Baoru Yang

Inositols and methylinositols in sea buckthorn (Hippophaë rhamnoides) berries.

Sea buckthorn (Hippophaë rhamnoides L.) berries, especially of ssp. sinensis, contain significant quantities of an unknown, water-soluble compound, evidently a cyclitol derivative. The compound was isolated by HPLC and analyzed by GC-MS [trimethylsilyl (TMS) derivative, selected ion monitoring (SIM) and total ion chromatogram (TIC) analyses], by (1)H and (13)C NMR and by optical activity measurements. The results together with analyses of reference compound verified the unambiguous structure (-)-2-O-methyl-L-chiro-inositol (L-quebrachitol). In addition, chiro-inositol and myo-inositol existing in trace amounts were identified based on reference compounds, chromatographic data and mass spectra of the TMS derivatives. Methyl-myo-inositol was tentatively identified based on chromatography and mass spectrometry. Inositols and methyl inositols are bioactive compounds essential for regulating physiological processes of plants and humans. To our knowledge, this is the first report on the presence of chiro-inositol and myo-inositol in sea buckthorn and L-quebrachitol in edible berries. The identification of the inositols and l-quebrachitol in sea buckthorn may bring new insights into the sensory properties and also mechanisms behind the health effects of the berry.

Effects of latitude and weather conditions on proanthocyanidins in berries of Finnish wild and cultivated sea buckthorn (Hippophaë rhamnoides L. ssp. rhamnoides)

Sea buckthorn (Hippophaë rhamnoides ssp. rhamnoides) of varieties Terhi and Tytti and one of wild origin were cultivated in southern and northern Finland, harvested during 2007-2013. Proanthocyanidins (PAs) were analyzed with HILIC UPLC-ESI-MS. The southern and northern samples were separated in the partial least squares discriminant analysis model (four factors, R(2) 0.75, Q(2) 0.70). The total PAs were more abundant in berries from the north (610-970mg/100gDW) than in those from the south (340-450mg/100gDW) (p<0.05). In northern Finland, the length of the growth season as well as the temperature sum and radiation sum of the growth season until harvest were negatively correlated with the total PAs in all the samples but positively with PA oligomers in Tytti and Terhi. In southern Finland no respective correlations were seen. Terhi and Tytti had different trends in the content of total PA and oligomers in overripe stages.

Effect of processing technologies and storage conditions on stability of black currant juices with special focus on phenolic compounds and sensory properties.

Juice was pressed from black currants without enzyme treatment (NEB=Non-Enzymatic Berry) followed by re-pressing of the residue with enzymes (EPR=Enzymatic Press Residue) and the results were compared to the conventional enzyme-aided berry pressing (EB=Enzymatic Berry). EPR-juice had 9- and 5-fold higher contents of phenolic compounds compared with the NEB- and EB-juices, respectively. Effect of the low content and stability of phenolics was noticed as loss of the visual color in the NEB-juice during storage. The decrease in monomeric anthocyanins and the increase in phenolic acids were most severe in the NEB-juice, whereas the most significant decline in hydroxycinnamic acid derivatives occurred in the enzyme-treated juices. Storage in light induced less change in the phenolic composition in EPR-juice than in the two other juices. The study gave new knowledge on changes in individual metabolites, in sensory properties and in the shelf life of berry juices.

Improved analysis of anthocyanins and vitamin C in blue-purple potato cultivars

Methods were optimized for extraction and quantification of anthocyanins (ACY) and vitamin C in potatoes. Acidified aqueous methanol (70%) was the optimal extraction solvent and freeze-drying significantly improved the extraction yield of ACY. The content of ACY varied widely in five potato cultivars from 0.42 to 3.18mg/g dry weight, with the latter being the highest value found in the Finnish cultivar Synkeä Sakari. Compared with dithiothreitol (DTT), tris(2-carboxyethyl) phosphine hydrochloride (TCEP) was more efficient in reducing dehydroascorbic acid (DHA) to ascorbic acid (AA) and for quantifying the content of total ascorbic acid (TAA). For raw potatoes, quantification of TAA after treatment with TCEP was more reliable than a direct analysis of AA, whereas AA can be analyzed directly in steam-cooked samples. The TAA contents in the three potato cultivars were around 0.30-0.35mg/g dry weight. The loss of AA in steam cooking was 24%.

Sensory profile of ethyl β-d-glucopyranoside and its contribution to quality of sea buckthorn (Hippophaë rhamnoides L.)

The contribution of ethyl β-d-glucopyranoside (EG) to sensory profile of sea buckthorn (Hippophaë rhamnoides ssp. rhamnoides) was studied. The content of natural existing EG varied between 0.6 and 19.8g/L in the sea buckthorn studied. The taste threshold of pure EG was estimated in water solution as 1.1±1.3g/L, and the suprathreshold aqueous EG solution (5.0g/L) was perceived mainly as bitter. In aqueous sugar-acid mixtures, acids were the major contributors to sourness and astringency, whereas the added EG or sugars showed little impact on the overall sensory profile. EG addition increased the bitterness of sea buckthorn juice. The sensory profiles of the juices were dominated by intense sourness correlating with the malic acid content. The bitterness of the juices correlated with the EG content as well as the ratios EG/acids and EG/sugars. EG content shall be considered when selecting raw materials for industrial processing.