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ARS Home » Pacific West Area » Albany, California » Western Regional Research Center » Healthy Processed Foods Research » Research » Publications at this Location » Publication #221460
Title: Effect of Berry Size and Sodium Hydroxide Pretreatment on the Drying Characteristics of Blueberries under Infrared Radiation Heating

Author
item SHI, JUNLING - UC DAVIS, DAVIS, CA
item Pan, Zhongli
item McHugh, Tara
item Wood, Delilah - De
item ZHU, YI - UC DAVIS, DAVIS, CA
item AVENA-BUSTILLOS, ROBERTO - UC DAVIS, DAVIS, CA
item HIRSCHBERG, EDWARD - INNOVATIVE FOOD, INC, CA

Submitted to: Journal of Food Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/27/2008
Publication Date: 8/12/2008
Citation: Shi, J., Pan, Z., Mc Hugh, T.H., Wood, D.F., Zhu, Y., Avena-Bustillos, R.D., Hirschberg, E. 2008. Effect of Berry Size and Sodium Hydroxide Pretreatment on the Drying Characteristics of Blueberries under Infrared Radiation Heating. Journal of Food Science. 73(6):E259-E265.

Interpretive Summary: This research studied the effect on the drying characteristics of blueberries under infrared radiation (IR) heating of berry size and dipping pretreatment in hot sodium hydroxide (NaOH) solution. Changes in the microstructure and diffusion coefficient of the berries after the NaOH pretreatment were also determined, using scanning electronic microscopy and Dynamic Vapor Sorption (DVS), respectively. The results showed that blueberries can be efficiently dried with IR heating.

Technical Abstract: This research studied the effect on the drying characteristics of blueberries under infrared radiation (IR) heating of berry size and dipping pretreatment in hot sodium hydroxide (NaOH) solution. Changes in the microstructure and diffusion coefficient of the berries after the NaOH pretreatment were also determined, using scanning electronic microscopy and Dynamic Vapor Sorption (DVS), respectively. To quantify the effect of berry size, non-pretreated bulk blueberries were sorted into six groups based on their diameters and dried at 70oC. To determine the effectiveness of NaOH pretreatment in improving drying characteristics, bulk blueberries of different sizes, both non-pretreated and NaOH pretreated, were dried at constant temperatures of 80 and 90oC, and variable temperatures of 70oC for 50 minutes followed by 90oC for 50 minutes. The NaOH pretreatment used 93oC 0.1% NaOH solution with 5 minutes dipping time. Results showed that the drying rate increased with decreased berry size. Average moisture diffusivity was in the range of 5.89 to 8.13 m2/s at 70°C. The NaOH pretreatment increased drying rate and moisture diffusivity and reduced the number of broken berries, especially at high drying temperatures. Results from SEM observation and DVS showed that the increase in diffusivity coefficients of berry coat and loss of intact microstructure in coat and tissue cells might contribute to the effect of NaOH pretreatment on the IR drying of blueberries.