Development in Concentration Method of Soy Sauce Color Components by Nano-filtration Membrane

Abstract

Naturally brewed soy sauce has been used in flavoring not only Japanese but also international foods. The harmony of aroma, taste and color in the cuisine is important and soy sauce has been playing a big role. Especially the color tone in the processed food is an important standard of quality evaluation. The pigment enrichment method of naturally brewed soy sauce was initially developed by NF membrane filtration system in order to adjust the color tone. Two types of NF membrane elements were selected by considering pressure drop and rejection of color components. The color index was defined to measure the capability to dye foodstuff. Brix concentration was found to be in strong correlation relationship with the color index. Continuous measurement of brix concentration was indispensable in the NF membrane system to adjust the color index of super-dark-color soy sauce. This product was evaluated by ordinary analysis, gas chromatography and sensory evaluation to compare with the dark color soy sauce heated with some sugar and acids. Super dark color soy sauce was admitted to be useful as a pigment to regulate the color of many kinds of foodstuff.