POWDERED SOUPS MADE WITH BLACK OR BUTTER BEANS: SENSORY EVALUATION AND STABILITY DURING STORAGE

Common beans (Phaseolus vulgaris), such as black and butter varieties, are widely
consumed in Brazil. However, broken beans resulting from processing are either discarded or used as
animal feed. In this study, two powdered soups made with broken black or butter beans were
obtained using two drying methods (oven drying and freeze-drying), without the addition of
synthetic preservatives or antioxidants. Both the powdered soups were evaluated in relation to
water activity (Aw), color parameters (CIELAB), sensory characteristics (affective test), and oxidative
stability (TBARS) in transparent polyethylene packaging at room temperature. According to the
judgers, the freeze-dried soups had higher sensory acceptance than the over drying soups due to
their close resemblance to cooked beans, and the black bean soup showed the best result for
purchase intention. During storage, the Aw of powder soup made with black beans increased from
0.2 to 0.5 after 30 days, while the butter bean powder kept the initial Aw (0.2) during the same
period. The color parameters of freeze-dried black bean powder soup (L* = 22.3, a* = 1.5, b* = 12.9)
exhibited an increase in luminosity after 26 days (ΔL* = 6.7, Δa* = 0.4, Δb* = 1.4), indicating loss of
color, while butter bean powder soup did not alter (L* = 57.4, a* = 13.7, b* = 30.6). After 21 days of
storage, perceptive off-flavor of oxidative rancidity were observed for the black bean powder soup,
confirmed by TBARS values (1.7 mg malonaldehyde/kg oil), while the butter bean powder showed
similar results after 37 days (1.4 mg malonaldehyde/kg oil). Therefore, future researches involving
changes in processing, such as appropriate packaging design and natural/synthetic antioxidant
addition should be conducted aiming to extend the shelf life of both products.