Influence of Osmoconcentration, Continuous High-Frequency Ultrasound and Dehydration on Properties and Microstructure of Rabbiteye Blueberries

Rabbiteye blueberries were osmoconcentrated for 12 h, and for 3 h with and without continuous high-frequency ultrasound (CHFU) and then air dehydrated (70°C, 10 h). Osmoconcentration increased solids gain, moisture loss, soluble solids, and bulk density. Long osmoconcentration for 12 h can be reduced with CHFU with similar results. Scanning electron microscopy (SEM) micrographs indicated that berries without pretreatment suffered the highest degree of tissue collapse. They also had the highest rehydration ratio and may be ideal for use in breakfast cereals. Osmoconcentrated berries may be used as snack food or in cereal bars due to high bulk density and low rehydration ratio.

Keywords:

• SEM
• Ultrasound
• Blueberries
• Rehydration ratio
• Dehydration
• Osmoconcentration

This work was supported in part by USDA-IFAFS Grant No. 2001-52101-11446 and by MAFES under project MIS-321376.

Notes

abcd = Means within row, before and after dehydration, followed by the same letter do not differ (p > 0.05).

¹Treatments: C, Thawed berries without pretreatment; O12, Osmotically concentrated berries for 12 h; O3, Osmotically concentrated berries for 3 h; O3 + U, Osmotically concentrated berries for 3 h with CHFU; C + D-Thawed berries without pretreatment and dried; O12 + D, Osmotically concentrated berries for 12 h and dried; O3 + D, Osmotically concentrated berries for 3 h and dried; O3 + U + D, Osmotically concentrated berries for 3 h with CHFU and dried.

²LSD_0.05, Least significant difference.

³CV, Coefficient of variation.

⁴Data not available.

Approved for publication as Journal Article No. J-10777 of the Mississippi Agricultural and Forestry Experimental Station (MAFES), Mississippi State University.