2.5.3. Expansion measurement
Expansion was evaluated as increase in the volume of the mango chips. The bulk volume was measured using n-heptane displacement according to the method of Tabtiang et al. (2012). The expansion ratio (ER) of the sample was then calculated by Nath and Chattopadhyay (2008): ER = Ve/V0
where V0 and Ve are the sample volume before and after puffing (cm3),respectively. All tests were performed in triplicate, and the average values were reported.
2.5.4. Rehydration measurement
Rehydration experiments were performed by immersing approximately 10 g of mango chips into 200 mL of distilled water at 30 C for 180 min. The samples were then withdrawn, drained, gently blotted with paper towels to eliminate the surfacewater and
then weighed. The rehydration ratio (RR) of the sample was calculated by Deng and Zhao (2008b): RR = Mr/M
where M and Mr are the sample mass before and after rehydration (g), respectively. All tests were performed in triplicate, and the average values were reported.
2.5.5. Color determination
The color of fresh mango and mango chips was measured using a colorimeter (CM3000, Minolta, Tokyo, Japan) with a D65 standard illuminant and 10 observer. Approximately 10 replications were measured to determine L* (lightness), a* (redness) and b* (yellowness). The total color difference (DE) was calculated using the following equation (Lemus-Mondaca et al., 2009):