hrs )= mg CO2/kg-hr*61.2

• Based on resp. and C2H4 prod. Patterns during maturation and ripening: climacteric, non-climacteric

• Climacteric fruits show large increase in CO2 and C2H4 prod. Rates coincident with ripening

• Non-climacteric show no change in their generally low CO2 and C2H4 prod. Rates during ripening

Fruits classified according to respiratory behavior during ripening

Climacteric fruits non-climacteric fruits

• Apple Muskmelon Blackberry Lychee

• Apricot Nectarine Cacao Okra• Avocado Papaya Carambola Olive

Banana Passion fruitOrange Biriba Peach Cherry Pea

• Blueberry Pear Cranberry Pepper• Breadfruit Persimmon Cucumber Pineapple• Cherimoya Plantain Date Pomegra• Durian Plum Eggplant

Prickly per• Feijoa Quince Grape

Raspberry• Fig Rambutan Grapefruit

Strawberr• Guava Sapodilla Jujube

Sumer sq• Jackfruit Sapote Lemon Tamarillo• Kiwifruit Soursop Lime

Tangerine •

Mandarin• Mango Sweetsop Longan

• Mangosteen Tomato Loquat Watermelon

Ethylene Production

• Simplest org. compounds affecting phys. Processes

• Nat. prod. Of plant metabolism, produced by all tissues of higher plants and some microorganisms

• This pl. hormone regulates many aspects of:– Growth, development and senescence– Physiol. Active in trace amounts (<0.1 ppm)

Ethylene cycle

Aminoethoxyvinylglycine

Aminooxyacetic Acid

Classification of horticultural commodities according to ethylene (C2H4) production rates

Range at 20ºC (68ºF)

Class (mg C2H4/kg-hr)* Commodities____________ • Very Low less than 0.1 Artichoke, asparagus, cauliflower

cherry, citrus fruits, grape, jujube strawberry, pomegranate, leafy vegetables, root vegetables, potato,

most cut flowers

• Low 0.1-1.0 Blackberry, blueberry, casaba melon,Cranberry, cucumber, eggplant, okra,

olive, pepper (sweet and chili), persimmon, pineapple, raspberry, tamarillo, watermelon.

• Moderate 1.0-10.0 Banana, Fig, guava, honeydew melon, Lychee, mango, plantain, tomato.

High 10.0-100.0 Apple, apricot, avocado, cantaloupe, feijoa, Kiwifruit (ripe), nectarine, papaya, peach, pear, plum.

Very high More than 100.0 Cherimoya, mammee apple, passion fruit, sapote.

• No consistent relationship bet. C2H4 prod. Rates & perishability

• Exposure to C2H4 accelerates senescence

• C2H4 prod. Rates increase with:– Maturity– Physical injuries– Disease incidence– Increased temp. up to 30C– Water stress

C2H4 Prod. Decreased by:

–Storage at low temp.

–Reduced O2 levels (<8%)

–Elevated CO2 levels (>2%)

Compositional Changes• Loss of chlorophyll (green color) is desirable in fruits but not

in vegetables.

• Development of carotenoids (yellow and orange colors) is desirable in fruits such as apricots, peaches, and citrus. Red color development in tomatoes and pink grape fruit is due to a specific carotenoid (lycopene); beta carotene is provitamin A and thus is important in nutritional quality.

• Development of anthocyanins (red and blue colors) is desirable in fruits such as apples (red cultivars), cherries, strawberries, crane berries, and red-flesh oranges. These water soluble pigments are much less stable than carotenods.

• Changes in anthocyanins and other phenolic compounds may result in tissue browning which is undesirable for appearance quality. On the other hand, these constituents contribute to the total antioxidant capacity of the commodity, which is beneficial to human health.

• Carbohydrates (starch)>>sugar is undesirable in potato but + in apple

• Sugar to starch, - in peas, sweet corn but + in potatoes

• Loss in vitamin content (vit. C), nutr. Qual.

• Prod. Of flavour volatiles with rip. + eating quality

Growth & Development• Sprouting potatoes, onions, garlic, root crops• Continuous growth of asparagus spears after

harvest, elongation, curvature>> increased toughness, palatability

• Geotropic responses in cut glad., snapdragon• Seed germination inside fruits, tomatoes,

peppers, lemons

Transpiration/water loss

• Quantity loss• Appearance• Textural quality (softening, flaccidity, limpness,

loss of crispness & juiciness)• Nutritional quality

Transpiration rate, factors

• Internal (commodity) factors:– Morphological, anatomical, surface to vol. ratio,

surface injuries and mat. stage• External or environmental– Temp., RH, air movement and atmospheric

pressure

• Outer protective coverings:– Cuticle, epidermal cells, stomata, lenticels,

trichome (hairs) Cuticle:– surface waxes, cutin in wax, layer of mix. Of

cutin, wax and carbohydrate polymers

– Thickness, structure, chemical composition varies>>>commodity and dev. stage

Control

• Apply– Waxes– Other surface coatings– Wrapping with plastic filmsManipulation of environ.

