L15 organic acids

Question 1

Organic Acids (OA)

Answer 1

Important in all plants:
•Photosynthesis in CAM and C4 plants
•Energy production
•Carbon storage
•Stomatal conductance
•Biosynthesis of amino acids
•Plant - microbe interactions
•Mechanisms allowing plants to dal with excess cations
•Changing osmotic conditions and soils low in nutrients as well as with high 
metal content3

Question 2

Organinc acids or Titratable acidity (TA)

Answer 2

Important for taste
•responsible for sourness and contributing to the flavor

One of the main ripening indices
•Determines the harvest date of fruits
•Titratable acidity (TA):
Study the factors that influence concentration in plants and fruit cells

The processes involved in the metabolism and accumulation of organic acids in mesocarp cells are under both genetic and
environmental control
•Preharvest
•Postharvest

Question 3

Titratable acidity

Answer 3

Although titratable acidity does not measure all acids, TA is generally considered a better way to measure perceivable acidity than pH

*its closer to taste than pH

Question 4

Importan organic acids in F&V

Answer 4

• malic acid & citric acid responsible to acidity
• ascorbic acids (vit C) and chlorogenic acids (CGAs)

Patterns of organic acid accumulation
-not depending on the fact that fruits are climacteric or not, or on respiration
-Some climacteric fruit utilizes malate for respiratory burst (plum, tomato) others
increase malate during ripening (banana)

Question 5

Concentration changes during ripening – Stored OA are metabolized

Answer 5

1. Total amount p fruit as well as p g FW (grape, tomato)
2. Only decrease p g FW; total amount p fruit is increasing, the increase in size of the fruit causes a dilution effect (strawberry, mango)
3. Increase of OA concentration, and content per fruit increases throughout ripening
   (lemon)

*depending on the fruit there is either dissimilation or synthesis of stored citric acid cycle acids

Question 6

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