Jujube is widely used in rice porridge, tea, rice cakes and cookies, etc., as well as meat dishes such as Samgyetang(chicken stew with ginseng) or Galbi jjim(braised short ribs) which have high pharmacological action. When jujube is used in tea and rice cakes and cookies, jujube fruit flesh is sliced and only the fruit flesh is used. Therefore, residual fruit flesh around Jujube seed is discarded(about 25-30% of weight and volume of seed) and not used as industrial by products. To utilize this kind of residual Jujube seed, an unused resource, and to reduce the waste rate, it would be necessary to explore methods for using the residual Jujube seed actively as cooking material. Thus, if residual fruit flesh of Jujube seed is processed into concentrate that can be used for thickening agent of sauce(marinade) for Korean sauces, health-oriented sauce will be able to be manufactured from natural material.
Therefore, in this study, the residual fruit flesh around Jujube seed was extracted and concentrated. Using Jujube concentrate as a thickening agent, we prepared soy sauce-based Bulgogi sauce and red-pepper paste-based Grilled Pork sauce for meat cooking and then performed quality characterization and sensory test of quality of each sauce. The results were as below:

1. The yield rate of residual Jujube fruit flesh around the seed was 24.26% ± 1.41% based on weight ration in percentage. For volume ratio, 28.40% ± 1.79% of jujube seed fruit flesh was obtained. As Jujube fruit flesh was dried, weight ratio of jujube fruit flesh was found to be lower than its volume.

2. To develop sauce added with jujube concentrate, control sauce was needed, and furthermore, Xanthan gum was added to ensure a concentration a similar to that of sauce available in the market. For soy sauce, proper concentration of sauce as Bulgogi sauce was the most similar to that of commercial products added with 3.5 g of Xanthan gum. For red-pepper paste sauce for grilled pork, sauce containing 3 g of Xanthan gum was the most proper as it exhibited a concentration similar to that of commercial products.

3. Moisture content of soy sauce added with Jujube concentrate sauce peaked at 30.71% in the group added with 30%. As Jujube concentrate content increased, moisture content was significantly lower. The group added with 50% Jujube concentrate sauce showed the lowest moisture content with 22.99%. Meanwhile, Brix(%) was 30.82, the lowest, in control group. As the addition of jujube concentrate increased, Brix(%) rose significantly. However, the difference in Brix(%) was not significant and ranged between 33.00% and 34.38%.
Salinity(%) was the highest in control group with 1.38% and did not show any difference, depending on the amount of jujube concentrate added. Viscosity was 43.33 cP, the highest, in the group added with 50%. As the addition of Jujube concentrate increased, viscosity tended to increase significantly. The group added with 30% Jujube concentrate showed the lowest viscosity with 13.20 cP.
Spreadability was 8.88 cm, the highest, in the group added with 30%, as opposed to the tendency of viscosity. As the addition of Jujube concentrate increased, spreadability tended to decrease significantly. Thus, the group added with 50% exhibited the lowest spreadability with 6.85 cm. Chromaticity was the highest in control sauce with “L” value of 40.19, “a” value of 1.5, and “b” value of 24.57. As the addition of Jujube concentrate increased, “L” value, “a” value, and “b” value increased altogether.

4. For red-pepper paste sauce added with Jujube concentrate, the lowest moisture content(23.95%) was observed in the group added with 10% Jujube concentrate. As the addition of Jujube concentrate increased, the moisture content decreased, showing a significant difference.
The lowest Brix(%)(41.57%) was observed in the group added with 10% Jujube concentrate. As the addition of Jujube concentrate increased, Brix(%) increased significant. The highest Brix(%)(45.65%) was observed in the group added with 30% Jujube concentrate. Salinity(%) ranged from 0.68%(min.) to 0.92%(max.), and increased significantly as the addition of Jujube concentrate rose. Viscosity was the 8.69 cP, the lowest, in the group added with 10% Jujube concentrate.
Viscosity increased significantly as the addition of Jujube concentrate increased. The highest viscosity(76.68 cP) was observed in the group added with 30% Jujube concentrate. In contrast to the tendency of viscosity, the highest spreadability(10.67 cm) was observed in the group added with 10% Jujube concentrate. As the addition of Jujube concentrate increased, spreadability decreased significantly. The lowest spreadability(5.05 cm) was observed in the group added with 30% Jujube concentrate. Chromaticity was the highest in control sauce with “L” value of 32.25, “a” value of 9.24, and “b” value of 14.20. As the addition of Jujube concentrate increased, “L” value, “a” value, and “b” value declined slightly.

5. The results of sensory test of soy sauce added with Jujube concentrate showed that overall preference was the significantly highest for the sauce added with 35% Jujube concentrate based on preference test. Moreover, the preference was the highest for the sauce added with 35% Jujube concentrate even for appearance, taste, and flowability. Meanwhile, the results of differentiation test showed that there was a significant difference in color intensity, Jujube flavor, Jujube taste, sweet taste, and salty taste. However, no significant difference was observed for flowability.

6. The results of sensory test of red-pepper paste sauce added with Jujube concentrate showed that overall preference was the significantly highest for the sauce added with 20% Jujube concentrate based on preference test. Moreover, the preference was the highest for the sauce added with 20% Jujube concentrate in connection with appearance, flavor, taste, and flowability altogether. In the meantime, the results of differentiation test showed that there was a significant difference in color intensity, Jujube flavor, Jujube taste, and salty taste. However, no significant difference was observed in terms of sweet taste and flowability.

7. The results of preference test of beef bulgogi cooked with Jujube concentrate soy sauce showed that overall preference was the significantly highest for the sauce added with 35% Jujube concentrate soy sauce. In addition, the preference was the highest for the sauce added with 35% Jujube concentrate soy sauce in terms of flavor, taste, and texture characteristics of Bulgogi. However, no significant difference was observed in the preference towards appearance among samples. Meanwhile, the results of preference test of Grilled Pork cooked with red-pepper paste sauce showed that overall preference was the significantly the highest for the sauce added with 20% red-pepper paste sauce. Moreover, the highest preference was observed in terms of appearance, flavor, taste, and texture of meat.

Aforesaid results suggested that fruit flesh concentrate around Jujube seed could be used as sauce thickening agent and that overall preference for soy sauce and red-pepper paste sauce, both of which were added with fruit flesh concentrate, was higher than that for the sauces not containing any fruit flesh concentrate, implying that fruit flesh concentrate around Jujube seed had sufficient value as marinade used in meat seasonings.