The Creaming of Short Doughs and Its Impact on the Quality Attributes of Rotary-Molded Biscuits

Abstract

Scant attention has been given to understanding the impact of creaming stability on the final structure of semi-sweet biscuits, an aspect that has traditionally concerned the biscuit industry. Accordingly, the aim of this study was to analyze the influence of the creaming phase stability on the quality attributes of rotary-molded biscuits. Doughs were formulated with 10.2% of fat (wet basis) and 16.3% of sucrose (w.b.), using two sucrose particle sizes, which were either added directly or after dilution in water at different concentrations. Additionally, the creaming phase was prepared using either a low-shear or a high-shear mixer. The results show that an aqueous-phase migration occurred when the creaming was blended in a low-shear mixer, when using either powdered sucrose or granular sucrose diluted in water at a high concentration. The phase separation was inhibited with the high-shear mixer, which provided a stable creaming. Notwithstanding the variation in creaming stability, no differences were observed in hardness, aeration, sweetness, color and noise intensity. Additionally, the micro-CT analysis revealed that biscuits had a similar microstructure (air porosity and thickness of biscuit walls) when they were prepared with either an unstable or a stable creaming phase. Consequently, creaming stability does not seem to affect the structure and the most relevant sensory attributes of rotary-molded biscuits under this set of experimental conditions, which are representative of those used by the industry for this product category.

Keywords: X-ray micro-CT; creaming stability; granulated sucrose; high-shear mixer; image analysis; low-shear mixer; powdered sucrose; rotary-molded biscuits; sensory profiling.

Figure 1

Elaboration process of rotary-molded biscuits.

Figure 2

Aqueous-phase migration (%) of the creaming phase, which was elaborated using granulated (A,C) or powdered (B,D) sucrose and was then subjected to low-shear (A,B) or high-shear (C,D) mixing. Additionally, sucrose was dissolved in water to obtain the following sugar solutions: 0%ST, 50%ST, 100%ST or >100%ST. Data are mean ± confidence intervals at 95% (n = 3). Different scripts denote significant differences (p < 0.05).

Figure 3

Firmness (N) of the creaming phase, which was elaborated using granulated (A,B) or powdered (C) sucrose and was then subjected to low-shear (A) or high-shear (B,C) mixing. Additionally, sucrose was dissolved in water to obtain the following sugar solutions: 0%ST, 50%ST, 100%ST or >100%ST. Data are means ± confidence intervals at 95%. Different scripts denote significant differences (p < 0.05).

Figure 4

Maximum breaking force (N) of rotary-molded biscuits, obtained by texture analyzer. Biscuits were elaborated using granulated (A,C) or powdered (B,D) sucrose. Sugar was dissolved in water to obtain the following sugar solutions: 0%ST, 50%ST, 100%ST or >100%ST. Further, the creaming phase was subjected to low-shear (A,B) or high-shear (C,D) mixing. Data are means ± confidence intervals at 95%. Different scripts denote significant differences (p < 0.05).

Figure 5

Hardness at the first bite of rotary-molded biscuits, obtained by a trainee sensory panel. Biscuits were elaborated using granulated (A,C) or powdered (B,D) sucrose. Sugar was dissolved in water to obtain the following sugar solutions: 0%ST, 50%ST, 100%ST or >100%ST. Further, the creaming phase was subjected to low-shear (A,B) or high-shear (C,D) mixing. Data are means ± confidence intervals at 95%. Different scripts denote significant differences (p < 0.05).

Figure 6

Sensory attributes (i.e., aeration, noise intensity, grittiness, sweetness, color, thickness) of rotary-molded biscuits. Biscuits were elaborated using granulated (A,C) or powdered (B,D) sucrose. Sugar was dissolved in water to obtain the following sugar solutions: 0%ST (yellow), 50%ST (blue), 100%ST (green) or >100%ST (red). Further, the creaming phase was subjected to low-shear (A,B) or high-shear (C,D) mixing. Data (n = 20) are expressed as observed mean.

Figure 7

2D X-Y cross-sectional images (by X-ray µCT) of biscuits (A) and structure thickness distribution of air pores inside the biscuit structure (B), which were formulated with a sugar solution at 0%ST, using granulated (GS) or powdered (PS) sucrose, and the creaming phase was subjected to low-shear (Hor) or high-shear (HSh) mixing. Porosity is means ± standard deviation (n = 3). Data from air pores distribution are means ± confidence intervals at 95%. Different scripts in each range interval denote significant differences (p < 0.05).

Figure 8

The structure thickness cumulative distribution of the biscuits’ walls, which were elaborated with a sugar solution at 0%ST, using granulated (A,C) or powdered (B,D) sucrose, and the creaming phase was subjected to low-shear (A,B) or high-shear (C,D) mixing. Data are means ± standard deviation (n = 3).