Black chokeberry (Aronia melanocarpa) fruits are among the richest sources of polyphenols and anthocyanins in plant kingdom and suitable raw material for production of functional foods. The popularity of chokeberries is not only due to their nutritional value but also to the constantly emerging evidence for their health-promoting effects. The current study presents detailed information about the content and composition of sugars, organic acids, and polyphenols in 23 aronia samples grown under the climatic conditions of Bulgaria, in 2016 and 2017. Sorbitol was found to be the main carbohydrate of fresh aronia fruits. Its content was in the range 6.5–13 g/100 g fresh weight (FW), representing 61%–68% of low-molecular-weight carbohydrates. Organic acids were represented by substantial amounts of quinic acid (average content 404.4 mg/100 g FW), malic acid (328.1 mg/100 g FW), and ascorbic acid (65.2 mg/100 g FW). Shikimic acid, citric acid, oxalic acid, and succinic acid were found as minor components. Chokeberries were particularly rich in proanthocyanidins, anthocyanins, and hydroxycinnamic acids. The total polyphenol content of aronia fruits varied between 1022 mg/100 g FW and 1795 mg/100 g FW and ORAC antioxidant activity from 109 µmol TE/g to 191 µmol TE/g FW. We also investigated the relationship between the chemical composition of berries and chemical compositions and antioxidant activity of aronia functional drinks—juices and nectars. The differences in the chemical composition of the fruits resulted in functional foods that differ significantly in their chemical composition and antioxidant activity. Additionally, we demonstrated that temperature of juice pressing and nectar extraction has a profound effect on the polyphenol content and composition of these products. This is very important since differences in the chemical composition of raw chokeberries and variation of technological parameters during processing could result in functional foods with different chemical composition, rendering different biological activity.

Rosmarinic acid (RA), an ester of caffeic acid and 3,4-dihydroxyphenyllactic acid, is a potent radical scavenger, a chelator of prooxidant ions, and an inhibitor of lipid peroxidation. RA-containing extracts are widely used natural antioxidants in food products, and many herbal preparations and food supplements, containing RA, are marketed with claims of beneficial health effects. The current study investigated the effectiveness of subcritical water extraction (SWE) for the recovery of RA from lemon balm (Melissa officinalis), as a “green” alternative to conventional hydro-alcoholic extraction. Different durations (10 min and 20 min) and extraction temperatures (100 °C and 150 °C) were applied. Subcritical water applied at a temperature of 100 °C was equally efficient as 50% ethanol in extracting RA. However, the further elevation of temperature to 150 °C decreased RA content by up to 20% due to thermal degradation. The content of RA in dried extracts was between 2.36% and 5.55% and the higher temperature of SWE increased extract yield by up to 41%. The higher extraction yield resulted from the degradation of plant material by subcritical water as evidenced by the increased extraction and degradation of proteins, pectin, and cellulose. These results reveal that SWE is an efficient technology for the extraction of RA and other antioxidants from lemon balm at reduced extraction time and without the use of toxic organic solvents. Furthermore, by modification of SWE conditions, dry extracts with different purity and content of RA are obtained. These extracts could be used in the food industry as food antioxidants, or in the development of food supplements and functional foods.