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Haskap berries (Lonicera caerulea L.) are a rich source of bioactive molecules. As such, the extraction of anthocyanins is important for the development of many value-added products and functional food ingredients. In this paper, the ultrasound-assisted extraction (UAE) of anthocyanins from haskap berries was investigated. Significant independent variables were screened and optimized using Plackett-Burman (PB) and Box-Behnken (BB) designs, respectively. The mathematical model showed a high coefficient of determination (R(2)=0.9396) and the optimum conditions for the extraction were as follows: liquid/solid ratio 25:1 (mL/g), solvent composition of 80% ethanol, addition of 0.5% formic acid, ultrasound bath temperature of 35°C for 20 min. Under these conditions, the total anthocyanin content of 22.73 mg cyaniding 3-glucoside equivalents (C3G)/g dry weight (DW) was consistent with the predicted response of 22.45 mg C3G/g DW from the model (mean error of 1.28%). Five anthocyanins were identified in the optimized extract, namely cyanidin 3,5-diglucoside, cyanidin 3-glucoside, cyanidin 3-rutinoside, pelargonidin 3-glucoside, and peonidin 3-glucoside. Thus, UAE is a suitable technique for the extraction of anthocyanins from haskap berries.

BACKGROUND: Haskap berries (Lonicera caerulea L.) are processed into various products (e.g. juice, jam and chutneys). These fruits are rich in bioactive compounds, though losses can occur during frozen storage, affecting the nutritional content of the products. OBJECTIVE: To investigate the effect of freezing storage temperature (-18 and-32 • C) and steam blanching prior to freezing on the the total phenolic content (TPC)/total reducing capacity (TRC), total anthocyanin content (TAC) and antioxidant potential of three Haskap berry varieties; Tundra (T), Berry Blue (BB) and Indigo Gem (IG). METHODS: Berries were stored at-18 or-32 • C for six months, and analyzed monthly for TPC/TRC, TAC, and DPPH radical scavenging activity. Steam blanching prior to freezing was also evaluated. RESULTS: Frozen storage at-18 • C for six months reduced the TPC/TRC by 37.08 to 47.16%. TAC was also reduced, where the highest decrease was for BB (59.24%) followed by IG (46.34%), and DPPH scavenging activity decreased by 26.78 to 30.86%. Blanching prior to freezing improved the retention of bioactive compounds but storage at-32 • C did not yield significant improvements. CONCLUSIONS: Steam blanching prior to freezing followed by frozen storage at-18 • C is recommended for better retention of the bioactive components of haskap berries.