Vibratory motions are common to packaged products in the shipping and distribution environment. Using an MTS vibration table, low-fat plain yogurt (packaged in various shipping containers) was vibrated and then evaluated for phase separation (whey-off) during storage. Three types of damage were apparent: (a) slight or definite whey-off, (b) cracked or broken coagulum and (c) completely disrupted coagulum. After 10 d of storage, whey-off was quantitated. Slight and definite whey-off corresponded to 0.2 to 0.6% (wt/wt) and 0.6 to 1.8% (wt/wt), respectively. Most damage was observed in the top layers of vibrated stacks (10 high). Stretch overwrapping the shippers proved most effective in reducing syneresis, with less than 1% of the primary containers evaluated showing phase separation.

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Author notes

1School of Packaging.

2Department of Food Science and Human Nutrition.