H1: Importance of fruits and vegetables
Classification of horticultural products
Different classification systems possible
- Botanical: scientifically correct but not very useful as whole plants / any of separate organs
may have vastly different characteristics
- According to storage requirements: used in practice but does not provide any insight
- According to use, eg fruit, vegetable, florist item, agricultural seed product …: not very useful
bc some products have different uses
- According to plant part & stage of development: allows understanding of nature of harvested
product & predict behaviour after harvest
Intact plants
- Retain shoot & root system
- Little / no harvest injury & max capacity to continue / recommence growth & development
- Typical examples:
o Herbs
o Strawberry / raspberry plants
▪ Plants harvested in December
▪ Stored in freezer at -1°C until eg August, harvest in October
▪ Low sugar content, expensive production (heating of greenhouse)
o Leek
o Sprouts
Aboveground detached plant parts
Leaves
- Leaf blade (thin flattened portion) & petiole
- Function
o Photosynthesis
o Transpiration (temp control, large surface to volume ratio), reduced after harvest by
closure of stomata
o No long term carbon storage → poor storage potential
- Often covered with relatively thick waxy cuticle
- Eg baby leaf
Petioles
- Duct for transport of photosynthate from & water / mineral transport to leaf blade
- Long (eg celery) / short (many Brassica sp)
Stems and shoots
- Products used exclusively for stem tissue: asparagus, sugar cane
- Often meristematic, metabolically very active
- Can take up water & continue growing
- Often geotropic response
1
,Flowers
- Compressed shoots made up of specialised foliar parts adapted for reproduction
- Young, diverse, metabolically active tissue
- Little stored carbon
- Relative short period from anthesis / flower opening to seed maturation → highly perishable
- Attached leaves & stems often strongly influence postharvest behaviour
- Often no photosynthesis possible
- Borne on stem / flower stalk
- Many different structures
Fruit
- Matured ovary plus associated parts
- Many vegetables are actually fruits (eg tomato, cucumber, peas)
- Dried fruit
o Fruit wall dry & sclerenchymatous at maturity; eg wheat, rice …
o Not covered in this course
- Fleshy fruit
o Morphology widely variable
o Fleshy portion derived from pistil / from accessory parts
o Ovary wall becomes pericarp
▪ Exocarp: skin; contains oil glands, pigments
▪ Mesocarp: often part which is consumed
▪ Endocarp: inside layer of pericarp directly surrounding seeds
o Edible parts variable
▪ Apple (Malus x domestica Borkh): accessory tissue (base of sepals & petals)
▪ Strawberry (Fragaria x ananassa, Duchesne): receptable tissue
▪ Peach (Prunus persica, (L.) Batsch): mesocarp
- Subclasses
o Berry: pulpy fruit from single ovary that develop several to many seeds; eg tomato
(Lycopersicon esculentum Mill.), banana (Musa acuminata L.)
o Hesperidium: modified berry with leathery rind with inner pulp juice sacs / vesicles;
eg orange (Cirtus sinensis (L.) Osbeck)
o Pepo: modified berry with modified hard outer rind; eg cucumber (Cucumis sativus,
L.)
o Drupe: simple fruit derived from single carpel where mesocarp tissue becomes thick
& fleshy; eg peach
o Pome: simple fruit comprised of several carpels, edible portion is made up of
accessory tissue; eg apple
- Strawberry: achenes are actual fruit (simple thin-walled dried fruit containing 1 seed & with
free seed coat, attached to pericarp at only 1 point)
- Handling & storage requirements do not follow same classification
- Better classification for postharvest technology purposes
o Climacteric fruits: have potential to ripen after harvest
o Non-climacteric fruit: does not ripen after harvest
Mushrooms
- Members of Ascomycetes & Basidiomycetes
- Sometimes above-ground, sometimes below-ground (truffles)
- Reproduce from spores
- Part of interest: fruiting body
- Continuous development after harvest (opening of cap)
2
,Belowground detached plant parts
Roots
- Modified to form storage organs in several crops
- Swollen structures that may contain reserves, primarily of starch & sugars
- Examples
o Radish
▪ Partly root, partly hypocotyl
▪ Secondary xylem continues to grow & divide
▪ Mainly cellulose & water
o Carrot
▪ Formed from hypocotyl & taproot tissue
▪ Massive development of parenchyma in which starch is stored
- Often protective periderm
o Often in wound healing
o Exposed cells are first sealed with suberin & other fatty materials
o High RH, proper temp & adequate aeration necessary for sealing of wound
Rhizomes and tubers
- Underground structure but anatomically stems
- Arise from lateral buds near base of main stem
- Grow predominantly horizontally through soil
- Have nodes & internodes with leaves
- Buds (eyes) form in axils of leaves & may elongate into shoots & adventitious roots
- Rhizomes: entire stem = enlarged & below soil (eg ginger (Zingiber officinale Rocoes)
- Tubers, eg potato (Solanum tuberosum L.), yams
o Form as swelling at end of short rhizomes
o Retain capacity to form periderm after harvest
Bulbs
- Underground buds in which stem is reduced to plate with very short internodes
- Sheating leaf bases swollen to form storage organ
- No anatomical distinction between above-ground parts & below-ground parts → no
formation of protective layer such as in abscission zones / periderms, curing of neck & outer
leaf bases needed
- Have dormant period during which metabolic rate = low, if dormancy is broken & suitable
environment conditions exist growth = possible
- Eg onion (Allium cepa L.)
