Investigating the effects of pre-treatment and thin layer drying methods on quality of mango slices

Fresh Mangifera indica L. 'Tommy Atkin' with flesh colour parameters, of L* (47.70 +/- 5.6), a* (24.72 +/- 6.9) and b* (34.87 +/- 8.76), a mean TSS of 13.85 +/- 2.07 degrees Brix and firmness of 4.4 +/- 3.2 N were used for the drying experiments. This study investigated the effect of three drying methods, namely, open-air solar drying (OAD), modified ventilation solar drying (MVD) and convective oven drying (OVD) on quality parameters of 3, 6 and 9 mm mango slices with and without lemon juice pre-treatment. The study observations found relatively high colour changes on mango slices dried in OAD than for MVD and OVD. Thicker mango slices (9 mm) dried in OAD were darker, indicating that there was more browning, compared to the thinner slices (3 and 6 mm) which were dried in MVD and OAD. Sensory evaluations showed that panellists preferred treated mango samples. The overall acceptability of pre-treated mangoes dried with MVD (7.09 +/- 1.26) was not significantly higher (P>0.05) than that of mangoes dried in OVD (6.94 +/- 1.64) and OAD (6.51 +/- 2.07), respectively. In addition, the microbial counts showed that the dried mangoes were safe for human consumption, as pathogens were not detected. However, fungi and anaerobic bacteria counts were higher than the international stipulated limit of 1x10(3) CFU g(-1).