Change in color and other fruit quality characteristics of tomato cultivars after hot-air drying at low final-moisture content

Abstract

The present study aimed to evaluate the drying quality of three tomato cultivars (Amoroso, Berlinto and Messina) at low final-moisture content. Tomatoes were cut into slices and hot-air-dried from 92% (wet basis) to 12% final moisture content at 55 degrees C, 65 degrees C and 75 degrees C at 1.5 m/sec air flow. Color, total soluble solids (TSS), titratable acidity (TA) and ascorbic acid (AA) content were measured in both fresh and dried tomatoes. Brightness of the dried tomato slices was significantly decreased, while intensity of the red and yellow colors and brightness of the red color (a*/b*) increased. Low overall color change (DeltaE) was obtained at the lowest drying temperature (55 degrees C). Messina and Amoroso showed a higher a* value and lower DeltaE, respectively. The TSS content was increased, while the TA and AA contents were decreased through drying. This study shows that it is possible to hot-air dry tomato slices to a final moisture content of 12% maintaining quality that is comparable with studies where the final-moisture content was higher (15% or more).

The effects of middle infrared radiation intensity on the quality of dried tomato products

“…Ashebir et al . () found a notable decrease in L * value of tomatoes of 3 different varieties that were dried with hot air. Also, Arslan & Ozcan () indicated remarkable differences in L *, a * and b * values of tomatoes, which were dried with microwave, hot air and sun drying.…”

“…() dried tomatoes with hot air and reported that Δ E was 7.53 for osmotically pretreated tomatoes, while it was 13.52 for those without any pretreatment. Δ E of the hot‐air‐dried tomatoes of three different varieties was ranged between 14 and 17 (Ashebir et al ., ). It was reported that Δ E of tomatoes ranged between 2 and 16 for hot air drying (at 65, 75 and 85 °C and with the Av of 1.5 and 2.0 ms −1 ), 27 and 37 for vacuum drying, 23 and 26 for freeze‐drying, and 19 and 26 for sun drying (Hasturk‐Sahin et al ., ).…”

Monitoring and Optimization of the Process of Drying Fruits and Vegetables Using Computer Vision: A Review

“…High temperature, long drying cycle and exposure to oxygen cause a strong reduction of its concentration in fruit and vegetables. Tomato, indeed, after drying at 75 • C loses about half of its original AA content [34]. Furthermore, it has been observed, in a study on fluted pumpkin leaves, that high temperature over a short-time at low pH leads to a better retention of AA than a lower temperature over a long process at high pH [35].…”

Modern drying techniques in fruits and vegetables to overcome postharvest losses: A review

“…Drying of tomatoes is used for long‐term storage either in the form of flakes or powder and various methods such as hot‐air, solar, sun, microwave, and FD have been used (Ashebir, Jezik, Weingartemann, & Gretzmacher, ). Tomato drying at high temperature deteriorates its color and vitamin C contents which affects its quality (Ashebir et al, ; Kerkhofs, Lister, & Savage, ). Hot‐air drying can be useful in maintaining the quality characters if commodity is dried at temperature 75°C and moisture is maintained up to 12% instead of 15% (Ashebir et al, ; Khazaei, Chegini, & Bakhshiani, ).…”

“…Tomato drying at high temperature deteriorates its color and vitamin C contents which affects its quality (Ashebir et al, ; Kerkhofs, Lister, & Savage, ). Hot‐air drying can be useful in maintaining the quality characters if commodity is dried at temperature 75°C and moisture is maintained up to 12% instead of 15% (Ashebir et al, ; Khazaei, Chegini, & Bakhshiani, ). Convective solar drying and concentrated solar drying techniques in tomato crops were found more effective in quality retention, reduction in drying time, and cost‐effectiveness.…”