Aromas

Aromas from fruit...

The fresh or “green” taste of fruit juices is produced by the presence of compounds which have low boiling points and are therefore volatile. They evaporate into the air (and up your nose) as soon as the skin of the fruit is broken. During the processing of concentrated juice the volatiles or aromas are recovered at an early stage in order to be returned later to give balance to the concentrated juice.

Many esters, aldehydes and alcohols are common to a variety of fruits. For this reason it is possible to detect “blackcurrant”, “gooseberry”, “blackberry” notes in wine, which after all, has been made purely from grapes. In the case of citrus juices much of the aromatic nature comes from the peel: oil soluble aromatic compounds are stored in oily glands.

Since it has an aroma or essence this type of oil is known as an essential oil with perhaps the most important component for orange juice being the terpineols.

VOLATILES OF APPLE JUICE
Component Typical ppb in juice
ESTERS RANGE
Ethyl 2-methyl butyrate 30 - 50
Ethyl butyrate 250 - 400
Isopentyl acetate 40 - 60
Hexyl acetate 150 - 350
Hexyl 2-methyl butyrate 30 - 50
ALDEHYDES  
trans-2-Hexenal 1,400 - 1,600
Hexanal 1,400 - 1,600
Benzaldehyde 90 - 110
ALCOHOLS  
Ethanol 25,000 - 40,000
Butanol 13,000 - 15,000
Isoamyl alcohol 1,400 - 1,600
Hexanol 2,500 - 4,000
trans-2-Hexenol 200 - 400

The term “fold” indicates the weight of fruit needed to produce one unit of aroma, eg. 150 Kg of apples would be needed to produce 1 Kg of 150 Fold Apple Aroma or 2000 Kg of peaches would be needed to produce 1 Kg of 2000 Fold Peach Aroma.

FRUIT FLAVOUR ELEMENTS
Orange Acetaldehyde, sinensal, nootkatone
Grapefruit Nootkatone, naringin
Lemon Citral, linalyl acetate, geranyl acetate
Lime Citral, limonene, coumarins
Tangerine Methyl N-methyl anthranilate, thymol
Aromas