Characteristics of wild blueberry–soy beverages

Wild or lowbush blueberries (Vaccinium angustifolium Ait.) and soybeans (Glycine max L.) contain a variety of health-protective phytochemicals. The flavor of blueberries could mask beany flavors in soy beverages and thus broaden the appeal of soy. Four formulations were tested in a 2×2 design. Two sources of soy protein (isolate and soymilk powder) and two sweeteners (brown rice syrup and a blend of apple and white grape juice concentrates) were evaluated. All formulations contained 12 g wild blueberry juice concentrate per 100 g total. Total anthocyanins and phenolics were measured spectrophotometrically; antioxidant activity was assessed with the DPPH method. Color, soluble solids, titratable acidity (TA), viscosity, and pH were also measured. A ten-person descriptive panel evaluated flavor, aroma, and textural attributes. Sixty-five consumers rated color, flavor, texture, and overall acceptability. Pasteurized beverages averaged 35 mg of anthocyanins per 100 g. TA and Brix/acid ratio were highest in the soy isolate-juice blend product. Viscosity was lowest in the soy isolate and rice syrup formulation. The descriptive panel rated the isolate-juice sample as having more sweetness and blueberry flavor; soymilk samples had higher painty, nutty, and chalky ratings. Only the isolate-juice blend received mean hedonic scores above “like slightly.”