## 3 Results and Discussions
### Effect of Vacuum Impregnation on Physicochemical Parameters  
Table 5 lists the physicochemical properties (pH, TA, TSS, aw, and moisture) of apple slices after vacuum impregnation with _H. sabdariffa_ aqueous extract. All evaluated parameters exhibited statistically significant differences (\(p<0.05\)) between treated and untreated  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Treatment** & **Flavonoids** & **ABTS** & **DPPH** \\  & **(mg CE/100 g Fresh Weight)** & **(mmol TE/100 g Fresh Weight)** & **(mmol TE/100 g Fresh Weight)** \\ \hline Untreated control & 25.36 \(\pm\) 0.43 & 67.98 \(\pm\) 0.64 ** & 82.68 \(\pm\) 1.96 ** \\ T1 & 64.81 \(\pm\) 2.11 ** & 99.74 \(\pm\) 0.67 ** \\ T2 & 53.38 \(\pm\) 4.29 ** & 135.36 \(\pm\) 0.52 ** & 170.11 \(\pm\) 2.74 ** \\ T3 & 61.34 \(\pm\) 2.55 ** & 142.19 \(\pm\) 0.38 ** & 175.21 \(\pm\) 4.13 ** \\ T4 & 53.68 \(\pm\) 2.26 ** & 106.32 \(\pm\) 0.34 ** & 134.20 \(\pm\) 1.04 ** \\ T5 & 54.30 \(\pm\) 1.26 ** & 58.17 \(\pm\) 0.35 ** & 132.87 \(\pm\) 1.77 ** \\ T6 & 60.44 \(\pm\) 0.57 ** & 55.23 \(\pm\) 0.98 ** & 92.96 \(\pm\) 0.17 ** & 169.93 \(\pm\) 0.41 ** & 99.67 \(\pm\) 0.59 ** & 164.65 \(\pm\) 1.48 [FOOTNOTE:4]Footnote 4: Data are presented as mean \(\pm\) standard deviation (\(n=9\)). Statistically significant differences (\(\alpha=0.05\)) among the treatments are denoted by lowercase letters in each apple slices. The VI process resulted in a decrease in the pH values (3.29 to 3.67) of the treated samples compared to the untreated sample (pH of 4.01). Additionally, the TA values of the treated samples significantly increased (\(p<0.05\)) after VI (0.37-0.45% citric acid) in comparison to the untreated sample (0.18% citric acid). [PERSON] et al. [33] reported a decrease in pH (4.24 to 3.90) and an increase in TA (0.24 to 0.36%) in apple slices vacuum impregnated with ascorbic acid, and similar trends were observed in apple tissues vacuum impregnated with black carrot juice [21]. Previous research has indicated that the physicochemical properties (pH, TA, and TSS) of food matrices under VI are influenced by the intrinsic characteristics of impregnation solutions; for instance, an increase in pH has been observed in vacuum impregnated fresh-cut apples with fructose and calcium lactate [42; 43]. A decrease in TSS content was observed in the VI samples (8.20 to 997 \({}^{\circ}\)Brix) compared to the untreated sample (15.03 \({}^{\circ}\)Brix). Similar trends have been reported after VI of black carrot juice in apple tissues [21] or calcium lactate in apple slices [9]. This phenomenon can be attributed to the low TSS content of the HS extract [9]. During the VI process, certain soluble solids in apple slices may be removed while the extract diluted with water entered the apple slice, reducing the TSS content, as explained by [PERSON] et al. [30] during the VI of _Daucus carota_ extract in _Pachynhizus erosus_. In contrast, several authors have reported an increase in the TSS content of vacuum-impregnated fruits; however, in most cases, the impregnation solutions contain added sugars such as fructose or glucose, and this effect could be attributed to the presence of solutes in the solution [4; 19]. Nevertheless, it has also been reported that there are no changes in TSS content after VI fresh-cut apples, which is attributed to the TSS content of the solution used [44] and the sample geometry [39]. Additionally, a statistically significant (\(p<0.05\)) increase in water activity and moisture content was observed in vacuum-treated apple slices compared with the untreated sample (0.94 and 86%). The water activity ranged from 0.92 to 0.98, whereas the moisture content ranged from 84.36 to 88.01%. These values are consistent with those reported in the literature for fresh apples [19; 27; 40; 43]. In jicama slices vacuum impregnated with _Daucus carota_ extract, the water activity varied according to the experimental conditions, and in some treatments, the aw values of treated samples were higher than those of untreated samples [30]. [PERSON] et al.