ABSTRACT
The impact of bread fortification with ß-glucans and with proteins/proteolytic enzymes from brewers' spent yeast on physical characteristics was evaluated. ß-Glucans extraction from spent yeast cell wall was optimized and the extract was incorporated on bread to obtain 2.02 g ß-glucans/100 g flour, in order to comply with the European Food Safety Authority guidelines. Protein/proteolytic enzymes extract from spent yeast was added to bread at 60 U proteolytic activity/100 g flour. Both ß-glucans rich and proteins/proteolytic enzymes extracts favoured browning of bread crust. However, breads with proteins/proteolytic enzymes addition presented lower specific volume, whereas the incorporation of ß-glucans in bread lead to uniform pores that was also noticeble in terms of higher specific volume. Overall, the improvement of nutritional/health promoting properties is highlighted with ß-glucan rich extract, not only due to bread ß-glucan content but also for total dietary fibre content (39% increase). The improvement was less noticeable for proteins/proteolytic enzymes extract. Only a 6% increase in bread protein content was noted with the addition of this extract and higher protein content would most likely accentuate the negative impact on bread specific volume that in turn could impair consumer acceptance. Therefore, only ß-glucan rich extract is a promising bread ingredient.
ABSTRACT
The use of agroindustry by-products (BP) for fortification of wheat bread can be an alternative to waste disposal because BP are appealing sources of dietary fiber. Moreover, it may also contribute to indirect income generation. In this study, sensory, color, and crumb structure properties of breads fortified with fiber rich fraction recovered from four types of agroindustry BP were tested, namely orange (OE), pomegranate (PE), elderberry (EE), and spent yeast (YE). Statistical models for sensory preference evaluation and correlation with color and crumb structure were developed. External preference mapping indicated consumer preferences and enabled selection of the concentrations of BP fibre-rich fraction with best acceptance, namely 7.0% EE, 2.5% OE, 5.0% PE, and 2.5% YE. Data collected from image analysis complemented sensory profile information, whereas multivariate PLS regression provided information on the relationship between "crust color" and "crumb color" and instrumental data. Regression models developed for both sensory attributes presented good fitting (R2 Y > 0.700) and predictive ability (Q2 > 0.500), with low RMSE. Crust and crumb a* parameters had a positive influence on "crust color" and "crumb color" models, while crust L* and b* had a negative influence.
