Lecture 5: Fruits & Vegetables Flashcards
What does it mean to say “plants are autotrophs”?
- Self-nourished
- Fix carbon
- Make their own energy through photosynthesis
What does it mean to say “animals and fungi are heterotrophs”?
- “Other-nourished”
- Need to get eat carbon b/c they can’t fix it themselves like autotrophs can
How do plants carry out photosynthesis?
-Plants have green pigments called chlorophyll in their chloroplasts
-Chlorophyll captures energy from sunlight and converts it into glucose and oxygen
(CO2 + H2O + light –> glucose + O2)
Glucose cycle
Basically, after photosynthesis has occurred in plants, we consume their fruit (contains glucose) while expelling energy (ATP) and carbon dioxide
Cultivation
Planting, tending, improving, harvesting of crops/plants for human consumption and pleasure
- collecting seeds
- preparing the ground
- watering
- pruning
What are the dictionary, botanical, and culinary definitions of fruit?
- Dictionary = edible product of plant or tree, consisting of seed and its envelope (juicy, pulpy)
- Botanical = portions of a plant that house seeds (ovaries)
- Culinary = generally eaten alone or as a dessert
Pericarp
- Outer wrapping around seed
- Composed of endocarp, mesocarp, exocarp
- Can characterize fruits based on their pericarp (thick or thin components)
Fleshy fruits
All or most of the pericarp (ovary wall) is soft or fleshy at maturity
-berries, hesperidium, pepo, drupes, pomes
Dry fruits
Pericarp splits open along definite seams
-legumes, nuts
Berries
- Entire pericarp is fleshy
- May be one or many seeds
- Tomato, grape, blueberry, avocado
Hesperidium
- Berries with a leathery rind and parchment-like partitions between sections (endocarp)
- Citrus (orange, lemons, limes)
Pepo
- Berry with a hard, thick rind (exocarp) and fleshy mesocarp
- Pumpkin, cucumber, squash
Drupes
- Thin exocarp that’s flexible or dry and almost leathery
- Fleshy mesocarp with hard inner layer surrounding the seed
- Has one seed
- Endocarp = stone
- Apricot, cherries, peaches, mango, pistachios
Coconut as an example of a dry drupe
- Waterproof exocarp
- Thick, buoyant, fibrous husk (mesocarp)
- Hard, woody endocarp that surrounds seed
- Seed embryo is embedded in the coconut meat (endosperm)
- Coconut milk = liquid endosperm
Nuts
- A dry fruit with one large seed and a very hard pericarp
- Drupes in which we eat the seed inside the pit instead of the fruit
- Walnuts, chestnuts, hazelnuts
Pomes
- Fruits that have several small seeds
- Seeds surrounded by core (pericarp)
- Core surrounded by thick, edible hypanthium layer
- Apples, pears
Legumes
- A dry fruit with a pericarp that splits open along a seam
- Beans, soy beans, peanuts
Vegetable
- Generally eaten with the main course of a meal
- Classified according to the part of the plant from which it is derived (leaf, stem, root, flowering, bulbs)
- Botanical fruits such as cucumbers, squash, pumpkins, and legumes such as green beans and peas are also considered veggies from a culinary standpoint
Name the main quality attributes of fruits and veggies?
- Nutrition
- Color
- Taste
- Texture
Nutrition as a quality attribute for fruits and veggies
- Macronutrients (carbs, lipids, proteins)
- Fiber
- Micronutrients (vitamins, minerals)
USDA guidelines for fruits and veggies
- USDA recommends 2.5 cups of fruits and veggies per day
- Recommends to eat a variety (different colors)
Difference between variety and cultivar?
- Variety = appearance distinct from other varieties, but will hybridize freely with other varieties (bell pepper, jalapeño pepper)
- Cultivar = aka cultivated variety distinct from other cultivars, and must be possible to propagate (Excaliber bell pepper, Cal Wonder bell pepper)
Significance of cultivars
- Varieties cultivated for a specific purpose
- Some have higher levels of certain nutrients than others
- Cultivars nowadays focus on disease resistance, shelf life, appearance, and taste
Color as a quality attribute for fruits and veggies
- Acceptability of a food is often based solely on its color
- Different colors provide different phytonutrients
- Colors are the result of different pigment molecules each with different biological activity
Name the classes of pigments found in plants
- Lipid soluble (chlorophylls, carotenoids)
- Water soluble (anthocyanins, betalins)
Chlorophylls
- Fat soluble, green pigment with Mg atom bound to center
- During heating, the Mg gets replaced by H+ ions and turns an olive color
- If Mg is replaced by copper ions then it turns bright green
Carotenoids
Family of fat-soluble plant pigments that give yellow, orange and red colors to tomatoes, watermelon, pink grapefruit, apricots, bell peppers, egg yolk, milk fat, etc.
Lycopene
- Red pigment
- Main pigment in tomatoes and watermelon
- Thought to be protective in prostate cancer
Beta carotene
- Found in most greens as well as carrots (orange pigment)
- Vitamin A pre-cursor
- Often added to foods as a colorant, a vitamin A source or as an antioxidant to keep foods from going rancid
Anthocyanins
- Water soluble pigments located in the vacuole
- Give red, purple, and blue colors to berries, red grapes, apples, red cabbage, radishes, eggplant
- Change their color with pH
Betalains
- Found primarily in red beet root
- Can produce beeturia (pink/red urine due to the excretion of beet pigment after eating beets)
Taste as a quality attribute for fruits and veggies
-Taste = chemical sense perceived by specialized receptor cells that make up taste buds (sweet, salty, bitter, umami, sour)
Flavor
- Flavor = fusion of multiple senses (taste, aroma, irritation, etc.)
- To perceive flavor, the brain interprets gustatory (taste) stimuli and olfactory (smell) stimuli
Texture as a quality attribute of fruits and veggies
Depends upon:
- Turgor = rigidity of plant cells resulting from being filled with water
- Freezing can cause damage to cell membranes
- Thickness of cell wall
- Pectin (gels) and starch
Controlled atmosphere storage
- Storage method in which oxygen, carbon dioxide, and nitrogen concentrations are regulated
- Lengthens storage life by retarding ripening and decay, preventing disorders, and maintaining texture
Optimum storage conditions for fruits and veggies
- Low temp
- Low oxygen
- High relative humidity
- High carbon dioxide
- Low light
