# Quality Characteristics and Flavor Analysis of Five Mulberry Varieties
## 3 Results and Discussion
### Amino Acid  
Amino acids play a major role as essential nutrients and flavor enhancers. The quantity and arrangement of amino acids are substantial determinants of food taste [40]. In total, 21 amino acids were identified in mulberries. The amino acid measurements closely align with those reported by [PERSON] et al. (2015) (Table 2). White Shahtoot Mulberry had the highest total amino acid content (5689.05 \(\pm\) 134.6 mg/kg), followed by Zhongsang 5801, Jialing 40, Yuesang 10, and 2000-3 in descending order of magnitude. Of these varieties, essential and non-essential amino acids were present in the highest quantities in White Shahtoot Mulberry (908.01 \(\pm\) 43.7 mg/kg and 4382.07 \(\pm\) 86.63 mg/kg, respectively). The 2000-3 variety had the lowest quantities of essential and non-essential amino acids (229.69 \(\pm\) 14.73 mg/kg and 2147.01 \(\pm\) 398.82 mg/kg, respectively). \begin{table}
\begin{tabular}{l l l l l l l} \hline \hline
**Index** & **Cultuvar** & **Zhongsang** & **2000-3** & **Jialing 40** & **Yuesang 10** & **White Shahtoot** \\  & **5801** & & & & & & **Mulberry** \\ \hline \multirow{8}{*}{Soluble sugar} & Fructose & 38.89 \(\pm\) 6.55 a & 39.66 \(\pm\) 11.31 a & 22.51 \(\pm\) 2.90 ab & 19.75 \(\pm\) 1.04 b & 31.19 \(\pm\) 7.82 a \\  & Glucose & 26.19 \(\pm\) 6.29 a & 18.63 \(\pm\) 3.72 a & 6.43 \(\pm\) 4.59 b & 16.25 \(\pm\) 2.20 ab & 16.83 \(\pm\) 4.44 a \\  & Sucrose & - & - & - & - & - \\  & Maltose & - & - & - & - & - \\  & Lactose & - & - & - & - & - \\ \hline \multirow{8}{*}{Organic acid} & Oxalic acid & 0.07 \(\pm\) 0.00 c & 0.10 \(\pm\) 0.01 a & 0.08 \(\pm\) 0.00 b & 0.07 \(\pm\) 0.00 c & 0.03 \(\pm\) 0.00 d \\  & Tartaric acid & 0.11 \(\pm\) 0.01 b & 0.08 \(\pm\) 0.00 c & 0.08 \(\pm\) 0.00 c & 0.09 \(\pm\) 0.00 b & 0.16 \(\pm\) 0.02 a \\  & Malic acid & 1.33 \(\pm\) 0.01 d & 1.85 \(\pm\) 0.05 a & 1.26 \(\pm\) 0.07 d & 1.44 \(\pm\) 0.01 c & 1.54 \(\pm\) 0.07 b \\  & Lactic acid & - & - & - & - & - \\  & Ascorbic acid & - & - & - & - & - \\  & Acetic acid & - & 0.04 \(\pm\) 0.01 a & - & 0.02 \(\pm\) 0.00 a & - \\  & Citric acid & - & - & - & - & - \\  & Succinic acid & - & - & - & - & - \\ \hline \end{tabular} _“-” indicates that the device was not detected. The values of different lowercase letters in the same line differ significantly (\(p\) < 0.05)._  
\end{table} 
Table 1: Soluble sugar content and organic acid content of different mulberries (g/kg). Significant variations were observed in the free amino acid profiles of the five mulberry varieties. The highest theanine, glycine, alanine, and proline contents were observed in Zhongsang 5801. The highest glycine and serine contents were found in 2000-3. The highest glutamine and isoleucine contents were found in Jialing 40. The highest aspartic acid and valine contents were observed in Yusang 10. The highest glutamic acid, asparagine, threonine, histidine, arginine, methionine, leucine, aminobutyric acid, and phenylalanine contents were observed in White Shahtoot Mulberry. Notably, White Shahtoot Mulberry had significantly higher concentrations of glutamic acid (811.48 \(\pm\) 40.87 mg/kg), asparagine (1406.01 \(\pm\) 87.42 mg/kg), and aminobutyric acid (368.86 \(\pm\) 5.81 mg/kg) than the other varieties (\(p\) < 0.05). Glutamic acid contributes to the umami taste perception in fruits. Among the studied varieties, Zhongsang 5801 had the highest proline content at 88.06 \(\pm\) 6.09 mg/kg, which was approximately seven times that of Yuesang 10. Jialing 40 had significantly higher glutamine levels, at 265.65 \(\pm\) 54.93 mg/kg, than the other varieties tested herein. A higher alcohol content is the by-product of alcoholic beverage fermentation, and its high content is harmful to physiological health. [PERSON] et al. found that a higher content of alcohol was significantly negatively correlated with the content of corresponding amino acids [41]. The content of amino acids of White Shahtoot Mulberry was higher than that of the other four mulberry varieties.