Impact of new ingredients obtained from brewer’s spent yeast on bread characteristics
The impact of bread fortification with β-glucans and with proteins/proteolytic enzymes from brewers’ spent yeast on physical characteristics was evaluated. β-Glucans extraction from spent yeast cell wall was optimized and the extract was incorporated on bread to obtain 2.02 g β-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 β-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 β-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 β-glucan rich extract, not only due to bread β-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 β-glucan rich extract is a promising bread ingredient.
KeywordsBread β-Glucans Proteins Proteolytic enzymes Brewer’s spent yeast
Authors wish to thank FCT, Fundação para a Ciência e Tecnologia the Grant FRH/BD/87461/2012. This work received financial support from the European Union (FEDER Funds POCI/01/0145/FEDER/007265) and National Funds (FCT/MEC, Fundação para a Ciência e Tecnologia and Ministério da Educação e Ciência) under the Partnership Agreement PT2020 UID/QUI/50006/2013.
- AOAC (2000) Official methods of analysis of the Association of Official Analytical Chemists, 17th edn. Association of Official Analytical Chemists, VirginiaGoogle Scholar
- Buera M, Retriella C, Lozano R (1985) Definition of colour in the nonenzymatic browning process. Farbe 33:316–326Google Scholar
- FAO/WHO (1990) Energy and protein requirements. Report of a joint FAO/WHO/UNU Expert Consultation technical report. FAO/WHO and United Nations vol 724, Geneva, SwitzerlandGoogle Scholar
- Martins ZE, Erben M, Gallardo AE, Silva R, Barbosa I, Pinho O, Ferreira IMPLVO (2015) Effect of spent yeast fortification on physical parameters, volatiles and sensorial characteristics of home-made bread. Int J Food Sci Technol 50:1855–1863. https://doi.org/10.1111/ijfs.12818 CrossRefGoogle Scholar
- Petravić-Tominac V, Zechner-Krpan V, Berković K, Galović P, Herceg Z, Srečec S, Śpoljarić I (2011) Rheological properties, water-holding and oil-binding capacities of particulate ß-glucans isolated from spent brewer’s yeast by three different procedures. Food Sci Biotechnol 49:56–64Google Scholar
- Prosky L, Asp NG, Furda I, DeVries JW, Schweizer TF, Harland BF (1985) Determination of total dietary fibre in foods and food products: collaborative study. J Assoc Off Anal Chem 68:677Google Scholar
- Prosky L, Asp NG, Schweizer TF, DeVries JW, Furda I (1988) Determination of insoluble, soluble, and total dietary fibre in foods and food products. J Assoc Off Anal Chem 71:1017Google Scholar
- Russ JC (2011) The image processing handbook. CRC Press, Boca RatonGoogle Scholar
- Zayas IY (1993) Digital image texture analysis for bread crumb grain evaluation. Cereal Food World 38:760–766Google Scholar