# Quality Monitoring and Analysis of Xinjiang 'Korla'
## 2 Materials and Methods
### Implementation Scenario  
In this research, a long-distance transportation cold chain of 'Korla' fragrant pear was chosen, which began from the orchard and terminated at a retail store and took approximately 12 days. The 'Korla' fragrant pears were harvested in Korla, Xinjiang Uygur autonomous region and then transported to Beijing in China. 'Korla' fragrant pears were kept in a refrigerated truck at about 4 \({}^{\circ}\)C in five-day transportation, the single way cold chain transportation distance is around 3167 km, and the refrigerated truck size is about \(3.0\times 2.5\times 2.4\) m. After being transported to the retail store, two boxes \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Sensor** & **Sensor Type** & **Principle** & \
\begin{tabular}{c} **Measurement** \\ **Range** \\ \end{tabular} & **Resolution** & **Output** &
\begin{tabular}{c} **Response** \\ **Time** \\ \end{tabular} \\ \hline Temperature & \multirow{2}{*}{SHT20} & \multirow{2}{*}{Capacitive} & -40 + 125 \({}^{\circ}\)C & 0.04 \({}^{\circ}\)C & I\({}^{2}\)C & T63 \(<\) 8 s \\ \cline{2-5} Relative humidity & \multirow{2}{*}{SHT20} & \multirow{2}{*}{Band gap} & 0–100\%RH & 0.04\%RH & I\({}^{2}\)C & T63 \(<\) 30 s \\ \cline{2-5} CO\({}_{2}\) gas sensor & & & & & \\ O\({}_{2}\) gas sensor & & & & & \\ C\({}_{2}\)H\({}_{4}\) gas sensor & & & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 1: The sensor list for monitoring in fragrant pear cold chain logistics. Figure 2: The hardware design of the multi-sensor monitoring detector. (**a**) The flow chart of the multi-sensor monitoring detector. (**b**) Hardware of multi-sensor monitoring detector. of 'Korla' fragrant pears were transported to the laboratory at China Agricultural University. During the cold chain logistics of 'Korla' fragrant pears and the storage at the laboratory, three experiments, illustrated in Figure 3, were conducted. Experiment I was performed to monitor the real-time critical microenvironment parameters evolution in the actual 'Korla' fragrant pear cold chain logistics via multi-sensor monitoring detectors and carry out the quality evaluations of 'Korla' fragrant pears after each stage of the cold chain logistics. Experiment II was executed to monitor the critical microenvironment parameters evolution of 'Korla' fragrant pears under refrigeration condition, and measure the critical quality parameters of 'Korla' fragrant pears. One box of 'Korla' fragrant pears was stored in an incubator (LRH-250, Shanghai, China) under 5 \({}^{\circ}\)C to simulate the storage at refrigeration temperature. Experiment III was conducted to monitor the critical microenvironment parameters evolution of 'Korla' fragrant pears under room temperature conditions and evaluate the quality of 'Korla' fragrant pears. Another box of 'Korla' fragrant pears was placed on a table in the laboratory to simulate the storage at room temperature. The multi-sensor monitoring detectors were placed in packages with cardboard boxes after fruit grading to monitor the temperature fluctuation and relative humidity fluctuation and determine the gas microenvironment in the 'Korla' fragrant pear cold chain. The 9 V, 36 Ah rechargeable lithium battery served as a DC (direct current)power supply. The data acquisition and storage intervals of the multi-sensor monitoring detectors were set to 2 min. The length of a stored data packet was 21 bytes, which included the sensor ID (one byte), the temperature data (four bytes), the relative humidity data (four bytes), the CO\({}_{2}\) gas data (four bytes), the O\({}_{2}\) gas data (four bytes), and the C\({}_{2}\)H\({}_{4}\) gas data (four bytes). Sensory evaluation and physicochemical indexes are commonly used methods for evaluation of fruit quality. Sensory properties play a significant role in consumer preferences and they are evaluated respectively by several experts by means of a questionnaire. The existing literature suggests that firmness, pH and total soluble solids content are the representatives and feasible indicators of pear quality [31; 32; 33; 34].