# Haskap Juicing Method Effects on Haskap Juice Quality
## 3 Results and Discussion
### Total Phenolics Contents and Antioxidant Activities Affected by Juicing Methods  
The total phenolics content of the juices was analyzed spectrophotometrically with the Folin-Ciocalteu method [58]. Therefore, the assays were performed to detect the reductive capacity of the total phenolics in haskap juices. The results (Figure 2) indicated that the juicer produced juices contained about two times amount of total phenolics compared with steam juicer juices (150 GAE mg/mL). The total phenolics in the press juices was approximately 200-250 GAE mg/mL. In our research, we used methanol extraction methods, which were reported to have a relatively high extraction yield compared to acetone extraction methods [59]. \begin{table}
\begin{tabular}{c c c c} \hline
**Treatment** & **Malic Acid (g/L)** & **Citric Acid (g/L)** & **Tartaric Acid (g/L)** \\ \hline Steam juicer & 1.09 \(\pm\) 0.37 \({}^{\text{a}}\) & 3.54 \(\pm\) 0.38 \({}^{\text{a}}\) & 0.64 \(\pm\) 0.22 \({}^{\text{a}}\) \\ Press & 1.7 \(\pm\) 0.42 \({}^{\text{b}}\) & 3.18 \(\pm\) 0.28 \({}^{\text{a}}\) & 0.54 \(\pm\) 0.17 \({}^{\text{a}}\) \\ Juicer & 1.71 \(\pm\) 0.14 \({}^{\text{b}}\) & 3.36 \(\pm\) 0.11 \({}^{\text{a}}\) & 0.71 \(\pm\) 0.24 \({}^{\text{a}}\) \\ \hline \end{tabular} Enzymatic method was used to detect malic acid, citric acid, and tartaric acid amounts in processed juice. The specific acid amount by each column was represented by the mean \(\pm\) standard deviation results of triplicate sample analysis from each treatment. Different superscript letters in the same column indicate significant difference at \(p<0.05\) separated via Tukey’s HSD.  
\end{table} 
Table 3: Malic acid, citric acid, and tartaric acid amounts in processed juice. It has been reported that the antioxidant capacities in plant materials were largely correlated with total phenolics content [60], and our results also generally supported this. The antioxidant activities were examined via two different assays in haskap juices (Figure 3), DDPH and FRAP. The DPPH assay is considered an accurate and economic method to evaluate the radical scavenging activity of antioxidants in a compound, an extract, or other biological sources [61]. The FRAP assay is also used to determine the antioxidant activities in different tissues from varieties of plants [62]. FRAP showed the similar trend of antioxidants differences in the three treatments, although the differences were not significant. The DPPH assay indicated that antioxidant activities were the highest in centrifugal juicer-processed juices, followed by the juices from the press and steam juicer. Figure 1: Total anthocyanin content in different juices. Juicing methods include the steam juicer (steam in the figure), wine press (press in figure), and centrifugal juicer (juicer in figure). Each value of each treatment is an average of three replicate measurements \(\pm\) standard deviation. Different letters above each bar indicate statistically significant difference (\(p<0.05\)) separated via [PERSON]’s HSD. Figure 2: Total phenolics content was affected by haskap juicing methods, including steam juicer, press and the centrifugal juicer. Each method contains three replicates, and each sample has three technical replicates. Total phenolic assay is expressed as gallic acid equivalent (GAE mg/mL). Each value of each treatment is an average of three replicate measurements \(\pm\) standard deviation. Different letters above each bar indicate statistically significant difference (\(p<0.05\)) separated via [PERSON]’s HSD. Although our tests were all determined by colorimetry, the principles of detecting antioxidants and antioxidant activity were different. The [2,2-di(4-tert-octylphenyl)]-1-picrylhydrazyll (DPPH) assay was based on an antioxidant reaction with free organic radicals. The total phenolic assay was performed using Folin-Ciocalteu solution to detect the reductive capacity of antioxidants. The FRAP assay was performed to measure the antioxidant potential through the reduction of Fe (III) to Fe (II) by antioxidants [22].