engleski

Browning development in bakery products enriched with food industry by-products

During baking, the formation of colour is due to the Maillard reaction, and caramelization of sugars. The formation of colour in bakery products during baking is widely known as browning. As well as baking, the development of browning in bakery products is a simultaneous heat and mass transfer process that occurs mostly in a non-ideal system under non-ideal conditions. Besides the major influence of this phenomenon on the initial acceptance of products by consumers, it is the responsible for other relevant changes occurring in food during baking, i.e. production of flavour and aroma compounds, formation of toxic products (e.g. acrylamide), and decrease of nutritional value of proteins. The present work investigates the effect of some dietary fibres from different origins (apple pomace (AP), brewers' spent grain (BSG)) on the bread crust and crumb colour changes during baking. AP, as inexpensive and primary by- product of apple juice and cider production, is a good source of dietary fibres, polyphenols and pectin. BSG is the major by-product of the brewing industry and a good source of protein, cellulose, noncellulosic polysaccharides, chiefly arabinoxylans and lignin. Because of that, the aim of this study was to investigate the effect of AP and BSG addition (5, 10 and 15%) on bread crust and crumb colour. Colour was measured using a colorimeter. Lightness, redness and yellowness of bread samples fortified with different percentages of BSG were measured as L*, a* and b* value respectively. The change in dark colour was due to the incorporation of AP and BSG. L* value decreased with the increase of addition of AP and BSG. In contrast a* and b* values increased with increasing AP and BSG addition respectively. Colour measurement data indicated that samples with addition dietary fibres (AP and BSG) were darker. Total colour change (∆E) and browning index (BI) increased proportionally to dietary fibres addition, with more pronounced change in samples with AP addition.

bread; non-enzymatic browning; colour; apple pomace; brewers' spent grain

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