Corms
- Short, vertical, swollen underground plant stem
- Similar to tuber but with base plate from where roots grow & tunic
- Serves as storage organ used by some plants to survive winter / other adverse conditions
such as summer drought & heat
- Terminal bud grows into new plant
- Eg Taro (Colocasia esculenta (L.) Schott)
3
, Fruit and vegetable products
- Fresh fruit & vegetables
o Sold in bulk, trays / individual
o Often commercialisation by farmers (developing countries), co-operatives (eg
Belgium), commercial storage facilities / packing houses
- Minimally processed
o Washed, cut / shredded, packaged
o Highly perishable
o Refrigeration / modified atmosphere packaging needed
o Eg fruit salads, shredded lettuce, soup vegetables
o Convenience = driving factor
- Beverages
o Juices
▪ Obtained by mechanical procedures
▪ Colour, taste, aroma of original fruit
▪ Sometimes sugar addition & vitamin enrichment allowed
o Nectar: sieved juices / diluted with sugar syrup
o Soft drinks
o Wine
- Jams & jellies
o Early effort to preserve fruit
o Essentially formation of pectin-sugar-acid gel
- Frozen fruit & vegetables
o Freezing & storage at -18°C
o Taste, aroma, texture altered to some extent
o No inactivation of microorganism, only retardation
o Enzymes remain active → often mild thermal treatment (blanching) required
- Canned fruit & vegetables
o Pasteurisation (acid fruit) / sterilisation by heat treatment
o Taste, aroma, texture altered to some extent
o Shelf-stable fruit
- Dried fruit & vegetables
o Very old
o Commercialised as such (eg dried apricots) / as ingredient (eg dried vegetables in
soup, fruit powders in Asian dinners)
o New product with taste & aroma somewhat related to original product, texture
completely different
- Fermented fruit & vegetables & related products
o Pickled vegetables: soaked in brine, production of lactic acid
o Chutney (India): fresh, chopped primarily vegetable / fruit with added seasoning, dry
/ wet, often containing green chili peppers
o Salsa (Mexico)
4
Classification of horticultural products
Different classification systems possible
- Botanical: scientifically correct but not very useful as whole plants / any of separate organs
may have vastly different characteristics
- According to storage requirements: used in practice but does not provide any insight
- According to use, eg fruit, vegetable, florist item, agricultural seed product …: not very useful
bc some products have different uses
- According to plant part & stage of development: allows understanding of nature of harvested
product & predict behaviour after harvest
Intact plants
- Retain shoot & root system
- Little / no harvest injury & max capacity to continue / recommence growth & development
- Typical examples:
o Herbs
o Strawberry / raspberry plants
▪ Plants harvested in December
▪ Stored in freezer at -1°C until eg August, harvest in October
▪ Low sugar content, expensive production (heating of greenhouse)
o Leek
o Sprouts
Aboveground detached plant parts
Leaves
- Leaf blade (thin flattened portion) & petiole
- Function
o Photosynthesis
o Transpiration (temp control, large surface to volume ratio), reduced after harvest by
closure of stomata
o No long term carbon storage → poor storage potential
- Often covered with relatively thick waxy cuticle
- Eg baby leaf
Petioles
- Duct for transport of photosynthate from & water / mineral transport to leaf blade
- Long (eg celery) / short (many Brassica sp)
Stems and shoots
- Products used exclusively for stem tissue: asparagus, sugar cane
- Often meristematic, metabolically very active
- Can take up water & continue growing
- Often geotropic response
1
,Flowers
- Compressed shoots made up of specialised foliar parts adapted for reproduction
- Young, diverse, metabolically active tissue
- Little stored carbon
- Relative short period from anthesis / flower opening to seed maturation → highly perishable
- Attached leaves & stems often strongly influence postharvest behaviour
- Often no photosynthesis possible
- Borne on stem / flower stalk
- Many different structures
Fruit
- Matured ovary plus associated parts
- Many vegetables are actually fruits (eg tomato, cucumber, peas)
- Dried fruit
o Fruit wall dry & sclerenchymatous at maturity; eg wheat, rice …
o Not covered in this course
- Fleshy fruit
o Morphology widely variable
o Fleshy portion derived from pistil / from accessory parts
o Ovary wall becomes pericarp
▪ Exocarp: skin; contains oil glands, pigments
▪ Mesocarp: often part which is consumed
▪ Endocarp: inside layer of pericarp directly surrounding seeds
o Edible parts variable
▪ Apple (Malus x domestica Borkh): accessory tissue (base of sepals & petals)
▪ Strawberry (Fragaria x ananassa, Duchesne): receptable tissue
▪ Peach (Prunus persica, (L.) Batsch): mesocarp
- Subclasses
o Berry: pulpy fruit from single ovary that develop several to many seeds; eg tomato
(Lycopersicon esculentum Mill.), banana (Musa acuminata L.)
