*2.2. Quality Evaluation Tests*

2.2.1. Weight Loss, Decay Incidence, and Pericarp Browning Index

Weight loss was determined by weighing the fruit on day 0 and then every third day, and the results were expressed as percentages. Fruit showing visible decay symptoms on the surface were considered decayed, and all the decayed fruit were counted and the decay percent was calculated using the following formula:

$$\text{Percentage of fruit decay } = \frac{\text{Number of decayed fruit}}{\text{Total number of fruit}} \times 100\tag{1}$$

The pericarp browning index (BI) of longan fruit was determined by observing the amount of total brown area on each fruit surface, whereby 1 = 0% (no browning), 2 = 1–10% (slight browning), 3 => 10–25% (moderate browning), 4 => 25–50% (severe browning), 5 => 50%, calculated using the below equation [20]. Fruit with a browning scale above 3 was the limit of acceptability:

$$\text{BI} \, = \sum \frac{\text{Browning level} \times \text{number of fruit at each browning level}}{\text{Total number of fruit in the treatment}} \tag{2}$$

2.2.2. Color, Firmness, Total Soluble Solids, Titratable Acidity, and pH

Pericarp color (L\*, a\*, b\*) was measured using a Konica Minolta Spectrophotometer (CM-3600d, Konica Minolta Sensing Inc., Tokyo, Japan) using 3 fruit samples from each replicate. The firmness of the peel was measured using a texture analyzer (TA.XT Plus 10752, Godalming, UK) in compression mode. A 2-mm-diameter plunger was used to puncture the fruit to a depth of five mm at a speed of 20 mm min−1. The maximum force needed to penetrate the fruit was recorded in newtons (N). A total of 3 fruit samples were used for each test from each replicate. For TSS, TA, and pH, the flesh of about 15 fruit samples from each replicate was ground, filtered through muslin cloth, and clear juice was obtained. TSS was determined using a digital Abbe refractometer (Way-2S, Shanghai Shenguang Instruments and Instrument Co. Ltd., Shanghai, China. Titratable acidity (TA) was carried out via the titration of juice with 0.1 N NaOH. The pH of the longan juice was determined using a pH meter (FE28, Mettler Toledo Co. Ltd., Shanghai, China). TSS, TA, and pH were conducted in triplicate.
