Incorporation of soybean by-product okara and inulin in a probiotic soy yoghurt: texture profile and sensory acceptance

Abstract

Background: This study evaluated the effect of inulin and okara flour on textural and sensory properties of probiotic soy yoghurt (SY) throughout 28 days of storage at 4 °C. Employing a 2(2) design, four formulations of SY produced from soymilk and fermented with an ABT-4 culture (Lactobacillus acidophilus La-5, Bifidobacterium animalis Bb-12 and Streptococcus thermophilus) were studied: SY-C (control); SY-I (with inulin); SY-O (with okara); SY-IO (with inulin + okara).

Results: The addition of okara and the refrigerated storage led to significant differences in the instrumental texture parameters of SY (P < 0.05). Inulin and okara did not affect SY sensory acceptability (P > 0.05), but there was a tendency for higher scores in the presence of inulin. On the other hand, the storage period, particularly at 21 days, was unfavourable regarding the acceptance of the different SY.

Conclusion: The results showed that the addition of okara flour and the storage were significant factors to increase firmness of the soy yoghurts. SY acceptability was not affected by the incorporation of inulin or okara. These results suggest that okara, discarded as industrial waste, may be used in probiotic soy yoghurt, helping to increase the nutritional and functional properties without altering its acceptability.

Keywords: inulin; okara; probiotic; sensory evaluation; soy yoghurt; texture profile analysis.