IR heating time effects
The IR heating time had a significant effect on peach peeling performance, including the peel ability, peeling yields, and moisture loss (p < 0.05). As seen in Table 1, the spray-off peel ability and hand-scrubbing peel ability of IR peeled peaches improved considerably when the IR heating time increased. The peeling yields decreased and the moisture loss increased with the increase of IR heating time. Color and firmness of peeled peaches were not significantly affected by the increase of IR heating time (p < 0.05). Compared to wet-lye peeling, changes of color of IR heated peaches were not as significant as peaches peeled by wet-lye method. We
observed that the color of peach flesh visually appeared brownish after lye treatment due to biochemical reactions introduced by lye diffusion. Lye peeled peaches had firmer texture than IR peeled peaches due to the longer heating time of IR. Although the wet-lye peeling had better peel ability and peeling yields than IR peeling, there is a potential to improve the IR peeling performance. As seen in Table 1, after 180 s IR heating at an emitter gap of 115 mm, peeling peaches of medium size can achieve the averaged spray-off peel ability of about 57 mm2/100 mm2 and the averaged hand scrubbing peel ability higher than 80 mm2/100 mm2 meanwhile
the peeling yields was above 90 g/100 g and the moisture loss of about 8 g/100 g wet weight. The approximately 90 g/100 g peeling yields after peel removals complemented a 10 g/100 g peeling loss, which consisted of the 8 g/100 g moisture loss attributed to the juice leaking and evaporation of water vapor during IR heating and a 2 g/100 g mass loss of flesh. The flesh loss should be minimized as much as possible since it is permanent. In practice, the moisture
loss is recoverable during the canning process.