Effects of process parameters on the properties of barley containing snacks enriched with brewer’s spent grain

Abstract

Brewer's spent grain (BSG), a by-product of malting of barley in the production of malt extract, was used as an ingredient in extruded barley-based snacks in order to improve the nutritional value of the snacks and widen the applications of this by-product in food sector. The effects of the extrusion parameters on the selected properties of the snacks were studied. Snacks with different ingredients including whole grain barley flour, BSG, whey protein isolate (WPI), barley starch and waxy corn starch were produced in 5 separate trials using a co-rotating twin-screw extruder. Extrusion parameters were water content of the mass (17-23 %), screw speed (200-500 rpm) and temperature of the last section and die (110-150°C). Expansion, hardness and water content of the snacks were determined. Snacks containing barley flour and BSG (10 % of solids) had small expansion and high hardness. Addition of WPI (20 % of solids) increased expansion only slightly. Snacks with high expansion and small hardness were obtained when part of the barley flour was replaced with starch (barley or waxy corn). Yet, the highest expansion and the smallest hardness were achieved when barley flour was used with barley starch and WPI without BSG. Furthermore, expansion increased by increasing screw speed and decreasing water content of the mass in most of the trials. This study showed that BSG is a suitable material for extruded snacks rich in dietary fiber. Physical properties of the snacks could be improved by using barley or waxy corn starch and WPI.

Brewers’ spent grain in food systems: Processing and final products quality as a function of fiber modification treatment

“…Textural properties are a combination of mechanical, geometrical, and surface characteristics of the products (Ačkar et al., 2018). Generally, BSG increases the hardness of bread (Aprodu et al., 2017; Ktenioudaki et al., 2015; Magabane, 2017; Roth, Schuster, et al., 2016; Steinmacher et al., 2012; Waters et al., 2012), extrusion products (Ačkar et al., 2018; Kirjoranta et al., 2016; Thorvaldsson, 2020; Żelaziński et al., 2017, 2018), cookies, baked snacks, crackers and biscuits (Heredia‐Sandoval et al., 2020; Ktenioudaki, Crofton, et al., 2013), and cheese blocks (Abd El‐Moneim et al., 2018). Other parameters studied regarding the textural properties include elasticity for bread and pasta; fracturability for extrusion products; and crispness for cookies, baked snacks, crackers, and biscuits.…”

Brewer’s Spent Grains—Valuable Beer Industry By-Product

“…However, they fall out worse compared to cookies made of wheat flour only, which were rated 5 (“like very much”) [ 154 ]. Moreover, the addition of BSG flour to wheat flour in ratio 1:4 may decrease the glycemic index of cookies [ 155 ]. A similar ratio of wheat flour to BSG flour (3:1), according to the researchers, had the best taste qualities among the cookies from the research trials [ 154 ].…”

“…However, the content of a large amount of water-insoluble fibre—lignin and cellulose increase the hardness of snacks, which directly causes worse taste qualities. This effect can be mitigated by adding corn starch and whey protein isolate [ 155 ]. In the case of crispy-slices production, the content of 10% of flour from BSG did not affect the taste and consistency of crispy-slices and contributed to an increase in the fibre content in the produced snack [ 159 ].…”

Extruded snacks from industrial by-products: A review

“…Adding brewer's spent grain did not lower the glycaemic index of the extruded snacks, probably due to other factors preventing a steeper decrease, such as the increase in starch digestibility. Kirjoranta, Tenkanen, and Jouppila (2016) were "high fibre" (10-17%) and recipes containing whey protein isolates and starches expanded well.…”