Evaluation of the nutritional composition of selected commercially grown berries in Sri Lanka and jam prepared from these berries

Abstract

Berry fruits are consumed because of their attractive color and characteristic taste, and they are considered one of the richest sources of nutrients and natural antioxidants. Their consumption has been linked to the prevention of chronic and degenerative diseases. The term ‘berry fruits’ encompasses the ‘soft/pulpy fruits’, primarily strawberry, currants, gooseberry, blackberry, raspberry, blueberry and cranberry. This study investigates the physicochemical, proximate and mineral composition of fresh and processed berry fruits grown in Sri Lanka, including blackberry (Rubus fruticosus), blueberry (Vaccinium corymbosum), raspberry (Rubus idaeus) and strawberry (Fragaria ananassa) along with jam prepared from these berries. The analysis focused on brix values, pH, titratable acidity, moisture, ash, fat, protein, crude fiber, carbohydrates and mineral content (Ca, Fe, Mg, P, K, Na). Among fresh berries, blueberries recorded the highest brix (13.53±0.33%), while strawberries showed the lowest (6.73±0.13%). For jams, blackberry jam had the highest brix (67.73±0.89%), with raspberry jam the lowest (64.20±0.24%). pH ranged from 2.63±0.02 in fresh blueberries to 3.29±0.01 in fresh strawberries; in jams, the lowest was 2.60±0.01 in blueberry jam, and the highest was 3.24±0.01 in strawberry jam. Moisture content varied significantly, with fresh strawberries having the highest (89.44±0.57%) and blueberry jam the lowest (14.90±0.43%). Fresh raspberries recorded the highest protein (2.68±0.05%) and crude fiber (5.22±0.44%), while the blueberry jam contained the highest carbohydrate content (81.97±0.004%). Mineral content also varied notably, with fresh blueberries showing the highest calcium (0.017±0.0003 mg/g), and fresh strawberries containing the highest phosphorus (12.76±0.847 mg/g) and potassium (0.256±0.022 mg/g). Processed samples, particularly blackberry jam, generally exhibited elevated iron, magnesium, and phosphorus levels. These findings provide valuable insights into how processing influences the nutritional composition and health-promoting qualities of berry-based products.