Color Stability and Bioactive Compound Retention in Patagonian Berry Pulps: Comparative Study of Pasteurization and Freezing Treatments

The visual appeal of berry-based products is primarily driven by their intense color, which is associated with anthocyanin content and antioxidant activity. However, processing and storage can compromise both. This study evaluated color evolution and compound stability in pulps of four Patagonian berries subjected to pasteurization (85 °C, 15 min) or freezing (−18 °C) for 12 months: blackberry (cv. Thornfree), raspberry (cv. Tulameen), sour cherry (cv. Montmorency), and blueberry (cv. Elliot). Color parameters (L*, a*, b*, Chroma, Hue angle, ∆E), total phenolics, flavonoids, anthocyanins, ascorbic acid, and antioxidant activity (DPPH) were analyzed at 0, 3, 6, and 12 months. After pasteurization, anthocyanin retention ranged from 41% in raspberry to 65% in blueberry, with ∆E values exceeding 6.0 in raspberry and sour cherry, indicating perceptible color degradation. Frozen samples showed higher retention (>70% in all cases), with ∆E values below 3.0 in blueberry and blackberry. Hue angle shifts were more pronounced in pasteurized raspberry (11°) and sour cherry (8°), suggesting pigment breakdown. Notably, blueberry and blackberry pulps showed superior color and compound stability across both treatments, attributed to their higher baseline anthocyanin content (35.4 and 41.7 mg/100 g FW, respectively). Ascorbic acid was more labile, with 48–54% losses in pasteurized raspberry and sour cherry, while frozen pulps retained over 70%. Flavonoid retention ranged from 58 to 75% in frozen samples versus 46 to 59% in pasteurized ones. Total phenolics showed a milder reduction, averaging 12–18% loss in frozen and up to 25% in pasteurized pulps. These findings emphasize the importance of selecting appropriate preservation methods to maintain visual and functional quality in fruit-based products.