High RHControlling air circulation

Physiological breakdown

• Exposure to undesirable temps.:– Freezing injury• Held at below freezing temp. of commodity• Collapse of tissues• Total loss of commodity

• Chilling injury–Tropical and subtropical–Above freezing, 5-15C–More prominent on transfer to higher

temp.–Surface and internal discoloration,

Pitting, Water soaked areas, uneven ripening or failure, off-flavour, accelerated dev. Of surface molds and decay

• Heat injury– Direct sunlight or excessive high temp.– Bleaching, surface burning, scalding, uneven ripe,

excessive softening and desiccation.

• Preharvest nutritional imbalance– Blossom end rot of tomatoes, bitter pit of

apples>> Ca def.

• Low O2 or High CO2 injury, C2H4– <1% O2– >20% CO2

Physical damage

• Surface injuries• Impact bruising• Vibration bruising– Browning (membrane

disruption>>phenolic comps. To PPO).

– These injuries are unsightly, accelerate water loss, fungal infection, stimulate CO2 & C2H4 production.

• PATHOLOGICAL BREAKDOWN

• Bacteria & fungi• Mostly after physical or

physiological breakdown except few pathogens

• Mostly fruits & veg. exhibit considerable resistance

• Onset of ripening & senes., susceptible

• Stresses: mech. Injury, chilling, sunscald

ENVIRONMENTAL FACTORS, DETERIORATION

• TEMPERATURE:– Most influential factor– For each 10C above optimum, rate of

deterioration > 2-3 folds.Table:

Effect of temperature on deterioration rate of a non-chilling-sensitive commodity

Temperature

(°F) (°C)Assumed

Q10

Relative velocity of

deterioration

Relative shelf life

Loss per

day %

32 0 - 1.0 100 1

50 10 3.0 3.0 33 3

68 20 2.5 7.5 13 8

86 30 2.0 15.0 7 14

104 40 1.5 22.5 4 25

Note: *Q10 = Rate of deterioration at temperature (T) + 10oC

Rate of deterioration at T

TEMPERATURE contd….

– Temp. also influences effect of C2H4, reduced O2 & elevated CO2.

– Spore germination & growth rate of pathogens– If stored at below 5C immediately after harvest

can reduce incidence of Rhizopus rot

TEMPERATURE contd….

• Temp. responses of chilling sensitive & nonchilling sensitive hort. Crops

• Table:

Fruits & Vegetables classified according to sensitivity to chilling injury

CHILLING INJURY SYMPTOMS

failure of fruits to ripen increased susceptibility to

decay

CHILLING INJURY SYMPTOMS

peel and pulp discoloration

pitting loss of aroma and flavor

Fruits and vegetable classified according to sensitivity to chilling injury Group I Group II

Fruits Vegetable Fruits Vegetable

Apple Artichoke Avocado Beans, snap

Apricot Beans, lima Banana Cassava

Blackberry Beet Citrus Cucumber

Blueberry Broccoli Cranberry Eggplant

Cherry Brussels sprouts Durian Ginger

Currant Cabbage Guava Muskmelon

Date Carrot Jackfruit Okra

Fig Cauliflower Lychee Peppers

Grape Celery Mango Potato

Kiwifruit Corn, sweet Mangosteen Pumpkin

Loquat Garlic Olive Squash

Nectarine Lettuce Papaya Sweet potato

Peach Mushrooms Passion fruit Taro

Persimmons Onion Pineapple Tomato

Plum Peas Pomegranate Watermelon

Prune Radish Prickly pear Yam

Raspberry Spinach Rambutan -

Strawberry Turnip Tamarillo -

RELATIVE HUMIDITY

• Rate of water loss : vapor pressure deficit between commodity and surrounding ambient air temp. which is influenced by temp. & RH.

• At a given RH water loss increases with temp.

ATMOSPHERIC COMPOSITION

• Reduction of O2 & elevation of CO2• Intentional (modified or CA storage)• Unintentional (restricted vent. In container)• Can delay or accelerate deterioration• Depends:– Commodity, cv., physiological age, O2 & CO2 levels,

temp. & duration.

ETHYLENE

• Effect can be desirable or undesirable:• Can promote faster & uniform ripening• Exposure of nonfruit vegs. & ornamentals to

C2H4 is detrimental to quality.

LIGHT

• Greening in potatoes:–formation of chlorophyl & solanine

(toxic to humans).

OTHER FACTORS

• Chemicals:– Fungicides, growth regulators can affect

biological deterioration factors.

Definitions• Development – The series of process from the initiation of growth to death of

a plant or plant part.• Growth – The irreversible increase in physical attributes of a developing

plant or plant part.• Maturation – The stage of development leading to the attainment of

physiological or horticultural maturity• Horticulture Maturity – The stage of development when a plant or plant part

possesses the prerequisites for utilization by consumers for a particular purpose.

• Physiological Maturity – The stage of development when a plant or plant part will

continue ontogeny even if detached • Ripening – The composite of the processes that occur from the later

stage of growth and development through the early stage of senescence and that result in characteristic esthetic and food quality, as evidenced by change in composition, color, texture, or other sensory attributes.

• Senescence – Those processes that follow physiological maturity or

horticultural maturity and lead to death of tissue • Aging – Any increment of time which may or may not be

accompanied by physiological change.

Indices of Maturity

►Measurements that can be used to determine maturity of the commodity

Trade Regulation •Regulations published by legally authorities

•Minimum & maximum maturity acceptable for a given commodity Marketing Strategy

•Price incentive for the earliest or latest shipments of any commodity

•Grower take advantage of premium price