The Korean traditional hot sauce gochujang has been reported to have biological activities. Different kinds of gochujang products were prepared based on combinations of a fungal rice koji with two kinds of bacterial soybean mejus. Diets that included gochujang products were fed to rats and anti-obesity effects were investigated. Gochujang products reduced body weight gains, epididymal fat weights, and triglyceride levels in the serum and the liver. Effects were exerted by the diet that included the non-fermented gochujang mixture, increased using a fungal rice koji, and further enhanced using a bacterial soybean meju. Dietary effects were apparently induced via inhibition of the lipogenic enzymes fatty acid synthase, malic enzyme, and lipoprotein lipase by gochujang products in epididymal adipose tissues, and inhibition of glucose-6-phosphate dehydrogenase in the liver. High levels of capsaicin and genistein in gochujang products are considered to contribute to anti-obesity effects.

In this study, we compared the antiobesity effects between gochujangs prepared using different koji products and Tabasco hot sauce in rats fed a high-fat diet (HFD). Male Sprague-Dawley rats were fed HFD containing four different types of 10% gochujang powder or 0.25% commercial Tabasco sauce powder for 8 weeks. The body weight gain, liver and epididymal and mesenteric fat pad weights, serum leptin levels, and lipogenesis-related mRNA levels of HFD-gochujang supplementation groups were significantly decreased compared with those of the HFD group. In addition, gochujang supplement significantly reduced adipocyte size; hepatic triglyceride and total cholesterol levels; the occurrence of fatty liver deposits and steatosis by inhibiting lipogenesis through downregulation of fatty acid synthase, acetly-CoA carboxylase, and glucose-6-phosphate-dehydrogenase. These effects were greater in the gochujang-supplemented groups than the Tabasco hot sauce-supplemented group. The gochujang prepared by nutritious giant embryo rice koji and soybean koji was most effective in terms of antiobesity effects, compared with the other tested gochujangs. In gochujangs, the antiobesity effects are mediated by high levels of secondary metabolites such as isoflavone, soyasaponin, capsaicin, and lysophosphatidylcholine. The current results indicated that the gochujang products have the potential to reduce fat accumulation and obesity.

The aim of this study was to compare whether gochujang products prepared using giant embryo rice koji (rice gochujang, RG) and wheat koji (wheat gochujang, WG) have anti‐obesity effects on rats fed a high‐fat diet (HFD), who served as a model for obesity. The nutritional composition of RG and WG including proximate constituents, amino acid and fatty acid compositions were investigated. Consequently, the secondary fermented metabolites were analyzed in RG and WG by ultrahigh‐performance liquid chromatography and mass spectrometry. Rats were fed a HFD containing 10% RG powder (HFD‐RG) or 10% WG powder (HFD‐WG) for 8 weeks. Body weight gain, weights of liver, epididymal, retroperitoneal, perirenal, and total white fat pads, and levels of serum triglyceride (TG), total cholesterol, low‐density lipoprotein cholesterol, and leptin were lower in all gochujang groups than in the HFD group. Furthermore, RG and WG treatment decreased the hepatic TG content and lipid accumulation and significantly reduced the size of epididymal adipocytes. These effects are probably mediated through inhibition of hepatic fatty acid synthase, acetyl CoA carboxylase, malic enzyme, and adipose tissue lipoprotein lipase activities. The anti‐obesity effect was slightly greater in the HFD‐RG group than in the HFD‐WG group. This effect may be attributed to secondary metabolites, such as capsaicin, genistein, daidzein, soyasaponin, and lysophosphatidylcholines, contained in gochujang prepared using giant embryo rice or wheat koji.