Fruits and vegetables. Plant parts we eat (APK) Plant parts we eat

Transcription

1 Fruits and vegetables Plant parts we eat (APK) ee page 247, Lecture Notes. We eat Leaves Cabbage Lettuce pinach tems Asparagus Celery Plant parts we eat Bulbs Garlic nion Roots Beet Carrot Radish weet potato 1

2 Plant parts we eat Tubers Potato Flowers Broccoli Cauliflower Fruits Tomato Pepper Cucumber eeds -- beans, corn, peas, soybeans Fruit and vegetable characteristics to preserve In preparation, processing, or preservation of fruit and vegetables we want to preserve Color Flavor Texture Nutrient value Plant tissue types Dermal uter covering, usually rich in waxes and lipids (cutin). Protects and waterproofs adjacent tissue. Vascular Xylem Transports water from roots to leaves Phloem Transports food from leaves to roots for storage 2

3 Plant tissue types Ground tissue Parenchyma Most abundant Undifferentiated t d Collenchyma trength cells trings on green beans and celery clerenchyma Even stronger than collenchyma trings in green beans, grittiness in pears Parenchyma Image courtesy of Plants and ociety, Levitin and McMahon ( Parenchyma Middle lamella is fluorescent due to staining 3

4 Collenchyma Image courtesy of Plants and ociety, Levitin and McMahon ( clerenchyma Image courtesy of Plants and ociety, Levitin and McMahon ( Plant cell Vacuole Middle lamella Amyloplast Image courtesy of Beginner s guide to Molecular Biology (www. res.bbsrc.ac.uk/molbio/guide/cell.html) 4

5 Plant cell wall polymers Cellulose emicellulose Lignin Cellulose emicellulose Image courtesy of Edu/dept/chem-eng/Biotech- Environ/FUNDAMNT/hemicel. htm Non-cellulose polymers utilizing the monosaccharides shown below 5

6 Cell wall xylan Beta-1,4-linkage A cell wall xylan Lignin A polymer comprised of phenylpropane molecules such as those shown below. Provides strength and woodiness to plant materials when it occurs in large concentration. Lignin monomers Image courtesy of Environ/FUNDAMNT/lignin.html. 6

7 Proposed lignin sub-structure Image courtesy of Environ/FUNDAMNT/lignin.html. Vacuole Contains the cell sap. Basically a drop of water contained in the cell in which various substances are dissolved. Tannins ugars alts rganic acids Flavanoids Plant acids Malic acid Found in apples and many other fruits and vegetables Citric acid Main acid in citrus fruits, many berries, pineapple xalic pinach, rhubarb (especially the leaves) 7

8 illy stuff Dr. James van Meeter, speaking in 1830 to a crowd in alem, Massachusetts, about Colonel Robert Gibbon Johnson, who was going to publicly eat a tomato illy stuff "The foolish colonel will foam and froth at the mouth and double over with appendicitis. All that oxalic acid, in one dose, and you're dead. If the Wolf Peach (tomato) is too ripe and warmed by the sun, he'll be exposing himself to brain fever. hould he, by some unlikely chance, survive, I must warn him that the skin... will stick to his stomach and cause cancer." Plant acids L-tartaric Grapes Benzoic Cranberries--a natural preservative hikimic Intermediate in secondary metabolism 8

9 Plant acids m a lic a c id citric acid oxalic acid L-tartaric acid benzoic acid s h ik im ic a c id Chlorophyll Chlorophyll/pheophytin acid heat chlorophyll Mg++ pheophytin Images courtesy of NYU/ACF cientific Visualization Laboratory ( 9

10 Chlorophyll in broccoli Carotenoids These are the most stable class of pigments in fruits and vegetables Carotene--orange orange Carrots Lycopene--red Tomato Xanthophylls--yellow Corn Carotenoids vitam in A beta-carotene lycopene 10

11 Carotene in carrots Flavonoids + Basic ring structure for anthocyanin pigm ents Anthocyanin reactions flavylium or oxonium ion (red) Anhydrobase (violet) 11

12 Anthocyanin reactions +Na+ Anhydrobase (violet) -Na+ Na odium salt of the anhydrobase (blue) Anthocyanins in red cabbage Anthoxanthins in onions 12

13 Betalins (beet pigments) + N betalin N Enzymatic browning polyphenoloxidase 1/ Cell wall phenolic rtho-quinone Enzymatic browning Image courtesy of Robertson and Christiansen ( instruct/nfm425/phenolic/index.html) 13

14 Browning inhibition Remove (or reduce) enzyme activity eat Acid Remove oxygen Vacuum pack Inert gas pack (e, Ar, Carbon dioxide) Browning inhibition Remove substrate Genetic breeding program Use antioxidants Vitamin C is commonly used Physical barrier Cover with heavy syrup, as in freezing ulfur compounds -- garlic 2 tep one N (+)--allyl-l-cysteine sulfoxide (alliin) allinase water Diallyl thiosulfinate (allicin) 2 + pyruvic acid + N3 14

15 ulfur compounds -- garlic tep two 2 D iallyl thiosulfinate (allicin) diallyl disulfide (typical garlic odor) + allyl thiosulfinate ulfur compounds -- onion (+)--(pro-1-enyl)-l-cysteine sulfoxide N enzyme water propenylsulfenic p acid (lachrymatory factor) + pyruvic acid + N3 ulfur compounds -- cabbage N K sinigrin myrosinase N allyl isothiocyanate (a mustard oil) + C K4 15

16 Changes in fruits and vegetables on ripening Color Green of chlorophyll may give way to other colors Texture Goes from hard to tender-crisp to mushy. Principally a function of changes in the middle lamellar pectic substances. Changes in fruits and vegetables on ripening Flavor tarch banana sweet corn ugar Tannins decrease on ripening Acids generally decrease on ripening (except for citrus fruits) Pectic substances Protopectin Pectinic Pectic acid acid Underripe Ripe verripe Insoluble Colloidal oluble No gel Gel No gel Lots of methyl Less methyl Almost no methyl ard ptimum Mushy 16

17 Ripening To speed ripening Treat with ethylene (C 2 4 ) To slow ripening tore in modified atmosphere (low in oxygen, high in carbon dioxide) Ethylene treatment Air only Air + low concentration of ethylene Ethylene treatment Air only Air + low concentration of ethylene 17

18 Ethylene treatment Air only Air + low concentration of ethylene Controlled (modified) atmosphere storage Nitrogen 78% xygen 21% Carbon dioxide <0.04% 95% Carbon dioxide 5% xygen Controlled (modified) atmosphere storage Nitrogen 78% xygen 21% Carbon dioxide <0.04% 95% Carbon dioxide 5% xygen 18

19 Controlled (modified) atmosphere storage Nitrogen 78% xygen 21% Carbon dioxide <0.04% 95% Carbon dioxide 5% xygen Controlled (modified) atmosphere storage Nitrogen 78% xygen 21% Carbon dioxide <0.04% 95% Carbon dioxide 5% xygen Controlled (modified) atmosphere storage Nitrogen 78% xygen 21% Carbon dioxide <0.04% 95% Carbon dioxide 5% xygen 19