|Hansen, James D|
Submitted to: Postharvest Biology and Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/25/2005
Publication Date: 6/1/2006
Citation: Bai, J., Mielke, E.A., Chen, P.M., Spotts, R.A., Hansen, J.D., Neven, L.G. 2006. Effect of a high-pressure hot water washing system on fruit quality, insects, and disease in apples and pears. Part I. Effect of different washing condition on fruit quality of d'Anjou' pears. Postharvest Biology and Technology. 40:207-215. Interpretive Summary: High pressure washers are being used in the pear industry to clean the fruit prior to packing. However, the impact of these high pressure washers and the organosilicone surfactants used as defoamers in the dump tank on fruit quality is unknown. Researchers at the USDA - ARS Yakima Agricultural Research Laboratory, in collaboration with scientists at Oregon State University, found that high spray temperatures caused surface damage to the fruit. They also found that organosilicones used as defoamers and detergents did not adversely affect fruit quality. Surface disorders, like scuffing, were more pronounced with fruit which have been stored for a over 3 months. There was not a significant effect of high pressure washing using room temperature water on fruit quality. High pressure washing can be used to effectively clean pears, control decay, and remove surface arthropods without significant effects on fruit quality.
Technical Abstract: 'd'Anjou' pears (Pyrus comminicum, L.), shortly after harvest, and after storage for three and four months in regular air (RA) or for four, seven and eight months in controlled atmosphere (CA) at -1°C were washed through a packing line with different wetting agents [0.1 % Silwet, 0.01 and 0.1% Deformer, and water], water pressures [regular and high-pressure (200-1000 kPa)], water temperature [control (tap water, 5-15 °C), 40 °C and 50 °C], and brushes [soft and firm], respectively. Effect of the washing conditions on fruit quality was investigated after 1 month storage at -1°C to simulate shipping condition, and then again after a week at 20 °C to simulate marketing condition. Hot water caused severe heat scald especially when water temperature was 50 °C the incidence of heat scald increased to over 50% for the fruit stored in RA for 3 months. Combined with hot water, 550 kPa high pressure washing increased the incidence of friction discoloration. There were lower incidences of friction discoloration and heat scald for the fruit stored in CA for 7 months, in comparison to that in RA for 3 months. However, those fruit could not ripen properly as indicated as high extractable juice content. Fruit washed at harvest had minor incidences of friction discoloration regardless of different brushes, water pressures and wetting agents. Fruit washed after storages in either 4 months RA or 4 or 8 months CA suffered high incidence of friction discoloration including scuffing symptoms and pressure marking. The firm brushes caused a higher incidence of friction discoloration mainly because of scuffing symptoms. However, no differences were found between different water pressures and wetting agents with respect to friction discoloration. Fruit stored for 4 months RA suffered 26-28% friction discoloration in comparison with that stored in CA as 16-18% in firm brush washing. Extended CA storage increased friction discoloration even with soft brush washing.