Effect of aroma-producing yeasts in high-salt liquid-state fermentation soy sauce and the biosynthesis pathways of the dominant esters

Fermentation with excellent aroma-producing yeasts can enhance the flavour of soy sauce. In this work, Millerozyma farinosa CS2.23, Zygosaccharomyces rouxii CS2.42, and Candida parapsilosis CS2.53 were added to the high-salt liquid-state moromi to promote soy sauce fermentation. All three yeasts improved the TE of soy sauce, the highest of which reached 1.03 g/L with added CS2.42. Other quality indexes of soy sauce, including RS, TA, and AN, were not greatly affected. The volatile esters of soy sauce added to the three yeasts increased by 108.85%, 166.71%, and 113.61% compared with the control through GC-MS analysis. Obviously, CS2.42 had an excellent ability to produce esters. Studying the biosynthesis pathway of esters, CS2.42 has the best esterification ability, while CS2.53 has the advantage of alcoholysis ability. The exploration of the biosynthetic pathway of acetate and ethyl esters has laid a foundation for regulating esters in soy sauce fermentation.

Curcumin extracts from Curcuma Longa - Improvement of concentration, purity, and stability in food-approved and water-soluble surfactant-free microemulsions

Curcumin was extracted from Curcuma Longa employing a green, bio-based, and food-agreed surfactant-free microemulsion (SFME) consisting of water, ethanol, and triacetin. Concerning the high solubility of curcumin in the examined ternary mixtures, it was attempted to produce highly concentrated tinctures of up to a total of ~130 mg/mL curcuminoids in the solvent by repeatedly extracting fresh rhizomes in the same extraction mixture. The amount of water had a significant influence on the number of cycles that could be performed as well as on the extraction of the different curcuminoids. In addition, the purity of single extracts was enhanced to 94% by investigating several purification steps, e.g. vacuum distillation and lyophilization. Through purification before extraction, the water insoluble curcumin extract could be solubilized indefinitely in an aqueous environment. Additional stability tests showed that solutions of curcumin can be stable up to five months when concealed from natural light.

Solubilization and extraction of curcumin from Curcuma Longa using green, sustainable, and food-approved surfactant-free microemulsions

Curcumin is a powerful coloring agent widely used in the food industry. Its extraction from the plant Curcuma longa is commonly done with aqueous solvent solutions. In contrast to the conventional extraction methods, the present study aimed to compare two different green and bio-based surfactant-free microemulsion (SFME) extraction systems, which are approved for food and yield a higher extracting power of curcuminoids. Two SFMEs, water/ethanol/triacetin and water/diacetin/triacetin, were investigated via dynamic light scattering. Curcumin solubility in binary mixtures consisting of ethanol/triacetin or diacetin/triacetin was studied both experimentally and theoretically using UV-Vis measurements and COSMO-RS. The SFMEs were further examined and compared to a common ethanol/water (80/20) extraction mixture with respect to their extracting ability using high performance liquid chromatography. The SFMEs containing ethanol were found to extract ~18% more curcuminoids than the SFMEs containing diacetin and ~53% more than the ordinary ethanol/water mixture.

Effect of washing, soaking and pH in combination with ultrasound on enzymatic rancidity, phytic acid, heavy metals and coliforms of rice bran

Simultaneous reduction in activity of fat destabilizing enzymes (lipase and lipoxygenase), contaminants heavy metals (As, Cd, Pb, and Hg), antinutrient phytic acid and hazardous coliforms in rice bran was investigated. Application of washing, soaking the washed sample at different pH values (2, 6 and 9) alone or in combination with ultrasonication were examined. While washing was beneficial, its low efficiency acquired further treatment, which was prevailed by application of acidic pH and ultrasound (28 kHz) treatments. Free fatty acids and peroxide value, as indicators of enzymes activity, implied the effectiveness of treatments with adverse impact of sonication on peroxide value. Remarkably, reduction of dominant heavy metals (As, Pb and Zn) and phytic acid were synergistically facilitated by sonication. Coliforms growth was inhibited at pH 2 even at the absence of ultrasonic treatment. Evidently, combination of acidic pH and ultrasound is a practical approach to improve rice bran stability and safety.