Influence of juice processing factors on quality of black chokeberry pomace as a future resource for colour extraction.

Aronia melanocarpa berries are a rich source of anthocyanins and its pomace, a by-product of juice processing, could be efficiently used for extraction of natural colours for the food industry. This study evaluated the influence blanching, freezing, maceration temperatures (2°C, 50°C) and enzyme treatments before juice pressing on the yield and anthocyanin composition of both juice and pomace. Total anthocyanin levels in pomace were affected mostly by enzyme treatment followed by maceration temperature. The pre-heating of the mash prior to processing increased juice yield and retention of anthocyanins in the pomace. Cold maceration of frozen berries without enzyme addition gave the highest concentrations of anthocyanins in the pomace, and both cold and hot maceration of fresh unblanched berries with enzyme the lowest. The results support future exploitation of natural colours from pomace side streams of Aronia, thus increasing competitiveness of Aronia berry production.

Phenolic compounds in blackcurrant (Ribes nigrum L.) leaves relative to leaf position and harvest date.

Blackcurrant leaves are an essential source of phenolic compounds and this study investigated their variation relative to leaf positions and harvest date. The phenolic content varied between harvest dates, although leaf position on the shoot and interactions also played an important role. The contents of quercetin-malonyl-glucoside, kaempferol-malonyl-glucoside isomer and kaempferol-malonyl-glucoside were higher than that of the other identified phenolic compounds, whereas epigallocatechin was the lowest for all investigated leaf positions and harvest dates. The content of several of the compounds was highest in June, while quercetin-glucoside, kaempferol-glucoside and total phenols, increased towards the end of the season. Leaf position influenced the content of myricetin-malonyl-glucoside, myricetin-malonyl-glucoside isomer, quercetin-malonyl-glucoside and kaempferol-glucoside at the end of the season. Knowledge relating to the influence of ontogenetic and harvest time on the content of specific phenolic compounds might contribute in tailoring functional foods or pharmaceutical products using blackcurrant leaves as natural ingredients.

Phenols and ascorbic acid in black currants (Ribes nigrum L.): variation due to genotype, location, and year.

Black currant berries contain many biochemical compounds with proven or potential human health benefits. We studied the content of total and single polyphenols, ascorbic acid, soluble sugars, and titratable acidity for two advanced selections and three cultivars of black currant at two distant locations in Sweden (south: 56°06'N; north: 65°21'N) over a 3 year period. Regression analyses revealed the effect of genotype to be considerably larger than that of location and year. However, significant effects of location, year, and interactions were also revealed. A principal component analysis nevertheless separated the genotypes. The content of ascorbic acid, total phenols, total anthocyanins, and soluble sugars was highest in berries from the south, whereas the content of phenolic acids and titratable acidity was highest in berries from the north. The results show that selection of cultivars and production sites are important for cultivation of high-quality black currant raw material for health-promoting products.

An optimized method for analysis of phenolic compounds in buds, leaves, and fruits of black currant ( Ribes nigrum L.).

Although the fruits are the economic driver for the black currant industry, the buds and leaves are excellent sources of beneficial phenolic compounds that may contribute to the future value of the crop. In this study, extraction of phenolic compounds for different parts of the black currant plant was optimized, and an efficient method for their separation by HPLC was developed. This allowed the simultaneous quantification of a range of hydroxycinnamic acids, flavan-3-ols, flavonols, and anthocyanins by DAD following their identification by HPLC-ESI-MS(n). A total of 23 compounds were detected in the buds, 22 of which were found in fruit and leaves. To the best of our knowledge, this is the first report of flavonol glycosides of quercetin, myricetin, isorhamnetin, and kaempferol along with hydroxycinnamic acids such as neo-chlorogenic acid and chlorogenic acid in the buds. Additionally, we provide the first evidence of kaempferol-3-O-rutinoside in black currant leaves. This approach offers avenues for superior combined compositional identification and cultivar selection targeted at the generation of polyphenol-rich products derived from the whole crop and not just the fruit.