Study galactoglucomannan as a feed binder The Center for Feed Technology and the Norwegian Universi- ty of Life Sciences have evaluated how galactoglucomannan (GGM) and its derivates − derived from the spruce tree (Picea abies) treated with steam explosion technology − may influ- ence better binding ability between wheat-based particles under 1 mm in diameter. The materials used for this experi- ment were wheat flour, wheat starch and wheat protein con- centrate. Experimental work was done using a single-die pel- let press with total control of moisture, pelleting load and temperature during compaction. Control treatments were based on guar gum (B5) and LignoBond DD (B6). Tested inclu- sion rates for all binders were 0.25%, 0.5% and 1%. Binder 1 (B1) was based on 83% GGM, binder 2 (B2) on 98% GGM, while binder 3 (B3) had partially deacetylated GGM and binder 4 (B4) fully acetylated GGM.


Promising results The experimental work with wheat flour shows that all novel binders can be successfully used in the pelleting process, with the conclusion that pressure at initial flow (p-max) decreased when the inclusion rates for binder 1 and 2 were increased. The acetylation process of the binding material increased the p-max, independently of its degree of acetylation. However, this increase was not significant for the control binders when used in wheat flour. For wheat protein concentrate and starch material no differences in p-max were observed by adding different binders. Lower p-max can result in less use of electrical energy during commercial pelleting. The tensile strength of the wheat flour pellets was not influ- enced by different binding agents when compared to the control binders B5 to B6. Variables related to different binders and their inclusion rate in the wheat starch compacts were non-significant when compared to the control binders. How- ever, the tensile strength between B1, B2, B3 and B4 was sig- nificantly different, with the lowest tensile strength for B2 (0.5%) and the highest for B1 (0.5%). The tensile strength of the pellets made of wheat protein concentrate was not signif- icant when compared to guar gum and lignosulphonate. However, the tensile strength of the wheat protein pellets in B1 and B3 at level 0.5% were different (p<0.05) from B1 and B2 at the 0.25% level, and B6 at the levels 0.25% and 0.5%. The highest tensile strength was observed at B6, level 1.0% and the lowest was at B3 level, 0.5% (Figure 1).


Effect on water activity Different binders influenced overall water activity (aW) meas- urements. Significant aW differences (p<0.05) were observed at all inclusion levels between the control binders and B3 − for pellets based on wheat protein concentrate. The highest aW was observed at B2, 1.0%, while the lowest were B3 and B4 at 1.0%. The aW of the pellets made with wheat flour was affected by different binders and their inclusion levels.


Control binder B6 had the strongest effect on reducing water activity, with no significant differences between addition levels. A clear tendency for changes in aW in the wheat starch pellets was not observed. For different binders a small change in aW was correlated with hardness, but only for the pellets based on wheat flour (Figure 2). For other wheat- based materials such a correlation was not observed.


Novel feed binders can be used successfully Novel feed binders obtained from forest biomass after steam explosion and based on different purities of galactogluco- mannan and its level of acetylation can be used to bind feed particles, without reducing the hardness of the pellets based on wheat flour, wheat starch and wheat protein concentrate.


Figure 2 - Correlation between tensile strength (N/mm) and water activity (aw) of wheat flour.


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12 10 8 6 4 2 0


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y = 34.462x - 4.9297 R2 = 0.2425 r = 0.49


p-value = 0.002


Novel feed bind- ers obtained from forest bio- mass can be used to bind feed particles.


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0.34


0.36


0.38 Water activity (aW) ▶ ALL ABOUT FEED | Volume 29, No. 3, 2021 15


0.4


0.42


0.44


PHOTO: ANNA SADOVSKAIA Tensile strength/Hardness


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