# Effect of Microwave-Assisted Processing of Acorn Flour on Muffin Quality
## 3 Results and Discussion  
### Effect of Microwave Treatment on Moisture Content and Color Characteristics of Acorn Flour  
Acorn flour was subjected to microwave treatment using two approaches: dry and wet systems. The results demonstrated that microwave processing significantly affected the moisture content of the acorn flour samples (Figure 1). Regardless of the treatment system (dry or wet microwave application), both the power level and duration of microwave exposure influenced the efficiency of water removal. Higher microwave power resulted in lower residual moisture content in the samples at a given processing time. For acorn flour subjected to dry microwave treatment for 1.0 min, the moisture content decreased to 5.43%, 3.69%, and 1.51% at 925 W, 1295 W, and 1850 W, respectively. These values correspond to moisture reductions of 46.9%, 63.9%, and 85.5% relative to the untreated control sample (AF_0). In the case of wet microwave treatment under the same processing time (1.0 min), the moisture content was 48.21%, 46.41%, and 40.40% at 925 W, 1295 W, and 1850 W, respectively, representing reductions of 19.8%, 22.8%, and 32.8% compared to the wet control sample (AF_W_0). With respect to processing time, longer exposure consistently leads to lower moisture content. Notably, the rate of moisture reduction in wet-treated samples was slower than in dry-treated ones. This phenomenon may be attributed to the substantially higher initial water content in the wet samples, which, while efficiently absorbing microwave energy, may also have limited penetration depth and energy distribution [45]. Microwave treatment also affected the external appearance of acorn flour, particularly its color, as reflected in changes to the L*, a*, and b* color parameters (Table 1). The most pronounced change was observed in lightness (L*), with flour samples exhibiting progressive darkening in response to microwave exposure. This was evidenced by a decrease in L* values, which intensified with increasing microwave power and processing time. Among the dry microwave-treated samples, the lowest L* value (54.11) was recorded in the sample treated at 925 W for 3.0 min, representing an 11.3% reduction compared to the untreated control. For samples processed for the same duration (1.0 min) but at different power levels, lightness decreased with increasing power, yielding L* values of 58.94, 57.75, and 56.13 for 925 W, 1295 W, and 1850 W, respectively. Wet microwave-treated samples demonstrated substantially lower lightness values than their dry-treated counterparts, with differences reaching up to 51% under identical power and time conditions. A strongercorrelation was observed between processing time and lightness reduction in wet-treated samples. This intensified effect may be attributed to the facilitation of Maillard reactions under high-moisture conditions [46; 47]. Similar flour darkening following microwave treatment has also been reported by [PERSON] et al. [48] in studies on chestnut flour. The a* and b* color parameters of acorn flour were also dependent on the microwave treatment (Table 1). In dry microwave-treated samples, a* values increased with processing time, indicating an intensification of the red color component. The highest a* value was observed in the sample treated at 925 W for 3.0 min, representing a 22.6% increase compared to the untreated control. For the b* parameter, statistically significant differences were noted relative to the control sample, reflecting an enhancement in the yellow color parameter. However, variations in the microwave power and processing time did not result in statistically significant differences among the treated samples. In the case of wet  
Figure 1: Moisture content of acorn flour after dry (**a**) and wet (**b**) microwave treatment. AF—acorn flour; 0—control samples; W—wet microwave treatment; 925, 1295, 1850—microwave power (in watts); 0.5...3.0—duration time (in minutes).