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To date, the quality and safety of frozen bokbunja have not been clearly assessed. To produce high-quality frozen bokbunja, the optimal freeze-thaw conditions need to be explored. The most popular cultivar (Rubus occidentalis) in Korea was selected for this study. To determine the changes in the quality of frozen R. occidentalis berries, different freezing temperatures were used. The berries were frozen at −20, −45, and −70oC immediately after harvest. The drip ratio, hardness, pH, sugar content, color, and anthocyanidin content of the frozen and thawed samples were analyzed. The drip ratio, sugar content, and hardness of the berries correlated significantly with the freezing temperatures. The color and pH of the berries were not significantly affected by the freezing conditions. Frozen leaks between cells reduced significantly with decreasing temperatures. The freeze-thawing process significantly reduced the total aerobic bacteria and inhibited the growth of yeast/mold in the berries to about 2 log scales.

Garaedduk made with various levels of buckwheat flour (0, 15, 30, and 45%) for rice flour was prepared using retrogradation-retardation technology and their physical and sensory properties were investigated. The moisture content of garaedduk decreased and the color differences increased as the ratio of buckwheat flour to rice flour increased. During storage at 4 o C, the hardness values of garaedduk made with 15 and 30% buckwheat flour were maintained for up to three days. Immediately after manufacture, garaedduk made with higher levels of buckwheat flour had reduced overall acceptability. However, there was no significant difference in the overall acceptability of garaedduk made with 0 and 15% of buckwheat flour after storage. Therefore, buckwheat flour can replace rice flour with retrogradation-retardation technology to inhibit the starch retrogradation of garaedduk, which maintained its overall quality at a buckwheat flour level of 15%.