Whole-matrix effects of blackcurrant and raspberry materials: linking compositional diversity with microbiota-supporting potential

While blackcurrant and raspberry fruits and juices are well-known and valued raw materials in the food industry, other plant parts of these species remain largely unexplored. Therefore, this study compared the contents of polyphenols, carotenoids, chlorophylls, minerals, vitamins, amino acids, sugars, and organic acids and the energy values of the fruits, juices, seeds, seed oils, and leaves of blackcurrants and raspberries. Additionally, the potential of solid substances from the analyzed fruits, juices, seed oils, and leaves to stimulate the growth of Lactobacillus plantarum and Lactobacillus rhamnosus was assessed. Interestingly, fruits rarely contained the highest levels of a given ingredients compared to other plant materials. In 81% of cases, the tested samples stimulated microorganisms to grow more effectively when compared to the control culture cultivated without plant material addition. The highest cell densities of L. plantarum and L. rhamnosus were achieved with the addition of blackcurrant juice and raspberry leaves, which increased their growth by 49- and 32-fold, respectively. The results suggest that microbial growth stimulation may be mostly influenced by the high total organic acid content, sugar levels, and flavan-3-ols in the tested materials. Future research should focus on comparing the health-promoting potential of these materials.