Studies On Extraction And Properties Of Melanin And Soy Isoflavones From Soy Sauce Residue

Soy sauce residue is the remaining residue of the brewing raw materials after brewing during soy sauce production,but the ingredients in raw materials have a low utilization rate except protein and starch.With China's soy sauce production grows year by year,a large number of soy sauce residue has become an urgent problem of soy sauce industry.As water,salt and oxidized oil content in soy sauce residue is high,at this stage,soy sauce manufacturers usually sell the soy sauce residue at a low price to the local farmers as a feed or drop it directly,resulting in a lot of waste of resources,and improper handling can also cause environmental pollution.Therefore,it is significant to develop the rich bio-active material resources in soy sauce residue,and then make full use of them.Soy sauce residue contains not only protein,oil and cellulose,but also contains a lot of melanin,soy isoflavones,saponins,phospholipids and other bioactive substances,can be widely used in healthy food and pharmaceutical industry.Soy sauce melanin is extracted from soy sauce,and it has its own anti-oxidation effect,so it is a natural melanin with big development potential.In food,medicine,health and other fields,soy sauce melanin has a good development and application prospect.Soy isoflavones is a natural phytoestrogen,with lots of biological effects,not only has anti-tumor effect,but also has a preventive and therapeutic effect on aging,cardiovascular disease,osteoporosis and menopausal syndrome.In this study,the soy sauce melanin was extracted by the method of organic solvent and ultrasonic assisted extraction,the soy isoflavones in the soy sauce residue extract was recycled by ethyl acetate.Also the properties of soy sauce melanin and soy isoflavones were analyzed and the melanin was be used to the production of food.This study offers theoretical basis and experimental data for the popularization and application of soy sauce melanin and soy isoflavones.The main contents and results are as follows:1.Study on extraction technology of soy sauce melaninThe soy sauce melanin was extracted by the method of organic solvent and ultrasonic assisted extraction,and the melanin crude was enriched and separated by DA201-C?macroporous resin,then the dark brown melanin solid was obtained.The results showed that the optimum extraction conditions of melanin in soy sauce residue were alcohol concentration 65%,solid-liquid ratio 1:1.75(g/m L),extraction time 24 h,ultrasonic time 35 min.Under this condition,the yield of melanin was 1.8g/100 g.2.Determination of the basic components of soy sauce and its propertiesIn the determination of the basic components,the contents of total nitrogen,total sugar and sodium chloride were 7.894g/100 g,3.157g/100 g and 1.08g/100 g,respectively.In spectral analysis,soy sauce melanin had a very strong absorption peak both in the ultraviolet and infrared regions.In the analysis of melanin stability,the melanin was easily oxidized by H2O2,and Na2SO3 had some hyperchromic effect on it.Sucrose,sodium benzoate,potassium sorbate and light had little effect on the melanin.Acidic environment and a high temperature above 80? had a degradation effect on soy sauce melanin.In functional analysis,soy sauce melanin had a strong scavenging ability to DPPH·free radicals and·OH free radicals,and the scavenging rates were 70.4% and 64.6%,respectively.The melanin could also inhibit the synthesis of nitrosamines,and the the inhibition rate is up to 64.8%.3.Determination and functional study of soy isoflavones in the alcohol extractsSoy isoflavones in the alcohol extracts was recycled by ethyl acetate.The samples with the highest melanin yield also had the highest soy isoflavones yield about 37mg/100 g,analyzed by high performance liquid chromatography(HPLC).The scavenging ability of soy isoflavones to DPPH·free radicals was stronger than that of superoxide free radicals,and the scavenging rates were 93% and 43%,respectively.4.Soy sauce melanin applicationThis part tried to use soy sauce melanin for the production of chocolate cookies,and checked the cookie color,aroma,taste,shape and other sensory indicators after add soy sauce melanin.Cookies were brown,colored evenly,rich of aroma,and taste crisp.