The occurrence of sugar alcohols in marine algae: Sorbitol

Sorbitol, Rubus fruit, and misconception

It is unclear how the misunderstanding that Rubus fruits (e.g., blackberries, raspberries) are high in sugar alcohol began, or when it started circulating in the United States. In reality, they contain little sugar alcohol. Numerous research groups have reported zero detectable amounts of sugar alcohol in fully ripe Rubus fruit, with the exception of three out of 82 Rubus fruit samples (cloudberry 0.01 g/100 g, red raspberry 0.03 g/100 g, and blackberry 4.8 g/100 g(∗); (∗)highly unusual as 73 other blackberry samples contained no detectable sorbitol). Past findings on simple carbohydrate composition of Rubus fruit, other commonly consumed Rosaceae fruit, and additional fruits (24 genera and species) are summarised. We are hopeful that this review will clarify Rosaceae fruit sugar alcohol concentrations and individual sugar composition; examples of non-Rosaceae fruit and prepared foods containing sugar alcohol are included for comparison. A brief summary of sugar alcohol and health will also be presented.

(14)C-Assimilate pattern and kinetics of photosynthetic (14)CO 2-assimilation of the marine red alga Bostrychia scorpioides

Occurrence and metabolism of dulcitol and sorbitol in the marine red alga Bostrychia scorpioides (Huds.) Mont. (Ceramiales: Rhodomelaceae) were investigated. Both hexitols are rapidly (14)C-labelled during photosynthesis in a H(14)CO3-seawater medium and are accumulated at comparable rates. The absolute quantity amounts to about 3.2% on a dry weight basis; the percentage of (14)C-labelling after 60 min is 30% for dulcitol and 40% for sorbitol. Additionally small amounts of free [(14)C] glucose were found. Pulse labelling experiments and changes in specific activity provide evidence that both hexitols are rapidly available respiratory substrates, which, however, are probably not interconvertible with polymeric compounds. Some chemotaxonomic aspects are discussed.