Diversification, advanced quality, and premiumisation of products are appearing with gradually growing world sauce market, and consumers demand for not only flavor of products but also additional product functions is increasing. Also, preference for products that kept the natural flavor and function of materials instead of artificial ingredient is increasing as well. However, oyster sauce products are not fulfilling the needs of consumers who wish to keep the original flavor and function of oyster because oyster which is the main ingredient of most oyster sauce products is not contained as it is but is contained in oyster extract or oyster concentrate form. Therefore, this study intended to compare component changes of grinded oyster fermentation through quality evaluation of commercial oyster sauce to be used as basic data for manufacturing fermented oyster sauce using oyster fermentation.
The moisture content of commercial oyster sauce showed 48.26-72.72 % range of difference by product, and the average moisture content was 63.53 %. This is considered to have a close relationship with convenience of use when consumers use oyster sauce. The salinity content of commercial oyster sauce showed the range of 9.77-13.86 %, and the average salinity content was 11.93 %. The salinity content of sauce is very closely related with the amount of sauce usage. Therefore, appropriate moisture content and salinity content are considered necessary for convenience of using oyster sauce.
The total nitrogen content of oyster fermentation was 1.67 % and total nitrogen content of oyster steaming concentrate was 1.65 %, but the total nitrogen content of commercial oyster sauce showed a big difference in the range of 0.18-1.33 % by each product. The amino nitrogen content of Oyster fermentation contained 827.94 mg/100 g and oyster steaming concentrate contained 822.36 mg/100 g of amino nitrogen content, but showed very big difference by each product as amino nitrogen content of commercial oyster sauce was 270.58-1102.43 mg/100 g. It was identified that many commercial oyster sauce products contain low total nitrogen and amino nitrogen content compare to oyster fermentation and oyster steaming concentrate.
The volatile basic nitrogen content of oyster fermentation was 49.06 mg/100 g and oyster steaming concentrate was 112.78 mg/100 g, and volatile basic nitrogen content showed a big difference by commercial oyster sauce in the range of 0.66-58.79 mg/100g. The average was 18.36 mg/100g. pH of oyster fermentation and oyster steaming concentrate was 5.72 and 5.97, and pH of commercial oyster sauce showed a big difference by product in the range of 5.46-7.01. The average was 6.21. Volatile basic nitrogen content and pH cannot be used as an index of quality evaluation because commercial oyster sauce contains various raw materials other than oyster, and it is considered that they can be used as a reference among various complex quality evaluation factors.
According to the result of measuring the degree of color of 11 kinds of oyster fermentation, oyster steaming concentrate, and commercial oyster sauce, the degree of color and yellowness of the entire commercial oyster sauce showed lower value compare to oyster fermentation and oyster steaming concentrate. It is believed that because caramel coloring is added to meet the preference for color of oyster sauce that consumers generally think.
This study selected an oyster sauce product with highest quality by analyzing physicochemical components of commercial oyster sauce to compare free amino acid composition with oyster fermentation and oyster steaming concentrate.
Each sample showed difference according to the manufacturing and processing method. Specially, the difference in Glutamic acid content was far higher in commercial oyster sauce products and this is considered to be because a large quantity of MSG, and artificial flavor, is added to strengthen insufficient flavor.
This study identified the excellence of oyster fermentation by comparing quality of commercial oyster sauce products with oyster fermentation, and intends to provide basic data for manufacturing fermented oyster sauce.