|LI, XUAN - University Of California|
|ZHANG, ANG - Northwest Agriculture And Forestry University|
|ATUNGULU, GRIFFITH - University Of California|
|DELWICHE, MICHAEL - University Of California|
|Wood, Delilah - De|
Submitted to: LWT - Food Science and Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/28/2013
Publication Date: 11/1/2013
Citation: Li, X., Zhang, A., Atungulu, G., Delwiche, M., Milczarek, R.R., Wood, D.F., Williams, T.G., Mchugh, T.H., Pan, Z. 2013. Effects of infrared radiation heating on peeling performance and quality attributes of clingstone peaches. LWT - Food Science and Technology. 55(1):34-42. doi: 10.1016/j.lwt.2013.08.020.
Interpretive Summary: Peeling is widely used in the food processing industry to produce premium quality canned fruits and vegetables. In this study, the effectiveness of IR dry-peeling of peaches was comprehensively investigated for different varieties of peaches used for peeling. Peeling performance and peeled product quality of IR heated peaches were evaluated and compared with the conventional lye method. The impact of IR heating on temperature and microstructural changes in peach tissues were also studied. Results showed that 180 s IR heating for medium size peaches under an emitter gap of 90 mm yielded peelability above 90% and peeling yield over 96% and produced peeled products with comparable firmness and color to wet-lye peeled peaches. Surface temperature increased rapidly during IR heating (>100°C) whereas the flesh temperature at 16 mm beneath the skin remained relatively low (<45°C). The results of heating time and emitter gap can be used as guidelines for designing IR peeling device for peaches.
Technical Abstract: Salinity and wastewater disposal problems associated with the conventional wet-lye method for peeling clingstone peaches result in considerable negative environment impacts. This study investigated the efficacy of using infrared (IR) heating as an alternative method for peach peel removal without using water and chemicals. Peaches sorted into three size categories were double-sided heated under IR with three emitter gaps for a range of heating times from 90 s to 180 s. Peeling performance (including the peelability, peeling yield, and moisture loss as well as quality attributes including firmness and color) of IR peeled products was compared with those peeled by regular wet-lye peeling. Temperature profiles on the peach surface and interior were monitored at eight locations during and after IR heating. Microstructure changes in cellular tissues nearby peach skin were examined for peaches heated by lye and IR with the fresh peach tissue as a control. Results showed that 180 s IR heating for medium size peaches under an emitter gap of 90 mm yielded peelability above 90% and peeling yield over 96% and produced peeled products with comparable firmness and color to wet-lye peeled peaches. Surface temperature increased rapidly during IR heating (>100°C) whereas the flesh temperature at 16 mm beneath the skin remained relatively low (<45°C). Thermal expansion of cell walls and collapse of cellular layers adjacent to the skin were found in IR heated peaches and differed from the microstructural changes observed in lye treated samples, indicating a mechanistic difference of the two peeling methods. Promoting uniform and rapid surface heating is essential to further develop IR heating as a non-chemical method for peach peeling.