Raspberries are widely grown berry fruits in the Pacific Northwest of America. Oregon and Washington in the USA, and southwestern British Columbia in Canada, are the primary regions in North America for raspberry production.  Raspberry can be divided to red raspberry and black raspberry, but 97% of the raspberries grown in Oregon and Washington are the red variety, and the majority of them are processed into a variety of food products. Many different varieties of red raspberry are grown in this region, with the most popular cultivars are ‘Meeker’, ‘Willamette’ and ‘Tulameen’.  GC/Olafctometry studies have identified raspberry ketone, Zingerone, α-ionone, β-ionone, linalool, (Z)-3-hexenol, geraniol, nerol, α-terpineol, Furaneol, hexanal, β-ocimene, 1-octanol, β-pinene, β-damascenone, ethyl 2-methylpropanoate, (E)-2-hexenal, heptanal and benzaldehyde as key aroma-active compounds contributing to raspberry aroma.  Chiral distribution analysis demonstrates a much higher percentage of one isomer over another, particularly α- ionone, α-pinene, and the delta-lactones. More than 96% of the isomeric form of α- ionone are (R)- form, and more than 96% of δ-octalactone and δ-decalactone lactone are the (S)-isomer. Linalool is nearly a racemic mixture, with a slightly higher percentage of the (S)- isomer.  Terpinen-4-ol is a 20/80 mixture favoring the (S)-isomer. Little variation is seen among ‘Meeker’ grown at different locations for the isomeric compounds, however, there are considerably variations between ‘Meeker’ and the other cultivars.  The largest variations between cultivars are seen for linalool and 6-methyl-5-hepten-2-ol.  Linalool shows a more racemic mixture for non-‘Meeker’ cultivars, particularly ‘Tulameen’ and ‘Willamette’.  6-Methyl-5-hepten-2-ol has more than 94% of the (R)-isomer for ‘Meeker’ cultivar, while the percentage of (R)-isomer was much lower for non-‘Meeker’ cultivars, particularly ‘Willamette’.  Overall ‘Chilliwack’ red raspberries show the most variation from ‘Meeker’ for aroma compounds, ‘Yellow Meeker’ golden raspberries show the least difference from red “Meeker” for volatile compounds.

Chiral aroma-active compounds in red raspberries

2019 Spring National Meeting

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