o Hesperidium: modified berry with leathery rind with inner pulp juice sacs / vesicles;
eg orange (Cirtus sinensis (L.) Osbeck)
o Pepo: modified berry with modified hard outer rind; eg cucumber (Cucumis sativus,
L.)
o Drupe: simple fruit derived from single carpel where mesocarp tissue becomes thick
& fleshy; eg peach
o Pome: simple fruit comprised of several carpels, edible portion is made up of
accessory tissue; eg apple
- Strawberry: achenes are actual fruit (simple thin-walled dried fruit containing 1 seed & with
free seed coat, attached to pericarp at only 1 point)
- Handling & storage requirements do not follow same classification
- Better classification for postharvest technology purposes
o Climacteric fruits: have potential to ripen after harvest
o Non-climacteric fruit: does not ripen after harvest
Mushrooms
- Members of Ascomycetes & Basidiomycetes
- Sometimes above-ground, sometimes below-ground (truffles)
- Reproduce from spores
- Part of interest: fruiting body
- Continuous development after harvest (opening of cap)
2
,Belowground detached plant parts
Roots
- Modified to form storage organs in several crops
- Swollen structures that may contain reserves, primarily of starch & sugars
- Examples
o Radish
▪ Partly root, partly hypocotyl
▪ Secondary xylem continues to grow & divide
▪ Mainly cellulose & water
o Carrot
▪ Formed from hypocotyl & taproot tissue
▪ Massive development of parenchyma in which starch is stored
- Often protective periderm
o Often in wound healing
o Exposed cells are first sealed with suberin & other fatty materials
o High RH, proper temp & adequate aeration necessary for sealing of wound
Rhizomes and tubers
- Underground structure but anatomically stems
- Arise from lateral buds near base of main stem
- Grow predominantly horizontally through soil
- Have nodes & internodes with leaves
- Buds (eyes) form in axils of leaves & may elongate into shoots & adventitious roots
- Rhizomes: entire stem = enlarged & below soil (eg ginger (Zingiber officinale Rocoes)
- Tubers, eg potato (Solanum tuberosum L.), yams
o Form as swelling at end of short rhizomes
o Retain capacity to form periderm after harvest
Bulbs
- Underground buds in which stem is reduced to plate with very short internodes
- Sheating leaf bases swollen to form storage organ
- No anatomical distinction between above-ground parts & below-ground parts → no
formation of protective layer such as in abscission zones / periderms, curing of neck & outer
leaf bases needed
- Have dormant period during which metabolic rate = low, if dormancy is broken & suitable
environment conditions exist growth = possible
- Eg onion (Allium cepa L.)
Corms
- Short, vertical, swollen underground plant stem
- Similar to tuber but with base plate from where roots grow & tunic
- Serves as storage organ used by some plants to survive winter / other adverse conditions
such as summer drought & heat
- Terminal bud grows into new plant
- Eg Taro (Colocasia esculenta (L.) Schott)
3
, Fruit and vegetable products
- Fresh fruit & vegetables
o Sold in bulk, trays / individual
o Often commercialisation by farmers (developing countries), co-operatives (eg
Belgium), commercial storage facilities / packing houses
- Minimally processed
o Washed, cut / shredded, packaged
o Highly perishable
o Refrigeration / modified atmosphere packaging needed
o Eg fruit salads, shredded lettuce, soup vegetables
o Convenience = driving factor
- Beverages
o Juices
▪ Obtained by mechanical procedures
▪ Colour, taste, aroma of original fruit
▪ Sometimes sugar addition & vitamin enrichment allowed
o Nectar: sieved juices / diluted with sugar syrup
o Soft drinks
o Wine
- Jams & jellies
o Early effort to preserve fruit
o Essentially formation of pectin-sugar-acid gel
- Frozen fruit & vegetables
o Freezing & storage at -18°C
o Taste, aroma, texture altered to some extent
o No inactivation of microorganism, only retardation
o Enzymes remain active → often mild thermal treatment (blanching) required
- Canned fruit & vegetables
o Pasteurisation (acid fruit) / sterilisation by heat treatment
o Taste, aroma, texture altered to some extent
o Shelf-stable fruit
- Dried fruit & vegetables
o Very old
o Commercialised as such (eg dried apricots) / as ingredient (eg dried vegetables in
soup, fruit powders in Asian dinners)
o New product with taste & aroma somewhat related to original product, texture
completely different
- Fermented fruit & vegetables & related products
o Pickled vegetables: soaked in brine, production of lactic acid
o Chutney (India): fresh, chopped primarily vegetable / fruit with added seasoning, dry
/ wet, often containing green chili peppers
o Salsa (Mexico)
4
